Shandong Minhe Animal Husbandry Co., Ltd. Resource ......technology in the biogas fermentation jar,...

Special Chapter for Project analysis

Shandong Minhe Animal Husbandry Co., Ltd.

Biogas Engineering Project for Excrement and Sewage Treatment and

Resource Utilization

Supplemental Environmental Impact

Assessment Chapter One Project Analysis

Chapter Two Alternative Proposal Evaluation

Chapter Three Environmental Management Program

SHANDONG ACADEMY OF ENVIRONMENTAL SCIENCE

Jinan, Shandong Province

August 2007

Shandong Academy of Environmental Science

E1717 v2

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Chapter One Project Analysis

Shandong Academy of Environmental Science 1


I. About the Project

1.1 Nature and basic content

It is a new project to treat the high-concentration excrement, about 500t per day, of the 5

million chickens of Shandong Minhe Animal Husbandry Co., Ltd. (Minhe hereafter) and the

daily 1000t of cleaning sewage (after screening), with an annual processing capacity of

182,500t excrement and 365,000t sewage. It adopts the combined heat and power (CHP)

biogas generating set for power generation. The electric power is to be integrated into the

external power grid and sold. The residual heat produced by the generating set is to be used as

heat source to heat the anaerobic feed and preserve the temperature of anaerobic jar in winter.

It generates 30,000 m3 biogas per day, which can be used to generate 54,000kWh power per

day. Assuming the electricity rate is 0.594Yuan/kWh, it can bring a revenue of 11.70774

million Yuan every year. The daily power generation is 30,000×1.8=54,000 kWh; annual

power generation 19.71 million kWh. After the anaerobic fermentation of chicken excrement,

it can produce 10,376t biogas dregs (TS 75%; the moisture content decreases by less than 25%

through further dehydration in Phase Two project) and 490,000t biogas liquid every year,

which can be used as high-analysis organic fertilizer. And it can reduce the discharge of CO2

by an equivalent weight of 104,682 tons every year. The total investment of the project is

63.6785 million Yuan RMB. It needs 15 workers working 365 days every year, with each day

divided into three shifts. See Table 1 and Table 2 for the project contents and main

technological and economic indices:

Table 1 Project Contents

S/N Project

title Construction contents Note

1 Biogas

project

Pretreatment system, anaerobic digestion system, and

biogas liquid and biogas dregs separating system

2

Power

generation

project

Biogas purification and storage system, power generation

and residual heat utilization system etc.

3 Auxiliary Management house and blower house etc.



facility

Table 2 Main Technological and Economic Indices

S/N Title Unit Data Note

1 Processing scale Ton 1500 Process 500t fresh chicken

excrement and 1000t sewage.

2 Power generation 10,000k

Wh/year 1971

Biogas dregs Ton/year 11376

3

Organic

fertilize

r Biogas liquid

10,000

tons/year 49.0

In the preliminary period after the

project is completed, the biogas

liquid is provided free of charge.

4 Fixed number of workers 15

5 Working days per year Day 365 Four groups for three shifts, with

each shift being 8 hours

6 Fixed assets investment 10,000

Yuan 5095.9

Annual revenue 10,000

Yuan 1378.29

Annual profit 10,000

Yuan 384.74

1.2 Project Location

The project is to be located in the broiler chicken breeding base of Minhe, which lies in

Qujiagou Village, Beigou Township, Penglai City, Shandong Province. Lying in the hilly

terrain, the base is established through leveling up the mountainous terrain. The project to be

established is about 7.5km to the southwest of Penglai City. Around the project is farmland

and fruit tree land with villages such as Hanwang Village and Wujia Village in the vicinity.

1.3 General layout

This project is arranged compactly, and the technological process is smooth, which meets the

fire protection requirements of biogas engineering. The biogas generating set is laid on the

northern end of the production area, at some distance from the factory boundary and methane

storing tank, which effectively reduces the influence brought about by the methane risk



possibly. The finished biogas dregs and biogas liquid are stored in the south of the plant site.

There is a main gate in the southwest of the plant site to facilitate transportation. The greening

of the plant site is well and reasonably arranged, which helps reduce the influence of malodor

and noise on the environment. Generally speaking, the general arrangement of the plant is

reasonable. The project occupies an area of 19,998m2, with the building area being 12,312m2.

The buildings of the whole plant site are classified according to production type and fire

protection rating of civil architecture, and strictly comply with the relevant regulations of

Code for Design of Building Fire Protection (revision 2001).

All clear places in the plant site are covered with Chinese pine and other evergreen plants,

appropriately studded with parergon. The green belt is laid along the bounding wall, where the

grass and flower, evergreen broad-leaved shrub and arbor are planted to form the greening

screen. The evergreen shrub brush hurdle and broad-leaved arbor and flower and grass are

planted around the buildings and on both sides of roads. Through implementing these greening

measures, it will reduce the influence of stench on the ambient environment as much as

possible to provide good working and living environment for the site and facilitate the wind

resistance, noise resistance and dust resistance of the plant site. The green area is 6,900m2,

with the greening coefficient being 35%.

See Table 3 for the details of the main data for the general arrangement.

Table 3 Schedule of Main Data for the General Arrangement

S/N Item Unit Amount

1 Area of plant site m2 19,998

2 Area of buildings and constructions m2 1,960

3 Green area m2 6,900

4 Greening coefficient % 35

II. Technological Flow and Material Balance

2.1 Technological flow With “clean production, cyclic utilization of resource, and reducing discharging of pollutant”

as principle, this project adopts the anaerobic digestion as the core of technology and

combines with the cyclic economy mode of other process engineering to turn the excrement

into biogas and realize the goal of biogas combined heat and power, pluralistic utilization and

innocent treatment of biogas dregs and biogas liquid. Minhe processes the high-analysis




organic wastewater to produce renewable energy source (biogas, electric power, and heat

energy) and (solid or liquid) organic fertilizer. With anaerobic digestion as the core of

technology, the whole scheme combines with the “cyclic economy” mode of other process

engineering, whose contents mainly include: (1) pretreatment system, (2) high-analysis

efficient anaerobic digestion system, (3) biogas liquid and biogas dregs after-treatment system,

(4) biogas purification and storage system, (5) biogas power generation and residual heat

utilization system, and (6) auxiliary buildings and constructions etc. See Diagram 1 for the

technological flow.

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Note:

According to the experience of Denmark, for the biogas production with chicken

excrement, there are four key matters to be solved:

The first one is to remove sand. The sand ratio of excrement is commonly required to

be less than 1%. The sand ratio of chicken excrement TS of Minhe is 3%. During the

pretreatment process, it mainly removes sand grain through sand basin. In order to

remove the sand grain, the sand in the excrement sand basin should be cleared once

every year.

The second one lies in the chicken feather. The influence of chicken feather can be

reduced through the shear pump.

The third one is about ammonia. If the ammonia content of excrement is excessively

high, the operating efficiency of the system will be reduced. The ammonia content

contained in every ton of fermentation liquor in the biogas jar is generally required to

be no more than 3.8 kg/m3, and the total nitrogen contained is required to be no more

than 5 kg/m3 (because 25% of the total nitrogen can be converted into ammonia

nitrogen).

The fourth one is to desulfurate. The H2S contents of chicken excrement reach

1500-2000 mg/m3, which may seriously erode the equipment and generating set, so

the biological desulfurization technology must be adopted to purify the biogas.

2.1.1 Pretreatment technique

(1) Collection and transportation of chicken excrement

The broiler chicken excrement in the raising base is transported through pipeline. The

breeding chicken excrement in the raising base is transported to the biogas station

through vehicle. And it adopts the 8-hour working system.

(2) Homogenate sand basin

Put the collected chicken excrement into homogenate sand basin, and with rinsing

water, prepare it into the mixing chicken excrement sewage whose TS is 12%. The

sediment on the bottom of the basin is cleared periodically, and transported to be

buried in Penglai innocent garbage disposal plant.

2.1.2 Anaerobic digestion technique

(1) Anaerobic digestion reactor type

This project adopts continuous stirred tank reactor (CSTR), which is applicable to Shandong Academy of Environmental Science

Project Analysis

domestic animal excrement fermentation technique. It adopts the stirring and heating

technology in the biogas fermentation jar, which is a major breakthrough for the

biogas fermentation technique. The stirring facilitates the full contact between

fermentation material and microorganism in the jar and promotes the biogas yield

ratio of the equipment. The heating measure maintains the temperature inside the

anaerobic jar at the appropriate temperature for microorganism so as to ensure the

anaerobic jar can operate normally and stably in winter. The stirring and heating

greatly increase the biogas fermentation rate, so CSTR is also called high-velocity

biogas fermentation jar, which is characterized by high solid concentration, with TS

being 8-12%, enabling the biogas fermentation treatment for all domestic animal

excrement. Its merits include large processing capacity, large biogas output,

convenience for management, easy startup, and low transportation fees. It is generally

suitable for the area that mainly produces biogas and near which there are vegetable,

orchard, and farmland digesting and using the liquid organic fertilizer.

(2) Selection of anaerobic fermentation temperature

This project adopts the middle-temperature anaerobic digestion technique to treat the

chicken excrement, mainly considering the following two aspects:

a. The middle-temperature (35-38 ℃ ) fermentation can keep the anaerobic

fermentation biogas yield rate at a high level, and needs little heat to increase

temperature so as to reduce the heat consumption of the biogas engineering and save

the residual heat of generating set.

b. As the raw material of the biogas engineering of this project, the chicken excrement

contains high contents of ammonia. The free ammonia checks the anaerobic

fermentation. With the same total ammonia nitrogen concentration, the free ammonia

concentration in middle-temperature fermentation is lower than that in

high-temperature fermentation.

Therefore, this project adopts the middle-temperature fermentation technique to

reduce the check by anaerobic ammonia. And it doesn’t adopt the reutilization of

biogas liquid to ensure the stable and reliable anaerobic fermentation. The

high-temperature fermentation, if not managed appropriately, tends to bring about the

SHANDONG ACADEMY OF ENVIRONMENTAL SCIENCE 1

Project Analysis

ammonia check and abnormal fermentation etc.

The reasonable C/N for anaerobic fermentation is 15:1. The C/N ratio of fed material

of this project is 10~12:1. The ammonia content is a little higher. In general, it doesn’t

need to be adjusted, but the accumulation of ammonia nitrogen should be avoided in

the actual operation. For example, adopt the middle-temperature fermentation

technique to reduce the ammonia nitrogen concentration in the fermentation feed

liquid, and avoid the accumulation of ammonia nitrogen resulting from backflow of

biogas liquid.

(3) Anaerobic reactor structure

The anaerobic reactor of this project adopts the Lipp structure. Lipp jar-making

technology is to make use of work hardening theory and shell structure theory in the

plastic working of metals to make circular basin and jar with steel plate of certain

specifications through special technology and equipment and “spiral, double-fold, and

occluding” technique. Thanks to the mechanized and automated production and

adopting steel plate as construction material, Lipp technology has the merits of short

construction period, low price, and high quality etc. For the same construction scale,

its construction period is over 60% shorter than that of traditional production method.

The self-weight is only about 10% of the reinforced concrete tank, and about 50% of

the traditional carbon steel sheet welding tank. In this project, the part contacting

biogas, including cover of anaerobic jar, 1.5m high and above part of the jar wall, and

the part above liquid surface, is made of stainless steel. The other part is made of

galvanized sheet steel plus internal corrosion prevention. According to the experience

of biogas engineering of Denmark, the service life of anaerobic jar of this structure

can exceed 20 years.

(4) Stirring mode of anaerobic

This project adopts the central top stirring, which features: saving electric power, even

mixing of fermentation liquid, and preventing incrustation. The six anaerobic

fermentation jars of this project adopt the intermittent batch feed.

2.1.3 Solid-liquid separation and biogas dregs treatment technique

Put the anaerobic fermentation liquid in the biogas liquid after-fermentation basin for


Project Analysis

after-fermentation, collect the biogas, and then separate the liquid from the solid.

After the separation, the biogas dregs are further dehydrated in Phase Two project.

When the moisture content is reduced to less than 25%, it can be sold as organic

fertilizer. And the biogas liquid is discharged to the original 50,000m3 biogas basin to

be stored as the liquid organic fertilizer for the neighboring grapery, orchard, and

farmland etc.

2.1.4 Biogas purification and storage technique

The biogas coming from anaerobic fermentation jar is the mixed gas containing moist

steam. Apart from such gaseous fuel as CH4 and CO2, it contains H2S and suspended

granular impurity. H2S is not only toxic, but also very corrosive. The excessive H2S

and impurity will endanger the service life of generating set, so such purification

treatments as desulfurization and gas-water separation are required, among which the

desulfurization of biogas is the main issue.

The H2S content of biogas produced from chicken excrement wastewater is very high,

reaching 1500-2000 mg/m3, so the desulfurization is necessary. In this project, the

biological desulfurization measure will be adopted to desulfurize the biogas. The

biological desulfurization is to oxidize H2S into sulfur or sulfurous acid in the

micro-Aeration condition with colorless sulfur bacteria, such as sulfur oxide

thiobacilli and ferrous oxide thiobacilli etc. This desulfurization measure has been

widely used in Europe, and has been adopted in some projects in China. Its merits

include: not needing catalyst, not needing to treat chemical sludge, producing little

biological sludge, low energy consumption, and sulfur recoverable, and high

removing efficiency. Over 90% of H2S can be removed. After treatment, the H2S

content of biogas is lower than 200 mg/m3, which can meet the requirement of

generating set for the biogas.

According to the different oxygen supply amount, the biological desulfurization can

bring different products. The detailed reaction process is as follows:

H2S + 1/2O2 → S + H2O

H2S + 3/2O2 → H2SO3

The sulfur can be recovered and sold. And the sulfurous acid and very a little


Project Analysis

biological sludge can be returned to the biogas liquid to keep the nutritive equilibrium

of biogas liquid as organic fertilizer.

The biogas containing moist steam that is sent from anaerobic jar is stored in the gas

storing tank after the purification treatment of special equipment, such as biological

desulfurization tower, gas-water separator, and water condenser etc.

This project adopts the double-membrane dry-type gas storing tank to store the biogas.

It is composed of external membrane and internal membrane. The external membrane

constitutes the external ball shape of the gas storing tank. And the internal membrane

and bottom constitute the cavity to store biogas. The tank has an explosion prevention

blower fan, which automatically adjusts the amount of gas sent to biogas generator

according to the requirement to keep stable the internal gas pressure of the tank. The

external membrane has an upright hose, through which the explosion prevention

blower fan above-mentioned conveys the external air to the space between external

membrane and internal membrane so as to keep the external membrane spherical and

send the biogas out. In addition, it is equipped with ultrasonic range finder to

automatically adjust and control the biogas storing amount.

2.1.5 CHP generator allocation plan

This project adopts the CHP technology to make comprehensive use of the biogas

produced from chicken excrement waste and sewage of Minhe. It can be used for

power generation and heating to create considerable economic benefit, but also reduce

the drainage of greenhouse gasses, then control the pollution and improve the

environment.

The biogas is used to generate power through generating set. The generated electricity

power is integrated into the power grid to be sold, with remarkable economic benefit.

The exhaust heat produced by generating set produces 130℃ hot water through

needle tube heat exchanger. In winter, the hot water is mainly used to heat the

anaerobic feed, and the remaining is used as the heat source for the hencoop of the

chicken farm. In summer, the residual heat can be used to refrigerate the hencoop

through lithium bromide generating set and fan coil system (late phase project).

1) Generating set scale selection


Project Analysis

The generating set scale is decided according to the principle of “deciding energy

output through biogas amount”. The project produces 30,000 m3 biogas per day. The

heat value of 1m3 biogas is about 5,119 kcal, or 21.5MJ (the methane content of

biogas is 60%). The heat rate of 500GF1-1RZ biogas generating set is 12MJ/kWh.

Therefore, 1m3 biogas can be used to generate 21.5 MJ ÷12 MJ/kWh =1.8 kWh

electric power, then the generated power per day: 30,000×1.8＝54,000 kWh (i.e.

generated power per hour: 2,250 kWh), and then the generated power every year:

54,000×365＝19,710,000 kWh.

It plans to adopt the 500GF1-1RZ generating set. Based on the continuous power of

the generating set being 420kW and annual operating time being 7,200h, the number

of generating sets should be n=19710000/(7200×420)≈6.5. Therefore, it can install

7 generating sets.

According to the calculation based on biogas yield being 30,000m3/d or 1,250m3/h,

methane concentration being 60%, and unit power being 420kW, the number of

generating sets to which sufficient biogas can be supplied: 1250×1.8÷420＝5.36,

and based on the operating time being 8,760h, the average operating power of 6

normally operated generating sets is 375kW.

To sum up, it can establish a CHP biogas power station with seven 500GF1-1RZ

generating sets (6 in service and 1 standby), which is equipped with cooling

circulating system, power distribution system, gas feed system, residual heat

utilization system, and other auxiliary production systems.

Technological Parameters of 500GF1-1RZ Generating Set

Model of generating set 500GF1-1RZ

Model of engine Z12V190ZLDK-2A

Generator mark TF454-6 / 1FC6 454-6LA42-Z

Model of control panel PCK1-RB500 (optional: PCK1-RZ500)

Rated power (kW) 500

Rated current (A) 901


Project Analysis

Rated voltage (V) 400

Rated power factor, COSΦ 0.8 (hysteretic)

Rated frequency (Hz) 50

Gas heat rate, (MJ/kW·h) 12

Generating efficiency (%) 32

Startup manner 24V DC startup

Startup control mode Manual

Voltage adjustment mode Automatic

Mode of speed regulation Electronic

Excitation mode Brushless

Mode of connection Three-phase four-wire system

Circulated water cooling mode Open type (with heat exchanger)

Mode connection between

engine and generator Resilient coupling

Volume of oil sump (L) 180

Overall dimension (L×B×H)

mm 5,500×1,970×2,278

Mass of generating set (kg) 12,500

Main Technological and Economic Indices

S/N Item Unit Installation plan: 7×500kW (6 in

service and 1 standby)

1 Installed capacity kW 3,500

2 Continuous power kW 2,250

3 Annual operating time H 8,760

4 Comprehensive rate of

electricity use by

factory

% 2.5


Project Analysis

5 Annual average heat

loss from power

generation

MJ/kWh 12

6 Annual energy output kWh/ye

ar

1.971×107

7 Available exhaust heat kcal/yea

r

1.508×1010

8 Savable standard coal t/year 7.629×104

2.1.6 Main structure of CHP generating set

1. Cooling and circulating system: The seven 500GF1-1RZ generating sets (6 in

service and 1 standby) of the power station share one cooling and circulating system.

According to the performance requirement of 500GF1-1RZ, the cooling system of gas

generating set is divided into internal circulating system and external circulating

system. The two circulating systems exchange heat through the heat exchanger of the

generating set. The internal circulating system and external circulating system are

high-temperature cooling and circulating system and low-temperature cooling and

circulating system respectively. The temperature of influent water of high-temperature

cooling and circulating system is 35℃, and the return water temperature is 45℃. The

temperature of influent water of low-temperature cooling and circulating system is 25

℃, and the return water temperature is 35℃.

The high-temperature cooling and internal circulating is mainly used to cool engine

body and cylinder cover, while the low-temperature cooling and internal circulating is

mainly used to cool engine oil and air.

The internal circulating adopts the softened water. The consumption of each

generating set is about 5kg/d, and that of 6 generating sets is about 30kg/d. The

external circulating adopts the tap water. According to the calculation based on the

consumption of high-temperature and low-temperature cooling water of each

generating set being 40 m3/h, the total high-temperature and low-temperature


Project Analysis

circulating water consumption of 6 generating sets is 240m3/h. For the external

circulating, about 1,000kg-2,000kg water needs to be supplemented for each

generating set every day. If the multi-fan water tank cooling system is adopted, almost

no water will be lost, and then it almost doesn’t need to supplement water.

Flow of cooling and circulating system: circulating water basin→Y-shaped dirt

separator→circulating water pump→check valve→ influent water main pipe→

intelligent de-scaling electronic water treatment device→influent water branch pipe→

heat exchanger→return water branch pipe→return water main pipe→cooling tower→

circulating water basin

2. Power distribution system

1) Connect-in system: 3 of the 7 500GF1-1RZ generating sets constitute one group,

the other 4 generating sets constitute another group, which form unit connection with

a 2000kVA, 0.4/10.5kV, 2500kVA, and 0.4/10.5kV step-up transformer respectively,

and are integrated into the 10kV section of Qingou transformer station through

one-circuit overhead line.

Before the generating system is connected with the 10kV system, the electricity of

10kV system of Qingou transformer station is transmitted to the low-voltage side of

the power station through the step-up transformer to supply power for the auxiliary

system of the generating set. After the auxiliary system works normally, start the

generating set and check the synchronization at the 0.4kV side. The generating set

operates in parallel with user transformer station power source at the low-voltage side,

and is connected with the bus of 10kV system of Qingou transformer station.

2) Main electrical connection: 3 of the 7 500GF1-1RZ generating sets constitute one

group, the other 4 generating sets constitute another group, which form unit

connection with 2000kVA, 0.4/10.5kV, 2500kVA, and 0.4/10.5kV step-up transformer

respectively. The high-voltage connection adopts the single-bus desectorizing type,

and is connected with the bus of 10kV system of Qingou transformer station through

one-circuit high-voltage cable.

3) System of electricity for power station use: The low-voltage switch cabinet coil-in


Project Analysis

power source for the electricity for power station use adopts the double-power source

automatic switching device. The power sources are led from the 0.4kV bus of step-up

transformer station and local power grid respectively. The distribution voltage is

220/380V. The power distribution adopts the emanatory type. The AC contactor or

circuit breaker is controlled in site or in the switching room. As to the laying type, the

cable is laid along cable trench or through protecting tube under ground.

4) 10kV power distribution device: The KYN28A-12 moveable metal-enclosed switch

cabinet with five-protection function is adopted as the 10kV high-voltage switch

cabinet of the power station. And it is equipped with vacuum breaker and spring

operation mechanism. All coils in and coils out are ingoing cable and outgoing cable.

In Qingou transformer station, one GG-1A (F) high-voltage switch cabinet is

installed.

5) Integrated automation of power station

a. The generating set adopts 4 one-controlling-two TEM control systems (one TEM

controller controls two generating sets).

b. The generating set operating status is monitored in the generating set control panel

and TEM controller.

Synchronized system: every generating set has one control panel, in which the

synchronized device is installed to realize the low-voltage synchronized and parallel

operation.

3. Gas feed system

1) Feed system: One main DN300 biogas transmission pipeline is laid to transmit

biogas for six working generating sets. In order to ensure the normal operation of the

generating sets, silk screen filter and special flame arrester for pipeline are installed in

the biogas transmission pipeline. The above-ground aerial laying manner is adopted

for the main biogas transmission pipeline to transmit the biogas to the power station.

The diameter of biogas intake branch pipe of every 500GF1-1RZ generating set is

DN100. In order to be able to measure the biogas consumption by the power station,

one gas vortex shedding flow meter is installed in the DN300 main pipe for biogas

transmission. The flow meter is installed beside the generator room.


Project Analysis

2) Technological process of biogas feed

A → B → C → D→E → F→ G → G

A: double-membrane dry-type gas storing tank B: gate valve C: silk screen filter D:

special flame arrester for pipeline E: gas vortex shedding flow meter F: biogas intake

branch pipe G: manual butterfly valve H: generating set

4. Residual heat utilization system

Seven 500GF1-1RZ gas generating sets (6 in service and 1 standby) are adopted. The

tail gas of the generating sets carries a large amount of heat while it is discharged

from the inside of the generating sets. The temperature of such tail gas is about 550℃.

The tail gas discharged from the generating sets is directly led to needle tube heat

exchanger to generate 130℃ water with the residual heat. In winter, the 90℃ water

produced from water-water heat exchanger is mainly used to heat the material in

anaerobic jar and maintain the temperature needed for middle-temperature

fermentation in anaerobic jar, and the remaining hot water is used to heat some

hencoops. The softened water of the power station is made through the full automatic

water softener installed in residual heat pump house. The water used to supplement

the residual heat utilization system comes from the water supply pipeline network of

the chicken farm.

5. Other auxiliary production system

1) Ventilation: The ventilation design of generator room is mainly on the principle of

ventilation, with heat elimination into consideration. According to the dimension of

generator size and the calculation based on at least 30 times of ventilation volume per

hour, the ventilation louver is installed in the roof of the generator room. The

explosion-proof axial flow fan in the generator room is interlock-controlled by gas

alarm system, and it can also be controlled manually.

2) Fire protection: The fire protection targets include generator room, high-voltage

switch room, low-voltage switch room, outdoor transformer, and residual heat pump

room etc. The fire protection follows the principle of “being based on prevention and

combining prevention and fighting” and the requirement of GB50016-2006 Code for

Design of Building Fire Protection. It mainly depends on the mobile fire extinguisher.


Project Analysis

Besides, the power station is equipped with hydrants to conduct the security

protection.

3) Lightning grounding: Apart from the generator room designed on the basis of

second-class lightning-protection building, other constructions of the power station

are designed on the basis of third-class lightning-protection building. All equipment

whose metal case is not electrified, such as generator room, high-voltage switch room

and low-voltage switch room and generating set, control panel, TEM control cabinet,

and transformer, is reliably connected with the down lead. The down lead is evenly

laid around the construction, whose spacing is no more than 25m. The impulse ground

resistance each down lead is no more than 10Ω. The integrated grounding network is

set in the power station. In order to ensure the reliable operation of microcomputer

system in the power station, the grounding resistance is no more than 1Ω.

4) Gas alarm: The combustible gas concentration detector is set in the generator room

to detect the gas concentration and give alarm and interlock the explosion-proof axial

flow fan in the generator room to initiate it for ventilation.

2.2 Engineering unit design and equipment type selection 2.2.1 Pretreatment system

1. Grille water collection basin

Function: collect the rinsing water of the hencoop, and remove the impurity in

the sewage.

Volume: 500 m3

Size: Φ13 m × 4.5 m

Residence time: 12h

Structure: underground reinforced concrete structure, with cover.

The mechanical grille is set before the basin. Model: GSHZ-600 Width of equipment: 600 mm Overall width of grille: 820 mm Speed of passing grille: 0.5~1.0 m/s Depth of water before grille: 1 m Motor power: 1.1 kW


Project Analysis

Number: 1 The submersible sewage pump is set in the basin.

Function: convey the sewage in the water collection basin to the homogenate sand basin or biogas after-fermentation basin. Model: WQ40-10-2.2 Flow rate: 40 m3/d Head: 10 m Power: 2.2 kW Number: 2 (1 in service and 1 standby) Model: WQ40-15-4 Flow rate: 40 m3/d Head: 15 m Power: 4 kW Number: 2 (1 in service and 1 standby)

2. Homogenate sand basin Function: dilute the chicken excrement until the TS concentration is 12%, blend it evenly and remove the sand. Volume: 1680 m3 × 2 Size: Φ22 m × 4.5 m Structure: underground reinforced concrete structure, with cover. The feed inlet is in the pretreatment room. The shell of homogenate sand basin adopts the plastic extrusion panel for heat preservation. And there is heating pipe in the basin.

Homogenate basin blender Function: mix the excrement in the basin evenly Model: QJB 11/6 Power: 11kW Number: 4 (2 for every basin)

Spiral sand removal Function: discharge the sand in the bottom of homogenate basin

periodically Model: WLS320-18000 Power: 5.5kW Number: 2 (1 for every homogenate basin)

2.2.2 Anaerobic digestion and after-treatment part 1. Shear pump


Project Analysis

Function: cut chicken feather and foreign material Model: M-OVAS (R)/70-3.0/NC Flow rate: 40-70 m3/h Power: 3kW Number: 2 (1 in service and 1 standby), installed before charge pump

2. Charge pump Function: charge the anaerobic fermentation jar Model: NM090BY01L06V Flow rate: 40 m3/h Head: 40m Power: 11kW Number: 2 (1 in service and 1 standby)

3. Anaerobic digestion jar Function: Anaerobic digestion reactor Volume: 3200 m3 × 6 Size: Φ16 m × 16.5 m Structure: Lipp structure. The part contacting biogas, including cover of anaerobic jar, 1.5m high and above part of the jar wall, and the part above liquid surface, is made of stainless steel. The other part is made of galvanized sheet steel plus corrosion prevention. The angle of inclination in the jar top is 20°. Residence time: 23d Fermentation temperature: middle temperature 38℃ Volumetric gas yield: 1.6 m3/m3·d Anaerobic jar feed and operation manner: The feed rate of this project is 830 m3/d. There are 6 anaerobic jars, all of which have feed openings and discharge openings. And there are pipes connecting 1# jar and 2# jar, 3# jar and 4# jar, 5# jar and 6# jar. Such design makes the operation manner more flexible. It can either conduct parallel operation of 6 jars, or divide them into 3 groups to conduct series operation or parallel operation according to the requirement. Anaerobic jar heating manner: With the residual heat of biogas generating set as heat source, heat the external part of anaerobic jar with heating coil pipe. 5 heating coil pipes form one group, cross-arranged and heating by level to ensure the even heating. Anaerobic jar temperature preservation manner: The anaerobic jar


Project Analysis

temperature preservation adopts the double-layer 16cm-thick warming plate, installed outside of heating coil pipe in a staggered manner. The surface of anaerobic jar is covered with colorful steel plate. Anaerobic jar blender Function: mix the fermentation liquid to promote the contact between fermentation liquid and microorganism to enhance the gas yield. Installation manner: installed in the jar top Power: 11kW Rotating speed: 18rpm Number: 6 (1 for each jar) Anaerobic jar reflux pump: Model: NM063BY01L06V Flow rate: 20 m3/h Head: 20 m Power: 4 kW Number: 6 (1 for each jar)

4. After-fermentation jar (1) 1# biogas liquid after-fermentation jar Function: the biogas liquid after anaerobic fermentation further ferments in the jar, and then enters solid-liquid separation unit Volume: 4000 m3

Size: Φ25 m × 9 m Structure: The jar body adopts the Lipp structure. The top adopts the flexible membrane, which can collect biogas and prevent the emission of stench. Residence time: 5d Stirring machine: power: 7.5kw; number: 3 (2) 2# biogas liquid after-fermentation jar Function: ferment the residual sewage Volume: 4000 m3

Size: Φ25 m × 9 m Structure: The jar body adopts the Lipp structure. The top adopts the flexible membrane, which can collect biogas and prevent the emission of stench. Residence time: 5d Stirring machine: power: 7.5kw; number: 3


Project Analysis

5. Solid-liquid separation Solid-liquid separator: Model: VAN spiral extruding solid-liquid separator Power: 5.5 kW Number: 6 Working time: 12h Output of solid fertilizer: 60.91 t/d (21.32 tTS/d). The solid fertilizer produced every day is sent to organic fertilizer plant for the production of organic fertilizer.

6. Biogas liquid storage basin Function: The fermentation liquid after solid-liquid separation can be stored as the liquid fertilizer for the neighboring orchard, grapery, and farmland etc. Volume: 50,000 m3 (original one of the company)

After the treatment of chicken excrement and sewage of the hencoop through the above treatment facility, the COD removing rate for chicken excrement can exceed 95%, and that for sewage can exceed 80%. 2.2.3 Biogas desulfurization and biogas generating set 1. Biogas purification system (1) Biological desulfurization tower

Function: remove H2S in the biogas with biological measure Model: STS-2000 Processing amount of each tower: 220 m3/h Size: Φ2 m × 6 m Number: 6 Power of each tower: 1 kW

(2) Gas-water separator Model: GS-1000 Processing amount: 220 m3/h Number: 6

(3) Water condenser Model: NS-600 Number: 10

(4) Dry-type flame arrester Model: HF-200 Number: 6


Project Analysis

(5) Biogas flow meter Model: JLQD-100/220 Flow rate: 220 m3/h Number: 6

(6) Biogas component detector Model: BIOGAS-905 Detection item: CH4, H2S, O2, and CO2Number: 3

2. Biogas storing system Double-membrane dry-type gas storing tank Function: store the purified biogas Volume: 2000 m3

Size: Φ16.9 m × 12.7 m Structure: The double-membrane dry-type gas storing tank is composed of external membrane, internal membrane, bottom membrane, and concrete foundation. The cavity formed by internal membrane and bottom is used to store biogas. It is air tight between external membrane and internal membrane. The external membrane is ball-shaped after it is filled with gas. The tank has an explosion prevention blower fan, which can automatically adjust the amount of gas input/output to keep stable the internal gas pressure of the tank. The internal membrane, external membrane, and bottom membrane all adopt the membrane imported from Germany Mehler, which is welded through HF welding procedure. The material surface undergoes special treatment and coated with high-intensity polyester fiber and methacrylate vanish. The gas storing tank is ultraviolet resistant and leakage-proof. The membrane doesn’t react with or is affected by biogas. And its tensile strength is great. The applicable temperature is -30~60 �. Supporting equipment: 1 explosion prevention blower fan, used to provide pressure for the tank; 1 water seal; influent/effluent water pipe and condensed water drainage pipe (pre-buried in the concrete construction period); 1 ultrasonic ranger finder, installed inside of external top membrane and used to measure the height of internal membrane to decide the current gas storing amount; 1 sight glass, installed in the external membrane to observe the inside of the tank; leakage-proof device, used to convey the surplus biogas to the biogas boiler for automatic combustion when the tank is full of biogas, which can effectively prevent the leakage of biogas.


Project Analysis

3. Biogas power generation system Function: generate power with biogas with fuel to realize the combined heat and power. Generating capacity of biogas: 1.8 kWh/m3

Daily power generating time: 24h Annual working time: 7,200h Installed capacity: 500 kW × 7 (6 in service and 1 standby) Daily energy output: 54,000 kWh Number: 7

4. Hot water storing tank Function: The residual heat of biogas generating sets is stored in the upper part of hot water storing tank in the manner of 90℃ water. After it is used, the 60℃ water returns to the lower part of the tank, and is pumped into the biogas generating sets for heat exchange. Volume: 300 m3

Size: Φ6 m × 12 m Structure: Aboveground Lipp structure. The tank body adopts the polyurethane material for heat preservation.

Circulating pump Function: hot water circulation Model: 80HGR50-12.5 Flow rate: 50 m3/h Heat: 12.5 m Power: 3 kW Number: 2 (1 in service and 1 standby)

2.3 Material balance, water balance, and heat balance

2.3.1 Available broiler chicken excrement resources

The company has 1.3 million breeding broiler chicken (feed every chicken with about

0.7g grit every day) and 3.7 million broiler chicken. The company produces 500t fresh

excrement (with the TS content being about 20%) and 1,000t rinsing water (after the

grille treatment, among them, 330t is used for blending chicken excrement, and the

other 670t goes through the after-fermentation directly) per day.

The mass of dried chicken excrement: 500 t/d x TS20% =100 t/d, and the sand content

in the chicken excrement: 1,300,000 x 0.7 x 10-6 t/d = 0.9 t/d. According to the


Project Analysis

calculation based on every ton of dried excrement (TS) producing 300m3 biogas, the

daily biogas output is: 100 x 300 = 30,000 m3. After the chicken excrement is

collected, it needs to be prepared into excrement water with TS being 12% in the

homogenate basin, so the demand for water is: 100/12% - 500 = 330 t/d. Such water

mainly comes from the rinsing water of the animal farm. The total mixed excrement

amount is 830t/d.

2.3.2 Material (TS) balance

100t material is fed per day. 0.9t is removed in the pretreatment phase, including mud

and sand and a little excrement dregs, which will be transported and used as compost.

And 66.53t is consumed in the anaerobic phase. Such TS consumption is the main

part for biomass energy conversion and biogas production. In the anaerobic phase, the

TS output is 32.57t. After the solid-liquid separation, 65% (21.32 t/d) of them become

solid organic fertilizer, and the other part goes into the biogas liquid basin. See Table

2.3.1 for the calculation of material (TS) balance.

Table 2.3.1 Calculation of Material (TS) Balance

Phase Processing unit Input amount (t/d) Consumption (t/d)

Pretreatment

phase Homogenate sand basin 100.00 0.90

Anaerobic phase Anaerobic reactor 99.10 59.50

After

fermentation

phase

Biogas after-fermentation

jar 39.60 7.03

Solid-liquid

separation phase Solid-liquid separator 32.57 21.32

Biogas liquid storage unit 11.25 -- Storage phase

Biogas dregs storage unit 21.32 --

According to the calculation result of Table 2.3.1, the daily output of dried biogas


Project Analysis

dregs is 21.32t. See Diagram 2.

Diagram 2 Material (TS) Balance Diagram

A: Remove 0.90t sand per day B: produce 54.78t biogas per day C: produce 7.03t

biogas per day D: homogenate basin E: anaerobic jar F: 1# biogas liquid

after-fermentation tank G: rinsing water H: proliferate 7.76t microorganism per day I:

liquid organic fertilizer J: biogas liquid tank K: solid-liquid separation L: solid

organic fertilizer

The water content of biogas dregs is 65%. The daily output of dried biogas dregs is

21.32t, and the daily output of biogas dregs is 60.91t.

The mass of excrement resource decreases after the pretreatment and anaerobic

digestion. See Table 2.3.2 for the calculation. From the table, we can see that the

decrease rate is 66.5%.

Table 2.3.2 Calculation of Decrease Level

Mass of dried

excrement

(t/d)

Mass of

removed

dried material

(t/d)

Mass of dried

biogas dregs

(t/d)

Mass of dried

biogas

liquid

(t/d)

Decrease (t/d) Decrease rate

(%)

100 0.90 21.32 11.25 66.53 66.50

L

K J11.25 t/d

21.32 t/d

100 t/d

G

99.1 t/d D E

BA C

F 39.60t/d

H 32.57 t/d

11.25 t/dI


Project Analysis

2.3.3 Water balance

1. Water balance calculation

The sewage amount of this project is 1,000t per day, among which 330t is used for

chicken excrement blending, the other 670t is after-fermented directly. See Diagram 3

and Table 2.3.3 for the relationship between water consumption in each processing

unit and total water balance.

Diagram 3 Water Balance Diagram

N

M L

662.95 t/d

39.59

330

H

727.90

E F

A B

G

C

705.40 t/d

670 t/d

K

1332.47

J

D

669.52 t/d

1000 t/d

702.54 t/d

I

A: remove 2.1t sand per day B: produce 22.50t biogas per day C: produce 2.86t biogas per day D:

water collection tank E: homogenate basin F: anaerobic jar G: 1# biogas liquid after-fermentation

jar H: chicken excrement contains 400t water per day. I: produce 0.48t biogas per day J: 2#

fermentation jar K: liquid organic fertilizer L: biogas liquid tank M: solid-liquid separation N:


Project Analysis

solid organic fertilizer

Table 2.3.3 Water Balance Calculation Table

Processing unit Item Amount (t/d) Solid content

Sewage amount 1,000

Excrement

blending 330 Water collection

tank

After-fermentation

jar treatment 670

--

Dried material 100.00

Water amount 730.00

Removed dried

material 0.90

Water consumed in

removing dried

material

2.10

Water content of

chicken excrement400.00

Supplemented

water amount 330.00

Homogenate

sand basin

Water output 727.90

12.0%

Anaerobic

reaction

Consumed in

anaerobic

consumption

22.50 6.6%


Project Analysis

Output after

anaerobic

consumption

705.40

Consumption 2.86 1# biogas liquid

after-fermentation jar Output 702.54 5.7%

Consumption 0.48 2# sewage

fermentation jar Output 669.52 --

Water input for

solid-liquid separation 702.54

Solid-liquid

separation Water output after

solid-liquid separation 702.54

--

Water content of

biogas liquid 662.95

Sewage input 669.52

Biogas liquid

storage

Output 1,332.47

1.6%

Biogas dregs

storage

Water content of

biogas dregs 39.59 35.0%

2.3.4 Overall balance

See Table 2.3.4 for the overall balance of water and material (TS) of this project. The

output of biogas liquid is 1343.72 t/d, containing 1332.47t water and 11.25t dried

material, with the solid content being 1%.

Table 2.3.4 Overall Balance of Water and Material (TS)

Item Water (t/d)

Dried

material

(t/d)

Total Processing unit


Project Analysis

Input 1,400.00 100.00 1,500.00

-- -- -- Water

collection tank

2.10 0.90 3.00 Homogenate

basin

22.50 59.50 82.00 Anaerobic

process

-- -- -- Solid-liquid

separation

2.86 7.03 9.89

1# biogas liquid

after-fermentation

jar

0.48 -- 0.48

2#

fermentation

jar

39.59 21.32 60.91 Biogas dregs

storage

Unit output

1,332.47 11.25 1,343.72 Biogas liquid

storage

Total output 1,400.00 100.00 1,500.00

2.3.4 Calculation of energy conversion of CHP generator

1. Electric power conversion calculation

This system produces 30,000 m3 per day. According to the calculation based on

conversion rate in the actual operation, every m3 of biogas can generate 1.8kWh

electric power, so the daily energy output is: 30,000×1.8 = 54,000 kWh.

2. Calculation of conversion of thermal energy of residual heat system

Recovery of exhaust heat of each generating set: according to the calculation based on


Project Analysis

every m3 of pure methane generating 3kWh power and air fuel ratio being 15:1, the

total gas (gas and air) consumption of generating set whose normal power is 420kW is:

420÷3×（15+1）＝2240m3/h. According to the calculation based on the average

weight being 1.25kg/m3, the total weight of exhaust fume: 2240×1.25＝2800kg/h.

The specific heat capacity of exhaust fume, 0.27kcal／(kg·℃), is calculated

according to the flue gas. Assuming that the temperature of exhaust fume is 550℃,

the available exhaust heat is (550-170)×0.27×2800＝287,000kcal/h.

According to the calculation, the heat of one 500GF1-1RZ gas generating set

available through needle tube heat exchanger is 287,000kcal/h (amounting to 333kW),

so the available exhaust heat of six 500GF1-1RZ gas generating sets per hour is

287,000kcal/h×6＝1,722,000kcal/h (amounting to 1,998kW).

3. Calculation of balance of supply and demand of heat energy

The heating of material is an important condition for the middle-temperature

anaerobic digestion. In order to ensure the digestion tank operates normally in the

38� condition, the material needs to be heated. There is 500t chicken excrement to be

prepared into 830t reacting material whose solid content is 12% every day, and 330t

rinsing water is needed per day. According to the local air temperature, assume that

both the chicken excrement temperature and the sewage temperature are 5�in the

coolest month. Assuming that the specific heat capacity of fecal sewage is equivalent

to that of fresh water, considering the heat loss and increasing the temperature of the

above material by 40�, the needed heat quantity is: 830×1000× (40-5) = 2.905×107

kcal, which can be supplied with the residual heat of generator. In winter, the heat

needed to heat the feed of anaerobic jar is 2.905×107kcal÷24=1,211,000 kcal/h. And

the remaining heat is 1,722,000－1,211,000＝511,000 kcal/h (amounting to 594kW).

Therefore, the area of hencoop heated with remaining heat: 594×1000÷50＝

11880m2 (assuming that heating of every square meter needs 50W).

In summer, the residual heat of generating sets can all be used to cool the hencoop

(late-phase project). Assuming that the thermal coefficient of lithium bromide

refrigerating unit is 1.39, the refrigerating capacity is: 1,722,000kcal/h×1.39＝

2,393,600kcal/h (amounting to 2,783kW), so the hencoop refrigeration area is: 2,783


Project Analysis

×1,000÷30＝92,767m2 (assuming that the refrigeration of every square meter needs

30W).

III. Analysis of Pollution-Preventing Measures

3.1 Prevention of exhaust gas pollution

The waste gas of this project mainly comes from the fume of the biogas generating set

and the foul gas produced during hydrolysis acidification of the chicken excrement.

3.1.1 Exhaust fume of generating set

The generating set burns the biogas. After purification, the CH4 content in the biogas

reaches 60%, and the H2S content is less than 200mg/l, which meets the requirement

for gas by gas generating set: CH4＞40%, and H2S content＜200ppm.

According to the information provided by the factory, the amount of pollutant in the

exhaust gas discharge of the 500GF1-1RZ biogas generating set is: nitric oxides

0.30g/kWh; SO2＝consumption of fuel gas (m3/d)×H2S content in gas (mg/m3)×

2.857/daily energy output (kWh/d)＝ 0.32 g/kWh. The daily energy output is

54,000kWh, so the exhaust gas of the generating set can be calculated as Table 3.1.2:

Table 3.1.2 Exhaust Emission Table

Exhaust gas amount (10,000 m3/a)

SO2 NOX

(t/a) mg/m3 (t/a) mg/m311,773

6.3 53.5 5.9 50.1

The exhaust emission is in line with the Class Two standard of Table 2 of Integrated

Emission Standard of Air Pollutants (GB16297-1996) (Because the exhaust emission

standard for biogas generating set hasn’t been issued in China, the above standard is

implemented.)

The generating set has one exhaust mast, which is set 10.5m above the roof of power

house (4.5m high), with the overall height being 15m and inside diameter of outlet

being 0.45m. According to the relevant regulations of Integrated Emission Standard of

Air Pollutants concerning the height of newly established exhaust mast, the exhaust

mast shall be no less than 15m high, and the exhaust mast of newly established project


Project Analysis

shall be at least 5m higher than the highest construction within 200m away from the

exhaust mast, or the emission standard 50% stricter than the emission rate

corresponding its height shall be implemented. The highest construction within 200m

away from the generator room is 5m in height, so the height of exhaust mast reaches

the standard requirement.

3.1.2 Foul gas

The exhaust gas produced in this project is mainly the foul gas produced during the

operation of each excrement treatment unit, which is mainly composed of hydrogen

sulfide and ammonia etc. Apart from the pretreatment, other working procedures, such

as anaerobic digestion, are carried out in the sealed jar, so the foul gas will not have

influence on the environment. In the pretreatment procedure, there are grille water

collection tank and homogenate sand basin, which are closed with cover. In addition,

the pretreatment room has the biological deodorization device to remove the stench.

However, the biogas liquid storage basin is open mouthed, so the gas emission is

unavoidable. In order to prevent the stench pollution, the protective green belt is set

for isolation, the basin emitting high-value odor is screened with production building,

the plant is fully greened, and the protective isolated area is set in different sections.

All these measures can effectively reduce the influence of odor on the ambient

environment. Through the above measures, it can meet the limit as regulated in Class

Two standard of Emission Standard for Odor Pollutants (GB14544-2001).

3.2 Prevention of sewage pollution

3.2.1 Factory sewage disposal The biogas engineering of this project processes 365,000t sewage every year, which is

mainly the rinsing water of the animal farm of the company, and produces 490,000t

liquid organic fertilizer, biogas liquid. Each generating set of the generation

engineering makes cycling use of 40t water per hour, with 12t fresh water

supplemented per day. The water for residual heat utilization system is enclosed and

circulated.

The drain water produced in the production is biogas liquid, the raw material of

organic fertilizer. Its output is 1,343.72 t/d, among which the water content is


Project Analysis

1,332.47 t/d, and the dried material content is 11.25t/d, with the solid content being

1.6%. The annual output is 490,000t, which is used as organic fertilizer for farmland:

● In the farming and fertilization season, the biogas liquid is conveyed to biogas

liquid storage tank, orchard, nursery, and farmland etc. (through pipeline and

sealed tank car) as liquid organic fertilizer.

● Out of the farming and fertilization season, the biogas liquid is conveyed and

stored in the biogas liquid storage tank for future use.

Sulfurous acid, product from biological desulfurization, can be returned to the biogas

liquid to keep the nutritive equilibrium of biogas liquid as organic fertilizer.

3.2.2 Domestic sewage disposal

The domestic sewage of this project is collected through the sewage pipeline network

of the plant, and enters the water collection tank for treatment.

3.3 Prevention of noise pollution

The noise source of this project mainly includes pump, blower, cooling tower and

heat exchanger of biogas generating set. The noise reduction measures to be adopted

include:

Blower: install noise eliminator and blast deflector in the air absorption inlet to

reduce the noise and remove the vibration resulting from airflow. Besides, the

acoustic enclosure is set to reduce noise. Number: 2, laid indoors; source intensity:

85～90dB(A).

Heat exchanger: install muffler; lay it indoors; source intensity: 85 dB(A).

Water pump and cooling tower: adopt the low-noise equipment, adopt anti-vibration

measures for the pump foundation, and lay it indoors; source intensity: 75～80 dB(A).

Apply plastic cement washer at the bottom of cooling tower, and arrange fine-meshed

nylon net on water surface to reduce the water spraying noise, and lay it on the roof;

source intensity: 75 dB(A).

It is estimated that with the door and window closed, the influence of noise on the

plant can meet the requirement of ClassⅡstandard.

3.4 Prevention of solid waste pollution


Project Analysis

3.4.1 Production solid waste

This biogas engineering project processes 182,500t fresh excrement every year. The

water content of produced biogas dregs is 65%, the output of biogas dregs is 60.91 t/d

(TS 35%), and the output of dried biogas dregs is 21.32t/d. After the dehydration in

Phase Two project, it will produce 10,376t biogas dregs (TS 75%) whose water

content is lower than 25%. After reaching the requirement of Standard for Biological

Organic Fertilizer (NY884-2004), it will be sold as organic fertilizer for farmland. 0.9t

sand and excrement dregs are produced per day in the homogenate sand basin, which

will be transported to be buried in Penglai innocent garbage disposal plant. The sulfur,

product from biological desulfurization, can be recovered and sold.

3.4.2 Domestic garbage

There is about 2.8t domestic garbage/a, which is cleared and transported and treated

by the local environmental sanitation department.

3.5 Influence of electromagnetic radiation

The output line of this project coincides with the input line of the former project,

mainly passing through mountainous areas and farmland, keeping away from villages.

And it adopts 10KV voltage for transmission, which will not affect the local residents.

3.6 Conclusion

To sum up, in order to have the emission meet the standards and prevent pollution, the

construction unit is suggested to adopt further measures, which are to put biological

deodorant at the passage of the carrier vehicles, to set water jet pump and spray gun,

to rinse the residue at the bottom of vehicle and in the tank with activation solution, to

clean the vehicle, and to spray the vehicle upon its arrival.


Project Analysis

Chapter Two Alternative Proposal

Evaluation


Project Analysis

I. Comparison between Implementing and not Implementing the Project

This program analysis focuses on the comparison about the influence on the

environment between implementing and not implementing the project from the angle

of environment improvement.

Program One: biogas engineering project for excrement treatment and resource

utilization

Program Two: no activity and no project

See Table 1 for the merits and demerits of the above two programs.

Table 1 Comparison between Implementing and not Implementing the Project Program One Program Two S/N

Through anaerobic fermentation, the chicken excrement produces a large amount of quality biogas, which is used for power generation. The electric power is integrated into the power grid and sold, which can bring considerable economic benefits. Through the anaerobic fermentation, the chicken excrement can produce 30,000 m3 per day, which can be used to generate 54,000kWh electricity per day. Assuming the electricity rate is 0.594Yuan/kWh, it can bring the revenue of 11.70774 million Yuan every year.

None

1

2

Reduce the emission of greenhouse gasses and recover the waste. Through the anaerobic fermentation, the chicken excrement can produce 10,376t biogas dregs (TS 75%) and 490,000t biogas liquid, which can be used as high-analysis organic fertilizer. It not only reduces the production costs of directly producing organic fertilizer with chicken excrement, but also such high-analysis fertilizer has the disease and insect-proof function. Such fertilizer cannot only increase the yield, but also can be used to produce environment-friendly and nuisance-free farm products to increase the

Maintain the present situation: much far from the state environmental protection requirement.


Project Analysis

quality of farm product. It realizes the clean production and zero discharge of waste of domestic animal and poultry. It can reduce the discharge of 104,682t equivalent weight of CO2 and bring remarkable environmental benefit. Comply with the requirement of the overall plan of Minhe, promote the excrement treatment level, and enhance the sustainable development ability

Maintain the present situation: influence the future development of the company.

3

Improve the excrement treatment problem, promote the living quality of local residents, and facilitate the development of social relations.

Maintain the present situation: If it continues this way, it may influence the relationship between the Party and the local residents, which is not good for the stable development of society.

4

A little dust, drain water, noise, and solid waste are produced in the construction period, which destroys the vegetation and causes soil erosion; Temporarily increase the traffic pressure and destroy the landscape of construction site.

None

5

The new construction occupies some land permanently, and thus changes the utilization manner of such land.

None 6

From Table 1-1, we can see that after the implementation of Program One, though it

has certain influence on the environment during the project construction and operation,

such influence is limited in time or space, which can be eliminated or reduced to the

minimum through all kinds of measures and will not exert large unfavorable influence

on the regional environment. In addition, with the implementation of Program One,

the reduction and innocent treatment of the chicken farm waste, as well as turning it

into resource, are very promising and have active social benefit, ecological benefit

and economic benefit. After the establishment of this project, its sewage discharge

will reach the standard, and it will improve the regional ecological environment,

enhance the quality of people’s living environment, and promote the local sustainable

development, which meets the willing of the public. Therefore, according to the

assessment, it’s reasonable to implement this project.

II. Factory Site Selection


Project Analysis

2.1 Principle for Site selection

Apart from considering the overall plan of the company and the excrement

distribution, the following principles shall be observed:

The factory site selection should make the wastewater system layout

economical and reasonable;

Conform to the overall plan of the city;

Try to select the place not threatened by the flood;

Give priority to place of good geologic setting, low ground water level, and

large bearing capacity of foundation to reduce the costs as far as possible and

facilitate construction;

Around the factory site, there should be good sanitary environment to

facilitate the setting of protective belt;

Consider the transportation condition and water and electricity supply etc.

The planned land has sufficient construction and development space, does not

occupy or occupies less fertile land, and has land for future expansion;

Keep sufficient distance from village and residential area to avoid or reduce

the influence on society as much as possible.

2.2 Comparison on and selection of factory site

The breeding farms of Shandong Minhe Animal Husbandry Co., Ltd (Minhe hereafter)

are distributed in three areas of Penglai City. So after several discussions with

construction unit and onsite investigation for many times, there are three sites

available for comparison and choice (See Attached Diagram 3 Factory site

Comparison and Selection). The transportation and natural terrain condition of the

three sites are all suitable for the biogas engineering project, but there are limitations

and unfavorable factors in the economic condition. The comprehensive analysis and

comparison are conducted as follows:

Program A: Qujiagou Village, Beigou Town, the most centralized area with the largest

raising amount of the company.

Program B: Western suburb of Penglai City, near the headquarters of the company.


Project Analysis

Program C: Northeast of Penglai City, between Xujia Village and Dazao Village.

Table 2 Comprehensive Analysis and Comparison of Factory Sites

Item Program A Program B Program C

600,000 sets of parent breeding broiler chicken and 3,700,000 commercial broiler chicken

Breeding 300,000 sets of parent breeding broiler chicken.

Breeding 400,000 sets of parent breeding broiler chicken.

Raising scale

Transport capacity Little Less Large

Qujiagou Village, Beigou Tow, about 7.5km away

from the urban area

West suburb of Penglai City, about 2.5km away

from the urban area

Northeast of Penglai City, between Xujia Village and Dazao Village

Geographic location

Lie in the lowest place, 2km away from the northernmost of this raising area, with the drop height being 16m, and 0.6km away from the southernmost of the area, with the drop height being 2m. It is favorable for the natural flow of sewage of the whole raising area so as to centralize sewage.

The cultivation farm is decentralized, and the

sewage can’t be centralized through

natural flow.

The cultivation farm is decentralized, and the

sewage can’t be centralized through

natural flow.

Terrain

Around it is wood land and farmland.

Around it is woodland and farmland.

Around it is wood land and farmland. And it is about 2km away from the Yellow Sea in the

north.

Ambient environment

Relocation of residents None None None

Water and electricity supply condition

Good Good Good

Distance from the nearest residential area

800m 600m 700m

Lie in the leeward of the predominant wind direction of city, so the stench will not

influence the urban area.

Lie in the leeward of the predominant wind

direction of city, so the stench will not influence

the urban area.

Not lie in the predominant wind

direction of city, so the stench will not

influence the urban area.

Wind direction

Plan

Conform to the plan of the company and Penglai City and have the reserved place

of the company.

Neighboring the urban area, it will be moved to new place in the future.

Neighboring the economic and technological

development area, it will be moved to new

place in the future.


Project Analysis

Favorable for centralized management

Unfavorable for centralized management

Unfavorable for centralized

management Management

Program A is more economical and reasonable than Program B and Program C. Conclusion

From Table 2-1, we can see that Program A is more economical and reasonable than

Program B and Program C in every aspect. It conforms to the company’s overall plan

and the policies for local atmospheric pollutant prevention and the protections of

water resource, environment, natural landscapes, famous scenic sites, and cultural

relics. And this location will occupy no farmland or woodland, nor will there be any

need to relocate residents, so Program A is adopted for the factory site selection.

III. Comparison on Technological Process

3.1 Comparison and selection of anaerobic technique

3.1.1 Description of technical performance of all kinds of anaerobic reactors

1) Continuous stirred tank reactor (CSTR)

CSTR is suitable for the anaerobic digestion of sludge and high-solid-content organic

wastewater of urban sewage disposal plant. It can adopt single-stage digestion or

two-stage digestion. The single-stage digestion should adopt the middle temperature

or normal temperature. For the two-stage digestion, provided that the temperature of

material liquid is enough, the first stage should adopt the high-temperature digestion,

and the second stage should adopt the middle-temperature digestion. The effective

volume of CSTR should be determined according to the hydraulic residence time or

volume load. See Table 3 for the design parameters of some kinds of common

fermentation material for CSTR.

Table 3 Relevant Parameters of CSTR

Normal temperature (15~25℃) Middle temperature (35~38℃) Raw

material Hydraulic residence

time Volume load

Hydraulic

residence time Volume load

Pig

excrement 20~40 d 1.0~2.0 kgTS/(m3·d) 15 d

3.0~4.0

kgTS/(m3·d)


Project Analysis

liquid

20~60 d 1.0~2.0 kgTS/(m3·d) 15 d

3.0~4.0

kgTS/(m3·d)

Chicken

excrement

liquid

20~60 d 1.3~2.0 kgTS/(m3·d) 15 d

3.0~4.0

kgTS/(m3·d)

Cattle

excrement

liquid

Alcohol

waste water 6~15 d

3.0~5.0

kgCOD/(m3·d)

The cycle of circulating working procedures, such as charge, discharge, blending, and

idling of CSTR, as well as the running time of each working procedure, should be

determined according to the property of fermentation material, digestion temperature,

and effluent water quality requirement. The intermittent agitation equipment should

be able to agitate the material liquid in the reactor at least once within 5-10h. It adopts

the agitation and heating technology in the biogas fermentation jar, which is a major

breakthrough for the biogas fermentation technique. The agitation and heating greatly

increase the biogas fermentation rate, so CSTR is also called high-velocity biogas

fermentation jar, which is characterized by high solid concentration, with TS being

6-12%, enabling the biogas fermentation treatment for all domestic animal excrement.

Its merits include large processing capacity, large biogas output, convenient

management, easy startup, and low transportation fees. It is generally suitable for the

area that mainly produces biogas and where the liquid organic fertilizer (water manure)

is used widely. Because this technique is suitable for treating the high suspended

matter content animal excrement and organic waste and has merits incomparable by

other high-efficiency biogas fermentation technique, it is widely used in such areas as

Europe, where the biogas engineering is very developed.

2) Anaerobic contact reactor

The anaerobic contact technique is suitable for treating the organic wastewater of high

suspended matter concentration and high organic matter concentration. The volume of


Project Analysis

anaerobic contact reactor should be calculated according to the organic volume load

or hydraulic residence time. In the condition of middle temperature or near middle

temperature, the volume load should better be 2.0~5.0 kgCOD/m3·d, or should be

determined according to the type and property of fermentation material, and the

required treatment degree, or the test and the actual operation data of anaerobic

digestion engineering of similar raw material. The return sludge amount is determined

according to the sludge amount in the reactor, feed pH and temperature, which should

better be 50%~200%.

The anaerobic contact reactor is the completely mixing-type reactor. The mixed liquid

discharged from the reactor first goes through the solid-liquid separation in the

sedimentation basin. The sewage is discharged from the upper part of the

sedimentation basin, while the sludge in the lower part of the sedimentation basin is

returned to the anaerobic digestion basin. Such technological process not only ensures

that the sludge is not drained, but also promotes the sludge concentration in the

anaerobic digestion basin, and thus promotes the organic load rate. In comparison

with the common anaerobic digestion basin, it reduces the hydraulic residence time.

Currently, the completely mixing-type anaerobic contact reactor has been used in the

treatment of high-analysis organic wastewater of high SS concentration.

3) Up-flow anaerobic sludge bed (UASB)

UASB is suitable for treating the organic wastewater with the suspended matter

concentration ≤2 g/L. The wastewater to be treated is introduced to the bottom of

UASB, up-flows and passes the flocculent or granular anaerobic sludge bed. With the

contact between sewage and sludge, the anaerobic reaction takes place, and the biogas

thus produced causes the agitation of sludge bed. Part of the biogas produced in the

sludge bed adheres to the sludge grain. The free bubble and the bubble adhering to the

sludge grain flow up to the upper part of the reactor. And the gas-liquid-solid

separation is realized through the three-phase separator in the upper part of the reactor.

The characteristic of UASB is that it can maintain high sludge concentration and high

influent water volume load rate, and thus greatly promotes the processing capacity of

unit volume of anaerobic reactor. But it is not suitable for the fecal sewage of high SS


Project Analysis

content, and the investment cost is high.

The volume design of UASB should be determined according to the volume load. See

Table 4 for the volume load of UASB under the different temperature conditions.

Table 4 Designed Volume Load of UASB under Different Temperature Conditions

Designed volume load (kgCOD/m3·d) Temperature (℃)

High temperature (50~55) 10~20

Middle temperature (35~38) 5~10

Normal temperature (15~25) 2~5

Low temperature (10~15) 1~2

The influent system of UASB may adopt various types, but the following principles

should be observed to ensure the function of water proportioning and hydraulic

agitation: a) ensure the water inflow of each unit area is basically same, i.e. one point

of inflow is set every 2~4 m2; b) spare no effort to meet the requirement of hydraulic

agitation; c) easy to find the influent pipe blocking; d) easy to clear the blocking.

The effluent system is set at the top of USAB. The multi-slot effluent weir should be

adopted. And the scum board should be set between the effluent weirs.

4) Up-flow solid reactor (USR)

USR is a kind of new reactor specially used to treat those of high solid content, whose

characteristic is that no three-phase separator or other components are set in the

reactor.

The up-flow solid biogas fermentation technique is suitable for treating the waste

organic liquid with the solid content (TS) being 3-8%. When the wastewater

containing high-analysis organic solid (TS 3-8%) enters from the water distribution

system at the bottom and flows up and passes the solid bed containing high-analysis

anaerobic microorganism at certain speed depending on the dynamic force from

feeding and gas production, the organic substance is decomposed and fermented and

produces biogas. The biogas thus produced goes up with the water flow has the

function of agitation and blending, which makes the remaining undigested solid

further contact with the microorganism and oxidize, and realizes high removing rate


Project Analysis


and biogas yield finally. When TS is more than 6%, the partial intensified agitation

measures need to be adopted. The volume of USR should be determined according to

the volume load. And the volume load should be determined according to the type and

property of material and the required treatment degree, as well as the digestion

temperature etc. In the middle-temperature or near middle-temperature digestion

condition, it is suitable for the volume load of treating animal excrement to be 3-6

kgCOD/m3·d.

3.1.2 Selection of and decision on anaerobic technique

Mid

dle

tem

pera

ture

or h

igh

tem

pera

ture

Suita

ble

for a

naer

obic

dig

estio

n

of

high

-sol

id

orga

nic

was

te

wat

er. T

he so

lid c

onte

nt (T

S) o

f

feed

is

8~

12%

. In

term

itten

t

feed

is g

ener

ally

ado

pted

.

Mid

dle

tem

p.:

20~3

0 d

Hig

h te

mp.

:

15 d

200~

3000

m3

Hig

h fe

ed

conc

entra

tion,

an

d

high

vo

lum

e ga

s

yiel

d,

com

mon

ly

betw

een

1.5

and

3.0

C

onve

nien

t

man

agem

ent

and

easy

oper

atio

n an

d

mai

nten

ance

Low

lum

p-su

m i

nves

tmen

t co

sts.

The

mai

n op

erat

ion

cost

s co

me

from

feed

ing

pum

p an

d ag

itato

r.

The

inte

grat

ed

use

of

ferm

enta

tion

liqui

d is

requ

ired.

Mid

dle

tem

pera

ture

or h

igh

tem

pera

ture

Suita

ble

for t

reat

ing

the

orga

nic

was

tew

ater

of

high

sus

pend

ed

mat

ter

conc

entra

tion

and

high

orga

nic

mat

ter c

once

ntra

tion

Bas

ical

ly

sam

e as

that

of C

STR

200~

3000

m3

Feed

co

ncen

tratio

n

and

gas

yiel

d ar

e

sim

ilar w

ith th

ose

of

CST

R

Con

veni

ent

man

agem

ent

and

easy

oper

atio

n an

d

mai

nten

ance

Nee

d to

es

tabl

ish

new

sl

udge

sedi

men

tatio

n ba

sin

& r

eflu

x un

it,

whi

ch

incr

ease

s th

e in

vest

men

t.

The

mai

n op

erat

ion

cost

s co

me

from

fee

ding

pum

p, a

gita

tor,

and

slud

ge re

flux

pum

p et

c.

The

inte

grat

ed

use

of

ferm

enta

tion

liqui

d is

requ

ired.

peci

al C

hapt

er fo

r Pro

ject

ana

lysi

s

Shan

dong

Aca

dem

y of

Env

ironm

enta

l Sc

ienc

e

Tabl

e 5

Com

paris

on o

n M

ain

Para

met

ers a

mon

g th

e Fo

ur A

naer

obic

Te

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