Boiler System

Date: 06/06/2017

By Wasiullah

BOILER:

A boiler is defined as "a closed vessel in which water or other

liquid is heated, steam or vapor is generated, steam is

superheated, or any combination , under pressure or vacuum,

for use external to itself, by the direct application of energy

from the combustion of fuels, from electricity or nuclear

energy."

Types of Boiler:

1) Fire Tube Boiler

2) Water Boiler

Fire Tube Boiler:

The fire tube boiler design uses tubes to direct the hot gases

from the combustion process through the boiler to a safe point of

discharge. The tubes are submerged in the boiler water and

transfer the heat from the hot gases into the water.

Types of fire-tube boiler

• Cornish boiler.

• Lancashire boiler.

• Scotch marine boiler.

• Locomotive boiler.

• Vertical fire-tube boiler.

• Horizontal return tubular

boiler.

• Immersion fired boiler.

• Cornish boiler :Cornish boiler is a simple horizontal

boiler which belong to the shell and tube

class of boilers. Cornish boiler is much like

the Lancashire boiler. Cornish boiler has the

ability to produce steam at the rate of 1350

kg/hr and can take the maximum pressure of

about 12 bar. Dimensions of the Cornish

boiler shell is 4 m to 7 m in length and 1.2 m

to 1.8 m in diameter.

• Lancashire boiler:The Lancashire boiler is similar to the

Cornish, but has two large flues containing

the fires instead of one. It is generally

considered to be the invention of William

Fairbairn in 1844, although his patent was

for the method of firing the furnaces

alternately, so as to reduce smoke, rather

than the boiler itself.

• Scotch Marine Boiler:

The Scotch Marine Boiler is a

fire-tube boiler, in that hot flue gases

pass through tubes set within a tank

of water. The general layout is that of

a squat horizontal cylinder. One or

more large cylindrical furnaces are in

the lower part of the boiler shell.

Above this is a large number of

small-diameter fire-tubes.

• Locomotive boiler:

Locomotive boiler is the horizontal

fire tube boiler in which hot gases pass

through the tubes and water surrounds

them. Transferred heat from the gases

to water and then converted into

steam. It may also be used as a

stationary boiler.

• Vertical fire-tube boiler :A vertical fire-tube boiler or vertical

multitubular boiler is a vertical boiler where

the heating surface is composed of multiple

small fire-tubes, arranged vertically. These

boilers were not common, owing to

drawbacks with excessive wear in service.

The more common form of vertical boiler,

which was very similar in external

appearance, instead used a single flue and

water-filled cross-tubes.

• Horizontal return tubular boiler:

A fire-tube boiler is a type of boiler in

which hot gases from a fire pass through

one or (many) more tubes running through a

sealed container of water. The heat of the

gases is transferred through the walls of the

tubes by thermal conduction, heating the

water and ultimately creating steam.

• The immersion fired boiler:

The immersion fired boiler is

a single-pass fire-tube boiler that

was developed by Sellers

Engineering in the 1940s. It has

only firetubes, functioning as a

furnace and combustion chamber

also, with multiple burner nozzles

injecting premixed air and natural

gas under pressure. It claims

reduced thermal stresses, and

lacks refractory brickwork

completely due to its construction

Water Tube Boiler:

The water tube boiler design uses tubes to direct the

boiler water through the hot gases from the combustion

process, allowing the hot gases to transfer its heat through the

tube wall into the water. The boiler water flows by convection

from the lower drum to the upper drum.

Types of Water Tube Boiler:

• Horizontal Straight Tube Boiler.

• Bent Tube Boiler.

• Cyclone Fired Boiler

Burner is a mechanical device that burns a gas or liquid fuel

into a flame in a controlled manner.

Energy Efficient Burner:

An efficient burner provides the

proper air-to-fuel mixture

throughout the full range of firing

rates, without constant adjustment.

Many burners with complex linkage

designs do not hold their air-to-fuel

settings over time. Often, they are

adjusted to provide high excess air

levels to compensate for

inconsistencies in the burner

performance.

BURNER

Energy Saving Due to Installation of an Energy Efficient Burner

Burner Combustion

Efficiency Improvement %

Annual Energy Savings

(MMBtu/year)

Annual Savings ($)

1 6,250 28,125

2 12,345 55,550

3 18,290 82,305

Cost Savings = Fuel Consumption * Fuel Price * (1-E1/E2)

If the installed cost is $50,000 for a new burner that provides an

efficiency improvement of 2%, the simple payback on Investment is:

Simple Payback = $50,000 ÷ $55,550/ year = 0.9 Years

Example;

Even a small Improvement in burner efficiency can provide significant

savings. Consider a 50,000 pound per hour process boiler with a combustion

efficiency of 79% (E1). The Boiler annually consumes 500,000 million British

thermal units(MMBtu) of natural gas. At a price of $4.50/MMBtu, the annual

fuel cost is $2.25million. What are the saving from installing an energy

efficient burner that improves combustion efficiency by 1%, 2%, or 3 %.

• Perform burner maintenance and tune your boiler.

• Conduct combustion-efficiency tests at full- and part-load

conditions.

• If the excess O2 exceeds 3%, or combustion efficiency values are

low, consider modernizing the fuel/air control system to include

solid-state sensors and controls without linkage. Also consider

installing improved process controls, an oxygen trim system, or a

new energy-efficient burner.

• A new energy-efficient burner should also be considered if repair

costs become excessive, reliability becomes an issue, energy

savings are guaranteed, and/or utility energy-conservation rebates

are available.

• Install a smaller burner on a boiler that is oversized relative to its

steam load.

SUGGESTED ACTIONS

• Air Properties:

For a burner originally adjusted to 15 % air, changes in

combustion air temperature and barometric pressure cause the

following in excess air:

Expressed as a percent of the stoichiometric

air required.

PASSES OF BOILERS

Three-pass firetube boiler:

A 3-pass firetube boiler design

consists of three sets of horizontal

tubes, with the stack outlet

located on the rear of the boiler. A

downdraft design keeps the cooler

water from having an effect on

the hot surfaces within the boiler.

3 pass firetube boilers offer:

• maximized heat transfer

• minimal refractory

• high steam/water storage

• effective handling of wide

load demands

Four-pass boiler:

A four-pass boiler design consists

of four sets of horizontal tubes, with

the stack outlet at the front of the

vessel. A downdraft design keeps the

cooler water from having an effect

on the hot surfaces within the boiler.

4-pass boilers leverage natural draft

operation which allows cool water to

contact the hottest part of the boiler.

4 pass firetube boilers offer:

• maximized heat transfer

• minimal refractory

• high steam/water storage

• effective handling of wide

load demands

BOILER PERFORMANCE TEST

Performance of the boiler, like efficiency and evaporation ratio

reduces with time, due to poor combustion, heat transfer fouling and

poor operation and maintenance. Deterioration of fuel quality and

water quality also leads to poor performance of boiler. Efficiency

testing helps us to find out how far the boiler efficiency drifts away

from the best efficiency.

• To find out the efficiency of the boiler

• To find out the Evaporation ratio

The purpose of the performance test is to determine actual

performance and efficiency of the boiler and compare it with design

values or norms. It is an indicator for tracking day-to-day and season-

to-season variations in boiler efficiency and energy efficiency

improvements

1. Boiler Efficiency = Heat Output/Heat Input*100

= Heat In Steam Output(kCals)/Heat in fuel Input(kCals)*100

2. Evaporation Ratio = Quantity of Steam Generation/Quantity of Fuel Consumption

Heat recovery equipment is available to preheat feed water

entering the boiler (economizer) and to capture Btu’s lost

through boiler blowdown (blowdown heat recovery or flash

tank heat exchangers). Such equipment is normally used on

installations where boiler size, operating pressures or the

amount of water make-up justify the economics for the

purchase and installation costs (normally units exceeding

100 hp and operating at 100 psi or more). Maintenance

costs also must be considered before a decision is made for

their installation.

HEAT RECOVERY EQUIPMENT

Economizers are bent, finned-tube heat

exchangers. They are available in

rectangular or cylindrical styles. The

type of boiler and the overall boiler

room layout may dictate which style is

utilized.

The products of combustion leaving the

boiler flow through the economizer,

over the finned tubes, transferring its

heat or Btu’s to the boiler feed water.

The efficiency of the overall system can

be increased By 2% to 4%, depending

on fuel being burned, boiler size, and

operating conditions.

ECONOMIZERS

There are several methods and

equipment used in blowdown heat

recovery.

In most cases, the systems are used on

continuous or surface blowdown to

control the Total Dissolved Solids

(TDS) in the boiler water.

Blowdown heat recovery equipment

is used for automatic control of the

continuous blowdown, based on

water make-up and cools the

continuous blowdown to a point

where it can be safely dumped to the

sewer system. It transfers heat or

Btu’s to the make-up water, thus

raising the temperature of the make-

up water before it enters the deaerator

or boiler feed system.

BLOWDOWN EQUIPMENT

An additional piece of equipment, the

blowdown separator , can be installed for

bottom blowdown. The blowdown

separator reduces the temperature of the

bottom blowdown water to a temperature

that would be safe for the sewer system.

However, because of the erratic flow of

bottom blowdown, there is little benefit to

use a blowdown separator as a means to

raise the temperature of make-up water

prior to entering the deaerator or boiler

feed system.

BLOWDOWN SEPARATOR

Another system uses the

addition of a flash tank heat

exchanger. This system works

on the same principle as the

blowdown heat recovery

system, however, it also

provides the benefit of flash

steam. This flash steam can be

reused in the plant, such as

being piped to a deaerator and

mixed with the incoming steam

in the deaerator.

FLASH TANK HEAT EXCHANGER:

During daily operation of a plant, a

sample cooler is normally required to

draw samples of boiler water, so

chemical tests can be performed. The

boiler water, however, is above the

temperature that test equipment can

handle. In most cases, the situation is

resolved with the installation of a

sample cooler.

SAMPLE COOLER

Boiler feed water usually contains two

harmful dissolved gases: Oxygen and

Carbon Dioxide. If the dissolved gases are

not removed before entering the boiler, they

will be liberated by heat and may cause

severe corrosion in the boiler, steam lines,

condensate lines, and heat transfer

equipment, which can prove to be very

costly. The dissolved oxygen and carbon

dioxide can be removed with chemicals.

Depending on the overall system, it may not

be practical to chemically remove the

dissolved oxygen and carbon dioxide from

the feed water. In these cases, a deaerator

should be installed. Because the deaerator

mechanically removes dissolved oxygen

and carbon dioxide, the amount of

chemicals required could be reduced.

BOILER FEEDWATER EQUIPMENT

The deaerator is a pressurized

American Society of Mechanical

Engineers (ASME) tank and may be

the largest piece of auxiliary

equipment in the boiler room. A

deaerator is designed to heat water to

the temperature of saturated steam at

the pressure within the deaerator.

A deaerator provides an effective

means for recovery of heat from

exhaust or flash steam, provides a

location for returning condensate and

accepts condensate first to reduce

excessive make-up water. There are

three types of deaerators available.

The tray type is normally used in

large utility plants.

DEAERATORS

If plant conditions do not warrant the use of a deaerator, in most cases, a

Packaged Feed System is used. The packaged feed system is an atmospheric

tank that can heat feed water to a maximum of 210°F.

Because they are atmospheric tanks, they are equipped with an epoxy lining

or made from galvanized steel. The packaged feed system heats the feed

water and reduces the amount of dissolved oxygen and carbon dioxide in the

feed water.

There are many additional pieces of

equipment available to remove

impurities in the make-up water before it

enters the boiler and system. The type of

equipment required is determined by a

water analysis. This equipment can be

classified as pre-treatment equipment.

FEED SYSTEMS

Filters are available to remove

free chlorine, some dissolved

organics and sediment. They can

also remove suspended solids,

colloidal matter, sand and iron.

There are carbon filters,

multilayered filters, sand or iron

filters. There can be lined tanks,

American Society of Mechanical

Engineers (ASME) code tanks

and automatic operation based on

a time clock, pressure differential

switch or water meter. They can

protect such items as water

softeners, dealkalizers, and

reverse osmosis equipment, etc.

PRE-TREATMENT EQUIPMENT:

A surge tank could be used under the

following conditions: If there are

intermittent peak loads of condensate

that can exceed the surge capacity of

the deaerator - varying pressures or

temperatures in condensate – gravity

or pumped condensate that have

insufficient pressure to enter the

deaerator on their own. Surge tanks

are atmospheric and accept condensate

and make-up water before it goes to

the deaerator. Surge tanks can be lined

with an epoxy coating to prevent

corrosion. The condensate and make-

up water mix into a blend temperature

as determined by the percentage of

each.

SURGE TANK

The Flame Safeguard or Programming

Control on boilers are designed to ensure that

the start-up of the burner follows a definite

timed sequence of operation. In addition to

the sequence of operation and after the flame

has been established, the Flame Safeguard

monitors the flame and sets the firing rate of

the burner, as determined by the boiler firing

rate controls.

They also monitor, through the boiler controls, items such as boiler pressure or

temperature, fuel pressure or temperature and they provide for normal shut down of

the burner if the load demand is satisfied, or shut down and alarm if there is a safety

shut down condition.

The Flame Safeguards or Programming Control installed on a boiler can be

classified into three categories:

o Electro Mechanical

o Solid State Electronic

o Micro Processor

FLAME SAFEGUARD EQUIPMENT

The electro mechanical controls have been used from around 1950 until

1984.

Solid state electronic controls were introduced in 1984. This type of control

provides for more alarm or monitoring functions than the electro mechanical

controls. The micro processor controls introduced in 1989 not only provide

the functions as the other controls, but also have the ability to send

information to computers and work in conjunction with some energy

management systems. The micro processor type of controls are standardly

furnished on some of today’s modern boilers.

Solid state electronic controlsElectro mechanical controls

After the initial inspection is completed, the new boiler is ready for

startup. Startup can be the most critical period in the life of the

boiler.

1. Steam piping, blow off and blowdown lines, etc. must be

inspected and ready for operation. All piping must be inspected

for adequate support and expansion provisions.

2. All fuel supply lines must be checked for tightness and leaks.

Strainers are most important to the safe operation of gas and/or

oil fired units.

3. Electrical power lines to the boiler/burner unit are connected

and the voltage required is verified.

4. Hydrostatic test has been completed.

5. Any walkways, platforms, stairs, and/or ladders, etc., that are

needed to permit proper access to the boiler/burner, are installed

and ready for use.

BOILER STARTUP

Before the boiler is permitted to go on the line, all of the safety controls

should be checked to make sure they are all operating properly.

Flame Safeguard:

The purpose of the flame safeguard control is to monitor the burner start

up sequence, the main flame and control the firing rate during normal

operation.

Following is a brief step-by-step:

1. The burner switch is turned on or the operating limit pressure (or

temperature) control closes. If all required limit controls are

satisfied, the blower motor starts and the automatic sequence

begins.

2. The programmer actuates the modulating motor and drives it to

high fire position and purges the boiler for a predetermined period

of time.

3. The programmer drives, modulating motor and burner linkage back

to low fire position.

BOILER CONTROLS

4. The ignition transformer is energized and the pilot solenoid

valves are opened. The pilot must light.

5. Trial for ignition period.

6. If the pilot flame is proven, the programmer, after a timed

interval, energizes the main flame fuel valve(s) and trial for

main flame is started, at minimum fuel rate.

7. After a timed period, the main flame has to be established. If

this is completed, the programmer extinguishes the pilot and

then continues to monitor the main flame.

8. The programmer continues to monitor the main flame while the

burner continues to automatically modulate (if the burner is

capable of full modulation) on an increasing or decreasing

firing rate to satisfy the load demand.

9. The programmer cycles to off position and is now ready for

restart upon demand.

1. Know your equipment.

2. Maintain complete records.

3. Establish a regular boiler inspection schedule. The schedule

should include daily, weekly, monthly, semi-annual and annual

inspections or activities.

4. Establish and use boiler log sheets. Log sheets should be tailored

to your equipment.

5. Establish and keep written operating procedures updated.

6. Good housekeeping is a must.

7. Keep electrical equipment clean.

BOILER ROOM CARE

1. Check water level. Ensure there is water in the gauge glass every time

you enter the boiler room.

2. Blow down boiler. Blow down the boiler in accordance with the

recommendation of your feedwater consultant.

3. Blow down the water level controls to purge the float bowl of

possible sediment accumulation. Operating conditions will dictate

frequency of this check.

4. Check combustion visually. Look at the flame to see if something has

changed.

5. Treat water according to the established program. Add chemicals and

take tests as outlined by your chemical feedwater consultant.

6. Record boiler operating pressure or temperature.

7. Record feedwater pressure and temperature.

8. Record stack temperature. Changes in stack temperatures could

indicate the boiler is sooting, scaling or there is a problem with

baffles or refractory.

DAILY MAINTENANCE

9. Record oil pressure and temperature.

10. Record oil atomizing pressure. Changes in pressure could have

an effect on combustion in the boiler.

11. Record gas pressure. Changes in pressure could have an effect

on combustion in the boiler and indicate a problem in the gas

delivery system.

12. Check general boiler/burner operation. Maintaining top

efficiency is the simple and basic reason for having operating

personnel. Is anything different than it was the day before? If so,

why?

13. Record boiler water supply and return temperatures. On hot

water boilers, record these temperatures to assist in detecting

system changes.

14. Record makeup water usage. Excessive makeup water could be

an indication of system problems in both steam and hot water

systems.

15. Check auxiliary equipment.

1. Check for tight closing of fuel valves.

2. Check fuel and air linkages.

3. Check indicating lights and alarms.

4. Check operating and limit controls.

5. Check safety and interlock controls.

6. Check operation of water level controls.

7. Check for leaks, noise, vibration, unusual conditions, etc. Checking

for these items is a cost effective way to detect system operational

changes. Small problems can be corrected before they become

large problems.

8. Check operation of all motors.

9. Check lubricating levels.

10. Check the flame scanner assembly.

11. Check packing glands on all pumps and metering devices.

12. Check gauge glass. Ensure there are no cracks or etching in the

glass or leakage around the packing.

WEEKLY MAINTENANCE

1. Inspect burner operation.

2. Analyze combustion.

3. Check cams. Inspect the cam springs for scoring, tightness of set

screws, free movement, alignment of cam followers and other

related parts.

4. Check for flue gas leaks.

5. Inspect for hot spots. Inspect the boiler to ensure no hot spots are

developing on the outside of the boiler.

6. Review boiler blowdown to determine that a waste of treated water

is not occurring.

7. Check all combustion air supply inlets to the boiler room and burner

to ensure sufficient air is being supplied.

8. Check all filter elements. Clean or replace as needed

9. Check the fuel system to make certain that strainers, vacuum

gauges, pressure gauges and pumps are properly cared for.

10. Check all belt drives for possible failure.

MONTHLY MAINTENANCE

1. Clean low water cutoff . Remove the head assembly or probes and

inspect and clean out any sediment or contamination in the column

or piping.

2. Check oil preheaters by removing the heating element and inspect

for sludge or scale.

3. Repair refractory. Immediately upon opening the fireside areas, give

the refractories an inspection and start repairs as soon as possible.

4. Clean oil pump strainer and filter.

5. Check pump coupling alignment.

6. Reset Combustion. The entire combustion process should be

carefully checked, O2 readings taken and necessary burner

adjustments made.

7. Inspect mercury switches. Inspect mercury switches for

contamination, loss of mercury, and cracked or broken wires.

Replace if any of these conditions are found.

SEMI-ANNUAL MAINTENANCE

1. Clean fireside surfaces by brush or use a powerful vacuum cleaner to

remove soot.

2. Clean breeching. Inspect breeching and stack and remove any soot build

up.

3. Clean waterside surfaces. Remove all hand hole and manway plates,

inspection plugs from water column tees and crosses and float

assemblies from water columns.

4. Check fluid levels on all hydraulic valves. If any leakage is apparent,

take positive corrective action immediately.

5. Check gauge glass for possible replacement. If internal erosion at water

level is noted, replace with new glass and gaskets.

6. Remove and recondition safety valves. Have them reconditioned by an

authorized safety valve facility.

7. If oil fuels are used, check on the condition of the fuel pump. Fuel pumps

wear out and the annual inspection time is the opportune time to rebuild

or replace them.

ANNUAL MAINTENANCE

9. Boiler feed pumps. Strainers should be reconditioned.

10. Condensate receivers should be emptied and washed out. Make

an internal inspection, if possible.

11. Chemical feed systems should be completely emptied, flushed

and reconditioned. Metering valves or pumps should be

reconditioned at this time.

12. Tighten all electrical terminals. All terminals should be

checked for tightness, particularly on starters and movable

relays.

13. Check linkages. Check to ensure the linkage ball connectors

have not worn out. Worn connectors can cause inconstancy in

the linkage movement and result in unrepeatable excess air

levels in the combustion process.

1. The boiler room is for the boiler.

The boiler room should not be considered an all-purpose storage

area. The burner requires proper air circulation in order to prevent

incomplete fuel combustion and production of carbon monoxide.

Therefore, keep the boiler room clean and clear of all unnecessary

items.1.

2. Knowledge is powerful, as are boilers.

Ensure all personnel who operate or maintain the boiler room are

properly trained on all equipment, controls, safety devices, and

up-to-date operating procedures.1.

3. Look for potential problems.

Before startup, ensure the boiler room is free of all possibly

dangerous situations, such as flammable materials or mechanical

or physical damage to the boiler or related equipment. Clear

intakes and exhaust vents; check for deterioration and possible

leaks.

BOILER ROOM GUIDELINES

4. Observe new equipment.

Monitor all new equipment closely until safety and efficiency are

demonstrated.

4. Develop a maintenance schedule.

Use boiler operating log sheets, maintenance records, and

manufacturers’ recommendations to establish a preventive

maintenance schedule based on operating conditions, as well as on

past maintenance, repairs, and replacements performed on the

equipment.

6. Inspection matters.

Ensure a thorough inspection by a properly qualified inspector,

such as one who holds a National Board commission.

7. Reinspection matters, too.

After any extensive repair or new installation of equipment, make

sure a qualified boiler inspector reexamines the entire system.

8. Create thorough checklists.

Establish a checklist for proper startup and shutdown of

boilers and all related equipment according to manufacturers’

recommendations.

9. Don’t overlook automated systems.

Observe equipment extensively before allowing an automated

operation system to be used with minimal supervision.

10. Keep safety at the forefront.

Establish a periodic preventive maintenance and safety

testing program.

STEAM TRAPES

1.) Points about the steam trap

a. Mechanical steam trap

b. (On/Off Operation)

c. Test point – downstream of the discharge orifice

2.) Visual inspection

a. Steam trap should be level to the eye

b. Check flow arrow to insure steam trap is installed correctly

3.) Temperature measurement

a. Take temperatures before and after steam trap

b. Temperatures below 212°F or 100°C, steam trap is not in

operation

c. Take temperature at the process inlet. Temperatures at the process

inlet and the steam trap inlet will be relatively close.

4.) Off position during operation

a. Ultrasound level should be low

or zero on the ultrasound meter

b. Long off periods can cause

“loss of prime”

5.) Discharge Operation (discharging condensate)

a. When the inverted bucket drops due to the loss of buoyancy, this

will bring the valve away from the discharge orifice. This action

will allow the steam trap to discharge the condensate.

b. The ultrasound indicator will rise due to the increase in ultrasound

from the discharge cycle. The ultrasound will stay high or full scale

until condensate is discharged from the steam trap. The ultrasound

level (meter) should deflect more than 30% of scale.

c. When condensate is

completely discharged, the

inverted bucket will rise,

due to buoyancy, and bring

the valve in contact with the

discharge orifice .The steam

trap is now in the off

position. The ultrasound

level should be at zero or

minimum.

d. Ultrasound level should proceed to full or high ultrasound level

during the discharge cycle and return to minimum scale reading or

zero after the discharge is complete.

e. Condensate will crackle and steam will whistle during testing with

the ultrasound equipment, therefore during the cycling there will

be a crackling + whistling sound during the discharge cycle (steam

and condensate passing through the orifice of the steam trap).

f. The steam trap should stay in the off position for a least 15 seconds

before cycling (less than 15 seconds if the steam trap is

undersized)

g. Discharge – ultrasound meter should increase the ultrasound level.

h. The steam trap has a fast on/off operation.

6.) Light Condensate Load Operation

a. Ultrasound levels will cycle on and

off at low ultrasound levels. This is an

indication of low condensate flows.

7.) Failure Modes

a. Leaking steam

Steam trap valve wear or linkage will cause the steam trap to

leak steam. The following are indicators of leaking steam:

• Ultrasound meter does not return to zero or baseline

after condensate discharge cycle.

• Ultrasound levels are continuous off base line and there

is not distinct cycle/no cycle operation.

b. Blowing steam

Steam trap valve or linkage

failure or over sizing (loss of

prime) will cause the steam

trap to blow steam directly

through the steam trap.

The following are indicators

of leaking steam:

• Ultrasound meter is at

full scale.

• Hearing a dominant

whistling sound and no

crackling.

STEAM AND CONDENSATE

SYSTEMS

STEAM SYSTEMS IN INDUSTRY

AND OTHER SECTORS

• Steam can be used for heating, drying, moistening and

sterilization of products in industry and other fields

• Steam has advantages in effective heat transfer, indirect or

direct heating and hygienic.

• Special attention shall be given in productivity of steam

production (exhaust gas and blowout losses), distribution

networks and steam users.

• Water treatment and high maintenance needs may increase

operating costs.

STEAM PRODUCTION

• Steam can be produced by steam boilers and steam generators.

• Key factors in economic steam production

o boiler plant

o continuous consumption monitoring

o skilled personnel

• Considerations in boilers

o boiler capacity meets steam requirements

o meters are in good condition

o out-blow is not excessive

o economizer is in operation

o heat transfer surfaces are clean

o boiler has no air leakages

o boiler insulation is in good condition

STEAM NETWORKS

• Steam use can be either direct or

indirect, but the used energy

amount is the same, but heat

losses may differ.

• In direct use the valuable

condensing water return shall be

checked regularly

• Superheated steam has lower heat

transfer coefficient than saturated

steam

• Moist steam stress equipment

more than dry steam

• Air mixed in steam reduces the

heat transfer coefficient

LEAKAGES

• Leaks in steam systems

o waste continuously energy (24/7)

o reduce network pressure and energy

flow

o waste valuable condense water

(treated water)

o reduce work safety (blasts)

• To be checked visually or with ultrasonic

detector

o safety valves, steam traps, orifice

connectors, gate valves, unattended

pipe-tunnels

o leakage inspections shall be made at

least twice per year

PIPE AND EQUIPMENT INSULATION

• Pipes, flanges, equipment and

valves shall be insulated

because of heat losses and

working safety

• Condense pipes always

insulated, except condense

valves

• Wet insulation causes energy

waste and outside corrosion

• Un-insulated DN 200 valve

may have up to 200 C

temperature and 5 kW

continuous heat loss

CONDENSE RETURN

• Condense return is important in indirect steam use. Condense

traps are important.

• Precise condense return causes:

o good utilization of condense heat content

o reduction in make-up water needs

• Closure of open condense tank causes

o reduction in heat loss

o reduction in tank corrosion

• Condense tank should be blanketed from oxygen entry by steam

etc

FAILURES IN CONDENSE TRAPS

• Condense return rate shall be monitored and maximized

• Fault trap causes steam-condense mix in condense pipe

leading to increased temperate and backpressure, increased

steam consumption, higher condense and high feed water

pumping costs

• Faults in condense traps should be seek by listening (man /

machine) and by temperature metering (every 2 to 4

months)

UTILIZATION OF BLOWOUT STEAM

• Benefits of blowout

o Reduced steam

consumption

o Lost blowout steam

reduces

o Capacity of condensing

network increases

• Utilization of blowout steam

o Blowout steam usage in

low pressure systems

o Preheating of combustion

air, compressed air and

rooms

o Heating of sub-cooled

condense or preheating of

process-water in condense

tank

ECONOMICAL USE OF STEAM

• Steam pressure

o Is defined by required temperature /pressure level

o It is important that temperature/pressure meets the

user requirements

o It is important that pressure fluctuation is as small

as possible

o Steam networks can be divided by pressure

reduction valves to different pressure subnets

EQUIPMENT CONSIDERATIONS

• Very important that process automation works properly

• Steam network and equipment shall be started slowly

• Steam heated equipment shall have thermal insulation

• Open liquid surfaces shall be covered against evaporation

• Bypass valves shall be kept closed and watertight

• Minimization of steam pressure, finally replacing steam with

hot water

• Drying first by mechanical water removal, then steam-drying

and avoid over-drying

• Avoid unnecessary stand by use of steam systems

Install air-atomizing and low-nitrogen-oxide (NOx) burners for oil-

fired boiler systems.

Install automatic boiler blow-down control.

Conduct flue gas Test of boilers.

Install an automatic flue damper to close the flue when it is not

firing.

Install tabulators to improve heat transfer efficiency in older fire tube

boilers.

Install low-excess air burners.

Install condensing economizers.

Install electric ignitions instead of pilot lights.

Install an automatic combustion control system to monitor the

combustion of exit gases and adjust the fuel-air ratio to reduce

excess combustion air.

Install isolation valves to isolate off-line boilers.

ENERGY CONSERVATION MEASURES FOR

BOILERS AND FIRED SYSTEMS

Maintain insulation on the heat distribution system. Replace

insulation after system repair, and repair damaged insulation.

Provide proper water treatment to reduce fouling.

Replace central plant with distributed satellite systems.

Downsize boilers with optimum burner size and forced draft

(FD) fans.

Operate boilers at their peak efficiency; shut down large

boilers during summer and use smaller boilers.

Install expansion tanks on hot-water systems that are properly

sized for the system.

Employ heat recovery through desuperheating.

Preheat combustion air, feed water, or fuel oil with reclaimed

waste heat from boiler blowdown and/or flue gases.

Install automatic controls to treat boiler makeup water.

Check steam trap sizes to verify they are adequately sized to

provide proper condensate removal.

Adjust boilers and air-conditioner controls so that boilers do not

fire and compressors do not start at the same time but satisfy

demand.

Clean boiler surfaces regularly to reduce scale and deposit,

which will improve heat transfer.

Replace noncondensing boilers with condensing boilers (15%–

20% higher efficiency when compared to new noncondensing

boilers).

Prevent dumping steam condensate to drain.

Survey and fix steam/hot-water/condensate leaks and failed

steam traps.

Convert steam system to low-temperature sliding temperature

hot-water system. Install complementing steam boilers where

needed.

Improve boiler insulation. It is possible to use new materials

that insulate better and have lower heat capacity.

Boiler Horse Power (HP):

BHP = (Lb/hr) * FE/34.5

Where Lb/hr is pounds of steam per hour and FE is the

factor of evaporation.

Cycle of Concentration of Boiler Water:

CYC = Bch / FCh

Where Bch is ppm water chlorides and FCh is ppm feed

water chloride.

Deferential Setting (lb):

Delta s = p1 – p2

Where p1 is the cutout pressure and p2 is the cut in

pressure.

FORMULAS

Factor of Evaporation:

FE = SH + LH / 970.3

Where SH is the sensible heat and LH is the latent heat.

Force (lb):

F = P/A

Where P is pressure (psi) and A is area (ln^2).

Horsepower (HP):

HP = (d * t) / (t * 33000)

Where d is distance, Fis force, and t is time.

Inches of Mercury (in):

lnHG = p / 0.491

Where p is pressure.

Percent of Blowdown:

%BD = (PP - RP) / PP

Where PR is popping pressure and RP is Reseat pressure

Rate of Combustion (Btu/hr

RC=H / (Vf * t)

Where H is heat released (BTU), Vf is volume of

furnace (ft^3), and t is time (hr).

Return condensate Percentage in feedwater

RC% = (MC - FC) / (MC – CC)

Where MC is the makeup conductivity (μohms).

Static Head pressure (lb)

SHP = Bpr * 2.31

Where Bpr = boiler preesure (psi)

Steam:

S = HP * 34.5 * t

Where HP is Boiler horsepower and t is time (h).

Temperature Conversions:

F to C

C = (F – 32) / 1.8

C to F

F = (1.8 * C) + 32

Total Force (lb):

TF = P * A

Where P is pressure (psi) and A is the area of valve

disc exposed to steam (sq.in.)

Water Column (ln):

WC = P / 0.03061

Where P is pressure (psi)