Post on 15-Jul-2015
transcript
Dec’ 2014
Overview of Filter Press | Nitesh Dattaram Kamerkar
ENERGY
ALTERNATIVE
INDIA , CHENNAI FILTER PRESS
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 1
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
NEED FOR FILTER PRESSES
Filter presses are sometimes called "Plate-and-Frame Filters" which describes the
style of filters developed from the 1800's onwards. The majority of today's filters are
more correctly called "Membrane Plate Filters".
Many processes in the food, chemical or pharmaceutical industries make products that
are liquid-solid suspensions or slurries. These mixtures are a little like a runny mud or
Milk-shake. The solids in them do not dissolve in the liquid but are carried along in it.
Filter presses separate the solids from the liquids so that the useful part can be
processed or packaged.
Filter presses generally work in a "batch" manner. They are loaded with slurry before
completing a filtering cycle and producing a batch of solid filtered material, called the
filter "cake". The solid is removed, the press re-loaded with slurry and the batch cycle
repeated.
A filter press uses increased pressure to maximise the rate of filtration and produce a
final solid with a low water content. This is more efficient than filtration using a funnel
and paper which utilises the low pressure caused by the weight of liquid above the filter
paper.
WORKING PRINCIPLE OF FILTER PRESS
Filter press is simply a kind of machine, which performs Filtration & separation during its Press
operation.
A filter press consists of a series of chambers containing square or rectangular filter
plates supported in a frame. Once the filter chambers are loaded with slurry, the plates
are forced together with hydraulic rams that generate pressures typically in the region of
100 pounds per square inch (70,000kg per m2). For comparison, a car tyre would be
inflated to around 30 pounds per square inch.
Each plate is covered by a material or membrane that acts as the initial filter when the
press is in operation. As the solid filter cake builds up, the cake adds to the removal of
fine particles. The solution coming through the filter, called the filtrate, will be very pure.
If it is not wanted the filtrate can be drained away for safe disposal.
At the end of the compression, the solid filter cake can be removed. The whole process
Filter presses are extensively used in Food industry, because there are lots of things that
would not be very pleasant to eat if they were “lumpy”. For example vinegar, honey,
water, fruit juice, soft drinks, edible oil.
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 2
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
is often computer controlled to make it automatic or semi-automatic.
**SOURCE: - http://www.putschusa.com
TYPICAL PROCESS SCHEMATICS
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 3
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
STEPS INVOLVED IN FILTER PRESS PROCESSES ARE AS FOLLOWED:-
CLOSING OF THE PRESS
As the filter is completely empty, the moving head is activated by the jacks that clamps
the plates. The closing pressure is self-regulated through the filtration.
FILLING
During this short phase, the chamber is filled with the sludge or slurry to be filtered. The
filling time depends on the flow of the feed pump. For sludge of good filterability, it is best
to fill the filter quickly to avoid caking in the first chamber before the last ones are filled.
FILTRATION
Once the chambers are filled, further input of sludge increases the pressure from the
increasingly thicker layer of filtered sludge on the cloths. The filtration can then be
stopped manually, by a timer, or, more conveniently by a filtrate flow indicator
automatically when no more filtrate is passing through.
FILTER OPENING
The moving head is drawn back to disengage the first filtration chamber. The cake is
released by its own weight. A mechanized system pulls out the plates one by one, the
speed of which can be adjusted for the cake texture.
WASHING
Washing the cloth should be done every 15-30 runs. For mid or large units, this can be
done on the press itself using high pressure water sprays (80-100 bar). However, the
washing requirements will depend on the type of sludge.
SLUDGE OR SLURRY CONDITIONING
If unconditioned sludge is filtered through plate assembly, the filter cloth gets plugged.
Notwithstanding this, the fine particles can pass through and reduce solids recovery
efficiency. To reduce the medium blinding and to improve the filter cake structure
during filtration, the sludge is conditioned with suitable agents like polymer to neutralize
and flocculate the solids. The conditioning produces a rigid sludge with a porosity that
allows for effective water drainage.
** It is not always required or involved in Filtration process. It depends on type of Liquid-
Solid mixture. It is widely employed in Water Treatment Process.
. . . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 4
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
CLASSIFICATIONS OF FILTER PRESS
PLATE & FRAME FILTER PRESS
Plate and frame filter press is the most fundamental design among all the other filter
presses, and majority nowadays refer it as “membrane filter plate”.
AUTOMATIC FILTER PRESS
It consists of larger plates and frames filter presses with mechanical “plate shifter”. The
function of the plate shifter is to move the plates and allow rapid discharge of the filter
cakes accumulated in between the plates. It also contains diaphragm compressor in the
filter plates which aids in optimizing the operating condition by further drying the filter
cakes.
RECESSED PLATE FILTER PRESS
Recessed plates are made up of polypropylene squares with concave depression and a
hole in the center. Two plates join together to form a chamber to pressurize the slurry and
squeeze the filtrate out through the filter cloth lining in the chamber. However there are
disadvantages to this method such as longer cloth changing time, unable to
accommodate filter papers as well as the possibility of forming uneven cake.
FILTER PRESS
PLATE & FRAME FILTER PRESS
OR
MEMBRANE FILTER PLATE PRESS
AUTOMATIC FILTER PRESS
RECESSED PLATE FILTER PRESS
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 5
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
SIGNIFICANT INDUSTRIES IN WHICH FILTER PRESSES ARE USED
EXTENSIVELY
PIGMENTS & DYE MANUFACTURING
Corrosive environment, elevated temperatures and often volatile atmospheres demand
suitable Filtration and Separation method. Over last few decades, Conventional devices
such as drum Filters & Centrifuges have been successfully replaced by Filter Presses.
Typical Applications are:-
Titan Dioxide (TIO2) {finishing/ desalting & waste/ neutralization }
Caustic Solutions
Acids
Coatings
FOOD & AGRICULTURE
Filter Presses are the standard for applications in the sugar industry as a Juice Purification
Systems. The robust and high performance design as well as the high degree of
automation makes these filters the ideal choice for many applications in this market.
Typical Applications are:-
Wine and Juices
Beer
Edible oils
“Green Energies” (Bio- ethanol)
Animal waste
Sugar & sweeteners processes
CHEMICAL / PETROCHEMICAL
The presence of contaminants in the petrochemical manufacturing process can have a
direct impact on the quality of the material produced. Therefore, Chemical/
Petrochemical Industries require large capacities filter presses with fully automatic
operation.
Typical Applications are:-
Calcium Carbonate (CaCO3)
Barium sulphate (Completion fluid)
Silicates (product & waste)
Polymers (Fibers)
Brine Solutions (Coolant recovery)
. . . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 6
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
RECYCLING & ENVIRONMENT
A major environmental problem, issues arises due to hazardous waste released by
numerous industries all across the world. Due to current strict Global environmental
Policies, filter presses are also contributing significantly in this segment.
Typical Applications are:-
Stone processing (cutting, polishing & gravel washing applications)
Plastic fibers (Carpet recycling)
Power plants (Flue Gas Desulphurization, FGD)
Industrial waste
Chemical waste
PHARMACEUTICAL & BIOTECH
Demand for precisely controlled processes and clean environments in Pharmaceutical &
Biotech industries can be met with Filter Press Systems.
Typical Applications are:-
Yeast
Bio solids
Seaweed
Blood plasma
Enzymes
PULP & PAPER
Although centrifuges are the preferred choice of dewatering equipment in this industry,
Filter Press Systems have proven to provide superior results in regard to solid capture rate,
final moisture content and salt removal (cake washing).
Typical Applications are:-
Green liquor (Soda Recovery)
Coatings waste treatment
MINING & MINERALS
Large capacity Filter Presses for harsh environments with their innovative cake discharge
system is an economic choice for this industry. There is a huge demand for large
capacity filter presses.
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 7
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
Typical Applications are:-
Mineral concentrates
Flotation slurries
Coal
Clays (Kaolin, Bentonite, Ceramics)
RECENT INNOVATIONS IN FILTER PRESSES
Filter Presses for Sludge Treatment 1
Filter press performance depends on type of Sludge which is going to be filtered. To
obtain higher efficiency & better performance in Filter Presses to treat all kind of
Sludge some conditioning agents are added on filter paper or filter cloth. So, there is
a lot of research & development going on around the globe for developing best
suited & economical Conditioning Agent or Flocculants. Diatomaceous Earth (DE), Fly
Ash are most commonly used Bulking Agents and Ferric Chloride, Alum, Lime,
Polyelectrolyte(polymer) are most commonly used Conditioning Agents.
Types of Sludge are:-
Hydrophilic organic sludge: Inorganic conditioning is often recommended to
enable satisfactory cake release due to minimal adherence to filter cloth.
Hydrophilic inorganic sludge: The filter press generally requires the addition of
lime only.
Hydrophobic inorganic sludge: It is very dense and ideal for the filter press. It is
dewatered without any preliminary conditioning.
Oily sludge: The filter press can be used to treat sludge containing light oils, the
presence of grease can sometimes impair the smooth running of the filter; clothes
have to be degreased at frequent intervals.
The filter cloths are woven fabrics using monofilament or multifilament synthetic fibers
or a combination of both. The most commonly used materials are polypropylene,
polyester, and nylon.
1 http://www.lenntech.com/library/sludge/presses/filter-press.htm
. . . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 8
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
Candle Filter Technology 2
Candle Filters are installed for clarification and recovery applications from liquids with
low solids content from 5% to less than 1% solids and even down to trace amounts.
AUTOMATIC PROCESS CYCLE:-
Filling: The slurry feed enters the bottom of the filter vessel.
Filtration: The slurry is pumped under pressure into the vessel. Cake will deposit on the
outside of the candle; the separated filtrate will flow through the filtrate pipe and
the registers. This process continues to a maximum pressure drop, the maximum cake
thickness, or the minimum flow.
Washing: Displacement washing or recirculation washing.
Drying: Blowing gas, steam or “shock” drying.
Heel Filtration: The liquid remaining in the vessel cone after filtration or washing is
completely filtered.
Cake Discharge: Gas flows through the register pipes, and down the filtrate pipe. The
filter media gently expands allowing for cake discharge. Alternatively, the cake can
be discharged as a slurry.
Sock Cleaning after Cake Discharge: If necessary, sock cleaning is accomplished by
filling and circulating cleaning fluids while blowing gas in the reverse direction to the
filtration direction, which creates a turbulent mixture or a quasi-ultrasonic
cleaning effect.
2 http://www.bhs-filtration.com/products/candle_filter.aspx
Candle Filter
. . . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 9
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
Candle Filter Technology is Modular in nature that means we can implement this
technology in small Bottle-size vessel. In which an upside-down candle, screwed inside
that Bottle-size vessel.
Energy efficient Membrane Filter Press 3
From energy use and technology gap audit studies in various chemical industries in
Ahmedabad chemical cluster, below mentioned things are identified:
Energy efficiency improvement opportunities
Environment and safety improvement of workers
Design flaws in the conventional filter press
Operational & maintenance practices in conventional filter press
The drying cost is one of the major costs in the overall production process of chemicals, in
typical chemical industry. Apart from the energy cost, drying time is one of the major
time consuming area in overall production process of chemicals, in typical chemical
industry the drying time would be around 72 hours per batch. The existing installed
conventional dryer takes 72 hours for processing one batch. If combined with a
membrane filter press the drying time is reduced to 49 hours per batch. This not only
saves energy consumed by the dryer, through reduced hot air consumption for hot air
generator but also enhances the productivity of the dryer as the drying process
becomes faster process.
3 www.bee-india.nic.in – Detailed Project Report (DPR) on Membrane Filter Press, DPR No. AMD/CHM/MFP/07
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 10
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
Advantages of replacing the conventional filter press with Energy Efficient membrane
filter press are:
Reduction in load on HAG and hence wood consumption
Improved productivity
Improved working environment
Faster filter press process, it leads to energy savings
Improves the efficiency of the unit
Reduction of deforestation and GHGs emissions
COMPARISON BETWEEN CONVENTIONAL & MEMBRANE FILTER PRESS
Sr. No. Details Conventional Filter Press Energy Efficient Membrane Filter Press
1 Drying time in Dryer due to caking More Less
2 Load on Hot Air Generator (HAG) More
Less
3 Environment pollution High (partial combustion & more fuel consumption)
Low ( Complete combustion & less fuel consumption)
4 Caking Time High Low
5 Operational Cost ( due to compressed air usage)
High Low
6 Heat Losses High Low
From the above table it is clear that Energy efficient membrane filter press has significant
advantages in Energy, Environmental, Economic & safety aspects over the conventional filter
press. It is therefore, justifiable to install energy efficient membrane filter press in place of
conventional filter press.
. . . . . . . . . . . . . . . . . . . . . . . . . . P a g e | 11
FILTER PRESS
ENERGY ALTERNATIVES INDIA (EAI), CHENNAI
Detailed Technology Assessment Report (from Detailed Energy Audit Report on Membrane
Filter Press done by BEE at Chemical SME Cluster, Ahmedabad, Gujarat, India.)
Sr. No.
Parameter Units Value
1 Drying time in conventional filter press hrs/batch 72.00
2 Drying time in new membrane filter press hrs/batch 49.00
3 Volume processed per batch litre 1280.00
4 Wood consumption in HAG (Hot Air Generator)
Kg/hr 70.00
5 Wood consumption in HAG with conventional filter press
Kg/batch 5040.00
6 Wood consumption in HAG with membrane filter press
Kg/batch 3430.00
7 Specific fuel consumption for conventional filter press (@ 1280 Litre/batch )
Kg/litre 3.94
8 Specific fuel consumption for membrane filter press (@ 1280 Litre/batch )
Kg/litre 2.68
9 Savings in specific fuel consumption Kg/litre 1.26
10 Annual operating batches Nos. 150.00
11 Annual production capacity @ 1280 Litre/Batch
Litre/annum 192000.00
12 Wood energy saved per annum tonnes/annum 241.50
13 Average fuel cost /tonne 3000.00
14 Total monetary saving ( in Lakh) 7.26
15 Total investment required ( in Lakh) 24.20
16 Simple payback period Years 3.33