Phone : 918-271-1390 John@Americanfilter.com eptfe Membrane Filtration For The Chlor Alkali Industry
Brine Purification eptfe Membrane BackPulse Filters BackPulse Filters. 1 2 3 4 5 6 7 8 No Clarifier Required No Anthracite Filters Installed No Precoat Body-Feed System.. Zero Polymer Consumption Minimum Operator Attention Upgraded Brine Quality Brine Filters & Brine Softeners Sulfate & Chlorine Removal Cost reduction up to 2 M dollars Cost reduction up to 1.5 M dollars Reduced cost because of cellulose elimination for precoat & body feed No clarifier. no polymer consumption Fully automated systems Calcium / Magnesium ratio adjustment Single source responsibility Single source responsibility Cost savings not only due to reduced capital investment but also because of the elimination of polymers for flocculation in the clarifier and α Cellulose for precoat and body-feed required for polish filtration Minimum operator attention. Another advantage is the much smaller footprint of the Single Stage Back Pulse System Salt quality : Low Calcium to Magnesium ratio can be adjusted by brine quality upgrade procedure. Proven system with large number of eptfe membrane filter systems installed. Single source procurement for Brine Filters, Brine Softeners, Sulfate and Chlorine removal.
For additional information, contact us at the above address or call your local American Filter Systems representative. Pressure System. Conventional brine filtration with precoat filters is costly and requires a considerable amount of filter aid consumption as well as operator attention. To reduce the solids load to the precoat filters, large size clarifiers and sometimes anthracite filters are installed. The Candle Type, eptfe Membrane Filter System is one of the most economical systems for one pass brine filtration. Without the use of filter aids a sparkling clear brine is produced. Cost savings not only consist of the elimination of the use of cellulose for precoat and body feed, but clarifiers and media filters are eliminated as well. With eptfe membranes you can produce brine with an exceptionally low amount of suspended calcium and magnesium in one single separation step. Candle Type Backwash filters consists of a vertical, pressure type cylindrical filter shell with a conical bottom and a number of filter candles covered with membrane filter socks. The filter candles are mounted in a tube sheet clamped between the shell- and the top dome flanges. The single most important part of the filter is the eptfe membrane. The membrane is installed on a non metallic candle without the use of metallic clamps. For larger filter diameters an inlet header, mounted below the candles, provides optimum flow distribution and cake build up. Pictures : Top Middle Bottom Pressure Type Filters for Brine Filtration With eptfe Membranes. : Pressure Type Membrane Filter. : Support Member for Membrane. : Magnified picture of Membrane. In order to prevent lateral flow inside the needle felt backing material, the support members of the filter socks have thousands of small openings. The filtered brine flows directly into the perforated outlet tube and is collected in the filter dome. Optimum flow distribution during filtration and back pulse are essential for uniform cake build up and maximum cleaning efficiency. Cleaning the Filter. During filtration, suspended particles are separated from the brine and collected on the surface of the membranes. This causes pressure to increase across the filter. As soon as the maximum allowable differential pressure is reached, filtration is briefly interrupted to clean the membranes. A certain amount of filtrate is collected in the dome above the tube sheet. Low pressure compressed air is introduced at the top of the dome, driving the filtered brine into the candles in a reverse flow, slightly expanding the socks and removing the cake from the slick membrane surface. This backwash cycle takes a few seconds, and is followed by a sedimentation step for the cake to settle and collect in the conical bottom. Depending on the amount of solids separated from the brine stream, a concentrated sludge is evacuated from the filter after a pre- determined amount of backwashes. Key Benefits include: Eliminates Clarifiers, Anthracite Filters No precoat or body feed required Reduces waste disposal cost Simplified automation Maximum brine clarity. Minimum Operating- & Maintenance cost. Semi continuous Filtration Process
The Operation Of eptfe Membrane Backwash Filters Single Stage Brine Polishing. The Single Stage Brine Polishing system with GE Energy eptfe membranes is the most cost effective and economical system for brine polishing without the use of precoat or body feed. The back wash filter is equipped with GE Energy s eptfe membrane filter media and high flow candles for maximum membrane support, optimum filtrate drainage and equal flow distribution over the entire filter area, without relying on tangential flow inside the needle felt membrane support member. Filter cleaning. At the end of the filter cycle the filtrate valve is closed. A separate air connection provides the driving backwash force when a slowly opening vent valve is actuated. This causes the pressure within the shell to release gradually. The filtered liquid is forced in a reversed flow through into the candles, forming a thin layer of liquid between the cake and the membranes. The membranes expand slightly, and the accumulated solids are removed from the membrane surface. Expanded PTFE media for microfiltration on a needle felt support base has been successfully used in many applications. The uniform sub-micron pore distribution of the membrane provides instant clarity and an even cake build up. After the filter is filled, filtration starts without re-circulation, clarity is obtained without delay. During filtration, solids are accumulating on the Teflon membrane surface, building up a filter cake. As soon as the max. differential pressure is reached or a preset time has elapsed, the filter is cleaned. Complete and easy cake release at low back wash pressure and minimum back wash liquid consumption is achieved after each filter regeneration by using the slick physical properties of the eptfe membrane surface. To completely regenerate the membrane takes just a few minutes and is fully automated. Pressure Type Filter Shell. Compared to back pulse type cleaning, the membranes expand slowly, preventing the extra stresses in the membrane and protect the life span of the membranes. The entire back wash step takes approximately ten to fifteen seconds. Because of the large number of openings in the support core, the back wash liquid is not restricted in flow and is equally distributed over the entire candle area for optimum cleaning of the membrane surfaces. This eliminates channelling and incomplete cake removal which often occurs with other tubular elements. After a certain number of back wash cycles the filter cake collected in the conical bottom of the filter shell is removed as a slurry type cake. The number of back wash cycles is depending on the amount of solids suspended in the unfiltered brine.
. The Operation Of eptfe Membrane Backwash Filters Single Stage Brine Polishing. For economical sub micron separation of suspended solids from large brine streams, automatic back washfilters with eptfe membranes have proven to be very effective. With no moving parts, this type of filter requires a minimum of maintenance and operator attention. The back-wash filter consists of a number of special filter candles covered with eptfe membranes. These filter candles are mounted in a tube-sheet, clamped between the flanges of the top dome and the vertical filter tank. The filtered liquid flows inside the filter candle upward to the dome where it is leaving the filter. The suspended solids are collected on the membranes and are forming a filter cake. The lower part of the shell is a 60º conical shaped bottom. In this part of the filter, the solids are accumulated and evacuated from the filter after they are removed from the filter candles. For equal flow distribution and uniform cake build up, the unfiltered liquid enters the filter at the bottom part of the filter below the tube bundle via an optionally installed flow distribution header.
For additional information, contact us at the above address or call your local American Filter Systems representative. Vacuum- Backwash Filters for Brine Filtration With eptfe Membranes. Vacuum System. Filtration with eptfe membranes and candle type filters, is one of the most effective means of brine purification. With a pressurized system, the candles are placed in a coded pressure vessel and the brine is fed to the filter with an expensive corrosion resistant feed pump. The candles are mounted in a carbon steel, rubber lined tube-sheet. For membrane replacement, all the filter candles are removed from the filter shell at the same time. In addition to the traditional pressure system, AFS Inc. provides our customers with an alternative, less expensive, and easier system to operate a Vacuum brine filter system. This vacuum system uses the same filter candles and eptfe membrane technology as the pressure system, for superb brine clarity. Instead of using pressure to provide the driving force for filtration, a vacuum is used to create a differential pressure for adequate flow. The maximum differential pressure with a pressure system is approximately one bar. The same differential pressure can be generated with a well designed vacuum system. An AFS vacuum filter for brine purification consists of an inexpensive atmospheric filter tank (rectangular or cylindrical). The tank may be rubber lined or protected against corrosion by a glass flake lining. This vacuum system reduces the capital cost by minimizing the amount of piping, valves, instruments and automation. Substantial cost savings are created by eliminating expensive coded pressure vessels. Standard Filter Design Magnified picture of an eptfe Membrane. In the top part of the tank, several individual outlet headers with filter candles are mounted, providing sufficient filter area even for large brine flows. One standard filter tank contains up to 20 outlet headers for a maximum total filter area of about 145 m2. The footprint of such a filter tank is approximately 2.4 x 3.1 m. For very large flows, larger and additional filters can be installed. All the outlet headers are connected to a vacuum system. The filtered brine is pumped to the clear brine storage tanks. A vacuum tank is installed to remove possible vapors who may reduce the vacuum. Because there is no air passing the membranes, the installed vacuum pump can be small. For smaller filter systems, no extraction pumps for brine evacuation need to be installed. To clean the filter candles, the inlet valve is closed, the backwash (air) valve is opened and a small amount of filtered brine, collected in the outlet headers, is used to remove the filter cake from the membranes. The cake and the spent backwash liquid is collected in the filter vessel. There is sufficient volume provided in the filter tank to hold the entire amount of backwash liquid. After about 60 seconds settling time the cake can be removed as a slurry type of sediment from the conical bottom of the filter tank. The entire cleaning operation takes less than 90 seconds. That is why we call this Semi- continuous operation.
PID for a two filters in one tank system. 8 headers per filter. 160 candles for 58 m² filter area installed in each filter. With a well sized filtered brine storage tank and sufficient spare parts at hand, this system can be reliably operated with no back up / spare filter installed. The automation of this system is very simple. Per filter, there are only 3, or for larger flows, 4 automated valves installed. In addition to the above, some manual operated valves for the acid wash and vacuum system are required. For membrane replacement, the filtration process is briefly interrupted. The liquid level in the tank is reduced to just below the outlet headers. One outlet header with (maximum 20) candles can now be removed. The outlet header connection is plugged off or a spare outlet header can be mounted. This operation takes less than half an hour of filter down time. There are no special tools required. Vacuum only required for priming of system during start up. In the above configuration, (PID) we installed two separate filters ( A & B) in one single tank. Both filters can be operated independently from each other. One of the two filters can be in a chemical cleaning cycle, where the membranes are washed with acid, while the other filter remains on stream. This vacuum filter system has the same advantages than a typical pressure type eptfe membrane filter. Key Benefits include: Elimination of Clarifiers, Elimination of Anthracite Filters Maximum brine clarity. No precoat or body feed required Reduces waste disposal cost Simplified automation Minimum operator attention Reduced maintenance cost. Semi continuous operation Standard Systems Two filters - Single tank. Model Candles Area m² Size m DS- 75 DS-150 DS-235 DS-315 20 x 2 40 x 2 60 x 2 80 x 2 7 /14 15/30 22/44 29/58 Single tank filters. 1.5 x 0.9 1.5 x 1.5 1.5 x 1.8 2.4 x 1.5 Model Candles Area m² Size m BWV- 315 80 29 1.5 x 1.2 BWV- 625 160 58 2.4 x 1.2 BWV- 935 240 87 2.4 x 1.8 BWV-1245 320 116 2.4 x 2.4 BWV-1550 400 144 2.4 x 3.1 Above standard filters are rectangular open top tanks with a 60 degree conical bottom. Inside rubber lining or glass flake coating. Internals Polypropylene or CPVC. System components such as piping and valves made of CPVC or according to customer specifications. Platforms for accessibility of filter candles are made of coated carbon steel. Grating: galvanized. Standard automation with a PLC.
Filter Candle For eptfe Membrane Backwash Filters eptfe Membrane Filter Candles. In order to consistently produce solids free filtrate over an extensive period of time, it is important that a robust, high quality membrane is installed. Other important criteria for optimum filtration, cake build up and cleaning are that the filter candle has to provide sufficient support for the membrane as well as optimum filtrate drainage area. During filtration, the filter cake must be equally distributed over the entire length of the candle. The filtered liquid is passing the membrane and the backing material, in this case a needle felt. In order to prevent any lateral flow inside the felt, we install a heavy duty support / drain member with thousands of small openings. The filtered liquid flows without restriction via the inner drain tube into the filter dome (pressure), or outlet headers (vacuum). For optimum cake release and membrane cleaning, a certain amount of filtrate is collected in the dome or outlet headers. Low pressure compressed air is introduced, driving the filtered brine into the candles, in a reverse flow, slightly expanding the socks and removing the cake from the slick membrane surface. Because of the unrestricted flow, the backwash liquid is equally distributed and all the solids collected on the membrane surface are removed over the entire candle area. The candle elements contain NO metal parts (such as clamps), which eliminates traditional concerns about corrosive attack and damage to surrounding elements. We also offer a refurbishment program to re-sock the candle elements and to maintain the integrity of the system. Downtime associated with filter replacement can be reduced by 80% over other membrane systems. Filter candle For eptfe membrane Filtration. Inner drain tube Nut for assembly in tube sheet Tube sheet for pressure type filter Gasket Compression nut Gasket Sealing block Drain pipe end cap PTFE Membrane Support / drain member Support / drain member Advantages of this filter candle are : Simple and effective membrane installation No metallic clamps are used. Leak proof membrane installation. No membrane damage during installation Patent pending. Bottom end cap
Rebuilding Existing Filter Candles For eptfe Membrane Backwash Filters Single Stage Membrane Rebuilding Program Existing Filter Candles AFS Inc. developed a rebuilding program for existing CPVC filter candles installed with eptfe membranes. With certain type of filter candles, the membranes are attached with metallic clamps. In order to achieve the same advantages than what the GE non metallic candle provides, we can modify the existing candles by installing end caps with the GE clamping system NOT changing the original candle design with the exception of the bottom end cap where we need to add a threaded hole. Only in cases where the length of the candle is limited we need to make some minor additional changes. (see drawing) We install nipples in both existing end-caps and add the special designed CPVC adapters to both ends of the existing core. To provide additional drainage area, we as well drill holes in the circumference of the core or add a special drain member under the filter socks. This limits lateral flow inside the needle felt. The membrane is installed by gently sliding the sock over the perforated core assembly. Now the membrane is folded around the outer edge of the adapter blocks. Install the filter media gaskets into the sealing blocks and slide them onto both ends of the filter core assembly. Assembly is completed by installing the bottom end cap and the compression nut located at the top of the filter candle. In addition to the ease of assembly, this design provides optimum sealing capabilities. Because of the lack of sharp edged metallic clamps, membrane damage during assembly into the tube sheet is eliminated. Rebuilt Filter Candle For GE Energy eptfe membrane Filtration. Patent pending. Bottom support Stabilizes the candle in 3 directions. The candle elements contain NO metal parts which eliminates traditional concerns about corrosive attack and damage to surrounding elements during installation Advantages of this modification are : * Simple and effective membrane installation * No metallic clamps are used. * Easy and leak proof membrane installation. * No membrane damage during installation in filter. * Simple but effective bottom support.
Constant flow Laboratory Test Filter For eptfe Membrane Backwash Filters The significance of testing. It is very important that the basic design parameters for an eptfe membrane filter system are accurately determined. Almost all suspensions have different filtration characteristics. For instance with brine filtration we see many different kinds of salt from numerous sources. Also the make up water varies from plant to plant. The design parameters are : * Flow rate * Cycle length * Cleaning efficiency * Membrane micron particle retention To accurately determine these values we have two types of test filter available. A laboratory filter for initial testing and a 3 candle fully automated pilot test filter. Before installing the large size test unit at a customers plant, we prefer to run a number of laboratory tests in order to determine if eptfe membrane filtration is suitable for that certain application. We can perform these tests at the customers site or in our own laboratory. For each tests we need 2 gallons of brine or a representative salt sample of about 20 pounds. If the laboratory tests are successful, we always suggest to run the automated pilot-filter for an extended period of time. Process fluctuations may influence the test results and in most cases we can obtain reliable data within a 1 to 2 week period. This filter is installed with 3 full size filter candles for a total filter area of about 10 ft2. For a detailed description of the 3 candle test filter, see our special brochure. The laboratory filter, a very simple test unit in design and operation and consists of small pressure vessel fitted with an internal filtering area. A peristaltic pump feeds the filter at a constant flow. During a 20 minutes period and at 60 seconds intervals, we accurately measure the increasing pressure. From the obtained data, the filter area required to handle a specified volume of liquor in a given amount of time can be calculated. To determine the cleaning efficiency of the membrane we repeat the test several times, cleaning and reusing the same membrane. For each test we need about 4 liters of liquid. The filter area is 0.00181 m2. Required utilities : 110 V 60 Hz
Constant Pressure Test Filter For eptfe Membrane Backwash Filters The importance of testing. It is very important that the basic design parameters for an eptfe membrane filter system are accurate. Almost all suspensions have different filtration characteristics. For instance with brine filtration we see many different kinds of salt from numerous sources. Also the make up water varies from plant to plant. These parameters are : * Flow rate * Cycle length * Cleaning efficiency * Membrane micron particle retention To accurately determine these values we have two types of test filter available. A laboratory filter for initial testing and a 3 candle fully automated filter. Before installing the large size pilot unit at a customers plant, we prefer to run a number of laboratory tests in order to determine if eptfe membrane filtration is suitable for that certain application. We can perform these tests at the customers site or in our own laboratory. For these tests we need 10 gallons of brine or a representative salt sample of about 20 pounds. If the laboratory tests are successful, we always suggest to run the automated test-filter for an extended period of time. Process fluctuations may influence the test results and in most cases we can obtain reliable data within a 2 week period. For a detailed description of the 3 candle test filter, see our special brochure. Laboratory Test Filter The laboratory filter, an extremely simple test unit in design and operation, consists of small pressure vessel fitted with an internal filtering area. This filter is a very valuable tool for establishing the flow rate as well as the clarity and probable cycle length. During a 20 minutes period and 60 seconds intervals, we accurately measure the flow at a constant pressure of 15 psi or one bar. From the obtained data, the filter area required to handle a specified volume of liquor in a given amount of time can be calculated. We use a Log / Log graph where flow over time can be easily extrapolated. A non compressible cake will produce a straight line. To determine the cleaning efficiency of the membrane we repeat the test several times, cleaning and reusing the same membrane. For each test we need about 2 liters of liquid. The filter area is 0.001962 m2. Required utilities, 15 psi / 1 Bar air pressure.
Fully Automatic Test Filter For eptfe Membrane Backwash Filters Test Filter for eptfe Membrane Filtration. Every application requiring liquidsolids separation is different. Before recommending a specific solution, we spend considerable time understanding the customer s process. Water, salt, chemical addition, solids composition and concentration, process conditions, temperature, and residence time are all contributing factors to the success of the filtration and clarification program. Our experts will analyze the customer's brine polishing operation from start to finish, to ensure full systems integration and maximum filtration performance. In order to calculate the size and number of filters, we need to know the flow rate and cycle length of that specific brine. It is very difficult to accurately size a filter system just from chemical analysis of the salt, water and subsequent brine quality. Therefore we always conduct filtration tests, first in our laboratory and if possible also with our full size automated test filter, at the customers production site. For laboratory tests we need a representative salt sample of about 15-20 pounds or 7-10 Kg. With the data obtained from these tests, we can reliably determine the optimum flow rate, length of the filtration cycle and brine quality. Fully Automatic test filter. Design data: Technical Information. Shell : Stainless steel lined Lining : Glass flake fining Piping : CPVC Valves : CPVC Skid : Stainless steel Pressure : 75 psi / 5 bar Temperature : 190 F / 70 C Filter candles : Number of elements : 3 Filter area total : 11.7 ft2/ 1.1 m2 Material Elements : CPVC / PP Diameter : 2.75 / 70 mm Length : 72 /1830 mm Connections Inlet : 1 Outlet filtrate : 1 Cake drain : 3 Air inlet : 1/2 Vent : 2 Electrical Optional Instruments : : 110 V 60 HZ : 220 V 50 HZ Inlet pressure : 4-20 ma Outlet pressure : 4-20 ma Differential pressure : Calculated (PLC) Flow control : PLC controlled Automation : PLC make : Type : For remote communication a telephone modem has been installed.
Rebuilding Existing Pressure Leaf And Candle Filters Existing Filter Systems. Many Chlor Alkali plants have capital intensive precoat filters installed. In most cases, these filters are well maintained and in a good state of repair. These filter systems are probably amortized but it is to costly to replace the existing conventional equipment with an Single Stage Brine Polishing System and install new eptfe membrane filters. In many cases we can rebuild these (older) systems and install filter candles with eptfe membranes. One of the requirements is that the filter housing has a vertical shell and a conical bottom. To hold the filter candles, we can either install a tube sheet or individual outlet headers. Also the piping system has to be modified as well as the automatic control. A small number of additional valves have to be installed as well as some new instruments. We can modify the existing filters to a pressure or a vacuum type system. For a description of these systems see our detailed literature. In case multiple filters are installed, we can rebuild one filter at the time, eliminating downtime of the filter system and consequential loss of brine production. Rebuilding existing filters is a valuable option to improve your brine quality, particularly in cases where mercury or diaphragm cells are replaced with membrane type cells. Pressure Type Membrane Filter Key Benefits include : Eliminates Clarifiers, Anthracite Filters No precoat or body feed required Reduces waste disposal cost Simplified automation Maximum brine clarity. Minimum Operating- & Maintenance cost Magnified picture of a Membrane. The Single Stage Brine Polishing system with GE Energy eptfe membranes is the most cost effective and economical system for brine polishing without the use of pre-coat and body feed. The back wash filter is equipped with eptfe membrane filter media and high flow candles for maximum membrane support, optimum filtrate drainage and equal flow distribution over the entire filter area, without relying on tangential flow inside the needle felt membrane support member. Expanded PTFE media for microfiltration on a needle felt support base has been successfully used in many applications. The uniform sub-micron pore distribution of the membrane provides instant clarity and an even cake build up. Complete and easy cake release at low back wash pressure and minimum back wash liquid consumption is achieved after each filter regeneration, by using the slick physical properties of the eptfe membrane surface. At the end of the filter cycle the filtrate valve is closed. A separate air connection provides the driving backwash force. Filtered liquid, collected in the dome or outlet headers, is forced in a reversed flow through into the candles, forming a thin layer of liquid between the cake and the membranes. The membranes expand slightly, and the accumulated solids are removed from the membrane surface. To completely regenerate the membrane takes just a few minutes and is fully automated.
www.aatechwater.com For additional information, contact AFS Inc. or AATech water at the above address Conventional Brine Treatment and Brine Treatment for eptfe Membrane Filters Single Pace - Membrane CONVENTIONAL BRINE TREATMENT BRINE TREATMENT FOR eptfe MEMBRANE FILTERS
Comparing eptfe Membrane Filtration with Conventional Precoat Filters. PRECOAT / BODY_FEED FILTRATION. In order to reduce the consumption of precoat and body-feed with precoat filtration, long filter cycles are required. Downtime for filter cleaning can take more than one hour. α Cellulose is expensive and storage plus handing requires a lot of operator time. Long filter cycles can be obtained by reducing the amount of solids to a level as low as possible. This requires the installation of clarifiers and anthracite filters. Clarifiers have a large footprint and anthracite filters produce a large quantity of backwash liquid. Cost of α cellulose for pre-coat and body-feed is high. Costly mixing and dosing systems for pre-coat and body-feed consisting of tanks, agitators, piping and valves are installed. Operator attention and maintenance cost of clarifiers, anthracite filters, precoat filters and precoat systems are high. Cleaning of the filter, precoat plus body-feed make up and precoating takes more than one hour. To accelerate sedimentation in the clarifier and increase efficiency of anthracite filters, in many cases flocculants and or coagulants are required. The amount of chemical waste and the cost of disposal is doubled because of the addition of α cellulose filter aid. SINGLE STAGE eptfe MEMBRANE FILTRATION. With Single Stage eptfe filtration total downtime for filter cleaning is less than two minutes. Filter cycles can be as long as several hours or as short as 30 minutes. Short filter cycles do not influence the over- all performance of One Pass Filtration. eptfe membrane filters can handle brine with a high as well as a low solids content. Pre separation with clarifiers or anthracite filters is NOT required, greatly reducing the cost for the installation of capital equipment. We do not use α cellulose with Single Stage eptfe membrane filtration. It eliminates the cost for the consumption and disposal of this material. NO capital investment for mixing tanks, pumps, piping, valves and instruments. No operator time required for pre-coat and body-feed make up. Single Stage Brine filters are operating fully automatically and require very little operator attention. Cost for consumables as flocculants and coagulants are eliminated. We use just a small amount of backwash liquid with Single Stage membrane filtration. The amount of chemical waste is reduced to a minimum and the required backwash liquid for anthracite filters is eliminated. Single Stage eptfe membrane filtration and Pre-coat / body-feed filtration are very different. With Pre-coat / body-feed filtration solids such as calcium and magnesium are fully imbedded in α cellulose and this type of filtration can be compared to depth filtration. Single Stage eptfe membrane filtration is strictly surface filtration. All solids are collected on the surface of the Teflon membrane. Because we do not use a filter aid to enhance the performance of the filter, we fully rely on the quality of the brine. With One Pass filtration, the operator attention has shifted from filtration to brine treatment.. In order to produce an optimum filterable brine, treatment becomes very important. Factors as Calcium / Magnesium ratio, chemical excess, residence time, temperature, agitation are determining the filtration characteristics and as a result, the efficiency of the filter system. Other factors such as, the quality of make up water as well as the presence of organic matter do influence the performance of the filter. To properly design a filter system it almost always requires testing and a careful study of the brine treatment process and brine quality With existing systems where clarifiers are installed, the solids in the feed to the filters are mostly magnesium and very fine. For these applications we actually are adding some solids from the underflow of the clarifier to the raw brine filter feed. These extra solids are allowing to form a more filterable cake and extend the filter cycle.
Filtration Characteristics of Brine eptfe Membrane Filtration with IMPOSSIBLE? eptfe membrane filtration even for brine made from a low Ca / Mg ratio salt? AFS Inc. developed a technology where almost ANY type of salt is suitable for eptfe membrane filtration even without the use of a clarifier or any other pre clarification. Brine with a low Calcium to Magnesium ratio is difficult to filter. Also other contaminants such as Natural Organic Matter can influence the filtration characteristics of treated brine in a negative way. Now, change in salt quality is not a problem anymore. With the AFS Inc. Brine treatment process, the filtration characteristics of the brine to be filtered are monitored and automatically corrected, upgraded by influencing the Calcium to Magnesium ratio. An automatic control system calculates the increase of differential pressure over time. Also the brine flow is automatically corrected for. If the increase of differential pressure is higher than projected, the calcium to magnesium ratio is increased by adding a small amount of Calcium Carbonate. What are the advantages? A low quality, low cost type of salt can be used. Change in salt quality is no longer a problem. A high purity, low solids content brine is produced. No expensive clarifier or other pre- separation step required. No Cellulose pre-coat or body feed necessary.
For additional information, contact us at the above address or call your local American Filter Systems representative. eptfe Membrane Backwash Filters For Sodium Hypochlorite And Sodium Chlorate To produce high quality sodium hypochlorite and sodium chlorate it is critical to remove all suspended solids. Sodium hypochlorite is an unstable product and decomposition of the product may be influenced by initial concentration, ph, contaminants, such as metals, and suspended solids (calcium and magnesium). Also, before crystallization of sodium chlorate, suspended iron compounds should be reduced to aminimum. Conventional filtration, using pre-coat filter technology requires a considerable amount of filter aid and operator attention to meet these challenging requirements Candle type filters, that utilize eptfe membrane technology, is one of the most economical systems to obtain a sparkling clear filtrate without the use of any filter aids. Candle type backwash filters consist of a pressurized vessel with a cylindrical filter shell and a conical bottom. Inside this vertically constructed vessel are a number of filter candles covered with eptfe membrane filter socks. The filter candles are mounted in a tube sheet clamped between the shell- and the top dome flanges, or in some cases arranged with outlet headers in place of the tube sheet. In case of a vacuum operated system, a rectangular atmospheric filter tank is provided. The filter candles are installed in individual outlet headers. The single most important part of the filter are the eptfe membrane socks, as they do all the functional work of removing the solids from the liquid without blinding the supporting felt. This is ue to the sub-micron structure of the eptfe membrane that allows for true surface filtration to occur, as opposed to depth filtration of the older pre-coat technology where the solids are embedded in filteraid. Each membrane sock is installed on a support candle without the use of metallic clamps, and all wetted parts are made of non-metallic materials. Pressure type eptfe membrane filter. Vacuum type eptfe membrane filter. Magnified picture of an eptfe Membrane. With eptfe membranes you can produce a filtrate with an exceptionally low solids content in one single separation step. In order to prevent lateral flow inside the needle felt backing material, the candle support cores of the filter socks have a large number of small openings. The filtered brine flows directly through these cores into the perforated outlet tubes and is collected in the filter dome. Optimum flow distribution during filtration and back pulse are a necessary for uniform cake build up and maximum cleaning efficiency. During filtration, suspended particles are separated from the brine and collected on the surface of the membrane socks. This causes the pressure across the filter to increase. As soon as the maximum allowable differential pressure is reached, filtration is briefly interrupted to clean the membranes. A pre-determined amount of filtrate is collected in the dome or the outlet headers. Lowpressure compressed air is used to reverse the flow of filtered brine, driving it back through the candles. The socks expand slightly and release the cake from the slick membrane surface. This backwash cycle only takes a few seconds and is followed by a sedimentation step whereby the cake is allowed to settle and collect in the conical bottom. A concentrated sludge is evacuated from the filter after a predetermined amount of backwashes. Key Benefits include: No precoat or body feed required. Reduces waste disposal cost. Simplified automation Maximum product clarity. Minimum Operating & Maintenance cost (labor and material) AFS is introducing affordable, Semi-continuous filtration with eptfe membranes.
Process Data - Questionnaire Brine Filtration Type of Brine NaCl KCl Type of salt Rock salt mined & dissolved Rock salt from wells, solution mining Solar salt Vacuum pan salt Process waste Supplier : Origin : Chemical composition salt : Chemical composition Water source Water analysis Well water Surface water (Filtered) City utility Demineralized water or condensate : Chemical composition Brine Ph : Free Chlorine : ppm Number of chemical treatment tanks 1 2 3 Amount of chemicals added Na2CO3 ppm NaOH ppm Chemical excess Na2CO3 ppm NaOH ppm Residence time / temperature Tank 1 Minutes C Tank 2 Minutes C Tank 3 Minutes C Clarifier installed Yes No Chemicals added flocculants Yes No Type and Quantity Present flow gpm m3/hr
Operational Data - Questionnaire Brine Filtration Operating temperature F C Design temperature F C Operating pressure psi Bar Design pressure psi Bar Required Actual Brine Flow gpm m³/hr Required Design Brine Flow gpm m³/hr Expected solids in feed brine: Chemical composition and quantity Presently installed filters Precoat Anthracite Membrane Present flow rate Gpm/ft² m³/m²/hr Present brine quality filtrate : Chemical composition Required brine quality filtrate : Chemical composition Minimum number of filters : (Future system) Maximum number of filters : (Future system) To prevent the accumulation of sulfate in some cases, BaCl2 or BaCo3 is added. Please specify if BaSo4 is present in the brine stream. In some cases additional chemicals are added upstream of the filters such as corrosion inhibitors or chemicals to reduce the solubility of sulfates. Please specify if applicable. If you have any questions please contact this office. American Filter Systems Inc. John@Americanfilter.com