BHS-Filtration specializes in thin cake-filtration, cake washing and drying technologies. BHS understands that no single filtration system can solve every problem. BHS technicians are trained to objectively analyze filtration data and to propose reasoned solutions for your problem or project.

Their Products include Rotary Pressure Filters, Autopress, Vacuum Belt Filters, Pressure Plate Filters and Candle Filters.

Technical Articles

Thin-Cake Filtration Theory

In most industrial solid-liquid separation applications, the process steps of filtration, washing and
dewatering (drying) are conducted on one filter. This paper describes the thin-cake filtration
theory for these operations.

• A Treatise of Filter Cake Washing Mechanisms In Pressure and Vacuum Filtration Systems

During many chemical and pharmaceutical process operations, cake washing is required for the removal of the mother liquor, exchange of solvents, dissolution of soluble components and the displacement of insoluble contaminants. This article introduces pragmatism into cake washing theory and will help to guide engineers during their decision-making processes.

• Clarification of API Slurries and Recovery of Solids

Abstract: Candle Filters and Pressure Plate Filters are installed for clarification and recovery applications from liquids with low solids content. The candle filters are vertical candles while the pressure plate filters are horizontal plates and both are designed for complete containment and automatic cake discharge. The cake structure as well as the process parameters determines the optimum thin-cake technology.

• "Reprint from "Pharmaceutical Engineering" , Jan/Feb 2007, The Official Magazine of the ISPE, International Society of Pharmaceutical Engineers.

This article discusses how the use of thincake vertical candle filters and horizontal pressure plate filters can efficiently remove activated carbon, metal catalysts, and trace insolubles from Active Pharmaceutical Ingredient (API) slurries.

• Thin-Cake Filtration Technologies for Removing Activated Carbon, Catalysts and Other Trace Solids From Active Pharmaceutical Ingredient (API) Slurries

Abstract: The BHS technologies of Vertical Candle Filters and Horizontal Pressure Plate Filters provide improved product quality with more efficient operations compared with manual pressure filters. The different technologies allow for the selection of the optimum process solution depending upon the cake characteristics and cake structure. Fully automatic operations provide for complete containment of the solids and liquids for reduced maintenance costs and overall project savings.

• A Six Sigma Approach to Evaluating Vacuum Filtration Technologies

Abstract: This article compares three designs of vacuum belt filters (moving tray, rubber carrier belt and the BHS continuous-indexing technology). The evaluation had several stages from initial investigation, bench-top testing and finally pilot-scale testing. The BHS Continuous-Indexing Vacuum belt filter was the selected technology to replace a manually-operated filter press. The return-on-investment (ROI) calculation based upon the BHS process, operating and maintenance benefits allowed the project to be funded with a payback of less than 6 months.

• Clean-in-Place Operations for Thin-Cake Filtration Technologies

Abstract: This article discusses the choice of thin-cake (2-25 mm) separation technologies and their benefits to optimizing the effectiveness of the production process. The paper continues with a discussion of clean-in-place operations to meet current Good Manufacturing Practices (cGMP) guidelines including riboflavin test and validations. ANSI/ISA S88 (and IEC 61512-1 in the international arena) batch process control system standards are also examined. Finally, factory and site acceptance testing is described.

• Continuous-Indexing Vacuum Filter as Replacement for Filter Presses

Abstract: The BHS Continuous-Indexing Vacuum belt filter (CI-VBF) with 12 m2 of filter area replaced a 440 m2 filter press. The CI-VBF provided improved washing efficiency for a higher quality product, and lower operating and lower maintenance costs with a fully automated operation.

• BHS Pharma Rotary Pressure Filter Article

Abstract: The BHS Ph-RPF technology provides improved product quality with more efficient washing ratios compared with the inverting-basket centrifuges. Savings in solvent usage, energy consumption, maintenance costs and capital and installation costs result in overall project savings on the order of 4-6 to 1.

• Test it Right for Thin-Cake Filtration Operations

Abstract: The appropriate BHS testing procedures can help direct the selection of pressure or vacuum filtration equipment and ensure optimum equipment operation.

• Improving Process Operations with a Rotary Pressure Filter

Abstract: A rotary pressure filter can increase filtration rates, washing and drying efficiencies and eliminate organic solvent emissions.

• Evaluating thin-cake pressure filtration using the BHS Autopress technology

En español, Evaluación proceso de filtración por presión de tortas delgadas utilizando la tecnología Autopress de BHS.

Abstract: Thin-cake pressure filtration technology offers an alternative to agitated nutsche filters and centrifuges for solid-liquid separation, cake washing, and drying.

Solid-liquid separation and cake washing are integral steps in the production of bulk or final pharmaceutical products. Each step must be optimized, along with the downstream dryer.

Complicating this process is the number of competing technologies and options that can be employed to accomplish these steps. For example, most pharmaceutical processes will use either an agitated nutsche filter or a centrifuge for the separation and washing step.

This article discusses the use of the thin-cake Autopress pressure filter as an alternative to agitated nutsche filters and centrifuges. The results are applicable to specialty chemical and other applications with similar process crystals and requirements.

• Comparison of Gypsum Dewatering Technologies at Flue Gas Desulfurization Plants

Abstract: Recovering gypsum from flue gas desulfurization (FGD) plants is becoming more important as the technical feasibility of substituting FGD gypsum for natural gypsum in traditional applications such as wall board, cement and soil conditioners has been demonstrated. It is estimated that there are over 200 new coal-fired plants and over 1000 upgrades of existing coal-fired plants in various stages around the world. An important aspect of gypsum recovery is the solid-liquid separation technology that is used.

This paper discusses three technologies that are used by coal-fired power plants to dewater and dry gypsum. These are centrifuges, continuous vacuum belt filters (CBF) and continuous-indexing vacuum belt filters (CI-BF) and rotary vacuum filters. Each technology is examined for their ability to filter, wash and dry the gypsum to meet the moisture content for salable FGD gypsum as compared with natural gypsum. The paper continues with an analysis of the utilities required for each technology including electricity and water usage and the ability to reuse water in the process. Finally, maintenance, reliability, uptime and redundancy requirements are discussed as well as general overview of instrumentation and PLC controls and communication is covered.

The paper concludes by describing the important information that power plant engineers should review before deciding on a solid-liquid separation technology. These parameters include type of FGD process, type of coal, limestone purity, water analysis, operating data, composition of the gypsum slurry and other upstream or downstream equipment. Finally, to meet the plants overall environmental objectives, a unique approach is described that takes the wastewater treatment sludge and incorporates it with the gypsum for a cement product.

Industrial Water Filters

Res-Kem Industrial Water Filters filter or clarify water by removing sediment, turbidity, iron, unpleasant tastes, odors, suspended particles, or unwanted color commonly found in surface water.

The picture at right is a small multi-media filter used in an industrial setting.

Res-Kem industrial water filters can be used in a variety of service conditions including municipal, institutional and industrial water filtration applications. With the utilization of the correct pressure tanks, valves and accurate filter media choice Res-Kem's industrial water filters can suit most industrial water filtration requirements. Our industrial water filter equipment can be designed to operate manually, semi- or fully-automatically and require very limited technical knowledge. Res-Kem Industrial Water Filters can utilize several different types of filter beds.

• Sand:

Commonly used in most standard industrial water filtration systems for removal of suspended solids and turbidity.

Anthracite:

Performs nearly identical to a sand bed and used in industrial water filtration equipment where silica pick-up from sand is objectionable.

In-Depth:

These beds are composed of several layers of different media size. In-depth filters allow higher loading rates and longer runs. A sand and anthracite bed is a typical industrial configuration. In-Depth filters will remove sediment down to the 20-30 micron range.

Multi-Media:

Consists of multiple layers of sand, anthracite and garnet. Multi-Media industrial water filters remove sediment down to the 10 micron range.

Activated Carbon:

This water filtration equipment is recommended for the removal of unpleasant tastes and odors, dechlorination, or organic contaminant adsorption. Depending upon the exact application a variety of carbon types can be used.

Quality Tank Construction

All standard Res-Kem industrial water filters include pressure tanks constructed of high quality welded steel designed for 100 psi working pressure and tested for 150 psi. Standard pressure tanks are equipped with inlet and outlet connections, top mounted loading port (either handhole or manhole), and a side filter media removal fitting. Due to the corrosive nature of certain filter media types, all tanks are epoxy lined. Stainless steel or Fiberglass pressure tanks are available for custom industrial water filters.

Underdrains

The Res-Kem hub and lateral distribution system is designed to utilize the entire bed area during all flow rates. This minimizes channeling during periods of low flow. The entire industrial water filter system is constructed of PVC with schedule 80 laterals ensuring maximum corrosion protection and strength.

Diaphragm Valves

To answer a need for truly trouble-free, labor saving, automated equipment; Res-Kem engineers designed the ultimate industrial water filter using a "Nest" of diaphragm valves. The angular design, high lift, and large seat opening of these hydraulically operated valves provide a minimum restriction to flow and reduction of turbulence. They are controlled by a "Stager" to backwash the filter and return it to service without any manual attention.

Timer/Controller

The standard method of control for automatic industrial water filters is accomplished through the use of a heavy-duty stager with an integral clock timer. This control has a built in manual override feature should backwashing be required at times other than at its pre-determined time.

TYPICAL BHS PROCESS REACTIONS WITH FILTRATION, WASHING AND DRYING TESTS Here is a summary of the technical information related to the lab mixing and testing of aquous raw materials of precipitated reaction solids and Pyridine, which forms a slurry.

Desired Deliverables from BHS Process & Filtration Lab Testing Applicable slurry characteristic data such as drying curve, chemical properties, etc. BHS Report that recommends optimum thin-cake filter technology and scale-up Path forward actions for on-site rental system

Timing for Lab Testing Three weeks from receipt of reaction chemicals and all operating data

Raw Material Quantities Precipitated Reaction Solids by BHS Required pyridine by client

MSDS Information The MSDS are provided under separate e-mail attachments.

TECHNICAL PROCESS OVERVIEW: Titration Reaction Precipitated Reaction Solids (aqueous) + Pyridine --------> Slurry

Use stoichiometric amount of pyridine Reaction is run at mild conditions (mixed batch reactor at ambient temperature) under inert nitrogen atmosphere. Reaction in a 6 L vessel; reaction rate is essentially instantaneous. Mild exothermic temperatures rise based on lab studies; the temperature rise is mainly attributed to heat of mixing. Reaction solids precipitate out of solution as a solid. About 10% solid solution from reactors

Recovery of solids by Thin-Cake Pressure or Vacuum Filtration The agglomerated and individual particle size distribution by BHS Agglomerated d50, d80 and d97 Individual particle size d50, d80 and d97 Depending on method of isolation of solids, wet cake will be between 30-50% solids and very sticky and pasty Dried product is easy to handle and does not appear to dust very much

Precipitated Reaction Solids Wash Wash excess NaOH, NaCl, free Pyridine and other components from the solids. Wash water to be 40-50°C in order to meet chloroform-insoluble specification. Extremely acidic wash water should be avoided to prevent product decomposition. Target pH on final water exiting wash is pH = 7-8.

Aqueous Waste Disposal: Waste will be generated due to washing to meet target pH. The aqueous waste composition is estimated to contain Water, NaOH, NaCl, and Pyridine and trace amounts of other solvents All waste will be shipped back to client for aqueous waste disposal.

Drying Target dryness of maximum 1.0 wt % water. Product is microcrystalline and does not aggregate when dry. The solid has good flowability when dry. To prevent concerns around flammability with pyridine (FP = 20°C), drying should be done under a nitrogen-blanketed atmosphere. The drying temperature to be below 100°C (Maximum temperature = 150°C).

BHS Summary Report Summary Test Purposes Test Methods Test Facilities Test Data Test Results 6.1 Filtrate Quality 6.2 Filtration Time 6.2.1 Filtration Time vs. Feed Volume 6.2.2 Filtration Time vs. Pressure 6.2.3 Cake Height vs. Feed Volume 6.3 Cloth Blinding 6.4 Cake Discharge

Selection of Production Equipment and Scale-Up Conclusions and Path Forward Actions For further information about BHS process reaction and filtration testing capabilities, please contact the BHS process department or visit www.bhsfiltration.com. You can also visit our BHS partner www.chdtechnologies.com. CHD specializes in consulting for the development and improvement of existing chemical plants, manufacturing processes and unit operations, hands on process simulation and improvement studies and testing and selection of specific applications in cooperation with BHS-Filtration Inc.

Industrial Netting offers a wide variety of mesh materials for filtration applications. The products are used across a broad range of industries including automotive, HVAC, water purification, hydraulic filtration, fuel filtration, beverage filtration, medical filtration, and food processing.

Polypropylene is a common resin in filtration applications due to its inert nature and regulatory approval for both food contact and pharmaceutical applications. Click on Plastic Mesh or Metal Mesh to view raw material choices, samples and specifications. Below are tables showing the common polypropylene extruded products used for filtration applications.

Extruded Netting distinct from woven and nonwoven materials. They feature greater dimensional stability and rigidity, as the joint structure is welded together. Extruded netting is produced in both Diamond (B-Planar) and Square (Mono-Planar) configurations. Both configurations are produced in rolls and made available in rolls or cut sizes. The Square mesh configuration is also produced in rigid tubular form.

Plastic netting is used to support the filter medium substrate. It helps the medium to retain a given shape or support the medium against the liquid or air stream. One major application for plastic netting is as a pleat support. It allows for relatively uniform separation between the pleats. Plastic netting is rigid enough to keep the pleats uniformly exposed to the stream, enhancing the filters' efficiency.

Plastic netting is used to support the filter medium in non-pleat applications as well. In disk filters, small aperture netting is used to create a separation between layers of filter media, ensuring the filtration stream has adequate exposure to the filter medium. More open aperture netting is used in air filtration panels to physically support the filter medium and as face plates to protect the filter media. Heavier weight, large aperture netting products are often used as backers in sewn filter fabrics for a wide variety of industrial filtration applications. Wherever, and however, filter media requires support, there is a plastic netting product that can help ensure its performance.

A major roll for plastic netting in filtration applications is to facilitate the flow of fluids or air across the medium. Plastic netting serves as a spacer between layers of filter media in a number of element configurations, allowing fluid to be channeled across the filter medium. The largest application for this flow channel function is with spiral filter elements. The Square configuration is used to add integrity to the media and is used as a pleat support or as a prefilter in normal flow applications. Square mesh gives consistent quality to the filter. The design of the netting provides for varying heights of the strands, creating the channel for fluids or air to flow. The Diamond configuration is used in cross-flow applications to provide drainage and as a spacer net. Due to its high profile strand construction it can provide support for the medium with minimal contact with the substrate, which reduces the effects of binding. The flow channel height and depth can be designed for various types of filtration streams and flow rates. While this is commonly used in spiral filter elements it is also used in other membrane-related filtration applications as well.

Flat stock plastic netting, rigid tubes and flexible netting sleeves can be used as an outer containment for cartridge filters. Netting can simply serve to protect the filter medium during handling and cleaning, or it may additionally serve to contain the filter medium in high pressure or inside-out flow applications. Whatever the function, extruded plastic netting, tubes and sleeves contribute to both the performance and aesthetics of a filter element.

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From the simplest of cloth filters to more complex integrated systems with two or three filtration stages, the Losma Liquid Filtration Range is made up of various types of filter to cope with all eventualities.

This series evolved as a result of the advances made in machine tool technology. It is Losma's response to the advent of high pressure cooling (HPC). The central core of guaranteed filtration is generally preceded by pre-filtration stages (magnetic and/or fabric) so that the lubricant/coolant has the assured levels of purity required for precision machining with tolerances down to tenths of a micron.

The RIVER series is available with high-pressure return pumps (up to 100 bar), filtration levels to 5 microns and flow rates from 25 to 100 litres per minute when working on neat oil. They are supplied with sophisticated systems for control and safety. Routine maintenance can be carried out without any machine downtime.

The Smith & Loveless FIBROTEX^® IronMan^TM System — a uniquely designed iron and manganese removal system that combines the FIBROTEX® filter with an integrated oxidation system — is particularly useful for municipalities and facilities that rely on well water sources for potable water. It economically precipitates and removes iron and manganese from well water and provides effective filtration.

Whereas conventional depth filters have a high solids-holding capacity and are usually backwashable, they suffer from the disadvantage of having a relatively coarse nominal filter rating. Cartridge filters, on the other hand, have a fine filtration rating, but have a low solids capacity and are generally not self-cleaning. The FIBROTEX represents a unique combination of the benefits of both types of filter in that it is an automatic backwashable depth filter with a higher solids capacity and a fine filtration rating.

FIBROTEX technology combines an expandable-bed fibrous filter element and an integrated oxidation system with a PLC. This enables the fibrous filter both to efficiently backwash itself automatically when fully loaded with solids, and to achieve exceptionally fine levels of filtration.

FIBROTEX offers a significantly better filtrate and backwash efficiency and a much smaller footprint (75% less typically) when compared to sand and other multimedia filters. Backwash water acts as a carrier to remove the displaced particulates rather than as the primary cleaning agent as in other backwashable depth filters. As a result, backwashing is highly efficient and requires a low volume of backwash water. Backwash rates are typically less than 2% of the filtrate and last only for a few minutes. Employing multiple units allows for continual flow and operation 24 hours a day with standby capacity available – even during backwash cycles.

A single FIBROTEX filter unit can handle flow rates up to 100 gallons per minute from well water sources. Multiple units can be configured in parallel for rates up to millions of gallons per day.