Poroplate MaxPore Extended Area Filters For Chemical Processing Applications. (full
The chemical processing industry is one of the world’s largest users of industrial filtration equipment. Filters are used in a wide range of liquid process applications in chemical plants, including filtering the raw materials, additives/pigments/catalysts, water/liquid waste generated by the process, and the finished product itself.
The most commonly used filters in the chemical processing industry are bags and cartridges. These are typically constructed of cotton, synthetic polymers, fiberglass, or other non-metallic media. While acceptable for most applications, they are generally not suitable for temperatures above 400-500˚ F (except for fiberglass, which is capable of higher temperature exposure), and are incompatible with some chemicals. Therefore, alternative materials of construction must be used in many cases.
While the initial cost of the above noted bags and cartridges are very low, the total cost of use can be very high. Factors such as labor to change-out filters, production loss during change-outs, operator exposure to potentially hazardous chemicals during change-outs, and cost to properly dispose of used filters should be considered.
Considering the chemical compatibility and temperature limits, as well as the total cost of use of non-metallic filter bags and cartridges, reusable porous metal filters are often the best choice for chemical processing applications. But, in order for porous metal filters to be economically viable, they must be capable of economical regeneration in situ, or economical external chemical cleaning must be available.
Purolator Advanced Filtration recently introduced a technology that addresses these challenges. Poroplate® MaxPore™ extended area filter baskets have been specifically designed for high temperature, corrosive environments, and can be cleaned in place for reuse, or removed and chemically cleaned.
Poroplate MaxPore baskets are constructed from stainless steel (or higher alloys) sintered wire cloth laminated media (Figure 1). This media has a 40+ year proven service record in a variety of high temperature, high pressure and corrosive applications, and is available in ratings as low as 2µ nominal. The media consists of multiple layers of woven wire cloth, which are diffusion bonded (sintered) in a furnace to create a highly permeable filter laminate with a permanently fixed pore size. The media can be configured as a surface media, or as a progressive pore size media, which yields up to 4x higher dirt holding capacity. Both configurations can be backwashed/back-pulsed to regenerate the baskets.
After the media has been constructed in panel form, it is cut/formed/welded into various diameter cylinders, which are concentrically arranged to maximize the effective filter area. Each of these cylinders consists of an inner and outer cylinder, open on one end and joined together by a solid ring at the other. A flow channel is created between the inner and outer walls of each cylinder, similar to the flow path of a wall flow filter. This dual-sided arrangement further increases filter surface area. In its final form (Figures 2 and 3), the Poroplate MaxPore extended area basket has up to 23 ft.2 of filter area and fits into a basket housing that would normally hold a single filter basket with only 4 ft.2. This advantage in effective filter area can be used in several ways — to reduce the number of filter housings/valves/piping needed in new installations, to increase filter life, to reduce pressure drop, and to increase the flow rate through the filter.
A typical Poroplate MaxPore basket is capable of flow rates of up to 300 gpm (of water or fluid of an equivalent viscosity) with a clean pressure drop as low as 1 psi.
Poroplate MaxPore baskets can be used in standard bag/basket housings where they can be removed for cleaning when dirty, or cleaned in place. The preferred flow direction is from the bottom of the basket up and through the media, then out the top of the basket. Cleaning in place is typically accomplished by reversing the flow and pushing clean, filtered liquid back through the media with approximately 100 psi. The pressure can be applied by air/gas, or the clean liquid itself.
The chemical processing industry today has a number of filtration products to chose from, and the final selection of which type to use in each application should be determined by a number of factors, as mentioned earlier in this article. The initial cost, as well as the total cost of use must be considered.
Poroplate MaxPore extended area filter baskets have many unique performance characteristics such as high flow rates with low pressure drop, filtration ratings as low as 2µ, ability to be regenerated, compatibility in applications with high temperature, high pressure, and corrosive chemicals. These characteristics should be considered when making the final selection for chemical processing applications.