In this FAQ section, we answer the most frequently asked questions about filtration and drying. Benefit from our expert knowledge and find the right solutions for your specific needs in chemical and pharmaceutical production.
Filtration
We have a batch process that would benefit from being upgraded to a continuous process. What would BHS recommend?
The BHS rotary pressure filter or continuous-indexing vacuum belt filter are solutions to this process problem. Please submit the application data sheet and one of our application sales engineers will contact you to begin the process discussions.
How can we test for thin-cake filtration?
The BHS pocket leaf filter (PLF) is ideally suited for laboratory tests. The PLF can be used to test thin-cake filtration for pressure or vacuum operation. It is jacketed so hot (150 º C) filtration or cold filtration can be tested. Different cake thickness and different filter media are also included as the test parameters. Finally, cake washing and drying can also be tested on the PLF. BHS conducts these tests in our process laboratories in Charlotte, NC or at your facility.
Can cake washing be conducted on BHS filters?
Yes, all BHS filters provide a cake washing process step. With thin-cake processing, cake washing, especially displacement washing, is very efficient, as described in the “Cake Washing” article.
How is the cake discharged from the BHS filters?
The BHS filters all use different discharge techniques depending upon the filter technology, the characteristics of the cake and the specific process and downstream equipment at your plant. As a general overview, the BHS technologies offer automatic discharge, complete discharge with no residual heel and full containment to eliminate operator exposure. Cake discharge can be a wet cake, dry cake or a slurry.
How do our engineers categorize the BHS filters?
The BHS filters are categorized as thin-cake technologies. The units can handle applications from high solids (up to 60%) slurries to clarification for slurries with trace amounts of solids. They can be pressure or vacuum filtration for continuous or batch operations. The BHS process engineers are experts in determining the optimum technology for your application.
What applications are the best for the BHS thin-cake technologies?
The BHS technologies have been installed in many industries since the 1950’s. We serve four general marketplaces: chemical, food & pharmaceutical and energy & environmental.
We use centrifuges, nutsche filters, filter presses as well as manual plate filters, bag filters and other conventional separation equipment. What would BHS recommend to improve our operation?
All of the BHS pressure and vacuum filtration technologies are alternatives for your current equipment. Once we know the percent solids in the slurry feed as well as several other process parameters, we can assist your team. Please contact us and one of our application engineers will be happy to discuss your requirements with you.
What materials of construction can be used for your filters?
Our filters can be closed, dust-tight or pressure-tight for inerting or various gas explosion zones. They are made of various stainless steels, Hastelloy, synthetic or reinforced synthetic materials, depending on the solvents, solids, temperatures, etc.
BHS completes the turnkey systems with feed pumps, liquid feed and return pumps, separator and collection tanks, liquid ring vacuum pumps, instrumentation, prefabricated and wired skids and PLC control systems. Heating and cooling packages for liquids and/or gases as well as solids handling can also be integrated.
Drying
Does BHS offer conical dryers with NAUTA mixing screws?
No, although orbital screw systems are still occasionally used in the industry, they are no longer state of the art. Thanks to the special BHS mixing helix, treatment times can be reduced by up to three times compared to orbital screws. In addition, almost all maintenance and servicing costs are eliminated, as reversing gears and systems are no longer required. Another advantage of the helix system is the possibility of using choppers, which is not possible with an orbital screw.
Does BHS offer dryers or reactors with ploughshare blades?
For many years, BHS has relied on specially adapted shovels, optimized versions of the so-called Becker shovel. These special mixing elements enable lower mixer shaft speeds compared to ploughshare tools, which significantly reduces wear on the mixing shaft seal, bearings and mixing elements.
In addition, they offer further advantages, such as improved residual discharge, more flexible adaptation to different products and processes and more precise adjustment of dwell times in continuous systems. Thanks to optimized manufacturing processes, these shovels are also more cost-effective than conventional ploughshares.
If ploughshare shovels are favorable from a process engineering point of view, e.g. for the cellulose reactor, they are used. Furthermore, stud shovels are perfectly suitable for products which tend to stick on the wall.
Is BHS-Sonthofen the successor to AVA-Huep GmbH?
Yes, BHS-Sonthofen acquired all shares in AVA-Huep GmbH from Herrsching am Ammersee in 2018. Since then, the company and its products have been an integral part of the Process Technology division.
Why does BHS use vacuum in many drying processes?
Low process pressure lowers the evaporation point, allowing temperature-sensitive products to be dried particularly gently. Vacuum drying is also a more energy-efficient solution than processes which are carried out under ambient pressure or slight underpressure.
Can highly viscous products be processed with BHS dryers and reactors?
BHS paddle dryers are characterized by a high mixing intensity and can also mix and dry very viscous products thanks to their unique mixing unit.
Are BHS machines suitable for ATEX applications?
Yes, for ATEX applications we always carry out a risk analysis at the start of the project, in which the hazards and the corresponding protective measures are defined. For example, the product areas can be inertized, the components are designed in accordance with the required device category, or the effect of an explosion may be limited to a safe level by constructive design. This reduces the risk to a minimum.
Does BHS offer turnkey system solutions for drying and reaction technology?
Yes, BHS supplies dryers and reactors with all the necessary components on request, including vacuum pumps and condensate separators for vacuum operation. A fully automatic control system ensures safe and efficient operation.
Can BHS systems be monitored remotely?
Yes, BHS control systems can be equipped with integrated routers that enable remote maintenance and diagnostics. This means that cost-intensive on-site visits can often be avoided.
Are BHS conical dryers and paddle dryers used in the pharmaceutical industry?
Yes, the machines comply with cGMP guidelines and can be operated up to exposure class OEB 5 (0.1-1 µg/m³). They are also equipped with WIP and CIP systems.
What are the advantages of contact dryers compared to convection drying?
The exhaust air flow is limited to the leakage value of the machine, so that it can be used without any problems in accordance with BImSchG. There is no need for time-consuming and costly treatment of the drying gas, which reduces both the required installation space and the operating costs.
Are BHS machines also available in special materials?
Yes, in addition to carbon steel and common stainless steels, the dryers and mixing reactors are also available in special materials such as nickel-based steels (Hastelloy), duplex steels, zirconium or titanium.
Which pressure equipment directives does BHS apply?
BHS offers systems in accordance with the Pressure Equipment Directive 2014/68/EU as standard. However, other regulations can also be taken into account on request, including the European harmonized DIN-EN 13445, the American ASME U-Stamp Code, the SELO approval (China Stamp) or the Korea Stamp.