Sizing A Filter Press

One of the most common questions we receive from potential customers relates to the filter sizing process for our filter presses.  Automatic Filter Presses have proven themselves to be incredibly versatile and have a wide variety of industrial applications.  These filters are important parts of the manufacturing process for thousands of our customers around the world, in a multitude of industries.  From mineral processing at mines to municipal waste to biodiesel production, filter presses have proven themselves useful over decades of use.

Excellence Through Testing

We believe that testing is the most important part of the sizing process, which we do prior to the design phase.  Properly sizing a filter press is accomplished by testing product slurries using a direct representation of the full scale filter.  This simple step has been incredibly useful in eliminating many future problems, including wasteful spending on overly large equipment, as well as production issues associated with undersized equipment.

The first piece of information our team of engineers needs when sizing a filter press is the mass of dry solids in the system.  A representative sample is needed to find the dry solid mass in slurry.  We first weigh the sample and place it in an oven to dry.  When all of the water has evaporated, we reweigh the sample. The difference in masses tells us how much water was in the sample and the ratio of solids to water.  Running a filtration test allows us to determine the time a filter will take to run one cycle and the amount of slurry the filter is able to efficiently process.

We believe that testing allows us to plan ahead and deliver the best finished system for our end customer.  We have bench scale Verti-Press tower filter presses that are used to size filters for new applications.  Cake conditions and cycle times are optimized, so that the correct press size (measured in filtration area) can be implemented.  This testing process allows the team to learn all of the wet and dry cake characteristics, and the cake thickness limits prior to production.  If needed, cake wash water volumes and cycle times may also be analyzed to prove solids purity.  This thorough testing process allows us to achieve excellence and minimize problems that can occur on site.

The bench scale Verti-Press sizes a full scale unit by using a simple equation to scale up.  The common formula to do this is:

(m_b)/[(A_b)*(t_b)/60] = (m ̇_f)/(A_f)

Where:

m_b = dry mass of bench scale filter cake (lb)
A_b = area of bench scale filter press (ft3)
t_b = time of test cycle (minutes)
m ̇_f = dry mass to be processed (lb/hr)
A_f = area of full scale filter press (ft3)

Different types of media may also be investigated in order to find the one most suitable for the job.  The best filter belt to use will be tight enough that there is no particulate in the filtrate and will be rugged enough to last for many cycles.