THE MACHINE

Filter Press is a machine used for solid-liquid separation. Its working principle is based on the pressure filtration, wherein the sludge / slurry is pumped into the filter press and the solids are retained in the press (known as cake) and the solids-free liquid (known as filtrate) separates and flows out of the filter press under gravity. The slurry is fed under pressure via a feed pump which could be centrifugal or screw or peristaltic or any positive displacement pump. The differential pressure causes the filtration to occur thus leading to solids being captured on the filter cloth (placed over a recessed filter plate) thus forming a solid cake. Simultaneously, the clear filtrate keeps flowing out of the machine, which is almost devoid of solids. On reaching a choke-point wherein the filtrate flow stops / trickles down to almost no flow; many a times signals the complete cake formation & thus completion of a batch.

The filter press is a ‘batch’ pressure filter, referring to the cyclical process where the feeding is interrupted to dislodge the cake, afterwhich another batch is started. By installing two machines in parallel, the filter press operation could be made continuous where the feed is diverted to the other machine during cake discharge of the 1st and synchronising the timings of both machines very precisely.

Filter Presses are efficient machines operating at low running costs offering a large filtration area in lesser footprint, thus capable of handling very large volumes in comparison to similar type of machines.

We, at Dinshaw, design your filter press to the best size in terms of filter plate size, number of chambers, type of mechanism based on factors like slurry flowrate, solids loading, outlet consistency, operating hours and bring our years of experience to provide an efficient filtration solution.

THE PROCESS

On filter press closure, the empty chamber formed between the plates is shown alongwith the empty membrane chamber.

When the slurry flow starts, the cake starts getting formed in the chamber gradually, thus pushing behind the membrane diaphragm. Filtrate flow starts.

Cake washing is initiated with the fresh wash water entering from the top nozzles. The water then passes through the cake & comes out through the bottom nozzles.

After the cake is formed, the membranes are inflated by passing water which in turn exerts pressure on the cake, thus squeezing out the extra moisture.

Core Blow sequence is initiated which is basically passing of air from the last plate in the core i.e. centre hole to remove the loose / shallow slurry left.

The membranes are then deflated by reversing the flow of water back to the water tank.

The filter press is now opened thereby allowing discharge of the well dried cake.

APPLICATION