News & Events

Radial Cartridge Application Success in Whiskey Filtration

Recently a trial was conducted at a distillery in the US. For those of you not familiar with whiskey, except in a glass (or for those trying times, directly out of a bottle), the product is produced from a mash of grains, fermented from 3 to 5 days, distilled and then aged in barrels for four to seven years. After the aging period, the whiskey is removed from the barrels and typically filtered through plate and frame or Pressure leaf filter, then mellowed and filtered a second time, polished with a higher filter technology, and finally bottled. The bottling process typically operates 24/7, with up to 100,000 gallons produced in a day.

In this particular facility, a large Pressure leaf filter was utilized (33 inches in diameter and 50” high). This assembly is placed inside the housing utilizing a hoist. When plugged, this assembly must be removed from the housing, disassembled, cleaned and reassembled, which is a labor intensive process. In addition, diatomaceous earth is used as a filter aid, which is becoming a potential environmental and health concern throughout the world.

The concept was to test the Porex Radial Cartridge Filter as a potential replacement for the Pressure leaf system. The 5 and 10 micron Radial Cartridge filters would be tested in a small test stand using the same whiskey that was being filtered through the Pressure leaf. The goal was to achieve an equivalent turbidity reading, which ranged from 1.2 to 2.3 NTU. The backwash ability of the filter would be evaluated, and was required in order to justify the economics of replacement.

The test stand consisted of a 10” 226 housing plumbed for forward flow and valved for backwash. Water was used for backwash and was supplied from the house system at about 70 psi. The initial flow rate on the 10 micron was chosen at about 3 gpm per square foot of surface area, or about 6 gpm. The differential pressure was determined by a gauge on each side of the housing, which was believed to have about 6 pounds of drop as valved. The flow rate on the 5 micron was chosen based upon the differential established from the test of the 10 micron (about 8 psid), yielding a flow of about 2.5 gpm per square foot of surface area. In each case, the differential pressure was allowed to increase until the available fluid was gone or 30 psid, whichever came first. Upon termination of the test, the inlet and outlet valves were closed and the backwash outlet valve was opened. The backwash inlet valve was then opened until the effluent was clear (about 3 – 5 second), then shut off and repeated two more, brief times, creating a back pulse. The system was the started as whiskey was available and the initial pressure drop monitored.

The goal of the test was to identify the correct filter to achieve a turbidity reading suitable for the application as well as show the backwash ability of the Porex Radial Cartridge. The test data showed that the 5 micron filter will yield turbidity results that approximate the performance of the DE/Pressure leaf filter currently in use. The trial also supports the belief that the Porex filter can be backwashed repeatedly, returning to essentially the original clean value. Subsequent studies will be done at a larger scale to scale up the system.