April 23, 2009 ISSUE #210
Pea cannery operations generate a lot of waste which is screened from their wastewater. Generally the flow is pumped over static (sidehill) screens, which separate a sopping wet mass, mostly peas. These screen tailings must be trucked from the site.
Because the tailings hold so much water, the tonnage is significant. More importantly, free water jostles free in transport, leaving a trail of water behind the waste hauler.
Dewatering this waste is a good application for an inexpensive Series KP screw press. When the screen tailings are fed to the press, depending on the effectiveness of the static screen, from 60% to over 80% of the weight is separated as wastewater.
This press liquor does not contain an excessive amount of suspended solids. Regardless, it should be directed to the wastewater flow which goes to the static screens.
In one installation the cannery also has a flow of waste which is exhausted from the factory with a fan system. The discharge of the fan is blown to a chicken wire cage built over the inlet to the screw press. This waste, along with screen tailings, falls into the press.
The peas are so soft and squishy that low discharge cone pressure is used. The rotating cone feature is very important to successful operation. Also, the new two-thirds pitch screw has proven especially effective. With these options, high press screw press capacity is achieved without pushing excessive solids into the press liquor stream.
In one application a 10" press worked fine on peas. However a larger 16" press was required, due to increased load, when the plant switched to canning corn.