General Description

The electrically heated screw processor was developed because of the need to physically separate volatile and semi-volatile contaminants from soil, sediment and sludge. This is accomplished by heating to a temperature high enough to volatize the organic contaminants without the use of incineration. Previously dewatered sludge is heated in a chamber in which water, organic contaminants and certain metals are vaporized. A gas or vacuum system transports vaporized water and contaminants to an off-gas treatment system. The design of the system aims to volatize contaminants, while avoiding oxidization.

The electrically heated Screw Processor is an on-site skid mounted thermal dryer designed differently from a hollow screw processor. This unit is capable of heating waste streams between 320ºC - 560ºC (600ºF – 1,000ºF) sometimes in combination with solidification/ stabilization, or dechlorination, depending on the site requirements.

Electrical heating elements contained within the hollow core of the screws are operated to heat the screws evenly at a controlled rate. Thermocouples are installed at the discharge end of the processor, which measures the material temperatures at the specified location. The equipment is designed airtight with nozzles for possible injection of an inert gas such as nitrogen to limit the oxygen content.

The housing is totally insulated for minimal heat loss. An adequate number of vapor ports are installed in order to collect the off-gas emissions generated during system operation. Treatment of off-gas must remove particulates and contaminants using fabric filters and carbon adsorption procedures.

A hydraulic motor is installed at the feed end, drives the screws at a controlled rate. The motor is designed to have an adequate torque capacity capable of starting the screws even when it is loaded with material.

The material of construction exposed to heat and product is generally 304 stainless steel. The screw flights are generally equipped with 1/8” thick hardface overlay to minimize wear on the flights.

Therma-Flite can also manufacture the entire system consisting of twin-screw ribbon flight feeder equipped with a loading hopper as shown in the picture above. The entire feeder is mounted on load cells to monitor material flow. The heated material coming from the electric screw is transferred to a “HOLO-SCRU” Twin unit for indirect cooling. All three pieces of equipment are connected through a series of mating flanges designed for easy disconnect.

Soil Remediation:

1. Dry or Decontaminate sludge and soil onsite
2. Combat the high cost of incineration
3. Eliminate permit problems associated with incineration.
4. Meet EPA requirement
5. No after burning
6. No catalytic combustion
7. Cost effective
8. Easy to move and install
9. Heating capabilities run from 80 to 1000 degrees Fahrenheit
10. Can be built to be operated under a vacuum