CDS Research Scrubber

Initially developed by TRIUMF research scientists, a novel cryogenic method of cleaning flue gas emissions was licensed to CDS Research Inc. (CDS), who further developed and patented the process, resulting in the scrubber unit. CDS is a Vancouver-based specialty engineering company whose primary focus is to provide consulting services to worldwide clients engaged in Liquefied Natural Gas projects. Recently, CDS developed a simplified version of the technology for application in greenhouses in the Lower Mainland of BC.

The CDS scrubber technology consists of multiple treatment modules designed to perform specific mitigation duties. The advantage of this process is its simplicity, flexibility and ability to adapt to a large variety of emissions. The scrubber unit is permanently connected to the vent stack of the boiler, and its controls are fully integrated with the boiler’s controls. Whenever the boiler is in operation, the flue gas is directed to the scrubber for clean up. The CDS scrubber is intended to filter particulate emissions and reduce NOx and SOx, but can also selectively trap other contaminants, such as mercury and/or arsenic. The process also eliminates the strong odours that are generally associated with burning sulphur-bearing coal. Every two weeks, collected particulate matter, including trace elements, is emptied and disposed of in accordance with British Columbia waste disposal guidelines. The units contribute significant fuel cost savings to the greenhouse operators.

 
Scrubber
The CDS Scrubber undergoing testing in Manitoba. Filtered wastes are collected into a bin shown here and prepared for disposal.
 

Recently, the Greater Vancouver Regional District (GVRD) has shown great interest in the CDS scrubber. The introduction of the scrubber unit is timely because greenhouse operators in the Lower Mainland are facing hardship due to increasing natural gas prices. The GVRD has been reluctant to allow, without scrubbing, the burning of alternate fuels to natural gas. To demonstrate that the unit would meet all the requirements of Environment Canada and the B.C. Ministry of Water, Land and Air Pollution, in March 2004, McCall Environmental, a company from Victoria, B.C. that specializes in testing output from smokestacks, was retained to conduct formal tests on a prototype unit. The rigorous testing of the unit compared the smokestack emissions with and without the scrubber for several different types of coal, plus wood chips and wood pellets. These tests were critical in providing initial data for both the B.C. Ministry of Water, Land and Air Pollution and the GVRD. The results showed that there were significant reductions in particulate and SOx emissions, some reduction in NOx, and considerable reduction in all trace metals emitted.

The scrubber introduces an innovative method of advanced clean-up technology that moves away from the conventional method of converting one form of waste from flue gas into another form of waste. Instead, potentially harmful effluents can be recovered as recyclable materials and introduced as feedstock into secondary industries. This allows for the use of significant coal energy still available today without the associated environmental penalties, due to the effectiveness of the integrated recovery and clean-up systems. The CDS technology involved may additionally be refined and applied to other combustion industries to further reduce emission levels.

The next step for the smokestack scrubber project will be to fine-tune the production model prior to production. To date, several units have already been ordered by eager customers. Funding for this project was provided by the National Research Council (NRC).