Endurance testing of outboard motors for boats was typically done in lakes and sometimes on barges. It was time consuming and presented logistic problems and numerous other challenges for the research and development department at outboard motor factories. When a company in Oklahoma decided to build their own endurance test cell area, the Environmental Protection Agency (EPA) required them to control the emissions from the test engines. Four test cells were considered for air pollution abatement. The initial design exhaust volume was in excess of 4,400 SCFM (6,940 Nm3/Hr) per test cell. This high exhaust volume per cell posed a significant capital and operating cost problem when the company considered pollution control equipment.
The company believed a thermal incinerator would be the preferred solution because of the low cost of natural gas in Oklahoma. After looking at equipment capital cost and operating costs they recognized the benefit of considering a catalytic oxidizer. After thorough technical evaluation, The customer chose Anguil Environmental Systems to solve their VOC problem and ensure that the new test cells were in EPA compliance.
Automotive catalysts have proven effective in handling exhaust gases from internal combustion engines, where both un-burned hydrocarbons and carbon monoxide are destroyed. Anguil analyzed the operation and concluded that the enclosed engine test cells needed significantly less exhaust volume than the 4,400 SCFM (6,940 Nm3/Hr) proposed. Anguil determined that the exhaust from even the largest stern drive engine was under 800 SCFM (1,262 Nm3/Hr) of air. It was critical for this to be under negative pressure, so no carbon monoxide would leak into the test facility. Using 850 SCFM (1,341 Nm3/Hr) as a design criteria, Anguil determined that a 6,800 SCFM (10,725 Nm3/Hr) catalytic oxidizer could handle the initial four test cells with the additional capacity for four future test cells.
Anguil supplied and installed the catalytic oxidizer inside the building on a mezzanine adjacent to the test area. Anguil supplied only enough catalyst to handle the initial loading from four test cells, which reduced the initial capital cost. Anguil engineers performed an exhaust stack test analysis to determine what concentration of carbon monoxide and hydrocarbons was present. The presence of carbon monoxide dictated a total enclosure around the catalytic oxidizer. Anguil placed an exhaust fan in the enclosure, creating negative pressure and eliminating the possibility of carbon monoxide leaking into the facility. The oxidizer was equipped with a variable speed/variable frequency drive to provide a high degree of turndown if only one test cell was being run. A stainless-steel plate and frame type heat exchanger was used to accommodate high exotherm across the catalyst.
Some of the engines in the facility were diesel engines and some endurance runs were lengthy. Since these engines potentially could go out of tune, a ceramic particulate filter was installed within the catalytic oxidizer down-stream of the gas burner to protect the catalyst from unburned carbonaceous materials. The periodic cycling and high fire of the gas burner eventually vaporizes these carbonaceous materials and allows them to be oxidized by the catalyst.
After approximately eight months of successful operation, the company decided to expand and add the four additional test cells. The new exhaust fans and ductwork were completed by Anguil’s installation crew and additional catalyst was added to meet the company’s increased capacity. The result is a state-of-the-art engine test facility in compliance with EPA requirements.