Flue gas heat recovery and air pollution control

Simple in concept, FLU-ACE has accomplished something that many others have tried unsuccessfully to do for a long time, and they have plants that have been operating for over 10 years. Their condensing heat exchanger system replaces the stack in combustion systems, recovering almost all of the waste heat, and removing most of the emissions. With modifications, it even can remove up to 50% of the CO2.

It can be thought of as pollution control that pays for itself in fuel savings–or visa versa. Water is sprayed into the hot flue gas, both cooling and cleaning it. The water is then collected, passed through a heat exchanger to recover the heat, and treated to neutralize the acidity and remove contaminants.

Condensing heat exchangers aren’t new, but they normally can be used only when the hot gas is reasonably clean. FLU-ACE can handle any kind of gas, even if it contains particulates, acids and unburned hydrocarbons. Conventional wisdom holds that corrosion, plugging and clogging should defeat this approach, but FLU-ACE has overcome problems with its patented design. Systems show no degradation after years of operation. It has even been qualified for use with biomedical incinerator exhaust.

Industrial boilers and cogeneration plants are ideal applications. The installed base includes district heating systems, sewage treatment plants, hospitals, pulp and paper mills, and university campuses. Heat recovery is even greater when the exhaust gas is high in moisture content, e.g. in paper mills and sewage treatment. The largest system to date is 15 MW thermal, but there is no limit on the size.

A fossil power plant could use about 15% of the recovered heat for makeup water heating, so the economics are better when there are nearby uses for the heat. The company really wants to do a coal burning power plant–a slipstream demo could be the first step.

The company is a small publicly traded Canadian firm (symbol TMG – Alberta Stock Exchange). They have a dormant U.S. subsidiary, and are seeking U.S. partners, joint ventures and alliances for market expansion.

For further information:
Gustav Pliva, Exec. Vice President
Thermal Energy International Inc.
Neapean (Ottawa), Ontario, Canada
613-723-6776 Fax: 613-723-7286 E-mail: thermal@istar.ca
Web Site – http://www.thermalenergy.com/

(UFTO first reported on FLU ACE in October ’95)
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The following materials are excerpted from the company’s website:

The unique FLU-ACE technology is a combined heat recovery and air pollution control system, which recovers up to 90% of the heat normally wasted in hot chimney flue gases. FLU-ACE substantially reduces the emission of “Greenhouse Gases” (including C02), “Acid Gases” (including SOx), Nitrogen Oxides (NOx), unburned hydrocarbons (such as THC and VOCs), and particulates (such as soot and fly ash). It eliminates the need for a conventional tall smoke stack or chimney.

Thermal Energy International Inc. has built eleven FLU-ACE Air Pollution Control and Heat Recovery Systems in Canada. All of Thermal’s FLU-ACE installations in Ontario have been approved by the Ontario Ministry of Environment and Energy. The life expectancy of the FLU-ACE system is at least thirty-five to forty years. In December 1997, the company received patent protection in 42 countries; the US patent is expected early in 1998.

Low NOx FLU-ACE provides a payback on investment and is self financing from the savings that it generates for the industry user. The company is able to provide “Off-Balance” Sheet financing or 3rd party financing options for acquisition of its FLU-ACE technology by industrial and institutional buyers.

Using a direct-contact gas-to-liquid mass transfer and heat exchange concept, the system is designed to process flue gas from combustion of fossil fuels, waste derived fuels, waste, biomass, etc. The FLU-ACE System is configured as a corrosion resistant alloy steel tower at a fraction of the size of any conventional stack. All of the hot flue gas from one source or multiple sources (including co-gen and boilers) are redirected into the FLU-ACE tower, where it is cooled to within one to two degrees of the primary water return temperature, which enters the tower typically at between 16°C (60°F) and 32°C (90°F) depending on the season and outside air temperature. The heat (both latent and sensible) from the flue gas is transferred to the primary water which then reaches up to 63°C (145°F) and with special design up to 85°C (185°F), and circulated to various heat users.

FLU-ACE most sophisticated version (HP) reduces air pollutant emissions by over 99% including particulate down to 0.3 micrometers in size, and simultaneously recovers 80-90% of the heat in the flue gas normally exhausted into the atmosphere. This results in a reduction of fuel consumption by the facility up to 50%.

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