International Fuel Cells, LLC

United Technologies Corporation

Herbert C Healy

John C Trocciola

Roger R Lesieur

Ronald J Spiegel

Richard A Sederquist

Alexander H Levy

Gregory J Sandelli

Matthew Kolodney

The effluent gas stream from anaerobic waste water treatment digesters is treated to remove trace amounts of hydrogen sulfide and other contaminants. The chemical equation involved relies on the reaction of hydrogen sulfide with oxygen to form water plus elemental sulfur. The removal system includes a variable control line for adding air to the effluent gas stream; a filter for removing solids, entrained liquids and bacteria from the oxygen-enriched gas stream; a blower for directing the filtered gas stream into a potassium promoted activated carbon bed wherein the above chemical reaction takes place; and sensors for measuring the content of oxygen and hydrogen sulfide at the entrance and exit of the activated carbon bed. When the hydrogen sulfide content of the exiting gas stream exceeds a predetermined level, the amount of air added to the gas stream is increased until the predetermined level of hydrogen sulfide is achieved in the exiting gas stream.

Removal of hydrogen sulfide from anaerobic digester gas

The gas stream which emanates from landfills is treated to produce a purified gas which is essentially a hydrocarbon such as methane which can be used as the fuel source in a fuel cell power plant, or can be used in other power plants which use natural gas as a fuel. The landfill gas passes through a system which removes essentially all of the hydrogen sulfide; water; organic sulfur and halogen compounds; and solid contaminants from the gas stream. The resultant purified gas stream can be cleanly flared; used to power an energy plant; or put to other useful purposes.

Landfill gas treatment system

A gaseous mixture of hydrogen and carbon dioxide is used as the fuel cell fuel or anode gas, and air is used as the oxidant or cathode gas in a nonalkaline fuel cell power plant. In feeding the fuel gas through the anode side of the fuel cell, hydrogen is removed during the electrochemical reaction and the fuel gas which is exhausted from the anode side has a much higher proportion of carbon dioxide to hydrogen than the entering fuel gas. The fuel gas exhaust is fed through a carbon dioxide absorber to remove carbon dioxide from the fuel exhaust. The carbon dioxide is recovered from the absorber for useful purposes and the hydrogen gas leaving the absorber is dewatered and burned in a reformer. Carbon dioxide emissions from the power plant are thus greatly reduced benefiting the environment.

Recovery of carbon dioxide from fuel cell exhaust

To avoid using high quality heat to boil water condensed from a moist gas stream and to increase the overall thermal efficiency in a system requiring a supply of steam obtained by boiling water condensed from a moist gas stream, the condensing of the desired amount of water is done in a combined condenser/boiler wherein the condensed out water is separated from the gas stream, reduced in temperature, and throttled to a pressure wherein it is converted to steam back in the condenser/boiler using only the heat of condensation and sensible heat from the moist gas stream during the condensing step.

Growing community of inventors

Hebron, CT, United States of America

Herbert C Healy