CHEMICAL LOOPING SYSTEM FOR REDUCING EMISSIONS FROM A COMBUSTION GAS
Publication Date: 2016-Mar-11
The IP.com Prior Art Database
The invention proposes a system for reducing emissions of a combustion system and more specifically, to a chemical looping based system for oxidizing partially-oxidized gas species of a combustion gas. A chemical looping system for oxidizing gases comprises a combustion system and a regenerative heat exchanger. The combustion system combusts a fuel that produces a flue gas containing partially-oxidized flue gases. The regenerative heat exchanger includes a heat exchange elements, a first inlet and a second inlet. The heat exchange elements include an oxide material for capturing and releasing molecular oxygen in a cyclic manner. The first inlet is configured to receive an air stream to capture molecular oxygen on a first portion of heat exchange elements, and a second inlet is configured to receive the flue gas from the combustion system to oxidize the partially-oxidized flue gases.
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CHEMICAL LOOPING SYSTEM FOR REDUCING EMISSIONS FROM A
The present disclosure relates generally to a system for reducing emissions of a combustion system and more specifically, to a chemical looping based system for oxidizing partially- oxidized gas species of a combustion gas. Combustion systems, such as boilers and chemical looping systems, combust a hydrocarbon-containing fuel such as coal, petcoke, biomass, natural gas therein. Depending on the combustion efficiency, the flue gas is released from a combustion system, for example an air-fired boiler, firing any hydrocarbon-containing fuels contains different amounts of undesirable partially oxidized gas species, such as CO, H2, CH4, H2S, etc.
Flue gas streams from fossil fuel-fired boilers often contain excessive amounts of unburnt gaseous species that need to be controlled in a cost-effective manner. The reduction of the emissions of theses partially oxidized gas species is desirable to lessen the harm to the environment. No practical system is available for combustion of these species at a low temperature. Emissions of these species have to be controlled. A simple system is desired to reduce emissions of these species. Existing solution for reducing unburnt gaseous species is to feed excess amount of air to ensure complete combustion. This implies larger equipment and lower thermal efficiency.
Regenerative heat exchanger systems (e.g., Ljungström air heater or Rothemühle air heater) are widely used in fossil fuel-fired steam boilers for improvement of thermal energy utilization. In a regenerative heat exchanger system, thermal energy is transferred from flue gas to combustion air by first exposing heating elements to a high-temperature flue gas in the flue gas duct and then to ambient air in the combustion air duct. The exposure is in cyclical fashion. The cyclical exposure is realized by having the cylindrical heating element- containing component, the rotor, rotate between the flue gas and air ducts (Ljungström approach). The cyclical exposure can also be realized by having the duct system (hood) rotate around heating elements (Rothemühle approach).
The invention discloses a chemical looping system for oxidizing partially-oxidized gas species of a combustion gas that includes a regenerative heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention discloses a chemical looping system for oxidizing partially-oxidized gas species of a combustion gas, wherein:
FIG. 1 is a schematic diagram of a power plant including a boiler having a regenerative heat exchanger system in accordance with the present invention.
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FIG. 2 is a perspective view of a regenerative heat exchanger in accordance with the present invention.
FIG. 3 is a schematic diagram of a chemical looping combustion system including a regenerative heat exchanger system in accordance with the present invention.
FIG. 4 is a plot the gas composition of a cyclic reduction-oxid...