The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO.sub.2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO.sub.2 circulating fluid. Fuel derived CO.sub.2 can be captured and delivered at pipeline pressure. Other impurities can be captured.

The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO.sub.2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO.sub.2 circulating fluid. Fuel derived CO.sub.2 can be captured and delivered at pipeline pressure. Other impurities can be captured.

An apparatus and process can be configured for reduced nitrogen oxide formation during combustion. Embodiments can provide synthetic air to a combustion device so that combustion of a fuel can occur with a substantially low amount of NOx. Some embodiments can provide a reduction in NOx formation by at least 75% and as much as greater than 95% as compared to use of ambient air or oxygen enriched air oxidants. Embodiments can also provide a flue gas that has a high concentration of carbon dioxide that can facilitate improved carbon capture and permit efficient formation of at least one carbon dioxide product stream with a high carbon dioxide concentration (e.g. at least 95 mole percent carbon dioxide).

A gas separation process for treating exhaust gases from combustion processes. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

Disclosed herein is a method of controlling the operation of an oxy-fired boiler; the method comprising combusting a fuel in a boiler; producing a heat absorption pattern in the boiler; discharging flue gases from the boiler; recycling a portion of the flue gases to the boiler; combining a first oxidant stream with the recycled flue gases to form a combined stream; splitting the combined stream into several fractions; and introducing each fraction of the combined stream to the boiler at different points of entry to the boiler.

The present invention relates to methods and systems for controlling a combustion reaction and the products thereof. One embodiment includes a combustion control system having an oxygen supply stream and a high concentration carbon dioxide stream, mixing the streams to form an oxygenation stream substantially comprising oxygen and CO2 and having an oxygen to CO2 ratio, then mixing the oxygenation stream with a combustion fuel stream and combusting in a combustor to generate a combustion products stream having a temperature detected by a temperature sensor, the data from which is used to control the flow a carbon dioxide diluent stream to produce a desired temperature of combustion. The system may also include a control system configured to regulate the flow of the oxygen supply stream based on the flow rate and composition of the combustion fuel stream. The system may also include a gas turbine with an expander and having a load and a load controller in a feedback arrangement. Other embodiments include a hydrocarbon analyzer and multiple fuel streams that may be combined to form the combustion fuel stream.

A combustion system is provided for an oxy-combustion furnace. The combustion system includes at least one windbox mountable on the oxy-combustion furnace and having at least one main firing location. At least one primary inlet is positioned in the at least one main firing location for conveying fuel and the first oxidant into the oxy-combustion furnace. At least one secondary inlet is positioned in the at least one main firing location for conveying the second oxidant into the oxy-combustion furnace. The at least one secondary inlet is angularly offset from the at least one primary inlet.

A gas separation process for treating exhaust gases from combustion processes. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

A combustion apparatus comprising: a combustion chamber; a primary fuel input conduit for supplying a fuel to the combustion chamber; a secondary input conduit for supplying a combustion gas to the combustion chamber; and combustion gas supply means, wherein the combustion gas supply means is adapted to switchably supply one of air and an oxygen rich gas to at least the secondary input conduit.

A method of and control apparatus for operation of a boiler plant are described. The boiler plant has a furnace volume, an oxyfuel firing system for oxyfuel combustion of fuel in the furnace volume, and a compression system for compression of gases exhausted from the furnace volume after combustion. The method and control apparatus are characterized by the step of controlling mass flow of gases through the compression system as a means to control pressure within the furnace volume. This invention relates to both single and multi unit arrangements.