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 invention relates to a unit and method for melting in a furnace comprising a combustion-heated melting chamber, in which the air is heated by means of heat exchange with the fumes generated by combustion. The heated air is used in a gas turbine in order to generate electrical and/or mechanical energy. In addition, the effluent from the gas turbine is used to pre-heat the combustion oxygen and/or gaseous fuel upstream of the melting chamber.

Embodiments of the present invention provide a process for liquefaction of a natural gas. The process includes cooling the natural gas with a first refrigerant provided by a first cooling system and cooling the natural gas with a second refrigerant provided by a second cooling system. The second cooling system is a single phase cooling system. The first and second cooling systems operate independently from each other. The second refrigerant is cooled with the first refrigerant so that the cooling capacity of the second refrigerant and the second cooling system is increased.

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.

A method comprises receiving a carbon dioxide recycle stream having carbon dioxide and hydrocarbons. The carbon dioxide recycle stream is fed to a catalytic reactor. The hydrocarbons are converted to carbon dioxide in the catalytic reactor by a catalytic reaction without combustion to form a purified carbon dioxide recycle stream. Electrical energy is generated by using heat produced by the catalytic reactor in the conversion. Another method comprises receiving a recycle stream having carbon dioxide, C.sub.1-C.sub.2 hydrocarbons, and C.sub.3+ hydrocarbons. The C.sub.3+ hydrocarbons are separated from the carbon dioxide and the C.sub.1-C.sub.2 hydrocarbons. The carbon dioxide and the C.sub.1-C.sub.2 hydrocarbons are fed to a catalytic reactor at a pressure greater than about 300 pounds per square inch (psi), and the C.sub.1-C.sub.2 hydrocarbons are converted to carbon dioxide, water, and heat.

Disclosed is a method of retrofitting a full-scale LNG plant to enhance the LNG production capacity of the LNG plant and a method for operating such a retrofit plant. A small scale LNG plant having a capacity less than 2 MTPA can be integrated with a main LNG plant having a capacity of at least 4 MTPA such that end flash gas and boil off gas from the main LNG plant can be liquefied by the small scale LNG plant as incremental LNG. It has been found that the production capacity of the integrated system can be improved by increasing the temperature of the gas stream exiting the main cryogenic heat exchanger of the main LNG plant between 5 C. and 30 C. as compared with the design temperature.

The present application relates to a heat recovery apparatus and method. According to the heat recovery apparatus and method, low-level heat sources at a temperature less than 100 C. discharged from industrial settings or various chemical processes, for example, a petrochemicals manufacturing process are not wasted but used to generate steam and the generated steam is used for various processes to reduce an amount of consumed high-temperature steam that is an external heat source to be used for a reactor or distillation column, thereby not only maximizing energy reduction efficiency but also autonomously producing power consumed by a compressor. Also, an evaporation phenomenon of a part of a refrigerant flow which passes through the compressor may be reduced, thereby recovering heat with excellent efficiency.

The present invention provides a method and apparatus for separating air and generating electrical power. A compressed air stream produced in a main air compressor is introduced into an air separation unit that cryogenically rectifies the air into component products. During turndown conditions of the air separation unit, a combustion air stream formed from all or part of the compressed air stream is introduced into a combustor in which a fuel is combusted to produce a heated and pressurized combustion stream. Such stream is introduced to a turbine connected to an electrical generator to generate electrical power. The combustion air stream can be saturated with moisture to increase power output. Further, the combustion air stream can also be preheated with an exhaust of a gas turbine.

A LNG liquefaction plant system includes concurrent power production, wherein the refrigeration content of the refrigerant or SMR is used to liquefy and sub-cool a natural gas stream in a cold box or cryogenic exchanger. For concurrent power production, the system uses waste heat from refrigerant compression to vaporize and superheat a waste heat working fluid that in turn drives a compressor for refrigerant compression. The refrigerant may be an external SMR or an internal LNG refrigerant working fluid expanded and compressed by a twin compander arrangement.

A method and device for generating electrical energy in a combined system of power plant, cold storage system and air compression system. The air compression system has a primary air compressor for generating a primary compressed air flow at a first pressure level. The power plant has a combustion unit which operates at a second pressure level and generates a combustion gas from which electrical energy is generated. The cold storage system has means for generating cold from compressed air, means for storing cold thus produced and means for generating a compressed air flow at the second pressure level using the stored cold. In a first operating mode (charging mode), a first compressed air flow is introduced from the air compression system into the cold storage system to charge the cold reservoir. In a second operating mode (discharging mode), the first compressed air flow generated in the primary air compressor, is introduced into the cold storage system to discharge the cold reservoir and to generate a third compressed air flow at the second pressure level, which is introduced into the combustion unit. The air compression system has a first booster for boosting compressed air compressed in the primary air compressor to the second pressure level. In a third operating mode (normal mode), the entire primary compressed air flow generated in the primary air compressor is boosted in the first booster to the second compressed air level and introduced into the combustion unit.