Sinvent as

Einar Brendeng

Petter Nekså

Jostein Pettersen

Geir Skaugen

Håvard Rekstad

Gholam Reza Zakeri

Kåre Aflekt

Armin Hafner

Bengt Olav Neeraas

The present invention relates to a process plant and method for cooling and optionally liquefaction of a product gas, particularly for liquefaction of natural gas, based on a closed loop of multi-component refrigerant in heat exchange with the gas to be cooled and optionally condensed. The process plant is comprises at least one primary heat exchanger () arranged to cool the product gas directed to the heat exchanger (), at least one compressor () arranged to compress the low level refrigerant directed from the first of the at least two secondary heat exchangers (), at least one pre-cooling heat exchanger () to sub-cool and partly liquefy the compressed refrigerant, at least one phase-separator () arranged to separate the partly liquefied multi-component refrigerant into a more volatile fraction and a less volatile fraction, at least two secondary heat exchangers (), the first of the at least two secondary heat exchangers () arranged to cool the more volatile fraction from the phase-separator (), and the second of the at least two secondary heat exchangers () arranged to cool further the more volatile fraction, a throttling device () arranged to reduce the pressure of a part of the more volatile fraction to become the low level refrigerant to be heat exchanged in the second of at least two secondary heat exchangers, a throttling device () arranged to reduce the pressure of a part of the more volatile fraction to become the low level refrigerant to be heat exchanged in the at least one primary heat exchanger (), a throttling device () arranged to reducing the pressure of the less volatile fraction from the at least one phase-separator () to become part of the low level refrigerant, for mixing with the low level refrigerant from the at least one primary heat exchanger (), and the low level refrigerant from the second of at least two secondary heat exchangers () this directed to heat exchange through the first of at the least two secondary heat exchangers ().

Method for liquefaction of gas

Reversible vapor compression system including a compressor (), an interior heat exchanger (), an expansion device () and an exterior heat exchanger () connected by means of conduits in an operable relationship to form an integral main circuit. A first device is provided in the main circuit between the compressor and the interior heat exchanger, and a second device is provided on the opposite side of the main circuit between the interior and exterior heat exchangers to enable reversing of the system from cooling mode to heating mode and vice versa. The first and second device for reversing of the system include a first and second sub-circuit (A respectively B) each of which is connected with the main circuit through a flow reversing device (andrespectively). Included in the system solution is a reversible heat exchanger for refrigerant fluid, particularly carbon dioxide. It includes a number of interconnected sections arranged with air flow sequentially through the sections. The first and last sections are inter-connected whereby the refrigerant fluid flow in the heat exchanger can be changed from heating to cooling mode by means of flow changing devices provided between the respective sections.

Reversible vapor compression system

A method of defrosting of a heat exchanger (evaporator) in a vapor compression system including, downstream of a heat exchanger (evaporator) () to be defrosted, at least a compressor (), a second heat exchanger (condenser/heat rejecter) (), and an expansion device () connected by conduits in an operable manner to form an integral closed circuit. The heat exchanger () to be defrosted is subjected to essentially the same pressure as the compressor's () discharge pressure. Thus, the heat exchanger () is defrosted as the high-pressure discharge gas from the compressor () flows through to the heat exchanger, giving off heat to the heat exchanger (). In the circuit, in connection with the expansion device () a first bypass loopwith a first valve ('), is provided. A pressure reducing device (&#x2032;) is provided in a second bypass loop in conjunction with a second valve (&#x2032;&#x2033;) disposed downstream of the heat exchanger () being defrosted, whereby the first valve (&#x2032;) is open and the second valve (&#x2032;&#x2033;) is closed when defrosting takes place.

Method and arrangement for defrosting a vapor compression system

Method and process plant for liquefaction of gas, particularly natural gas with multicomponent refrigerant, suited for small and medium sized scale, where the plant solely is based on conventional two-flow plate heat exchangers and conventional oil lubricated compressors. By the arrangement of the heat exchangers and the compressors according to the invention it is avoided that oil from the compressors, that to some extend will follow the flow of refrigerant, may reach the coldest parts of the plant. Any freezing of oil and plugging of conduit etc. is thus avoided.

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Trondheim, Norway

Einar Brendeng