A ship comprising an engine is disclosed. The ship comprising an engine comprises: a self-heat exchanger which heat-exchanges boil-off gas discharged from a storage tank; a multi-stage compressor which compresses, in multi-stages, boil-off gas that passed through the self-heat exchanger after being discharged from the storage tank; a first decompressing device which expands one portion of boil-off gas that passed through the self-heat exchanger after being compressed by the multi-stage compressor; and a second decompressing device which expands the other portion of the boil-off gas that passed through the self-heat exchanger after being compressed by the multi-stage compressor, wherein the self-heat exchanger uses boil-off gas discharged from the storage tank and boil-off gas expanded by the first decompressing device as refrigerants for cooling boil-off gas compressed by the multi-stage compressor.

A proposed method for thermally assisted electric energy storage is characterized by a significant increase in round-trip efficiency through a profitable use of waste heat energy streams from the co-located power generation and industrial facilities, combustion of renewable or fossil fuels, or harnessing the renewable energy sources. In the charge operation mode it is achieved by superheating and expansion of recirculating air stream in the liquid air energy storage with self-producing a part of power required for air liquefaction. In the discharge operation mode it is attained through the repeated and efficient use of a stream of discharged air in auxiliary power production cycle.

A process for liquefying methane-rich gases comprising providing a stream of feed methane-rich gas at a pressure of from 40 bar to 120 bar and containing higher hydrocarbons; providing a stream of methane-rich recycle gas at a pressure of from 40 bar to 120 bar; mixing the feed gas with a first part of the recycle gas; passing the resulting mixture to a gas expander, the expander outlet having a pressure of between 3 bar and 50 bar, so as to form a mixture of vapor and a condensed liquid containing higher hydrocarbons; separating the expander outlet stream into a liquid stream and a vapor stream; reheating and compressing said vapor stream to a pressure of from 40 bar to 120 bar to form a first constituent of the above-said recycle gas; cooling a second part of the said recycle gas to a temperature higher than the outlet temperature of the said expander; passing said cooled second part of the recycle gas into a liquefaction unit to form liquefied methane and a second vapor stream; reheating and compressing said second vapor stream to a pressure of from 40 bar to 120 bar to form a second constituent of the above-said recycle gas.

A method for producing liquid natural gas (LNG) includes the following steps. Compressor stations forming part of existing natural-gas distribution network are identified. Compressor stations that are geographically suited for localized distribution of LNG are selected. Natural gas flowing through the selected compressor stations is diverted to provide a high pressure first natural gas stream and a high pressure second natural gas stream. A pressure of the first natural gas stream is lowered to produce cold temperatures through pressure let-down gas expansion and then the first natural gas stream is consumed as a fuel gas for an engine driving a compressor at the compressor station. The second natural gas stream is first cooled with the cold temperatures generated by the first natural gas stream, and then expanded to a lower pressure, thus producing LNG.

A ship includes: a boil-off gas heat exchanger installed on a downstream of a storage tank and heat-exchanges a compressed boil-off gas (a first fluid) by a boil-off gas discharged from the storage tank as a refrigerant, to cool the boil-off gas; a compressor installed on a downstream of the boil-off gas heat exchanger and compresses a part of the boil-off gas discharged from the storage tank; an extra compressor installed on a downstream of the boil-off gas heat exchanger and in parallel with the compressor and compresses the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid which is cooled by the boil-off gas heat exchanger; and a refrigerant decompressing device which expands a second fluid, which is sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship including a liquefied gas storage tank includes: first and second compressors which compresse a boil-off gas discharged from a storage tank; a boost compressor which compresses one part of the boil-off gas that is compressed by at least any one of the first compressor and/or the second compressor; a first heat exchanger which heat exchanges the boil-off gas compressed by the boost compressor and the boil-off gas discharged from the storage tank; a refrigerant decompressing device which expands the other part of the boil-off gas that is compressed by at least any one of the first compressor and/or the second compressor; a second heat exchanger which cools, by a fluid expanded by the refrigerant decompressing device as a refrigerant; and an additional compressor which is compresses the refrigerant that passes through the refrigerant decompressing device and second heat exchanger.

A ship includes: a boil-off gas heat exchanger which is installed on a downstream of a storage tank and heat-exchanges a compressed boil-off gas (a first fluid) by a boil-off gas discharged from the storage tank as a refrigerant to cool the boil-off gas; a compressor installed on a downstream of the boil-off gas heat exchanger and compresses a part of the boil-off gas from the storage tank; an extra compressor which is installed on a downstream of the boil-off gas heat exchanger and in parallel with the compressor and compresses the other part of the boil-off gas from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid; and a refrigerant decompressing device which expands a second fluid, which is sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship includes: a boil-off gas heat exchanger which heat-exchanges a compressed boil-off gas (a first fluid) by means of a boil-off gas discharged from the storage tank as a refrigerant; a compressor installed on the downstream of the boil-off gas heat exchanger and compressing a part of the boil-off gas discharged from the storage tank; first and second extra compressors provided in parallel with the compressor on the downstream of the boil-off gas heat exchanger and compressing the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid cooled by means of the boil-off gas heat exchanger; a refrigerant decompressing device which expands a second fluid, which has been sent to the refrigerant heat exchanger and cooled by means of the refrigerant heat exchanger, and then sending the expanded second fluid back to the refrigerant heat exchanger.

A ship including a storage tank for storing a liquefied gas includes: a boil-off gas (BOG) heat exchanger installed on a downstream of a storage tank and heat-exchanges a compressed BOG (a first fluid) by a BOG discharged from the storage tank as a refrigerant, to cool the BOG; a compressor installed on a downstream of the BOG heat exchanger and compresses a part of the BOG discharged from the storage tank; an extra compressor installed on a downstream of the BOG heat exchanger and in parallel with the compressor and compresses the other part of the BOG discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid cooled by the BOG heat exchanger; and a refrigerant decompressing device which expands a second fluid sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship includes: an boil-off gas heat exchanger installed on a downstream of the storage tank such that compressed boil-off gas (first fluid) is made to exchange heat and cooled using boil-off gas discharged from the storage tank as a refrigerant; a compressor installed on a downstream of the boil-off gas heat exchanger so as to compress a part of the boil-off gas discharged from the storage tank; an extra compressor installed on a downstream of the boil-off gas heat exchanger in parallel with the compressor so as to compress the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger for additionally cooling the first fluid that is cooled by the boil-off gas heat exchanger; and a refrigerant decompressing device which expands the second fluid sent to the refrigerant heat exchanger and cooled by the refrigerant heat exchanger.