WO2018083747A1

WO2018083747A1 - Natural gas liquefaction facility

Info

Publication number: WO2018083747A1
Application number: PCT/JP2016/082540
Authority: WO
Inventors: 直之竹澤; 尚内海; 玄齋藤
Original assignee: 日揮株式会社
Priority date: 2016-11-02
Filing date: 2016-11-02
Publication date: 2018-05-11
Also published as: AU2016428816A1; AU2016428816B2

Abstract

[Problem] To provide a natural gas liquefaction facility having high operability and high energy efficiency. [Solution] This natural gas liquefaction facility comprises a liquefaction processing device 15 which performs processing for liquefying natural gas. An internal combustion engine 31 burns fuel gas and drives a first generator 32, a steam generation unit 33 generates steam using the combustion exhaust gas of the internal combustion engine 31, and a steam turbine 41 drives a second generator 42 using the steam generated by the steam generation unit 33. A fluid heating unit 101 heats a fluid to be heated using the steam extracted from the steam turbine 41, and a refrigerant compression unit 21 is driven by a motor 22, which consumes power generated by the first and second generators 32, 42, and compresses the refrigerant gas obtained by cooling natural gas using the liquefaction processing device.

Description

Natural gas liquefaction equipment

The present invention relates to a technology for supplying energy in a natural gas liquefaction facility.

Natural gas (NG: Natural Gas) produced in gas wells is liquefied in natural gas liquefaction equipment (NG liquefaction equipment) and then liquefied natural gas (LNG) via LNG tankers and pipelines. And shipped to the consumption area.
The NG liquefaction equipment includes various pretreatment devices that remove impurities such as moisture, liquefaction treatment devices that liquefy NG, storage tanks (LNG tanks) that store liquefied LNG, Equipment is provided.

In the liquefaction processing apparatus, NG is cooled using a refrigerant, and the refrigerant gas evaporated by heat exchange with NG undergoes a temperature drop due to compression or adiabatic expansion using a refrigerant compressor (refrigerant compression unit). , Reused for cooling NG.
The refrigerant compressor is an essential device for producing LNG, and is one of the devices that consume the most energy in the NG liquefaction facility, so that both stable operation and efficient energy supply are required. Compared to a case where a gas turbine is used as a power source for a refrigerant compressor, a motor is a power source that has excellent operability and maintainability and can operate stably for a long period of time.

For example, Non-Patent Document 1 describes the result of studying the feasibility of a large-scale LNG plant (NG liquefaction facility) with an annual output of 9 million tons using a motor-driven refrigerant compressor. In this study, a power generation system is described in which steam is generated from combustion exhaust gas of a gas turbine generator using a heat recovery steam generator, and power is generated using the steam turbine generator using the steam (FIG. .3).
However, since the power generation system described in Patent Document 1 employs a condensing steam turbine generator and discards exhaust heat to the condenser side, high thermal efficiency can be obtained by evaluating the steam turbine generator alone. On the other hand, there is room for improvement in the thermal efficiency of the entire LNG plant.

Non-Patent Document 2 describes an LNG plant that performs exhaust heat recovery with a gas turbine generator that supplies power to a motor-driven refrigerant compressor and uses the obtained hot oil as a heat source for the process. (Pp. 11-12). However, since heat recovery by hot oil is performed by sensible heat of oil, heat recovery equipment becomes large in a large LNG plant.

The present invention has been made under such a background, and an object of the present invention is to provide a natural gas liquefaction facility with high operability and energy efficiency.

The natural gas liquefaction facility of the present invention is a natural gas liquefaction facility for liquefying natural gas.
A liquefaction processing apparatus for performing processing for liquefying natural gas;
An internal combustion engine that burns fuel gas to drive the first generator;
A steam generating section for generating steam by heat exchange with combustion exhaust gas obtained by burning fuel gas in the internal combustion engine;
A steam turbine that drives the second generator using the steam generated in the steam generation unit;
A fluid heating unit that is provided in a natural gas processing apparatus that constitutes the natural gas liquefaction facility, and that heats a fluid to be heated that flows through the processing apparatus using steam extracted from the steam turbine;
A refrigerant compression unit that is driven by a motor that consumes the electric power generated by the first generator and the second generator, and that compresses the refrigerant gas that has cooled the natural gas by the liquefaction treatment device. It is characterized by that.

The natural gas liquefaction facility may have the following characteristics.
(A) The processing apparatus is an acidic gas having a gas absorption unit that removes the acidic gas contained in the natural gas by bringing the natural gas before being supplied to the liquefaction processing apparatus into contact with the gas absorption liquid. Removal device,
The fluid heating unit is provided in the acid gas removing device, and heats the gas absorbing solution sent from the gas absorbing unit to release the acid gas to regenerate the gas absorbing solution. Be part of a reboiler.
(B) The treatment device is a gas-liquid separation device including a gas-liquid separation unit that separates natural gas before being supplied to the liquefaction treatment device and liquid containing antifreeze contained in the natural gas, The fluid heating unit is a reboiler of an antifreeze liquid regeneration unit that is provided in the gas-liquid separator and heats the antifreeze sent from the gas-liquid separator to release moisture to regenerate the antifreeze.
(C) The processing apparatus is configured to concentrate liquid heavy components separated from natural gas cooled by the liquefaction processing apparatus into liquid condensate and ethane, propane, and butane, which are lighter components than condensate. And the fluid heating unit is a reboiler of the rectification unit.
(D) A moisture removing unit that brings the natural gas before being supplied to the liquefaction processing apparatus into contact with an adsorbent, and adsorbs and removes moisture contained in the natural gas to the adsorbent, and removes moisture. A regenerated gas heating unit for heating the dried natural gas extracted from the natural gas after being heated and supplying the moisture removing unit as a regenerated gas that regenerates the adsorbent after adsorbing the moisture. The dry natural gas is provided using a moisture removing device provided, and the regeneration gas heating unit is generated by the steam generation unit and is used before being supplied to the steam turbine or combustion exhaust gas of the internal combustion engine. Heating.
(E) The steam turbine is a multi-stage steam turbine in which a condenser is provided on the exhaust side of the low-pressure stage, and the fluid heating unit has steam extracted from a stage higher than the low-pressure stage. Be supplied.
(F) The internal combustion engine is a gas turbine.

According to the present invention, a refrigerant compressor is provided by an internal combustion engine that drives a first generator and a steam turbine that drives a second generator using steam generated by using combustion exhaust gas of the internal combustion engine. While supplying electric power to the motor to drive, the to-be-heated fluid which flows through the processing apparatus in a natural gas liquefaction installation is heated using the steam extracted from the said steam turbine. As a result, it is possible to stably operate the refrigerant compression unit with a motor having good operation operability and to realize a natural gas liquefaction facility with high energy efficiency.

It is a schematic diagram which shows the outline | summary of the whole structure of the natural gas liquefying installation which concerns on embodiment of this invention. It is explanatory drawing which shows the structure of the electric power generation system of the said natural gas liquefying installation.

First, a configuration example of a natural gas (NG) liquefaction facility according to an embodiment of the present invention will be described with reference to FIG.
The NG liquefaction equipment includes a gas-liquid separation device 11 that separates liquid from NG, a mercury removal device 12 that removes mercury in NG, and an acid gas removal that removes acidic gases such as carbon dioxide and hydrogen sulfide from NG. A device 13; a moisture removing device 14 for removing a trace amount of moisture contained in NG; a liquefaction processing device 15 for performing a process for liquefying NG from which these impurities have been removed; and a storage tank 16 for storing liquefied LNG. With.

The gas-liquid separator 11 separates liquid condensate at room temperature contained in NG transported by a pipeline or the like. The gas-liquid separator 11 is a gas-liquid separator (indicated as gas-liquid separator 11 in FIG. 1) composed of slender pipes, drums, etc., which are inclined to separate liquid from NG using the specific gravity difference. ) Is included. In addition, in order to prevent NG and free water from becoming a solid gas hydrate under a predetermined temperature and pressure condition and causing the pipeline to be blocked, an antifreeze is added to the NG transported by the pipeline. There is a case. As the antifreeze liquid, for example, a water absorption liquid that absorbs water, such as MEG (Monoethylene Glycol) or TEG (Triethylene Glycol), is employed.

As described above, when the NG received from the pipeline contains the antifreeze liquid, the gas-liquid separation device 11 may be further provided with the antifreeze liquid regenerating unit 111 that releases moisture contained in the antifreeze liquid.
In the gas-liquid separation unit, the antifreeze containing moisture and the condensate are further phase-separated from the liquid after the gas-liquid separation, and the antifreeze is sent to the antifreeze regenerator 111. The antifreeze liquid regeneration unit 111 is configured as a diffusion tower that heats the antifreeze liquid by the reboiler 112 to release moisture.

The mercury removing device 12 removes a trace amount of mercury contained in NG after the liquid is separated. For example, the mercury removing device 12 has a structure in which a mercury removing agent is packed in an adsorption tower, and adsorbs and removes mercury by passing NG through a packed bed of the mercury removing agent. Examples of the mercury removing agent include an activated carbon-based mercury removing agent in which sulfur is supported on activated carbon, and a metal-based mercury removing agent in which copper or zinc sulfide is supported on a carrier.

The acid gas removal device 13 makes, for example, a countercurrent contact between a gas absorbing solution containing an amine compound and a natural gas after mercury removal, such as carbon dioxide or hydrogen sulfide, which may solidify in LNG during liquefaction. An absorption tower (gas absorption part) that absorbs and removes acid gas into the gas absorption liquid is provided (indicated as acid gas removal device 13 in FIG. 1). Various gas absorption liquids containing amine compounds exist, and examples thereof include MDEA (Methyldiethanolamine) and DIPA (Di-isopropanolamine). In addition, Sulforane or the like may be used as a gas absorbing liquid other than the amine compound.

Further, the acid gas removal device 13 is provided with a regeneration tower (gas absorption liquid regeneration unit) 131 that regenerates the gas absorption liquid by discharging the acid gas from the gas absorption liquid after absorbing the acidic gas. The gas absorption liquid that has absorbed the acid gas in the absorption tower is transferred to the regeneration tower 131 and dispersedly supplied from the top of the regeneration tower 131, while the reboiler 132 provided on the bottom of the tower absorbs the gas absorption liquid in the tower. Is heated, and acid gas is released from the gas absorption liquid.

Gas containing acid gas (carbon dioxide, hydrogen sulfide, etc.) released from the gas absorbing liquid is burned, and then discharged to the atmosphere through the necessary exhaust gas treatment. On the other hand, the gas absorption liquid regenerated in the regeneration tower 131 is returned to the absorption tower of the acidic gas removal device 13 and reused for removal of acidic gas in NG.

The moisture removing device 14 is configured as an adsorption tower filled with an adsorbent that adsorbs and removes moisture in NG, such as molecular sieve and silica gel. The moisture removing apparatus 14 of this example includes a plurality of adsorption towers, and the NG after the acid gas is removed is switched and supplied to any of the adsorption towers. The adsorption tower to which NG is supplied functions as a moisture removal unit that adsorbs and removes moisture contained in the NG by passing NG through the packed bed of adsorbent (in FIG. 1, the moisture removal device 14 Is displayed).

The adsorption tower to which NG is not supplied releases the moisture adsorbed by the adsorbent and waits until the supply destination of NG is switched after the regeneration process for regenerating the adsorbent is performed (in FIG. 1, Adsorbent regeneration tower 141).
In regeneration of the adsorbent, the moisture removing device 14 of this example uses NG (dry NG) after moisture is removed. The dried NG is heated to, for example, about 280 to 300 ° C. by the regeneration gas heating unit 142 and then supplied to the adsorbent regeneration tower 141 as a regeneration gas for the adsorbent. The supply destination of the regeneration gas can also be switched between a plurality of adsorption towers.

When a high-temperature regeneration gas is supplied to the adsorbent regeneration tower 141, moisture adsorbed on the adsorbent is released to the regeneration gas side, and the adsorbent can be regenerated. The regeneration gas (NG) containing moisture used for regeneration of the adsorbent is discharged from the adsorbent regeneration tower 141, cooled, gas-liquid separated, and then used as fuel gas consumed in the NG liquefaction facility Is done.

NG after impurities are removed by the various pretreatment apparatuses described above is supplied to the liquefaction treatment apparatus 15 and liquefied. The liquefaction processing device 15 includes a precooling heat exchanger that precools NG with a precooling refrigerant mainly composed of propane, a scrub column that removes heavy components from the precooled NG, nitrogen, methane, ethane, propane, and the like. A cryogenic heat exchanger (MCHE: Main Cryogenic Heat Exchanger) that cools and liquefies NG with a mixed refrigerant (Mixed Refrigerant) containing multiple types of refrigerant raw materials, precooling refrigerant and mixed refrigerant evaporated by heat exchange The apparatus includes a refrigerant compressor (refrigerant compression unit) 21 that compresses gas and an aftercooler that cools the compressed refrigerant. In FIG. 1, individual refrigerant compressors for precooling refrigerant and mixed refrigerant (low pressure MR compressor 21a for mixed refrigerant, high pressure MR compressor 21b, C3 compressor 21c for precooling refrigerant) are combined into one. In addition to those described above, the individual description of each device described above is omitted.

Further, the liquefaction apparatus 15 includes a deethanizer for separating ethane from the liquid separated from the cooled NG (liquid heavy component), a depropanizer for separating propane from the liquid after ethane separation, and a liquid after the propane separation. A rectifying unit 151 including a debutizer that separates butane and obtains liquid condensate at room temperature is provided. Each of the deethanizer, the depropanizer, and the debutizer is configured as a rectifying column that heats a liquid by a reboiler 152 (a plurality of reboilers 152 are collectively shown in FIG. 1) and rectifies each component. .

The liquefied natural gas (LNG) that has been liquefied and supercooled by the liquefaction processing device 15 is sent to the storage tank 16 and stored therein. The LNG stored in the storage tank 16 is fed by an LNG pump (not shown) and shipped to an LNG tanker or pipeline.

In the NG liquefaction facility having the above-described configuration, the refrigerant compressor 21 (low pressure MR compressor 21a, high pressure MR compressor 21b, C3 compressor 21c) is an indispensable device for the production of LNG, and in the NG liquefaction facility. It is one of the devices with the highest energy consumption. The NG liquefaction facility of this example employs a motor 22 that is excellent in driving operability and maintainability and can operate stably for a long period of time as a power source for driving these refrigerant compressors 21.
Further, the NG liquefaction facility of this example includes a power generation system for supplying power to power consuming equipment such as the motor 22 of the refrigerant compressor 21. Hereinafter, the configuration of the power generation system will be described with reference to FIG. Will be described.

As shown in FIG. 2, the power generation system of this example includes a plurality of, for example, five gas turbines 31 that are internal combustion engines for driving a generator (first generator) 32 to generate power. ing. The gas turbine 31 drives the generator 32 with power obtained by burning fuel gas including boil off gas (BOG) generated in the storage tank 16.
Since this power generation system includes a plurality of gas turbines 31, the output of the remaining gas turbines 31 can be output even when one of the gas turbines 31 stops due to regular maintenance or trouble. By increasing, the decrease in the output of the stopped gas turbine 31 can be compensated.

Each gas turbine 31 is provided with a steam generator 33 that generates steam by heat exchange with the combustion exhaust gas discharged from the gas turbine 31. In the steam generation section 33, for example, a relatively high temperature and high pressure steam having a temperature in the range of 385 to 523 ° C. and a pressure in the range of 40 to 96 Barg is obtained. The steam generated in each steam generation unit 33 is collected in a common high-pressure steam header 47.
In FIG. 1, for convenience of illustration, as shown in FIG. 2, a set of a plurality of gas turbines 31, generators 32, and steam generators 33 provided as a set is collectively displayed.

Furthermore, the power generation system of this example uses a plurality of units, for example, four steam turbines, for generating power by driving the generator (second generator) 42 using the steam generated by the steam generation unit 33. 41 is configured as a combined cycle system. Each steam turbine 41 is configured in multiple stages, and a surface condenser 43 is provided on the outlet side of the lowest-pressure side low-pressure stage (condensation type). Here, a plurality of steam turbines 41 are provided, and the decrease in the output of the stopped steam turbine 41 can be compensated for in periodic maintenance, troubles, etc., as in the case of the gas turbine 31.
Further, the boiler water condensed by the surface condenser 43 is collected in the boiler water treatment unit 51, and after the addition of a canning agent or the like, the boiler water is supplied again to the steam generation unit 33.

The

generators

32 and 42 driven by the gas turbines 31 and the steam turbine 41 generate electric power having a voltage of, for example, 33 kV, and the electric power is boosted to, for example, 110 kV at the substation 61. The electric power boosted at the substation 61 is supplied to the motor 22 for driving the refrigerant compressor 21 via a variable drive unit (VSD: Variable Speed Drive) 62. The NG liquefaction facility provided with the refrigerant compressor 21 driven by the electric motor 22 is referred to as “e-LNG”.
Electric power is also supplied to other power consuming devices in the NG liquefaction facility.

In the power generation system having the above-described configuration, the multi-stage steam turbine 41 that obtains power by using the steam obtained from the steam generation unit 33 is intermediate in the high pressure side than the low pressure stage to which the surface condenser 43 is connected. A cogeneration system is configured to extract steam from the stage and use the steam as a heat source of the fluid heating unit 101 of the processing apparatus 100 provided in the NG liquefaction facility.

From each steam turbine 41, for example, a temperature within a range of 147 to 170 ° C. and a pressure within a range of 4.5 to 8 Barg, which is lower in temperature and pressure than the steam generated in the steam generation unit 33, is extracted. The Steam extracted from each steam turbine 41 is collected into a common steam supply header 46.

As the fluid heating unit 101 of the processing apparatus 100 that supplies steam from the steam supply header 46, the reboiler 112 of the antifreeze regenerator 111, the reboiler 132 of the gas absorption liquid regenerator 131, and the rectifier (deethanizer, depropanizer, Each reboiler 152 of a debutizer 151) is mentioned.

As shown in FIG. 1, at the outlet side of each

reboiler

112, 132, 152, heated fluid thermometers 113, 133 that measure the temperature of the heated fluid (antifreeze liquid, gas absorption liquid, liquid separated from NG). , 153 are provided. Then, the amount of steam supplied from the steam supply header 46 to each

reboiler

112, 132, 152 is adjusted by the flow

rate adjusting valves

134, 144, 154 so that the temperature of each heated fluid approaches a preset target value. Is done.
Boiler water condensed in each

reboiler

112, 132, 152 is collected in the boiler water treatment unit 51.

On the other hand, the regeneration gas heating unit 142 used for regeneration of the adsorbent in the adsorbent regeneration tower 141 needs to heat the regeneration gas to a high temperature of about 280 to 300 ° C. as described above. In this regard, as described above, it is difficult for the steam supplied from the steam supply header 46 having a temperature of about 147 to 170 ° C. to heat the regeneration gas to a temperature necessary for regeneration of the adsorbent.

Therefore, the high-temperature steam extracted from the high-pressure steam header 47 is supplied to the regeneration gas heating unit 142 and used for heating the regeneration gas.
As shown in FIG. 1, a gas thermometer 143 that measures the temperature of the dry gas is provided on the outlet side of the regeneration gas heating unit 142. Then, supply of steam to the regeneration gas heating unit 142 is performed by a flow rate control valve 144 provided in a line for extracting high-temperature steam from the high-pressure steam header 47 so that the temperature of the dry gas approaches a preset target value. The amount is adjusted. The boiler water condensed in each regeneration gas heating unit 142 is collected in the boiler water treatment unit 51.
In addition, as a heat source for heating the dry gas in the regeneration gas heating unit 142, an exhaust heat recovery facility for recovering exhaust heat of the gas turbine 31 is provided, and drying is performed by heat exchange with the combustion exhaust gas discharged from the gas turbine 31. The gas may be heated.

In the above-described power generation system, the fluid heating unit 101 (boiler 112) of the processing device 100 (the antifreeze regenerator 111 of the gas-liquid separator 11; , 132, 152), an amount of steam commensurate with the amount of heat required to heat the fluid to be heated (antifreeze liquid, gas absorption liquid, liquid separated from NG) is supplied to the steam supply header 46 via the steam turbine 41. Supplied. However, the amount of heat required in the fluid heating unit 101 varies depending on the amount of NG processing, the nature of NG, and the like.

Therefore, the power generation system secures the supply of steam commensurate with the heat consumption on the fluid heating unit 101 side by maintaining the pressure of the steam supply header 46 at the target pressure. Therefore, the steam supply header 46 is provided with a pressure gauge 45, and provided in the extraction line of each steam turbine 41 so that the pressure of the steam supply header 46 measured by the pressure gauge 45 becomes a preset target pressure. The opening degree of the extracted bleed valve 44 is adjusted.

When the pressure of the common steam supply header 46 is controlled by adjusting the opening of the extraction valves 44 provided in the plurality of steam turbines 41, for example, the opening and closing are performed so that all the extraction valves 44 have the same opening. May be.
In addition, when the priority order for adjusting the opening degree of the extraction valve 44 among the plurality of steam turbines 41 is determined and the consumption of steam on the processing apparatus 100 side increases, the extraction of the steam turbine 41 with higher priority is performed. When the valve 44 is opened and the opening degree of the extraction valve 44 reaches the upper limit, the opening degree of the steam turbine 41 of the next priority may be adjusted to be increased. As a priority setting criterion, the priority order of the extraction valve 44 provided in the steam turbine 41 is such that the rate of decrease in thermal efficiency due to the increase in the amount of extraction is small, for example, the output is larger than that of the other steam turbines 41. An example of setting to be high can be given.

Using the extraction valves 44 provided in the plurality of steam turbines 41, the pressure adjustment of the steam supply header 46 based on a preset rule is performed by, for example, the control unit 7 including a computer system that performs overall control of the entire NG liquefaction facility. It is done using.

Furthermore, in the power generation system of this example, in order to balance the difference between the supply amount of steam supplied from the steam generation unit 33 and the consumption amount of steam on the steam turbine 41 side, for example, a steam boiler 52 that uses fuel gas. Is provided. The steam boiler 52 increases or decreases the supply amount of steam from each steam boiler 52 so that the pressure of the high-temperature high-pressure steam measured by a pressure gauge (not shown) provided in the high-pressure steam header 47 becomes a target pressure in advance. .

The operation of the power generation system of the NG liquefaction facility having the configuration described above will be described.
First, in the power generation system, the

generators

32 and 42 are driven by the gas turbines 31 and the steam turbines 41, and a necessary amount of power is supplied to each power consuming device in the NG liquefaction facility including each refrigerant compressor 21. It shall be. Further, with respect to the fluid heating unit 101 of the processing apparatus 100, the balance is such that steam of the amount of heat necessary for heating the fluid to be heated is supplied to the steam supply header 46 by extraction from the steam turbine 41. To do. Furthermore, it is assumed that a certain amount of high-temperature steam is supplied to the regeneration gas heating unit 142, and fluctuations in the supply amount do not restrict steam consumption and supply balance of the entire power generation system.

At this time, the steam consumption in the fluid heating unit 101 increases and the pressure in the steam supply header 46 decreases due to an increase in the amount of NG treatment on the processing apparatus 100 side or a change in the properties of NG. Let us consider the case where the supply / consumption balance changes.
In this case, based on a preset rule, the opening degree of the extraction valve 44 provided in the extraction line of the predetermined steam turbine 41 is increased to increase the amount of steam extracted to the steam supply header 46 side, Adjustment is performed so that the pressure of the steam supply header 46 is maintained at the target pressure.

In the steam turbine 41, when extraction is performed from an intermediate stage on the higher pressure side than the low pressure stage to which the surface condenser 43 is connected, the amount of steam discharged to the surface condenser 43 side is reduced. As a result, the power generation efficiency of each steam turbine 41 decreases, and the power generation amount of the generator 42 decreases.

At this time, if there is no change in the power consumption in the NG liquefaction facility, it is necessary to compensate for the decrease in the power generation amount in the generator 42.
Therefore, for example, when there is a margin in the output of the gas turbine 31, the decrease in the amount of power generated in the generator 42 can be compensated on the generator 32 side by increasing the output of the gas turbine 31. In this adjustment method, since the amount of steam generated in the steam generating section 33 increases, the amount of steam supplied from the steam boiler 52 is decreased to achieve a balance.

When there is a surplus in the cooling capacity on the surface condenser 43 side, the supply amount of cooling water to the surface condenser 43 is increased, and the supply amount of steam from the high-pressure steam header 47 to the steam turbine 41 is increased. By increasing the output of the steam turbine 41, the amount of power generated by the generator 42 can be restored. In this adjustment method, the increase in the amount of steam consumed in the steam turbine 41 is balanced by increasing the amount of steam supplied from the steam boiler 52.

In the above-described two adjustment methods, when the output of the gas turbine 31 is increased, the fuel consumption in these gas turbines 31 is increased, and when the output of the steam turbine 41 is increased, the fuel consumption in the steam boiler 52 is increased. As long as it does not violate the restrictions on the facility side, it is recommended to adopt an adjustment method with less fuel consumption per unit power generation.

Next, due to reasons such as a decrease in the amount of NG processing on the processing apparatus 100 side and a change in the properties of NG, the steam consumption in the fluid heating unit 101 decreases, and the steam in the direction in which the pressure of the steam supply header 46 increases Let us consider the case where the supply / consumption balance changes.
In this case, based on a preset rule, the opening degree of the extraction valve 44 provided in the extraction line of the predetermined steam turbine 41 is reduced to reduce the amount of steam extracted to the steam supply header 46 side, Adjustment is performed so that the pressure of the steam supply header 46 is maintained at the target pressure.

As a result, in the steam turbine 41, the amount of steam discharged toward the surface condenser 43 is increased, the power generation efficiency of each steam turbine 41 is improved, and the power generation amount of the generator 42 is increased.
At this time, if there is no change in the power consumption amount in the NG liquefaction facility, it is necessary to reduce the increase in the power generation amount in the generator 42.

For example, when the actual output has a margin with respect to the output lower limit value of the gas turbine 31, the increase in the amount of power generation in the generator 42 is balanced on the generator 32 side by decreasing the output of the gas turbine 31. Can be made. In this adjustment method, since the amount of steam generated in the steam generating section 33 decreases, the amount of steam supplied from the steam boiler 52 is increased to achieve a balance.

Further, when there is a margin with respect to the lower limit value of the steam discharge amount to the surface condenser 43 side, the supply amount of the cooling water to the surface condenser 43 is reduced and the high pressure steam header 47 to the steam turbine 41 is reduced. The power generation amount of the generator 42 can be restored by reducing the steam supply amount and decreasing the output of the steam turbine 41. In this adjustment method, the decrease in the steam consumption in the steam turbine 41 is balanced by reducing the amount of steam supplied from the steam boiler 52.

In the above-described two adjustment methods, when the output of the gas turbine 31 is reduced, the fuel consumption in the gas turbine 31 is reduced, and when the output of the steam turbine 41 is reduced, the fuel consumption in the steam boiler 52 is reduced. As long as it does not violate the restrictions on the facility side, it is advisable to adopt an adjustment method with a large reduction in fuel consumption per unit power generation.

The NG liquefaction facility according to the present embodiment has the following effects. A motor 22 that drives the refrigerant compressor 21 includes a gas turbine 31 that drives the generator 32 and a steam turbine 41 that drives the generator 42 using steam generated by using the combustion exhaust gas of the gas turbine 31. The heated fluid flowing through the processing apparatus 100 in the NG gas liquefaction facility is heated using the steam extracted from the steam turbine 41. As a result, the refrigerant compressor 21 can be stably operated by the motor 22 having good operability, and an NG liquefaction facility with high energy efficiency can be realized.

For example, when NG liquefaction equipment (4.5 million tons per year) having the configuration shown in FIGS. 1 and 2 is simulated, the gas turbine 31 is driven and consumed in response to steam generation in the steam generation unit 33 and steam boiler 52. The total fuel gas consumption was 749 MW. On the other hand, the total amount of power generated by the

generators

32 and 42 and the amount of steam supplied to the fluid heating unit 101 and the regeneration gas heating unit 142 was 463 MW. Therefore, the overall thermal efficiency of the NG liquefaction facility is 62%. This can be said to be able to realize a very high thermal efficiency compared with the thermal efficiency (approximately 25-35%) of a general NG liquefaction facility in which the refrigerant compressor 21 is driven by a gas turbine.

Here, the internal combustion engine for driving the generator 32 is not limited to the gas turbine 31. For example, the generator 32 may be driven using a gas engine, and the steam turbine 41 that drives the generator 42 may be driven using steam obtained by heat exchange with the combustion exhaust gas of the gas engine. . In a relatively small NG liquefaction facility, the refrigerant compressor 21 can supply necessary power even for a gas engine having a smaller output than the gas turbine 31.

Further, the steam turbine 41 that drives the second generator 42 is not limited to the condensate type. For example, a part or all of the steam turbine 41 provided in the power generation system shown in FIGS. The amount of change in the power generation amount of the generator 42 accompanying the increase or decrease in the amount of steam supplied from the back pressure steam turbine 41 to the steam supply header 46 can be adjusted by the increase or decrease in the amount of steam discharged to the surface capacitor 43 side. Can not. For this reason, the change in the power generation amount is balanced by decreasing or increasing the output of the gas turbine 31.
In addition to this, in the case where a necessary amount of steam cannot be extracted from the steam turbine 41 due to equipment restrictions such as one steam turbine 41 being stopped, as shown in FIG. 47 and the steam supply header 46 are normally closed (denoted as “S” in FIG. 1), and a pressure reducing valve 481 for reducing the pressure of the steam when the bleed is performed, and the temperature of the extracted steam is lowered. A bleed line 48 provided with a desuperheater 482 may be provided.

Furthermore, the NG liquefaction equipment to which the power generation system of this example is applied may not include all the pretreatment devices shown in FIG. For example, when the antifreeze liquid is not added to the NG received from the pipeline, the installation of the antifreeze liquid regeneration unit 111 may be omitted. Further, when the amount of acid gas contained in NG is large, the acid gas may be removed by membrane separation instead of the acid gas removing device 13 using an amine compound or the like. In the case of membrane separation, the acid gas removing device 13 is not provided with the regeneration tower 131.

DESCRIPTION OF SYMBOLS 100 Processing apparatus 101 Fluid heating part 11 Gas-liquid separation apparatus (gas-liquid separation part)
12 Mercury removal device 13 Acid gas removal device (gas absorption part)
14 Moisture removal device (moisture removal unit)
DESCRIPTION OF SYMBOLS 15 Liquefaction processing apparatus 16 Storage tank 21 Refrigerant compressor 22 Motor 31 Gas turbine 32 Generator 33 Steam generation part 41 Steam turbine 42 Generator 7 Control part

Claims

In natural gas liquefaction facilities that liquefy natural gas,
A liquefaction processing apparatus for performing processing for liquefying natural gas;
An internal combustion engine that burns fuel gas to drive the first generator;
A steam generating section for generating steam by heat exchange with combustion exhaust gas obtained by burning fuel gas in the internal combustion engine;
A steam turbine that drives the second generator using the steam generated in the steam generation unit;
A fluid heating unit that is provided in a natural gas processing apparatus that constitutes the natural gas liquefaction facility, and that heats a fluid to be heated that flows through the processing apparatus using steam extracted from the steam turbine;
A refrigerant compression unit that is driven by a motor that consumes the electric power generated by the first generator and the second generator, and that compresses the refrigerant gas that has cooled the natural gas by the liquefaction treatment device. Natural gas liquefaction equipment characterized by that.
The treatment device is an acid gas removal device including a gas absorption unit that removes the acid gas contained in the natural gas by bringing the natural gas before being supplied to the liquefaction treatment device into contact with the gas absorption liquid. Yes,
The fluid heating unit is provided in the acid gas removing device, and heats the gas absorbing solution sent from the gas absorbing unit to release the acid gas to regenerate the gas absorbing solution. The natural gas liquefying apparatus according to claim 1, wherein the natural gas liquefying apparatus is a reboiler.
The processing device is a gas-liquid separation device including a gas-liquid separation unit that separates natural gas before being supplied to the liquefaction processing device and liquid containing antifreeze contained in the natural gas,
The fluid heating unit is provided in the gas-liquid separator, and is a reboiler of an antifreeze liquid regeneration unit for regenerating the antifreeze liquid by heating the antifreeze liquid sent from the gas-liquid separation unit to release moisture. The natural gas liquefying apparatus according to claim 1, wherein
The treatment device is a rectifier that rectifies the liquid heavy fraction separated from the natural gas cooled by the liquefaction treatment device into liquid condensate and ethane, propane, and butane that are lighter components than the condensate. Torube,
The natural gas liquefying apparatus according to claim 1, wherein the fluid heating unit is a reboiler of the rectification unit.
A natural gas before being supplied to the liquefaction processing apparatus and an adsorbent are brought into contact with each other, and a moisture removing unit that adsorbs and removes moisture contained in the natural gas by the adsorbent, and after moisture is removed. A regeneration gas heating unit for heating the dried natural gas extracted from the natural gas and supplying the moisture removal unit as a regeneration gas for regenerating the adsorbent after adsorbing the moisture. Equipped with a water removal device,
The regeneration gas heating unit heats the dry natural gas using steam generated by the steam generation unit and supplied to the steam turbine or combustion exhaust gas of the internal combustion engine. Item 4. A natural gas liquefying apparatus according to Item 1.
The steam turbine is a multi-stage steam turbine in which a condenser is provided on the exhaust side of the low-pressure stage, and steam extracted from a stage higher in pressure than the low-pressure stage is supplied to the fluid heating unit. The natural gas liquefying apparatus according to claim 1.
The natural gas liquefaction facility according to claim 1, wherein the internal combustion engine is a gas turbine.