JP2016176654A - Raw material gas liquefaction device and raw material gas liquefaction amount correction control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a raw material gas liquefaction device having a feed line of liquefied raw material gas, which enables stable liquefaction operation of raw material gas compared to conventional ones, and provide a control method for correcting a liquefaction amount of raw material gas.SOLUTION: A raw material gas liquefaction device has a feed line 110 configured to supply raw material gas, and a refrigerant circulation line 130 configured to circulate refrigerant for cooling raw material gas. In the raw material gas, a cold generation system 141 in the refrigerant circulation line has an expansion turbine 138 configured to circulate refrigerant in a gas state, and generates cold. The raw material gas liquefaction device has a control device 150 configured to control a liquefaction amount of raw material gas according to the outlet side refrigerant temperature of the expansion turbine.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a raw material gas liquefying apparatus for liquefying a raw material gas such as hydrogen gas that is liquefied at an extremely low temperature by using cold heat generated in a refrigerant circulation line, and a method for controlling the liquefaction amount correction of the raw material gas.

For example, as a system for liquefying a raw material gas such as hydrogen gas, for example, Patent Document 1 discloses a feed line for supplying raw material hydrogen gas and a refrigerant circulation line (recycling line) for circulating a refrigerant for cooling the raw material hydrogen gas. And a liquefaction system for liquefying hydrogen gas by heat exchange using a heat exchanger. Here, the feed line is provided with a feed compressor for increasing the pressure of the raw material hydrogen gas, while the refrigerant circulation line is provided with an expansion turbine for adiabatic expansion of the refrigerant, and a low-pressure compressor and a high-pressure compressor for compressing the refrigerant. And are provided.
As a method for controlling the liquefaction of hydrogen gas in the liquefaction system configured as described above, Patent Document 1 discloses the operation of a feed compressor, a low-pressure and a high-pressure compressor, and an expansion turbine based on the set value of the liquefaction amount of hydrogen gas. It is disclosed that it is possible to cope with the change of the load of the liquefier by changing the load (refrigerant amount) of the refrigerant circulation line.

Patent Document 2 discloses an operation control method and apparatus for a liquefaction refrigeration apparatus including a helium liquefaction refrigeration apparatus.
Furthermore, Patent Document 3 discloses a helium liquefaction and refrigeration apparatus operation control method capable of maintaining a stable operation state without causing excessive or insufficient refrigeration output even when there is a sudden change in heat load in a cryogenic environment section. Is disclosed.

JP 2012-219711 A JP-A-6-265230 Japanese Patent Laid-Open No. 61-268972

  In the liquefaction system described in the above-mentioned Patent Document 1, it is difficult to obtain a desired liquefaction amount from the raw material hydrogen gas due to a decrease in the flow rate of the refrigerant accompanying aging deterioration in the heat exchanger, expansion turbine, and compressor included in the system. There is a possibility that. Further, the liquefaction system does not cope with the fluctuation of the supply amount of the raw material hydrogen gas from the upstream of the liquefaction system. Therefore, when the supply amount of the raw material hydrogen gas varies, there is a possibility that the heat balance in the liquefaction system is lost due to insufficient cooling or overcooling of the raw material hydrogen gas, and stable liquefaction operation cannot be performed.

  Moreover, in the above-mentioned Patent Document 2, the opening adjustment of the inlet valve of the expansion turbine is performed according to the inlet pressure of the low-pressure expansion turbine as a method for efficiently operating the expansion turbine for generating cold regardless of the fluctuation of the refrigeration load. However, it is stated that the bypass valve opening of the return line is adjusted according to the inlet temperatures of the high-pressure expansion turbine and the low-pressure expansion turbine. However, the liquefaction refrigeration apparatus disclosed in Patent Document 2 corresponds only to the refrigerant circulation line disclosed in Patent Document 1, and does not have a feed line for source gas. Therefore, when it has a feed line, even in the liquefaction refrigeration apparatus disclosed in Patent Document 2, it is considered that stable liquefaction operation cannot be performed.

  Moreover, in the above-mentioned Patent Document 3, the flow rate of the expansion turbine is calculated from the fluctuation of the liquid level or pressure in the He storage tank section as a method for maintaining a stable operation state even when a sudden thermal load fluctuation occurs in the He storage tank section. The Joule-Thomson valve (hereinafter referred to as the JT valve) is adjusted by adjusting the flow rate, and further correcting the flow rate according to the temperature at the junction of the turbine line and the refrigerant return line. To adjust. However, similarly to Patent Document 2 described above, Patent Document 3 does not have a feed line for source gas, and it is considered that a stable liquefaction operation cannot be performed when a feed line is provided.

  The present invention was made to solve the above-described problems, and in a raw material gas liquefying apparatus having a liquefied raw material gas feed line, a stable liquefying operation of the raw material gas is possible as compared with the conventional case. It is an object of the present invention to provide a source gas liquefying apparatus and a source gas liquefaction amount correction control method.

In order to achieve the above object, the present invention is configured as follows.
That is, the raw material gas liquefying apparatus according to the first aspect of the present invention includes a feed line that supplies a raw material gas whose boiling point is lower than that of nitrogen gas, and a refrigerant circulation line that circulates a refrigerant for cooling the raw material gas. In a raw material gas liquefying apparatus for liquefying the raw material gas,
The refrigerant circulation line includes a cold heat generation system, the cold heat generation system is transferred in a gas state without liquefying the refrigerant, has an expansion turbine for expanding the refrigerant, and generates cold.
A control device for controlling the amount of liquefaction of the raw material gas according to the outlet side refrigerant temperature of the expansion turbine is provided.

Further, the raw material gas liquefaction amount correction control method according to the second aspect of the present invention circulates a feed line for supplying a raw material gas for liquefaction whose boiling point is lower than that of nitrogen gas, and a refrigerant for cooling the raw material gas. In the raw material gas liquefaction amount correction control method, which is executed by the raw material gas liquefier having the refrigerant circulation line and the control device,
The refrigerant circulation line includes a cold heat generation system, the cold heat generation system is transferred in a gas state without liquefying the refrigerant, has an expansion turbine for expanding the refrigerant, and generates cold.
The control device corrects and controls the liquefaction amount of the source gas in accordance with the outlet side refrigerant temperature of the expansion turbine.

  According to the raw material gas liquefaction apparatus of the first aspect and the raw material gas liquefaction amount correction control method of the second aspect, control for controlling the liquefaction amount of the raw material gas in accordance with the outlet side refrigerant temperature of the expansion turbine in the refrigerant circulation line. By providing the apparatus, it is possible to adjust the refrigerant temperature and the liquefaction amount of the source gas. As a result, regardless of the flow rate decrease due to aging in the heat exchanger, expansion turbine, and compressor provided in the raw material gas liquefaction device, or the fluctuation in the supply amount of the raw material gas supplied from the upstream of the raw material gas liquefaction device The amount of gas liquefaction can be automatically corrected, and there is no lack of cooling or overcooling of the raw material gas, and stable production of the liquefied raw material gas can be realized as compared with the conventional case.

  According to the raw material gas liquefying apparatus in the first aspect of the present invention and the raw material gas liquefying method in the second aspect, the liquefying operation of the raw material gas can be performed more stably than in the past.

It is a figure which shows schematic structure of the raw material gas liquefying apparatus of a 1st aspect. It is a block diagram explaining operation | movement of the liquefaction amount correction | amendment control method performed with the raw material gas liquefying apparatus shown in FIG. It is a block diagram explaining the opening degree correction | amendment calculation operation | movement of the feed type | system | group JT valve shown in FIG. It is a figure explaining (DELTA) load factor calculation operation | movement shown in FIG.

  A raw material gas liquefying apparatus as an embodiment and a raw material gas liquefaction amount correction control method executed by the raw material gas liquefying apparatus will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals. In addition, in order to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art, a detailed description of already well-known matters and a duplicate description of substantially the same configuration may be omitted. . Further, the contents of the following description and the accompanying drawings are not intended to limit the subject matter described in the claims.

  The raw material gas liquefying apparatus according to the embodiment is an apparatus that cools a gaseous raw material gas supplied from the upstream side of the apparatus with a refrigerant, liquefies it, and discharges it as a liquefied raw material gas. In this embodiment, the raw material gas liquefied Take hydrogen gas as an example. However, the target source gas in the source gas liquefaction apparatus of the embodiment is not limited to hydrogen gas, is a gas at room temperature and normal pressure, and has a boiling point lower than the boiling point of nitrogen gas (−196 ° C.), For example, hydrogen gas, helium gas, and neon gas are equivalent.

  In FIG. 1, the schematic whole structure of the raw material gas liquefying apparatus 101 of this embodiment is shown. The raw material gas liquefying apparatus 101 is roughly divided into a feed line 110 for supplying hydrogen gas to be liquefied and a refrigerant circulation line for circulating a refrigerant for cooling the supplied hydrogen gas (also referred to as “recycling line”). And a control device 150 that performs operation control on the feed line 110 and the refrigerant circulation line 130 and performs hydrogen gas liquefaction amount correction control, and generates liquid hydrogen.

The raw material gas liquefying apparatus 101 includes a nitrogen line 170 for preliminary cooling of the raw material gas and the refrigerant, and a plurality of heat exchangers 180a to 180g (generic names) that exchange heat between the feed line 110 and the refrigerant circulation line 130. 181 may also be referred to as a heat exchanger 180). Here, the nitrogen line 170 is provided with a liquid nitrogen storage tank 171 for storing liquid nitrogen supplied from the outside, and a second stage heat exchanger 180 b is provided in the liquid nitrogen storage tank 171. The passage 111 of the feed line 110 and the outlet passage of the recycle high-pressure compressor 133 in the refrigerant circulation line 130 are connected to the second stage heat exchanger 180b. Therefore, the hydrogen gas flowing through the feed line 110 and the refrigerant circulating through the refrigerant circulation line 130 are cooled to near the liquid nitrogen temperature by the second-stage heat exchanger 180b.
These heat exchangers sequentially cool the hydrogen gas, which is a raw material gas, to a lower temperature in order from the first stage heat exchanger 180a to the sixth stage heat exchanger 180g. The hydrogen gas is cooled to a very low temperature in the stage heat exchanger 181.
These components will be sequentially described below.

First, the refrigerant circulation line 130 will be described.
In the refrigerant circulation line 130, a passage 131, a recycled low-pressure compressor 132, a recycled high-pressure compressor 133, a recycled inlet pressure control valve 134, a recycled line inlet pressure gauge 135, a recycled Joule-Thompson valve (referred to as “recycled JT valve”) 136), a high pressure expansion turbine 137, a low pressure expansion turbine 138, a low pressure expansion turbine outlet thermometer 139, and a liquid hydrogen storage tank 140. The passage 131 is a generic name including passages 131A and 131B described below.
In this embodiment, the refrigerant circulation line 130 uses the same hydrogen gas as the raw material gas as the refrigerant, and repeatedly circulates the cooling and liquefaction of the refrigerant, that is, the hydrogen gas in the closed loop. Although not shown, the refrigerant circulation line 130 is connected to a filling line for filling the refrigerant circulation line 130 with the refrigerant.

  Further, the refrigerant circulation line 130 transfers the refrigerant hydrogen gas in a gaseous state to generate cold heat, and liquefies the refrigerant hydrogen gas using the cold heat generated by the cold heat generation system 141. And a liquefaction system 142. The cold heat generation system 141 includes a high-pressure expansion turbine 137, a low-pressure expansion turbine 138, a low-pressure expansion turbine outlet thermometer 139, and a passage 131A. The liquefaction system 142 includes a recycled low-pressure compressor 132, a recycled high-pressure compressor 133, A recycling inlet pressure control valve 134, a recycling line inlet pressure gauge 135, a recycling system JT valve 136, a liquid hydrogen storage tank 140, and a passage 131B are included.

The liquefaction system 142 will be described. The recycled low-pressure compressor 132 and the recycled high-pressure compressor 133 are compressors that increase the pressure of hydrogen gas that circulates through the refrigerant circulation line 130. The recycled low-pressure compressor 132 and the recycled high-pressure compressor 133 are connected in series, The refrigerant flows from the recycled low-pressure compressor 132 to the recycled high-pressure compressor 133.
The outlet passage of the recycled high-pressure compressor 133 is connected to the first-stage heat exchanger 180a. Here, a bypass line that does not pass through the recycled high-pressure compressor 133 is provided between the inlet side and the outlet side of the recycled high-pressure compressor 133, and a recycled inlet pressure control valve 134 is installed in this bypass line. Therefore, the recycle inlet pressure control valve 134 adjusts the pressure of the refrigerant, that is, hydrogen gas supplied to the first-stage heat exchanger 180a by adjusting the valve opening degree by the control device 150. This pressure is measured by a recycle line inlet pressure gauge 135. That is, the recycle line inlet pressure gauge 135 is installed immediately before the first stage heat exchanger 180 a in the outlet passage of the recycle inlet pressure control valve 134, and sends the measured value to the control device 150.

The refrigerant leaving the first stage heat exchanger 180a is cooled to near the temperature of liquid nitrogen by the second stage heat exchanger 180b installed in the liquid nitrogen storage tank 171 described above, and the third stage heat exchanger. It is supplied to 180c and further cooled.
The outlet passage of the third-stage heat exchanger 180c is branched into a passage 131A that goes to the above-described cold heat generation system 141 and a passage 131B that goes to the heat exchanger in the subsequent stage. In the present embodiment, the design is such that most of the refrigerant that has exited the third-stage heat exchanger 180 c goes to the cold heat generation system 141.
The passage 131B toward the heat exchanger is sequentially connected from the fourth stage to the seventh stage heat exchangers 180d to 180g, and is connected to the recycle system JT valve 136. Therefore, the refrigerant flowing through the passage 131B is sequentially cooled in this order by the heat exchangers 180d to 180g.

The recycle JT valve 136 is installed at the inlet of the liquid hydrogen storage tank 140 on the outlet side of the seventh-stage heat exchanger 180g, and generates a low-temperature and high-pressure refrigerant hydrogen gas cooled by 180g from the series of heat exchangers 180a. Thomson (isoenthalpy) expands and liquefies to produce liquid hydrogen.
The liquid hydrogen storage tank 140 stores the generated liquid hydrogen. A final stage heat exchanger 181 is installed in the liquid hydrogen storage tank 140, and the passage 111 of the feed line 110 is connected to the heat exchanger 181. Therefore, the hydrogen gas flowing through the feed line 110 is cooled to near the liquid hydrogen temperature by the liquid hydrogen in the heat exchanger 181 and the liquid hydrogen storage tank 140.

  The liquid hydrogen storage tank 140 is connected to a passage 131Ba through which hydrogen gas vaporized from liquid hydrogen passes. The vaporized hydrogen gas passes through the seventh-stage heat exchanger 180g, the third-stage heat exchanger 180c, and the first-stage heat exchanger 180a in this order to raise the temperature, and enters the recycle low-pressure compressor 132 at the inlet. Led.

Next, the cold heat generation system 141 will be described.
As described above, the passage 131A branched on the outlet side of the third-stage heat exchanger 180c is connected to the inlet side of the high-pressure expansion turbine 137. Therefore, most of the refrigerant that has been pressurized by the recycle high-pressure compressor 133 and passed through the third-stage heat exchanger 180c is introduced into the high-pressure expansion turbine 137 side as described above by the operation of the high-pressure expansion turbine 137.
The high-pressure expansion turbine 137 passes through the heat exchanger 180c and lowers and lowers the pressure of the refrigerant at a temperature lower than the liquid nitrogen temperature by expansion. The outlet passage of the high-pressure expansion turbine 137 passes through the fifth-stage heat exchanger 180e and is connected to the inlet of the low-pressure expansion turbine 138. The high pressure expansion turbine 137 and the low pressure expansion turbine 138 are connected in series.

The low-pressure expansion turbine 138 further lowers and lowers the temperature of the low-temperature and high-pressure refrigerant guided from the high-pressure expansion turbine 137 by expansion. A low-pressure expansion turbine outlet thermometer 139 is installed in the outlet passage of the low-pressure expansion turbine 138, and the low-pressure expansion turbine outlet thermometer 139 measures the temperature of the refrigerant that has exited the low-pressure expansion turbine 138 and sends it to the controller 150. . In the present embodiment, the refrigerant that has exited the low-pressure expansion turbine 138 becomes cryogenic hydrogen gas.
In addition, the refrigerant that has exited the low-pressure expansion turbine 138 passes through the sixth-stage heat exchanger 180f, the third-stage heat exchanger 180c, and the first-stage heat exchanger 180a in this order to raise the temperature, and the recycle low-pressure The refrigerant is increased in pressure by the compressor 132 and returned to the inlet side of the recycled high-pressure compressor 133.

Next, the feed line 110 will be described.
The feed line 110 includes a passage 111, a feed compressor 112, a feed compressor outlet-side flow meter 113, a feed system JT valve inlet pressure gauge 114, a feed system JT valve inlet thermometer 115, and a feed system Joule Thomson valve (“feed” 116) (sometimes referred to as "system JT valve").
High purity hydrogen gas is supplied to the passage inlet of the feed line 110 from the upstream side of the raw material gas liquefying apparatus 101, and the feed compressor 112 boosts the hydrogen gas. Part of the pressurized hydrogen gas at normal temperature and high pressure is supplied to the turbine bearings of the expansion turbines 137 and 138 provided in the refrigerant circulation line 130 through a branch line provided in the passage 111 on the outlet side of the feed compressor 112. . A feed compressor outlet-side flow meter 113 is installed in a passage 111 between this branch point and the inlet of the first-stage heat exchanger 180a. The feed compressor outlet-side flow meter 113 is a series of heat exchangers. The flow rate of hydrogen gas at room temperature and high pressure immediately before being supplied from 180 a to 180 g and 181 is measured, and the measured value is sent to the control device 150.

  The passage 111 in the feed line 110 is also sequentially connected from the first stage heat exchanger 180a to the seventh stage heat exchanger 180g in order to exchange heat with the refrigerant circulating in the refrigerant circulation line 130 described above. As described above, it is connected to the final stage heat exchanger 181 installed in the liquid hydrogen storage tank 140. Further, the outlet passage of the heat exchanger 181 is connected to the feed system JT valve 116.

  The feed system JT valve 116 is disposed at the passage outlet of the feed line 110, and passes the high-pressure hydrogen gas cooled by 180g and 181 from the series of heat exchangers 180a, thereby passing the cryogenic high-pressure hydrogen gas. Jules Thomson (isoenthalpy) expands and liquefies to produce cryogenic and normal pressure liquid hydrogen. The amount of generated liquid hydrogen is adjusted by the control device 150 by controlling the opening degree of the feed system JT valve 116.

  The feed system JT valve inlet pressure gauge 114 and the feed system JT valve inlet thermometer 115 are installed in the passage 111 immediately before the feed system JT valve 116 and are supplied with a cryogenic high pressure before being supplied to the feed system JT valve 116. The pressure and temperature of the hydrogen gas are measured, and the measured value is sent to the control device 150. In FIG. 1, for convenience, the feed system JT valve inlet thermometer 115 is illustrated adjacent to the feed system JT valve 116, but the feed system JT valve inlet pressure gauge 114 and the feed system JT valve inlet thermometer 115 are illustrated. The positional relationship is not limited to the illustration.

  In the present embodiment, regarding the feed line 110 and the refrigerant circulation line 130 described above, the portion of the feed compressor 112 and the feed compressor outlet side flow meter 113 in the feed line 110 and the recycle low pressure in the refrigerant circulation line 130 are used. The components excluding the compressor 132, the recycled high-pressure compressor 133, the recycled inlet pressure control valve 134, and the recycled line inlet pressure gauge 135 are configured as a hydrogen liquefier 120. With this configuration, the recycle inlet pressure control valve 134 and the recycle line inlet pressure gauge 135 in the refrigerant circulation line 130 are arranged at the inlet portion to the hydrogen liquefier 120.

Here, the liquefaction operation of hydrogen gas in the feed line 110 by the heat exchangers 180a to 180g and 181 including the liquid nitrogen storage tank 171 and the liquid hydrogen storage tank 140 configured as described above will be described.
The high purity hydrogen gas supplied to the inlet of the feed line 110 is pressurized by the feed compressor 112. In the first stage heat exchanger 180a, the pressurized hydrogen gas at room temperature and high pressure is vaporized in the liquid nitrogen storage tank 171, refrigerant exiting the low-pressure expansion turbine 138 in the refrigerant circulation line 130, and in the refrigerant circulation line 130. Cooled with hydrogen gas vaporized in the liquid hydrogen storage tank 140, cooled with liquid nitrogen in the second stage heat exchanger 180b, and expanded turbine in the refrigerant circulation line 130 in the third to sixth stage heat exchangers 180c to 180f. Due to the cooling by 137, 138, in the seventh stage heat exchanger 180g, a refrigerant having a temperature near the liquid hydrogen temperature in the refrigerant circulation line 130 is used, and in the final stage heat exchanger 181 by the liquid hydrogen, almost liquid hydrogen is obtained. Cool to temperature. The cryogenic and high-pressure hydrogen gas that has passed through the heat exchanger 181 expands and liquefies by passing through the feed system JT valve 116, becomes liquid hydrogen at a cryogenic normal pressure, and is discharged from the raw material gas liquefying apparatus 101. . In addition, the liquefied raw material gas produced | generated and discharged | emitted by the said raw material gas liquefying apparatus 101 is hold | maintained at a storage tank, for example.

Next, the control device 150 will be described.
The control device 150 is a device that performs operation control relating to the feed line 110 and the refrigerant circulation line 130, and in this embodiment, is a device that particularly executes a method for correcting the liquefaction amount of the source gas. Although details of this raw material gas liquefaction amount correction control method will be described later, this method roughly includes an opening degree command 210 for the feed system JT valve 116 and an opening degree command 250 for the recycle inlet pressure control valve 134. . Therefore, the control device 150 has a control function portion that performs these two commands. For the sake of convenience, the control device 150 shown in FIG. 1 shows blocks denoted by reference numerals “210” and “250” as two control function parts.
Such a control device 150 is actually realized by using a computer, and each function described below including the above-described two control function parts is executed by corresponding software. Therefore, the control device 150 is composed of this software and hardware such as a CPU (central processing unit) and a memory for executing the software.

  The control device 150 is supplied with process data in the feed line 110 and the refrigerant circulation line 130, for example, flow rate, pressure, temperature, liquid level, rotation speed, valve opening degree, and the like. In this embodiment, in order to automatically correct and control (adjust) the liquefaction amount of the liquid hydrogen generated in the feed line 110, the raw material gas liquefying apparatus is further performed while preventing overcooling in the refrigerant circulation line 130 and insufficient cooling. In order to achieve the stable operation of 101, the following five measured values are important as process data supplied to the control device 150. That is, as described, the measured values from the feed compressor outlet flow meter 113, the feed system JT valve inlet pressure gauge 114, and the feed system JT valve inlet thermometer 115 installed in the feed line 110, and the refrigerant These are measured values from the recycle line inlet pressure gauge 135 and the low pressure expansion turbine outlet thermometer 139 installed in the circulation line 130.

The control device 150 uses these measured values to control the opening of the feed system JT valve 116 in the feed line 110 and the recycle inlet pressure control valve 134 in the refrigerant circulation line 130, and thereby the feed line 110 and the refrigerant circulation line. Appropriately control the process balance at 130.
As a result, the heat exchangers 180a to 180g and 181 in the raw material gas liquefying apparatus 101 and the feed gas and refrigerant flow rate decrease due to aging of the expansion turbines 137 and 138 and the compressors 132, 133 and 112 are fed. The liquefaction amount of the raw material gas in the line 110 and the circulating refrigerant amount in the refrigerant circulation line 130 are automatically adjusted, and a desired liquefaction amount of the raw material gas can be obtained without breaking the process balance in the raw material gas liquefying apparatus 101. it can. Further, even under a situation where the supply of the raw material hydrogen gas to the feed line 110 fluctuates, the amount of refrigerant is adjusted according to the amount of liquefied raw material gas, so that the process balance in the raw material gas liquefying apparatus 101 is stable without breaking. You can drive.

  Further, for example, the initial stage of operation, that is, the above-described heat exchangers 180 and 181, the expansion turbines 137 and 138, and the compressors 112, 132, and 133 are the same as new ones, or the upstream source gas is stably supplied without fluctuation. Under such conditions, the control device 150 determines the opening degree of the feed system JT valve 116 in the feed line 110 according to the measured value of the low-pressure expansion turbine outlet thermometer 139 among the above-described five measured values. The amount of liquefaction of the raw material gas generated in the feed line 110, that is, hydrogen gas in this embodiment, may be controlled.

  Hereinafter, the method for controlling the correction of the liquefaction amount of the source gas performed by the control device 150 will be described with reference to FIGS. 2 to 4, the measurement values obtained from the above-described five measuring instruments supplied to the control device 150 are described with reference to the reference numerals of the respective measuring instruments shown in FIG. 1.

FIG. 2 is a block diagram showing an operation configuration related to the method for controlling the correction of the liquefaction amount of the source gas.
As shown in the figure, the control device 150 finally performs an opening degree command 210 for the feed system JT valve 116 and an opening degree instruction 250 for the recycle inlet pressure control valve 134 using each process data.
First, the opening degree command 210 of the feed system JT valve 116 will be described.
As described above, the opening degree adjustment of the feed system JT valve 116 corresponds to the adjustment of the liquefaction amount of the hydrogen gas in the feed line 110. The amount of hydrogen gas liquefied in the feed line 110 is basically the low temperature expansion turbine outlet temperature set value 201 preset by the operator for the raw material gas liquefying apparatus 101 and the actual temperature of the low pressure expansion turbine outlet thermometer 139. It is determined by feedback control with the measured value. “Turbine outlet temperature control” 202 shown in FIG. 2 corresponds to this feedback control. Therefore, the most basic control method in the liquefaction amount correction control method is that the liquefaction amount of hydrogen gas, which is a raw material gas, according to the refrigerant temperature at the outlet of the low pressure expansion turbine 138 measured by the low pressure expansion turbine outlet thermometer 139. The control device 150 adjusts the opening degree of the feed system JT valve 116 according to the refrigerant temperature.
However, there may be a case where a desired amount of hydrogen gas liquefaction cannot be obtained from the feed line 110 only by the feedback control described above. Therefore, in the present embodiment, the following configuration is adopted in order to cope with such a situation.

  That is, if the actual temperature measurement value of the low-pressure expansion turbine outlet thermometer 139 is higher than the low-pressure expansion turbine outlet temperature setting value 201, the cooling state of the raw hydrogen gas is insufficient. Reduce the flow rate of the raw material hydrogen gas. On the other hand, if the actual temperature measurement value of the low-pressure expansion turbine outlet thermometer 139 is lower than the low-pressure expansion turbine outlet temperature set value 201, the feed hydrogen JT valve 116 is opened because the raw hydrogen gas is supercooled. Increase the flow rate of the raw material hydrogen gas.

  That is, as shown in FIG. 2, the opening degree command 210 of the feed system JT valve 116 is performed by adding the result of the opening degree correction calculation 230 of the feed system JT valve 116 to the feedback control described above.

The opening degree correction calculation 230 of the feed JT valve 116 is performed as follows.
As shown in FIG. 2, in the opening correction calculation 230 of the feed system JT valve 116, in this embodiment, the value of the opening command 210 for the feed system JT valve 116 one control cycle before (“MV_last” in the figure). Feed system JT valve opening (previous value) 221, measured values of the feed system JT valve inlet pressure gauge 114 and the feed system JT valve inlet thermometer 115, and feed compression in the feed line 110. Supplied with a deviation (may be described as “F_def” in the figure) 222 with respect to the set value of the machine outlet side flow rate and a flag (“1” or “0”) 224 instructing whether or not to perform a correction operation Is done. Here, the deviation 222 corresponds to the set flow rate value of the raw material gas, that is, hydrogen gas, at the feed compressor outlet side flow meter 113 corresponding to the load factor 223 set in advance by the operator for the raw material gas liquefying apparatus 101, This is a deviation from the flow rate of hydrogen gas (feedline liquefier inlet flow rate) at the compressor outlet side flow meter 113 portion. The set flow rate value is obtained by information indicating the relationship between the load factor 223 and the set flow rate value, for example, a table function.

Here, the load factor 223 is a ratio of the liquefaction amount when the refrigerant amount in the refrigerant circulation line 130 necessary for generating the rated liquefaction amount in the raw material gas liquefaction apparatus 101 is 100% load.
As will be described in detail below, the refrigerant amount in the refrigerant circulation line 130 is adjusted using the pressure value in the recycle line inlet pressure gauge 135 portion. Further, in this specification, the raw material gas that has passed through the feed compressor outlet-side flow meter 113 is liquefied in its entirety. Therefore, by setting the load factor, as shown in FIG. 2, the set flow rate of the raw material gas passing through the feed compressor outlet side flow meter 113 and the set pressure in the recycle line inlet pressure gauge 135 are set. The For example, when the load factor is 80%, the set flow value of the raw material gas, that is, the set liquefaction amount is basically 80% of the rated liquefaction amount, which is necessary to generate 80% of the rated liquefaction amount. The amount of refrigerant is determined by the recycle line inlet pressure.

FIG. 3 is a block diagram showing an operational configuration related to the opening degree correction calculation 230.
In the opening correction calculation 230, first, at step 225, based on the measured value P1 of the feed system JT valve inlet pressure gauge 114, the measured value T1 of the feed system JT valve inlet thermometer 115, and the value F_def of the deviation 222. Thus, a reference opening value CV_def serving as a correction reference for the feed system JT valve 116 is obtained. As an example of how to obtain it, an arithmetic expression shown in FIG. 3 is used. However, the calculation formula is not limited to this, and the method of obtaining the reference opening value CV_def is not limited to the method using the calculation formula.

  Next, based on the obtained reference opening value CV_def, in step 226, a corrected opening value MV_def of the feed system JT valve 116 is obtained. As an example of how to obtain the corrected opening value MV_def, in the present embodiment, as an example, the case where the relationship between the valve opening and the flow rate in the feed system JT valve 116 is not a linear proportional relationship is considered, for example, A valve opening degree is set, a correction coefficient is set in advance according to the valve opening degree corresponding to the previous value MV_last of the opening command 210 for the feed system JT valve 116, and the reference opening value CV_def is set to this correction coefficient. Is used to obtain a corrected opening value MV_def. Of course, the method of obtaining the corrected opening value MV_def is not limited to this method, and a known method can be adopted. For example, as an example, the relationship between the reference opening value CV_def and the corrected opening value MV_def is held in the form of a graph or a table, and using this, the corrected opening value MV_def is obtained from the obtained reference opening value CV_def. May be. Therefore, in this way of obtaining, it is not necessary to use the previous value MV_last.

  The obtained corrected opening value MV_def is selected to be output according to the liquefaction amount correction control execution flag 224 input in advance by the operator. When the flag 224 is “1”, the obtained MV_def is output and liquefaction amount correction control is performed. On the other hand, when the flag 224 is “0”, “0” is output and the liquefaction amount correction control is not performed. In other words, when it is “0”, the opening command of the feed system JT valve 116 is only obtained by feedback control of the low-pressure expansion turbine outlet temperature set value 201 and the actual temperature measurement value of the low-pressure expansion turbine outlet thermometer 139. 210 is determined.

  By executing the opening correction calculation 230 as described above, when the liquefaction amount of the hydrogen gas in the feed line 110 is larger than the liquefaction amount set in advance, the liquefaction amount is reduced by restricting the feed system JT valve 116. On the other hand, when the liquefaction amount is smaller than the preset liquefaction amount, the liquefaction amount can be increased by opening the feed system JT valve 116.

In the present embodiment, as described above, the opening correction calculation 230 is executed in consideration of the measured value T1 of the feed system JT valve inlet thermometer 115. However, since the measured value T1 does not significantly affect the calculation result even if the value fluctuates somewhat, the opening correction calculation 230 can be executed without considering the measured value T1.
Therefore, the opening degree correction calculation 230 of the feed system JT valve 116 is, at a minimum, the measured value P1 of the feed system JT valve inlet pressure gauge 114 and the inlet flow rate and load factor at the feed compressor outlet side flow meter 113 portion. The deviation 222 from the corresponding flow rate set value of the feed line 110 can be used.

Next, the opening degree command 250 of the recycle inlet pressure control valve 134 will be described.
Adjustment of the opening degree of the recycle inlet pressure control valve 134 corresponds to adjusting the amount of refrigerant circulating through the refrigerant circulation line 130 as already described.
The amount of the refrigerant circulating through the refrigerant circulation line 130 is basically determined based on the load factor 223 set in advance by the operator for the raw material gas liquefying apparatus 101, and the recycle line inlet pressure gauge of the refrigerant circulation line 130. It is determined by feedback control between the liquefier inlet pressure set value at 135 and the actual pressure measured value from the recycle line inlet pressure gauge 135.
However, there may be a case where a desired amount of liquefied hydrogen gas cannot be obtained from the feed line 110 with the amount of refrigerant corresponding to the set load factor 223. Therefore, in the present embodiment, the following configuration is adopted in order to cope with such a situation.

  That is, as shown in FIG. 2, the set liquefaction amount of the raw material gas, that is, hydrogen gas, in the feed line 110 corresponding to the load factor 223, and the flow rate of the hydrogen gas in the feed compressor outlet side flow meter 113 (feed line) The Δ load factor 241 corresponding to the increase / decrease amount of the load factor 223 is obtained from the deviation from the liquefier inlet flow rate (step 240).

Here, step 240 will be described with reference to FIG.
As already described, a load factor 223 is set in advance in the raw material gas liquefier 101 by an operator, and a set flow rate value of hydrogen gas corresponding to the load factor 223 in the feed compressor outlet-side flow meter 113 portion, A deviation 222 from the actual measured flow rate value of the hydrogen gas in the feed compressor outlet side flow meter 113 is obtained. In step 240, how much the deviation 222 deviates from the flow rate value of hydrogen gas corresponding to the set load factor, that is, the rated flow rate, in other words, what percentage deviation corresponds to the deviation 222 in the load factor, Ask for. The obtained value corresponds to the deviation in the load factor, and is assumed to be Δ load factor 241. Whether or not to output the Δ load factor 241 can be selected by the flag 224 described above. When the flag 224 is “1”, the obtained deviation is output as the Δ load factor 241. When 224 is “0”, “0” is output as the Δ load factor 241. That is, when the Δ load factor 241 is “0”, the liquefier inlet pressure setting value in the recycling line inlet pressure gauge 135 portion of the refrigerant circulation line 130 and the actual pressure measurement value from the recycling line inlet pressure gauge 135 are displayed. With this feedback control alone, the opening degree command 250 for the recycle inlet pressure control valve 134 is determined.

In the next step 242, the obtained Δ load factor 241 is added to the above-described load factor 223 to set a “correction load factor”.
In the next step 243, the recycle line inlet pressure gauge for the set "corrected load ratio" from the relationship information prepared in advance between the corrected load factor and the liquefier inlet pressure set value in the recycle line inlet pressure gauge 135 portion. The pressure set value 244 at the 135 portion is obtained. Here, as the relation information prepared in advance, for example, a table function or the like can be used.
In the next step 245, the control device 150 controls the recycle inlet pressure control valve 134 of the refrigerant circulation line 130 so that the actual measured pressure value of the refrigerant obtained from the recycle line inlet pressure gauge 135 approaches the pressure set value 244. Adjust the opening.

  By adjusting the opening degree, the amount of refrigerant circulating through the refrigerant circulation line 130 is adjusted as described above. Furthermore, in the present embodiment, by using the Δ load factor 241, when the liquefaction amount of the hydrogen gas is larger than the desired liquefaction amount in the feed line 110, the refrigerant circulation is increased by increasing the set load factor. If the amount of refrigerant circulating in the line 130 is increased while the liquefaction amount of hydrogen gas is smaller than the desired liquefaction amount, the refrigerant load circulating in the refrigerant circulation line 130 is reduced by lowering the set load factor. The amount can be reduced. As a result, it is possible to maintain the process balance in the raw material gas liquefying apparatus 101.

As described above, according to the raw material gas liquefying apparatus 101 of the present embodiment, by having the apparatus configuration shown in FIG. 1 and applying the raw material gas liquefaction amount correction control method shown in FIGS. The following effects can be obtained.
That is, the flow rates of the raw material gas and the refrigerant are reduced due to aging deterioration in the heat exchangers 180a to 180g and 181 provided in the raw material gas liquefying apparatus 101, and the expansion turbines 137 and 138 and the compressors 112, 132, and 133. Even if this occurs, the amount of raw material gas liquefied in the feed line 110 and the amount of refrigerant circulating in the refrigerant circulation line 130 can be automatically adjusted. As a result, a desired liquefaction amount of the source gas can be obtained without breaking the process balance in the source gas liquefying apparatus 101.
In addition, the amount of refrigerant circulating in the refrigerant circulation line 130 may be automatically adjusted according to the amount of raw material gas liquefied in the feed line 110 even under circumstances where the supply of the raw material gas to the feed line 110 fluctuates. it can. As a result, stable operation, that is, stable production of liquefied raw material gas can be performed without losing the process balance in the raw material gas liquefying apparatus 101.

  In the above-described embodiment, the refrigerant circulation line 130 includes two units of the recycled high-pressure compressor 133 and the recycled low-pressure compressor 132, and also includes two units of the high-pressure expansion turbine 137 and the low-pressure expansion turbine 138. However, these numbers depend on the performance of the compressor and the expansion turbine, and are not limited to two.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a raw material gas liquefying apparatus that liquefyes a raw material gas that is liquefied at a very low temperature such as hydrogen gas, using cold heat generated in a refrigerant circulation line, and a liquefaction amount correction control method for the raw material gas It is.

101 ... Raw material gas liquefier, 110 ... Feed line,
113 ... Feed compressor outlet side flow meter, 114 ... Feed system JT valve inlet pressure gauge,
115 ... Feed system JT valve inlet thermometer, 116 ... Feed system JT valve,
130: Refrigerant circulation line, 138: Low-pressure expansion turbine,
139 ... Low pressure expansion turbine outlet thermometer, 141 ... Cold heat generation system, 142 ... Liquefaction system,
150 ... control device,
222: Deviation, 230: Opening correction calculation.

Claims (10)

In a raw material gas liquefying apparatus that has a feed line for supplying a raw material gas whose boiling point is lower than that of nitrogen gas and a refrigerant circulation line for circulating a refrigerant for cooling the raw material gas, and liquefys the raw material gas,
The refrigerant circulation line includes a cold heat generation system, the cold heat generation system is transferred in a gas state without liquefying the refrigerant, has an expansion turbine for expanding the refrigerant, and generates cold.
A raw material gas liquefying apparatus, comprising: a control device that controls a liquefaction amount of the raw material gas in accordance with an outlet side refrigerant temperature of the expansion turbine. The refrigerant circulation line further includes a liquefaction system for liquefying the refrigerant using the cold generated by the cold generation system,
2. The raw material gas liquefying apparatus according to claim 1, wherein the feed line has a Joule-Thompson valve for liquefying the raw material gas cooled by the refrigerant liquefied in the liquefaction system by Joule-Thompson expansion.   The control device adds a correction calculation result to the opening of the Joule-Thompson valve in the feed line obtained by feedback control of the outlet-side refrigerant temperature of the expansion turbine and a set value of the outlet-side refrigerant temperature, The raw material gas liquefying apparatus according to claim 2, wherein the liquefaction amount of the raw material gas is controlled by correcting the opening of the Thomson valve.   The Joule Thomson valve opening correction calculation uses the deviation between the inlet pressure of the Joule Thomson valve in the feed line and the flow rate set value of the feed line according to the inlet flow rate and load factor of the feed line. The raw material gas liquefying apparatus according to claim 3, which is performed.   The raw material gas liquefying apparatus according to claim 4, wherein an inlet temperature of the Joule Thomson valve in the feed line is further added to an opening correction calculation of the Joule Thomson valve.   6. The source gas according to claim 1, wherein the control device further controls the amount of the refrigerant circulating in the refrigerant circulation line using a deviation between the inlet flow rate of the feed line and the flow rate set value. Liquefaction device.   The control of the circulating refrigerant amount by the control device obtains the deviation between the inlet flow rate of the feed line and the flow rate set value as an increase / decrease amount with respect to the set liquefaction rate in the source gas liquefaction device, and the refrigerant circulation line according to the increase / decrease amount. The raw material gas liquefying apparatus according to claim 6, wherein the amount of refrigerant circulating in the refrigerant is controlled. Executed in a raw material gas liquefier having a feed line for supplying a raw material gas for liquefaction whose boiling point is lower than that of nitrogen gas, a refrigerant circulation line for circulating a refrigerant for cooling the raw material gas, and a control device In the source gas liquefaction amount correction control method,
The refrigerant circulation line includes a cold heat generation system, the cold heat generation system is transferred in a gas state without liquefying the refrigerant, has an expansion turbine for expanding the refrigerant, and generates cold.
The control device corrects and controls the liquefaction amount of the raw material gas in accordance with the outlet side refrigerant temperature of the expansion turbine.   The raw material gas liquefaction amount correction according to claim 8, wherein the control device further controls the amount of refrigerant circulating in the refrigerant circulation line using a deviation between the inlet flow rate of the feed line and the flow rate set value. Control method.   The control of the amount of refrigerant circulating in the refrigerant circulation line is performed by obtaining the deviation between the inlet flow rate of the feed line and the flow rate setting value as an increase / decrease amount with respect to the set liquefaction rate in the raw material gas liquefaction device. The method for correcting the amount of liquefaction of a source gas according to claim 9, wherein the amount of refrigerant circulating in the line is controlled.

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