JP2017180573A - Gas supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas supply system capable of easily transporting LPG.SOLUTION: A gas supply system includes: a gas main pipe configured to transport first urban gas containing methane gas and hydrocarbon system gas having 2 or more carbon atoms; and a separator connected to the gas main pipe, and configured to separate the first urban gas into the hydrocarbon system gas having the 2 or more carbon atoms and second urban gas in which the hydrocarbon system gas having the 2 or more carbon atoms is removed from the first urban gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas supply system.

Conventionally, a raw material gas containing at least methane and hydrocarbons having a lower volatility than methane is obtained by using a distillation column, and a residual gas enriched in methane and thinner in hydrocarbons having a lower volatility than methane, In a hydrocarbon separation process that separates into a heavier fraction enriched in hydrocarbons that are thinner and less volatile than methane,
(A) a step of cooling the raw material gas, condensing a part of the raw material gas and separating the gas and liquid;
(B) supplying the liquid obtained in step (a) to a distillation column;
(C) a step of expanding the gas obtained in step (a) with an expander, condensing a part of the gas, and separating the gas and liquid;
(D) supplying the liquid obtained in step (c) to the distillation column;
(E) a step of branching the gas obtained in step (c) into a first portion and a second portion;
(F) supplying the first portion to the distillation column;
(G) compressing and cooling the second part, condensing it and then supplying it to the distillation column as reflux;
(H) There is a hydrocarbon separation method characterized by having a step of obtaining the residual gas from the top of the distillation column and obtaining the heavy fraction from the bottom of the distillation column (for example, Patent Documents) 1).

Japanese Patent No. 4442239

  By the way, the conventional hydrocarbon separation method uses ethane or LPG (liquefied petroleum gas) from raw gas such as LNG (Liquefied Natural Gas) using ultra-low temperature of about -162 ° C. In order to carry out the cryogenic separation, the place where the separation apparatus for realizing the conventional hydrocarbon separation method can be installed is in the LNG terminal or in an adjacent area.

  For this reason, for example, in a case where the LNG base and the petrochemical plant are separated, a means for transporting LPG between the separation device and the petrochemical plant is required. Unlike city gas, LPG alone is not suitable for long-distance transportation in a high-pressure pipeline, and is therefore transported by tank truck.

  In addition, about 80% of LPG is covered by imports from overseas and accepted at import bases in the Gulf area. The remaining 20% is taken out when refining crude oil with domestic crude oil refineries, but since crude oil is also imported, almost all crude oil refineries are deployed in the Gulf region. LPG obtained from crude oil is also stored at a base in the Gulf area.

  As described above, LPG alone is not suitable for long-distance transportation in a high-pressure pipeline. This is because LPG in a liquefied state mainly composed of propane and butane is liquefied when it exceeds 1 MPa, and when it is transported alone in a pipeline, it may vaporize when the pressure drops due to pressure loss or the like. It is.

  Therefore, LPG is stored at import bases in the Gulf region, and when transported to various places in the country, it is transported by tank truck.

  For this reason, in the conventional hydrocarbon separation method, there is a problem that the transport efficiency of LPG is poor and troublesome.

  Then, it aims at providing the gas supply system which can convey LPG easily.

  A gas supply system according to an embodiment of the present invention is connected to a gas main that transports a first city gas including methane gas and a hydrocarbon-based gas having 2 or more carbon atoms, and is connected to the gas main. A separator that separates the first city gas into the hydrocarbon gas having 2 or more carbon atoms and the second city gas obtained by removing the hydrocarbon gas having 2 or more carbon atoms from the first city gas. Including.

  A gas supply system capable of easily transporting LPG can be provided.

1 is a diagram showing a gas supply system 100 and an LNG base 10. FIG. It is a figure which shows the structure of the separator 110 and its periphery. 4 is a diagram for explaining the flow of energy in the petrochemical plant 80. FIG. It is a figure explaining the flow of energy in 80 A of petrochemical plants which are not provided with the gas supply system 100 for the comparison. It is a figure which shows gas supply system 100A, 100B of Embodiment 2. FIG. It is a figure which shows gas supply system 100A, 100B of Embodiment 2. FIG.

  Embodiments to which the gas supply system of the present invention is applied will be described below.

<Embodiment 1>
FIG. 1 is a diagram showing a gas supply system 100 and an LNG base 10.

  The LNG base 10 includes tanks 11 </ b> A and 11 </ b> B, a calorific value adjustment device 12, and a vaporizer 13. As an example, the LNG base 10 is located in the bay area, and stores LNG and LPG imported by tanker transportation in the tanks 11A and 11B, respectively. Here, the bay area refers to an area where a tanker can come to berth and LNG and LPG can be transferred from the tanker to the tanks 11A and 11B. The inland area refers to an inland area from the gulf.

  The calorific value adjusting device 12 is connected between the tanks 11A and 11B and the vaporizer 13, and by adding LPG supplied from the tank 11B to LNG supplied from the tank 11A, Adjust the amount of heat.

  The vaporizer 13 vaporizes the mixed gas whose calorific value has been adjusted by the calorific value adjusting device 12 and outputs it to the pipeline 120.

  Here, since LNG (Liquefied Natural Gas: liquefied natural gas) is a natural gas, it contains hydrocarbon gases such as methane, ethane, propane, or butane. LPG (liquefied petroleum gas) is a gas mainly composed of propane and butane, and may contain hydrocarbon gases other than propane and butane.

  As an example, the ratio of LPG in the mixed gas of LNG and LPG is less than 5%. The mixed gas of LNG and LPG is a gas transported by the pipeline 120 as the city gas A. The city gas A contains about several percent of LPG component for heat quantity adjustment. The mixed gas of LNG and LPG is an example of the first city gas.

  Here, a mode in which the city gas A is a mixed gas of LNG and LPG will be described. However, the city gas A is a gas containing methane gas and a hydrocarbon-based gas having 2 or more carbon atoms. Good.

  However, depending on the gas utilization mode, a case where a gas not mixed with LPG (unheated gas) is supplied rarely occurs.

  The gas supply system 100 includes a separation device 110 and a pipeline 120. As an example, the separation device 110 is located in an inland area or a bay area away from the bay area. When the separation device 110 is in an inland area, for example, the separation device 110 is arranged in an LPG generation base. Further, when the separation device 110 is in a bay area, for example, the separation device 110 is located in or near the petrochemical plant.

  The separation device 110 is connected to the vaporizer 13 of the LNG base 10 in the coastal region via the pipeline 120. Separation device 110 is a device that separates city gas A into city gas B and LPG.

  The city gas B is a C1 (methane) rich gas having a higher methane ratio than the city gas A. The city gas B separated by the separation device 110 is an example of a second city gas.

  As the separation device 110, for example, a separation device having a separation membrane for separating LPG from city gas A can be used. In addition, as the separation device 110, a separation device such as a PSA (Pressure Swing Adsorption) device may be used.

  The pipeline 120 is a gas main pipe that connects the inland separation device 110 and the vaporizer 13 of the LNG base 10 in the bay area. As an example, when the LNG base 10 is located in Tokyo Bay, when the separation device 110 is deployed in an inland area, the separation device 110 is located in the northern Kanto region.

  For this reason, the pipeline 120 is a gas main pipe that connects Tokyo Bay to North Kanto as an example. The gas main pipe is a gas pipe buried in parallel with the road and may be referred to as a high-pressure main line, a conduit, or a main branch pipe.

  In addition, when the LNG base 10 is located in the bay area of Tokyo Bay, when the separation apparatus 110 is also deployed in the bay area, the separation apparatus 110 is located, for example, in the bay area of Tokyo Bay. In this case, the pipeline 120 is a gas main pipe that connects the LNG base 10 and the separation device 110 in the bay area of Tokyo Bay.

  FIG. 2 is a diagram illustrating a configuration of the separation device 110 and its surroundings.

  Separator 110 includes separator 111, gas pipes 120A, 120B, 120C, pressure reducing device 131, pressure gauge 132, flow rate adjusting device 133, shutoff valve 134, bypass line 135, shutoff valve 135A, pressure gauge 136, flowmeter 137, The pressure reducing device 138 includes a check valve 139, a pressure gauge 151, a shutoff valve 152, a gas pipe 153, a GC (Gas Chromatograph) 154, a valve 155, a valve 156, a gas pipe 157, and a valve 158.

  As an example, the separator 111 is of a type having a separation membrane. For this reason, the separator 111 is referred to as a separation membrane (Membrane). Separator 111 is a separator that separates city gas A into city gas B and LPG.

  A gas pipe 120A is provided between the separator 111 and the pipeline 120, and a pressure reducing device 131, a pressure gauge 132, a flow rate adjusting device 133, and a shut-off valve 134 are provided in the gas pipe 120A. Further, a bypass line 135 is connected in parallel to the separator 111, and a shutoff valve 135A is provided in the bypass line 135.

  Separator 111 has two output ports, and boiler 140 is connected to one through gas pipe 120B. The gas pipe 120B is provided with a pressure gauge 136, a flow meter 137, a pressure reducing device 138, and a check valve 139.

  A liquefying device 150 is connected to the other output port of the separator 111 via a gas pipe 120C. A pressure gauge 151 and a shutoff valve 152 are provided in the gas pipe 120C.

  Further, a GC (Gas Chromatograph) 154 is connected to the flow rate adjusting device 133 via a gas pipe 153. A valve 155 is provided in the gas pipe 153 between the flow rate adjusting device 133 and the GC 154.

  The gas pipe 153A connecting the gas pipe 120C and the gas pipe 153 is provided with a valve 156, and the gas pipe 157 connecting the gas pipe 120C and the GC 154 is provided with a valve 158. It has been.

  The decompression device 131 is a device that lowers the pressure before the city gas A transported through the pipeline 120 is introduced into the separator 111. The city gas A is a city gas that is transported from the LNG base 10 (see FIG. 1) by the pipeline 120, and is a gas that contains several percent (less than about 5%) of LPG for heat quantity adjustment.

  The pressure gauge 132 measures the pressure of the city gas A decompressed by the decompression device 131. The flow rate adjustment device 133 is a device that adjusts the flow rate of the city gas A decompressed by the decompression device 131.

  The shut-off valve 134 is provided between the flow control device 133 and the separator 111 and is used when switching between the separator 111 and the bypass line 135. When operating the separator 111, the shut-off valve 134 is opened and the shut-off valve 135A of the bypass line 135 is shut off.

  The bypass line 135 is connected in parallel with the separator 111 and is used when bypassing the separator 111. The bypass line 135 is provided with a shutoff valve 135A. When bypassing the separator 111, the shutoff valve 134 is shut off and the shutoff valve 135A is opened.

  The pressure gauge 136 measures the pressure of the city gas B on the output side of the separator 111. The city gas B is a gas (C1 rich gas) which is purified from the city gas A by the separator 111 and hardly contains LPG. City gas B is mainly composed of methane.

  The flow meter 137 measures the flow rate of the city gas B output from the separator 111. The decompression device 138 decompresses the pressure of the city gas B output from the separator 111. The check valve 139 is provided to prevent a back flow between the separator 111 and the boiler 140.

  The boiler 140 is an example of an apparatus that uses city gas B.

  The liquefying device 150 is provided to liquefy the LPG separated by the separator 111. The liquefying device 150 pressurizes LPG at room temperature to liquefy it. The LPG liquefied by the liquefying device 150 is transported by a tank lorry, or is placed in a container for propane gas and supplied to the inside or outside of the petrochemical plant 80.

  The pressure gauge 151 is provided in the gas pipe 120 </ b> C connecting the separator 111 and the liquefaction device 150, and detects the pressure of the LPG separated by the separator 111. In addition, a shutoff valve 152 is provided in the gas pipe 120C.

  The gas pipe 153 connects between the flow rate adjusting device 133 and the GC 154 and is provided with a valve 155. When the GC 154 analyzes the city gas A, the valve 155 is opened and the city gas A is supplied to the GC 154. Valve 155 is otherwise blocked.

  The GC 154 is an analytical instrument used for gas identification and quantification. The city gas supplied from the flow control device 133 via the gas pipe 153 and the LPG supplied from the gas pipe 120C via the gas pipe 153A are added to the GC 154, or the city supplied via the gas pipe 157 is added to the GC 154. Either gas (C1 rich gas) is input, and the input gas is identified and quantified.

  The valve 156 is provided in the gas pipe 153A that connects the gas pipe 120C and the GC 154, and is opened when the LPG is analyzed by the GC 154, and is blocked in other cases.

  The gas pipe 157 is a gas pipe that connects the gas pipe 120B and the GC 154. The gas pipe 157 is provided with a valve 158.

  When the GC 154 analyzes the city gas B, the valve 158 is opened and the city gas B is supplied to the GC 154. Valve 158 is otherwise blocked.

  When the separator 111 is operated to purify the city gas B from the city gas A, and the LPG is separated, the shutoff valve 135A is shut off and the valves 155, 156, 158 are shut off.

  FIG. 3 is a diagram for explaining the flow of energy in the petrochemical plant 80. In FIG. 3, the flow of energy utilization when the separation device 110 is incorporated in the petrochemical plant 80 in the bay area will be described.

  In FIG. 3, the petrochemical plant 80 shows a hydrogen production apparatus 170 and an ethylene / propylene production apparatus 180 in addition to the boiler 140, and components of the gas supply system 100 are omitted except for the separation apparatus 110 and the pipeline 120. To do.

  In FIG. 3, the petrochemical plant 80 is supplied with LPG 191 and naphtha (crude gasoline) 192 as raw materials. The LPG 191 and the naphtha 192 are supplied to the hydrogen production apparatus 170 and the ethylene / propylene production apparatus 180 as an example.

  The city gas A supplied to the separation device 110 via the pipeline 120 is separated into city gas B and LPG, the city gas B is supplied to the boiler 140 and the hydrogen production device 170, and the LPG together with the LPG 191 The hydrogen is supplied to the hydrogen production apparatus 170 and the ethylene / propylene production apparatus 180. Note that the city gas A may be supplied to the boiler 140 together with the off-gas without passing through the separation device 110.

  Here, the off-gas refers to a gas containing hydrocarbons that are released unused but not used as raw materials and fuels in an ethylene / propylene production apparatus.

  The hydrogen produced by the hydrogen production apparatus 170 for desulfurization can be used, for example, in a petrochemical plant 80, for example, in a fuel cell. Further, hydrogen may be sold to other companies in the vicinity of the petrochemical plant 80.

  Off-gas generated in the process of producing ethylene and / or propylene by the ethylene / propylene production apparatus 180 is supplied to the boiler 140 and the hydrogen production apparatus 170. This off-gas can be supplied to the boiler 140 together with part of the city gas A transported by the pipeline 120.

  FIG. 4 is a diagram illustrating the flow of energy in a petrochemical plant 80A that does not include the gas supply system 100 for comparison.

  The LPG 191 and the naphtha 192 are supplied to the hydrogen production apparatus 170 and the ethylene / propylene production apparatus 180.

  Off-gas generated in the process of producing ethylene and / or propylene by the ethylene / propylene production apparatus 180 is supplied to the boiler 140 and the hydrogen production apparatus 170.

  The hydrogen produced by the hydrogen production apparatus 170 and the off-gas obtained from the ethylene / propylene production apparatus 180 are used inside the petrochemical plant 80A and can be sold to other companies in the vicinity of the petrochemical plant 80A.

  As can be seen by comparing FIG. 3 and FIG. 4, in the system of the first embodiment (FIG. 3), LPG separated from the city gas A by the separation device 110 is added to the LPG 191 to generate the hydrogen production device 170 and ethylene / propylene. Since it is supplied to the manufacturing apparatus 180, the amount of LPG 191 can be reduced compared to the case of FIG. 4, and LPG purified by the petrochemical plant 80 can be used.

  Further, the amount of naphtha 192 can be reduced as compared with the system of FIG. 4 by the amount that the LPG generated by the separation device 110 can be used.

  Further, since the city gas B rich in methane can be supplied to the hydrogen production apparatus 170, the production of hydrogen is facilitated.

  Further, part of the city gas A can be used as fuel for the boiler 140.

  In the system shown in FIG. 3, by using a separation gas (city gas B) rich in C1 (methane) as a raw material gas of the hydrogen production apparatus 170, compared with an off gas containing a C2 (ethane) component, Manufacturing efficiency is improved.

  By using a C1-rich (methane) separation gas (city gas B) as the raw material gas of the hydrogen production apparatus 170, hydrogen can be produced stably even if the amount of off-gas varies.

  In the prior art, since LNG needs to be cooled in order to separate and manufacture LPG, the separation and manufacturing of LPG is subject to a location restriction that it is adjacent to the LNG base. On the other hand, if LPG is separated and manufactured using the separation apparatus 110 of the separation membrane type, there is no location restriction and it can be installed in a petrochemical plant where there is much demand for LNG because no cooling is required. become.

  Since the location restriction of the LPG separation device 110 is eliminated, the LPG (LPG component gas) separated by the separation device 110 can be accommodated in a plurality of neighboring petrochemical plants using dedicated conduits.

  Further, the city gas A manufactured at the LNG base 10 and transported by the pipeline 120 to the petrochemical plant 80 is converted into C1 (methane) using a separation membrane type separation device 110 installed in the petrochemical plant 80. Separation into rich city gas A and C3 (propane) and C4 (butane) rich LPG (LPG component gas).

  The C1 (methane) rich gas is supplied to a hydrogen production apparatus for desulfurization in the adjacent petrochemical plant 80, thereby improving the hydrogen production efficiency. It is also supplied to boilers, heating furnaces, and generators at nearby factories. On the other hand, the separated C3 (propane) and C4 (butane) rich LPG component gas can be used as a raw material gas for the ethylene / propylene production apparatus 180 and a fuel gas for various heating apparatuses.

  In the petrochemical plant 80, the off-gas whose flow rate and properties are not stable is mainly used as a fuel gas for a heating heat source for the boiler 140, and the hydrogen production apparatus 170 mainly has C1 (methane) rich separated from the city gas A. Use of the city gas B can be expected to improve the production efficiency of hydrogen gas.

  The comparative petrochemical plant 80A shown in FIG. 4 uses LPG or naphtha as a raw material for the ethylene / propylene production apparatus 180, and converts off-gas generated from the ethylene / propylene production apparatus 180 into a raw material gas for the hydrogen production apparatus 170 and heating. It is used as a fuel gas.

  In the petrochemical plant 80 of the first embodiment shown in FIG. 3, C1 (methane) rich gas (city gas B) separated and manufactured from city gas A is used as a raw material gas for the hydrogen production apparatus 170 and a fuel as a heat source for heating the boiler 140. Use as gas. Further, L3 (LPG gas) rich in C3 (propane) and C4 (butane), which is the other component separated from the city gas A, is used as a raw material gas for the ethylene / propylene production apparatus 180.

  Moreover, although the form which transports the city gas A which adjusted the calorie | heat amount with the calorie | heat amount adjusting device 12 with the pipeline 120 was demonstrated above, when the LNG base 10 does not include the calorie | heat amount adjuster 12, as a city gas A, Gas that has not been subjected to heat adjustment (unheated gas) may be transported through the pipeline 120.

  This is because even an unheated gas contains components other than methane (a hydrocarbon gas having 2 or more carbon atoms). By supplying the unheated gas to the off-gas line, it can be used as a raw material gas for the hydrogen production apparatus 170 and a fuel gas for the boiler 140.

  In addition, C3 (propane) and C4 (butane) rich LPG separated by the separation device 110 installed in the petrochemical plant 80 is supplied to multiple plants in the complex area using dedicated conduits, and raw material gas and fuel are supplied to the multiple plants. It may be used as a gas.

  In addition, when it is necessary to stabilize the calorific value of C3 (propane) or C4 (butane) rich LPG supplied through a dedicated conduit, the calorimeter of the LPG after separation and C1 (methane) rich gas (city gas B) The LPG having a stable calorific value may be supplied through a dedicated conduit by combining the injection devices in FIG.

  In addition, the purity of the hydrogen gas produced by the hydrogen production apparatus 170 using C1 (methane) rich gas (city gas B) as a raw material is refined to high purity hydrogen gas using PSA or a separation membrane, and a hydrogen station for a fuel cell vehicle May be supplied. Alternatively, high-purity hydrogen gas may be supplied to a neighboring petrochemical plant using a dedicated conduit.

  As described above, according to the first embodiment, the city gas A is transported from the LNG base 10 in the bay area to the gas supply system 100 through the pipeline 120 (gas main). The pipeline 120 is an existing facility, and extends from the area where the LNG base 10 in the bay area is located to people. Further, the city gas A transported by the pipeline 120 contains about several percent of the LPG component for heat quantity adjustment.

  For this reason, if city gas A is separated into city gas B and LPG by the separation device 110 of the gas supply system 100, LPG can be obtained inland. For example, the LPG may be enclosed in a cylinder and sold to a household in a neighboring area. In this case, the location where the separation device 110 is located is the LPG generation base. Moreover, what is necessary is just to consume city gas B with the boiler 140 grade | etc., For example.

  Further, LPG may be used inside the petrochemical plant 80 or may be used in an area where the petrochemical plant 80 exists. When used in an area where the petrochemical plant 80 exists, it can play a role as an LPG supply source in the area.

  Conventionally, LPG is transported by tank lorries and used in the petrochemical plant 80, or LPG is transported by tank lorries to an inland LPG production base and packed in a domestic cylinder for sale.

  In contrast, in the first embodiment, the city gas A can be transported anywhere by the pipeline 120, and the city gas A can be separated into the city gas B and the LPG by the separation device 110 provided at the transport destination. it can.

  For this reason, if the separation apparatus 110 is prepared, LPG can be obtained anywhere in the region where the pipeline 120 is embedded. Since it is transported by the pipeline 120, LPG can be transported more easily than when LPG is transported by a tank lorry as in the prior art.

<Embodiment 2>
5 and 6 are diagrams showing gas supply systems 100A and 100B according to the second embodiment.

  A gas supply system 100A shown in FIG. 5 includes separation devices 110A, 110B, and 110C, decompression devices (self-powered) 131A, 131B, and 131C, pressure gauges 132A, 132B, and 132C, and a flow meter 201.

  The separation devices 110A, 110B, and 110C are connected in parallel to each other. The separation devices 110A, 110B, and 110C are connected in series with the decompression devices 131A, 131B, and 131C and the pressure gauges 132A, 132B, and 132C, respectively.

  One flow meter 201 is provided for the three separation devices 110A, 110B, and 110C, and detects the flow rate of the city gas B output from the separation devices 110A, 110B, and 110C. In FIG. 5, illustration of the LPG separated by the separation devices 110A, 110B, and 110C is omitted.

  The gas supply system 100A sequentially operates the separators 110A, 110B, and 110C by controlling the operation of the decompression devices (self-powered) 131A, 131B, and 131C connected in parallel with the flow rate of the city gas A. is there. It is a system characterized in that a special control device is not required by using a decompression device (self-powered). In the gas supply system 100A, the pressure ranges in which the decompression devices (self-powered) 131A, 131B, and 131C are decompressed are set to increase in the order of the decompression devices 131A, 131B, and 131C. That is, the pressure range in which the decompression device 131A decompresses is the lowest, and the pressure range in which the decompression device 131C decompresses is set to the highest.

  When the flow rate of the city gas A increases, the pressure detected by the pressure gauges 132A, 132B, 132C installed on the secondary side of the decompression device (self-powered) decreases, so the set pressure of the decompression device (self-powered) is 110A. 110B, 110C in this order, and the separators 110A, 110B, 110C are operated in order by the operation of the decompression device (self-powered) according to the flow rate.

  When the pressure detected by the pressure gauge 132A is less than the first predetermined value, the control device 200A turns on the decompression device 131A and turns off the decompression devices 131B and 131C in order to operate only the separation device 110A. .

  When the pressure detected by the pressure gauges 132A and 132B is not less than the first predetermined value and less than the second predetermined value, the control device 200A turns on the pressure reducing devices 131A and 131B to operate the separation devices 110A and 110B. And the pressure reducing device 131C is turned off.

When the pressure detected by the pressure gauges 132A and 132B is equal to or higher than the second predetermined value, the control device 200A turns on the decompression devices 131A, 131B, and 131C to operate the separation devices 110A, 110B, and 10C. To.

A gas supply system 100B illustrated in FIG. 6 includes separation devices 110A, 110B, and 110C, bypass lines 161, 162, and 163, cutoff valves 161A, 161B, and 161C, a control device 200B, and a flow meter 201.

  The separation devices 110A, 110B, and 110C are connected in series with each other. In addition, bypass lines 161, 162, and 163 are connected in parallel to the separators 110A, 110B, and 110C, respectively. The bypass lines 161, 162, and 163 are provided with shutoff valves 161A, 162A, and 163A, respectively.

  One flow meter 201 is provided on the downstream side of the separation device 110C, and detects the flow rate of the city gas B output from the separation devices 110A, 110B, and 110C. In FIG. 6, the illustration of the LPG separated by the separation devices 110A, 110B, and 110C is omitted.

  The control device 200B is a computer. The control device 200B operates the separation devices 110A, 110B, and 110C in order based on the flow rate of the city gas B detected by the flow meter 201.

  The gas supply system 100B is a system that can adjust the number of separation devices 110A, 110B, and 100C according to the flow rate of the city gas B by controlling the shutoff valves 161A, 161B, and 161C with the control device 200B.

  When the flow rate of the city gas B detected by the flow meter 201 is less than the first predetermined value, the control device 200B shuts off the shutoff valve 161A and operates the shutoff valve 162A to operate only the separation device 110A. 163A is opened.

  When the flow rate of the city gas B detected by the flow meter 201 is not less than the first predetermined value and less than the second predetermined value, the control device 200B causes the shutoff valves 161A and 162A to operate the separation devices 110A and 100B. Is shut off and the shutoff valve 163A is opened.

  When the flow rate of the city gas B detected by the flow meter 201 is greater than or equal to the second predetermined value, the control device 200B causes the shutoff valves 161A, 162A, and 163A to operate the separation devices 110A, 110B, and 100C. Shut off.

  The gas supply system according to the exemplary embodiment of the present invention has been described above, but the present invention is not limited to the specifically disclosed embodiment, and does not depart from the scope of the claims. Various modifications and changes are possible.

DESCRIPTION OF SYMBOLS 10 LNG base 11A, 11B Tank 12 Calorific value adjustment device 13 Vaporizer 100, 100A, 100B Gas supply system 110 Separation device 120 Pipeline 131 Decompression device 132 Pressure gauge 133 Flow adjustment device 134 Shut-off valve 135 Bypass line 135A Shut-off valve 136 Pressure gauge Flow meter 137
Pressure reducing device 138
139 Check valve 140 Boiler 150 Liquefaction device 151 Pressure gauge 152 Shut-off valve 153 Gas pipe 154 GC
155 Valve 156 Valve 158 Valve 157 Gas pipe 161, 162, 163 Bypass line 161A, 161B, 161C Shut-off valve 170 Hydrogen production device 180 Ethylene / propylene production device 200A, 200B Control device 201 Flow meter

Claims (7)

A gas main for transporting a first city gas including methane gas and a hydrocarbon-based gas having 2 or more carbon atoms;
The first city gas is connected to the gas main, and the hydrocarbon gas having 2 or more carbon atoms and the hydrocarbon gas having 2 or more carbon atoms are separated and removed from the first city gas. A gas supply system including a separator that separates the second city gas.   The gas supply system according to claim 1, further comprising a flow rate adjusting device that is provided between the gas main and the separator and adjusts a flow rate of the first city gas transported by the gas main.   The gas supply system according to claim 1, further comprising a decompression device that is provided between the gas main and the separator and depressurizes the first city gas transported by the gas main. Including a plurality of sets of the decompression device and the separator connected in series with each other;
The plurality of sets of the decompression device and the separator are connected in parallel to the gas main pipe,
Multiple decompressors have different pressure settings after decompression,
4. The gas supply system according to claim 3, wherein the gas supply system operates sequentially from the separator connected in series to a decompression device having a high pressure set value in accordance with an increase in the flow rate of the first city gas. Including a plurality of separators, a plurality of bypass pipes connected in parallel to the plurality of separators, and a plurality of shut-off valves respectively inserted in series in the plurality of bypass pipes,
The plurality of separators are connected in series,
The gas supply system according to any one of claims 1 to 3, wherein the number of the separators to be operated is increased by controlling the opening and closing of the shut-off valve according to an increase in the flow rate of the first city gas.   2. The apparatus further includes a liquefaction device connected to an output port for outputting the hydrocarbon gas having 2 or more carbon atoms of the separator and liquefying the hydrocarbon gas having 2 or more carbon atoms. The gas supply system according to claim 5. The gas supply system according to any one of claims 1 to 6, wherein a vaporizer is connected to a second end portion of the gas main pipe opposite to the first end portion to which the separator is connected.

Images