JP2016035254A - Decompression energy recovery device in gas pipeline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to continue stable supply of gas while a secondary pressure of a governor is free from the influence of energy recovery, and to ensure setting of a temperature of the gas decompressed in an expansion turbine and returned to a secondary pipeline to be not less than a set temperature (0°C).SOLUTION: A decompression energy recovery device 1 comprises: an expansion turbine 10; a first gas line 11 connecting a primary pipeline P1 to an inlet of the expansion turbine 10; a second gas line 12 connecting an outlet of the expansion turbine 10 to a secondary pipeline P2; and a cold recovery heat exchanger portion 13 recovering cold of gas the temperature of which falls by energy recovery by the expansion turbine 10. A back pressure regulating valve 14 is provided downstream of the cold recovery heat exchanger portion 13 in the second gas line 12 for detecting the gas temperature and regulating a back pressure of the expansion turbine 10, and the gas temperature in the second gas line 12 is set to be not less than a set temperature (for example, 0°C) by regulating the back pressure by the back pressure regulating valve 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a decompression energy recovery apparatus that recovers decompression energy of a gas pipeline including a governor using an expansion turbine.

  In a gas supply system using a pipeline, it is common to reduce high-pressure gas to multi-stage medium-pressure gas using a governor (pressure regulator) installed in the pipeline, and to reduce pressure to the low-pressure gas at the most downstream and supply it to the customer. Is. The governor provided in the pipeline is for reducing the pressure (primary pressure) of the upstream (primary) pipeline to the pressure (secondary pressure) of the downstream (secondary) pipeline. Depressurization from the primary pressure to the secondary pressure results in a loss of pressure energy.

  On the other hand, an apparatus is known in which the primary pressure in the governor is reduced by an expansion turbine, and energy lost at the time of pressure reduction is recovered as power generation or cold use (see Patent Document 1 below). In this prior art, an expansion turbine and a governor are provided in parallel to reduce the primary pressure to the secondary pressure, and the expansion turbine is rotationally driven when the gas from the primary pipeline expands, and uses the decompression loss energy as power. As a result, power is generated, and when the flow limit of the expansion turbine is exceeded during operation of the expansion turbine, the governor is opened so that the excess amount flows into the secondary pipeline.

  In addition, this prior art is provided with pre-heating means and post-heating means for heating the gas by heat exchange on the upstream side and downstream side of the expansion turbine. The energy is recovered from the expansion turbine with high efficiency by raising the temperature in advance with the heating means, and the cold heat is recovered from the gas that has become low temperature by the expansion turbine using the post-heating means, and is effectively used for cooling or the like. . The preheating means here is supplied with warm water heated by using the exhaust heat of a relatively low temperature heat source such as exhaust heat from a cogeneration system or factory exhaust heat.

JP 7-217800 A

  When the gas pressure of the primary pipeline in the governor is reduced by the expansion turbine and returned to the secondary pipeline, the temperature of the gas to be returned to the secondary pipeline is required to be 0 ° C. or more as an essential requirement. It has been. In addition, when energy recovery is performed by an expansion turbine, it is required that the secondary pressure of the governor can be continuously supplied without being affected by energy recovery.

  At this time, if the gas whose temperature has been lowered due to the energy recovery of the expansion turbine can be heated with sufficient cold demand, it can meet the demand of returning the gas temperature to 0 ° C. or higher and returning it to the secondary pipeline. However, when the demand for cold heat is low, the gas temperature on the outlet side of the expansion turbine cannot be sufficiently heated, and there arises a problem that such a request cannot be met.

For this, as in the prior art, it is conceivable to provide preheating means upstream of the expansion turbine to preheat the gas entering the expansion turbine. However, when exhaust heat from a cogeneration system or factory exhaust heat is used for such preheating means, there is a problem that a stable heat supply cannot be received, and a combustion boiler or the like is used for this preheating means. In this case, energy is consumed by the operation of the expansion turbine that recovers energy, which not only reduces the energy saving effect but also reduces the CO ₂ generation suppressing effect. In addition, the temperature adjustment of the gas to be returned to the secondary pipeline depends on the pre-heating means on the upstream side of the expansion turbine, and there is a problem that it is difficult to adjust the temperature with good responsiveness when the load of the expansion turbine changes. .

  In addition, when the primary pressure is reduced by the expansion turbine and returned to the secondary pipeline of the governor, if the gas flow rate in the primary pipeline suddenly changes or the primary pressure rises, the response of the expansion turbine alone The pressure cannot be adjusted properly. For this reason, there arises a problem that the delivery pressure to the secondary pipeline cannot be quickly controlled to a specified pressure.

  In addition, when the cold heat of the gas whose temperature has been lowered by the energy recovery of the expansion turbine is recovered and effectively used by the post-heating means, the gas whose temperature has been lowered by the post-heating means cannot be sufficiently heated if the cold demand is small. The problem of freezing the cold recovery circulating water of the post-heating means arises. It is required to recover the energy by the expansion turbine while suppressing the heating of the gas by the preheating means to the minimum necessary and avoiding the freezing of the cold recovery circulating water in the postheating means.

  This invention makes it an example of a subject to cope with such a problem. That is, in an apparatus that recovers the decompression energy of the governor in the gas pipeline by the expansion turbine, the secondary pressure of the governor is not affected by the energy recovery, enabling stable gas supply to be continued, and the decompression by the expansion turbine. Ensure that the temperature of the gas returned to the secondary pipeline is 0 ° C or higher, control the temperature and pressure of the gas returned to the secondary pipeline to the specified values, and reduce the temperature by recovering the energy of the expansion turbine When recovering the cold heat of the used gas and effectively using it, the heating of the gas entering the expansion turbine can be kept to the minimum necessary, and the expansion turbine can be operated sufficiently while avoiding freezing of the cold heat recovery circulating water, etc. Is the object of the present invention.

  In order to achieve such an object, a reduced pressure energy recovery apparatus in a gas pipeline according to the present invention has the following configuration.

  In a decompression energy recovery device for recovering decompression energy of a gas pipeline including a governor, an expansion turbine, a first gas line connecting a primary pipeline upstream of a governor and an inlet of the expansion turbine, an outlet of the expansion turbine, and a governor A second gas line connecting downstream secondary pipelines, and a heat recovery unit for recovering cold heat that is provided in the second gas line and recovers cold heat of the gas whose temperature has been lowered by energy recovery by the expansion turbine, A back pressure adjusting valve that detects one or both of the gas temperature and the back pressure of the expansion turbine and adjusts the throttle is provided on the downstream side of the cold heat recovery heat exchanger in the second gas line, and the gas temperature or the In the gas pipeline, the back pressure regulating valve is controlled so as to increase the back pressure when the back pressure decreases. Vacuum energy recovery devices.

  A back pressure adjustment valve that adjusts the throttle by detecting one or both of the gas temperature and the back pressure of the expansion turbine is provided on the downstream side of the heat exchanger for cooling heat recovery in the second gas line to reduce the gas temperature or back pressure. Since the back pressure adjustment valve is controlled to increase the back pressure in the case of low temperature, the temperature of the gas returned to the secondary pipeline by making adjustments to the back pressure adjustment valve is surely kept at 0 ° C or higher even when the cold demand is low can do. In addition, since the fluctuation of the back pressure of the expansion turbine can be absorbed by the control of the back pressure adjustment valve, the gas pressure returned to the secondary side pipeline can be stabilized, without being affected by energy recovery, A stable gas supply can be continued.

It is explanatory drawing which showed one structural example of the pressure reduction energy recovery apparatus in the gas pipeline which concerns on embodiment of this invention. It is explanatory drawing which showed the other structural example of the pressure reduction energy recovery apparatus in the gas pipeline which concerns on embodiment of this invention. It is explanatory drawing which showed the other structural example of the pressure reduction energy recovery apparatus in the gas pipeline which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration example of a decompression energy recovery device in a gas pipeline according to an embodiment of the present invention. The decompression energy recovery apparatus 1 according to the embodiment of the present invention is provided alongside a gas pipeline constituting a gas supply system, and recovers the decompression energy of the governor G as motive power or power generation.

  The decompression energy recovery apparatus 1 includes an expansion turbine 10, a first gas line 11 connecting the primary pipeline P <b> 1 upstream of the governor G and the inlet of the expansion turbine 10, an outlet of the expansion turbine 10, and a secondary pipe downstream of the governor G. A second gas line 12 connecting the line P2 and a cold heat recovery heat exchanging unit 13 that is provided in the second gas line 12 and recovers the cold heat of the gas whose temperature is lowered by the energy recovery by the expansion turbine 10 are provided.

  The expansion turbine 10 is rotationally driven when the gas from the primary pipeline P1 expands and depressurizes, and collects the depressurized energy as power to generate power. The energy recovered by the expansion turbine 10 is defined by the pressure difference between the inlet and the outlet. When the inlet of the expansion turbine 10 is directly connected to the primary pipeline P1 and the outlet is directly connected to the secondary pipeline P2. The energy defined by the pressure difference between the primary pressure and the secondary pressure is recovered by the expansion turbine 10.

  The 1st gas line 11 and the 2nd gas line 12 are comprised by the gas pipe of the arbitrary diameter below the diameter of the primary side pipeline P1 or the secondary side pipeline P2. The first gas line 11 and the second gas line 12 can be configured by connecting a plurality of gas pipes, and a valve, a filter, or the like can be interposed in the middle as needed.

  The expansion turbine 10 reduces the temperature of gas with energy recovery. The heat recovery unit 13 for recovering cold heat raises the gas temperature by heat exchange with the gas whose temperature has decreased in the second gas line 12 and simultaneously supplies cold to the cold demand customer C. The heat recovery unit 13 for cold heat recovery is provided with a circulation channel 13A through which the circulating water for cold energy recovery flows. The circulating water flowing through the circulation channel 13A and the hot water circulating through the cold demand destination are the heat exchange unit 13B. Exchange heat.

  In addition to such a configuration, the reduced pressure energy recovery device 1 according to the embodiment of the present invention includes a back pressure adjusting valve 14, a gas temperature detecting means 15, and a back pressure detecting means 16 in the second gas line 12. . The back pressure adjustment valve 14 is provided on the downstream side of the cold heat recovery heat exchange section 13 in the second gas line 12. The back pressure adjusting valve 14 detects the gas temperature downstream of the heat recovery unit 13 for recovering cold heat in the second gas line 12 with the gas temperature detecting means 15, and the back pressure of the expansion turbine 10 in the second gas line 12. Is detected by the back pressure detecting means 16 and the back pressure adjusting valve 14 is adjusted so that the gas temperature detected by the gas temperature detecting means 15 does not become lower than a set temperature (for example, 0 ° C.).

  According to the decompression energy recovery apparatus 1 having such a configuration, when the demand of the cold demand customer C is low and the temperature of the gas flowing through the second gas line 12 cannot be sufficiently increased, the back pressure regulating valve 14 The operation of the expansion turbine 10 is suppressed by controlling in the direction of narrowing. As a result, the amount of energy recovered by the expansion turbine 10 is reduced, and a decrease in gas temperature is suppressed. When such back pressure adjustment of the expansion turbine 10 is performed, the amount of power generated by the expansion turbine 10 inevitably decreases. Here, the power generation output due to the operation of the expansion turbine 10 is auxiliary power supply, and priority is given to stabilizing the secondary pressure of the secondary pipeline P2.

  Further, even when the back pressure of the expansion turbine 10 rises due to a load fluctuation of the expansion turbine 10 or the like, the gas pressure returned to the secondary pipeline P2 is controlled to a proper value by controlling the back pressure regulating valve 14 to be throttled. By controlling the back pressure adjustment valve 14 as described above, the temperature of the gas returned to the secondary pipeline P2 can be surely set to 0 ° C. or more, and the gas pressure returned to the secondary pipeline P2 can be stabilized. And stable gas supply can be realized while maintaining stable operation of the governor G.

  In addition, when the cooling load is suddenly changed, the gas temperature changing thereby is directly detected, and the work amount of the expansion turbine 10 directly connected to the decrease in the gas temperature is controlled by adjusting the back pressure adjustment valve 14, It becomes possible to control the gas temperature with high responsiveness.

  FIG. 2 is an explanatory view showing another configuration example of the decompression energy recovery apparatus in the gas pipeline according to the embodiment of the present invention. Parts common to the description in FIG. 1 described above are denoted by the same reference numerals, and redundant description is omitted. In the reduced pressure energy recovery apparatus 1 (1A) according to this configuration example, a configuration for controlling the amount of gas flowing into the expansion turbine 10 is added to the example shown in FIG.

  Specifically, a gas flow rate detection means 17 for detecting a gas flow rate is provided in the first gas line 11, and the throttle of the inlet valve 10V provided at the inlet of the expansion turbine 10 is controlled by the detected flow rate of the gas flow rate detection means 17. . Here, first, the inlet valve control unit 18 controls the inlet valve 10V by the detected flow rate of the gas flow rate detection means 17, and the inlet valve 10V is controlled so as to suppress the gas inflow amount to the expansion turbine 10 when the detected flow rate increases. Control to narrow down.

  In the configuration example shown in FIG. 1, when there is a large amount of cold demand and the gas temperature of the second gas line 12 can be sufficiently increased, the back pressure regulating valve 14 is opened and the back pressure of the expansion turbine 10 is controlled by the governor G. The expansion turbine 10 can be operated with a secondary pressure of In such a situation, if a sudden change in the gas flow rate in the primary pipeline P1 or a rise in the primary pressure occurs, the gas pressure in the second gas line 12 can be controlled only by controlling the recovery energy of the expansion turbine 10 alone. It is difficult to quickly stabilize (back pressure of the expansion turbine 10).

  In order to cope with such a situation, the configuration example shown in FIG. 2 is provided with the gas flow rate detecting means 17 for detecting the gas flow rate in the first gas line 11, and the gas flow rate detecting means 17 at the inlet of the expansion turbine 10. An inlet valve 10V is provided that suppresses the amount of gas flowing into the expansion turbine 10 when the detected flow rate is increased. According to such a configuration, the gas flow rate to the expansion turbine 10 can be quickly suppressed with respect to the increase in the gas flow rate of the first gas line 11, and the gas pressure fluctuations of the second gas line 12 can be stabilized.

  Feedback control by back pressure detection means 16 provided in the second gas line 12 can be further added to the control of the inlet valve 10V. In this case, the inlet valve control unit 18 performs control based on the detected back pressure of the back pressure detecting means 16 in addition to the control based on the detected flow rate of the gas flow rate detecting means 17, and throttles the inlet valve 10V when the detected back pressure increases. Thus, the amount of gas flowing into the expansion turbine 10 is suppressed. Here, the back pressure detecting means 16 is installed on the upstream side of the back pressure regulating valve 14 in the second gas line 12. As described above, the gas pressure in the second gas line 12 is controlled by feeding back the gas pressure fluctuation in the second gas line 12 (back pressure fluctuation in the expansion turbine 10) and controlling the amount of gas flowing into the expansion turbine 10. Can be.

  The inlet valve control unit 18 can independently control the inlet valve 10V based on the detected flow rate of the gas flow rate detecting means 17 and the inlet valve 10V based on the detected pressure of the back pressure detecting means 16. When fluctuations in the gas flow rate and gas pressure in the first gas line 11 are relatively small, the pressure in the second gas line 12 can be stabilized by such single control.

  The example shown in FIG. 2 shows an example in which the control of the inlet valve 10V is added to the configuration for controlling the operation of the expansion turbine 10 by adjusting the back pressure adjusting valve 14, but the control of the back pressure adjusting valve 14 is omitted. In addition, the control of the inlet valve 10V can be performed independently. When the demand of the cold energy customer C is high and the gas temperature in the second gas line 12 can always be maintained at 0 ° C. or higher, the control of the back pressure adjusting valve 14 by the gas temperature is omitted and the second control is performed only by controlling the inlet valve 10V. The gas pressure in the gas line 12 can be stabilized.

  FIG. 3 is an explanatory view showing another configuration example of the decompression energy recovery device in the gas pipeline according to the embodiment of the present invention. The parts common to the description in FIG. 1 and FIG. 2 described above are denoted by the same reference numerals, and redundant description is omitted. In the reduced pressure energy recovery apparatus 1 (1B) according to this configuration example, the configuration related to prevention of freezing of circulating water in the heat exchange unit 13 for cold energy recovery is added to the example shown in FIG.

  In this example, a preheating heat exchanging unit 20 that preheats the gas flowing into the expansion turbine 10 is provided in the first gas line 11. The preheating heat exchanging unit 20 increases the gas temperature through heat exchange with the gas flowing through the first gas line 11. The preheating heat exchange unit 20 includes a circulation channel 20A through which preheating circulation water flows, and the circulating water flowing through the circulation channel 20A and the hot water circulating through the heat source H are heated by the heat exchange unit 20B. Exchange. The heat source H here can utilize exhaust heat from a cogeneration system, factory exhaust heat, or the like.

  The circulation flow path 20A of the preheating heat exchange section 20 and the circulation flow path 13A of the cold heat recovery heat exchange section 13 are heat-exchanged by the circulating water heat exchange section 21, and the preheating heat exchange section 20 The circulating water of the heat exchanger 13 for collecting cold heat is heated by the heat source H. According to this, even when the temperature of the gas flowing into the expansion turbine 10 is low in winter or the like, the temperature of the flowing gas is raised by the heating of the heat exchanger 20 for preheating, so that the energy recovery amount of the expansion turbine 10 is increased to some extent. While ensuring, the fall of the gas temperature of the 2nd gas line 12 can be suppressed.

  Further, even when the energy recovery amount of the expansion turbine 10 is increased and the outlet gas temperature of the expansion turbine 10 becomes low, the circulating water in the heat recovery unit 13 for cold heat recovery is frozen by the heat from the circulating water heat exchange unit 21. Can be prevented. Thus, the cold heat can be collected smoothly by the cold heat collecting heat exchanging unit 13. Furthermore, the heat exchange capacity (heat transfer area) of the preheating heat exchange section 20 can be minimized because the heating capacity of the cold heat recovery heat exchange section 13 can be increased by adopting the circulating water heat exchange section 21. It becomes possible to limit to the limit. In addition, by providing the circulating water heat exchanger 21, the expansion turbine 10 can be configured to send the heat from the heat source H to the cold recovery heat exchanger 13 even when there is no or little cold load of the cold demand customer C. Can be rated. For this reason, the operation rate of the expansion turbine 10 improves.

  In the configuration example shown in FIG. 3, when the gas flow rate and gas pressure of the first gas line 11 are stable, the configuration for controlling the inlet valve 10V and the inlet valve 10V can be omitted. Further, the gas temperature of the second gas line 12 is constantly set by heating the gas by the preheating heat exchanging unit 20 or exchanging heat between the circulating water of the preheating heat exchanging unit 20 and the circulating water of the cold heat recovery heat exchanging unit 13. In the case where the temperature can be raised to 0 ° C. or higher, the configuration for controlling the back pressure adjusting valve 14 by detecting the gas temperature or detecting the back pressure can be omitted.

  The gas flow rate and gas pressure of the first gas line 11 are stable, the heating of the gas by the preheating heat exchanger 20 and the circulating water of the preheating heat exchanger 20 and the circulating water of the cold heat recovery heat exchanger 13 are performed. When the gas temperature of the second gas line 12 can be constantly raised to 0 ° C. or higher by heat exchange with the gas, the configuration for controlling the inlet valve 10V and the inlet valve 10V and the detection of the gas temperature and the back pressure are used. Both of the configurations for controlling the back pressure regulating valve 14 can be omitted.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. In addition, the above-described embodiments can be combined by utilizing each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1, 1A, 1B: Depressurized energy recovery device,
10: expansion turbine, 10V: inlet valve,
11: 1st gas line, 12: 2nd gas line,
13: heat exchange part for cold energy recovery, 13A: circulation channel, 13B: heat exchange part,
14: Back pressure adjusting valve, 15: Gas temperature detecting means, 16: Back pressure detecting means,
17: Gas flow rate detection means, 18: Inlet valve control unit,
20: Preheating heat exchange section, 20A: Circulation flow path, 20B: Heat exchange section,
21: Heat exchanger between circulating water,
P1: Primary pipeline, P2: Secondary pipeline, G: Governor,
C: Customer for cold energy, H: Heat source

Claims (3)

In a decompression energy recovery device that recovers decompression energy of a gas pipeline equipped with a governor,
An expansion turbine, a first gas line connecting a primary pipeline upstream of a governor and an inlet of the expansion turbine, a second gas line connecting an outlet of the expansion turbine and a secondary pipeline downstream of the governor, and the second A heat exchange part for recovering cold energy, which is provided in the gas line and recovers the cold energy of the gas whose temperature is lowered by the energy recovery by the expansion turbine,
A back pressure adjusting valve that detects the gas temperature and adjusts the back pressure of the expansion turbine is provided on the downstream side of the cold heat recovery heat exchanger in the second gas line,
An apparatus for recovering reduced pressure energy in a gas pipeline, wherein a gas temperature in the second gas line is set to a set temperature or higher by back pressure adjustment by the back pressure adjustment valve. Providing a preheating heat exchange section for preheating the gas flowing into the expansion turbine in the first gas line;
2. The reduced pressure energy recovery apparatus for a gas pipeline according to claim 1, wherein the circulating water of the cold heat recovery heat exchanger is heated by a heat source of the preheating heat exchanger.   3. The gas pipeline according to claim 2, wherein a heat exchanger between the circulating water for exchanging heat between the circulating water of the preheating heat exchanger and the circulating water of the cold recovery heat exchanger is provided. Depressurized energy recovery device.

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