Natural gas distribution method and natural gas excess pressure power generation skid-mounted equipment

Abstract

The invention discloses a natural gas distribution method and natural gas excess pressure power generation skid-mounted equipment, and relates to the field of energy recovery of a natural gas excess pressure power generation technology. The natural gas distribution method comprises the steps that under the condition that the flow of gas entering a station is smaller than or equal to a first flow threshold value, an original pressure regulating skid is switched on; under the condition that the in-station gas flow is larger than the first flow threshold value and smaller than the second flow threshold value, the expansion machine path is conducted, and the residual pressure power generation module is started; or, the expansion machine path is conducted, the piping skid bypass is conducted, and the residual pressure power generation module is started; and under the condition that the in-station gas flow is larger than or equal to the second flow threshold value and smaller than or equal to the third flow threshold value, the expansion machine path is conducted, the piping skid bypass is conducted, and the residual pressure power generation module is started. And under the condition that the in-station gas flow is larger than the third flow threshold value, the expansion machine path is conducted, the original pressure regulating skid is conducted, and the residual pressure power generation module is started. The natural gas separate transportation method can be suitable for various working conditions.

Description

Technical Field

[0001] This application relates to the field of energy recovery in natural gas waste pressure power generation technology, and more particularly to a natural gas distribution method and a skid-mounted device for natural gas waste pressure power generation. Background Technology

[0002] Before entering the city's gas network, natural gas needs to be depressurized at natural gas pressure regulating stations or gate stations. Traditional depressurization methods often use throttle valves to directly reduce pressure, resulting in a significant loss of pressure energy as heat, leading to energy waste. Therefore, in recent years, natural gas pressure recovery power generation technology has gradually gained attention. Its core lies in using an expander to replace the throttle valve, converting the pressure energy of natural gas into electrical energy. However, existing natural gas pressure recovery power generation systems still have some key issues that need to be addressed. Existing control methods are mostly based on fixed threshold regulation, failing to fully consider system performance under varying operating conditions. Summary of the Invention This application provides a natural gas distribution method and a skid-mounted natural gas residual pressure power generation device, aiming to make the natural gas distribution method applicable to various working conditions.

[0003] This application provides a natural gas distribution method, which includes: When the inlet gas flow rate is less than or equal to a first flow threshold, the original pressure regulating skid is activated. When the inlet gas flow rate is greater than the first flow threshold and less than a second flow threshold, the expander circuit is activated, and the residual pressure power generation module is started; or, the expander circuit is activated, the piping skid bypass is activated, and the residual pressure power generation module is started, wherein the second flow threshold is equal to the full-load gas transmission capacity of the residual pressure power generation module. When the inlet gas flow rate is greater than or equal to the second flow threshold and less than or equal to a third flow threshold, the expander circuit is activated, the piping skid bypass is activated, and the residual pressure power generation module is started, wherein the gas transmission capacity of the expander circuit is less than or equal to the full-load gas transmission capacity of the residual pressure power generation module, and the third flow threshold is greater than the full-load gas transmission capacity of the residual pressure power generation module. When the inlet gas flow rate is greater than the third flow threshold, the expander circuit is activated, the original pressure regulating skid is activated, and the residual pressure power generation module is started.

[0004] This application provides a natural gas station system, which includes a primary pressure regulating skid and a natural gas waste pressure power generation skid-mounted device. The natural gas waste pressure power generation skid-mounted device includes: a first skid base, an expander circuit, a piping skid bypass, and a waste pressure power generation module. The expander circuit, piping skid bypass, and waste pressure power generation module are mounted on the first skid base. The expander circuit, piping skid bypass, and primary pressure regulating skid are connected in parallel. The waste pressure power generation module includes an expander, a gearbox, and a generator.

[0005] This application provides a skid-mounted natural gas residual pressure power generation device, which includes: a first skid, an expander circuit, a piping skid bypass, and a residual pressure power generation module. The expander circuit, the piping skid bypass, and the residual pressure power generation module are mounted on the first skid. The expander circuit, the piping skid bypass, and the original pressure regulating skid are connected in parallel. The residual pressure power generation module includes an expander, a gearbox, and a generator; as well as a lubricating oil module and a dry gas sealing module, all mounted on the first skid.

[0006] This application enables the natural gas station to implement different natural gas distribution methods under different operating conditions, i.e., when the inlet gas flow rate of the natural gas station is in different flow ranges, so that the natural gas distribution method can be applied to a variety of operating conditions. Attached Figure Description

[0007] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0008] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of a skid-mounted natural gas residual pressure power generation device provided in an embodiment of this application; Figure 2 for Figure 1 Top view of the skid-mounted natural gas residual pressure power generation equipment; Figure 3 Another structural schematic diagram of the skid-mounted natural gas residual pressure power generation device provided in the embodiments of this application; Figure 4 A flowchart of a natural gas distribution method provided in an embodiment of this application; Figure 5 This is a flowchart of step S21; Figure 6 This is a flowchart of step S22; Figure 7 This is a flowchart of step S3; Figure 8 This is a flowchart of step S4. Detailed Implementation

[0010] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0011] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0012] Natural gas is typically transported at relatively high pressure over long distances; for example, the pressure can reach 4 MPa to 10 MPa. Before entering the city's gas network, natural gas needs to be depressurized at natural gas pressure regulating stations or city gate stations. These stations can usually reduce the pressure to 0.4 MPa. Here, "natural gas station" refers to either the aforementioned pressure regulating station or city gate station.

[0013] Traditional pressure reduction methods often use throttle valves to directly reduce pressure, resulting in a large amount of natural gas pressure energy being lost as heat, leading to energy waste.

[0014] In related technologies, during the natural gas depressurization process, an expander unit is configured to convert the pressure energy of the natural gas into electrical energy. However, the existing expander control methods are relatively simple and cannot be applied to various working conditions.

[0015] Based on this, this application provides a natural gas station system.

[0016] Figure 1 This is a schematic diagram of the structure of a skid-mounted natural gas residual pressure power generation device provided in an embodiment of this application; Figure 2 for Figure 1 Top view of the skid-mounted natural gas residual pressure power generation equipment; Figure 3 Another structural schematic diagram of the skid-mounted natural gas residual pressure power generation device provided in the embodiments of this application.

[0017] Please see Figure 1 , Figure 2 and Figure 3 The natural gas station system includes: the original pressure regulating skid and the TG-PU skid-mounted equipment for generating natural gas residual pressure.

[0018] The original pressure regulating skid can be an existing distribution pipeline at a natural gas pressure regulating station or natural gas gate station.

[0019] The natural gas residual pressure power generation skid-mounted equipment TG-PU includes: a first skid, an expander circuit NG01, a piping skid bypass circuit NG02, and a residual pressure power generation module TG01. The residual pressure power generation module TG01 is used to convert the pressure energy of natural gas into electrical energy.

[0020] Expander circuit NG01, piping skid bypass NG02 and residual pressure power generation module TG01 are mounted on the first skid. Expander circuit NG01, piping skid bypass NG02 and the original voltage regulating skid are connected in parallel. The residual pressure power generation module TG01 includes expander T01, gearbox GB01 and generator G01.

[0021] For example, expander T01 is installed on expander circuit NG01, gearbox GB01 is connected to expander T01, and generator G01 is connected to gearbox GB01.

[0022] Among them, the expander circuit NG01, the piping skid bypass circuit NG02 and the residual pressure power generation module TG01 can all be set on the first skid. This arrangement can achieve a high degree of equipment integration, reduce the difficulty of transportation and on-site installation, effectively reduce the footprint, and improve the system compactness.

[0023] In addition, the expander circuit NG01, the residual pressure power generation module TG01, and the piping skid bypass NG02 in the natural gas residual pressure power generation skid-mounted equipment TG-PU can be pre-installed on the first skid, and then the natural gas residual pressure power generation skid-mounted equipment TG-PU can be installed in the natural gas station, thereby reducing the complexity of construction.

[0024] In some embodiments, the residual pressure power generation module TG01 further includes a second skid, on which the expander T01, gearbox GB01 and generator G01 are all mounted, and the second skid may be mounted on the first skid.

[0025] For example, the second skid can be mounted on the first skid using fasteners such as bolts.

[0026] Among them, the expander T01, gearbox GB01 and generator G01 can be pre-installed on the second skid, and then the residual pressure power generation module TG01 is installed on the first skid, which can reduce the construction complexity.

[0027] In some examples, the natural gas residual pressure power generation skid-mounted equipment TG-PU may also include a lubricating oil module LOS01 and a dry gas sealing module SGS01, both of which are mounted on the first skid.

[0028] The functionality of the TG-PU skid-mounted natural gas residual pressure power generation equipment can be enhanced by installing a lubricating oil module LOS01 and a dry gas sealing module SGS01 on the first skid.

[0029] Please see Figure 3 In some embodiments, the natural gas residual pressure power generation skid-mounted equipment TG-PU may further include: an air inlet and an air outlet, an expander circuit NG01 connected between the air inlet and the air outlet, and a piping skid bypass NG02 disposed between the air inlet and the air outlet.

[0030] The natural gas residual pressure power generation skid-mounted equipment TG-PU may also include: a check valve CV01, which is located between the expander circuit NG01 and the gas outlet, and between the piping skid bypass NG02 and the gas outlet.

[0031] Fluctuations in downstream users' gas consumption can cause pressure fluctuations in the pipelines of the TG-PU skid-mounted natural gas pressure boosting generator. As a result, the pressure at the outlet of expander T01 will fluctuate, which may lead to natural gas backflow at the outlet of expander T01.

[0032] Specifically, by installing a check valve CV01 downstream of the pressure-generating module TG01, the backflow of natural gas at the outlet of the expander T01 can be reduced, thus mitigating the impact of pressure changes caused by fluctuations in downstream user gas volume on the pressure-generating module TG01. Furthermore, the check valve CV01 is also located downstream of the piping skid bypass NG02, thereby further reducing the impact of pressure changes caused by fluctuations in downstream user gas volume on the piping skid bypass NG02.

[0033] In some examples, the natural gas residual pressure power generation skid-mounted equipment TG-PU may also include a first control device PLC, and the natural gas station system may also include a second control device, which may be located in the control room of the natural gas pressure regulating station or the natural gas gate station.

[0034] In some examples, the first control device PLC may include a control cabinet and a first controller, with the first controller housed within the control cabinet and the control cabinet providing protection for the first controller.

[0035] In some examples, the natural gas residual pressure power generation skid-mounted unit TG-PU may also include a flow meter 130, which may be installed on the expander circuit NG01 and is used to detect the gas flow rate of the expander circuit NG01. The flow meter 130 is connected to a first control device PLC, so that the first control device PLC can obtain the gas flow rate of the expander circuit NG01.

[0036] In some examples, the natural gas residual pressure power generation skid-mounted unit TG-PU may also include flow meter indicators FIQ and FIC, which are used to display the gas flow rate detected by flow meter 130.

[0037] In some examples, the natural gas residual pressure power generation skid-mounted equipment TG-PU may also include a residual pressure power generation skid outlet valve PV02 and an outlet pipe 520. One end of the outlet pipe 520 is connected to the expander circuit NG01 and the piping skid bypass NG02, and the other end of the outlet pipe 520 serves as the outlet. The residual pressure power generation skid outlet valve PV02 can be installed on the outlet pipe 520.

[0038] For example, the outlet valve PV02 of the residual pressure generator skid can be a pressure stabilizing valve.

[0039] In other examples, the natural gas residual pressure power generation skid-mounted unit (TG-PU) may also include a first pressure transmitter, a second pressure transmitter, and a third pressure transmitter. The first pressure transmitter may be located at the gas outlet to detect the pressure at the outlet. The second pressure transmitter may be located on the expander circuit NG01 to detect the pressure on the expander circuit NG01. The third pressure transmitter may be located on the piping skid bypass NG02 to detect the pressure on the piping skid bypass NG02. The first, second, and third pressure transmitters are all connected to a first control device (PLC) and a second control device. The first control device (PLC) and the second control device can monitor the pressure at the gas outlet, the pressure on the expander circuit NG01, and the pressure on the piping skid bypass NG02.

[0040] The first control device PLC and the second control device are connected to the dispatch center. Therefore, the dispatch center and the second control device can also monitor the pressure of the outlet, the pressure of the expander circuit NG01, and the pressure of the piping skid bypass NG02.

[0041] Please see you later. Figure 2 In some embodiments, the natural gas station system may also include an interactive device, which may be located in the control room of the natural gas pressure regulating station or the natural gas gate station. The interactive device is connected to a second control device, and staff can input control commands through the interactive device. The control commands can be sent to the first control device PLC through the second control device, and then the first control device PLC can control the natural gas residual pressure power generation skid-mounted equipment TG-PU and the original pressure regulating skid according to the control commands.

[0042] For example, the interactive device may include a touch display device.

[0043] Please see Figure 3 In some embodiments, the natural gas residual pressure power generation skid-mounted equipment TG-PU may further include: a first valve PV01, which is disposed on the expander circuit NG01, wherein the gas delivery volume of the expander circuit NG01 can be adjusted by adjusting the opening degree of the first valve PV01. For example, the first valve PV01 can be an electric valve or a solenoid valve.

[0044] The first valve PV01 is connected to the first control device PLC and the second control device, so that both the first control device PLC and the second control device can adjust the opening degree of the first valve PV01 and monitor the opening degree of the first valve PV01. In addition, the dispatch center can remotely control the first valve PV01 and monitor the opening degree of the first valve PV01.

[0045] In some examples, the natural gas residual pressure power generation skid-mounted unit TG-PU may also include: a first emergency shut-off valve SSV01, which is located on the expander circuit NG01.

[0046] The first emergency shut-off valve SSV01 is connected to the first control device PLC and the second control device. Both the first control device PLC and the second control device can control the opening or closing of the first emergency shut-off valve SSV01, thereby controlling the conduction or closure of the expander circuit NG01. In addition, the dispatch center can remotely control the first emergency shut-off valve SSV01.

[0047] In the event of an emergency, the first control device PLC or the second control device can control the first emergency shut-off valve SSV01 to quickly close or open, thus preventing an accident from occurring.

[0048] In some embodiments, the natural gas residual pressure power generation skid-mounted unit TG-PU further includes a second valve FV01, which is disposed on the piping skid bypass NG02. The gas supply rate of the piping skid bypass NG02 can be adjusted by adjusting the opening degree of the second valve FV01.

[0049] For example, the second valve FV01 can be an electric valve or a solenoid valve.

[0050] The second valve FV01 is connected to both the first control device (PLC) and the second control device, allowing both to control and monitor the opening degree of the second valve FV01. Furthermore, the dispatch center can remotely control and monitor the opening degree of the second valve FV01.

[0051] In some examples, the natural gas waste pressure power generation skid-mounted unit TG-PU may also include a waste pressure power generation skid inlet valve BV01 and a waste pressure power generation skid outlet valve PV02. Specifically, the waste pressure power generation skid inlet valve BV01 is located at the gas inlet, and the waste pressure power generation skid outlet valve PV02 is located at the gas outlet.

[0052] In some examples, the natural gas station is equipped with skid-external inlet valves and skid-external outlet valves.

[0053] In some examples, the inlet system may also include a third valve, which is mounted on the original pressure regulating skid and may be connected to the second control device and the first control device PLC. The first control device (PLC) or the second control device can control the opening degree of the third valve and monitor its opening degree. Furthermore, the dispatch center can remotely control the third valve and monitor its opening degree.

[0054] Among them, the control of the first valve PV01, the second valve FV01, the third valve, and the first emergency shut-off valve SSV01 is controlled by either the first control device PLC or the second control device. At any given time, one of the first control device PLC and the second control device controls the above-mentioned multiple valves. That is to say, the first control device PLC and the second control device do not control the same valve at the same time. The control rights of the first control device PLC and the second control device over the valves are interlocked and unique, thereby avoiding conflicts between the control rights of the first control device PLC and the second control device over the valves.

[0055] This application provides a natural gas distribution method, which is used in the natural gas station system provided in some of the above embodiments.

[0056] Figure 4 A flowchart of a natural gas distribution method provided in an embodiment of this application.

[0057] Please see Figure 4 The natural gas distribution method may include the following steps S1 to S4.

[0058] S1. When the inlet gas flow rate is less than or equal to the first flow rate threshold, the original pressure regulating skid is turned on.

[0059] The inlet gas flow rate can be the total flow rate of the natural gas station.

[0060] For example, the first flow threshold is equal to the start-up flow of the residual pressure generation module TG01.

[0061] If the inlet gas flow rate is less than or equal to the first flow rate threshold, the inlet gas flow rate is too low and does not reach the residual pressure power generation module TG01 (e.g. Figure 3 The starting flow rate is shown in the figure. At this time, the expander circuit NG01 is closed, and the natural gas is distributed by the original pressure regulating skid.

[0062] At this time, the second valve FV01 on the bypass NG02 of the piping skid remains in hot standby mode.

[0063] The natural gas distribution method may also include the following step S2.

[0064] S2. When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is opened and the residual pressure power generation module is started; or, the expander circuit is opened, the piping skid bypass is opened, and the residual pressure power generation module is started, wherein the second flow rate threshold is equal to the full-load gas delivery of the residual pressure power generation module.

[0065] Specifically, when the inlet gas flow rate is greater than the first flow rate threshold but less than the second flow rate threshold, the inlet gas flow rate reaches the start-up flow rate of the residual pressure power generation module TG01. The start-up flow rate of expander T01 is less than the full-load gas delivery capacity of expander circuit NG01.

[0066] In step S2, the pressure-generating module TG01 is activated, converting the pressure energy of natural gas into electrical energy, thereby reducing energy waste. Specifically, the expander T01 converts the pressure energy of natural gas into mechanical energy, while the generator G01 converts the mechanical energy into electrical energy. For example, the generator G01 can be connected to the power grid for power supply.

[0067] Step S2 may include either step S21 or step S22.

[0068] S21. When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is opened and the residual pressure power generation module is started.

[0069] In step S21, the gas delivery volume of expander circuit NG01 is equal to the inlet gas flow rate, and the inlet gas flow rate is greater than the start-up flow rate of expander T01.

[0070] In step S21, only the expander circuit NG01 is opened. At this time, all the natural gas enters the waste pressure power generation module TG01 to perform work. Therefore, the waste pressure power generation module TG01 has a high power and generates a large amount of electricity, thereby reducing energy waste.

[0071] Figure 5 This is a flowchart of step S21.

[0072] Please see Figure 5 In some embodiments, step S21 includes steps S211 to S214.

[0073] S211, the original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the gas flow rate at the inlet.

[0074] S212, the bypass of the piping skid is opened, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass of the piping skid is equal to the gas flow rate at the station, and the original pressure regulating skid is closed.

[0075] In step S212, the gas flow rate at the station is monitored to meet the start-up conditions of the expander T01. In step S212, the skid inlet valve, skid outlet valve, and residual pressure generator skid inlet valve BV01 and residual pressure generator skid outlet valve PV02 are opened in sequence.

[0076] Subsequently, open the second valve FV01 on the bypass NG02 of the piping skid, and gradually close the third valve on the original pressure regulating skid to reduce the gas flow rate of the original pressure regulating skid; simultaneously, gradually increase the opening of the second valve FV01 on the bypass NG02 of the piping skid, so that the gas flow rate of the bypass NG02 of the piping skid gradually increases. This continues until the bypass NG02 of the piping skid replaces the original pressure regulating skid to complete all incoming gas distribution, the third valve on the original pressure regulating skid is completely closed, and the opening of the second valve FV01 on the bypass NG02 of the piping skid remains unchanged. During the adjustment process, it is necessary to ensure that the total downstream gas flow rate remains stable.

[0077] S213, Expander circuit is connected, residual pressure power generation module starts.

[0078] In step S213, the emergency shut-off valve SSV01 at the inlet of the expander circuit NG01 is opened, the residual pressure power generation module TG01 is started, and the first valve PV01 on the expander circuit NG01 is opened.

[0079] S214. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit equals the inlet gas flow rate, and then close the piping skid bypass.

[0080] In step S214, the first valve PV01 on the expander circuit NG01 is gradually opened to increase the gas delivery volume of the expander circuit NG01, while the second valve FV01 on the piping skid bypass NG02 is gradually closed to decrease the gas delivery volume of the piping skid bypass NG02. During this adjustment process, the total gas delivery flow of the natural gas waste pressure power generation skid-mounted equipment TG-PU remains constant. After confirming that the waste pressure power generation module is operating correctly at low flow rates, the opening of the first valve PV01 is further increased, while the opening of the second valve FV01 is gradually decreased until all incoming gas is distributed through the expander circuit NG01, and the waste pressure power generation module TG01 is operating stably. At this point, the second valve FV01 is completely closed, and the opening of the first valve PV01 remains unchanged. At this time, the gas delivery volume of the expander circuit NG01 equals the inlet gas flow rate. This adjustment process must still maintain a stable total gas delivery flow rate of the waste pressure power generation unit.

[0081] If the inlet gas flow rate is greater than the first flow rate threshold but less than the second flow rate threshold, the following step S22 can also be performed.

[0082] S22. When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is opened, the piping skid bypass is opened, and the residual pressure power generation module is started.

[0083] In step S22, both the expander circuit NG01 and the piping skid bypass TG01 are connected. At this time, a portion of the natural gas enters the pressure relief power generation module TG01 to generate electricity, and the piping skid bypass TG01 can also distribute some natural gas. If the pressure relief power generation module TG01 shuts down in an emergency or malfunctions, it can reduce fluctuations in downstream natural gas flow.

[0084] Figure 6 This is a flowchart of step S22.

[0085] Please see Figure 6 Step S22 may include the following steps S221 to S225.

[0086] S221, the original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the gas flow rate at the inlet.

[0087] S222, the bypass of the piping skid is turned on, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass of the piping skid is equal to the first preset gas supply, and the gas supply of the original pressure regulating skid is equal to the difference between the inlet gas flow rate and the first preset gas supply, wherein the first preset gas supply is less than the inlet gas flow rate.

[0088] In step S222, the gas flow rate at the station is monitored to meet the start-up conditions of the expander T01. In step S222, the skid inlet valve, skid outlet valve, and residual pressure generator skid inlet valve BV01 and residual pressure generator skid outlet valve PV02 are opened in sequence.

[0089] Subsequently, open the second valve FV01 on the bypass NG02 of the piping skid and gradually close the third valve to reduce the gas distribution volume of the original pressure regulating skid; simultaneously, gradually increase the opening of the second valve FV01 on the bypass NG02 of the piping skid to gradually increase the gas distribution volume of the bypass NG02 of the piping skid. During this adjustment process, it is necessary to ensure that the total downstream gas distribution volume remains stable until the flow rate of the bypass NG02 of the piping skid is increased to the first preset gas distribution volume, at which point the opening of the third valve in the original pressure regulating skid remains unchanged. At this point, the gas distribution volume of the original pressure regulating skid is maintained at the difference between the inlet gas flow rate and the first preset gas distribution volume. The first preset gas distribution volume is less than the inlet gas flow rate and is greater than or equal to the start-up flow rate of the expander T01.

[0090] S223, Expander circuit is connected, residual pressure power generation module starts.

[0091] In step S223, first open the emergency shut-off valve SSV01 at the inlet of the expander circuit NG01, then gradually open the first valve PV01 on the inlet expander circuit NG01, and at the same time open the residual pressure power generation module TG01.

[0092] S224. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit equals the first preset gas delivery volume, and then close the piping skid bypass.

[0093] In step S224, the second valve FV01 is gradually closed to reduce the gas flow rate of the piping skid bypass NG02, while the opening of the first valve PV01 is gradually increased to increase the gas flow rate of the expander circuit NG01. During the adjustment process, the total gas flow rate of the natural gas residual pressure power generation skid-mounted equipment TG-PU remains constant.

[0094] After confirming that the TG01 residual pressure power generation module is operating correctly under low flow conditions, continue to reduce the opening of the second valve FV01 and increase the opening of the first valve PV01 until the gas delivery volume of the expander circuit NG01 is equal to the first preset gas delivery volume, and the expander T01 reaches the operating condition and runs stably. Then, the second valve FV01 is completely closed so that the bypass NG02 of the piping skid is closed. At the same time, the opening of the first valve PV01 remains unchanged. During the adjustment process, the total gas delivery flow of the TG-PU skid-mounted natural gas residual pressure power generation equipment must be kept stable.

[0095] S225, the bypass of the piping skid is turned on, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass of the piping skid is equal to the difference between the inlet gas flow rate and the first preset gas supply, and the original pressure regulating skid is turned off.

[0096] In step S225, the second valve FV01 on the bypass NG02 of the piping skid is opened, and the opening degree of the second valve FV01 is gradually increased to increase the gas supply of the bypass NG02 of the piping skid. At the same time, the opening degree of the third valve in the original pressure regulating skid is gradually decreased to reduce the gas supply of the original pressure regulating skid, until the bypass NG02 of the piping skid replaces the original pressure regulating skid to continue to distribute the remaining gas volume, the third valve is completely closed, and the gas supply of the bypass NG02 of the piping skid is equal to the difference between the inlet gas flow rate and the first preset gas supply volume.

[0097] Please see you later. Figure 4 The natural gas distribution method may also include the following step S3.

[0098] S3. When the gas flow rate at the station is greater than or equal to the second flow threshold and less than or equal to the third flow threshold, the expander circuit is opened, the piping skid bypass is opened, and the residual pressure power generation module is started. The gas delivery volume of the expander circuit is less than or equal to the full-load gas delivery volume of the residual pressure power generation module, and the third flow threshold is greater than the full-load gas delivery volume of the residual pressure power generation module.

[0099] In step S3, when the inlet gas flow rate is greater than or equal to the second flow rate threshold and less than or equal to the third flow rate threshold, the residual pressure power generation module TG01 can convert the pressure energy of natural gas into electrical energy, thereby reducing energy waste. Furthermore, the gas delivery volume of the expander circuit NG01 can be less than or equal to the full-load gas delivery volume of the residual pressure power generation module TG01, thereby preventing the residual pressure power generation module TG01 from being overloaded.

[0100] Figure 7 This is a flowchart of step S3.

[0101] Please see Figure 7 In some embodiments, step S3 may include steps S31 to S35 as described below.

[0102] S31, the original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the gas flow rate at the inlet.

[0103] S32. The bypass of the piping skid is turned on, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid until the gas supply of the bypass of the piping skid is equal to the second preset gas supply, wherein the second preset gas supply is less than the gas flow rate at the station and the second preset gas supply is less than or equal to the full-load gas supply of the residual pressure power generation module.

[0104] S33, Expander circuit is connected, residual pressure power generation module starts.

[0105] S34. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit is equal to the second preset gas delivery volume, and then close the piping skid bypass.

[0106] In step S34, the residual pressure power generation module TG01 can be in full-load operation. At this time, the second preset gas transmission volume can be equal to the full-load gas transmission volume of the residual pressure power generation module TG01.

[0107] The waste pressure power generation module TG01 can be in a state of not being fully loaded. At this time, the second preset gas transmission volume can be less than the full-load gas transmission volume of the waste pressure power generation module TG01.

[0108] S35. The bypass of the piping skid is opened, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid until the gas supply of the bypass of the piping skid is equal to the difference between the inlet gas flow rate and the second preset gas supply, and the original pressure regulating skid is closed.

[0109] The natural gas distribution method may also include the following step S4.

[0110] S4. When the inlet gas flow rate is greater than the third flow rate threshold, the expander circuit is activated, the original pressure regulating skid is activated, and the residual pressure power generation module is started.

[0111] In step S4, when the inlet gas flow rate exceeds the third flow threshold, the expander circuit NG01 and the original pressure regulating skid are connected. At this time, the residual pressure power generation module TG01 can convert the pressure energy of natural gas into electrical energy, thereby increasing power generation and reducing energy waste. Furthermore, the original pressure regulating skid can also be connected. Therefore, in the event of an emergency shutdown or malfunction of the residual pressure power generation module TG01, the original pressure regulating skid can continue to distribute natural gas, thereby reducing downstream flow fluctuations.

[0112] In addition, when the inlet gas flow rate is greater than the third flow threshold, the expander circuit NG01 and the original pressure regulating skid are connected, which can reduce the number of connected pipes, simplify the control process, and facilitate control.

[0113] Figure 8 This is a flowchart of step S4.

[0114] Please see Figure 8 In some embodiments, step S4 may include the following steps S41 to S44.

[0115] S41, the original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the gas flow rate at the inlet.

[0116] S42. The bypass of the piping skid is turned on, increasing the gas supply of the bypass of the piping skid and decreasing the gas supply of the original pressure regulating skid until the gas supply of the bypass of the piping skid is equal to the second preset gas supply, wherein the second preset gas supply is less than the gas flow rate at the station and the second preset gas supply is less than or equal to the full-load gas supply of the residual pressure power generation module.

[0117] S43, Expander circuit is connected, residual pressure power generation module starts.

[0118] S44. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit is equal to the second preset gas delivery volume, the gas delivery volume of the original pressure regulating skid is equal to the difference between the inlet gas flow rate and the second preset gas delivery volume, and the piping skid bypass is closed.

[0119] In step S44, the opening of the first valve PV01 is gradually increased to increase the gas delivery volume of the expander circuit NG01, while the second valve FV01 is gradually closed to decrease the gas delivery volume of the piping skid bypass NG02. During the adjustment process, the total gas delivery flow of the residual pressure generator skid remains constant. After confirming that the expander unit is operating correctly at low flow rates, the opening of the first valve PV01 is further increased, and the opening of the second valve FV01 is gradually decreased until the gas delivery volume of the expander circuit equals the second preset gas delivery volume. At this point, the second valve FV01 is completely closed, and the opening of the first valve PV01 remains unchanged. Meanwhile, the opening of the third valve in the original pressure regulating skid remains unchanged, and the remaining gas continues to be delivered. At this point, the gas delivery volume of the original pressure regulating skid is equal to the difference between the inlet gas flow rate and the second preset gas delivery volume.

[0120] In step S44, the residual pressure power generation module TG01 can be in a full-load operation state or in a non-full-load operation state.

[0121] In the natural gas distribution method provided in this application embodiment, the natural gas station executes different distribution methods when the natural gas station is under different operating conditions, that is, when the inlet gas flow rate of the natural gas station is in different flow ranges, so that the natural gas distribution method can be applied to a variety of operating conditions.

[0122] In some embodiments, when the inlet gas flow rate is greater than the third flow rate threshold, the expander circuit NG01 and the original pressure regulating skid are connected, and the ratio of the gas delivery volume of the expander circuit NG01 to the gas delivery volume of the original pressure regulating skid is a first preset ratio.

[0123] In some examples, in the event of a failure of the residual pressure generator module TG01, the original pressure regulating skid conductor takes over the gas transmission volume of the expander circuit NG01, thereby ensuring the stability of gas transmission in the natural gas station system.

[0124] The gas consumption of downstream users may fluctuate, which will cause pressure fluctuations in the gas pipeline and thus affect the stability of gas consumption for downstream users.

[0125] The natural gas distribution method provided in this application embodiment may further include the following steps S5 and S6.

[0126] S5. When the pressure deviation at the outlet of the natural gas residual pressure power generation skid-mounted equipment is greater than the first pressure threshold, the pressure value of the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment is adjusted based on the first adjustment value so that the actual pressure value at the outlet is close to the target pressure range, wherein the pressure deviation is equal to the difference between the actual pressure value and the target pressure range. S6. When the pressure deviation is less than or equal to the first pressure threshold, adjust the pressure value of the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment based on the second adjustment value so that the actual pressure value of the gas outlet is within the target pressure range, wherein the second adjustment value is less than the first adjustment value.

[0127] When the gas consumption in the downstream pipeline fluctuates, the actual pressure value at the outlet of the natural gas residual pressure power generation skid-mounted equipment will deviate from the target pressure range. This means that the actual pressure value is not within the target pressure range. In this case, the actual pressure value may be greater than the maximum value of the target pressure range or less than the minimum value of the target pressure range.

[0128] When the pressure deviation at the outlet of the natural gas residual pressure power generation skid-mounted equipment exceeds the first pressure threshold, the pressure value of the currently connected pipeline in the TG-PU of the natural gas residual pressure power generation skid-mounted equipment can be adjusted once or multiple times to bring the actual pressure value at the outlet closer to the target pressure range. The pressure value adjusted each time is the first adjustment value, which is relatively large, so that the actual pressure value at the outlet can quickly approach the target pressure range.

[0129] When the pressure deviation is less than or equal to the first pressure threshold, the pressure value of the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment TG-PU can be adjusted once or multiple times to ensure that the actual pressure value of the outlet is within the target pressure range. The pressure value adjusted each time is the second adjustment value, which is less than the first adjustment value, thereby achieving fine adjustment of the actual pressure value of the outlet.

[0130] Where the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment TG-PU may include expander line NG01, or the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment TG-PU may include expander line NG01 and piping skid bypass line NG02.

[0131] When the inlet gas flow rate is greater than or equal to the second flow rate threshold and less than or equal to the third flow rate threshold, the currently connected pipelines in the natural gas residual pressure power generation skid-mounted equipment TG-PU may include expander line NG01 and piping skid bypass line NG02.

[0132] When the inlet gas flow rate is greater than the third flow rate threshold, the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment TG-PU may include the expander circuit NG01.

[0133] For example, the pressure value of the currently connected pipeline can be adjusted by changing the opening degree of the valve set on the currently connected pipeline.

[0134] When the actual pressure value of the downstream pipeline deviates from the target pressure range, adjusting the pressure at the outlet can bring the actual pressure value of the downstream pipeline within the standard pressure range, thereby ensuring the stability of the outlet pressure of the TG-PU skid-mounted natural gas residual pressure power generation equipment and improving the stability of gas supply for users.

[0135] Furthermore, when the pressure deviation is greater than the first pressure threshold, the pressure value at the outlet is adjusted based on the first adjustment value; when the pressure deviation is less than the first pressure threshold, the pressure value at the outlet is adjusted based on the second adjustment value. This avoids the pressure value at the outlet from exceeding the target pressure range during the adjustment process.

[0136] For example, the first pressure threshold can be 0.1 MPa.

[0137] In some examples, the pressure value at the outlet can be adjusted using a PID (proportional-integral-derivative algorithm). The PID algorithm uses incremental adjustment and is combined with an anti-windup mechanism to prevent control failure caused by the accumulation of deviations over a long period of time.

[0138] When the pressure deviation at the outlet of the TG-PU skid-mounted natural gas residual pressure power generation equipment exceeds the first pressure threshold, the fuzzy adaptive PID algorithm, i.e., the fine adjustment algorithm, can be used to adjust the pressure value at the outlet.

[0139] When the pressure deviation at the outlet of the TG-PU skid-mounted natural gas residual pressure power generation equipment is less than the first pressure threshold, the conventional PID algorithm, namely the fast target value approximation algorithm, can be used to adjust the pressure value at the outlet.

[0140] In some embodiments, the actual pressure value at the outlet is adjusted to be lower than a preset value. This setting prevents the pressure value at the outlet from exceeding the preset value, thereby achieving over-pressure control at the outlet.

[0141] In the process of adjusting the outlet pressure using the fuzzy adaptive PID algorithm, the pressure is adjusted through derivative-first, setpoint filtering, and conditional integration. Derivative-first refers to differentiating only the feedback signal (not the error) to avoid impact on the derivative term when the setpoint changes abruptly. Setpoint filtering applies a first-order low-pass filter to the setpoint to smooth the step input. Conditional integration activates the integral term only under specific conditions (such as small error or unsaturated output) to avoid integral saturation.

[0142] Both the first control device PLC and the second control device can be configured to control the first valve PV01, the second valve FV01, the third valve, and the first emergency shut-off valve SSV01 so that the natural gas station system can perform the steps in the above-mentioned natural gas distribution method.

[0143] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0144] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A natural gas distribution method for a natural gas station system, the natural gas station system comprising: A natural gas waste pressure power generation skid-mounted equipment and a primary pressure regulating skid, wherein the natural gas waste pressure power generation skid-mounted equipment includes an expander circuit, a piping skid bypass, and a waste pressure power generation module, wherein the expander circuit, the piping skid bypass, and the primary pressure regulating skid are connected in parallel, and the waste pressure power generation module is disposed on the expander circuit, characterized in that it includes: When the inlet gas flow rate is less than or equal to the first flow rate threshold, the original pressure regulating skid is turned on; When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is activated and the residual pressure power generation module is started; or, when the expander circuit is activated and the piping skid bypass is activated, the residual pressure power generation module is started, wherein the second flow rate threshold is equal to the full-load gas delivery capacity of the residual pressure power generation module. When the inlet gas flow rate is greater than or equal to the second flow rate threshold and less than or equal to the third flow rate threshold, the expander circuit is activated, the piping skid bypass is activated, and the residual pressure power generation module is started, wherein the gas delivery volume of the expander circuit is less than or equal to the full-load gas delivery volume of the residual pressure power generation module, and the third flow rate threshold is greater than the full-load gas delivery volume of the residual pressure power generation module. When the inlet gas flow rate is greater than the third flow rate threshold, the expander circuit is activated, the original pressure regulating skid is activated, and the residual pressure power generation module is started.

2. The natural gas distribution method according to claim 1, characterized in that, When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is activated and the residual pressure power generation module is started, including: The original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the inlet gas flow rate; The bypass of the piping skid is turned on, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the inlet gas flow rate, and the original pressure regulating skid is turned off. When the expander circuit is connected, the residual pressure power generation module is started. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit equals the inlet gas flow rate, then close the piping skid bypass.

3. The natural gas distribution method according to claim 1, characterized in that, When the inlet gas flow rate is greater than the first flow rate threshold and less than the second flow rate threshold, the expander circuit is activated, the piping skid bypass is activated, and the residual pressure power generation module is started, including: The original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the inlet gas flow rate; The bypass of the piping skid is activated, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the first preset gas supply. The gas supply of the original pressure regulating skid is equal to the difference between the inlet gas flow rate and the first preset gas supply, wherein the first preset gas supply is less than the inlet gas flow rate. When the expander circuit is connected, the residual pressure power generation module is started. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit is equal to the first preset gas delivery volume, and then close the piping skid bypass. The bypass of the piping skid is activated, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the difference between the inlet gas flow rate and the first preset gas supply, at which point the original pressure regulating skid is closed.

4. The natural gas distribution method according to claim 1, characterized in that, When the inlet gas flow rate is greater than or equal to the second flow rate threshold and less than or equal to the third flow rate threshold, the expander circuit is activated, the piping skid bypass is activated, and the residual pressure power generation module is started, including: The original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the inlet gas flow rate; The bypass of the piping skid is turned on, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the second preset gas supply, wherein the second preset gas supply is less than the inlet gas flow rate and the second preset gas supply is less than or equal to the full-load gas supply of the residual pressure power generation module. When the expander circuit is connected, the residual pressure power generation module is started. Increase the gas delivery rate of the expander circuit and decrease the gas delivery rate of the piping skid bypass until the gas delivery rate of the expander circuit is equal to the second preset gas delivery rate, and then close the piping skid bypass. The bypass of the piping skid is activated, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the difference between the inlet gas flow rate and the second preset gas supply, at which point the original pressure regulating skid is closed.

5. The natural gas distribution method according to claim 1, characterized in that, When the inlet gas flow rate exceeds the third flow threshold, the expander circuit is activated, the original pressure regulating skid is activated, and the residual pressure power generation module is started, including: The original pressure regulating skid is turned on, and the gas delivery volume of the original pressure regulating skid is equal to the inlet gas flow rate; The bypass of the piping skid is turned on, increasing the gas supply of the bypass and decreasing the gas supply of the original pressure regulating skid, until the gas supply of the bypass is equal to the second preset gas supply, wherein the second preset gas supply is less than the inlet gas flow rate and the second preset gas supply is less than or equal to the full-load gas supply of the residual pressure power generation module. When the expander circuit is connected, the residual pressure power generation module is started. Increase the gas delivery volume of the expander circuit and decrease the gas delivery volume of the piping skid bypass until the gas delivery volume of the expander circuit is equal to the second preset gas delivery volume, the gas delivery volume of the original pressure regulating skid is equal to the difference between the inlet gas flow rate and the second preset gas delivery volume, and the piping skid bypass is closed.

6. The natural gas distribution method according to any one of claims 1-5, characterized in that, Also includes: When the expander circuit and the original pressure regulating skid are connected, the ratio of the gas delivery volume of the expander circuit to the gas delivery volume of the original pressure regulating skid is a first preset ratio.

7. The natural gas distribution method according to claim 6, used in a natural gas station system, wherein the natural gas residual pressure power generation skid-mounted equipment of the natural gas station system further includes an inlet and an outlet, the expander circuit is connected between the inlet and the outlet, and the piping skid bypass is connected between the inlet and the outlet, characterized in that, Also includes: When the pressure deviation at the outlet of the natural gas residual pressure power generation skid-mounted equipment is greater than a first pressure threshold, the pressure value of the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment is adjusted based on a first adjustment value so that the actual pressure value at the outlet is close to the target pressure range, wherein the pressure deviation is equal to the difference between the actual pressure value and the target pressure range. When the pressure deviation is less than or equal to the first pressure threshold, the pressure value of the currently connected pipeline in the natural gas residual pressure power generation skid-mounted equipment is adjusted based on the second adjustment value so that the actual pressure value of the gas outlet is within the target pressure range, wherein the second adjustment value is less than the first adjustment value.

8. A natural gas station system for performing the steps of the natural gas distribution method as described in any one of claims 1-7, characterized in that, include: Original pressure skid; A natural gas residual pressure power generation skid-mounted device includes: a first skid, an expander circuit, a piping skid bypass, and a residual pressure power generation module. The expander circuit, the piping skid bypass, and the residual pressure power generation module are mounted on the first skid. The expander circuit, the piping skid bypass, and the original pressure regulating skid are connected in parallel. The residual pressure power generation module includes an expander, a gearbox, and a generator.

9. A skid-mounted natural gas residual pressure power generation device, used to perform the steps of the natural gas distribution method as described in any one of claims 1-7, characterized in that, include: The first skid, the expander circuit, the piping skid bypass, and the residual pressure power generation module are arranged on the first skid. The expander circuit, the piping skid bypass, and the residual pressure power generation module are connected in parallel. The residual pressure power generation module includes an expander, a gearbox, and a generator. Both the lubricating oil module and the dry gas seal module are mounted on the first skid.

10. The skid-mounted natural gas residual pressure power generation equipment according to claim 9, characterized in that, Also includes: An air inlet and an air outlet are provided, the expander circuit is connected between the air inlet and the air outlet, and the piping skid bypass is provided between the air inlet and the air outlet; A check valve is provided between the expander circuit and the outlet, and between the piping skid bypass and the outlet.

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