A control system for a micro gas turbine generator wellhead shale gas supply device

Abstract

The present invention discloses a control system for a shale gas supply device at the wellhead of a micro gas turbine generator. The control and protection system includes a particle droplet control system, a temperature control system, a pressure control system, a liquid level control system, a water hydrocarbon dew point control system, a fine processing control system and a system safety protection system, and the control and protection systems are independently arranged in parallel. The operating parameter signal acquisition system transmits the acquisition signal to the logic judgment command system, and the logic judgment command system is respectively connected to the parameter setting system, the control and protection system and the data storage and remote transmission system. The micro gas turbine power generation system is respectively connected to the parameter setting system, the control and protection system and the data storage and remote transmission system. Beneficial effects: stable control of the water hydrocarbon dew point is achieved to ensure the normal and stable operation of the micro gas turbine; accurate control of sewage discharge is performed according to the fluctuation of the actual operating conditions, and the overall operating cost is reduced; automatic liquid discharge is achieved under different operating condition fluctuations, and the risk of machine tripping and gas cross-talk is reduced.

Description

Technical Field

[0001] The invention relates to the field of shale gas, and in particular to a control system for a shale gas supply device at a wellhead of a micro gas turbine generator. Background Art

[0002] During the shale gas fracturing process, multiple sets of high-power electrical equipment are required to work continuously, but most gas wells are located in remote areas, and the surrounding power grid facilities cannot guarantee the power supply needs of the electrical equipment required for the fracturing process. Conventional diesel generator sets need to be equipped with a large amount of diesel, and the cost and freight are very high. If shale gas gas turbine generator sets are used, the fuel can be obtained locally, the footprint is small, and it has a greater cost advantage.

[0003] At present, the existing micro gas turbine gas supply control system is generally used for pipeline gas and liquefied natural gas, and cannot be applied to wellhead shale gas. This is because the operating conditions of shale gas wells fluctuate more, and the water hydrocarbon dew point of shale gas is different under different operating conditions. The micro gas turbine can only work normally when the water hydrocarbon dew point of shale gas is within a safe range. However, the target operating condition variation range of the existing system is small, and it is not controlled according to the actual operating condition fluctuation value, but a fixed dew point is directly determined according to the cooling temperature of the system, so it cannot adapt to the shale gas operating condition fluctuation range and the requirements for normal and stable operation of the gas turbine; at the same time, the liquid level control of the existing system is difficult to adapt to the operating condition variation range of shale gas wells. For example, most of the systems use water valves, which automatically discharge when there is liquid and automatically close after draining. Once the steam trap is selected, the reliability of automatic closing is related to the operating parameters of the gas, but the shale gas pressure and flow variation range is large. When there may be other pressure changes in a large range, the steam trap cannot be closed in time or reliably. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a control system for a shale gas supply device at the wellhead of a micro gas turbine generator, which can achieve stable control of the water hydrocarbon dew point and automatic drainage under fluctuating operating conditions, reduce the risks of machine tripping and gas cross-talk, ensure the normal and stable operation of the micro gas turbine, and reduce the overall operating cost, thereby providing a stable power supply for various electrical equipment in shale gas fracturing operations.

[0005] The object of the present invention is achieved by the following technical measures: A control system for a micro gas turbine generator wellhead shale gas supply device, comprising an operating parameter signal acquisition system (1), a parameter setting system (2), a logic judgment command system (3), a data storage and remote transmission system (4), and a control and protection system (5) and a micro gas turbine power generation system (13), wherein the control and protection system (5) comprises a particle droplet control system (6), a temperature control system (7), a pressure control system (8), a liquid level control system (9), a water hydrocarbon dew point control system (10), a fine treatment control system (11) and a system safety protection system (12), and the control and protection systems are independently arranged in parallel with each other, the water hydrocarbon dew point control system (10) is used to determine the dew point values ​​of different working conditions and realize stable control of the water hydrocarbon dew point under working condition fluctuations, the liquid level control system (9) is used to realize automatic sewage discharge under working condition fluctuations, the fine treatment control system (11) is used to realize accurate sewage discharge of the liquid level control system (9) and prevent the continuous precipitation of water hydrocarbons in shale gas outgassing, the working condition parameter signal acquisition system (1) transmits the acquisition signal to the logic judgment command system (3), the logic judgment command system (3) is respectively connected to the parameter setting system (2), the control and protection system (5) and the data storage and remote transmission system (4), and the micro gas turbine power generation system (13) is respectively connected to the parameter setting system (2), the control and protection system (5) and the data storage and remote transmission system (4). Connected to the data storage and remote transmission system (4).

[0006] Furthermore, the water hydrocarbon dew point control system (10) comprises a refrigeration unit, a cooler, a coolant bypass valve, a pipeline and pipeline accessories, wherein the refrigeration unit is used to realize the condensation of water vapor and heavy hydrocarbons in the shale gas, the cooler is used to realize the heat exchange between the coolant and the shale gas, and the cooler coolant bypass valve is used to adjust the flow rate of the cooler coolant.

[0007] Furthermore, the fine processing control system (11) comprises a differential pressure transmitter, a temperature compensation sensor, a flow meter, a cable and cable accessories; the flow meter is used to obtain the actual flow value of shale gas; the differential pressure transmitter and the temperature compensation sensor are used to calibrate the flow meter.

[0008] Furthermore, the liquid level control system (9) comprises a liquid level detection element, an automatic sewage discharge valve, a manual sewage discharge valve, a one-way valve, a separator and a sewage discharge pipe, wherein the manual sewage discharge valve and the automatic sewage discharge valve are arranged in parallel for sewage discharge, and the liquid level detection element is used to realize real-time monitoring of the liquid level value.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: the water hydrocarbon dew point value under different operating conditions is controlled by the water hydrocarbon dew point determination system, so that water vapor and heavy hydrocarbons can be condensed and precipitated when the operating conditions fluctuate, and the water hydrocarbon dew point can be stably controlled, so as to meet the requirements of the micro gas turbine for the water hydrocarbon dew point of shale gas and ensure the normal and stable operation of the micro gas turbine; the fine treatment control system can accurately control the discharge of pollutants according to the fluctuation of the actual operating conditions, and prevent the continuous precipitation of water hydrocarbons in the shale gas outlet, while reducing the overall operating cost; the liquid level control system can realize automatic discharge under different operating condition fluctuations, and reduce the risk of machine tripping and gas cross-talk.

[0010] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a scheme diagram of the control system of the micro gas turbine generator wellhead shale gas supply device.

[0012] The numbers in the attached drawings are: 1. Operating parameter signal acquisition system, 2. Parameter setting system, 3. Logical judgment command system, 4. Data storage and remote transmission system, 5. Control and protection system, 6. Particle droplet control system, 7. Temperature control system, 8. Pressure control system, 9. Liquid level control system, 10. Water hydrocarbon dew point control system, 11. Fine treatment control system, 12. System safety protection system, 13. Micro gas turbine power generation system. DETAILED DESCRIPTION

[0013] like Figure 1 As shown, a control system for a micro gas turbine generator wellhead shale gas supply device includes an operating parameter signal acquisition system 1, a parameter setting system 2, a logic judgment command system 3, a data storage remote transmission system 4, a control and protection system 5 and a micro gas turbine power generation system 13, wherein the control and protection system 5 It includes a particle droplet control system 6, a temperature control system 7, a pressure control system 8, a liquid level control system 9, a water hydrocarbon dew point control system 10, a fine treatment control system 11 and a system safety protection system 12, and they are independently arranged in parallel. The water hydrocarbon dew point control system 10 is used to determine the dew point value of different working conditions to achieve stable control of the water hydrocarbon dew point under fluctuating working conditions. The liquid level control system 9 is used to achieve automatic sewage discharge under fluctuating working conditions. The fine treatment control system 11 is used to achieve accurate sewage discharge of the liquid level control system 9 and prevent the continuous precipitation of water hydrocarbons in shale gas outgassing. The working condition parameter signal acquisition system 1 transmits the acquisition signal to the logic judgment command system 3, and the logic judgment command system 3 is respectively connected to the parameter setting system 2, the control protection system 5 and the data storage and remote transmission system 4. The micro gas turbine power generation system 13 is respectively connected to the parameter setting system 2, the control protection system 5 and the data storage and remote transmission system 4.

[0014] The operating parameter signal acquisition system 1 includes a temperature detection element, a pressure detection element, a flow detection element, a pressure difference detection element, a liquid level detection element, a signal cable and a pressure root valve. The operating parameter signal acquisition system 1 detects the temperature through the temperature detection element and transmits it to the logic judgment command system through the signal cable. Similarly, the flow detection element, the pressure difference detection element, and the liquid level detection element transmit the detected flow, pressure difference, and liquid level signals to the logic judgment command system 3.

[0015] The parameter setting system 2 includes a signal input component, a transmission cable and a storage component. The parameter setting system 2 provides an input interface and a human-computer interaction interface for manual or automatic input of control programs and set values, and transmits them to the logic judgment command system 3 via a cable. At the same time, the parameter setting system 2 has a built-in parameter setting range to meet the automatic acquisition of parameters under different working conditions.

[0016] Digital signals of key parameters such as intake pressure, temperature, rotation speed, vibration value, etc. of the micro gas turbine power generation system 13 are transmitted through the interface in the parameter setting system.

[0017] The logic judgment command system 3 includes a logic control unit, an I / O input / output unit, a power supply and an instruction storage unit to meet the judgment of different parameters.

[0018] The data storage and remote transmission system 4 includes a storage unit, a transmission unit, a data conversion unit and a display unit, which can meet the real-time display, retrieval and analysis of parameters during the operation of a single or multiple micro gas turbine generator wellhead shale gas supply devices, so as to realize remote scheduling decisions, remote emergency shutdown, etc.

[0019] The particle droplet control system 6 includes a particle droplet filtering unit, an inspection and cleaning unit and a pipeline unit. The particle droplet filtering unit is used to remove most of the particles and droplets larger than 10um in shale gas. The inspection and cleaning unit is used to regularly inspect and clean the removal efficiency to ensure that it is stable at more than 99-99.9%, thereby meeting the gas turbine's control over the content and size of particles and droplets.

[0020] The temperature control system 7 includes a heating unit and a cooling unit. The cooling unit uses a refrigerator and the heating unit uses an electric heater. The temperature control system 7 is used to meet the temperature requirements of the gas turbine intake air. Optionally, the cooling unit can use a cold dryer and the heating unit can use hot water / steam / water jacket furnace heating.

[0021] The pressure control system 8 includes a pressure regulating valve, a pressure taking pipe and a root valve to meet the gas turbine's requirements for intake pressure.

[0022] The water hydrocarbon dew point control system 10 includes a refrigeration unit, a cooler, an insulation component, a circulating water pump, a gas-liquid separator, a cooler refrigerant inlet and outlet valves, a cooler natural gas inlet valve and a cooler refrigerant bypass valve, pipelines and pipeline accessories. The refrigeration unit is used to realize the condensation of water vapor and heavy hydrocarbons in shale gas, the cooler is used to realize heat exchange between the refrigerant and the shale gas, and the cooler refrigerant bypass valve is used to adjust the flow rate of the cooler refrigerant to adapt to the working conditions of shale gas flow rate changes in a wider range. Through early prediction means, such as test wells, the shale gas inlet temperature variation range, flow variation range, pressure variation range, component variation range and water content variation range are obtained, and then the highest and lowest values ​​of the dew point are determined, and n intermediate values ​​(n≥0) are determined by interpolation method, and finally the theoretical dew point values ​​under different working conditions are obtained: the highest value, the lowest value, the intermediate value 1...intermediate value n (n≥0). The logic judgment system 3 stores the dew point theoretical value and its corresponding shale gas inlet temperature, flow and pressure in the shale gas parameter group of the parameter setting system 2, and at the same time determines the refrigerant flow and the refrigerant temperature at the cooler inlet corresponding to different dew point theoretical values ​​and stores them in the shale gas parameter group of the parameter setting system 2; the parameter setting system 2 has built-in shale gas components, and the operator can also obtain real-time shale gas components through the gas chromatograph, and store the real-time shale gas components in the shale gas parameter group of the parameter setting system 2; the logic judgment command system 3 determines the shale gas inlet temperature, flow and pressure of the shale gas according to the shale gas components transmitted by the parameter setting system 2 and the operating condition parameter signal acquisition system 1. Gas temperature, pressure and flow rate, select the closest set of values ​​in the shale gas parameter group of the parameter setting system 2, and use the refrigerant flow rate and the refrigerant temperature at the cooler inlet as the current target values, and control the refrigeration unit according to the required refrigerant temperature at the cooler inlet; the operating parameter signal acquisition system 1 is provided with a temperature detection element at the cooler inlet, which detects the actual temperature of the refrigerant at the cooler inlet in real time and converts it into an electrical signal to the logic judgment command system 3, and the parameter setting system 2 is also provided with an allowable temperature deviation range. If the deviation between the temperature detected by the operating parameter signal acquisition system 1 and the target value exceeds the allowable temperature deviation range, the logic judgment command system 3 issues an adjustment instruction, and the operator adjusts the opening of the cooler refrigerant bypass valve until the requirements are met, so as to achieve continuous stability of the outlet temperature of the refrigeration unit under different working conditions, so that water vapor and heavy hydrocarbons can be condensed and precipitated when the working conditions fluctuate, thereby achieving stable control of the water hydrocarbon dew point, meeting the requirements of the micro gas turbine for the shale gas water hydrocarbon dew point, and ensuring the normal and stable operation of the micro gas turbine. Optionally, the refrigeration unit can be replaced by a cold dryer; the refrigerant flow rate can be automatically controlled, and the refrigerant inlet and outlet valves of the cooler can be replaced with electric or pneumatic regulating valves.

[0023] The liquid level control system 9 includes a liquid level detection element, an automatic sewage valve, a manual sewage valve, a one-way valve, a separator and a sewage pipe. The manual sewage valve is connected in parallel with the automatic sewage valve for sewage discharge. The liquid level detection element is used to realize real-time monitoring of the liquid level value; the lowest liquid level value under different working conditions is determined according to the shale gas inlet temperature variation range, flow variation range and pressure variation range obtained by the previous prediction method, and the lowest liquid level value under different working conditions is stored in the parameter setting system 2. At the same time, the high-high shutdown value, high alarm value, high adjustment value, low adjustment value, low alarm value and low-low shutdown value of the liquid level are set and stored in the parameter setting system 2; the working condition parameter signal acquisition system 1 realizes The shale gas inlet temperature, flow rate and pressure are detected and converted into electrical signals to be transmitted to the logic judgment command system 3. The logic judgment command system 3 retrieves the closest minimum liquid level value in the parameter setting system 2 through the received temperature, flow rate and pressure as the minimum liquid level value allowed under the current working condition, and detects the liquid level in real time through the liquid level detection element of the liquid level control system 9. When the liquid level reaches the high adjustment value, the logic judgment command system 3 issues an instruction to open the automatic sewage valve for sewage discharge. When the liquid level reaches the low adjustment value, the logic judgment command system 3 issues an instruction to close the automatic sewage valve. Shut-off valves are set before and after the automatic sewage valve. When the automatic sewage valve fails, sewage can be discharged through the manual sewage valve. Optionally, the low shutdown value can be set to automatic adjustment, the liquid level detection element can select a magnetic flap or other types of liquid level gauges, and the automatic sewage valve can select a pneumatic switch valve or an axial flow pneumatic switch valve or an electric axial flow switch valve or a pneumatic electric regulating valve.

[0024] The fine processing control system 11 includes a differential pressure transmitter, a temperature compensation sensor, a flow meter, a pressure compensation sensor, a cable and cable accessories. The flow meter is used to obtain the actual flow value of shale gas, and the differential pressure transmitter and the temperature compensation sensor are used to calibrate the flow meter. According to the closest set of values ​​screened out by the logic judgment command system 3 in the shale gas parameter group of the parameter setting system 2, the theoretical dew point value is used as the current dew point value. According to the obtained current dew point value and the flow variation range of shale gas obtained by prediction in the early stage, the sewage discharge amount required by the liquid level control system 9 is obtained. In combination with the diameter of the separator, the diameter of the sewage pipe and the actual flow value of shale gas obtained, the theoretical time range for the automatic sewage valve to be opened is determined and stored in the parameter setting system 2. The flow meter measures the actual shale gas flow within the theoretical time range and stores it in the parameter setting system 2. The logic judgment system 3 calculates the cumulative flow of shale gas before the automatic sewage valve is opened, and converts it into the liquid volume that the separator needs to discharge. Combined with the real-time liquid level, the actual time when the automatic sewage valve needs to be opened is obtained. The actual time obtained is compared with the fixed liquid storage time of the liquid level control system 9, and the smaller value between the two is taken as the optimal opening time of the automatic sewage valve, so as to achieve accurate sewage discharge, further improve the ability to prevent sewage cross-gas, and thus achieve accurate and reliable control of the dew point. According to the current dew point value obtained, the temperature control target value z is obtained by the temperature control target value z=(current dew point value+y)℃ (y≥0, y is the margin required by the gas engine, corresponding to the requirements of the gas engine). The parameter setting system 2 is provided with an allowable temperature deviation range. The logic judgment command system 3 compares the shale gas outlet temperature collected by the operating parameter signal acquisition system 1 with the temperature control target value z to prevent the continuous precipitation of water hydrocarbons in the shale gas outlet: when the collected temperature is lower than the temperature control target value z, the logic judgment command system 3 issues an instruction to turn on the heating unit of the temperature control system 7 to increase the temperature until the temperature reaches the allowable temperature deviation range close to the temperature control target value z; when the collected temperature is higher than the temperature control target value z, the logic judgment command system 3 issues an instruction to turn off the heating unit to save system electricity and reduce the overall operating cost.

[0025] The system safety protection system 12 includes a cut-off valve, a safety relief valve, a pressure relief valve, a manual relief valve, a warning light, a buzzer and pipeline cables. The system safety protection system 12 includes a pressure sub-protection system, and the pressure sub-protection system has three protections: pressure relief valves and manual relief valves are respectively set in the particle droplet control system 6, the fine processing control system 11 and the pressure control system 8 to meet the timely release of pressure at various locations in an emergency, thereby realizing the first pressure protection; the operating parameter signal acquisition system 1 transmits the measuring point pressure to the logic judgment command system 3 through a cable. When the alarm value is reached, an alarm is sounded through an indicator light and a buzzer. The logic judgment command system 3 outputs a signal, and the alarm content is displayed in the human-computer interaction interface of the parameter setting system 2 for the operator to judge and operate, thereby realizing the second pressure protection; when the detection pressure of the operating parameter signal acquisition system 1 reaches the set cut-off pressure, the logic judgment command system 3 issues a command to the cut-off valve to cut off in time, thereby realizing the third pressure protection.

[0026] The technical solution described in the present invention determines the water hydrocarbon dew point value under different operating conditions through a water hydrocarbon dew point control system, realizes the condensation and precipitation of water vapor and heavy hydrocarbons under fluctuating operating conditions, achieves stable control of the water hydrocarbon dew point, meets the requirements of the micro gas turbine for the water hydrocarbon dew point of shale gas, and ensures the normal and stable operation of the micro gas turbine; the fine treatment control system performs precise control of sewage discharge according to the fluctuation of actual operating conditions, and prevents the continuous precipitation of water hydrocarbons in the shale gas outlet, while reducing the overall operating cost; the liquid level control system realizes automatic liquid discharge under different operating condition fluctuations, and reduces the risk of machine tripping and gas cross-talk.

[0027] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A control system for a micro gas turbine generator wellhead shale gas supply device, characterized in that: The invention comprises an operating parameter signal acquisition system (1), a parameter setting system (2), a logic judgment command system (3), a data storage and remote transmission system (4), a control and protection system (5) and a micro gas turbine power generation system (13). The control and protection system (5) comprises a particle droplet control system (6), a temperature control system (7), a pressure control system (8), a liquid level control system (9), a water hydrocarbon dew point control system (10), a fine treatment control system (11) and a system safety protection system (12), and the control and protection system (5) are independently arranged in parallel with each other. The water hydrocarbon dew point control system (10) is used to determine the dew point value of different operating conditions, so as to realize the control of the water hydrocarbon dew point under the fluctuation of the operating conditions. Stable control, the liquid level control system (9) is used to realize automatic sewage discharge under operating condition fluctuations, the fine treatment control system (11) is used to realize accurate sewage discharge of the liquid level control system (9) and prevent the continuous precipitation of water hydrocarbons in the shale gas outgassing, the operating condition parameter signal acquisition system (1) transmits the acquisition signal to the logic judgment command system (3), the logic judgment command system (3) is respectively connected to the parameter setting system (2), the control protection system (5) and the data storage and remote transmission system (4), and the micro gas turbine power generation system (13) is respectively connected to the parameter setting system (2), the control protection system (5) and the data storage and remote transmission system (4); The water hydrocarbon dew point control system (10) comprises a refrigeration unit, a cooler, a coolant bypass valve, a pipeline and pipeline accessories, wherein the refrigeration unit is used to realize the condensation of water vapor and heavy hydrocarbons in the shale gas, the cooler is used to realize the heat exchange between the coolant and the shale gas, and the coolant bypass valve is used to adjust the flow rate of the coolant; The fine processing control system (11) comprises a differential pressure transmitter, a temperature compensation sensor, a flow meter, a cable and cable accessories; the flow meter is used to obtain the actual flow value of shale gas; the differential pressure transmitter and the temperature compensation sensor are used to calibrate the flow meter.

2. The control system of the micro gas turbine generator wellhead shale gas supply device according to claim 1 is characterized in that: The liquid level control system (9) comprises a liquid level detection element, an automatic sewage discharge valve, a manual sewage discharge valve, a one-way valve, a separator and a sewage discharge pipe. The manual sewage discharge valve and the automatic sewage discharge valve are arranged in parallel for sewage discharge. The liquid level detection element is used to realize real-time monitoring of the liquid level value.

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