Natural gas floating differential pressure radial turbine power generation system and control method

Abstract

The application discloses a natural gas gas float type differential pressure radial turbine power generation system and a control method. The natural gas gas float type differential pressure radial turbine power generation system comprises an independent branch, and the independent branch comprises a main branch. A turbine is arranged in the main branch. The main branch is connected with a bypass branch in parallel. A bearing gas branch is connected with the front part of the main branch in parallel. A cooling gas branch is connected with the rear part of the main branch in parallel. A former station branch ball valve BV01 and a former station branch ball valve BV02 are arranged on the two sides of the independent branch respectively. The application further provides a control method of the natural gas gas float type differential pressure radial turbine power generation system. The turbine unit can be automatically operated, so that the natural gas pressure energy can be efficiently and cleanly recovered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas expansion generator, and particularly relates to a natural gas air-floating differential pressure radial turbine power generation system and a control method. BACKGROUND

[0002] Natural gas needs to be depressurized by a pressure regulating station after being transported to a user download point by a pipeline. At present, the pressure regulating station mainly depressurizes through a regulating valve, which wastes a large amount of pressure energy. The pressure energy recovery device that is actually implemented on the market mainly includes a screw machine. However, the screw machine needs to use lubricating oil, and in the actual use process, there are problems of difficult oil-gas separation and low operation efficiency. Therefore, the present application designs a complete system based on the operation mode of the air-floating differential pressure radial turbine generator set, so that the generator set can be automatically operated, and the efficient and clean recovery of the pressure energy of natural gas is realized.

[0003] The natural gas expansion generator set mainly includes three types of screw machines, radial turbines and axial turbines according to the expander. The axial turbine has a large flow rate, which often exceeds the capacity of the natural gas pressure regulating station, and currently, no related system design has been found. The screw machine needs to use lubricating oil, and the lubricating oil and natural gas are mixed to form emulsion, which is difficult to separate. The design mainly still adopts the traditional oil seal and filter system, which is completely different from the present application.

[0004] A natural gas static pressure air-floating bearing two-stage expansion generator and a power generation system are disclosed in the Chinese patent document with the publication number CN111365080A. The natural gas static pressure air-floating bearing two-stage expansion generator includes a casing, a rotor, a stator, a first turbine, a second turbine, a first static pressure air-floating bearing and a second static pressure air-floating bearing. The casing includes a first gas inlet volute flow channel, a second gas inlet volute flow channel and a generator cavity. The first turbine and the second turbine are respectively installed at two ends of the rotor, and the rotor is arranged in the generator cavity. The stator is fixed to the inner wall of the generator cavity. The first turbine is installed at one end of the rotor through the first static pressure air-floating bearing, and the second turbine is installed at the other end of the rotor through the second static pressure air-floating bearing. The first static pressure air-floating bearing and the second static pressure air-floating bearing are supplied with pressure by natural gas and exhaust to an outlet channel. However, the Chinese patent with the publication number CN111365080A does not involve the design of the entire power generation system. SUMMARY

[0005] The present application solves the problem that the current air-floating differential pressure radial turbine generator lacks a related overall system design, and proposes a natural gas air-floating differential pressure radial turbine power generation system and a control method, so that the turbine can be automatically operated, and the efficient and clean recovery of the pressure energy of natural gas is realized.

[0006] In order to achieve the above object, the present application adopts the following technical scheme: a natural gas floating differential pressure radial turbine power generation system, comprising an independent branch, the independent branch comprising a main branch, a turbine being arranged in the main branch, the main branch being connected in parallel with a bypass branch, a bearing gas branch being connected in parallel with the front part of the main branch, and a cooling gas branch being connected in parallel with the rear part of the main branch; the independent branch being provided with a station branch ball valve BV01 and a station branch ball valve BV02 on both sides respectively.

[0007] In the present application, in the whole system, the differential pressure gas supply process arranged in the natural gas station is generally connected in parallel with a separate turbine branch on the traditional gas supply branch or a separate turbine branch is arranged, in the system of the present application, a flow meter F1, an adjusting valve V1 and a turbine form an independent branch, adjusting valves V2 / V3 and flow meters F2 / F3 and P2 / P3 are traditional gas supply branches, on the one hand, the independent branch is compensated and adjusted in pressure and flow, and on the other hand, mainly undertakes the downstream gas supply and transportation task.

[0008] As a preferred, the main branch further comprises a filter separator GF01, the filter separator GF01 is connected in parallel with a differential pressure transmitter PDT01, the filter separator GF01 is connected with a natural gas metering assembly, the other end of the temperature transmitter TT01 is connected with a safety shut-off valve SSV, the other end of the safety shut-off valve SSV is connected with a pressure transmitter PT03, the other end of the pressure transmitter PT03 is connected with a main adjusting valve PV01, the main adjusting valve PV01 is connected in parallel with a main adjusting valve PV02, the other end of the main adjusting valve PV01 is connected with a pressure transmitter PT04, the pressure transmitter PT04 is connected to the inlet side of the turbine, the outlet side of the turbine is connected with a pressure transmitter PT09, the other end of the pressure transmitter PT09 is connected with a temperature transmitter TT03 and a temperature transmitter TT04 connected in series, the other end of the temperature transmitter TT04 is connected with a check valve CHV02, and the other end of the temperature transmitter TT04 is further connected with an electric shut-off valve ZFV.

[0009] In the application, the filter separator GF01 and the differential pressure transmitter PDT01 are arranged at the inlet of the main branch to perform primary filtration, and the other end of the filter separator is provided with a natural gas metering assembly; the other end of the natural gas metering assembly is provided with a safety cut-off valve SSV, which has the functions of remote control and overpressure take-off, and is used for emergency cut-off of the branch; the main regulating valve PV01 and the main regulating valve PV02 are arranged, which have different diameters and are respectively used for coarse and fine adjustment of power, the pressure transmitter PT03 and the pressure transmitter PT04 are arranged on both sides of the main regulating valve and are used for detecting the pressure before and after adjustment, two temperature transmitters are arranged at the outlet of the main branch to take two, which are used for monitoring the outlet gas temperature after the turbine to prevent the gas temperature from being too low; a pressure transmitter PT09 is arranged to monitor the outlet gas pressure; a check valve CHV02 is arranged to avoid backflow of the downstream; an electric cut-off valve ZFV is arranged to be used for safety relief of the branch.

[0010] Preferably, the natural gas metering assembly comprises a flow meter FIQ01, one end of the flow meter FIQ01 is connected with a pressure transmitter PT01, and the other end of the flow meter FIQ01 is connected with a temperature transmitter TT01.

[0011] In the application, the natural gas metering assembly is arranged to be used for metering of the independent branch natural gas and flow adjustment of the main regulating valve PV01.

[0012] Preferably, one end of the bypass branch is connected to the other end of the safety cut-off valve SSV, the other end of the bypass branch is connected to the other end of the temperature transmitter TT04, and the bypass branch comprises a pneumatic ball valve AOV for pressure relief.

[0013] In the application, the pneumatic ball valve AOV is used to relieve the pressure of the natural gas in the main branch after the safety cut-off valve SSV is closed, so as to prevent the turbine unit from flying.

[0014] Preferably, the bearing gas branch comprises a check valve CHV01, the check valve CHV01 is connected with a buffer tank, the other end of the buffer tank is connected with a high-efficiency filter GF02, the high-efficiency filter GF02 is connected in parallel with a differential pressure transmitter PDT02, the other end of the differential pressure transmitter PDT02 is connected with a regulating valve PV03, the regulating valve PV03 is connected in parallel with a high-frequency solenoid valve SOV, the other end of the regulating valve PV03 is connected with a pressure transmitter PT05 and a pressure transmitter PT06 which are connected in series, and the other end of the pressure transmitter PT06 is connected to the turbine.

[0015] In the application, the high-efficiency filter GF02 and the differential pressure transmitter PDT02 are arranged, and the main function is to perform secondary filtration before the bearing gas is supplied; the buffer tank and the check valve CHV01 are arranged, mainly to ensure the bearing gas required by the air bearing when the turbine falls from the rated speed to the shutdown after the safety shut-off valve SSV is started; the regulating valve PV03 and the high-frequency solenoid valve SOV are arranged in combination, and the regulating valve PV04 on the cooling gas branch is combined, so that the stable supply of the bearing gas and the constant pressure difference between the B port and the C1 port\C2 port of the turbine are ensured by the combination of fast and slow adjustment; the pressure transmitter PT05 and the pressure transmitter PT06 are also arranged, and two of them are taken, and the bearing gas pressure difference is calculated in combination with the two pressure transmitters on the cooling gas branch.

[0016] As preferred, the cooling gas branch includes a flow meter FIQ02, one end of the flow meter FIQ02 is connected with a pressure transmitter PT02, the other end of the flow meter FIQ02 is connected with a temperature transmitter TT02, the other end of the temperature transmitter TT02 is connected with a temperature transmitter TT05, the other end of the temperature transmitter TT05 is connected with a regulating valve PV04, and the other end of the regulating valve PV04 is connected with the other end of the temperature transmitter TT04.

[0017] In the application, the flow meter FIQ02, the regulating valve PV04 and the temperature transmitter TT05 are arranged on the cooling gas branch, which is used to adjust the flow of the expander cooling gas and ensure that the temperature in the cavity is at a constant value, and is also used to compensate the pressure difference of the bearing gas.

[0018] As preferred, the turbine includes a first impeller and a second impeller, and a plurality of air bearing are arranged on the inner side of the middle of the first impeller and the second impeller.

[0019] In the application, the power gas enters and impacts the first-stage impeller from the A port, the gas temperature is reduced after expansion and work, a small part of the gas enters the stator and rotor chamber, is used for cooling the stator, and is discharged from the C1 port and the C2 port, and most of the gas continues to impact the second-stage impeller to work and is discharged into the outlet pipeline from the D port; the B port air supply is used for air bearing work, and at the same time, due to the high pressure in the first-stage and second-stage impeller chambers, the bearing gas enters the stator and rotor chamber and is discharged from the C1 port and the C2 port together with the cooling gas; the working requirement of the air bearing turbine is to maintain the pressure difference between the two ends of the bearing gas in a constant range.

[0020] The application discloses a control method of a natural gas air-floating differential pressure radial turbine power generation system.

[0021] In the application, the power generation power control sets a cascade regulation mode of power-flow-valve position; however, there is an upper threshold for flow regulation, and when the upper threshold is exceeded, flow limiting regulation is performed; the set value of the power has two kinds of power grid AGC and manual setting, and needs to be switched manually; in addition, flow regulation control can be performed independently and is not affected by power regulation.

[0022] Preferably, the bearing gas control comprises: adjusting the error between the differential pressure set value dP.SP and the feedback value dP.FB calculated from the pressure transmitters PT05, PT06, PT07 and PT08, and outputting the valve position value Y to the regulating valve PV03 and the high-frequency electromagnetic valve SOV.

[0023] In the application, the control adopts single-stage mode regulation, and single-stage refers to single differential pressure regulation.

[0024] Preferably, the safety control mainly comprises signal, process control and electrical linkage control.

[0025] In the application, the safety control can improve the safety of the whole system.

[0026] The natural gas air-floating differential pressure radial turbine power generation system and the control method can realize full-automatic operation of the turbine, thereby realizing efficient and clean recovery of natural gas pressure energy; the whole system is automatically regulated, automatically stabilized and automatically operated, and the frequent operation of personnel is reduced; the control quality of the bearing gas is good, the air-floating turbine unit can be applied to various natural gas transmission stations, and the recovery and utilization of natural gas pressure energy are promoted. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Fig. 1 is a turbine structure schematic diagram of the natural gas air-floating differential pressure radial turbine power generation system and the control method;

[0028] Figure 2 Fig. 2 is a system schematic diagram of the natural gas air-floating differential pressure radial turbine power generation system and the control method;

[0029] Figure 3 This is a schematic diagram of an independent branch of a natural gas floating differential pressure radial turbine power generation system and control method of the present application;

[0030] Figure 4 This is a control flow diagram of a natural gas floating differential pressure radial turbine power generation system and control method of the present application;

[0031] Figure 5 This is a schematic diagram of the safety control structure of a natural gas floating differential pressure radial turbine power generation system and control method of the present application;

[0032] Among them, 1, first impeller 2, air bearing 3, stator 4, rotor 5, second impeller. DETAILED DESCRIPTION

[0033] Example:

[0034] This embodiment proposes a natural gas floating differential pressure radial turbine power generation system, referring to Figure 1 、 Figure 2 and Figure 3 , including independent branches, the independent branches include the main branch, the main branch is provided with a turbine, the main branch is connected in parallel with a bypass branch, the front of the main branch is connected in parallel with a bearing gas branch, and the rear of the main branch is connected in parallel with a cooling gas branch; the two sides of the independent branch are respectively provided with the original station branch ball valve BV01 and the original station branch ball valve BV02. In this embodiment, the independent branches can be set in parallel on the traditional gas supply branch. For details, please refer to Figure 2 ; It can also be set up separately; In the present invention, the independent branch is a branch with a turbine; In addition, the original station branch ball valve BV01 and the original station branch ball valve BV02 are used to input and discharge natural gas.

[0035] refer to Figure 3 The main branch also includes a filter separator GF01, which is connected in parallel with a differential pressure transmitter PDT01. The filter separator GF01 is connected to a natural gas metering component. The other end of the temperature transmitter TT01 is connected to a safety shut-off valve SSV. The other end of the safety shut-off valve SSV is connected to a pressure transmitter PT03. The other end of the pressure transmitter PT03 is connected to a main regulating valve PV01. The main regulating valve PV01 is connected in parallel with a main regulating valve PV02. The other end of the main regulating valve PV01 is connected to a pressure transmitter PT04. The pressure transmitter PT04 is connected to the inlet side of the turbine. The outlet side of the turbine is connected to a pressure transmitter PT09. The other end of the pressure transmitter PT09 is connected to the temperature transmitter TT03 and the temperature transmitter TT04 connected in series. The other end of the temperature transmitter TT04 is connected to a check valve CHV02. The other end of the temperature transmitter TT04 is also connected to an electric shut-off valve ZFV.

[0036] Referring to Figure 3 , the natural gas metering assembly comprises a flow meter FIQ01, one end of the flow meter FIQ01 is connected with a pressure transmitter PT01, and the other end of the flow meter FIQ01 is connected with a temperature transmitter TT01. The natural gas metering assembly further comprises a straight pipe section.

[0037] Referring to Figure 3 , one end of the bypass branch is connected to the other end of the safety shut-off valve SSV, and the other end of the bypass branch is connected to the other end of the temperature transmitter TT04, and the bypass branch comprises a pneumatic ball valve AOV for pressure relief.

[0038] Referring to Figure 3 , the bearing gas branch comprises a check valve CHV01, the check valve CHV01 is connected with a buffer tank, the other end of the buffer tank is connected with a high-efficiency filter GF02, the high-efficiency filter GF02 is connected in parallel with a differential pressure transmitter PDT02, the other end of the differential pressure transmitter PDT02 is connected with a regulating valve PV03, the regulating valve PV03 is connected in parallel with a high-frequency solenoid valve SOV, the other end of the regulating valve PV03 is connected with a pressure transmitter PT05 and a pressure transmitter PT06 connected in series, and the other end of the pressure transmitter PT06 is connected to the turbine. In this embodiment, specifically, the other end of the pressure transmitter PT06 is connected with the B port of the turbine, and the check valve CHV01 is connected with the other end of the safety shut-off valve SSV.

[0039] Referring to Figure 3 , the cooling gas branch comprises a flow meter FIQ02, one end of the flow meter FIQ02 is connected with a pressure transmitter PT02, the other end of the flow meter FIQ02 is connected with a temperature transmitter TT02, the other end of the temperature transmitter TT02 is connected with a temperature transmitter TT05, the other end of the temperature transmitter TT05 is connected with a regulating valve PV04, and the other end of the regulating valve PV04 is connected to the other end of the temperature transmitter TT04. In this embodiment, for the pressure transmitter PT02 of the cooling gas branch, the other end thereof is connected with a pressure transmitter PT08, the pressure transmitter PT08 is connected with a C2 port of the turbine, the pressure transmitter PT08 is further connected with a pressure transmitter PT07, and the other end of the pressure transmitter PT07 is connected with a C1 port of the turbine.

[0040] Referring to Figure 1The turbine comprises a first impeller 1 and a second impeller 5, and a plurality of air floating bearings 2 are arranged on the inner side of the middle of the first impeller 1 and the second impeller, and a rotor 4 connected with the air floating bearings 2 is arranged on the outer side of the circumference of the rotor 4, and a plurality of stators 3 are arranged on the outer side of the circumference of the rotor 4. In the embodiment, a temperature sensor is further arranged on the turbine body, which is used for monitoring the temperature of the stator and the rotor chamber; a vibration sensor is arranged on the A port and the D port of the turbine, which is used for monitoring the vibration of the turbine; a rotating speed sensor is arranged on the A port and the D port of the turbine, which is used for monitoring the rotating speed of the turbine; a voltage and current sensor is arranged, which is used for monitoring the power output; the turbine is a high-frequency generator set, and an AC-DC-AC rectification and inversion system is arranged, which is used for realizing the power frequency on-line and limiting the rotating speed of the turbine through the built-in frequency converter.

[0041] In the embodiment, in the differential pressure gas supply process of the natural gas supply station, a separate turbine branch is generally connected in parallel with the traditional gas supply branch or a separate turbine branch is arranged, in the system, a flow meter F1, an adjusting valve V1 and a turbine form an independent branch, adjusting valves V2 / V3 and flow meters F2 / F3 and P2 / P3 are traditional gas supply branches, on the one hand, the independent branch is compensated and adjusted in pressure and flow, and on the other hand, the independent branch mainly undertakes the downstream gas supply and transportation task.

[0042] In the embodiment, a filter separator GF01 and a differential pressure transmitter PDT01 are arranged at the inlet of the main branch, and primary filtration is performed, and a natural gas metering assembly is arranged at the other end of the filter separator; a safety shut-off valve SSV is arranged at the other end of the natural gas metering assembly, which has two functions of remote control and overpressure take-off, and is used for emergency shut-off of the branch; main adjusting valves PV01 and PV02 are arranged, which have different diameters and are used for coarse and fine adjustment of power, pressure transmitters PT03 and PT04 are arranged on the two sides of the main adjusting valve, which are used for detecting the pressure before and after adjustment, two temperature transmitters are arranged at the outlet of the main branch, which are used for monitoring the outlet gas temperature after the turbine, and prevent the gas temperature from being too low; a pressure transmitter PT09 is arranged, which is used for monitoring the outlet gas pressure; a check valve CHV02 is arranged, which avoids backflow of the downstream; an electric shut-off valve ZFV is arranged, which is used for safety relief of the branch.

[0043] In the embodiment, the natural gas metering assembly is arranged, which is used for metering the natural gas of the independent branch and adjusting the flow of the main adjusting valve PV01.

[0044] In the embodiment, the pneumatic ball valve AOV is used for relieving the pressure of the natural gas in the main branch after the safety shut-off valve SSV is closed, and prevents the turbine set from flying.

[0045] In this embodiment, a high-efficiency filter GF02 and a differential pressure transmitter PDT02 are provided, whose main function is to perform secondary filtration on the bearing gas before supply; a buffer tank and a check valve CHV01 are provided, mainly to ensure the bearing gas required for the air-floating bearing when the turbine drops from the rated speed to shutdown after the safety shut-off valve SSV is tripped; a regulating valve PV03 and a high-frequency solenoid valve SOV are provided, which work together, and combined with the regulating valve PV04 of the cooling gas branch, the bearing gas supply is stable and the differential pressure between the B port and the C1 port\C2 port of the turbine is maintained constant through a combination of fast and slow regulation; a pressure transmitter PT05 and a pressure transmitter PT06 are also provided, which take two out of two and calculate the bearing gas pressure difference comprehensively with the two pressure transmitters on the cooling gas branch.

[0046] In this embodiment, the cooling gas branch is provided with a flow meter FIQ02, a regulating valve PV04 and a temperature transmitter TT05, which are used to adjust the cooling gas flow of the expander to ensure that the temperature in the cavity is at a constant value; on the other hand, they are also used to compensate for the pressure difference of the bearing gas.

[0047] In this embodiment, the power gas enters from port A and impacts the first-stage impeller. After expansion and work, the natural gas temperature decreases, and a small amount of gas enters the stator and rotor chambers for stator cooling and is discharged from ports C1 and C2. The majority of the gas continues to impact the second-stage impeller, generating work, and is then discharged into the outlet pipeline from port D. Port B draws air for the air-floating bearings. At the same time, due to the higher air pressure in the first and second impeller chambers, the bearing gas enters the stator and rotor chambers and is discharged from ports C1 and C2 along with the cooling gas. The operating requirement of the air-floating turbine is to ensure that the pressure difference between the two ends of the bearing gas is maintained within a constant range.

[0048] This embodiment also proposes a control method for a natural gas floating differential pressure radial turbine power generation system. Figure 4 , applicable to the above-mentioned natural gas floating differential pressure radial turbine power generation system, including power generation power control, bearing gas control and safety control; power generation power control includes: input power set value W.SP and adjust it after calculating the error with the power feedback W.FB from the grid end, and output flow set value Q.SP, adjust it after calculating the error with the flow feedback Q.FB from FIQ01, and finally output the valve position value PV of the control valve to drive the main control valve PV01 and the main control valve PV02 for adjustment.

[0049] refer to Figure 4 , bearing gas control includes: calculating the error after calculating the differential pressure set value dP.SP and the feedback value dP.FB calculated comprehensively from the pressure transmitter PT05, pressure transmitter PT06, pressure transmitter PT07 and pressure transmitter PT08, and outputting the valve position value Y to the regulating valve PV03 and the high-frequency solenoid valve SOV.

[0050] refer to Figure 5 ,Safety control mainly includes signal, process control and electrical linkage control. ,Specific details are described here in detail as follows.

[0051] Specifically, the signals are mainly shutdown trigger signals, mainly turbine rotor overspeed, power imbalance (excessive current), filter failure, overpressure, overflow and overtemperature, bearing gas out of control, excessive vibration of the machine body, control system failure, online system failure (including abnormal disconnection from the power grid), process equipment failure, and manual shutdown.

[0052] In terms of process control, when a shutdown signal is received, the safety shut-off valve (SSV) will be triggered to cut off and the pneumatic ball valve (AOV) will balance the pressure. This will ensure that the unit speed is reduced in the process. At the same time, the stability of the bearing gas must be ensured and the bypass branch must be controlled for rapid compensation and adjustment to reduce disturbances to downstream users.

[0053] In the electrical system, a discharge device is set on one side of the turbine. The discharge device is equipped with a discharge resistor. When a shutdown signal is received, the discharge resistor is immediately put into the circuit to shorten the unit shutdown time and improve safety. Figure 5 As stated.

[0054] In this embodiment, the power generation control sets a cascade regulation mode of power → flow → valve position; however, there is an upper threshold for flow regulation, and when the upper threshold is exceeded, current limiting regulation will be performed; the power setting value has two types: grid AGC and manual setting, which need to be switched manually; in addition, flow regulation control can also be performed separately, and it is not affected by power regulation.

[0055] In this embodiment, the above control adopts single-stage mode regulation, and single-stage refers to single pressure difference regulation.

[0056] The bearing gas control adopts a single-stage, partitioned, and multi-interference input mode for adjustment. For the partition mode adjustment, partitioning refers to setting four values: high-high (HH), high (H), low (L), and low-low (LL). Among them, HH and LL are the warning values ​​of the turbine bearing gas supply pressure difference, and H and L are normal working values. Then, in the (-∞, LL], [HH, +∞) interval, it is adjusted by the regulating valve PV03, and in the (LL, HH) interval, it is adjusted by the high-frequency solenoid valve SOV. In addition, for the multi-interference input mode adjustment, multi-interference means that the feedback of the pressure difference is mainly affected by the change of the cooling air flow Q1 when the turbine load changes, the branch (downstream user of the station) outlet flow Q c Changes in buffer tank pressure (front-end gas working conditions) P c , the system design adopts feedforward control.

[0057] In this embodiment, security control can improve the security of the entire system.

[0058] The application sets a complete operation system based on the operation mode of the gas-floating differential pressure radial turbine generator set, so that the turbine set realizes stable operation, and the effective recovery of the natural gas pressure energy is realized.

[0059] The above examples are further elaboration and illustration of the application, so as to be understood, and are not any limitation of the application, any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A natural gas floating differential pressure radial turbine power generation system, characterized in that: It includes an independent branch, which includes a main branch. The main branch is equipped with a turbine, a bypass branch is connected in parallel to the main branch, a bearing air branch is connected in parallel to the front of the main branch, and a cooling air branch is connected in parallel to the rear of the main branch. The original station branch ball valve BV01 and the original station branch ball valve BV02 are respectively provided on both sides of the independent branch. The bearing air branch includes a check valve CHV01, which is connected to a buffer tank. The other end of the buffer tank is connected to a high-efficiency filter GF02. The high-efficiency filter GF02 is connected in parallel to a differential pressure transmitter PDT02. The other end of the differential pressure transmitter PDT02 is connected to a regulating valve PV03. The regulating valve PV03 is connected in parallel to a high-frequency solenoid valve SOV. The other end of the regulating valve PV03 is connected to a pressure transmitter PT05 and a pressure transmitter PT06 connected in series. The other end of the pressure transmitter PT06 is connected to the turbine. The cooling air branch includes a flow meter FIQ02, one end of the flow meter FIQ02 is connected to the pressure transmitter PT02, the other end of the flow meter FIQ02 is connected to the temperature transmitter TT02, the other end of the temperature transmitter TT02 is connected to the temperature transmitter TT05, the other end of the temperature transmitter TT05 is connected to the regulating valve PV04, and the other end of the regulating valve PV04 is connected to the other end of the temperature transmitter TT04; the other end of the pressure transmitter PT02 is connected to the pressure transmitter PT08, the pressure transmitter PT08 is connected to the C2 port of the turbine, the pressure transmitter PT08 is also connected to the pressure transmitter PT07, and the other end of the pressure transmitter PT07 is connected to the C1 port of the turbine.

2. A natural gas floating differential pressure radial turbine power generation system according to claim 1, characterized in that: The main branch also includes a filter separator GF01, which is connected in parallel with a differential pressure transmitter PDT01. The filter separator GF01 is connected to a natural gas metering component, and the other end of the natural gas metering component is connected to a temperature transmitter TT01. The other end of the temperature transmitter TT01 is connected to a safety shut-off valve SSV. The other end of the safety shut-off valve SSV is connected to a pressure transmitter PT03. The other end of the pressure transmitter PT03 is connected to a main regulating valve PV01. The main regulating valve PV01 is connected to the main regulating valve PV01. It is connected to a main regulating valve PV02, and the other end of the main regulating valve PV01 is connected to a pressure transmitter PT04, which is connected to the inlet side of the turbine, and the outlet side of the turbine is connected to a pressure transmitter PT09, and the other end of the pressure transmitter PT09 is connected to a temperature transmitter TT03 and a temperature transmitter TT04 connected in series, and the other end of the temperature transmitter TT04 is connected to a check valve CHV02, and the other end of the temperature transmitter TT04 is also connected to an electric stop valve ZFV.

3. A natural gas floating differential pressure radial turbine power generation system according to claim 2, characterized in that: The natural gas metering assembly includes a flow meter FIQ01 , one end of the flow meter FIQ01 is connected to a pressure transmitter PT01 , and the other end of the flow meter FIQ01 is connected to a temperature transmitter TT01 .

4. A natural gas floating differential pressure radial turbine power generation system according to claim 3, characterized in that: One end of the bypass branch is connected to the other end of the safety shut-off valve SSV, and the other end of the bypass branch is connected to the other end of the temperature transmitter TT04. The bypass branch includes a pneumatic ball valve AOV for pressure relief.

5. The natural gas floating differential pressure radial turbine power generation system according to claim 1, characterized in that: The regulating valve PV03 and the high-frequency solenoid valve SOV work together, and in conjunction with the regulating valve PV04 of the cooling air branch, they ensure the stable supply of bearing gas and maintain a constant differential pressure between the B port and the C1 port\C2 port of the turbine through a combination of fast and slow regulation.

6. A natural gas floating differential pressure radial turbine power generation system according to claim 1 or 2, characterized in that: The turbine comprises a first impeller (1) and a second impeller (5), wherein a plurality of air bearings (2) are provided on the inner sides of the middle of the first impeller (1) and the second impeller.

7. A control method for a natural gas floating differential pressure radial turbine power generation system, applicable to a natural gas floating differential pressure radial turbine power generation system according to claim 3 or 4, characterized in that: It includes power generation control, bearing gas control and safety control; the power generation control includes: inputting the power setting value W.SP, calculating the error with the power feedback W.FB from the grid-connected end and adjusting it, and outputting the flow setting value Q.SP, calculating the error with the flow feedback Q.FB from the flow meter FIQ01 and adjusting it, and finally outputting the valve position value PV of the regulating valve to the main regulating valve PV01 and the main regulating valve PV02.

8. The control method of a natural gas floating differential pressure radial turbine power generation system according to claim 7, characterized in that: The bearing gas control includes: calculating the error after adjusting the pressure difference set value dP.SP and the feedback value dP.FB calculated from the pressure transmitter PT05, pressure transmitter PT06, pressure transmitter PT07 and pressure transmitter PT08, and outputting the valve position value Y to the regulating valve PV03 and the high-frequency solenoid valve SOV.

9. The control method of a natural gas floating differential pressure radial turbine power generation system according to claim 8, characterized in that: The safety control mainly includes signal, process control and electrical linkage control.

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