A high-pressure decompression energy recovery device for biogenic natural gas

Abstract

The utility model discloses a kind of biological natural gas high-pressure decompression energy recovery devices, it is related to biogas treatment field, including natural gas turbine, the gas inlet of natural gas turbine is connected with upstream high-pressure main pipe by gas inlet pipeline, the gas outlet of natural gas turbine is connected with municipal pipe network by gas outlet pipeline, the output shaft of natural gas turbine is connected with generator;The utility model under the premise of not changing municipal grid-connected pressure, the pressure energy of about 0.6MPa pressure difference in decompression section is recovered and is converted into electric energy, provides the electric power required for operation for 7.5kW regenerative fan, forms self-energy supply system without external power supply.The scheme has the comprehensive advantages of energy saving and consumption reduction and being convenient to maintain etc., and maintains the stability of bus voltage and outlet pressure by the linkage control of full-power AFE and fan frequency converter, significantly improves the reliability and applicability of system operation.

Description

Technical Field

[0001] This utility model relates to the field of biogas treatment, specifically a biogas high-pressure decompression energy recovery device. Background Technology

[0002] Biogas, after purification, is typically at a relatively high pressure (e.g., 0.6–1.0 MPa), while municipal gas pipelines are mostly at medium or low pressure (approximately 0.1–0.4 MPa). Therefore, before grid connection, the incoming gas must be reduced from high pressure to the pipeline's allowable delivery pressure to avoid overpressure, meet grid connection agreements, and ensure metering and gas usage safety. For example, in a project processing 30,000 cubic meters of biogas per day, the biogas output from the decarbonization tower is approximately 800 Nm³ / h at a pressure of 0.9 MPa, which needs to be reduced to 0.3 MPa before grid connection.

[0003] In the currently widely used "equal enthalpy throttling" scheme of throttle valves / self-regulating pressure regulators, no work is done in reducing pressure, and the pressure potential energy corresponding to the pressure difference is directly dissipated in the form of turbulence and irreversible loss, which constitutes the main waste of resources. Utility Model Content

[0004] The purpose of this invention is to provide an integrated system for pressure reduction and stabilization and residual pressure power generation for grid-connected biogas, so as to solve the problem of energy dissipation during the pressure reduction process in the prior art.

[0005] The technical solution adopted by this utility model is as follows: a biogas high-pressure decompression energy recovery device, including a natural gas turbine, the gas inlet of the natural gas turbine is connected to the upstream high-pressure main pipe through the gas inlet pipe, the gas outlet of the natural gas turbine is connected to the municipal pipeline network through the gas outlet pipe, and the output shaft of the natural gas turbine is connected to a generator. A pneumatic regulating valve is installed at the inlet of the natural gas turbine. A bypass pipeline is installed between the upstream high-pressure main pipe and the pneumatic regulating valve. The end of the bypass pipeline away from the inlet pipeline is connected to the municipal pipeline network. A self-operated safety valve and a flow limiting orifice plate are installed sequentially on the bypass pipeline. A full-power active front-end converter is installed between the generator and the regenerator.

[0006] Furthermore, the natural gas turbine is a radial flow impulse turbine. Under rated operating conditions, the inlet pressure of the natural gas turbine is 0.9 MPa, the outlet pressure is 0.3 MPa, and the isentropic efficiency is not less than 0.60.

[0007] Furthermore, the generator is a high-speed permanent magnet generator with a speed of 24,000 r / min, IP55 explosion-proof rating, and outputs 380V / 50Hz three-phase power.

[0008] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: 1. This utility model, without altering the municipal grid connection pressure, recovers the pressure energy of approximately 0.6 MPa pressure difference in the pressure reduction section and converts it into electrical energy to provide the operating power required for a 7.5 kW regenerative fan, forming a self-powered system that requires no external power supply. This solution combines advantages such as energy saving, explosion-proof safety, small footprint, and low maintenance. Furthermore, through the linkage control of the full-power AFE and the fan inverter, it maintains the stability of the bus voltage and outlet pressure, significantly improving the reliability and applicability of the system operation. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a top view of the present invention.

[0010] Explanation of reference numerals in the attached figures: 1. Inlet pipe; 2. Pneumatic regulating valve; 3. Natural gas turbine; 4. Outlet pipe; 5. Generator; 6. Bypass pipe; 7. Self-operated safety valve; 8. Flow limiting orifice plate. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0012] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Example

[0013] Figures 1-2 As shown: A biogas high-pressure decompression energy recovery device includes a natural gas turbine 3. The inlet of the natural gas turbine 3 is connected to the upstream high-pressure main pipe through an inlet pipe 1, the outlet of the natural gas turbine 3 is connected to the municipal pipeline network through an outlet pipe 4, and the output shaft of the natural gas turbine 3 is connected to a generator 5. A pneumatic regulating valve 2 is installed at the inlet of the natural gas turbine 3. It is adjusted in a closed loop according to the downstream pipeline pressure to maintain the outlet pressure at 0.30±0.01Mpa. A bypass pipeline 6 is installed between the upstream high-pressure main pipe and the pneumatic regulating valve 2. The end of the bypass pipeline 6 away from the inlet pipeline 1 is connected to the municipal pipeline network. A self-operated safety valve 7 and a flow limiting orifice plate 8 are installed on the bypass pipeline 6 in sequence to ensure that natural gas can still be safely connected to the municipal pipeline network when the natural gas turbine 3 is under maintenance. A full-power active front-end converter is installed between generator 5 and the regenerator fan to realize the conversion of electrical energy between the output of the high-speed permanent magnet generator and the drive of the regenerator fan. The full-power active front-end converter stabilizes the voltage and is synchronously connected to the grid. Excess power is fed back to the low-voltage bus in the station. The regenerator fan is frequency-controlled soft-started and linked with the turbine power generation system.

[0014] Among them, natural gas turbine 3 is a radial flow impulse turbine. Under rated operating conditions, the inlet pressure of natural gas turbine 3 is 0.9MPa and the outlet pressure is 0.3MPa.

[0015] Generator 5 is a high-speed permanent magnet generator with a speed of 24,000 r / min and an output of 380V / 50Hz three-phase power.

[0016] By recovering the pressure energy of approximately 0.6 MPa pressure difference in the pressure reduction section and converting it into electrical energy without altering the municipal grid connection pressure, a self-powered system capable of operating without external power supply is formed, providing the necessary power for the operation of a 7.5 kW regenerative wind turbine. This solution offers comprehensive advantages such as energy saving, explosion-proof safety, small footprint, and low maintenance. Furthermore, the linkage control between the full-power AFE and the wind turbine frequency converter maintains the stability of the bus voltage and outlet pressure, significantly improving the reliability and applicability of the system.

[0017] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A biogas high-pressure decompression energy recovery device, comprising a natural gas turbine (3), wherein the inlet of the natural gas turbine (3) is connected to an upstream high-pressure main pipe through an inlet pipe (1), the outlet of the natural gas turbine (3) is connected to a municipal pipeline network through an outlet pipe (4), and the output shaft of the natural gas turbine (3) is connected to a generator (5). A pneumatic regulating valve (2) is installed at the inlet of the natural gas turbine (3). A bypass pipe (6) is installed between the upstream high-pressure main pipe and the pneumatic regulating valve (2). The end of the bypass pipe (6) away from the inlet pipe (1) is connected to the municipal pipeline network. A self-operated safety valve (7) and a flow limiting orifice plate (8) are installed on the bypass pipe (6) in sequence. A full-power active front-end converter is installed between the generator (5) and the regenerator fan.

2. The biogas high-pressure decompression energy recovery device according to claim 1, characterized in that: The natural gas turbine (3) is a radial flow impulse turbine; under rated operating conditions, the inlet pressure of the natural gas turbine (3) is 0.9 MPa and the outlet pressure is 0.3 MPa.

3. The biogas high-pressure decompression energy recovery device according to claim 2, characterized in that: The generator (5) is a high-speed permanent magnet generator with a rated speed of 24,000 r / min.

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