CO2 gas residual pressure power generation system

Abstract

The utility model discloses a CO2 gas residual pressure power generation system, which relates to the technical field of gas residual pressure utilization, and comprises a gas inlet pipeline, a gas outlet pipeline, a first pipeline, a second pipeline, a gas outlet pipeline, a gas inlet pipeline, a gas outlet pipeline and a gas outlet pipeline, an air inlet of the heater is connected with the other end of the first pipeline; one end of the second pipeline is connected with an air outlet of the heater; a turbine inlet of the generator set is connected with the other end of the second pipeline; one end of the third pipeline is connected with a turbine outlet of the generator set, and the other end is connected with the gas outlet pipeline; and the fourth pipeline is connected between the first pipeline and the third pipeline, and a first adjusting valve is connected to the fourth pipeline. Usable pressure energy lost in the pressure reducing valve is utilized to drive the runoff turbine to do work and drive the generator to generate electricity, generated electricity is merged into an internal power grid of a factory, part of electricity purchased by the factory can be reduced, and economic benefits of the factory are increased.

Description

Technical Field

[0001] This utility model relates to the field of gas residual pressure utilization technology, and in particular to a CO2 gas residual pressure power generation system. Background Technology

[0002] The cryogenic methanol washing unit is a technology used to purify synthesis gases (such as hydrogen and carbon monoxide). It is mainly used to remove acidic components from the gas. This process utilizes the high solubility of methanol in these acidic gases at low temperatures, thereby achieving effective separation and purification. The cryogenic methanol washing unit has pressurized CO2 gas, which is reduced in pressure by throttling and then enters a liquid separator to remove liquid. Then it enters a compressor to increase the pressure, and the pressurized CO2 gas is sent to subsequent processes. The CO2 gas is depressurized by a throttling valve, which wastes the available pressure energy in the CO2 gas. Utility Model Content

[0003] To address the problems of existing technologies, this utility model provides a CO2 gas residual pressure power generation system, comprising: an inlet pipe and an outlet pipe connected to each other, wherein a pressure reducing valve is installed on the inlet pipe, and further comprising:

[0004] The first pipeline has one end connected to the air intake pipeline;

[0005] The heater has its air inlet connected to the other end of the first pipeline;

[0006] The second pipeline is connected at one end to the air outlet of the heater;

[0007] The generator set has its turbine inlet connected to the other end of the second pipeline.

[0008] The third pipeline has one end connected to the turbine outlet of the generator set and the other end connected to the exhaust pipeline.

[0009] A fourth pipeline is connected between the first pipeline and the third pipeline, and a first regulating valve is connected to the fourth pipeline.

[0010] Furthermore, a first shut-off valve is connected to the first pipeline.

[0011] Furthermore, a second regulating valve is connected to the second pipeline.

[0012] Furthermore, a second shut-off valve and a third shut-off valve are connected to the third pipeline.

[0013] The beneficial effects of the technical solution provided by this utility model are as follows: In this utility model, a gas generator set is built in parallel with the existing gas pressure reducing valve. The usable pressure energy lost in the pressure reducing valve is used to drive the runoff turbine to do work, which drives the generator to generate electricity. The generated electricity is fed into the factory's internal power grid, so the factory can purchase less electricity and increase the factory's economic benefits. At the same time, the recycling of this part of the originally wasted energy can also create social benefits of energy conservation and emission reduction. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a CO2 gas residual pressure power generation system provided by this utility model.

[0015] Reference numerals in the attached diagram: 1-Inlet pipe; 2-Outlet pipe; 3-Pressure reducing valve; 4-First pipe; 5-Heater; 6-Second pipe; 7-Generator set; 8-Third pipe; 9-Fourth pipe; 10-First regulating valve; 11-First shut-off valve; 12-Second regulating valve; 13-Second shut-off valve; 14-Third shut-off valve. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0018] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "bottom," "top," "left," and "right" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and for simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] It should also be noted that, in this embodiment, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] First, it should be noted that in the existing low-temperature methanol washing device, there is pressurized CO2 gas. The pressure reducing valve 3 on the inlet pipe 1 reduces the pressure of the gas and then enters the liquid separator to remove the liquid. Then it enters the compressor to increase the pressure. The pressurized CO2 gas is sent to the subsequent process through the outlet pipe 2. The molar composition of CO2 in the pressurized CO2 gas is 99.3%.

[0021] See Table 1, which shows the parameters of CO2 gas before and after throttling and pressure reduction.

[0022] Table 1

[0023] process parameters numerical values unit Remark Gas flow rate 29000 <![CDATA[Nm 3 / h]]> <![CDATA[Range: 20000 to 32000 Nm 3 / h]]> Import pressure 0.21 MPaG Before throttling and decompression Inlet temperature 22 ℃ Rated temperature, before throttling and pressure reduction, range 15–28℃ Export pressure 0.055 MPaG After throttling and pressure reduction, the pressure required for subsequent processes... outlet temperature 15 ℃ After throttling and pressure reduction, the temperature required for subsequent processes...

[0024] As can be seen from Table 1, the CO2 gas from the low-temperature methanol wash has a certain pressure. Reducing the pressure of the gas through the pressure reducing valve 3 on the inlet pipe 1 wastes the available pressure energy in the gas. Therefore, this invention designs a CO2 gas residual pressure power generation system, including a first pipe 4 connected to the inlet pipe 1, the other end of the first pipe 4 connected to the inlet of the heater 5, a second pipe 6 connected to the outlet of the heater 5, the other end of the second pipe 6 connected to the turbine inlet of the generator set 7, a third pipe 8 connected to the turbine outlet of the generator set 7, the other end of the third pipe 8 connected to the outlet pipe 2, and a fourth pipe 9 connected between the first pipe 4 and the third pipe 8, with a first regulating valve 10 installed on the fourth pipe 9.

[0025] CO2 gas is introduced into heater 5 through the first pipeline 4. This is because after the CO2 gas expands and does work in the generator set, the internal energy of the CO2 gas decreases and the temperature drops to below zero. This not only fails to meet the temperature requirements of the subsequent processes for CO2 gas, but also causes condensation or even ice formation on the outside of the gas pipeline separator after the generator set. Therefore, to solve this problem, the gas needs to be heated before the generator set inlet so that the temperature of the CO2 gas supplied to the subsequent processes meets the requirements.

[0026] The heated CO2 gas enters generator set 7. By replacing pressure reducing valve 3 with generator set 7, the usable energy lost during the throttling process can be converted into electricity, recovering a portion of high-quality energy. The generated electricity is fed into the factory's internal power grid, allowing the factory to purchase less electricity and increasing its economic benefits. At the same time, recovering and utilizing this previously wasted energy also creates social benefits of energy conservation and emission reduction.

[0027] To ensure system safety, after the new generator set is built, a bypass (fourth pipeline 9) is connected in parallel to the existing gas pressure reducing valve 3. The first regulating valve 10 is installed on the bypass as a backup bypass for the original pressure reducing valve.

[0028] To ensure adequate flow to the subsequent CO2 compressor and prevent surge, the operation mode of the newly built residual pressure generator unit is as follows:

[0029] Under normal operating conditions, the gas pressure reducing valve 3 is closed, and all gas passes through the generator set 7 to generate electricity. A second regulating valve 12 is connected to the second pipeline 6. When the generator set 7 experiences a major fault and needs to be shut down, the gas pressure reducing valve 3 is opened. When the opening of the pressure reducing valve reaches the normal operating position, the second regulating valve 12 before the generator set 7 is closed, causing the unit to shut down.

[0030] If the pressure reducing valve 3 malfunctions, open the first regulating valve 10 on the newly added bypass. When the opening of the first regulating valve 10 reaches the predetermined valve position, close the second regulating valve 12 before the generator set 7 to shut down the unit.

[0031] When generator set 7 is disconnected from the grid, the shaft brake installed on the motor shaft extension end is activated to prevent generator set 7 from overspeeding. At the same time, the shutdown procedure for generator set in case of major fault is executed.

[0032] A second shut-off valve 13 is installed on the third pipeline 8 at the outlet of generator set 7. After the second regulating valve 12 and the second shut-off valve 13 are closed, the generator set can be completely isolated from the gas pipeline, which facilitates fault handling and routine maintenance of the generator set.

[0033] During unit maintenance, to ensure safety and prevent minor leaks in the second regulating valve 12 and the second shut-off valve 13, the first shut-off valve 11 connected to the first pipeline 4 and the third shut-off valve 14 connected to the third pipeline 8 can also be closed.

[0034] See Figure 1 The generator set consists of the following parts: Generator Main Unit: This is a skid-mounted integrated unit that integrates a high-speed radial flow turbine expander, a high-speed gear reducer, a flexible coupling, an asynchronous generator, a motor shaft brake, and a lubrication and cooling system on a skid-mounted base. Grid-connected Electrical System: This includes a grid-connected switchgear. Monitoring and Control System: This includes monitoring and control instruments (connected to the factory's DCS system).

[0035] The generator set's outlet is directly connected to the CO2 compressor, which has stringent requirements for the parameters of the inlet gas, mainly including the following: a stable and appropriate flow rate, a stable and appropriate pressure, and a stable and appropriate temperature. If these requirements cannot be ensured, the compressor may trip, leading to a complete plant shutdown and causing a serious production accident.

[0036] Therefore, the generator set must ensure that the CO2 parameters at its outlet are stable and within the appropriate range required by the compressor. During normal operation of the residual pressure generator set, by adjusting the second regulating valve 12 before the generator set inlet, the adjustable guide vanes at the generator set inlet, and the cooling water flow rate of the heater 5 before the generator set inlet, the flow rate, pressure, and temperature of the CO2 gas at the generator set outlet can be ensured to be stable, and the values ​​of each parameter can be guaranteed to be within the range required for stable operation of the compressor.

[0037] When a generator set experiences a major fault and needs to be shut down, the control system employs a slow shutdown method to ensure the stability of the CO2 gas parameters at the generator set outlet. The control and regulation process is as follows: the second regulating valve 12 on the generator set's upstream pipeline and the opening of the adjustable guide vanes at the generator set inlet are slowly closed. Simultaneously, the pressure reducing valve 3 on the original intake pipeline 1 is slowly opened. All of the above processes are automatically regulated based on the pressure before the CO2 compressor. The cooling water flow rate of the generator set's upstream heater is also automatically regulated based on the temperature before the CO2 compressor. This process is repeated until the second regulating valve 12 on the generator set is completely closed, the pressure reducing valve 3 on the original intake pipeline 1 is opened to the appropriate position, and the CO2 gas is completely switched from the generator set to the original intake pipeline 1.

[0038] When a residual pressure generator set experiences grid disconnection, the turbine expander loses its load. The expander shaft power of several hundred kilowatts drives a very small load (such as friction in the gearbox and motor bearings). If no measures are taken, the residual pressure generator set will overspeed. In this situation, the following adjustment and control scheme is adopted: First, using the adjustable hydraulic shaft brake installed on the motor shaft extension end, slowly brake the generator set to prevent overspeed and reduce its speed. Simultaneously, reduce the opening of the adjustable guide vanes at the turbine expander inlet to ensure the flow and pressure of CO2 gas at the generator set outlet remain stable until the generator set speed is reduced to zero, and the generator set stops. Second, after the generator set stops, slowly close the second regulating valve 12 on the generator set's front pipeline. Simultaneously, open the pressure reducing valve 3 on the original intake pipeline 1, following the same process as the shutdown procedure during a major fault, until the CO2 gas is completely switched from the generator set to the original intake pipeline 1.

[0039] It should be noted that in this embodiment, generator set 7 adopts a high-efficiency, high-speed run-of-river turbine generator set from Tianjin Fast Turbine Technology Development Co., Ltd. It is applicable to the MW range and is currently the most efficient prime mover, with an isentropic efficiency exceeding 90%. Within this power range, its average efficiency is more than 50% higher than that of screw turbines and 100-200% higher than that of small industrial steam turbines. All moving parts (impellers, bearings, seals, etc.) are non-contact, resulting in long service life and high reliability.

[0040] The process parameters of the waste pressure power generation system are shown in Table 2.

[0041] Table 2

[0042]

[0043]

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A CO2 gas excess pressure power generation system comprising: An intake pipe (1) and an outlet pipe (2) are connected, wherein a pressure reducing valve (3) is provided on the intake pipe (1), characterized in that it further includes: The first pipeline (4) is connected at one end to the intake pipeline (1); The heater (5) has its air inlet connected to the other end of the first pipeline (4); The second pipeline (6) is connected at one end to the air outlet of the heater (5); The generator set (7) has its turbine inlet connected to the other end of the second pipeline (6); The third pipeline (8) is connected at one end to the turbine outlet of the generator set (7) and at the other end to the exhaust pipeline (2). The fourth pipeline (9) is connected between the first pipeline (4) and the third pipeline (8), and the fourth pipeline (9) is connected to the first regulating valve (10).

2. The CO2 gas excess pressure power generation system according to claim 1, characterized by, A first shut-off valve (11) is connected to the first pipeline (4).

3. The CO2 gas pressure power generation system according to claim 1, wherein A second regulating valve (12) is connected to the second pipeline (6).

4. The CO2 gas waste pressure power generation system according to claim 1, characterized in that, The third pipeline (8) is connected to a second shut-off valve (13) and a third shut-off valve (14).

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