Nitrogen flow control system

Abstract

The utility model provides a nitrogen flow control system which comprises a plurality of control valves, an inlet of each control valve is connected with an outlet of a nitrogen buffer tank, and outlets of all the control valves are connected to a gas outlet gathering end. Wherein the at least two control valves have different flow ranges; the different purging branches execute purging operation under different working conditions, and an air inlet of each purging branch is connected with the air outlet gathering end; the PLC is connected with the controlled end of each control valve; and the PLC controls different control valves to act so as to control the nitrogen flow of the gas outlet gathering end. According to the scheme, nitrogen flow control of various working conditions in the gasification process can be more accurately achieved, the control precision of the small-flow use working condition can be guaranteed, the continuous nitrogen use amount during normal operation of the gasification furnace can be met, the control precision of the large-flow use working condition can be guaranteed, and the purging nitrogen use amount under different shutdown working conditions can be guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal gasification, and in particular relates to a nitrogen flow control system. Background Art

[0002] The gasifier is a high-temperature and high-pressure equipment. The high-temperature synthesis gas generated by the reaction is flammable and explosive. When the pulverized coal burner or ignition burner triggers the safety interlock shutdown, high-pressure nitrogen must be started for purging and replacement to ensure that the oxygen system is effectively isolated from the high-temperature synthesis gas environment of the gasifier, and to prevent the high-temperature synthesis gas from flowing back into the oxygen system and causing explosions and other safety accidents.

[0003] Usually, the nitrogen purging equipment includes a nitrogen flow control system, which is connected between the outlet of the high-pressure nitrogen buffer tank and the purging component to control the nitrogen flow. In the prior art, the nitrogen flow control system includes a control valve, and when the opening of the control valve changes, the nitrogen flow changes. Because the nitrogen flow required for the shutdown purging of a single burner is different from that required for the shutdown purging of all burners, the continuous nitrogen consumption during normal operation is also different from the nitrogen consumption for purging during fault shutdown. Therefore, the nitrogen flow rate has a large range of variation. If a control valve is used to achieve nitrogen flow control, the control valve needs to have a large range of opening variation, and it is difficult to meet the control accuracy at a small flow rate. Therefore, the nitrogen purging equipment of the prior art is difficult to simultaneously meet the range and accuracy requirements of nitrogen consumption for different shutdown conditions of various gasifiers, especially for large-scale dry powder or water-coal slurry gasification, which needs to consider a larger adjustment range, and this problem is particularly prominent. Utility Model Content

[0004] The utility model provides a nitrogen flow control system, which is used to solve the technical problem of low precision in multi-operating-condition nitrogen flow control in the prior art.

[0005] In order to solve the above technical problems, the technical solution of the present application provides a nitrogen flow control system, comprising:

[0006] Multiple control valves, each of which has an inlet connected to the outlet of the nitrogen buffer tank, and all of which have outlets connected to the gas outlet collection terminal; wherein at least two of the control valves have different flow ranges;

[0007] A plurality of purge branches, different purge branches perform purge operations under different working conditions, and the air inlet of each purge branch is connected to the air outlet collection end;

[0008] A PLC controller is connected to a controlled end of each control valve; the PLC controller controls the actions of different control valves to control the nitrogen flow at the gas outlet aggregation end.

[0009] In some schemes, the nitrogen flow control system described in the purge branch includes a continuous nitrogen use purge branch and a shutdown purge branch; the shutdown purge branch includes multiple burner shutdown purge branches.

[0010] In some schemes, the nitrogen flow control system described in the burner stop purge branch includes at least three pulverized coal burner stop purge branches and one ignition burner stop purge branch.

[0011] In some schemes, the nitrogen flow control system is provided with a branch flow meter on each purge branch, and the branch flow meter detects the nitrogen flow value of the branch and sends it to the PLC controller.

[0012] In some embodiments of the nitrogen flow control system, the plurality of control valves include a first control valve, a second control valve, and a third control valve;

[0013] The first control valve provides nitrogen flow regulation for continuous nitrogen use purging, and the second control valve and the third control valve are used for nitrogen flow regulation for shutdown purging.

[0014] The nitrogen flow control system described in some embodiments further includes:

[0015] The first pressure sensor is arranged between the gas outlet aggregation end and the gas inlets of the multiple purge branches. When the first control valve and / or the second control valve is actuated, the first pressure sensor detects the pressure value of the nitrogen entering the purge branch and sends it to the PLC controller.

[0016] The nitrogen flow control system described in some embodiments further includes:

[0017] The second pressure sensor is arranged between the gas outlet aggregation end and the gas inlet of the multiple purge branches. When the first control valve, the second control valve and the third control valve are all actuated, the second pressure sensor detects the pressure value of the nitrogen entering the purge branch and sends it to the PLC controller.

[0018] In some embodiments of the nitrogen flow control system, the set value of the second pressure sensor is smaller than the set value of the first pressure sensor, and the difference between the two is a preset pressure difference.

[0019] In some embodiments of the nitrogen flow control system, the PLC controller is a PID controller.

[0020] In some schemes, the nitrogen flow control system described in the PLC controller is communicatively connected with the workstation host, and the PLC controller reports the detection data of the first pressure sensor, the second pressure sensor and the branch flow meter to the workstation host.

[0021] Compared with the prior art, the above technical solution provided by this application has at least the following technical effects:

[0022] The utility model provides a nitrogen flow control system, which can more accurately realize nitrogen flow control under various working conditions in the gasification process. A plurality of control valves are arranged between the nitrogen buffer tank outlet and each purge branch, and at least two control valves have different flow ranges. The actions of different control valves are realized by a PLC controller, and a larger range of nitrogen flow regulation control can be realized. Therefore, the control accuracy of the working condition of small flow can be guaranteed to meet the continuous nitrogen consumption during the normal operation of the gasifier, and the control accuracy of the working condition of large flow can be guaranteed to ensure the purge nitrogen consumption under different parking conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a nitrogen flow control system according to an embodiment of the present application;

[0024] Figure 2 This is a schematic structural diagram of a nitrogen flow control system according to another embodiment of the present application;

[0025] Figure 3 A schematic diagram of the port connection relationship of the PLC controller described in an embodiment of the present application.

[0026] The parts represented by the reference numerals are as follows:

[0027] 10-control valve, 20-air blowing branch, 30-PLC controller, 40-nitrogen buffer tank, 50-workstation host; 111-first control valve, 112-second control valve, 113-third control valve, 114-first pressure sensor, 115-second pressure sensor, 116-first branch flowmeter, 117-second branch flowmeter, 118-third branch flowmeter, 119-fourth branch flowmeter, 120-fifth branch flowmeter, 201-continuous nitrogen use purge branch, 202-coal powder burner A stop purge branch, 203-coal powder burner B stop purge branch, 204-coal powder burner C stop purge branch, 205-ignition burner stop purge branch. DETAILED DESCRIPTION

[0028] The specific implementation of the present application is further described below with reference to the accompanying drawings.

[0029] It is easy to understand that according to the technical solution of the present application, without changing the essential spirit of the present application, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the entirety of the present application or as a limitation or restriction on the technical solution of the application.

[0030] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0031] This embodiment provides a nitrogen flow control system, such as Figure 1 As shown, it includes multiple control valves 10, multiple purge branches 20 and a PLC controller 30, wherein the inlet of each of the multiple control valves 10 is connected to the outlet of the nitrogen buffer tank 40, and the outlets of all the control valves 10 are connected to the gas outlet aggregation end; wherein at least two of the control valves 10 have different flow ranges. Different purge branches 20 in the multiple purge branches 20 perform purge operations under different working conditions, and the air inlet of each purge branch 20 is connected to the gas outlet aggregation end; the PLC controller 30 is connected to the controlled end of each control valve 10; the PLC controller 30 controls the actions of different control valves 10 to control the nitrogen flow at the gas outlet aggregation end.

[0032] The above scheme provided in this embodiment can more accurately realize the nitrogen flow control of various working conditions in the gasification process. A plurality of control valves 10 are arranged between the outlet of the nitrogen buffer tank 40 and each purge branch 20, and at least two control valves 10 have different flow ranges. The actions of different control valves 10 are realized by the PLC controller 30, so that a wider range of nitrogen flow regulation control can be realized. Therefore, the control accuracy of the small flow condition can be guaranteed to meet the continuous nitrogen consumption during the normal operation of the gasifier, and the control accuracy of the large flow condition can be guaranteed to ensure the purge nitrogen consumption under different parking conditions.

[0033] In some embodiments, the purge branch 20 includes a continuous nitrogen use purge branch and a stop purge branch; the stop purge branch includes multiple burner stop purge branches. In specific implementation, the nitrogen flow required for a single burner stop purge and all burners stop purge will be different. The continuous nitrogen usage during normal operation is smaller than the purge nitrogen usage during parking. Therefore, through the solution of the present application, the different working conditions included in the continuous nitrogen use purge branch and the stop purge branch can be fully considered.

[0034] In some solutions of the present application, the burner stop purge branch in the gas flow control system includes at least three pulverized coal burner stop purge branches and one ignition burner stop purge branch. Figure 2As shown, the purge branches include five: a continuous nitrogen use purge branch 201, a pulverized coal burner A stop purge branch 202, a pulverized coal burner B stop purge branch 203, a pulverized coal burner C stop purge branch 204, and an ignition burner stop purge branch 205. The multiple control valves include a first control valve 111, a second control valve 112, and a third control valve 113; wherein the first control valve 111 provides nitrogen flow regulation for continuous nitrogen use purge, and the second control valve 112 and the third control valve 113 are used for nitrogen flow regulation for stop purge. That is, as Figure 2 As shown in , the first control valve 111, the second control valve 112 and the third control valve 113 are installed as actuators on three parallel pipelines at the outlet of the high-pressure nitrogen buffer tank. The first control valve 111, the second control valve 112 and the third control valve 113 are connected in parallel, wherein the first control valve 111 can be selected as a valve with a smaller specification for flow regulation during continuous nitrogen use, and the second control valve 112 and the third control valve 113 can be selected as valves with larger specifications for purge nitrogen flow regulation when the gasifier is stopped. Small-sized valves have greater accuracy when regulating flow in a smaller range, and can improve accuracy when regulating large flow rates when combined with two large-sized valves.

[0035] Furthermore, the PLC controller is a PID controller. In the above scheme, each of the purge branches is provided with a branch flow meter, and the branch flow meter detects the nitrogen flow value of the branch and sends it to the PLC controller 30. Figure 2 As shown, taking five purge branches as an example, a first branch flowmeter 116 is provided on the continuous nitrogen use purge branch 201, a second branch flowmeter 117 is provided on the pulverized coal burner A stop purge branch 202, a third branch flowmeter 118 is provided on the pulverized coal burner B stop purge branch 203, a fourth branch flowmeter 119 is provided on the pulverized coal burner C stop purge branch 204, and a fifth branch flowmeter 120 is provided on the ignition burner stop purge branch 205. Each branch flowmeter sends the detected data to the PLC controller. Since the switching between different working conditions will cause a relatively large change in the nitrogen flow rate, the branch flowmeters at each purge branch are used to detect the nitrogen consumption and send it to the PLC controller 30 as the data basis for feedforward control, so as to make rough adjustments to the interference caused by the switching of different working conditions in a timely manner and reduce the burden of feedback control.

[0036] Preferably, if Figure 2As shown, the nitrogen flow control system also includes a first pressure sensor 114, which is arranged between the gas outlet aggregation end and the air inlet of the multiple purge branches 20. When the first control valve 111 and / or the second control valve 112 is actuated, the first pressure sensor 114 detects the pressure value of the nitrogen entering the purge branch 20 and sends it to the PLC controller 30. Furthermore, the nitrogen flow control system also includes a second pressure sensor 115, which is arranged between the gas outlet aggregation end and the air inlet of the multiple purge branches 20. When the first control valve 111, the second control valve 112 and the third control valve 113 are all actuated, the second pressure sensor 115 detects the pressure value of the nitrogen entering the purge branch 20 and sends it to the PLC controller 30. Through the solution of the present application, the pressure signal feedback control of the PLC controller can be realized. Figure 2 The control loop shown adopts the split-range control of the first control valve 111 and the second control valve 112, combined with the single-loop control of the third control valve 113. In coordination with the branch flowmeters of each purge branch 20, the coordinated regulation of positive feedback and negative feedback can be achieved.

[0037] Furthermore, the set value of the second pressure sensor 115 is smaller than the set value of the first pressure sensor 114, and the difference between the two is a preset pressure difference, and the preset pressure difference is smaller than 0.5 MPa, for example, 0.1 MPa can be selected. Figure 3As shown, in the split-range control of the first control valve 111 and the second control valve 112, the detection result of the first pressure sensor 114 is input to the PLC controller 30 as a feedback signal of the split-range control, and the set value of the first pressure sensor 114 is SP. When any burner is not triggered to stop, the split-range control adjusts the first control valve 111 to meet the continuous nitrogen consumption. At this time, the smaller-sized first control valve 111 can ensure the regulation accuracy of the continuous nitrogen consumption; when a single burner is triggered to stop, the first control valve 111 cannot meet the nitrogen consumption even if the opening is 100%, and the second control valve 112 in the split-range control slowly opens to ensure that the detection value of the first pressure sensor 114 is stable at the set value SP. In addition, in the single-loop control of the third control valve 113, the second pressure sensor 115 is used as the feedback signal of the single-loop control, and the set value is SP-0.1MPa; if the two burners are triggered to stop or even all the burners are stopped, if the split-range control can meet the nitrogen consumption to ensure that the pressure signal is stable at the SP value, since the SP value of the single-loop control is 0.1MPa less than the SP value of the split-range control, the third control valve 113 will not open; if the split-range control cannot meet the nitrogen consumption and causes the pressure signal value to decrease, the third control valve 113 will slowly open to stabilize the detection value of the second pressure sensor 115 at the set value SP-0.1MPa. The above scheme provided in this embodiment adopts a combination structure of different control valves and pressure sensor detection values, realizes the flow control structure of split-range control and single loop, ensures the adjustment accuracy of different step flow control, and ensures the precise adjustment of nitrogen consumption under different working conditions. For example: the first pressure sensor 114 and the second pressure sensor 115 form a feedback control loop as the controlled object, and the total nitrogen consumption at each purge branch is used as a feedforward control. Assuming that the setting value of the first pressure sensor 114 is 5.7 MPa, when any burner does not trigger the shutdown, the first control valve 111 can be adjusted by range control to meet the continuous nitrogen consumption of 50-150 Nm 3 / h, and can ensure the regulation accuracy of continuous nitrogen consumption; when a single burner is triggered to stop, the nitrogen consumption reaches 1000-2000Nm 3 / h, the first control valve 111 cannot meet the requirement even if the opening is 100%, and the second control valve 112 is slowly opened to stabilize the first pressure sensor 114 at the set value of 5.7MPa. In addition, in the single-loop control of the third control valve, the detection result of the second pressure sensor 115 is used as the feedback signal of the single-loop control, and the set value is 5.6MPa; if the nitrogen consumption reaches 4000-6000Nm when two burners are stopped or even all burners are stopped 3 / h, if the split-range control can meet the nitrogen consumption and ensure that the pressure signal of the first pressure sensor is stable at 5.7MPa, the third control valve 113 will not open; if the split-range control cannot meet the nitrogen consumption and causes the pressure signal of the second pressure sensor to be lower than 5.6MPa, the third control valve will slowly open to achieve the second pressure sensor 115 stable at the set value of 5.6MPa.

[0038] Furthermore, in the above scheme, if Figure 2 As shown, the PLC controller 30 and the workstation host 50 also realize communication connection, and the PLC controller 30 reports the detection data of the first pressure sensor 114, the second pressure sensor 115 and the branch flow meter to the workstation host 50, and the workstation host 50 can be configured with a display screen to display the relevant data for the staff to view. In the above scheme, the connection between the PLC controller 30 and other components can be connected by cable or wirelessly, as long as the data transmission can be completed.

[0039] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0040] The above are only the principles and preferred embodiments of the present application. It should be noted that, for ordinary technicians in this field, on the basis of the principles of the present application, several other modifications can be made, which should also be considered as the protection scope of the present application.

Claims

1. A nitrogen flow control system, characterized in that: include: Multiple control valves, each of which has an inlet connected to the outlet of the nitrogen buffer tank, and all of which have outlets connected to the gas outlet collection terminal; wherein at least two of the control valves have different flow ranges; A plurality of purge branches, different purge branches perform purge operations under different working conditions, and the air inlet of each purge branch is connected to the air outlet collection end; A PLC controller is connected to a controlled end of each control valve; the PLC controller controls the actions of different control valves to control the nitrogen flow at the gas outlet aggregation end.

2. The nitrogen flow control system according to claim 1, characterized in that: The purge branch includes a continuous nitrogen use purge branch and a shutdown purge branch; the shutdown purge branch includes a plurality of burner shutdown purge branches.

3. The nitrogen flow control system according to claim 2, characterized in that: The burner stop and purge branch circuits include at least three pulverized coal burner stop and purge branch circuits and one ignition burner stop and purge branch circuit.

4. The nitrogen flow control system according to claim 3, characterized in that: Each of the purge branches is provided with a branch flow meter, which detects the nitrogen flow value of the branch and sends it to the PLC controller.

5. The nitrogen flow control system according to any one of claims 2 to 4, characterized in that: The plurality of control valves include a first control valve, a second control valve and a third control valve; The first control valve provides nitrogen flow regulation for continuous nitrogen use purging, and the second control valve and the third control valve are used for nitrogen flow regulation for shutdown purging.

6. The nitrogen flow control system according to claim 5, characterized in that: Also includes: The first pressure sensor is arranged between the gas outlet aggregation end and the gas inlets of the multiple purge branches. When the first control valve and / or the second control valve is actuated, the first pressure sensor detects the pressure value of the nitrogen entering the purge branch and sends it to the PLC controller.

7. The nitrogen flow control system according to claim 6, characterized in that: Also includes: The second pressure sensor is arranged between the gas outlet aggregation end and the gas inlet of the multiple purge branches. When the first control valve, the second control valve and the third control valve are all actuated, the second pressure sensor detects the pressure value of the nitrogen entering the purge branch and sends it to the PLC controller.

8. The nitrogen flow control system according to claim 7, characterized in that: The set value of the second pressure sensor is smaller than the set value of the first pressure sensor, and the difference between the two is a preset pressure difference.

9. The nitrogen flow control system according to claim 8, characterized in that: The PLC controller is a PID controller.

10. The nitrogen flow control system according to claim 9, characterized in that: The PLC controller is in communication connection with the workstation host, and the PLC controller reports the detection data of the first pressure sensor, the second pressure sensor and the branch flow meter to the workstation host.

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