Method and device for stabilizing the amount of vacuum regenerated gas

Abstract

The present application relates to a kind of stable vacuum regeneration gas quantity method and device, including using frequency conversion vacuum equipment to regenerate adsorbent, pressure gauge is arranged at the import and export of vacuum equipment, communication side line is arranged between pipeline before import and export pressure gauge, first regulating valve is arranged on side line, second regulating valve and flow limiting equipment are connected in parallel after import and export pressure gauge, then flowmeter is arranged;Before vacuum regeneration starts, first regulating valve opens, and second regulating valve closes;After vacuum regeneration starts, outlet flow is kept stable using three-stage control.The present application realizes the stability of adsorbent vacuum regeneration gas quantity without setting buffer facility, and avoids the impact of gas fluctuation on subsequent reuse device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of air pollution control, and particularly relates to a method and device for stabilizing vacuum regeneration gas quantity. BACKGROUND

[0002] The gas adsorption process is widely used in the fields of gas purification and waste gas treatment, and the industrial supporting adsorbent regeneration method mainly includes thermal regeneration and vacuum regeneration, wherein the vacuum regeneration is particularly widely applied due to its simple operation, short regeneration time, safe process and other characteristics. In the conventional vacuum regeneration process, due to the operation curve of the vacuum pump and the process characteristics, the regeneration gas quantity is difficult to stabilize, and the gas quantity fluctuation range is large. When the adsorbent vacuum regeneration gas needs to enter the subsequent reuse device with high gas quantity stability requirement, a great impact on the subsequent reuse device is caused, and it is difficult to maintain stable operation.

[0003] In view of this problem, at present, in the industrial device design practice, a buffer tank is generally arranged after the vacuum pump. Since the outlet pressure of the vacuum pump is not high, in order to meet the buffering effect, the size of the buffer tank is large. In order to reduce the size of the buffer tank, some designs need to connect a compressor in series at the outlet of the vacuum pump, so that the vacuum regeneration gas is compressed and then enters the buffer tank, so as to reduce the size of the buffer tank and improve the buffering efficiency. This will inevitably cause the increase of land occupation, operation cost and initial investment cost. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a method and device for stabilizing vacuum regeneration gas quantity. The present application realizes the stability of the adsorbent vacuum regeneration gas quantity without setting a buffering facility, and avoids the impact of gas quantity fluctuation on the subsequent reuse device.

[0005] The method for stabilizing vacuum regeneration gas quantity provided by the present application includes the following contents:

[0006] The adsorbent is regenerated by using a variable frequency vacuum device, pressure gauges are arranged at the inlet and outlet of the vacuum device, a communication side line is arranged between the pipelines in front of the inlet and outlet pressure gauges, a first regulating valve is arranged on the side line, a second regulating valve and a flow limiting device are arranged in parallel after the outlet pressure gauge, and then a flowmeter is arranged; before the vacuum regeneration is started, the first regulating valve is opened, and the second regulating valve is closed; after the vacuum regeneration is started, the outlet flow is kept stable by using three-level control, the first-level control is realized by associating the flowmeter, the second regulating valve and the flow limiting device to form a closed loop regulation, when the second regulating valve is close to full opening and still cannot keep the flow, the second-level control is started; the second-level control is realized by associating the flowmeter and the first regulating valve to form a closed loop regulation, when the first regulating valve is close to full closing, the third-level control is started; the third-level control is realized by associating the flowmeter and the vacuum device to form a closed loop regulation, when the frequency of the vacuum device reaches 100% of the maximum frequency, the vacuum regeneration is stopped.

[0007] In the present application, before starting the vacuum regeneration, the frequency conversion of the vacuum equipment is set to 10% to 90% of the total frequency, preferably 40% to 60%.

[0008] In the present application, before starting the vacuum regeneration, the first regulating valve is opened, and the opening degree is 10% to 100%, preferably 60% to 80%.

[0009] In the first stage control, the flow limiting device limits the outlet pressure of the vacuum equipment to 1 to 30 KPaG, preferably 2 to 10 KPaG, and the opening degree of the second regulating valve is controlled through the flow meter, that is, a predetermined flow is set, and the signal is transmitted to the second regulating valve to control the opening degree, so as to stabilize the outlet flow. When the second regulating valve approaches full opening, that is, the opening degree is not less than 90%, and the set flow cannot be maintained, the second stage control is started.

[0010] In the second stage control, in order to stabilize the flow, the first regulating valve is gradually closed, and when it approaches full closing, the third stage control is started.

[0011] In the third stage control, in order to stabilize the flow, when the frequency of the vacuum equipment reaches 100% of the maximum frequency, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 90 KPa to absolute vacuum, preferably 96 to 99 KPa, and the vacuum regeneration operation is stopped. At this time, the vacuum regeneration can be stopped after being delayed for 1 to 30 minutes, preferably 1 to 5 minutes.

[0012] In the present application, the adsorbent is any one of various adsorbents capable of vacuum regeneration, such as activated carbon, molecular sieve, silica gel, etc.

[0013] The present application also provides a device for the above-mentioned method for stabilizing the gas amount of vacuum regeneration, which comprises a frequency conversion vacuum equipment and a three-stage control system, pressure gauges are arranged at the inlet and outlet of the vacuum equipment, a communication side line is arranged between the pipelines in front of the inlet and outlet pressure gauges, a first regulating valve is arranged on the side line, a second regulating valve and a flow limiting device are arranged in parallel after the outlet pressure gauge, and a flow meter is arranged thereafter; wherein in the three-stage control system, the first stage control system comprises a flow meter, a second regulating valve, a flow limiting device, and a closed loop control pipeline formed by the association of the three; the second stage control system comprises a flow meter, a first regulating valve, and a closed loop control pipeline formed by the association of the two; and the third stage control system comprises a flow meter and a frequency conversion vacuum equipment, and a closed loop control pipeline formed by the association of the two.

[0014] In the present application, before starting the vacuum regeneration, the first regulating valve is opened, and the second regulating valve is closed; the first regulating valve and the second regulating valve are automatic regulating valves.

[0015] In the first stage control system, the outlet pressure of the vacuum equipment is limited by the flow limiting device, and the opening of the second regulating valve is controlled by the flow meter, so as to effectively stabilize the outlet flow. When the second regulating valve is close to full opening and still cannot maintain the set flow, the second stage control system is started.

[0016] In the second stage control system, the first regulating valve is gradually closed to stabilize the outlet flow, and when it is close to full closing, the third stage control system is started.

[0017] In the third stage control system, to stabilize the outlet flow, when the frequency of the vacuum equipment reaches 100% of the maximum frequency, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 90 KPa to absolute vacuum, preferably 96-99 KPa, and the vacuum regeneration operation is stopped. Further, the vacuum regeneration operation can be stopped after a delay of 1-30 minutes, preferably 1-5 minutes.

[0018] In the present application, the variable frequency vacuum equipment is selected from a variable frequency vacuum pump capable of generating a vacuum degree of 90 KPa to absolute vacuum, such as any one selected from but not limited to a screw vacuum pump, a liquid ring vacuum pump, a piston vacuum pump, a diaphragm vacuum pump, a rotary vane vacuum pump, etc. The variable frequency vacuum pump adjusts the vacuum pumping capacity by adjusting the frequency of the vacuum pump motor.

[0019] In the present application, the flow limiting device is a device capable of stabilizing the pressure before the regulating valve, such as any one of a process hand valve, a check valve, a pressure reducing valve, a orifice plate, etc.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] (1) During conventional vacuum regeneration operation, the gas volume fluctuation of the adsorbent using vacuum regeneration is large, which causes a large impact on the subsequent reuse device. To avoid using compression and buffer facilities, the present application uses variable frequency vacuum regeneration combined with a three-stage control method to linearize the nonlinear regeneration process to the greatest extent, ensuring the stability of the vacuum regeneration gas volume, greatly reducing the impact on the subsequent reuse device without increasing the buffer facilities.

[0022] (2) The regulating valve and the flow limiting device are connected in parallel at the outlet of the vacuum equipment, which is suitable for gas regulation under low pressure conditions. By using the flow limiting device, the pressure before the parallel regulating valve is appropriately increased, the pressure difference before and after the regulating valve is increased, and the regulating capacity of the regulating valve is increased, which helps to stabilize the outlet gas volume of the vacuum pump. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a flow diagram of the method and device of the present application.

[0024] Wherein, 1-communication side line, 2-first regulating valve, 3-vacuum pump inlet pressure gauge, 4-vacuum pump, 5-vacuum pump frequency conversion assembly, 6-vacuum pump outlet pressure gauge, 7-second regulating valve, 8-flow limiting device, 9-flow meter; 101-first level control system, 102-second level control system, 103-third level control system. DETAILED DESCRIPTION

[0025] The method and device of the present application will be further described in detail below in combination with the drawings and examples. The examples are implemented on the premise of the technical solution of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0026] In the following examples, the experimental methods are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0027] The schematic diagram of the method and device for stabilizing vacuum regeneration gas flow in the embodiment of the present application is shown in FIG. 1. Figure 1 As shown in the figure, it mainly includes a vacuum pump 4 (including a vacuum pump frequency conversion assembly 5) and a three-level control system (101, 102 and 103), an inlet pressure gauge 3 and an outlet pressure gauge 6 are respectively arranged at the inlet and outlet of the vacuum pump 4, a communication side line 1 is arranged between the pipelines in front of the inlet and outlet pressure gauges, a first regulating valve 2 is arranged on the communication side line, a second regulating valve 7 and a flow limiting device 8 are arranged in parallel after the outlet pressure gauge 6, and a flow meter 9 is arranged thereafter. In the three-level control system, the first level control system 101 mainly includes the second regulating valve 7, the flow limiting device 8, the flow meter 9 and the closed-loop control pipeline formed by the association of the three; the second level control system 102 mainly includes the first regulating valve 2, the flow meter 9 and the closed-loop control pipeline formed by the association of the two; and the third level control system 103 mainly includes the flow meter 9 and the variable frequency vacuum pump 4 and the closed-loop control pipeline formed by the association of the two.

[0028] Before the start of vacuum regeneration, the first regulating valve 2 is opened, and the second regulating valve 7 is closed.

[0029] After the start of vacuum regeneration, the three-level control system is used to control the outlet flow of the vacuum equipment to be stable.

[0030] In the first level control system, the flow limiting device 8 is used to limit the outlet pressure of the vacuum pump, and the flow meter 9 is used to control the opening degree of the second regulating valve 7, i.e. to set a predetermined flow, and the flow signal is transmitted to the second regulating valve 7 to control the opening degree, so as to effectively stabilize the outlet flow of the vacuum pump. When the second regulating valve is close to full opening and still cannot maintain the set flow, the second level control system is started.

[0031] In the second control system, the first regulating valve 2 is gradually closed by automatic control for stabilizing the outlet flow. When the first regulating valve approaches full close, the third control system is started.

[0032] In the third control system, when the vacuum pump frequency gradually reaches 100% of the maximum frequency, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 90 KPa to absolute vacuum, and the vacuum regeneration operation is stopped. Further, the vacuum regeneration operation can be stopped after being delayed for 1-30 min, preferably 1-5 min.

[0033] Example 1

[0034] The volume concentration of SO2 in the regeneration flue gas of an S Zorb device of an enterprise is 2%-5%, the volume concentration of O2 is less than 0.2%, and the flue gas treatment capacity is about 2900 Nm 3 / h. After dust removal, cooling and compression treatment, the flue gas enters the adsorption device for adsorption treatment, the adsorption pressure is 0.6 MPaG, and the adsorption time is 15 min. After adsorption, the adsorbent is regenerated by a vacuum pump, and the vacuum regeneration gas enters a downstream sulfur making device. The downstream sulfur making device requires that the flow rate be stabilized at 300-400 Nm 3 / h.

[0035] A liquid ring vacuum pump is used, and the flow limiting device is a pressure reducing valve. Before the vacuum regeneration is started, the frequency conversion of the vacuum pump motor is set to 50% of the total frequency, the initial opening of the first regulating valve is 70%, and the second regulating valve is closed. After the vacuum regeneration is started, a three-stage control mode is used to stabilize the vacuum pump outlet flow rate. The first stage control limits the vacuum pump outlet pressure to 5 KPaG through the flow limiting device, and controls the opening of the second regulating valve through the flow meter, and sets the flow rate to 348 Nm 3 / h. When the second regulating valve opening reaches 90%, and the vacuum pump outlet flow rate still cannot be stabilized, the second control is started. To stabilize the outlet flow rate, the first regulating valve is gradually closed from the initial 70% opening. When the first regulating valve approaches full close, the third control is started. To stabilize the vacuum pump outlet flow rate, the vacuum pump frequency conversion assembly gradually reaches 100% of the maximum frequency by automatic control. The vacuum degree of the vacuum pump inlet pressure gauge reaches 96 KPa, and the vacuum regeneration operation is stopped after being delayed for 2 min. The test results are shown in Table 1.

[0036] Example 2

[0037] The same as example 1, except that: before the vacuum regeneration is started, the frequency conversion of the vacuum pump motor is set to 30% of the total frequency, the initial opening of the first regulating valve is 50%, and the second regulating valve is closed. The screw vacuum pump is used, and the flow limiting device is a process hand valve. After the vacuum regeneration is started, the three-stage control mode is used to keep the outlet flow of the vacuum pump stable. The first-stage control limits the outlet pressure of the vacuum pump to 2 KPaG through the flow limiting device, and the opening of the second regulating valve is controlled through the flow meter, and the set flow is 300 Nm 3 / h; when the opening of the second regulating valve reaches 95%, the outlet flow of the vacuum pump cannot be kept at 300 Nm 3 / h, the second-stage control is started, and the first regulating valve is gradually closed from the initial opening of 50% to keep the outlet flow of the vacuum pump stable; when it is close to full closing, the third-stage control is started, and the frequency conversion assembly of the vacuum pump is gradually controlled to reach 100% of the maximum frequency to keep the outlet flow of the vacuum pump stable. The vacuum degree reaches 98 KPa, and the vacuum regeneration operation is stopped after a delay of 2 min. The detection results are shown in Table 1.

[0038] Example 3

[0039] The same as example 1, except that: before the vacuum regeneration is started, the frequency conversion of the vacuum pump motor is set to 70% of the total frequency, the initial opening of the first regulating valve is 80%, and the second regulating valve is closed. The diaphragm vacuum pump is used, and the flow limiting device is a one-way valve. After the vacuum regeneration is started, the three-stage control is used to keep the outlet flow of the vacuum pump stable. The first-stage control limits the outlet pressure of the vacuum pump to 10 KPaG through the flow limiting device, and the opening of the second regulating valve is controlled through the flow meter, and the set flow is 400 Nm 3 / h; when the opening of the second regulating valve reaches 98%, the outlet flow of the vacuum pump cannot be kept, and the second-stage control is started; to keep the outlet flow of the vacuum pump stable, the first regulating valve is gradually closed from the initial opening of 80% to full closing, and when it is close to full closing, the third-stage control is started; to keep the outlet flow of the vacuum pump stable, the frequency conversion assembly of the vacuum pump is gradually controlled to reach 100% of the maximum frequency through automatic control. The vacuum degree reaches 99 KPa, and the vacuum regeneration operation is stopped after a delay of 2 min. The detection results are shown in Table 1.

[0040] Comparative Example 1

[0041] The same as example 1, except that: the three-stage control system is not set, and the vacuum pump is directly used for conventional vacuum regeneration of the adsorbent, and the regeneration time is 15 min. The detection results are shown in Table 1.

[0042] Comparative Example 2

[0043] The same as example 1, except that: only the first-stage control and the third-stage control modes are used, and the first regulating valve and the second-stage control mode are not set. The detection results are shown in Table 1.

[0044] Comparative Example 3

[0045] The same as Example 1, except that no flow limiting device was provided in the first stage control system. The test results are shown in Table 1.

[0046] Comparative Example 4

[0047] The same as Example 1, except that no second regulating valve was provided in the first stage control system. The test results are shown in Table 1.

[0048] Comparative Example 5

[0049] The same as Example 1, except that no third stage control system was provided. The test results are shown in Table 1.

[0050] The test results of the vacuum regeneration gas volume of the different examples and comparative examples after vacuum regeneration are shown in Table 1. The vacuum regeneration temperature is room temperature.

[0051] Table 1. Change in vacuum regeneration gas volume (unit: Nm 3 / h)

[0052]

[0053] As shown in Table 1, the method of the present application can keep the gas volume within a certain range during vacuum regeneration, with less fluctuation, ensuring the stability of the vacuum regeneration gas volume, and greatly reducing the impact on the recycling device without increasing the buffer tank.

Claims

1. A method of stabilizing the vacuum regeneration gas rate, characterized by The application relates to a vacuum regeneration device for adsorbents, which comprises the following: a variable-frequency vacuum device for regenerating the adsorbents, pressure gauges arranged at the inlet and outlet of the vacuum device, a communication side line arranged between the pipelines in front of the inlet and outlet pressure gauges, a first regulating valve arranged on the side line, a second regulating valve and a flow-limiting device arranged in parallel after the outlet pressure gauge, and a flowmeter arranged after the flow-limiting device; before starting the vacuum regeneration, the first regulating valve is opened, and the second regulating valve is closed; after starting, three-stage control is adopted to keep the outlet flow stable, the first-stage control is realized by forming a closed-loop regulation and control through the flowmeter, the second regulating valve and the flow-limiting device, the outlet pressure of the vacuum device is limited to 1-30 KPaG through the flow-limiting device, the first-stage control controls the opening degree of the second regulating valve through the flowmeter, when the second regulating valve is close to full opening, i.e. the opening degree is not less than 90%, and the flow still cannot be kept, the second-stage control is started; the second-stage control is realized by forming a closed-loop regulation and control through the flowmeter and the first regulating valve, the first regulating valve is gradually closed for stable flow, when the first regulating valve is close to full closing, the third-stage control is started; the third-stage control is realized by forming a closed-loop regulation and control through the flowmeter and the vacuum device, when the frequency of the vacuum device reaches 100% of the maximum frequency, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 90 KPa to absolute vacuum, and the vacuum regeneration is stopped.

2. The method of claim 1, wherein: Before starting the vacuum regeneration, the variable-frequency of the vacuum device is set to 10%-90% of the total frequency.

3. The method of claim 2, wherein: The variable-frequency of the vacuum device is set to 40%-60% of the total frequency.

4. The method of claim 1, wherein: Before starting the vacuum regeneration, the first regulating valve is opened, and the opening degree is 10%-100%.

5. The method of claim 4, wherein: The first regulating valve is opened, and the opening degree is 60%-80%.

6. The method of claim 1, wherein: In the first-stage control, the flow-limiting device limits the outlet pressure of the vacuum device to 2-10 KPaG.

7. The method of claim 1, wherein: In the third-stage control, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 96-99 KPa, and the vacuum regeneration is stopped.

8. The method of claim 1, wherein: When the vacuum degree of the vacuum pump inlet pressure gauge reaches 90 KPa to absolute vacuum, the vacuum regeneration is stopped after a delay of 1-30 min.

9. The method of claim 7, wherein: When the vacuum degree of the vacuum pump inlet pressure gauge reaches 96-99 KPa, the vacuum regeneration is stopped after a delay of 1-5 min.

10. The method of claim 1, wherein: The adsorbents are various adsorbents which can be regenerated by the vacuum device.

11. The method of claim 10, wherein: The adsorbents are any one of activated carbon, molecular sieve and silica gel.

12. A device for the method of claim 1-11 for stabilizing the amount of vacuum regenerated gas, characterized in that The application relates to a vacuum regeneration device for adsorbents, which comprises the following: a variable-frequency vacuum device for regenerating the adsorbents, pressure gauges arranged at the inlet and outlet of the vacuum device, a communication side line arranged between the pipelines in front of the inlet and outlet pressure gauges, a first regulating valve arranged on the side line, a second regulating valve and a flow-limiting device arranged in parallel after the outlet pressure gauge, and a flowmeter arranged after the flow-limiting device; before starting the vacuum regeneration, the first regulating valve is opened, and the second regulating valve is closed; after starting, three-stage control is adopted to keep the outlet flow stable, the first-stage control is realized by forming a closed-loop regulation and control through the flowmeter, the second regulating valve and the flow-limiting device, the outlet pressure of the vacuum device is limited to 1-30 KPaG through the flow-limiting device, the first-stage control controls the opening degree of the second regulating valve through the flowmeter, when the second regulating valve is close to full opening, i.e. the opening degree is not less than 90%, and the flow still cannot be kept, the second-stage control is started; the second-stage control is realized by forming a closed-loop regulation and control through the flowmeter and the first regulating valve, the first regulating valve is gradually closed for stable flow, when the first regulating valve is close to full closing, the third-stage control is started; the third-stage control is realized by forming a closed-loop regulation and control through the flowmeter and the vacuum device, when the frequency of the vacuum device reaches 100% of the maximum frequency, the vacuum degree of the vacuum pump inlet pressure gauge is further observed to reach 90 KPa to absolute vacuum, and the vacuum regeneration is stopped.

13. The apparatus of claim 12, wherein: The first regulating valve and the second regulating valve are automatic regulating valves; before starting the vacuum regeneration, the first regulating valve is opened, and the second regulating valve is closed.

14. The apparatus of claim 12, wherein: In the first control system, the outlet pressure of the vacuum equipment is limited by the flow limiting device, and the opening of the second regulating valve is controlled by the flow meter. When the second regulating valve is close to full opening and still cannot maintain the set flow, the second control system is started.

15. The apparatus of claim 12, wherein: In the second control system, to stabilize the flow, the first regulating valve is gradually closed, and when it is close to full closing, the third control system is started.

16. The apparatus of claim 12, wherein: In the third control system, to stabilize the flow, when the frequency of the vacuum equipment reaches 100% of the maximum frequency, further observation of the vacuum degree of the vacuum pump inlet pressure gauge reaches 90KPa-absolute vacuum, and the vacuum regeneration operation is stopped.

17. The apparatus of claim 16, wherein: Further observation of the vacuum degree of the vacuum pump inlet pressure gauge reaches 96-99KPa, and the vacuum regeneration operation is stopped.

18. The apparatus of claim 12, wherein: The variable frequency vacuum equipment is selected from any one of a screw vacuum pump, a liquid ring vacuum pump, a piston vacuum pump, a diaphragm vacuum pump, and a rotary vane vacuum pump.

19. The apparatus of claim 18, wherein: The variable frequency vacuum equipment is selected from any one of a screw vacuum pump, a liquid ring vacuum pump, a piston vacuum pump, a diaphragm vacuum pump, and a rotary vane vacuum pump.

20. The apparatus of claim 12, wherein: The flow limiting device is selected from any one of a process hand valve, a check valve, a pressure reducing valve, and an orifice plate.

21. The apparatus of claim 20, wherein: The flow limiting device is selected from any one of a process hand valve, a check valve, a pressure reducing valve, and an orifice plate.

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