An online maintenance system and method for a wedge flowmeter for coking

Abstract

The present invention relates to an online maintenance system and method for a wedge flowmeter used in a coking process. The system comprises a positive pressure end purge ring, a negative pressure end purge ring, a maintenance flushing circuit, a gate valve, and a pipeline control valve. A positive pressure end purge ring and a negative pressure end purge ring are respectively provided at the flange connections between the front and rear pressure taking tubes and a double-flange differential pressure transmitter. The positive pressure end purge ring and the negative pressure end purge ring are both used to connect to the maintenance flushing circuit. The maintenance flushing circuit is provided with a pipeline control valve. The gate valve is provided on the measuring tube at the front end of the wedge flowmeter body. The gate valve and the pipeline control valve are connected to a PLC / DCS system. The advantages of the present invention are: it changes the traditional offline maintenance method and provides a gate valve with adjustable opening, a purge ring, a maintenance flushing circuit, and a pipeline control valve on the basis of a conventional wedge flowmeter, thereby realizing online and offline maintenance; it provides an online automatic maintenance mode and an offline automatic maintenance mode, thereby expanding the scope of application of the wedge flowmeter's online maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of flow meter measurement in the coking industry, and in particular to an online maintenance system and method for a wedge-shaped flow meter used in coking. Background Art

[0002] Wedge flowmeters are widely used in gas purification units in the coking industry to measure process media flow, primarily for liquid flow measurement of tar-containing media. Because the media contains tar, crude benzene, naphthalene, ammonia, and oil residue, selecting a flow measurement instrument becomes difficult. In this case, a wedge flowmeter paired with a double-flange transmitter is often used. This method can reduce the problem of inaccurate measurements caused by contaminated media. However, due to the double-flange pressure measurement method, the liquid pressure measurement requires a bottom-mounted flange transmitter (liquid below, gas above). This often causes the pressure pipe to become clogged with a mixture of contaminated tar, naphthalene, and oil residue, affecting the wedge flowmeter's accurate measurement and frequently requiring maintenance personnel to remove it for cleaning. This offline maintenance method can affect the operating rate of the gas purification unit and, in severe cases, require production suspension for maintenance.

[0003] The traditional maintenance method of wedge flowmeter for coking has the following problems:

[0004] 1. Due to the characteristics of tar and other dirty media in the gas purification device in the coking industry, wedge flowmeters often make inaccurate measurements, and the failure rate of the instrument is very high. Maintenance of the instrument system becomes indispensable, with heavy workload and low efficiency.

[0005] 2. The traditional maintenance method is offline, which requires the instrument to stop working, be disassembled and flushed offline, affecting the continuous production of the process, increasing labor maintenance costs and low work efficiency. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide an online maintenance system and method for a wedge flowmeter for coking, which is equipped with a gate valve with adjustable opening, a purge ring, a maintenance flushing circuit and a pipeline control valve on the traditional wedge flowmeter to achieve online maintenance.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] An online maintenance system for a wedge-shaped flowmeter for coking includes a wedge-shaped flowmeter, which includes a double-flange differential pressure transmitter, a front pressure-taking tube, a rear pressure-taking tube, a positive pressure end capillary, a negative pressure end capillary, and a wedge-shaped flowmeter body. The front pressure-taking tube is used to connect to the positive pressure end of the double-flange differential pressure transmitter through the positive pressure end capillary, and the rear pressure-taking tube is used to connect to the negative pressure end of the double-flange differential pressure transmitter through the negative pressure end capillary. Both the positive pressure end and the negative pressure end of the double-flange differential pressure transmitter adopt a diaphragm to take pressure. The wedge-shaped flowmeter body is arranged at The process pipeline also includes a positive pressure end purge ring, a negative pressure end purge ring, a maintenance flushing circuit, a gate valve, and a pipeline control valve. The flange connections between the front pressure taking pipe and the rear pressure taking pipe and the double flange differential pressure transmitter are respectively provided with a positive pressure end purge ring and a negative pressure end purge ring. Both the positive pressure end purge ring and the negative pressure end purge ring are used to connect the maintenance flushing circuit. The maintenance flushing circuit is provided with a pipeline control valve. The gate valve is provided on the measuring tube at the front end of the wedge flowmeter body. The gate valve and the pipeline control valve are connected to the PLC / DCS system through ports.

[0009] The maintenance flushing circuit includes a sewage pipe and a purge pipe. The purge pipe includes purge pipe 1, purge pipe 2, and purge pipe 3. One end of purge pipe 1 is connected to the positive pressure end purge ring, and the other end of purge pipe 1 is connected to the negative pressure end purge ring. Purge pipe 2 and purge pipe 3 are connected to purge pipe 1, the other end of purge pipe 2 is connected to the measuring tube, and the other end of purge pipe 3 is used to pass back-flushing steam. A plurality of purge holes are provided on the positive pressure end purge ring and the negative pressure end purge ring, which are connected to the purge pipe and sewage pipe through pipelines.

[0010] The pipeline control valve includes a positive pressure end purge valve, a negative pressure end purge valve, an E zone purge valve, a steam purge valve, a positive pressure end steam backblowing drain valve, and a negative pressure end steam backblowing drain valve. The positive pressure end purge valve and the negative pressure end purge valve are sequentially arranged on the purge pipe one, the E zone purge valve is arranged on the purge pipe two, and the steam purge valve is arranged on the purge pipe three. The positive pressure end purge ring is connected to the positive pressure end steam backblowing drain valve through a drain pipe, and the negative pressure end purge ring is connected to the negative pressure end steam backblowing drain valve through a drain pipe.

[0011] The wedge flowmeter body includes a wedge block and a measuring tube. The wedge block is arranged in the measuring tube, and the measuring tube is connected to the process pipeline through a flange.

[0012] An online maintenance method for a wedge flowmeter used in a coking plant adjusts the opening of a gate valve so that the pressure differential across the gate valve acts as a driving force, causing the medium in the area of the wedge flowmeter where dirty media accumulate to flow. The flow of the medium itself creates self-flushing, thereby achieving automatic maintenance of the wedge flowmeter. The self-flushing of the area where dirty media accumulates is remotely controlled via a PLC / DCS system. The remote control includes both online and offline automatic maintenance modes, and the maintenance mode is selected via the HMI human-machine interface.

[0013] The areas where dirty media gather in the wedge flowmeter include the differential pressure transmitter diaphragm area of the front pressure taking pipe in area A, the differential pressure transmitter diaphragm area of the rear pressure taking pipe in area B, the low flow velocity area of the throttling effect of the gate valve in area C, the low flow velocity area at the front end of the wedge block of the wedge flowmeter in area D, and the low flow velocity area at the rear end of the wedge block of the wedge flowmeter in area E.

[0014] The online automatic maintenance mode is a maintenance mode that is performed without stopping the process production, including the online gate valve maintenance mode and the online steam automatic backflush mode;

[0015] The online gate valve maintenance mode uses the medium itself for flushing. It is used to adjust the opening of the gate valve to generate sufficient differential pressure at the front and rear pressure points of the wedge flowmeter when backwash steam is not allowed to enter the process medium. By controlling the positive pressure end purge valve, negative pressure end purge valve, and E zone purge valve, the process medium is allowed to flow freely, completing the online maintenance of the area where the dirty medium accumulates in the wedge flowmeter.

[0016] The online steam automatic backflush mode is used for working conditions where the pressure of the process medium is lower than the steam pressure. When backflush steam is allowed to enter the process medium, the positive pressure end purge valve, negative pressure end purge valve, E zone purge valve and steam purge valve are controlled to allow the area where dirty media accumulates in the wedge flowmeter to be purged by backflush steam, so that the dirty media is dissolved and removed by steam.

[0017] The offline automatic maintenance mode is when the process production is shut down for maintenance and the process medium is in an empty state. The steam backflush method is used for maintenance. The dirty medium generated by the backflush is discharged through the control of the steam backflush drain valve at the positive pressure end and the steam backflush drain valve at the negative pressure end of the drain pipe.

[0018] Remote control is achieved by the PLC / DCS system, including the following

[0019] (1) Select the online gate valve maintenance mode to implement the maintenance of areas A, B, C, and D. The steps are as follows:

[0020] 1) Initial state of pipeline control valve: close the steam purge valve, close the steam backflush drain valve at the positive pressure end, and close the steam backflush drain valve at the negative pressure end;

[0021] 2) Control the opening of the gate valve to K, where K is given by the process through the HMI human-machine interface;

[0022] 3) Open the purge valve on the positive pressure side, close the purge valve on the negative pressure side, and open the purge valve in zone E;

[0023] 4) Rinse areas A, D, and E;

[0024] 5) Duration T1, T1 is given by the process through the HMI human-machine interface;

[0025] 6) Open the purge valve on the positive pressure side, open the purge valve on the negative pressure side, and close the purge valve in zone E;

[0026] 7) Rinse areas A, B, and D;

[0027] 8) Duration T2, T2 is given by the process through the HMI human-machine interface;

[0028] 9) Control the gate valve to fully open;

[0029] 10) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve;

[0030] (2) Select the online steam automatic backflush mode to implement maintenance of areas A, B, and D. The steps are as follows:

[0031] 1) Initial state control of pipeline control valve:

[0032] Control the gate valve to fully open.

[0033] Close the steam purge valve, close the steam backflush drain valve at the positive pressure end, and close the steam backflush drain valve at the negative pressure end;

[0034] 2) Open the steam purge valve, open the positive pressure end purge valve, close the negative pressure end purge valve, and close the E zone purge valve;

[0035] 3) Clean area A;

[0036] 4) Duration T3, T3 is given by the process through the HMI human-machine interface;

[0037] 5) Open the steam purge valve, close the positive pressure end purge valve, open the negative pressure end purge valve, and close the E zone purge valve;

[0038] 6) Clean area B;

[0039] 7) Duration T4, T4 is given by the process through the HMI human-machine interface;

[0040] 8) Open the steam purge valve, close the positive pressure end purge valve, close the negative pressure end purge valve, and open the E zone purge valve;

[0041] 9) Cleaning of area E;

[0042] 10) Duration T5, T5 is given by the process through the HMI human-machine interface;

[0043] 11) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve.

[0044] (3) Select offline automatic maintenance mode, the steps are as follows:

[0045] 1) Open the steam purge valve, open the positive pressure end purge valve, open the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve;

[0046] 2) Clean area A;

[0047] 3) Duration T3, given by the process through the HMI human-machine interface;

[0048] 4) Open the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, open the negative pressure end purge valve, close the E zone purge valve, and open the negative pressure end steam backflush drain valve;

[0049] 5) Clean area B;

[0050] 6) Duration T4, T4 is given by the process through the HMI human-machine interface;

[0051] 7) Cleaning of area E;

[0052] 8) Open the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush valve, close the negative pressure end purge valve, open the E zone purge valve, open the negative pressure end steam backflush valve

[0053] 9) Duration T5, T5 is given by the process through the HMI human-machine interface;

[0054] 10) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1. Change the traditional offline maintenance method and set an adjustable gate valve, purge ring, maintenance flushing circuit and pipeline control valve on the basis of the traditional wedge flowmeter to achieve online and offline maintenance;

[0057] 2. Provides online automatic maintenance mode and offline automatic maintenance mode, operators can choose according to the actual situation on site, which improves the applicability of wedge flowmeter online maintenance;

[0058] 3. Operators can check the equipment operating status at any time through the HMI human-machine interface;

[0059] 4. Through simple transformation of traditional wedge flowmeter, it is easy to operate and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a structural diagram of the online maintenance system for wedge flowmeters used in coking.

[0061] Figure 2 This is a flow chart of the online maintenance method for wedge flowmeters used in coking.

[0062] Figure 3 This is a schematic diagram of the principle of the online maintenance method of the wedge flowmeter used in coking.

[0063] In the figure: 1-front pressure taking pipe 2-rear pressure taking pipe 3-positive pressure end of double flange differential pressure transmitter 4-negative pressure end of double flange differential pressure transmitter 5-positive pressure end capillary 6-negative pressure end capillary 7-positive pressure end purge ring 8-negative pressure end purge ring 9-double flange differential pressure transmitter 10-wedge block 11-gate valve 12-backflush nozzle 13-positive pressure end purge valve 14-negative pressure end purge valve 15-E zone purge valve 16-steam purge valve 17-positive pressure end steam backflush drain valve 18-negative pressure end steam backflush drain valve 19-automatic maintenance mode selection module 20-online automatic maintenance mode pre-processing module 21-online gate valve maintenance module 22-online steam automatic backflush module 23-online automatic maintenance mode post-processing module 24-offline automatic maintenance module 25-measuring tube 26-purge pipe one 27-purge pipe three 28-purge pipe two DETAILED DESCRIPTION

[0064] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0065] The following examples are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0066] [Example 1]

[0067] See Figure 1 , Figure 2 , Figure 3The wedge flowmeter used in the gas purification device of the coking industry is mainly used to measure the liquid flow of tar-containing media. Dirty media tend to accumulate in the stagnant area or low flow area of the wedge flowmeter, thus affecting the normal measurement of the wedge flowmeter. The online maintenance method is to clean the dirty media area online, so that the maintenance of the wedge flowmeter can be completed without stopping the process. Figure 3 Area A is the diaphragm area of the differential pressure transmitter of the front pressure taking pipe, and area B is the diaphragm area of the differential pressure transmitter of the rear pressure taking pipe. When the wedge flowmeter is working, the media in areas A and B are in a static state and are in the low end area of the wedge flowmeter, which is the main gathering place of dirty media; area E at the rear end of the wedge block 10 of the wedge flowmeter is the low flow velocity area of the wedge flowmeter and is also the gathering place of dirty media; if area D at the front end of the wedge body with a relatively low flow velocity is not maintained for a long time, dirt will also accumulate. The maintenance work is to automatically clean and maintain areas A, B and E in the figure, while taking into account the cleaning and maintenance of area D.

[0068] The online maintenance method involves installing an adjustable gate valve 11 at the front end of the wedge of a conventional coking wedge flowmeter. A purge ring is added to the flanges of the front and rear pressure pipes 2. The purge ring has multiple purge holes, which are connected to the purge pipe and the sewage pipe via pipelines. The purge pipe is used to connect the front and rear pressure pipes 2. A pipeline control valve is installed on the purge pipe, and a steam backflush interface is installed in the middle of the purge pipe. One method is to allow the medium to flow at the point where the dirty medium in the pressure pipe accumulates, that is, at the diaphragm of the double-flange differential pressure transmitter 9. By adjusting the opening of the gate valve 11, the medium in the purge pipe flows, flushing the accumulated dirty medium away from the measured medium itself. Another method is to use steam backflush maintenance to purge the area where the dirty medium accumulates. Since the main components of the medium are a mixture of tar, crude benzene, naphthalene, ammonia water, and oil residue, these media will be dissolved by the steam, thereby clearing the dirty medium.

[0069] A wedge flowmeter online maintenance system for coking includes a wedge flowmeter, which includes a double-flange differential pressure transmitter 9, a front pressure-taking pipe 1, a rear pressure-taking pipe 2, a positive-pressure end capillary 5, a negative-pressure end capillary 6, a wedge flowmeter body, a positive-pressure end purge ring 7, a negative-pressure end purge ring 8, a maintenance flushing circuit, a gate valve 11, and a pipeline control valve. The wedge flowmeter body adopts a pipe segment installation structure and is connected to the process pipeline through a flange installation method. The wedge flowmeter body includes a wedge block 10 and a measuring tube 25. The wedge block 10 is arranged in the measuring tube 25, and the front pressure-taking pipe 1 and the rear pressure-taking pipe 2 are respectively connected to the measuring tube 25.

[0070] The front pressure-taking tube 1 is used to connect the positive pressure end 3 of the double-flange differential pressure transmitter through the positive pressure end capillary 5, and the rear pressure-taking tube 2 is used to connect the negative pressure end 4 of the double-flange differential pressure transmitter through the negative pressure end capillary 6. The positive pressure end 3 and the negative pressure end 4 of the double-flange differential pressure transmitter are both pressure-taken by diaphragms. The wedge-shaped flowmeter body is set on the process pipeline. The flange connections between the front pressure-taking tube 1 and the rear pressure-taking tube 2 and the double-flange differential pressure transmitter 9 are respectively provided with positive pressure end purge rings 7 and negative pressure end purge rings. Ring 8, the positive pressure end purge ring 7 and the negative pressure end purge ring 8 are all used to connect the maintenance flushing circuit. The maintenance flushing circuit is provided with a pipeline control valve. The control valve adopts a cut-off valve. The cut-off valve can be pneumatically driven or electrically driven. The gate valve 11 is arranged on the measuring tube 25 at the front end of the wedge flowmeter body. The inner diameter of the gate valve 11 is consistent with the inner diameter of the wedge flowmeter. The gate valve 11 and the pipeline control valve are connected to the PLC / DCS system and controlled by the PLC / DCS system.

[0071] The maintenance flushing circuit includes a sewage pipe and a purge pipe. The purge pipe includes purge pipe 1 26, purge pipe 2 28, and purge pipe 3 27. One end of purge pipe 1 26 is connected to the positive pressure end purge ring 7, and the other end of purge pipe 1 26 is connected to the negative pressure end purge ring 8. Purge pipe 2 28 and purge pipe 3 27 are connected to purge pipe 1 26. The other end of purge pipe 2 28 is connected to the measuring tube 25. A back-blowing nozzle 12 is provided at the connection between the other end of purge pipe 28 and the measuring tube 25 for purging the E zone of the wedge flowmeter. The other end of purge pipe 3 27 is used for introducing back-blowing steam. A plurality of purge holes are provided on the positive pressure end purge ring and the negative pressure end purge ring, which are connected to the purge pipe and sewage pipe through pipelines.

[0072] The pipeline control valve includes a positive pressure end purge valve 13, a negative pressure end purge valve 14, an E zone purge valve 15, a steam purge valve 16, a positive pressure end steam backblowing drain valve 17, and a negative pressure end steam backblowing drain valve 18. The positive pressure end purge valve 13 and the negative pressure end purge valve 14 are sequentially arranged on the purge pipe 1 26, the E zone purge valve 15 is arranged on the purge pipe 2 28, and the steam purge valve 16 is arranged on the purge pipe 3 27. The positive pressure end purge ring 7 is connected to the positive pressure end steam backblowing drain valve 17 through a drain pipe, and the negative pressure end purge ring 8 is connected to the negative pressure end steam backblowing drain valve 18 through a drain pipe.

[0073] The online maintenance method for the wedge flowmeter used in coking adjusts the opening of the gate valve 11 so that the pressure difference generated before and after the gate valve 11 acts as a driving force, causing the medium in the area where the dirty medium accumulates in the wedge flowmeter to flow. The flow of the medium itself creates an automatic flushing effect, thus achieving automatic maintenance of the wedge flowmeter. The self-flushing control of the area where the dirty medium accumulates is achieved through the remote control of the gate valve 11 and the pipeline control valve through the PLC / DCS system. The remote control includes online automatic maintenance mode and offline automatic maintenance mode. The online automatic maintenance mode and offline automatic maintenance mode are selected through the HMI human-machine interface of the PLC / DCS system. The online automatic maintenance mode includes online gate valve 11 maintenance mode and online steam automatic backflush mode.

[0074] The online gate valve 11 maintenance mode utilizes the medium itself for flushing. When backwash steam is not allowed to enter the process medium, the gate valve 11 is opened to generate a sufficient differential pressure at the front and rear pressure points of the wedge flowmeter. By controlling the positive pressure end purge valve 13, the negative pressure end purge valve 14, and the E zone purge valve 15, the process medium is allowed to flow freely, completing the online maintenance mode of the wedge flowmeter in the area where the dirty medium accumulates.

[0075] The online steam automatic backflush mode is used for the working condition where the pressure of the process medium is lower than the steam pressure. When backflush steam is allowed to enter the process medium, the positive pressure end purge valve 13, the negative pressure end purge valve 14, the E zone purge valve 15 and the steam purge valve 16 are controlled to allow the area where the dirty medium of the wedge flowmeter accumulates to be purged by the backflush steam, so that the dirty medium is dissolved and removed by the steam.

[0076] The offline automatic maintenance mode uses steam backflush for maintenance. Since the process medium is in an empty state, the dirty medium generated by backflush is discharged by controlling the positive pressure end steam backflush drain valve 17 and the negative pressure end steam backflush drain valve 18 on the drain pipe.

[0077] When the flow meter is working normally, the gate valve 11 is in the fully open state. When the flow meter needs to be maintained, the gate valve 11 controls the opening to H, which is given by the HMI human-machine interface. At this time, a sufficient pressure difference will be generated at the front and rear pressure-taking parts of the wedge flow meter. At this time, by controlling the positive-pressure end purge valve 13, the negative-pressure end purge valve 14, and the E-zone purge valve 15 on the purge pipe, the medium in the purge pipe will produce continuous flow, thereby achieving maintenance and cleaning of areas A, B, and E where the dirty media of the wedge flow in the coking industry gather. At the same time, due to the throttling effect of the gate valve 11, the fluid in area C of the wedge body is compressed, and the flow velocity in the local area increases, so that area D at the front end of the wedge body is also maintained and cleaned.

[0078] A back-blowing steam interface is provided on the purge pipeline. The steam is derived from a heat source medium commonly used in the gas purification area of the coking industry. A steam purge valve 16 is provided at the back-blowing steam input end. A positive-pressure steam back-blowing drain valve 17 and a negative-pressure steam back-blowing drain valve 18 are provided on the positive-pressure purge ring and the negative-pressure purge ring, respectively. By controlling the positive-pressure purge valve 13, the negative-pressure purge valve 14, the E-zone purge valve 15, the steam purge valve 16, the positive-pressure steam back-blowing drain valve 17, and the negative-pressure steam back-blowing drain valve 18, steam cleaning of the pipeline is achieved, and automatic online and offline maintenance is performed on Zones A, B, and E, where wedge-shaped flow contaminated media accumulate in the coking industry. The gate valve 11, the positive pressure end purge valve 13, the negative pressure end purge valve 14, the E zone purge valve 15, the steam purge valve 16, the positive pressure end steam backflush drain valve 17, and the negative pressure end steam backflush drain valve 18 are all remotely controlled by the existing gas purification PLC / DCS system.

[0079] [Example 2]

[0080] See Figure 2 The maintenance method is achieved by adding a maintenance program to the gas purification PLC / DCS system. The operation station is equipped with an HMI human-machine interface. The setting values of parameters and the selection of maintenance mode are operated by the operator through the HMI human-machine interface. The contents include the following:

[0081] (1) Automatic maintenance mode selection module 19

[0082] 1) Select the maintenance start mode, including timed start or manual start;

[0083] 2) Set the timed start maintenance cycle T0, which is given by the HMI human-machine interface;

[0084] 3) Select the maintenance mode, including online automatic maintenance mode and offline automatic maintenance mode. The online automatic maintenance mode is maintenance performed through the automatic maintenance program when the process production is not stopped. The offline automatic maintenance mode is maintenance performed when the medium in the pipeline has been drained when the process is stopped for maintenance;

[0085] (2) Online automatic maintenance mode pre-processing module 20

[0086] 1) Start the online maintenance program;

[0087] 2) Flow maintenance;

[0088] 3) Select online maintenance mode:

[0089] Online gate valve 11 maintenance mode;

[0090] Online steam backflush mode.

[0091] (3) Online gate valve 11 maintenance module 21

[0092] This method is used when backwash steam is not allowed to enter the process medium and the online steam backwash maintenance mode cannot be used. In this case, the opening of the gate valve 11 is changed to achieve the self-flow of the process medium to complete the online maintenance method of the wedge flowmeter. This method uses the medium itself for flushing and does not require external maintenance medium to achieve maintenance of areas A, B, C, and D. The steps are as follows:

[0093] 1) Initial state of pipeline control valve: close steam purge valve 16, close steam backflush drain valve 17 at positive pressure end, and close steam backflush drain valve 18 at negative pressure end;

[0094] 2) Control the opening of the gate valve 11 to K, where K is given by the process through the HMI human-machine interface;

[0095] 3) Open the purge valve 13 on the positive pressure side, close the purge valve 14 on the negative pressure side, and open the purge valve 15 in zone E;

[0096] 4) Rinse areas A, D, and E;

[0097] 5) Duration T1, T1 is given by the process through the HMI human-machine interface;

[0098] 6) Open the purge valve 13 on the positive pressure side, open the purge valve 14 on the negative pressure side, and close the purge valve 15 in zone E;

[0099] 7) Rinse areas A, B, and D;

[0100] 8) Duration T2, T2 is given by the process through the HMI human-machine interface;

[0101] 9) Control the gate valve 11 to fully open;

[0102] 10) Close the steam purge valve 16, close the positive pressure end purge valve 13, close the positive pressure end steam backflush drain valve 17, close the negative pressure end purge valve 14, close the E zone purge valve 15, and close the negative pressure end steam backflush drain valve 18;

[0103] (IV) Online steam automatic backflush module 22

[0104] This maintenance mode utilizes steam online backflush when backflush steam is allowed to enter the process medium. The process medium pressure must be much lower than the steam pressure to ensure smooth steam purge. Maintenance of areas A, B, and D is achieved by flushing with steam. The steps are as follows:

[0105] 1) Initial state control of pipeline control valve:

[0106] Control the gate valve 11 to fully open;

[0107] Close the steam purge valve 16, close the positive pressure end steam backflush drain valve 17, and close the negative pressure end steam backflush drain valve 18;

[0108] 2) Open the steam purge valve 16, open the positive pressure end purge valve 13, close the negative pressure end purge valve 14, and close the E zone purge valve 15;

[0109] 3) Clean area A;

[0110] 4) Duration T3, T3 is given by the process through the HMI human-machine interface;

[0111] 5) Open the steam purge valve 16, close the positive pressure end purge valve 13, open the negative pressure end purge valve 14, and close the E zone purge valve 15;

[0112] 6) Clean area B;

[0113] 7) Duration T4, T4 is given by the process through the HMI human-machine interface;

[0114] 8) Open the steam purge valve 16, close the positive pressure end purge valve 13, close the negative pressure end purge valve 14, and open the E zone purge valve 15;

[0115] 9) Cleaning of area E;

[0116] 10) Duration T5, T5 is given by the process through the HMI human-machine interface;

[0117] (V) Online automatic maintenance mode post-processing module 23

[0118] 1) Close the steam purge valve 16, close the positive pressure end purge valve 13, close the positive pressure end steam backflush drain valve 17, close the negative pressure end purge valve 14, close the E zone purge valve 15, and close the negative pressure end steam backflush drain valve 18;

[0119] 2) Restore flow measurement;

[0120] Online automatic maintenance ends;

[0121] (6) Offline automatic maintenance module 24

[0122] The offline automatic maintenance mode uses steam backflush for maintenance. Since the process medium is in an empty state, the dirty medium generated by backflush cannot flow out with the process medium. Therefore, a sewage pipe is set at the front and rear purge rings. The discharge of the dirty medium is controlled by the control valve on the sewage pipe. The steps are as follows:

[0123] 1) Open the steam purge valve 16, open the positive pressure end purge valve 13, open the positive pressure end steam backflush drain valve 17, close the negative pressure end purge valve 14, close the E zone purge valve 15, and close the negative pressure end steam backflush drain valve 18;

[0124] 2) Clean area A;

[0125] 3) Duration T3, given by the process through the HMI human-machine interface;

[0126] 4) Open the steam purge valve 16, close the positive pressure end purge valve 13, close the positive pressure end steam backflush drain valve 17, open the negative pressure end purge valve 14, close the E zone purge valve 15, and open the negative pressure end steam backflush drain valve 18;

[0127] 5) Clean area B;

[0128] 6) Duration T4, T4 is given by the process through the HMI human-machine interface;

[0129] 7) Cleaning of area E;

[0130] 8) Open the steam purge valve 16, close the positive pressure end purge valve 13, close the positive pressure end steam backflush drain valve 17, close the negative pressure end purge valve 14, open the E zone purge valve 15, and open the negative pressure end steam backflush drain valve 18;

[0131] 9) Duration T5, T5 is given by the process through the HMI human-machine interface;

[0132] 10) Close the steam purge valve 16, close the positive pressure end purge valve 13, close the positive pressure end steam backflush drain valve 17, close the negative pressure end purge valve 14, close the E zone purge valve 15, and close the negative pressure end steam backflush drain valve 18;

[0133] 11) Offline automatic maintenance is completed.

[0134] (7) Parameter setting

[0135] In the above description:

[0136] T1 - the flushing maintenance time of area A, area D and area E in the maintenance mode of online gate valve 11;

[0137] T2 - the flushing maintenance time of area A, area B and area D in the maintenance mode of online gate valve 11;

[0138] T3 - the time for maintaining the flushing maintenance state of area A in steam backwash mode;

[0139] T4--The flushing maintenance time of zone B in steam backwash mode;

[0140] T5--The flushing maintenance time of zone E in steam backwash mode;

[0141] H--Control the opening of gate valve 11 during maintenance.

[0142] The above-mentioned time is set by the operating personnel through the HMI human-machine interface on the gas purification control system, and is determined according to the specifications, medium conditions and maintenance results of the wedge flowmeter. It is continuously corrected during use to ensure that the wedge flowmeter can meet normal measurement requirements after maintenance.

[0143] (8) Flow measurement and processing during maintenance

[0144] During the online maintenance of the wedge flowmeter, the flow measurement is maintained in consideration of the deviation caused by the maintenance process, and the flow measurement is restored after the maintenance is completed.

[0145] The present invention changes the traditional offline maintenance method and provides a gate valve with adjustable opening, a purge ring, a maintenance flushing circuit and a pipeline control valve on the basis of a conventional wedge flowmeter to realize online maintenance and offline maintenance; it provides an online automatic maintenance mode and an offline automatic maintenance mode, and the operator can optimize the mode according to the actual situation on site, thereby improving the applicability of the online maintenance of the wedge flowmeter.

Claims

1. A method for online maintenance of a wedge-shaped flowmeter for coking, and an online maintenance system for a wedge-shaped flowmeter for coking to implement the method, comprising a wedge-shaped flowmeter, the wedge-shaped flowmeter comprising a double-flange differential pressure transmitter, a front pressure-taking tube, a rear pressure-taking tube, a positive-pressure end capillary tube, a negative-pressure end capillary tube, and a wedge-shaped flowmeter body. The front pressure-taking tube is used to connect to the positive-pressure end of the double-flange differential pressure transmitter via the positive-pressure end capillary tube, and the rear pressure-taking tube is used to connect to the negative-pressure end of the double-flange differential pressure transmitter via the negative-pressure end capillary tube. Both the positive-pressure end and the negative-pressure end of the double-flange differential pressure transmitter use diaphragms to take pressure. The wedge-shaped flowmeter body is arranged on the process pipeline, and also includes a positive pressure end purge ring, a negative pressure end purge ring, a maintenance flushing circuit, a gate valve, and a pipeline control valve. The flange connections between the front pressure taking pipe and the rear pressure taking pipe and the double-flange differential pressure transmitter are respectively provided with a positive pressure end purge ring and a negative pressure end purge ring. Both the positive pressure end purge ring and the negative pressure end purge ring are used to connect the maintenance flushing circuit. The maintenance flushing circuit is provided with a pipeline control valve. The gate valve is arranged on the measuring pipe at the front end of the wedge-shaped flowmeter body. The gate valve and the pipeline control valve are connected to the PLC / DCS system through ports; it is characterized in that, By adjusting the opening of the gate valve, the pressure differential across the gate valve acts as a driving force, causing the medium in the area of the wedge flowmeter where dirty media accumulate to flow. This flow of the medium itself creates self-flushing, enabling automatic maintenance of the wedge flowmeter. Remote control of the self-flushing in the area where dirty media accumulate is achieved through the PLC / DCS system. Remote control includes both online and offline automatic maintenance modes, and the maintenance mode can be selected through the HMI. The online automatic maintenance mode is a maintenance mode performed without stopping the process production, including an online gate valve maintenance mode and an online steam automatic backflush mode; The online gate valve maintenance mode uses the medium itself for flushing. It is used to adjust the opening of the gate valve to generate sufficient differential pressure at the front and rear pressure points of the wedge flowmeter when backwash steam is not allowed to enter the process medium. By controlling the positive pressure end purge valve, negative pressure end purge valve, and E zone purge valve, the process medium is allowed to flow freely, completing the online maintenance of the area where the dirty medium accumulates in the wedge flowmeter. The online steam automatic backflush mode is used for working conditions where the pressure of the process medium is lower than the steam pressure. When backflush steam is allowed to enter the process medium, the positive pressure end purge valve, negative pressure end purge valve, E zone purge valve, and steam purge valve are controlled to allow the area where the dirty medium of the wedge flowmeter accumulates to be purged by the backflush steam, so that the dirty medium is dissolved and removed by the steam. Remote control is achieved by the PLC / DCS system, including the following (1) Select the online gate valve maintenance mode to implement the maintenance of areas A, B, C, and D. The steps are as follows: 1) Initial state of pipeline control valve: close the steam purge valve, close the steam backflush drain valve at the positive pressure end, and close the steam backflush drain valve at the negative pressure end; 2) Control the opening of the gate valve to K, which is given by the process through the HMI human-machine interface; 3) Open the purge valve on the positive pressure side, close the purge valve on the negative pressure side, and open the purge valve in zone E; 4) Rinse areas A, D and E; 5) Duration T1, T1 is given by the process through the HMI human-machine interface; 6) Open the purge valve on the positive pressure side, open the purge valve on the negative pressure side, and close the purge valve in zone E; 7) Rinse areas A, B and D; 8) Duration T2, T2 is given by the process through the HMI human-machine interface; 9) Control the gate valve to fully open; 10) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve; (2) Select the online steam automatic backflush mode to perform maintenance on areas A, B, and D. The steps are as follows: 1) Initial state control of pipeline control valve: Control the gate valve to fully open; Close the steam purge valve, close the steam backflush drain valve at the positive pressure end, and close the steam backflush drain valve at the negative pressure end; 2) Open the steam purge valve, open the positive pressure end purge valve, close the negative pressure end purge valve, and close the E zone purge valve; 3) Clean area A; 4) Duration T3, T3 is given by the process through the HMI human-machine interface; 5) Open the steam purge valve, close the positive pressure end purge valve, open the negative pressure end purge valve, and close the E zone purge valve; 6) Clean area B; 7) Duration T4, T4 is given by the process through the HMI human-machine interface; 8) Open the steam purge valve, close the positive pressure end purge valve, close the negative pressure end purge valve, and open the E zone purge valve; 9) Clean area E; 10) Duration T5, T5 is given by the process through the HMI human-machine interface; 11) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve; (3) Select offline automatic maintenance mode, the steps are as follows: 1) Open the steam purge valve, open the positive pressure end purge valve, open the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve; 2) Clean area A; 3) Duration T3, given by the process through the HMI human-machine interface; 4) Open the steam purge valve, close the purge valve at the positive pressure end, close the steam backflush valve at the positive pressure end, open the purge valve at the negative pressure end, close the purge valve in zone E, and open the steam backflush valve at the negative pressure end; 5) Clean area B; 6) Duration T4, T4 is given by the process through the HMI human-machine interface; 7) Clean area E; 8) Open the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, open the E zone purge valve, and open the negative pressure end steam backflush drain valve; 9) Duration T5, T5 is given by the process through the HMI human-machine interface; 10) Close the steam purge valve, close the positive pressure end purge valve, close the positive pressure end steam backflush drain valve, close the negative pressure end purge valve, close the E zone purge valve, and close the negative pressure end steam backflush drain valve; The areas where dirty media gather in the wedge-shaped flowmeter include the differential pressure transmitter diaphragm area of the front pressure-taking pipe in area A, the differential pressure transmitter diaphragm area of the rear pressure-taking pipe in area B, the low flow velocity area of the throttling effect of the gate valve in area C, the low flow velocity area at the front end of the wedge block of the wedge flowmeter in area D, and the low flow velocity area at the rear end of the wedge block of the wedge flowmeter in area E.

2. The online maintenance method for a wedge flowmeter for coking according to claim 1, characterized in that: The maintenance flushing circuit includes a sewage pipe and a purge pipe. The purge pipe includes purge pipe 1, purge pipe 2, and purge pipe 3. One end of purge pipe 1 is connected to the positive-pressure end purge ring, and the other end of purge pipe 1 is connected to the negative-pressure end purge ring. Purge pipe 2 and purge pipe 3 are connected to purge pipe 1, the other end of purge pipe 2 is connected to the measuring tube, and the other end of purge pipe 3 is used to pass back-blowing steam. A plurality of purge holes are provided on the positive-pressure end purge ring and the negative-pressure end purge ring, which are connected to the purge pipe and the sewage pipe through pipelines.

3. The online maintenance method of a wedge flowmeter for coking according to claim 1, characterized in that: The pipeline control valve includes a positive pressure end purge valve, a negative pressure end purge valve, an E zone purge valve, a steam purge valve, a positive pressure end steam backblowing drain valve, and a negative pressure end steam backblowing drain valve. The positive pressure end purge valve and the negative pressure end purge valve are sequentially arranged on the purge pipe one, the E zone purge valve is arranged on the purge pipe two, and the steam purge valve is arranged on the purge pipe three. The positive pressure end purge ring is connected to the positive pressure end steam backblowing drain valve through a drain pipe, and the negative pressure end purge ring is connected to the negative pressure end steam backblowing drain valve through a drain pipe.

4. The online maintenance method for a wedge flowmeter for coking according to claim 1, characterized in that: The wedge-shaped flowmeter body comprises a wedge-shaped block and a measuring tube. The wedge-shaped block is arranged in the measuring tube, and the measuring tube is connected to the process pipeline through a flange.

5. The online maintenance method for a wedge flowmeter for coking according to claim 1, characterized in that: The offline automatic maintenance mode is that when the process production is shut down for maintenance and the process medium is in an empty state, steam backblowing is used for maintenance. The dirty medium generated by backblowing is discharged by controlling the steam backblowing drain valve at the positive pressure end and the steam backblowing drain valve at the negative pressure end on the drain pipe.

Images