Online backwashing method for pipe blockage of u-shaped heat exchanger of chemical production device

Abstract

The application discloses an on-line back-flushing method for U-shaped heat exchanger pipe blockage in chemical production device, which comprises the following steps: adjusting each parameter in the chemical production device, cutting out one U-shaped heat exchanger from the running U-shaped heat exchangers after reaching the requirement; discharging water in the pipe of the cut-out U-shaped heat exchanger, and then intermittently blowing and discharging the water in the pipe by nitrogen; reversely introducing 1.7MPa water from the outlet of the water pump in the device into the outlet of the U-shaped heat exchanger to be flushed, so that the pipeline pressure is sequentially increased to 1.5MPa; the pressure difference between the water in the system and the atmosphere is used as the process driving force to clean and unblock the polymer in the pipe of the U-shaped heat exchanger; the polymer in the pipe of the heat exchanger is discharged from the top of the heat exchanger to the discharge port; the outlet valve of the heat exchanger is slowly closed to sequentially decrease the pipeline pressure to 0MPa, so that one flushing is completed, and the above-mentioned operation is repeated three times; after the back-flushing is completed, the U-shaped heat exchanger after the back-flushing is used. The application has good cleaning and unblocking effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical product preparation, in particular to an online backwashing method for pipe blockage of a U-shaped heat exchanger of a chemical production device. BACKGROUND

[0002] With the extension of the running time period of the chemical production device, some problems are gradually exposed, among which the problem of poor heat exchange effect of the U-shaped heat exchanger is particularly prominent, which directly affects the process control of the extractive distillation column and the long-period operation of the device. The working principle of the U-shaped heat exchanger of the production device is as follows: the medium in the pipe of the U-shaped heat exchanger is water from the extractive distillation column absorption water / extraction water pump 1.7 MPa, 115℃ after system use, the medium in the shell is organic mixture from the packed column liquid pump 0.9 MPa, 23℃, the main function of the U-shaped heat exchanger is to control the temperature of the organic mixture into the extractive distillation column, to adjust the temperature of the extractive distillation column to 66℃, which is beneficial to the temperature adjustment of the middle section of the extractive distillation column and the control of the sensitive plate temperature of the extractive distillation column, to ensure the removal of high-boiling-point substances in the organic mixture in the extractive distillation column, and to facilitate the control of the steam quantity of the extractive distillation column reboiler.

[0003] The U-shaped heat exchanger in the chemical production device is two, and the normal operation is two in series. With the extension of the running period of the device, the heat exchange effect gradually deteriorates, and the operation difficulty of the extractive distillation column and the packed column gradually increases. Through production practice, it is found that the main reason is that with the extension of the running time of the device, the polymer in the system gradually increases, the polymer formed in the system blocks part of the heat exchanger tube bundle, reduces the heat exchange between the pipe and the shell, and reduces the heat exchange efficiency, the temperature of the extractive distillation column gradually decreases, and the outlet pressure gradually decreases, which seriously affects the normal operation of the absorption water and extraction water cooler. Due to the decrease of the front pressure, the absorption water and extraction water quantity decreases, which is difficult to control at the moment, and seriously affects the operation of the device. SUMMARY

[0004] The purpose of the present application is to provide an online backwashing method for pipe blockage of a U-shaped heat exchanger of a chemical production device, which only needs two operators to clear the blockage successfully in one hour, and the water containing uniform particles is discharged from the top of the heat exchanger through the discharge port, which achieves good unblocking effect.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] The online backwashing method for pipe blockage of a U-shaped heat exchanger of a chemical production device comprises the following steps:

[0007] (1) The chemical production device includes two U-shaped heat exchangers, and each parameter in the production device is adjusted, and after the required parameters are reached, one of the running U-shaped heat exchangers is cut out, and the operation of the production device is adjusted in time to ensure the stability of the parameters of the production device;

[0008] (2) The cut-out U-shaped heat exchanger is back-flushed, the water in the pipe of the cut-out U-shaped heat exchanger is discharged, and then nitrogen is intermittently purged to discharge the water in the pipe.

[0009] (3) The water at 1.7 MPa from the outlet of the absorption water / extracted water pump is introduced into the outlet of the cut-out U-shaped heat exchanger in reverse, the pressure in the pipeline is increased to 0.5 MPa, 1.0 MPa and 1.5 MPa in turn, the pressure difference between the water in the system and the atmosphere is used as the process driving force to clear the polymer in the pipe of the U-shaped heat exchanger, and the polymer in the pipe of the heat exchanger is discharged from the top of the heat exchanger to the discharge port, so that the purpose of back-flushing the heat exchanger is achieved.

[0010] (4) Slowly close the outlet valve of the U-shaped heat exchanger to reduce the pressure in the pipeline to 1.0 MPa, 0.5 MPa and 0 MPa in turn, and complete one flushing.

[0011] (5) Steps (3) and (4) are repeated three times, the back-flushing is completed, and the back-flushed U-shaped heat exchanger is put into use, and another U-shaped heat exchanger that has not been back-flushed is cut out online for back-flushing.

[0012] Preferably, in step (1), the chemical production device includes a quenching cooler, a packed absorption tower, a packed absorption tower side cooler, an absorption water heat exchanger, an extracted water heat exchanger, two U-shaped heat exchangers, an extracted rectification tower, an extracted rectification tower layering device, and an absorption water / extracted water buffer tank.

[0013] Preferably, in step (1), the parameters are adjusted as follows: the absorption water flow into the packed absorption tower is reduced from 250 t / h to 230 t / h, the absorption water temperature is increased from 5.5°C to 9.5°C, the temperature after the packed absorption tower side cooler is increased from 6°C to 12°C, the quenching cooler circulating water is closed, the packed absorption tower kettle temperature is increased from 22.5°C to 26.5°C, and the absorption water inlet temperature is increased from 33.5°C to 44°C.

[0014] Preferably, the specific operation of step (2) is as follows: the water in the pipe of the cut-out U-shaped heat exchanger is discharged, and then the nitrogen blowing valve at the bottom of the pipe of the U-shaped heat exchanger is slowly opened to intermittently blow nitrogen to discharge the water in the pipe.

[0015] Preferably, an air vent valve is installed on the pipe of the U-shaped heat exchanger, the air vent valve is connected with an elbow, and the air vent valve is used to discharge the water in the pipe of the cut-out U-shaped heat exchanger.

[0016] Preferably, the pipe passage of the U-shaped water heater is provided with a purging valve, the purging valve is connected with a straight pipe, and the purging valve is used for connecting nitrogen to purge water in the pipe passage of the heat exchanger.

[0017] Preferably, the time interval of the nitrogen purging intermittent purging is 15 minutes.

[0018] Preferably, in the step (3), the specific operation of the reverse introduction is as follows: first, the U-shaped heat exchanger pipe passage vent valve is opened, then the U-shaped heat exchanger pipe passage outlet valve is gradually opened, and the U-shaped heat exchanger cross line valve is closed.

[0019] Preferably, in the step (3), the method that the system water pipeline pressure is sequentially increased to 0.5 MPa, 1.0 MPa and 1.5 MPa is as follows: first, the U-shaped heat exchanger pipe passage vent valve is opened, then the U-shaped heat exchanger pipe passage outlet valve is slowly opened, when the pressure reaches 0.5 MPa, the flow of the U-shaped heat exchanger pipe passage outlet valve is kept unchanged for 2-3 minutes, then the flow of the U-shaped heat exchanger pipe passage outlet valve is continuously increased, when the pressure reaches 1.0 MPa, the flow of the U-shaped heat exchanger pipe passage outlet valve is kept unchanged for 2-3 minutes, then the flow of the U-shaped heat exchanger pipe passage outlet valve is continuously increased, when the pressure reaches 1.5 MPa, the heat exchanger outlet valve is slowly closed after flushing for 10 minutes.

[0020] Preferably, in the step (4), the method that the pipeline pressure is sequentially decreased to 1.0 MPa, 0.5 MPa and 0 MPa by slowly closing the U-shaped heat exchanger outlet valve is as follows: the U-shaped heat exchanger outlet valve is slowly closed, when the pressure reaches 1.0 MPa, the flow of the U-shaped heat exchanger pipe passage outlet valve is kept unchanged for 2-3 minutes, then the heat exchanger outlet valve is closed, when the pressure reaches 0.5 MPa, the flow of the U-shaped heat exchanger pipe passage outlet valve is kept unchanged for 2-3 minutes, then the heat exchanger outlet valve is closed, and when the pressure reaches 0.0 MPa, one operation is completed.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1) By using the method of the present application, only two operators are needed to successfully clear the blockage once in one hour.

[0023] 2) After the block-shaped polymer in the pipe passage of the heat exchanger is dispersed into fine sand, the water containing uniform particles is smoothly discharged from the top of the heat exchanger to the discharge port, and good unblocking effect is achieved.

[0024] 3) The present application only needs to add a vent valve, a purging valve, a bend and a half-meter straight pipe to the U-shaped heat exchanger, the investment cost is only about 500 yuan, the maintenance cost of 300,000 yuan can be saved at one time, 3 tons of 0.3 MPa steam consumption per hour is saved, and the economic benefit is remarkable.

[0025] 4)The present application has the characteristics of energy saving, environmental protection, small investment and high return, and has strong operability. Compared with the methods of air cannon, ammonium sulfate particle online cleaning and the like, the present application has obvious advantages. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural diagram of a chemical production device in an embodiment of the present application;

[0027] Figure 2 is a process diagram of various parameters in the online backwashing method for U-shaped heat exchanger tube blockage of the chemical production device in an embodiment of the present application;

[0028] In the figure, 1 is a quenched tower cooler, 2 is a packed absorption tower, 3 is a packed absorption tower kettle liquid pump, 4 is an absorption water heat exchanger, 5 is an absorption water side line heat exchanger, 6 is a U-shaped heat exchanger, 7 is an extraction water heat exchanger, 8 is an extraction rectification tower layering device, 9 is an absorption water / extraction water buffer tank, 10 is an extraction rectification tower, 11 is a quenched tower cooler condensate cooler, 12 is a packed absorption tower side line pump, and 13 is a quenched tower kettle liquid pump. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] The online backwashing method for U-shaped heat exchanger tube blockage of a chemical production device includes the following steps:

[0031] (1) The chemical production device includes two U-shaped heat exchangers. After adjusting various parameters in the chemical production device, one of the running U-shaped heat exchangers is cut out, and the operation of the chemical production device is adjusted in time to ensure the stability of the parameters of the chemical production device. The parameter adjustment is as follows, as shown in the table. Figure 2 The absorption water flow FC21223 of the packed absorption tower is reduced from 250 t / h to 230 t / h, the absorption water temperature TC21227 of the packed absorption tower side line cooler is increased from 5.5℃ to 9.5℃, the quenched tower cooler condensate cooler post-cooling temperature TC21214 is increased from 6℃ to 12℃, the quenched tower cooler circulating water is closed, the absorption tower kettle temperature TI21226 is increased from 22.5℃ to 26.5℃, and the absorption water inlet temperature TC21228 is increased from 33.5℃ to 44℃.

[0032] (2) The cut-out U-shaped heat exchanger is back-flushed, a vent valve is installed on the tube side of the U-shaped heat exchanger, the vent valve is connected with a bend, the vent valve is used for draining water, before back-flushing, the water in the tube side of the cut-out U-shaped heat exchanger is completely drained, the vent valve of the tube side of the U-shaped heat exchanger is opened first, then the nitrogen blowing valve at the bottom of the tube side of the U-shaped heat exchanger is slowly opened, the nitrogen blowing is intermittent blowing, the water in the tube side is completely drained, the nitrogen blowing valve is used for controlling the flow of nitrogen. The vent valve is installed on the tube side of the U-shaped heat exchanger, the vent valve is connected with a straight pipe, the vent valve is used for connecting the nitrogen blowing to drain the water in the tube side of the heat exchanger, the time interval of the intermittent blowing of the nitrogen blowing is 15 minutes.

[0033] (3) The water at the pump outlet of 1.7 MPa is introduced into the outlet of the cut-out U-shaped heat exchanger to be flushed in reverse, so that the system water pipeline pressure is sequentially increased to 0.5 MPa, 1.0 MPa and 1.5 MPa, the pressure difference between the water in the system and the atmosphere is used as the process driving force to clear the polymer in the tube side of the U-shaped heat exchanger, the polymer in the tube side of the heat exchanger is discharged from the top of the heat exchanger to the discharge port, so as to achieve the purpose of back-flushing the heat exchanger; wherein the specific operation of the reverse introduction is as follows, the vent valve of the tube side of the U-shaped heat exchanger is opened first, then the outlet valve of the tube side of the U-shaped heat exchanger is gradually opened, and the cross-line valve of the cut-out U-shaped heat exchanger is closed; the water pressure in the U-shaped heat exchanger is sequentially increased to 0.5 MPa, 1.0 MPa and 1.5 MPa as follows, the vent valve of the tube side of the U-shaped heat exchanger is opened first, then the outlet valve of the tube side of the U-shaped heat exchanger is slowly opened, when the pressure reaches 0.5 MPa, the flow of the outlet valve of the tube side of the U-shaped heat exchanger is kept unchanged for 2-3 minutes, then the flow of the outlet valve of the U-shaped heat exchanger is continuously increased, when the pressure reaches 1.0 MPa, the flow of the outlet valve of the tube side of the U-shaped heat exchanger is kept unchanged for 2-3 minutes, then the flow of the outlet valve of the U-shaped heat exchanger is continuously increased, when the pressure reaches 1.5 MPa, the flow is stopped.

[0034] (4) Slowly close the outlet valve of the U-shaped heat exchanger to sequentially reduce the pipeline pressure to 1.0 MPa, 0.5 MPa and 0 MPa, and complete the flushing once; wherein the method of slowly closing the outlet valve of the U-shaped heat exchanger to sequentially reduce the pipeline pressure to 1.0 MPa, 0.5 MPa and 0 MPa is as follows, the outlet valve of the U-shaped heat exchanger is slowly closed, when the pressure reaches 1.0 MPa, the flow of the outlet valve of the tube side of the U-shaped heat exchanger is kept unchanged for 2-3 minutes, then the outlet valve of the heat exchanger is closed, when the pressure reaches 0.5 MPa, the flow of the outlet valve of the tube side of the U-shaped heat exchanger is kept unchanged for 2-3 minutes, then the outlet valve of the heat exchanger is closed, until the pressure reaches 0.0 MPa, one operation is completed.

[0035] (5) The steps (3) and (4) are repeatedly operated three times, the back-flushing is completed, the back-flushed U-shaped heat exchanger is put into use, and another U-shaped heat exchanger which is not back-flushed is cut out and back-flushed.

[0036] As Figure 1 shown, the chemical production device includes 1, a quench tower after condenser condensate cooler, 2, a packed absorption tower, 3, a packed absorption tower kettle liquid pump, 4, an absorption water heat exchanger, 5, a packed absorption tower side cooler, 6, a U-shaped heat exchanger, 7, an extraction water heat exchanger, 8, an absorption water / extraction water buffer tank, 9, an absorption water / extraction water pump, 10, an extraction rectification tower, 11, a quenching after condenser condensate cooler, 12, a packed absorption tower side line pump, 13, a quenching after cooler pump. The quenching after cooler 1 is connected with the packed absorption tower 2, and the quenching after cooler 1 and the packed absorption tower 2 are provided with the quenching after cooler pump 13 and the quenching tower after condenser condensate cooler 11. The packed absorption tower 2 is connected with the packed absorption tower side cooler 5 through the packed absorption tower side line circulating pump 12, and the packed absorption tower side cooler 5 is connected with the packed absorption tower 2. Two U-shaped heat exchangers 6 are connected in series, the U-shaped heat exchanger 6 is connected with the packed absorption tower 2 through the packed absorption tower kettle liquid pump 3, and the U-shaped heat exchanger 6 is also connected with the extraction rectification tower 10. The U-shaped heat exchanger 6 is connected with the absorption water heat exchanger 4 and the extraction water heat exchanger 7 respectively, the absorption water heat exchanger 4 is connected with the packed absorption tower 2, and the extraction water heat exchanger 7 is connected with the extraction rectification tower 10. The extraction rectification tower 10 is connected with the absorption water / extraction water buffer tank 8. The packed absorption tower 2, the absorption water / extraction water buffer tank 8, the absorption water / extraction water pump 9 and the U-shaped heat exchanger 6 are connected in sequence.

[0037] The online flushing only needs to be provided with a vent valve and a venting valve, a bend and a half-meter straight pipe.

[0038] By using the method, two operators can successfully clear the blockage once in one hour, one of the operators is responsible for opening and closing the U-shaped heat exchanger outlet valve, and the other operator is responsible for closing the small U-shaped heat exchanger cross line.

[0039] After the block-shaped polymer in the heat exchanger tube is dispersed into fine sand, the water containing uniform particles is discharged from the top of the heat exchanger to the drain discharge port, and good unblocking effect is obtained.

[0040] The above content is only an example and description of the structure of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as the modifications or supplements do not deviate from the structure of the present application or exceed the scope defined by the present application, which shall belong to the protection scope of the present application.

Claims

1. An on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant, characterized in that, The method comprises the following steps: (1) The chemical production device comprises two U-shaped heat exchangers, the parameters in the chemical production device are adjusted, after the requirements are met, one of the running U-shaped heat exchangers is cut out, and the operation of the chemical production device is adjusted in time to ensure that the parameters of the chemical production device are stable. Wherein, a vent valve is arranged on the tube side of the U-shaped heat exchanger, the vent valve is connected with the elbow, a purge valve is arranged on the tube side of the U-shaped heat exchanger, and the purge valve is connected with the straight pipe. The chemical production device comprises a quenching after-cooler condenser, a packed absorption tower, an absorption tower side cooler, an absorption water heat exchanger, an extraction water heat exchanger, two U-shaped heat exchangers, an extraction rectification tower and an absorption water / extraction water buffer tank. The parameters are adjusted as follows: the absorption water flow into the packed absorption tower is reduced from 250 t / h to 230 t / h, the absorption water temperature is increased from 5.5 DEG C to 9.5 DEG C, the temperature of the absorption water cooled by the packed absorption tower side cooler is increased from 6 DEG C to 12 DEG C, the circulation water of the quenching after-cooler is reduced, the packed absorption tower kettle temperature is increased from 22.5 DEG C to 26.5 DEG C, and the absorption water inlet temperature is increased from 33.5 DEG C to 44 DEG C. (2) The cut-out U-shaped heat exchanger is back-flushed, the water in the tube side of the cut-out U-shaped heat exchanger is purged, and then the nitrogen is intermittently purged to discharge the water in the tube side. (3) The water with an outlet pressure of 1.7 MPa of a water pump in the device is reversely introduced from the outlet of the cut-out U-shaped heat exchanger, the pipeline pressure is sequentially increased to 0.5 MPa, 1.0 MPa and 1.5 MPa, the pressure difference between the water in the system and the atmosphere is used as a process driving force to clear the polymer in the tube side of the U-shaped heat exchanger, the polymer in the tube side of the heat exchanger is discharged from the top of the heat exchanger, and thus the purpose of back-flushing the heat exchanger is achieved. Wherein, the specific operation of the reverse introduction is as follows: the vent valve of the tube side of the U-shaped heat exchanger is opened, and then the outlet valve of the tube side of the U-shaped heat exchanger is gradually opened, and at the same time, the cross-line valve of the cut-out U-shaped heat exchanger is closed. (4) The outlet valve of the U-shaped heat exchanger is slowly closed, the pipeline pressure is sequentially reduced to 1.0 MPa, 0.5 MPa and 0 MPa, and one flushing is completed. (5) The steps (3) and (4) are repeatedly operated three times, the back-flushing of the U-shaped heat exchanger is completed, the back-flushed U-shaped heat exchanger is put into use, and another U-shaped heat exchanger which is not back-flushed is cut out on line to be back-flushed.

2. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 1, characterized in that: The specific operation of the step (2) is as follows: the water in the tube side of the cut-out U-shaped heat exchanger is purged, the nitrogen blowing valve at the bottom of the tube side of the U-shaped heat exchanger is slowly opened, and then the water in the tube side is intermittently purged.

3. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 1, characterized in that: The vent valve is used to purge the water in the tube side of the cut-out U-shaped heat exchanger.

4. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 1, characterized in that: The purge valve is used to connect the nitrogen blowing valve to purge the water in the tube side of the heat exchanger.

5. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 2, characterized in that: The time interval of the intermittent nitrogen blowing is 15 minutes.

6. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 1, characterized in that: The pipeline pressure is sequentially raised to 0.5 MPa, 1.0 MPa and 1.5 MPa in the step (3) as follows: first, the U-shaped heat exchanger pipe line vent valve is opened, then the U-shaped heat exchanger pipe line outlet valve is slowly opened, when the pressure reaches 0.5 MPa, the U-shaped heat exchanger pipe line outlet valve flow is kept unchanged, after flushing for 2-3 minutes, the U-shaped heat exchanger pipe line outlet valve is further opened to increase the flow, when the pressure reaches 1.0 MPa, the U-shaped heat exchanger pipe line outlet valve flow is kept unchanged, after flushing for 2-3 minutes, the U-shaped heat exchanger pipe line outlet valve is further opened to increase the flow, when the pressure reaches 1.5 MPa, after flushing for 10 minutes, the heat exchanger outlet valve is slowly closed.

7. The on-line back-flushing method for U-tube heat exchanger tube side plugging in chemical production plant according to claim 1, characterized in that: The pipeline pressure is sequentially lowered to 1.0 MPa, 0.5 MPa and 0 MPa in the step (4) as follows: the U-shaped heat exchanger outlet valve is slowly closed, when the pressure reaches 1.0 MPa, the U-shaped heat exchanger pipe line outlet valve flow is kept unchanged, after flushing for 2-3 minutes, the U-shaped heat exchanger pipe line outlet valve is further closed, when the pressure reaches 0.5 MPa, the U-shaped heat exchanger pipe line outlet valve flow is kept unchanged, after flushing for 2-3 minutes, the U-shaped heat exchanger pipe line outlet valve is further closed, until the pressure reaches 0.0 MPa, one operation is completed.

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