阅读说明：本技术 一种冷却器自动清扫装置及其清扫控制方法 (Automatic cleaning device for cooler and cleaning control method thereof ) 是由 王增乐 曹发栋 王励文 庞晓捷 于 2020-12-01 设计创作，主要内容包括：本发明属于化工生产设备技术领域,具体为一种冷却器自动清扫装置及其清扫控制方法。其应用于负压蒸氨设备中,用于对不凝气冷却器进行自动清扫,不凝气冷却器采用列管式换热器,列管式换热器的壳程与氨气管道连通,列管式换热器的管程与冷却水连通；该装置包括：至少一个增加的列管式换热器、至少四个换热器管程用电磁阀、至少两个换热器壳程用电磁阀、至少四个压力传感器、至少四个温度传感器,以及PLC控制器。该装置可以有效解决负压蒸氨设备中不凝气冷却器的堵塞问题,并进行不停机地自动清扫,清扫效率高,可以有效提高负压蒸氨工艺的效率。(The invention belongs to the technical field of chemical production equipment, and particularly relates to an automatic cleaning device for a cooler and a cleaning control method thereof. The device is applied to negative-pressure ammonia distillation equipment and is used for automatically cleaning a non-condensable gas cooler, the non-condensable gas cooler adopts a tube type heat exchanger, the shell pass of the tube type heat exchanger is communicated with an ammonia gas pipeline, and the tube pass of the tube type heat exchanger is communicated with cooling water; the device includes: the device comprises at least one added tube type heat exchanger, at least four electromagnetic valves for a tube pass of the heat exchanger, at least two electromagnetic valves for a shell pass of the heat exchanger, at least four pressure sensors, at least four temperature sensors and a PLC (programmable logic controller). The device can effectively solve the problem of blockage of the noncondensable gas cooler in the negative-pressure ammonia distillation equipment, automatically cleans without stopping, has high cleaning efficiency, and can effectively improve the efficiency of the negative-pressure ammonia distillation process.)

1. An automatic cleaning device for a cooler is applied to negative pressure ammonia distillation equipment and used for automatically cleaning a non-condensable gas cooler in the negative pressure ammonia distillation equipment, wherein the non-condensable gas cooler adopts a first heat exchanger which is a tubular heat exchanger, the non-condensable gas to be cooled circulates along the shell pass of the first heat exchanger, and a cold fluid for cooling circulates along the tube pass of the first heat exchanger; characterized in that, the automatic cleaning device of cooler includes:

at least one second heat exchanger in parallel with the first heat exchanger; condensed condensate formed by non-condensable gas impurities in shell passes of the first heat exchanger and the second heat exchanger is heated and melted by hot fluid, the hot fluid is generated by a steam boiler, and the hot fluid is transmitted through a steam pipeline;

at least four electromagnetic valves for tube pass, which are respectively used for controlling the tube pass of the first heat exchanger or the second heat exchanger to/from the hot fluid in the steam pipeline or the cold fluid in the condensation pipeline;

at least two shell pass electromagnetic valves which are respectively used for controlling the non-condensable gas fluid in the ammonia pipeline to enter/exit the shell pass of the first heat exchanger or the second heat exchanger;

the four pressure sensors are respectively used for detecting the pressure of the front end and the rear end of the shell pass of the first heat exchanger and the pressure of the front end and the rear end of the shell pass of the second heat exchanger;

the four temperature sensors are respectively used for detecting the fluid temperature of the front end and the rear end of the first heat exchanger tube pass and the fluid temperature of the front end and the rear end of the second heat exchanger tube pass; and

the PLC is used for receiving and analyzing the detection results of the pressure sensor and the temperature sensor; judging the conduction degree of the shell pass of the first heat exchanger or the second heat exchanger according to the detection result, and controlling the opening and closing states of the electromagnetic valve for the tube pass and the electromagnetic valve for the shell pass according to the conduction degree of the shell pass of the first heat exchanger or the second heat exchanger; the steam boiler, the shell pass electromagnetic valve, the tube pass electromagnetic valve, the temperature sensor and the pressure sensor are all electrically connected with the PLC;

the judgment and control process of the PLC controller is as follows:

when one of the first heat exchanger and the second heat exchanger is in an operating state, detecting the air pressure difference delta p at two ends of a shell pass and the temperature difference delta t at two ends of a tube pass of the heat exchanger:

(1) when at least one condition of P0 is less than or equal to Δ P or T0 is met, judging that the shell side of the heat exchanger is not blocked; at the moment, the normal working state of the heat exchanger is kept;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met and the state is continuously kept for a specific time period T, judging that the shell side of the heat exchanger A is obviously blocked; at the moment, the non-condensable gas in the ammonia gas pipeline and the cold fluid in the condensation pipeline are switched into another heat exchanger for cooling, the cold fluid in the tube pass of the heat exchanger is switched into the hot fluid in the steam pipeline, and the shell pass of the heat exchanger is heated and cleaned;

the T0 and the P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

when one of the first heat exchanger and the second heat exchanger is in a cleaning state, detecting air pressures p1 and p2 at two ends of a shell side of the heat exchanger; and temperatures t1, t2 at both ends of the tube side:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process;

wherein, P1 and T1 are both specific values determined by experts in the field according to experience; the conditions for this value determination are: after cleaning is finished, the fluid pressure at the two ends of the shell pass and the fluid temperature at the two ends of the tube pass are in a very close state, but a certain difference exists in numerical value; and determining that the maximum difference value between the values of the shell pass and the tube pass is P1 and T1 when the cleaning knot is in a finished state, and considering that the cleaning process is not finished when the actual measurement value is larger than the specific value and considering that the cleaning process is finished when the actual measurement value is not larger than the specific value.

2. The automatic cleaning device for a cooler according to claim 1, wherein: the electromagnetic valves for the tube side are two-position three-way electromagnetic valves and respectively comprise a first electromagnetic valve, a second electromagnetic valve, a third electromagnetic valve and a fourth electromagnetic valve; the first electromagnetic valve and the third electromagnetic valve are both two-inlet one-outlet electromagnetic valves, one inlet of the first electromagnetic valve and one inlet of the third electromagnetic valve are communicated with the input port of the steam pipeline, the other inlet of the first electromagnetic valve and the third electromagnetic valve are communicated with the input port of the condensation pipeline, and outlets of the first electromagnetic valve and the third electromagnetic valve are communicated with the tube pass inlet of the first heat exchanger; the second electromagnetic valve and the fourth electromagnetic valve are both one-inlet two-outlet electromagnetic valves, and inlets of the second electromagnetic valve and the fourth electromagnetic valve are communicated with a tube pass outlet of the second heat exchanger; one outlet of the second electromagnetic valve and the fourth electromagnetic valve is communicated with the steam recovery pipeline, and the other outlet of the second electromagnetic valve and the fourth electromagnetic valve is communicated with the condensed water recovery pipeline.

3. The automatic cleaning device for a cooler according to claim 1, wherein: the shell-side electromagnetic valves are two-position three-way electromagnetic valves which are respectively a fifth electromagnetic valve and a sixth electromagnetic valve, the fifth electromagnetic valve is a one-inlet two-outlet electromagnetic valve, an inlet of the fifth electromagnetic valve is communicated with an inlet of the ammonia gas pipeline, one outlet of the first electromagnetic valve C is communicated with a shell-side inlet of the first heat exchanger, and the other outlet of the first electromagnetic valve C is communicated with a shell-side inlet of the second heat exchanger; the sixth electromagnetic valve is a two-inlet one-outlet electromagnetic valve, one inlet of the sixth electromagnetic valve is communicated with the shell pass outlet of the first heat exchanger, and the other inlet of the sixth electromagnetic valve is communicated with the shell pass outlet of the second heat exchanger; and the outlet of the sixth electromagnetic valve is communicated with an ammonia water return pipeline.

4. The automatic cleaning device for a cooler according to claim 1, wherein: the pressure sensors comprise a first pressure sensor, a second pressure sensor, a third pressure sensor and a fourth pressure sensor; spherical pressure detection chambers are respectively arranged at the shell pass inlet and the shell pass outlet of the first heat exchanger and the second heat exchanger; the first pressure sensor is positioned at the front end of the shell pass of the first heat exchanger, and the second pressure sensor is positioned at the rear end of the shell pass of the first heat exchanger; the third pressure sensor is positioned at the front end of the shell pass of the second heat exchanger, and the fourth pressure sensor is positioned at the rear end of the shell pass of the second heat exchanger; the pressure sensor is a corrosion-resistant high-temperature gas pressure sensor, a sensing element of the pressure sensor is positioned in the pressure detection cavity, and a conversion element of the pressure sensor is positioned outside the pressure detection cavity.

5. The automatic cleaning device for a cooler according to claim 1, wherein: the temperature sensors comprise a first temperature sensor, a second temperature sensor, a third temperature sensor and a fourth temperature sensor; fluid temperature detection chambers are respectively arranged at the tube pass inlets and the tube pass outlets of the first heat exchanger and the second heat exchanger; the first temperature sensor is positioned at the front end of the tube pass of the first heat exchanger, and the second temperature sensor is positioned at the rear end of the tube pass of the first heat exchanger; the third temperature sensor is positioned at the front end of the tube pass of the second heat exchanger, and the fourth temperature sensor is positioned at the rear end of the tube pass of the second heat exchanger.

6. The automatic cleaning device for a cooler according to claim 1, wherein: the hot fluid in the steam pipeline is high-temperature steam, and the cold fluid in the condensation pipeline is cooling water; the steam recovery pipeline and the condensate water recovery pipeline are both communicated with the circulating water recovery tank; cooling water in the circulating water recovery tank flows back through the reflux pump to be used as a water source for producing steam or cooling water; the reflux pump is electrically connected with the PLC controller, and the running state of the reflux pump is controlled by the PLC controller.

7. The automatic cooler sweeping device according to claim 6, wherein: the steam boiler is communicated with the steam pipeline through a single-pass electromagnetic valve, and the single-pass electromagnetic valve controls fluid to flow into the steam pipeline along the steam boiler; the steam boiler and the single-way electromagnetic valve are electrically connected with the PLC, and the running state of the steam boiler and the single-way electromagnetic valve is controlled by the PLC.

8. The automatic cleaning device for a cooler according to claim 1, wherein: the first heat exchanger and the second heat exchanger are both tube type heat exchangers; the first heat exchanger and the second heat exchanger are used in a time-sharing mode, when one heat exchanger is used for cooling fluid in the ammonia gas pipeline, the other heat exchanger is in a shell side cleaning state or an idle state.

9. A cleaning control method is characterized in that: the method is applied to the automatic cooler cleaning device of any one of claims 1-8, and is controlled by a PLC (programmable logic controller) in the automatic cooler cleaning device, and comprises the following processes:

s1, cooling the non-condensable gas by the first heat exchanger in an initial state; the PLC controls fluid in the ammonia gas pipeline to enter and exit along the shell pass of the first heat exchanger through a fifth electromagnetic valve and a sixth electromagnetic valve; the PLC controls cold fluid in the condensation pipeline to enter and exit along the tube pass of the first heat exchanger through the first electromagnetic valve and the second electromagnetic valve, the single-way electromagnetic valve is closed, and the shell pass and the tube pass of the second heat exchanger are both in an idle state; keeping the state to operate;

s2, in the operating state of the previous step, the PLC detects the pressure in the pressure detection cavities at the two ends of the shell pass of the first heat exchanger through the first pressure sensor and the second pressure sensor and calculates the air pressure difference delta p, and the PLC detects the cold fluid temperature in the fluid temperature detection cavities at the two ends of the tube pass of the first heat exchanger through the first temperature sensor and the second temperature sensor and calculates the temperature difference delta t;

s3, the PLC makes the following judgment and decision according to the detection result of the air pressure difference delta p and the temperature difference delta t:

(1) when at least one condition of P0 being less than or equal to Δ P or T0 being more than or equal to Δ T is met, judging that the shell side of the heat exchanger A is not blocked; at the moment, the normal working state of the first heat exchanger is kept;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met, judging that the shell side of the heat exchanger A is obviously blocked; at this time, the following sweeping strategy is implemented: the fluid in the ammonia pipeline is switched to enter and exit along the shell side of the second heat exchanger under the control of a fifth electromagnetic valve and a sixth electromagnetic valve; the steam boiler works, and the single-way electromagnetic valve is conducted; meanwhile, through the control of the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve, hot fluid in the steam pipeline enters and exits along the tube pass of the first heat exchanger, and cold fluid in the condensation pipeline enters and exits along the tube pass of the second heat exchanger;

the T0 and the P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

s4, when the first heat exchanger is in a cleaning state, the fluid temperatures t1 and t2 at two ends of the tube side of the first heat exchanger are continuously detected through the first temperature sensor and the second temperature sensor, the pressures p1 and p2 at two ends of the shell side of the first heat exchanger are continuously monitored through the first pressure sensor and the second pressure sensor, and the following judgment and decision are made according to the detection result:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process;

wherein, P1 and T1 are specific values empirically determined by experts in the field; the conditions for this value determination are: after cleaning is finished, the fluid pressure at the two ends of the shell pass and the fluid temperature at the two ends of the tube pass are in a very close state, but a certain difference exists in numerical value; determining the maximum difference value of the values at the two ends of the shell pass and the tube pass as P1 and T1 under the cleaning knot completion state, considering that the cleaning process is not completed when the actual measurement value is greater than the specific value, and considering that the cleaning process is completed when the actual measurement value is not greater than the specific value;

and S5, when the second heat exchanger is in a cooling working state, performing detection, judgment and decision processes of the steps S2 and S3 on the second heat exchanger, when the situation that the shell side of the second heat exchanger is in a blocked state is detected, switching the non-condensable gas fluid in the ammonia gas pipeline into the shell side of the first heat exchanger after cleaning is completed, and simultaneously performing a cleaning process of the step S4 on the second heat exchanger.

Technical Field

The invention belongs to the technical field of chemical production equipment, and particularly relates to an automatic cleaning device for a cooler and a cleaning control method thereof.

Background

The ammonia-containing wastewater is waste generated in the production process of a chemical plant, the problem of treating the ammonia-containing wastewater is a common problem in the chemical industry, and related ammonia distillation processes and equipment are required to be used for carrying out harmless treatment on the ammonia-containing wastewater in almost all oil refineries, alkali-associated plants, fertilizer plants and coking plants at present.

At present, a part of chemical enterprises adopt a negative-pressure ammonia distillation process to treat ammonia-containing wastewater, in the process, a tubular furnace is used for heating and decompressing the ammonia distillation wastewater, so that the ammonia distillation wastewater at a certain temperature reaches a supersaturated state to precipitate steam, gas-liquid separation is completed in an evaporator, the steam enters an ammonia distillation tower to distill ammonia, and separated water enters a wastewater intermediate tank and is pumped into the tubular furnace for reheating. And (3) evaporating ammonia from the rich ammonia water in an ammonia still to generate ammonia steam and ammonia evaporation wastewater, and cooling the ammonia evaporation wastewater and then sending the ammonia evaporation wastewater to a phenol-cyanogen sewage treatment station for treatment. The main components of the ammonia vapor are ammonia and water vapor, after the components are cooled by an ammonia dephlegmator at the tower top, part of condensate liquid flows back to an ammonia still, the uncondensed ammonia vapor enters a full condenser to be cooled, and the condensate liquid generated by cooling is mainly ammonia water with the concentration of 17%. The ammonia water flows into the ammonia water reflux tank automatically and is pumped to the ammonia still for reflux or used in the downstream process.

In the negative pressure ammonia distillation process, liquid ammonia water is arranged at the lower part of the ammonia water reflux tank, various uncondensed gases are arranged in the upper space of the ammonia water reflux tank, and the uncondensed gases are called non-condensable gases. The non-condensable gas enters the non-condensable gas cooler, the non-condensable gas cooler further cools the non-condensable gas, so that part of gas in the non-condensable gas is liquefied and flows into the ammonia water reflux tank automatically, and the residual non-condensable gas components enter the vacuum injection device. The vacuum jet device is mainly composed of a pump, a jet ejector, a circulating water tank and a control part, and generates negative pressure on a non-condensable gas cooler, a full condenser, an ammonia water fractional condenser, an ammonia still and an evaporator. The vacuum injection device sends the sucked non-condensable gas and the sucked circulating liquid into a circulating water tank for gas-liquid separation, the gas is sent to a coal gas negative pressure system for recovery, and the liquid serving as the circulating liquid is continuously pumped to the water tank of the vacuum device for use.

The prior negative pressure ammonia distillation process equipment also has the following defects: the non-condensable gas cooler usually uses a stainless steel tube type heat exchanger, which is cooled by low-temperature water, the low-temperature water goes through a tube side, and the non-condensable gas component goes through a shell side. In actual operation, part of hydrocarbon impurities and other organic impurities in the non-condensable gas component can be condensed to generate a soft solid mixture with a low melting point, and the soft solid impurities can be attached to the outside of a tube array of the cooler to block a shell side channel of the heat exchanger. When the blockage problem is serious, the condensation effect of the cooler is deteriorated, the circulation resistance of the fluid is increased, the vacuum degree of the equipment is reduced, and the negative pressure ammonia distillation process cannot be normally carried out.

The conventional method for solving the problem of heat exchanger blockage is to purge a shell pass channel of the heat exchanger through high-temperature steam, and the negative-pressure ammonia distillation equipment needs to be integrally stopped in the purging process; the traditional blowing mode is characterized in that steam is introduced into the shell side to heat and melt blocked substances, the contact area of hot steam and the blocking substances is small, the heat conduction effect is poor, the heating time is long, and the blowing efficiency is low. In addition, the traditional purging mode can also generate more ammonia-containing wastewater, and the operating pressure of the negative-pressure ammonia distillation system is increased.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide an automatic cleaning device for a cooler and a cleaning control method thereof, which can effectively solve the problem of blockage of a noncondensable gas cooler in negative-pressure ammonia distillation equipment, can automatically clean the noncondensable gas cooler without stopping the machine, has high cleaning efficiency and can effectively improve the efficiency of a negative-pressure ammonia distillation process.

In order to achieve the purpose, the invention provides the following technical scheme:

an automatic cleaning device of a cooler is applied to negative pressure ammonia distillation equipment and used for automatically cleaning a non-condensable gas cooler in the negative pressure ammonia distillation equipment, wherein the non-condensable gas cooler adopts a first heat exchanger which is a tubular heat exchanger, non-condensable gas to be cooled circulates along the shell pass of the first heat exchanger, and fluid for cooling circulates along the tube pass of the first heat exchanger; the automatic cleaning device of cooler includes: the heat exchanger comprises at least one second heat exchanger, at least four electromagnetic valves for tube side, at least two electromagnetic valves for shell side, at least four pressure sensors, at least four temperature sensors and a PLC (programmable logic controller).

The second heat exchanger is connected with the first heat exchanger in parallel; the steam boiler is used for providing hot fluid, the hot fluid is transmitted through a steam pipeline, and the hot fluid is used for heating condensed condensate formed by non-condensable gas impurities in the shell pass of the first heat exchanger or the second heat exchanger.

The four tube pass electromagnetic valves are respectively used for controlling hot fluid in the steam pipeline or cold fluid in the condensation pipeline to respectively enter/exit the tube passes of the first heat exchanger or the second heat exchanger. And the two shell pass electromagnetic valves are respectively used for controlling the non-condensable gas fluid in the ammonia gas pipeline to respectively enter/exit the shell passes of the first heat exchanger or the second heat exchanger.

The four pressure sensors are respectively used for detecting the air pressure at the front end and the rear end of the shell pass of the first heat exchanger and detecting the air pressure at the front end and the rear end of the shell pass of the second heat exchanger; the at least four temperature sensors are respectively used for detecting the fluid temperature of the front end and the rear end of the first heat exchanger tube pass and the fluid temperature of the front end and the rear end of the second heat exchanger tube pass.

The PLC is used for receiving and analyzing the detection results of the pressure sensor and the temperature sensor; judging the conduction degree of the shell pass of the first heat exchanger or the second heat exchanger according to the detection result, and controlling the opening and closing states of the electromagnetic valve for the tube pass and the electromagnetic valve for the shell pass according to the conduction degree of the shell pass of the first heat exchanger or the second heat exchanger; the steam boiler, the shell side electromagnetic valve, the tube side electromagnetic valve, the temperature sensor and the pressure sensor are all electrically connected with the PLC.

The judgment and control process of the PLC controller is as follows:

when one of the first heat exchanger and the second heat exchanger is in an operating state, detecting a pressure difference delta p at two ends of a shell pass of the heat exchanger and a temperature difference delta t at two ends of a tube pass:

(1) when at least one condition of P0 is less than or equal to Δ P or T0 is met, judging that the shell side of the heat exchanger is not blocked; at the moment, the normal working state of the heat exchanger is kept;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met and the state is continuously maintained for a specific time period T, judging that the shell side of the heat exchanger A is obviously blocked; at the moment, the non-condensable gas in the ammonia gas pipeline and the cold fluid in the condensation pipeline are switched into another heat exchanger for cooling, the cold fluid in the tube pass of the heat exchanger is switched into the hot fluid in the steam pipeline, and the shell pass of the heat exchanger is heated and cleaned;

wherein, T0 and P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

when one of the first heat exchanger and the second heat exchanger is in a cleaning state, detecting air pressures p1 and p2 at two ends of a shell side of the heat exchanger; and temperatures t1, t2 at both ends of the tube side:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process;

wherein P1 and T1 are specific values empirically determined by an expert in the field; the conditions for this value determination are: after cleaning is finished, the air pressure at the two ends of the shell pass and the temperature of the tube pass are in a state close to each other, and the values have certain difference, the maximum difference value of the values at the two ends after cleaning is determined to be P1 and T1, when the actual measurement value is larger than the specific value, the cleaning process is considered to be not finished, and when the actual measurement value is not larger than the specific value, the cleaning process is considered to be finished.

Furthermore, the electromagnetic valves for the tube side are two-position three-way electromagnetic valves which respectively comprise a first electromagnetic valve, a second electromagnetic valve, a third electromagnetic valve and a fourth electromagnetic valve; the first electromagnetic valve and the third electromagnetic valve are both two-inlet one-outlet electromagnetic valves, one inlet of the first electromagnetic valve and one inlet of the third electromagnetic valve are communicated with the input port of the steam pipeline, the other inlet of the first electromagnetic valve and the third electromagnetic valve are communicated with the input port of the condensation pipeline, and outlets of the first electromagnetic valve and the third electromagnetic valve are communicated with the tube pass inlet of the first heat exchanger; the second electromagnetic valve and the fourth electromagnetic valve are both one-inlet two-outlet electromagnetic valves, and inlets of the second electromagnetic valve and the fourth electromagnetic valve are communicated with a tube pass outlet of the second heat exchanger; one outlet of the second electromagnetic valve and the fourth electromagnetic valve is communicated with the steam recovery pipeline, and the other outlet of the second electromagnetic valve and the fourth electromagnetic valve is communicated with the condensed water recovery pipeline.

Furthermore, the shell-side electromagnetic valves are two-position three-way electromagnetic valves which are respectively a fifth electromagnetic valve and a sixth electromagnetic valve, the fifth electromagnetic valve is a one-inlet two-outlet electromagnetic valve, an inlet of the fifth electromagnetic valve is communicated with an inlet of the ammonia gas pipeline, one outlet of the first electromagnetic valve C is communicated with the shell-side inlet of the first heat exchanger, and the other outlet of the first electromagnetic valve C is communicated with the shell-side inlet of the second heat exchanger; the sixth electromagnetic valve is a two-inlet one-outlet electromagnetic valve, one inlet of the sixth electromagnetic valve is communicated with the shell pass outlet of the first heat exchanger, and the other inlet of the sixth electromagnetic valve is communicated with the shell pass outlet of the second heat exchanger; and the outlet of the sixth electromagnetic valve is communicated with an ammonia water return pipeline.

Further, the pressure sensors include a first pressure sensor, a second pressure sensor, a third pressure sensor, and a fourth pressure sensor; spherical pressure detection chambers are respectively arranged at the shell pass inlet and the shell pass outlet of the first heat exchanger and the second heat exchanger; the first pressure sensor is positioned at the front end of the shell pass of the first heat exchanger, and the second pressure sensor is positioned at the rear end of the shell pass of the first heat exchanger; the third pressure sensor is positioned at the front end of the shell pass of the second heat exchanger, and the fourth pressure sensor is positioned at the rear end of the shell pass of the second heat exchanger; the pressure sensor is a corrosion-resistant high-temperature gas pressure sensor, a sensing element of the pressure sensor is positioned in the pressure detection cavity, and a conversion element of the pressure sensor is positioned outside the pressure detection cavity.

Further, the temperature sensors include a first temperature sensor, a second temperature sensor, a third temperature sensor and a fourth temperature sensor; fluid temperature detection chambers are respectively arranged at the tube pass inlets and the tube pass outlets of the first heat exchanger and the second heat exchanger; the first temperature sensor is positioned at the front end of the tube pass of the first heat exchanger, and the second temperature sensor is positioned at the rear end of the tube pass of the first heat exchanger; the third temperature sensor is positioned at the front end of the tube pass of the second heat exchanger, and the fourth temperature sensor is positioned at the rear end of the tube pass of the second heat exchanger.

Furthermore, cold fluid in the condensation pipeline is low-temperature cooling water, and hot fluid in the steam pipeline is high-temperature steam; the steam recovery pipeline and the condensate water recovery pipeline are both communicated with the circulating water recovery tank; cooling water in the circulating water recovery tank flows back through the reflux pump to be used as a water source for producing steam or cooling water; the reflux pump is electrically connected with the PLC controller, and the running state of the reflux pump is controlled by the PLC controller.

Furthermore, the steam boiler is communicated with the steam pipeline through a single-way electromagnetic valve, and the single-way electromagnetic valve controls fluid to flow into the steam pipeline along the steam boiler; the steam boiler and the single-way electromagnetic valve are electrically connected with the PLC, and the running state of the steam boiler and the single-way electromagnetic valve is controlled by the PLC.

Further, the first heat exchanger and the second heat exchanger are both tube type heat exchangers; the first heat exchanger and the second heat exchanger are used in a time-sharing mode, when one heat exchanger is used for cooling fluid in the ammonia gas pipeline, the other heat exchanger is in a shell side cleaning state or an idle state.

The invention also provides a cleaning control method, which is applied to the automatic cleaning device of the cooler and is controlled by a PLC (programmable logic controller) in the automatic cleaning device of the cooler, and the method comprises the following steps:

s1, cooling the non-condensable gas by the first heat exchanger in an initial state; the PLC controls fluid in the ammonia gas pipeline to enter and exit along the shell pass of the first heat exchanger through a fifth electromagnetic valve and a sixth electromagnetic valve; the PLC controls cold fluid in the condensation pipeline to enter and exit along the tube pass of the first heat exchanger through the first electromagnetic valve and the second electromagnetic valve, the steam boiler does not work, the single-pass electromagnetic valve is closed, and the shell pass and the tube pass of the second heat exchanger are both in an idle state; keeping the state to operate;

s2, in the operating state of the previous step, the PLC detects the pressure in the pressure detection cavities at the two ends of the shell pass of the first heat exchanger through the first pressure sensor and the second pressure sensor and calculates the air pressure difference delta p, and the PLC detects the cold fluid temperature in the fluid temperature detection cavities at the two ends of the tube pass of the first heat exchanger through the first temperature sensor and the second temperature sensor and calculates the temperature difference delta t;

s3, the PLC makes the following judgment and decision according to the detection result of the air pressure difference delta p and the temperature difference delta t:

(1) when at least one condition of P0 being less than or equal to Δ P or T0 being more than or equal to Δ T is met, judging that the shell side of the heat exchanger A is not blocked; at the moment, the normal working state of the first heat exchanger is kept;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met, judging that the shell side of the heat exchanger A is obviously blocked; at this time, the following sweeping strategy is implemented:

the fluid in the ammonia pipeline is switched to enter and exit along the shell side of the second heat exchanger under the control of a fifth electromagnetic valve and a sixth electromagnetic valve; the steam boiler works, and the single-way electromagnetic valve is conducted; meanwhile, through the control of the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve, hot fluid in the steam pipeline enters and exits along the tube pass of the first heat exchanger, and cold fluid in the condensation pipeline enters and exits along the tube pass of the second heat exchanger;

wherein, T0 and P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

s4, when the first heat exchanger is in a cleaning state, the fluid temperatures t1 and t2 at two ends of the tube side of the first heat exchanger are continuously detected through the first temperature sensor and the second temperature sensor, the pressures p1 and p2 at two ends of the shell side of the first heat exchanger are continuously monitored through the first pressure sensor and the second pressure sensor, and the following judgment and decision are made according to the detection result:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process;

wherein P1 and T1 are specific values empirically determined by an expert in the field; the conditions for this value determination are: after cleaning is finished, the pressure at two ends of the shell pass and the temperature of the tube pass are in a state of being very close to each other, and certain difference exists in numerical values, the maximum difference value of the numerical values at the two ends after cleaning is determined to be P1 and T1, when the actual measured value is larger than the specific value, the cleaning process is considered to be not finished, and when the actual measured value is not larger than the specific value, the cleaning process is considered to be finished;

and S5, when the second heat exchanger is in a cooling working state, performing detection, judgment and decision processes of the steps S2 and S3 on the second heat exchanger, when the situation that the shell side of the second heat exchanger is in a blocked state is detected, switching the non-condensable gas fluid in the ammonia gas pipeline into the shell side of the first heat exchanger after cleaning is completed, and simultaneously performing a cleaning process of the step S4 on the second heat exchanger.

The automatic cleaning device for the cooler and the cleaning control method thereof provided by the invention have the following beneficial effects:

1. the automatic cleaning device adopts a multi-heat exchanger mode, when one heat exchanger is blocked, the cooling process of non-condensable gas can be automatically switched to other heat exchangers, at least one heat exchanger is guaranteed to be in an operable state, and therefore the process flow of the negative pressure ammonia distillation process is guaranteed not to be interrupted, wherein the actions of detection of the blocked state, cleaning, switching and the like are automatically completed by a PLC (programmable logic controller), manual intervention is not needed, and the automation degree of equipment is extremely high.

2. The device is provided with temperature and pressure sensors which respectively detect the temperature and the pressure of fluid at two ends of a tube side and a shell side of the heat exchanger; when the shell pass of the heat exchanger is blocked or the smoothness is reduced, the pressure intensity of the fluid at the two ends of the shell pass is inevitably increased, and the temperature difference of the fluid for cooling at the two ends of the tube pass is inevitably reduced along with the reduction of the flow rate of the fluid in the shell pass; by combining the two criteria, the blockage state of the shell pass can be found more accurately in advance, and cleaning treatment can be carried out in time.

3. Meanwhile, the smoothness of the pipeline in the cleaning state can be detected by combining the criterion of the temperature and the air pressure, so that the device can cut off the flow of the fluid in the steam pipeline in time after the cleaning state is finished, and the energy consumption of the device in the invalid operation state is reduced.

4. The condensed water that the device cooling process used and the high temperature vapor that uses among the heating process all retrieve at the back end and recycle, can regard as the circulation water source of steam or condensed water, and condensation duct and steam conduit are isolated with the ammonia pipeline that contains organic matter, have reduced the production of sewage, have higher energy-conservation and feature of environmental protection.

5. In the cleaning process of the automatic cleaning device provided by the invention, a condensate in a shell pass is heated in a tube pass heating mode; therefore, compared with the traditional sweeping process, the heating efficiency is higher, and the sweeping effect is better.

6. The invention adopts a plurality of two-position three-way electromagnetic valves to switch the flow direction of the fluid in different pipelines, thereby reducing the use of the valve body and improving the switching efficiency of the flow direction of the fluid; the comprehensive cost of the negative pressure ammonia distillation equipment can be effectively controlled.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a part of a negative pressure ammonia still equipment according to embodiment 1 of the present invention, which includes an automatic cleaning device for a cooler;

FIG. 2 is a schematic structural view of an automatic cleaning apparatus for a cooler in embodiment 1 of the present invention;

fig. 3 is a schematic structural view of a first heat exchanger in embodiment 1 of the present invention;

FIG. 4 is a block diagram showing the automatic cleaning apparatus for a cooler in accordance with embodiment 1 of the present invention;

FIG. 5 is a flowchart showing the operation of the automatic cleaning apparatus for a cooler in embodiment 2 of the present invention

The figure is marked with: 1. a first heat exchanger; 2. a second heat exchanger; 3. a first solenoid valve; 4. a second solenoid valve; 5. a third electromagnetic valve; 6. a fourth solenoid valve; 7. a fifth solenoid valve; 8. a sixth electromagnetic valve; 9. a circulating water recovery tank; 10. a reflux pump; 11. a steam boiler; 12. a one-way solenoid valve; 13. a first temperature sensor; 14. a second temperature sensor; 15. a third temperature sensor; 16. a fourth temperature sensor; 17. a first pressure sensor; 18. a second pressure sensor; 19. a third pressure sensor; 20. a fourth pressure sensor; 21. a first total condenser; 22. a second complete condenser; 23. an ammonia water reflux tank; 24. a vacuum injection device; 25. a vacuum device water tank; 31. a steam line; 32. a condensing duct; 33. an ammonia water reflux pipeline; 34. an ammonia gas pipeline; 35. a condensate recovery pipeline; 36. a vapor recovery conduit; 100. a PLC controller; 101. a tube side inlet; 102. a tube side outlet; 103. a shell-side inlet; 104. a shell-side outlet; 105. a pressure detection chamber; 106. a fluid temperature sensing chamber.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

As shown in fig. 1, the automatic cleaning device for a cooler provided by this embodiment is applied to a negative pressure ammonia still, and is used for automatically cleaning a non-condensable gas cooler in the negative pressure ammonia still, where the non-condensable gas cooler is a first heat exchanger 1, the first heat exchanger 1 is a tube heat exchanger, a shell side of the first heat exchanger 1 is communicated with an ammonia gas pipeline 34, and a tube side of the first heat exchanger 1 is communicated with a condensation pipeline 32; in the negative pressure ammonia distillation equipment, a vacuum injection device 24 is communicated with a vacuum device water tank 25, the vacuum injection device 24 utilizes the high-speed flow of liquid to generate an injection and suction effect to suck the non-condensable gas in an ammonia pipeline 34 into a first heat exchanger 1, and the vacuum injection device 24 generates a negative pressure state for equipment such as the first heat exchanger 1, a second heat exchanger 2, a first full condenser 21, a second full condenser 22, an ammonia water partial condenser, an ammonia distillation tower, an evaporator and the like. Meanwhile, the vacuum injection device 24 sends the sucked non-condensable gas and the sucked circulating liquid into the ammonia water return tank 23 for gas-liquid separation, the gas is sent to a coal gas negative pressure system for recycling, and the liquid serving as the circulating liquid is continuously pumped to the vacuum device water tank 25 for use.

As shown in fig. 2, the present embodiment provides an automatic cleaning device for a cooler, including: at least one second heat exchanger 2, at least four solenoid valves for tube pass, at least two solenoid valves for shell pass, at least four pressure sensors, at least four temperature sensors, and a PLC controller 100.

The second heat exchanger 2 is connected with the first heat exchanger 1 in parallel; the steam boiler 11 is used for providing hot fluid, the hot fluid is transmitted through a steam pipeline 31, and the hot fluid is used for heating condensed condensate formed by non-condensable gas impurities in the shell side of the first heat exchanger 1 or the second heat exchanger 2.

Four tube-side electromagnetic valves are respectively used for controlling the hot fluid in the steam pipeline 31 or the cold fluid in the condensation pipeline 32 to enter/exit the tube side of the first heat exchanger 1 or the second heat exchanger 2. The two shell-side electromagnetic valves are respectively used for controlling the non-condensable gas fluid in the ammonia gas pipeline 34 to respectively enter/exit the shell side of the first heat exchanger 1 or the second heat exchanger 2.

The four pressure sensors are respectively used for detecting the air pressure at the front end and the rear end of the shell pass of the first heat exchanger 1 and detecting the air pressure at the front end and the rear end of the shell pass of the second heat exchanger 2; the at least four temperature sensors are respectively used for detecting the fluid temperature at the front end and the rear end of the tube side of the first heat exchanger 1 and detecting the fluid temperature at the front end and the rear end of the tube side of the second heat exchanger 2.

The PLC 100 is used for receiving and analyzing the detection results of the pressure sensor and the temperature sensor; judging the conduction degree of the shell pass of the first heat exchanger 1 or the second heat exchanger 2 according to the detection result, and controlling the opening and closing states of the electromagnetic valve for the tube pass and the electromagnetic valve for the shell pass according to the conduction degree of the shell pass of the first heat exchanger 1 or the second heat exchanger 2; as shown in fig. 4, the steam boiler 11, the shell-side solenoid valve, the tube-side solenoid valve, the temperature sensor, and the pressure sensor are electrically connected to the PLC controller 100.

The judgment and control process of the PLC controller 100 is as follows:

when one of the first heat exchanger 1 and the second heat exchanger 2 is in an operating state, detecting the air pressure difference delta p at two ends of a shell pass and the temperature difference delta t at two ends of a tube pass of the heat exchanger:

(1) when at least one condition of P0 is less than or equal to Δ P or T0 is met, judging that the shell side of the heat exchanger is not blocked; at the moment, the normal working state of the heat exchanger is kept;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met, judging that the shell side of the heat exchanger A is obviously blocked; at the moment, the non-condensable gas in the ammonia gas pipeline 34 and the cold fluid in the condensation pipeline 32 are switched into another heat exchanger for cooling, the cold fluid in the tube pass of the heat exchanger is switched into the hot fluid in the steam pipeline 31, and the shell pass of the heat exchanger is heated and cleaned;

wherein, T0 and P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

when one of the first heat exchanger 1 and the second heat exchanger 2 is in a cleaning state, detecting the air pressures p1 and p2 at two ends of the shell side of the heat exchanger; and temperatures t1, t2 at both ends of the tube side:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process;

wherein P1 and T1 are specific values empirically determined by an expert in the field; the conditions for this value determination are: after cleaning is finished, the air pressure at the two ends of the shell pass and the temperature of the tube pass are in a state close to each other, and the values have certain difference, the maximum difference value of the values at the two ends after cleaning is determined to be P1 and T1, when the actual measurement value is larger than the specific value, the cleaning process is considered to be not finished, and when the actual measurement value is not larger than the specific value, the cleaning process is considered to be finished.

The electromagnetic valves for the tube side are two-position three-way electromagnetic valves and respectively comprise a first electromagnetic valve 3, a second electromagnetic valve 4, a third electromagnetic valve 5 and a fourth electromagnetic valve 6; the first electromagnetic valve 3 and the third electromagnetic valve 5 are both two-inlet one-outlet electromagnetic valves, one inlet of the first electromagnetic valve 3 and one inlet of the third electromagnetic valve 5 are communicated with the input port of the steam pipeline 31, the other inlet of the first electromagnetic valve 3 and the other inlet of the third electromagnetic valve 5 are communicated with the input port of the condensation pipeline 32, and the outlets of the first electromagnetic valve 3 and the third electromagnetic valve 5 are communicated with the tube pass inlet 101 of the first heat exchanger 1; the second electromagnetic valve 4 and the fourth electromagnetic valve 6 are both one-inlet two-outlet electromagnetic valves, and inlets of the second electromagnetic valve 4 and the fourth electromagnetic valve 6 are communicated with a tube pass outlet 102 of the second heat exchanger 2; one of the outlets of the second solenoid valve 4 and the fourth solenoid valve 6 is communicated with a vapor recovery conduit 36, and the other outlet is communicated with a condensed water recovery conduit 35.

The shell-side electromagnetic valves are two-position three-way electromagnetic valves which are respectively a fifth electromagnetic valve 7 and a sixth electromagnetic valve 8, the fifth electromagnetic valve 7 is a one-inlet two-outlet electromagnetic valve, an inlet of the fifth electromagnetic valve 7 is communicated with an inlet of an ammonia gas pipeline 34, one outlet of the first electromagnetic valve 3C is communicated with a shell-side inlet 103 of the first heat exchanger 1, and the other outlet is communicated with a shell-side inlet 103 of the second heat exchanger 2; the sixth electromagnetic valve 8 is a two-inlet one-outlet electromagnetic valve, one inlet of the sixth electromagnetic valve 8 is communicated with the shell pass outlet 104 of the first heat exchanger 1, and the other inlet is communicated with the shell pass outlet 104 of the second heat exchanger 2; the outlet of the sixth solenoid valve 8 communicates with an ammonia return line 33.

The pressure sensors include a first pressure sensor 17, a second pressure sensor 18, a third pressure sensor 19, and a fourth pressure sensor 20; as shown in fig. 3, spherical pressure detection chambers 105 are provided at the shell-side inlet 103 and the shell-side outlet 104 of the first heat exchanger 1 and the second heat exchanger 2, respectively; the first pressure sensor 17 is positioned at the front end of the shell pass of the first heat exchanger 1, and the second pressure sensor 18 is positioned at the rear end of the shell pass of the first heat exchanger 1; the third pressure sensor 19 is positioned at the front end of the shell pass of the second heat exchanger 2, and the fourth pressure sensor 20 is positioned at the rear end of the shell pass of the second heat exchanger 2; the pressure sensor is a corrosion-resistant high-temperature gas pressure sensor, a sensing element of the pressure sensor is positioned in the pressure detection cavity 105, and a conversion element of the pressure sensor is positioned outside the pressure detection cavity 105.

The temperature sensors include a first temperature sensor 13, a second temperature sensor 14, a third temperature sensor 15 and a fourth temperature sensor 16; as shown in fig. 3, fluid temperature detection chambers 106 are respectively provided at the tube-side inlet 101 and the tube-side outlet 102 of the first heat exchanger 1 and the second heat exchanger 2; the first temperature sensor 13 is positioned at the front end of the tube pass of the first heat exchanger 1, and the second temperature sensor 14 is positioned at the rear end of the tube pass of the first heat exchanger 1; the third temperature sensor 15 is located at the front end of the tube side of the second heat exchanger 2, and the fourth temperature sensor 16 is located at the rear end of the tube side of the second heat exchanger 2.

The cold fluid in the condensing pipeline 32 is low-temperature condensed water, and the hot fluid in the steam pipeline 31 is high-temperature steam; the steam recovery pipeline 36 and the condensate recovery pipeline 35 are both communicated with the circulating water recovery tank 9; cooling water in the circulating water recovery tank 9 is used as a water source for producing steam after being refluxed by a reflux pump 10; the reflux pump 10 is electrically connected to the PLC controller 100, and the operation state thereof is controlled by the PLC controller 100.

The steam boiler 11 is communicated with the steam pipeline 31 through the single-way electromagnetic valve 12, and the single-way electromagnetic valve 12 controls fluid to flow into the steam pipeline 31 along the steam boiler 11; the steam boiler 11 and the one-way solenoid valve 12 are electrically connected to the PLC controller 100, and the operation state thereof is controlled by the PLC controller 100.

The first heat exchanger 1 and the second heat exchanger 2 are both tube type heat exchangers; the first heat exchanger 1 and the second heat exchanger 2 are used in a time-sharing mode, when one heat exchanger is used for cooling the fluid in the ammonia gas pipeline 34, the other heat exchanger is in a shell side cleaning state or an idle state.

This embodiment is through adopting parallel first heat exchanger 1 and second heat exchanger 2 for after certain heat exchanger in the negative pressure ammonia still equipment takes place to block up, the system can be directly with in the cooling process of the incondensable gas in the ammonia pipeline 34 switch to another heat exchanger, utilize steam boiler 11 to produce high-temperature steam simultaneously, let in high-temperature steam to the tube side of the heat exchanger after blockking up, heat the organic matter in the shell side in the tube side, reach and clean the effect. When the blocked heat exchanger is conducted again, the single-way electromagnetic valve 12 closes the steam pipeline 31; the cleaned heat exchanger is in an idle standby state; and after the other heat exchanger is blocked, switching the heat exchanger which can be cleaned again, and cleaning the latter heat exchanger. In the process, the flow of the negative pressure ammonia distillation process is not stopped, and the operation can be kept without stopping.

In this embodiment, the detection of the blocking state and the cleaning completion state of the first heat exchanger 1 and the second heat exchanger 2 is completed by the cooperation of the temperature sensor and the pressure sensor, and the accuracy and the reliability of the detection are extremely high. The detection principle is as follows: under normal use conditions, the flow rate of the fluid in the ammonia water pipeline is basically constant, when the fluid is condensed by the first heat exchanger 1 or the second heat exchanger 2, the fluid pressure at two ends of the shell side of the heat exchanger is approximately kept constant, meanwhile, the flow rate of the cold fluid in the tube side is approximately constant, and the temperature difference of the cold fluid at two ends of the tube side is approximately constant.

When partial organic matter in the shell pass of the heat exchanger is solidified, the shell pass of the heat exchanger is blocked, so that the flow velocity of fluid in the shell pass is changed, in this state, the gas pressure at the front end of the shell pass of the heat exchanger is obviously increased, the pressure at the rear end of the shell pass of the heat exchanger is obviously reduced, and the pressure difference is obviously increased due to the superposition of two phases. In addition, the condensation on the tube side is also reduced after the shell side is blocked, because the shell side fluid is reduced, the heat consumed on the tube side is reduced, and the temperature difference of the cold fluid at the two ends of the tube side is further reduced. If a specific pressure difference or temperature difference value is empirically selected, when the value condition is satisfied, it can be determined that the shell side of the heat exchanger is in a blocked state.

In the cleaning state, the pressure at the two ends of the shell pass is approximately equal, and the temperature of the hot fluid at the two ends of the tube pass is approximately equal, so that the temperature of the blocking object in the shell pass is consistent with that of the hot fluid, the blocked condensate is necessarily melted, and the shell pass can be judged to be cleaned completely.

In this example, high-temperature steam is selected as the hot fluid for heating, and low-temperature condensed water is used as the cold fluid, and the components of the two are consistent, so that pollution is avoided when switching is performed in the tube pass, and the fluid can be recycled after the cooling or heating process is completed. The scheme has obvious energy-saving and emission-reducing effects and is very environment-friendly.

Example 2

As shown in fig. 5, the present embodiment provides a cleaning control method, which is applied to the automatic cleaning device for a cooler in embodiment 1 and is controlled by the PLC controller 100 in the automatic cleaning device for a cooler, and includes the following processes:

s1, cooling the non-condensable gas by the first heat exchanger 1 in an initial state; the PLC 100 controls the fluid in the ammonia gas pipeline 34 to enter and exit along the shell pass of the first heat exchanger 1 through a fifth electromagnetic valve 7 and a sixth electromagnetic valve 8; the PLC 100 controls the cold fluid in the condensing pipeline 32 to enter and exit along the tube pass of the first heat exchanger 1 through the first electromagnetic valve 3 and the second electromagnetic valve 4, the steam boiler 11 does not work, the single-pass electromagnetic valve 12 is closed, and the shell pass and the tube pass of the second heat exchanger 2 are both in an idle state; and the operation is kept in the state.

S2, in the operating state of the above step, the PLC controller 100 detects the pressure in the pressure detection chambers 105 at the two ends of the shell pass of the first heat exchanger 1 through the first pressure sensor 17 and the second pressure sensor 18, and calculates the air pressure difference Δ p, and the PLC controller 100 detects the cold fluid temperature in the fluid temperature detection chambers 106 at the two ends of the tube pass of the first heat exchanger 1 through the first temperature sensor 13 and the second temperature sensor 14, and calculates the temperature difference Δ t.

S3, the PLC 100 makes the following judgment and decision according to the detection results of the air pressure difference delta p and the temperature difference delta t:

(1) when at least one condition of P0 being less than or equal to Δ P or T0 being more than or equal to Δ T is met, judging that the shell side of the heat exchanger A is not blocked; at this time, the normal working state of the first heat exchanger 1 is maintained;

(2) when the conditions that the delta P is more than P0 and the delta T is less than T0 are met, judging that the shell side of the heat exchanger A is obviously blocked;

wherein, T0 and P0 are specific values determined by technical experts in the field according to experience, in the process of gradually blocking the shell pass of the heat exchanger, the fluid pressure difference at two ends of the shell pass is gradually increased, the fluid temperature difference at two ends of the tube pass is gradually reduced, the minimum pressure difference value determined to be blocking is P0, and the maximum temperature difference value determined to be blocking is T0;

at this time, the following sweeping strategy is implemented: the fluid in the ammonia gas pipeline 34 is switched to enter and exit along the shell side of the second heat exchanger 2 under the control of a fifth electromagnetic valve 7 and a sixth electromagnetic valve 8; the steam boiler 11 works, and the single-way electromagnetic valve 12 is conducted; meanwhile, the first electromagnetic valve 3, the second electromagnetic valve 4, the third electromagnetic valve 5 and the fourth electromagnetic valve 6 are used for controlling, so that hot fluid in the steam pipeline 31 enters and exits along the tube pass of the first heat exchanger 1, and cold fluid in the condensation pipeline 32 enters and exits along the tube pass of the second heat exchanger 2.

S4, when the first heat exchanger 1 is in a cleaning state, the fluid temperatures t1 and t2 at the two ends of the tube side of the first heat exchanger 1 are continuously detected through the first temperature sensor 13 and the second temperature sensor 14, the pressures p1 and p2 at the two ends of the shell side of the first heat exchanger 1 are continuously monitored through the first pressure sensor 17 and the second pressure sensor 18, and the following judgment and decision are made according to the detection result:

(1) when the conditions that | P1-P2| is less than or equal to P1 and | T1-T2| is less than or equal to T1 are met, judging that the heat exchanger cleaning is finished;

(2) when the conditions that | P1-P2| is more than P1 or | T1-T2| is more than T1 are met, judging that the heat exchanger is not cleaned completely, and continuing to execute the heating and cleaning process; the one-way solenoid valve 12 on the control steam line 31 is closed.

Wherein P1 and T1 are specific values empirically determined by an expert in the field; the conditions for this value determination are: after cleaning is finished, the air pressure at the two ends of the shell pass and the temperature of the tube pass are in a state close to each other, and the values have certain difference, the maximum difference value of the values at the two ends after cleaning is determined to be P1 and T1, when the actual measurement value is larger than the specific value, the cleaning process is considered to be not finished, and when the actual measurement value is not larger than the specific value, the cleaning process is considered to be finished.

And S5, when the second heat exchanger 2 is in a cooling working state, performing detection, judgment and decision processes of steps S2 and S3 on the second heat exchanger 2, when the shell pass of the second heat exchanger 2 is detected to be in a blocked state, switching the non-condensable gas fluid in the ammonia gas pipeline 34 to the shell pass of the first heat exchanger 1 after cleaning is completed, and simultaneously performing a cleaning process of step S4 on the second heat exchanger 2.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.