阅读说明：本技术 磷化工生产装置浓缩系统清洗方法 (Cleaning method for concentration system of phosphorus chemical production device ) 是由 卢涛 李崇贵 朱明芳 廖德春 路胜男 李小伟 李兴文 伞吉洋 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种磷化工生产装置浓缩系统清洗方法,其特征在于,其包括以下步骤：(1)循环清洗；(2)浸泡；(3)机械清理；(4)排空。优点：采用稀硫酸对浓缩系统进行循环清洗,可将循环泵、闪蒸室和除沫器中的结垢物清除；采用氟硅酸对石墨换热器进行浸泡,列管内壁上的大部分结垢物在浸泡过程中脱落,留存在列管内壁上的结垢物的硬度也会在浸泡作用下降低,之后再采用机械冲洗即可将石墨换热器流感上的结垢物全部去除,经过酸洗、浸泡后再机械清洗,综合清洗效果好。只在石墨换热器浸泡过程中采用了氟硅酸,氟硅酸不经过循环泵及后续设备,可彻底杜绝氟硅酸与循环泵接触,避免腐蚀循环泵,延长设备使用寿命,降低维护成本。(The invention discloses a cleaning method for a concentration system of a phosphorus chemical production device, which is characterized by comprising the following steps of: (1) circularly cleaning; (2) soaking; (3) mechanical cleaning; (4) and (6) emptying. The advantages are that: the concentrated system is circularly cleaned by dilute sulfuric acid, and scale substances in a circulating pump, a flash evaporation chamber and a demister can be removed; the graphite heat exchanger is soaked by fluosilicic acid, most of scaling substances on the inner wall of the tube nest fall off in the soaking process, the hardness of the scaling substances remained on the inner wall of the tube nest is reduced under the soaking effect, then the scaling substances on the influenza of the graphite heat exchanger can be completely removed by mechanical washing, and the graphite heat exchanger is mechanically cleaned after acid washing and soaking, so that the comprehensive cleaning effect is good. Only adopt fluosilicic acid at graphite heat exchanger soaking in-process, fluosilicic acid does not pass through circulating pump and follow-up equipment, can thoroughly stop fluosilicic acid and circulating pump contact, avoids corroding the circulating pump, extension equipment life reduces the maintenance cost.)

1. The cleaning method of the concentration system of the phosphorus chemical production device is characterized by comprising the following steps:

(1) circulation cleaning

Injecting the cleaning acid liquor into a concentration system for cyclic cleaning, controlling the temperature of the cleaning acid liquor to be 78-85 ℃, controlling the time of the cyclic cleaning to be 18-26 h, and emptying the cleaning acid liquor;

(2) soaking

After the cleaning acid liquid is emptied, adding a soaking acid liquid into the graphite heat exchanger tube nest, controlling the temperature of the soaking acid liquid to be 78-85 ℃, soaking the graphite heat exchanger tube nest for 7-15 hours, and emptying the soaking acid liquid;

(3) mechanical cleaning

After the soaking acid liquid is emptied, dredging and washing the tube array of the graphite heat exchanger for 3-6 hours by adopting mechanical equipment;

(4) evacuation of the liquid

And after the mechanical cleaning is finished, emptying sundries at the bottom of the graphite heat exchanger to finish the cleaning of the concentration system.

2. The method for cleaning the concentration system of the phosphorus chemical production device as claimed in claim 1, wherein in the step (1), the cleaning acid solution is dilute sulfuric acid.

3. The cleaning method for the concentration system of the phosphorus chemical production device according to claim 2, wherein the concentration of the dilute sulfuric acid is 6-10%.

4. The method for cleaning the concentration system of the phosphorus chemical production device according to any one of claims 1 to 3, wherein the soaking acid is fluosilicic acid.

5. The cleaning method for the concentration system of the phosphorus chemical production device according to claim 4, wherein the concentration of the fluosilicic acid is 10-13%.

6. The cleaning method for the concentration system of the phosphorus chemical production device as claimed in claim 5, wherein in the step (2), the soaking acid solution is replaced every 4-7 hours after the soaking is started.

7. The cleaning method for the concentration system of the phosphorus chemical production device as claimed in claim 1, 2, 3, 5 or 6, wherein during the soaking in the step (2), compressed air is fed into the graphite heat exchanger to stir the soaking acid liquor.

8. The method for cleaning a concentration system of a phosphorus chemical production device according to claim 1, 2, 3, 5 or 6, wherein the mechanical equipment used in the step (3) is a high pressure cleaning machine.

9. The method for cleaning a concentration system of a phosphorus chemical production device according to claim 7, wherein the mechanical equipment used in the step (3) is a high pressure cleaner.

The technical field is as follows:

the invention relates to the technical field of phosphorus chemical industry production, in particular to a cleaning method for a concentration system of a phosphorus chemical industry production device.

Background art:

the phosphoric acid concentration system for phosphorus chemical industry mainly comprises a circulating pump, a graphite heat exchanger, a flash evaporation chamber and a demister, wherein in the concentration process, impurities in dilute acid are separated out along with the rise of temperature, and the separated substances are mainly anhydrous CaSO₄Fluorosilicate and silica gel are adhered to the surfaces of the tubular graphite heat exchanger and the flash evaporator to form scaling substances, and the scaling substances fall off along with the operation of production to enter a system to block the tubular graphite heat exchanger, so that the production load is influenced, and the production period is shortened. Wherein, the graphite heat exchanger is the main equipment of the concentration system in the production of the phosphoric acid by the dihydrate wet method, and various ions (such as Na) dissolved in the phosphoric acid by the wet method are dissolved along with the increase of the concentration of the phosphoric acid when the phosphoric acid is concentrated₂O、K₂O) and other acid insoluble substances are reduced at a very high speed to separate out precipitates, such as salts of calcium, magnesium, iron and the like, and the precipitates are often adhered to the inner wall of the tube nest of the concentrated graphite heat exchanger to form a hard scale shell. The scale cannot be thoroughly cleaned and removed by using a common cleaning method, after cleaning is finished, the inner wall of the tube array of the graphite heat exchanger usually contains scale forming substances, and along with the lengthening of production time, the scale which cannot be cleaned and removed by cleaning with an acid solution is accumulated more and more thickly, so that the heat transfer efficiency is seriously reduced, the fluid resistance is increased, the production capacity of the graphite heat exchanger is reduced, and the production cost is increased.

Patent CN200510003132.0 discloses a descaling method for a phosphoric acid concentration heat exchanger, wherein a specially-made cleaning solution is composed of a fluorosilicic acid solution, an organic phosphonic acid buffering agent and a film-forming substance, the organic phosphonic acid buffering agent and the film-forming substance mainly play a role in slowing down corrosion of fluosilicic acid on 904L materials of a circulating pump in a circulating cleaning process, and the cost of the cleaning solution is high; in addition, the cleaning process is that a high-pressure water gun is firstly adopted to clean the heat exchanger for about 12 hours, then cleaning liquid is used for cleaning for 12 hours at 60 ℃, and then cleaning and cleaning are carried out for about 40 hours, the method adopts the high-pressure water gun to clean for 12 hours before cleaning, the labor intensity of workers is high, and the mechanical cleaning efficiency is lower and the effect is poor because the scale is hard; the cleaning period is prolonged from once every 15 days to once every 20 days for only 5 days, and the method has high cost, high labor intensity and insignificant effect of prolonging the cleaning period.

Patent CN201110297696.5 discloses a method for cleaning a wet-process phosphoric acid concentration heat exchanger, which adopts the mixing of fluosilicic acid, concentrated phosphoric acid and water as a cleaning agent, and does not fully consider the corrosion problem of the fluosilicic acid to a metal circulating pump, thereby reducing the service cycle of the circulating pump and increasing the maintenance cost.

The patent CN201110409331.7 discloses a graphite heat exchanger tube nest scaling cleaning method, which adopts hydrochloric acid, fluosilicic acid, sodium hydroxide and sodium carbonate solution for cleaning, the cost of the hydrochloric acid and the sodium hydroxide is high, the corrosion problem of chloride ions to a stainless steel metal pump and the corrosion problem of a metal circulating pump are not considered, the service cycle of the circulating pump is reduced, and the maintenance cost is increased; the sodium ions entering the system can accelerate the scaling of the system pipeline and influence the cleaning effect; the cleaning step comprises the steps of primary water flushing, primary pressure testing, acid cleaning, secondary water washing, secondary pressure testing, alkali cleaning, tertiary water washing and tertiary pressure testing, and the cleaning time is about 3 days and is long.

Patent CN201910248731.0 discloses a cleaning method of a concentration system for wet-process phosphoric acid purification process, which adopts cleaning solutions such as sulfuric acid, fluosilicic acid, acid pickling buffer, sodium molybdate, penetrant, sulfamic acid and the like, and the solutions are difficult to prepare, high in cost and difficult to operate.

The invention content is as follows:

the invention aims to provide a cleaning method of a concentration system of a phosphorus chemical production device, which has a good cleaning effect.

The invention is implemented by the following technical scheme: the cleaning method of the concentration system of the phosphorus chemical production device comprises the following steps:

(1) circulation cleaning

Injecting the cleaning acid liquor into a concentration system for cyclic cleaning, controlling the temperature of the cleaning acid liquor to be 78-85 ℃, controlling the time of the cyclic cleaning to be 18-26 h, and emptying the cleaning acid liquor;

(2) soaking

After the cleaning acid liquid is emptied, adding a soaking acid liquid into the graphite heat exchanger tube nest, controlling the temperature of the soaking acid liquid to be 78-85 ℃, soaking the graphite heat exchanger tube nest for 7-15 hours, and emptying the soaking acid liquid;

(3) mechanical cleaning

After the soaking acid liquid is emptied, dredging and washing the tube array of the graphite heat exchanger for 3-6 hours by adopting mechanical equipment;

(4) evacuation of the liquid

And after the mechanical cleaning is finished, emptying sundries at the bottom of the graphite heat exchanger.

Further, in the step (1), the cleaning acid solution is dilute sulfuric acid.

Furthermore, the concentration of the dilute sulfuric acid is 6-10%.

Further, the soaking acid liquid is fluosilicic acid.

Further, the concentration of the fluosilicic acid is 10-13%.

Further, in the process of the step (2), after soaking is started, replacing the soaking acid liquor every 4-7 hours.

Further, in the soaking process in the step (2), compressed air is fed into the graphite heat exchanger to stir the soaking acid liquor.

Further, the mechanical equipment adopted in the step (3) is a high-pressure cleaning machine.

The invention has the advantages that: the concentrated system is circularly cleaned by dilute sulfuric acid, and scale substances in a circulating pump, a flash evaporation chamber and a demister can be removed; soaking a concentrated main device, namely a graphite heat exchanger, by adopting a fluosilicic acid solution, so that most of scaling substances on the inner wall of the tube nest fall off in the soaking process, and the hardness of the scaling substances remained on the inner wall of the tube nest is reduced under the soaking action; the soaked inner wall of the tube nest is mechanically cleaned by a high-pressure cleaning machine, scale substances with reduced hardness on the inner wall of the tube nest can be further washed and fall to the bottom of the graphite heat exchanger, and the tube nest is mechanically cleaned after acid washing and soaking, so that the comprehensive cleaning effect is good. Only two acids of dilute sulfuric acid and fluosilicic acid are used in the whole cleaning process, and the two acids do not need to be mixed, so that the solution is easy to prepare and has low difficulty; fluosilicic acid is a byproduct, only partial concentrated sulfuric acid needs to be purchased to prepare dilute sulfuric acid, and the cleaning cost is low. And only the fluosilicic acid is adopted in the soaking process of the graphite heat exchanger, and the fluosilicic acid does not pass through a circulating pump and subsequent equipment, so that the contact between the fluosilicic acid and the circulating pump can be thoroughly avoided, the circulating pump is prevented from being corroded, the service life of the equipment is prolonged, and the maintenance cost is reduced.

The specific implementation mode is as follows:

example 1: the cleaning method of the concentration system of the phosphorus chemical production device comprises the following steps:

(1) circulation cleaning

Injecting a cleaning acid solution into a concentration system for circular cleaning, wherein the cleaning acid solution is dilute sulfuric acid, and the concentration of the dilute sulfuric acid is 6%; controlling the temperature of the cleaning acid liquor at 78 ℃, controlling the time of the circular cleaning at 26h, and emptying the cleaning acid liquor.

(2) Soaking

After the cleaning acid liquid is emptied, adding a soaking acid liquid into the tube of the graphite heat exchanger, wherein the soaking acid liquid is fluosilicic acid, and the concentration of the fluosilicic acid is 10%; the temperature of the soaking acid liquid is controlled to be 78 ℃, the graphite heat exchanger tube nest is soaked for 15 hours, the soaking acid liquid is replaced every 7 hours, in addition, compressed air is sent into the graphite heat exchanger in the soaking process to stir the soaking acid liquid, scaling on the inner wall of the tube nest is accelerated to fall off, the soaking and pneumatic stirring are combined, scaling on the inner wall of the tube nest is reduced, india scaling on the inner wall of the influenza is reduced, further, the subsequent mechanical cleaning difficulty is reduced, and after the soaking is finished, the soaking acid liquid is emptied.

(3) Mechanical cleaning

After the soaking acid liquid is emptied, the graphite heat exchanger tube array is dredged and washed for 3 hours by a high-pressure cleaning machine so as to lead the scales attached to the inner wall of the tube array to fall off.

(4) Evacuation of the liquid

And after the mechanical cleaning is finished, emptying sundries at the bottom of the graphite heat exchanger to finish the cleaning of the concentration system.

Example 2: the cleaning method of the concentration system of the phosphorus chemical production device comprises the following steps:

(1) circulation cleaning

Injecting a cleaning acid solution into a concentration system for circular cleaning, wherein the cleaning acid solution is dilute sulfuric acid, and the concentration of the dilute sulfuric acid is 8%; controlling the temperature of the cleaning acid solution at 82 ℃, controlling the time of the circular cleaning at 22h, and emptying the cleaning acid solution.

(2) Soaking

After the cleaning acid liquid is emptied, adding a soaking acid liquid into the tube of the graphite heat exchanger, wherein the soaking acid liquid is fluosilicic acid, and the concentration of the fluosilicic acid is 12%; the temperature of the soaking acid liquid is controlled to be 80 ℃, the shell and tube of the graphite heat exchanger are soaked for 10 hours, the soaking acid liquid is replaced once every 5 hours, in addition, compressed air is sent into the graphite heat exchanger in the soaking process to stir the soaking acid liquid, the scaling on the inner wall of the shell and tube is accelerated to fall off, the soaking and pneumatic stirring are combined, the scaling on the inner wall of the shell and tube is reduced, the india scaling on the inner wall of the influenza is reduced, the subsequent mechanical cleaning difficulty is further reduced, and after the soaking is finished, the soaking acid liquid is emptied.

(3) Mechanical cleaning

After the soaking acid liquid is emptied, the graphite heat exchanger tube array is dredged and washed for 4 hours by a high-pressure cleaning machine so as to lead the scales attached to the inner wall of the tube array to fall off.

(4) Evacuation of the liquid

And after the mechanical cleaning is finished, emptying sundries at the bottom of the graphite heat exchanger to finish the cleaning of the concentration system.

Example 3: the cleaning method of the concentration system of the phosphorus chemical production device comprises the following steps:

(1) circulation cleaning

Injecting a cleaning acid solution into a concentration system for circular cleaning, wherein the cleaning acid solution is dilute sulfuric acid, and the concentration of the dilute sulfuric acid is 10%; controlling the temperature of the cleaning acid liquor at 85 ℃, controlling the time of the circular cleaning at 18h, and emptying the cleaning acid liquor.

(2) Soaking

After the cleaning acid liquid is emptied, adding a soaking acid liquid into the tube of the graphite heat exchanger, wherein the soaking acid liquid is fluosilicic acid, and the concentration of the fluosilicic acid is 13%; the temperature of the soaking acid liquid is controlled to be 85 ℃, the graphite heat exchanger tube nest is soaked for 7 hours, the soaking acid liquid is replaced every 3.5 hours, in addition, compressed air is sent into the graphite heat exchanger in the soaking process to stir the soaking acid liquid, scaling on the inner wall of the tube nest is accelerated to fall off, the soaking and pneumatic stirring are combined, scaling on the inner wall of the tube nest is reduced, india scaling on the inner wall of the influenza is reduced, further, the subsequent mechanical cleaning difficulty is reduced, and after the soaking is finished, the soaking acid liquid is emptied.

(3) Mechanical cleaning

After the soaking acid liquid is emptied, the graphite heat exchanger tube array is dredged and washed for 6 hours by a high-pressure cleaning machine so as to lead the scales attached to the inner wall of the tube array to fall off.

(4) Evacuation of the liquid

And after the mechanical cleaning is finished, emptying sundries at the bottom of the graphite heat exchanger to finish the cleaning of the concentration system.

According to the cleaning method, dilute sulfuric acid is adopted to circularly clean the concentration system, and scaling substances in a circulating pump, a flash evaporation chamber and a demister can be removed; then, soaking the concentrated main equipment, namely the graphite heat exchanger, by using fluosilicic acid, wherein part of scaling substances on the inner wall of the tube nest fall off in the soaking process, the hardness of the scaling substances remained on the inner wall of the tube nest is also reduced under the soaking action, and the scaling substances can fall off completely through mechanical cleaning; then, mechanically cleaning the inner wall of the tube array by using a high-pressure cleaning machine, and further washing and dropping scale substances with reduced hardness on the inner wall of the tube array to the bottom of the graphite heat exchanger; and finally, emptying sundries at the bottom of the graphite heat exchanger.

Only two acids of dilute sulfuric acid and fluosilicic acid are used in the whole cleaning process, and the two acids do not need to be mixed, so that the solution is easy to prepare and has low difficulty; fluosilicic acid is a byproduct, and dilute sulfuric acid is prepared by purchasing concentrated sulfuric acid, so that the cleaning cost is low.

Moreover, only the fluosilicic acid is adopted in the soaking process of the graphite heat exchanger, and the fluosilicic acid does not pass through a circulating pump and subsequent equipment, so that the contact between the fluosilicic acid and the circulating pump can be thoroughly avoided, the circulating pump is prevented from being corroded, the service life of the equipment is prolonged, and the maintenance cost is reduced; the whole cleaning process is about 40 hours, the cleaning time is short, the operation period of the cleaned system is prolonged to 45 days, and the effect is remarkable.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.