Cleaning method for concentration system of phosphorus chemical production device

Abstract

The invention discloses a cleaning method for a concentration system of a phosphorus chemical production device.The method is characterized by comprising the following steps of (1) cyclic cleaning, (2) soaking, (3) mechanical cleaning and (4) emptying. The method has the advantages that dilute sulphuric acid is adopted to cyclically clean the concentration system, and scales in a circulating pump, a flash chamber and a foam remover can be removed; fluorosilicic acid is adopted to soak a graphite heat exchanger, most scales on the inner walls of tube nests fall off in the soaking process, the hardness of the scales remaining on the inner walls of the tube nests can be reduced under the soaking effect, then the scales on the graphite heat exchanger can be completely removed through mechanical flushing, mechanical cleaning is performed after acid pickling and soaking, and the comprehensive cleaning effect is good; and the fluosilicic acid is adopted only in the soaking process of the graphite heat exchanger and does not pass through the circulating pump and subsequent equipment, the fluosilicic acid can be thoroughly prevented from being in contact with the circulating pump, the circulating pump is prevented from being corroded, the service life of the equipment is prolonged, and the maintenance cost is reduced.

Description

Technical field: [0001] The invention relates to the technical field of phosphorus chemical production, in particular to a method for cleaning a concentration system of a phosphorus chemical production device. Background technique: [0002] The phosphoric acid concentration system of Phosphorus Chemical mainly includes a circulating pump, graphite heat exchanger, flash chamber and demister. During the concentration process, impurities in dilute acid are precipitated as the temperature rises, and the precipitated substance is mainly anhydrous CaSO 4 , fluorosilicate and silica gel, adhere to the surface of the tube-and-tube graphite heat exchanger and flash evaporator to form scales, and as the production runs, the scales fall off and enter the system, blocking the tubes, affecting the production load and reducing the production cycle . Among them, the graphite heat exchanger is the main equipment of the concentration system in the production of dihydrate wet-process phospho...

AI Technical Summary

Problems solved by technology

The general cleaning method cannot thoroughly clean and descale. After the cleaning, there will usually be scaling on the inner wall of the graphite heat exchanger tubes, and with the prolongation of the production time, the scale that cannot be cleaned with acid solution will also be removed. The thicker and thicker it is, 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.

[0003] Patent CN200510003132.0 discloses a descaling method for phosphoric acid concentration heat exchangers. The special cleaning solution used is composed of fluosilicic acid solution, organic phosphonic acid buffer and film-forming substances. The main function of the membrane material is to slow down the corrosion of fluosilicic acid on the 904L material of the circulating pump during the cycle cleaning process, and the cost of the cleaning liquid is high; and the cleaning process is to first use a high-pressure water gun to clean the heat exchanger for about 12 hours, and then use the cleaning liquid to clean the heat exchanger. After cleaning at 60°C for 12 hours, clean and clean for a total of about 40 hours. This method uses a high-pressure water gun to clean for 12 hours before cleaning. The labor intensity of the staff is high, and the mechanical cleaning efficiency is low and the effect is poor because of the hard scaling. ;The cleaning cycle is extended from once every 15 days to once every 20 days, and the extension time is only 5 days. Generally speaking, this method is costly, labor-intensive, and the cleaning cycle extension effect is not obvious

[0004] Patent CN201110297696.5 discloses a method for cleaning the wet-process phosphoric acid concentration heat exchanger, which uses fluosilicic acid, concentrated phosphoric acid, and water as the cleaning agent, and does not fully consider the corrosion of the metal circulating pump by fluosilicic acid, resulting in a cycle Reduced pump life cycle increases maintenance costs

[0005] Patent CN201110409331.7 discloses a method for cleaning graphite heat exchanger tube scaling, which uses hydrochloric acid, fluorosilicic acid, sodium hydroxide, and sodium carbonate solutions for cleaning. Corrosion of metal pumps. Corrosion of metal circulating pumps reduces the service life of circulating pumps and increases maintenance costs. The entry of sodium ions into the system will accelerate the scaling of the system pipes and affect the cleaning effect. The cleaning step is the first water flushing -The first pressure test-acid washing-the second water washing-the second pressure test-alkali washing-the third water washing-the third pressure test, the cleaning takes about 3 days, and the time is long

[0006] Patent CN201910248731.0 discloses a cleaning method for the concentration system used in the wet-process phosphoric acid purification process. Sulfuric acid, fluosilicic acid, pickling buffer, sodium molybdate, penetrant, sulfamic acid and other cleaning solutions are used, and the solution configuration is difficult. High cost and difficult to operate