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Chemical cleaning method of heat exchanger

A chemical cleaning and heat exchanger technology, applied in the field of heat exchanger cleaning, can solve the problems of equipment substrate corrosion, difficult to remove hard scale, long cleaning cycle, etc., and achieve the effects of low corrosion, acid mist suppression, and short cleaning time

Active Publication Date: 2014-12-24
ENERGY RESOURCES INST HEBEI ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional downtime cleaning pickling method directly adopts the method of strong acid and corrosion inhibitor, the hard scale is difficult to remove, and the cleaning time is long, generally more than 10 hours, which seriously corrodes the equipment substrate
The non-stop online cleaning method is less corrosive to the equipment, but the cleaning cycle is longer, generally about 20 days

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Cooling water carbon steel heat exchanger cleaning, scale 1.5~2.0mm, average scale of sample tube is 1857.4g / m 2 .

[0017] The soaking agent used is: maleic acid-acrylic acid copolymer solution and dodecyl dimethyl benzyl ammonium chloride aqueous solution. The acid used is: hydrochloric acid. The corrosion inhibitors are: hexamethylenetetramine and thiourea. Cleaning temperature: 22.5-27.2°C, soaking for 1 hour, cleaning time: 2 hours. After cleaning, the surface of the carbon steel is as bright as new, the cleaning degree is more than 90%, and the corrosion rate is 1.56g / m 2 h, much less than the national standard corrosion rate index 5g / m 2 h.

[0018] Use potions

[0019] Dodecyl dimethyl benzyl ammonium chloride

Embodiment 2

[0021] Cooling water stainless steel heat exchanger cleaning, the scale layer is 1.0~1.1mm, the average scale of the sample tube is 1128.3g / m 2 .

[0022] The soaking agent used is: hydroxyethylene diphosphonic acid, cetyl dimethyl (2-sulfite) ethyl ammonium. The acid used is: sulfamic acid. The corrosion inhibitor is hexamethylenetetramine and thiourea. Cleaning temperature: 24.9~29.7℃, soaking for 1 hour, cleaning time: 3 hours. After cleaning, the surface of stainless steel is as bright as new, and the scale is clean. The degree of cleaning is above 95%, and the corrosion rate is 0.26g / m. 2 h, much less than the national standard corrosion rate index 1.5g / m 2 h.

[0023] Use potions

Embodiment 3

[0025] Cooling water brass heat exchanger cleaning, the scale layer is 0.5~0.6mm, the average scale of the sample tube is 489.4g / m 2 .

[0026] The soaking agent used is: acrylic acid-hydroxypropyl acrylate and dodecyldimethylbenzylammonium chloride aqueous solution. The acid used is: sulfuric acid. The corrosion inhibitor is hexamethylenetetramine and thiourea. Cleaning temperature: 20.1~25.4℃, soaking for 1 hour, cleaning time: 2.5 hours. After cleaning, the brass surface is as bright as new, the cleaning degree is more than 90%, and the corrosion rate is 0.37g / m 2 h, much less than the national standard corrosion rate index 1.5g / m 2 h.

[0027] Use potions

[0028] Thiourea

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Abstract

The invention provides a chemical cleaning method of a heat exchanger, which is short in cleaning time and low in corrosive property. The chemical cleaning method comprises the following steps: (1) configuring a pipe for the heat exchanger in the shutdown state of a cooling system, and connecting a liquid preparation tank and a cleaning pump to the outside of the configured pipe to form a closed system for pump circulation cleaning; (2) adding soaking liquid obtained by mixing a dispersion chelating agent with a stripping agent into the closed system in the step (1), and soaking the heat exchanger for 1 hour; (3) selecting corresponding acid and corrosion inhibitor according to the material of the heat exchanger, adding the acid and the corrosion inhibitor into the soaking liquid of the closed system in the step (1) to form cleaning liquid, performing pump circulation acid-washing for 2-3 hours, and properly prolonging or shortening the acid-washing time according to the scale formation thickness; and (4) adjusting the pH value of the cleaning liquid in the step (3) to be about 7 by using sodium hydroxide, discharging, and flushing to finish the cleaning process.

Description

Technical field [0001] The invention relates to a heat exchanger cleaning method, in particular to a heat exchanger chemical cleaning method. Background technique [0002] Petroleum, chemical, electric power, metallurgy, pharmacy, printing and dyeing industries have circulating cooling systems. Cooling water is continuously circulated in the circulating system. Due to the rise of water temperature and the evaporation and concentration of water, the adhesion of sediments will occur, especially when changing On the heat transfer surface of the heat exchanger, various salts dissolved in natural water, such as bicarbonate, sulfate, chloride, silicate, etc., can easily reach saturation and crystallize out of the water, firmly attached to the heat transfer On the surface. This not only greatly reduces the heat transfer efficiency, but also causes under-scaling corrosion and microbial growth due to fouling, which will eventually lead to corrosion and perforation of the pipe wall and le...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23G1/06C23G1/08
Inventor 田彩利兰朋娜刘振法张利辉李晓辉
Owner ENERGY RESOURCES INST HEBEI ACADEMY OF SCI
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