A composite boiler scale and corrosion inhibitor and its preparation method and application

Abstract

The invention provides an organic polymer scale inhibitor in a compound boiler scale and corrosion inhibitor. Particularly, poly(aspartic acid) has a good scale inhibition function on calcium carbonate and magnesium hydrate and has good biodegradability, no impurities are introduced into a boiler system, the clinical salt content of boiler water is increased, and the boiler blowdown rate is reduced; an organic polymer dispersant has a dispersion function and can stabilize calcium and magnesium ions in water and inhibit formation of silica scale, ferric scale, cooper scale and magnesium scale; the corrosion inhibitor has very high reductivity, a black Fe3O4 passivation film can be formed on the surface of the inner wall of a boiler, and the boiler is prevented from being further corroded. According to the compound boiler scale and corrosion inhibitor, negative influences of trisodium phosphate are eliminated, the discharge capacity is effectively reduced, and environment burden is reduced. A water treatment agent is applied to low-pressure, medium-pressure and high-pressure boilers by adjusting the pH value, inhibiting scaling and preventing corrosion, pH of boiler water is effectively buffered, the hydrogen brittleness phenomenon caused by excessive acid and alkali in the boiler is prevented, and boiler metal is protected.

Description

technical field [0001] The invention belongs to the field of chemical industry and water treatment, and in particular relates to a composite boiler scale and corrosion inhibitor, its preparation method and application. Background technique [0002] After the boiler has been in operation for a long time, scale and rust will inevitably appear on the inner wall of the boiler. After the boiler is scaled, the heat transfer performance of the heating surface is deteriorated, the heat released by the fuel combustion cannot be transferred to the boiler water in time, and a large amount of heat is taken away by the flue gas, causing the exhaust gas temperature to be too high and the loss of the exhaust gas to increase. Boiler thermal efficiency decreases and boiler fuel usage increases. A scaled boiler can easily cause overheating, deformation, bulging or even explosion on the heat transfer surface of the boiler during use. Scale containing high-priced iron can easily cause corrosi...

AI Technical Summary

Problems solved by technology

There are many technical problems in ordinary acid cleaning boilers: firstly, the acid is highly corrosive, which shortens the service life of the boiler; secondly, the amount of acid is not easy to control, and the amount of acid can not only remove the scale on the inner wall of the boiler, but also cause corrosion on the boiler wall; Thirdly, acid can only remove the scale of specific components, it is ineffective for insoluble scale, and the removal efficiency is low

[0004] At present, the boiler water system is treated with trisodium phosphate, which has obvious treatment shortcomings due to its own properties: (1) PO 4 3- There is no low-dose (threshold) effect on scale inhibition, so it has no inhibitory effect on scale and can only generate Ca 10 (OH) 2 (PO 4 ) 6 Water slag, which is formed according to stoichiometry, has a large amount of sewage, otherwise there will inevitably be supersaturated deposition of phosphate in the furnace, which will increase the tendency of entrainment; (2) PO 4 3- It is a scale-forming group, which cannot provide effective passivation protection for boilers under high temperature and high pressure, because the combined iron phosphate salt is the corrosive ion Fe 3+ Formed; (3) PO 4 3- The pH buffering capacity of the boiler water is limited, and the "temporary disappearance" of phosphate is prone to occur when the boiler load changes, resulting in excessive addition of sodium phosphate; (4) The generated salts are easily entrained into the steam system, causing steam Fouling of system turbines and corrosion of pipelines

However, aminotrimethylene phosphonic acid is used in this invention. During use, organic phosphine will increase the amount of pollutant discharge, which is not conducive to environmental protection.