At present, in flue gas desulfurization and anti corrosion, which anti corrosion materials are gener

At present, there are only two kinds of anticorrosive materials that can be competent in the desulfurization system in the world and China (not absolutely): one is the anticorrosive material of glass flake cement; The second is butyl rubber. Of course, there are other possibilities to achieve the purpose of embalming, but the cost performance is not the same.

It is worth mentioning here that the "glass flake cement" anti-corrosion material, now the domestic market is very chaotic, you ** search, there are, but really has the so-called "glass flake cement" anti-corrosion ability is not much, many of them say that they sell glass flake cement, but its anti-corrosion performance is far less, its main indicator is the impermeability is not good, the reason is that the formula is not good, most of them are paste-like things. The impermeability index of a really good glass flake cement material reaches below the minus 13-14 power of 10 (that is, the number is larger). If you want to find a qualified one, you can take a look at the "Nanjing Nature Company", we have used it, and there has been no maintenance for more than 10 years.

The flue anti-corrosion and wear-resistant coating is a KN17 polymer polymer material, and its main components are polymer and ceramic. Excellent wear resistance and corrosion resistance, high strength combined with metal substrates, no precipitation and delamination, acid and alkali resistance and hot water steam, suitable for the protection of high temperature wear and corrosion conditions, so it has strong corrosion resistance, the thickness of the flue anti-corrosion and wear-resistant coating is generally 5mm thick, which is quite different from the traditional anti-corrosion paint, and the long-term anti-corrosion of the flue anti-corrosion and wear-resistant coating is because of the thickness and wear resistance, because the KN17 flue anti-corrosion and wear-resistant coating contains ceramics.

It is generally high-temperature glass flakes.

The main equipment common in the desulfurization system is the main equipment such as absorption tower, flue, chimney, desulfurization pump, booster fan, etc., and the wet desulfurization process has the characteristics of strong medium corrosiveness, high temperature of the treated flue gas, large solid content of SO2 absorption liquid, strong abrasion, large anti-corrosion area of equipment, high quality requirements of construction technology, and difficult maintenance of anti-corrosion failure. Therefore, the corrosion control of the device has always been one of the key issues affecting the long-term safe operation of the device. The anti-corrosion of desulfurization mainly has the following aspects:

1. Application in absorption tower and chimney.

2. Dual-flow tray anti-corrosion protection.

A power plant installed a new dual-flow tray when it upgraded its scrubbers in 2010. Tests in 2011 showed deep pitting of the basal metal beneath the sediment area formed on the lower surface of the tray. Clean the sediment with high-pressure water and change the flow nozzle to try to control the fouling.

Corroded areas need to be protected by a coating to prevent further damage. The use of Aker-20 anti-corrosion coating to coat the old "bowl" that has been replaced by the tray is very effective.

3. Flue desulfurization and anti-corrosion protection.

Development of a new cathodic anti-corrosion system for the treatment of exhaust gases in combustion systems or for the protection of air pollution control facilities Effective control (current control) of high temperatures, extremely acidic corrosive environments (150, pH-2) thin coating solutions.

The flue gas contains sulfur and is inherently corrosive.

Wright. Ryder flue gas desulfurization.

Refers to the removal of sulfur oxides (SO2 and SO3) from flue gas or other industrial exhaust gases. Dry desulfurization dry flue gas desulfurization process This process for power plant flue gas desulfurization began in the early 80s and has the following advantages compared with conventional wet scrubbing processes: lower investment costs; The desulfurization products are dry and mixed with fly ash; There is no need to install a mist eliminator and reheater; The equipment is not easy to corrode, not easy to scale and clog.

Its disadvantages are: the utilization rate of absorbent is lower than that of wet flue gas desulfurization process; Poor economy when used in high-sulfur coal; The mixing of fly ash and desulfurization products may affect the comprehensive utilization. There are high requirements for the control of the drying process.

Spray desulfurization spray dry flue gas desulfurization process Spray dry flue gas desulfurization (referred to as dry FGD), the desulfurization process first jointly developed by the United States JOY company and Denmark Niroatomier company, was developed in the mid-70s and rapidly popularized and applied in the power industry. The process uses an atomized lime slurry in contact with the flue gas in a spray drying tower, and the lime slurry reacts with SO2 to form a dry solid reactant, which is finally collected by the dust collector together with the fly ash. In China, the intermediate test of rotary spray dry flue gas desulfurization has been carried out in Baima Power Plant in Sichuan Province, and some experience has been obtained, which provides a basis for the design of the optimal parameters of rotary spray dry flue gas desulfurization on 200 300MW units.

Coal ash desulfurization fly ash dry flue gas desulfurization technology Japan from 1985, research the use of fly ash as a desulfurization agent of dry flue gas desulfurization technology, to the end of 1988 to complete the industrial practical test, in early 1991 put into operation the first fly ash dry desulfurization equipment, the processing of flue gas volume of 644000nm h. Its characteristics: the desulfurization rate is as high as 60%, the performance is stable, and it has reached the performance level of general wet desulfurization; Low cost of desulfurizer; The water consumption is small, there is no need for drainage treatment and exhaust gas reheating, and the total equipment cost is lower than that of wet desulfurization1 4; Coal ash desulfurizer can be reused; There is no slurry, maintenance is easy, and the equipment system is simple and reliable.

The wet desulfurization FGD process is similar to the process, form and mechanism of wet flue gas desulfurization in all countries of the world, mainly using limestone (CaCO3), lime (CAO) or sodium carbonate (Na2CO3) and other slurries as detergents to wash the flue gas in the reaction tower, so as to remove SO2 in the flue gas. This process has a history of 50 years, after continuous improvement and perfection, the technology is relatively mature, and has the advantages of high desulfurization efficiency (90% 98%), large unit capacity, strong adaptability of coal types, low operating costs and easy by-products. According to the statistics of the United States Environmental Protection Agency (EPA), among the wet desulfurization units used in thermal power plants in the United States, the wet lime method accounts for 87% and the limestone method accounts for the two methods. Double-alkali method and sodium carbonate method.

In China's thermal power plants and steel mills, more than 90% of them adopt the wet lime limestone-gypsum flue gas desulfurization process. However, in Taiwan, Japan and other countries and regions with earlier desulfurization treatment, magnesium desulfurization is basically used, accounting for more than 95%.

At present, the anti-corrosion form commonly used in wet desulfurization is carbon steel lined with anti-corrosion materials, and the anti-corrosion materials used include rubber, glass fiber reinforced plastic, plastic and glass flake cement. Among them, glass flake cement is widely used.

Depending on the environment in which it is not used, the thickness of the glass flake cement varies. For parts with corrosion and abrasion at the same time, such as slurry pool and spray section, 4mm thick glass flakes are generally used, and reinforced with FRP on the outside, and 2mm thickness is generally used for other parts.

For the anti-corrosion of the flue, the net flue gas flue can be made of 2mm thick scales, and the yin and yang corners of the flue can be strengthened with FRP. For flues with higher temperatures, vinyl resin cement is generally used for resin.

The anti-corrosion of desulfurization equipment is related to what kind of materials are used for anti-corrosion, such as lining glue and lining glass flake cement, and the specific processes and precautions of anti-corrosion are not the same.

Taking the desulfurization tower lined with glass flake cement as an example, the cylinder of the desulfurization tower has been assembled and erected

1. Erect scaffolding;

2. The materials and tools have been prepared, and the construction electricity has been connected;

3. Substrate treatment, i.e., sandblasting;

4. Brush the primer;

5. Two or three times of cement;

6. Acceptance, such as side thickness, EDM detection, etc.

7. Clean up.

Sandblasting and rust removal! Scrape the glass scales.

1) Reasonable control of pH value.

2) It is a fatal mistake to choose a reasonable FGD flue gas inlet temperature, and choose the anti-corrosion lining that matches it, and choose the lining material that does not match the inlet flue gas temperature and the design temperature in the tower.

3) Strictly grasp the construction quality of anti-corrosion lining.

4) Due to the general on-site production of the absorption tower, it is necessary to ensure that the weld is fully welded in the process of absorbing tower production, the weld is smooth and smooth without defects, and the inner support and frame can not be made of angle steel, channel steel, I-beam, and round steel and square steel should be used, and the outer pipe can not be welded, and it should be connected with flanges.

5) Choose reasonable anti-corrosion materials. For the anti-corrosion of desulfurization waste gas treatment equipment, there are two main kinds, the first is to line the carbon steel body with anti-corrosion materials, and the second is to use corrosion-resistant alloy materials. The anti-corrosion lining is adopted, and the main materials are glass flake resin and rubber lining and FRP.