Introduction of the hottest ammonia desulfurizatio

2022-08-13
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Introduction to ammonia desulfurization technology

the PPS market in Europe is expanding rapidly. The desulfurization process is based on the basic mechanism of ammonia reacting with SO2 and water to form desulfurization products, mainly including wet ammonia method, electron beam ammonia method, pulse corona ammonia method, simple ammonia method, etc

1. Electron beam ammonia method (EBA method) and pulse corona ammonia method (PPCP method)

electron beam ammonia method and pulse corona ammonia method respectively irradiate the flue gas injected into water and ammonia and cooled to about 70 ℃ with electron beam and pulse corona. Under the action of strong electric field, some flue gas molecules are ionized and become high-energy electrons, which activate, crack and ionize other flue gas molecules, producing Oh, O, HO2 and other active particles and free radicals. In the reactor, SO2 and no in the flue gas are oxidized by active particles and free radicals to high-order oxides SO3 and NO2, which meet with H2O in the flue gas to form H2SO4 and HNO3. When NH3 or other neutralizers are injected, aerosols of (NH4) 2so4/nh4no3 are generated, and then collected by the dust collector. The electric field of the flue gas desulfurization and denitration reactor with pulse corona discharge also has the function of dust removal

the energy consumption and efficiency of these two ammonia methods need to be improved, and the main equipment such as high-power electron beam accelerator and pulse corona generator are still in the development stage

2. Simple ammonia method

the commercialized simple ammonia method includes ts, PS ammonia desulfurization process, etc., which mainly uses the rapid reaction between H2O, NH3 and SO2 under gas phase conditions to design a simple reaction device. Strictly speaking, the simple ammonia method is a non recoverable ammonia method, and most of the products of its desulfurization sensor are unstable ammonium sulfite in aerosol state, which is very difficult to recover, and the economy of ammonia method cannot be reflected; And after the desulfurization products are evacuated with the flue gas, SO2 will be partially decomposed to form secondary pollution. Therefore, this process can only be used in devices with low environmental requirements, waste ammonia source and no long-term operation

3, wet ammonia method

in recent years, wet ammonia method is a relatively mature and industrialized ammonia desulfurization process, and wet ammonia method is both desulfurization and denitrification. The wet ammonia process is generally divided into three steps: desulfurization and absorption, intermediate product treatment, and by-product manufacturing. According to different processes and by-products, wet ammonia method can be divided into ammonia ammonium sulfate fertilizer method, ammonia ammonium phosphate fertilizer method, ammonia acid method, ammonia ammonium sulfite method, etc

(1) absorption process:

desulfurization absorption process is the core of ammonia flue gas desulfurization technology, which is based on the reaction of SO2 and NH3 in aqueous solution:

SO2 + H2O + xnh3 = (NH4) xh2-xso3 (1)

ammonium sulfite intermediate product is obtained. Where, x=1.2-1.4

directly making ammonium sulfite into products is ammonium sulfite method

(2) intermediate product treatment

the treatment of intermediate products is mainly divided into two categories: direct oxidation and acidolysis

a) direct oxidation - ammonia ammonium sulfate fertilizer method

in the multi-functional desulfurization tower, the air is blown in to oxidize ammonium sulfite into ammonium sulfate, and the reaction is:

(NH4) xh2-xso3+1/2o2 + (2-x) nh3= (NH4) 2SO4 (2)

b) acidolysis - ammonia acid method

acidolysis the desulfurization product ammonium sulfite with sulfuric acid, phosphoric acid, nitric acid and other acids to generate the corresponding ammonium salt and gas sulfur dioxide. The reaction is as follows:

(NH4) xh2-xso3+x/2h2so4=x/2 (NH4) 2so4+so2+h2o (3)

(NH4) xh2-xso3+xhno3=xnh4no3+so2+h2o (4)

(NH4) xh2-xso3+x/2h3po4=x/2 (NH4) 2hpo4+so2+h2o (5)

(3) by product manufacturing

intermediate after treatment, the product forms ammonium salt and gaseous sulfur dioxide. Ammonium salt is sent to the fertilizer making device to make finished nitrogen fertilizer or compound fertilizer; Gaseous sulfur dioxide can be used not only to produce liquid sulfur dioxide, but also to send it to sulfuric acid plant to produce sulfuric acid. The sulfuric acid produced can be used to produce phosphoric acid, phosphate fertilizer, etc

4. Denitrification effect of wet ammonia method

wet ammonia method can play a certain denitrification effect while desulfurization

the reaction formula is:

2No + 02 = 2n02

2n02 + H20 = hn03 + hn02

NH3 + hn03 = hn4no3 + H2O

NH3 + hn02 = hn4no2 + H2O

4 (hn4) 2so3 + 2n02 = N2 + 4 (hn4) 2SO4

the wet ammonia desulfurization process system is generally composed of

ammonia washing desulfurization is worthy of customers' trust. Your process equipment is mainly composed of desulfurization.Washing system, flue gas system, ammonia storage system Ammonium sulfate production system (if it is not ammonia ammonium sulfate law, it is the by-product manufacturing system corresponding to its process), etc. The core equipment is desulfurization scrubber

several wet ammonia desulfurization processes:

(1) Walther ammonia process

wet ammonia desulfurization process was first developed by Krupp kroppers in the 1970s and 1980s. The flue gas after dust removal first passes through the heat exchanger, enters the washing tower from above, and flows down with ammonia (25%). Ammonia falls into the pool, and is pumped into the absorption tower to circulate and spray the flue gas. The flue gas enters a high-efficiency washing tower after passing through the demister to wash out the residual salt solution. Finally, the clean flue gas heated by the heat exchanger is discharged into the chimney

(2) amasox ammonia process

one of the main problems encountered by the traditional ammonia process is that the aerosol problem in the purified flue gas has not been solved. Nengis Bischoff transformed and improved the traditional ammonia process into amasox process. The main improvement is to change the traditional multi tower into a single tower with compact structure, and install a wet electric demister in the tower to solve the aerosol problem

(3) ge ammonia process

in the 1990s, Ge in the United States also developed the ammonia process and built a 500MW industrial demonstration unit in Kenosha power plant in Wisconsin. The process flow is as follows: the flue gas after dust removal is led out from the back of the boiler of the power plant, enters the cooling device after passing through the heat exchanger, and then enters the high-pressure spray water mist for cooling and dust removal (removing the residual flue gas), which is cooled to the clean flue gas close to the saturation and dew point temperature, and then enters the absorption washing tower. Two sections of absorption and washing layers are arranged in the absorption tower, so that the washing liquid and flue gas can be fully mixed and contacted. The desulfurized flue gas is demisted by the wet electrostatic precipitator in the tower, and then enters the heat exchanger for temperature rise. After reaching the emission standard, it is discharged into the atmosphere through the chimney. After desulfurization, the washing solution containing ammonium sulfate is crystallized to form by-product ammonium sulfate

(4) NKK ammonia process

nkk ammonia process is a process developed by Japan steel pipe company. The absorption tower has certain characteristics and is divided into three sections. From bottom to top, the lower section is pre washing, dedusting and cooling. In this section, there is no absorbent added. The middle section is the first absorption section from which absorbent is added. The upper section is used as the second absorption section, but no absorbent is added, and only craft water is processed. The flue gas after absorption treatment is heated by the heater and then sent to the chimney. Ammonium sulfite oxidation is carried out in a separate oxidation reactor. The required oxygen is supplemented by compressed air, and the oxidation residual gas is discharged to the absorption tower

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