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Technical characteristics of desulfurization process of magnesia light burning powder
1. Technological maturity
Magnesium oxide desulfurization technology is a kind of desulfurization technology whose maturity is only inferior to calcium method. Magnesium oxide desulfurization technology has a lot of application achievements all over the world. Among them, more than 100 projects have been applied in Japan, 95% of Taiwan's power plants are using magnesium oxide method, and it has been applied in the United States, Germany and other places. At present, Magnesium oxide desulfurization technology has been applied in some parts of China.
Reburnt magnesia products
2. Adequate sources of raw materials
Magnesium oxide reserves in China are considerable. At present, the proven reserves of magnesium oxide are about 16 billion tons, accounting for about 80% of the world. Its resources are mainly in Liaoning Province. Magnesium oxide can be used as desulfurizer in power plant desulfurization system.
3. High desulfurization efficiency
Magnesium oxide is much more active than calcium-based desulfurizer in chemical reaction, and its molecular weight is smaller than that of calcium carbonate and calcium oxide. Therefore, the desulfurization efficiency of magnesium oxide is higher than that of calcium method under the same other conditions. Generally, the desulfurization efficiency of magnesium oxide can reach 95-98%, while the desulfurization efficiency of limestone/gypsum method can only reach 90-95%.
4. Less investment costs
Magnesium oxide as desulfurization has its own unique advantages, so the structure design of absorption tower, the size of circulating slurry, the overall scale of the system and the power of the equipment can be relatively small, so that the investment cost of the whole desulfurization system can be reduced by more than 20%.
5. Low operating costs
The main factors determining the operation cost of desulfurization system are the consumption cost of desulfurizer and water, electricity and steam. The price of magnesium oxide is higher than that of calcium oxide, but the consumption of removing the same SO2 magnesium oxide is 40% of calcium carbonate. The liquid-gas ratio is a very important factor in power consumption, such as water, electricity and steam, which directly affects the desulfurization efficiency of the whole system and the operation cost of the system. For the limestone gypsum system, the liquid-gas ratio is generally above 15L/m3, while the magnesium oxide is below 5L/m3, so the magnesium oxide desulfurization process can save a large part of the cost. At the same time, the sale of magnesium oxide by-products can offset a large part of the cost.
6. Reliable operation
The greatest advantage of magnesium desulfurization over calcium desulfurization is that the system will not cause fouling and blockage of equipment, and can ensure the safe and effective operation of the whole desulfurization system. At the same time, the PH value of magnesium desulfurization is controlled between 6.0 and 6.5. Under this condition, the corrosion problem of equipment has also been solved to a certain extent. Generally speaking, the safety performance of magnesium desulfurization in practical projects has a very strong guarantee.
7. High Comprehensive Benefit
Because the reaction products of magnesium desulfurization are magnesium sulfite and magnesium sulfate, the comprehensive utilization value is very high. On the one hand, all magnesium sulfate can be produced by forced oxidation, and then concentrated and purified to produce magnesium sulfate heptahydrate for sale. On the other hand, sulfur dioxide gas with high purity can be directly calcined to produce sulfuric acid.
8. Broad prospects for the utilization of by-products
We know that sulfuric acid is known as the "mother of the chemical industry", and sulfur dioxide is the raw material for the production of sulfuric acid. China is a country with relatively scarce sulphur resources. The annual import of sulphur exceeds 5 million tons, equivalent to 7.5 million tons of sulphur dioxide. In addition, magnesium sulfate is widely used in food, chemical industry, medicine, agriculture and many other fields, and the market demand is also relatively large. Magnesium desulfurization makes full use of existing resources and promotes the development of circular economy.
9. No secondary pollution
In the common wet desulfurization process, secondary pollution inevitably exists. For magnesium oxide desulfurization technology, the follow-up treatment is more perfect, SO2 is regenerated to solve the problem of secondary pollution.
The reaction mechanism of magnesium oxide desulfurization is similar to that of calcium oxide desulfurization. Both of them are alkaline oxides reacting with water to form hydroxides, and then reacting with sulfite solution formed by sulfur dioxide dissolving in water to neutralize acid and alkali. Magnesium sulfite and magnesium sulfate produced by magnesium oxide reaction are reused or converted into forced oxidation after recovery of SO2. Magnesium sulfate heptahydrate is prepared from sulfate. The main chemical reactions occurring during desulfurization are MgO+H2O=Mg(OH)2Mg(OH)2Mg(OH)2Mg(OH)2+SO2=MgSO3+MgSO3+H2O+SO2=Mg(HSO3)2MgSO3+1/2O2=MgSO3+MgSO3+1/1/2O2=MgSO4 magnesium oxide during the regeneration stage of MgSO4 magnesium oxide. The main reactions occurring during the regeneration stage of MgSO3_MgSO3_MgO+SO2 Mg Mg Mg MgO+SO2 MgSO4 MgO+SO3MgMgMgMgO+SO3MgMgMgMgMgMgMgO(HSO(HSO)2)2 MgO+H2OMgSO3+1/2O2_MgSO4 when the by-product is forcibly oxidized to MgSO4.7H2O for sale MgSO4+7H2O_MgSO4.7H2O
Magnesium oxide desulfurization technology is a promising desulfurization technology in the wet desulfurization process which has been commercialized. The process is mature, less investment, simple structure, good safety performance, and can reduce secondary pollution, recycle desulfurizer, reduce the cost of desulfurization, and bring certain economic benefits. Compared with calcium desulfurization, it avoids a series of problems existing in simple wet process, such as pipeline blockage, low flue temperature, flue gas carrying water and secondary water pollution, etc. At the same time, compared with the more complete limestone/gypsum method, it occupies a small area, has a low operating cost, greatly reduces the investment, and greatly improves the comprehensive economic benefits.