Light burning magnesium ball tower -- a desulphurization method suitable for new and old boilers
Technical characteristics of magnesium oxide desulfurization process
1. Mature technology
Light fired magnesium ball magnesium oxide desulphurization technology is a kind of desulfurization technology with maturity second only to calcium method. Magnesium oxide desulphurization technology has been widely applied around the world. Light fired magnesium powder has been applied in more than 100 projects in Japan, 95% of power plants in Taiwan use magnesium oxide method, and it has been applied in the United States, Germany and other places. And it has applied the results in some parts of our country at present.
2. Sufficient source of raw materials
The reserves of magnesia in China are very considerable. At present, the proven reserves of magnesia are about 16 billion tons, accounting for about 80% of the world. Its resources mainly in Liaoning, magnesium oxide can be used as desulfurizer in power plant desulfurization system.
3, high desulfurization efficiency
In terms of chemical activity, magnesium oxide is much larger than calcium based desulfurizer, and because the molecular weight of magnesium oxide is smaller than calcium carbonate and calcium oxide. The desulphurization efficiency of magnesia is higher than that of calcium process under other conditions being equal. Under normal circumstances, the desulfurization efficiency of magnesia can reach 95~98%, but the desulfurization efficiency of limestone/gypsum method only reaches 90~95%.
4. Less investment cost
Since magnesium oxide has its unique advantages as a desulphurization system, the structure design of the absorption tower, the size of the circulating slurry, the overall scale of the system, and the power of the equipment can be reduced accordingly. In this way, the investment cost of the whole desulphurization system can be reduced by more than 20%.
5. Low operating cost
The main factors that determine the operating cost of desulfurization system are the consumption cost of desulfurizer and the consumption cost of water, electricity and steam. The price of magnesium oxide is higher than that of calcium oxide, but the amount of magnesium oxide to remove the same SO2 is 40% of calcium carbonate; The liquid-gas ratio is a very important factor in the power consumption of water, electricity and steam, which is directly related to the desulfurization efficiency of the whole system and the operating cost of the system. For the limestone gypsum system, the liquid-gas ratio is generally above 15L/m3, and 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 by-products of magnesium oxide process can offset a large part of the cost.
6, reliable operation
Compared with calcium method, the biggest advantage of magnesium method is that the system will not occur scale blockage problem of equipment, which can ensure the safe and effective operation of the whole desulfurization system. At the same time, the PH value of magnesium method is controlled between 6.0 and 6.5, and the corrosion problem of equipment can be solved to a certain extent. In general, the safety performance of magnesium desulphurization in practical projects has a very strong guarantee.
7. High comprehensive benefit
As the reaction products of magnesium desulphurization are magnesium sulfite and magnesium sulfate, the comprehensive utilization value is very high. On the one hand, we can carry out forced oxidation to produce magnesium sulfate, and then concentrate and purify to produce magnesium sulfate heptahydrate for sale. On the other hand, we can also directly calcination to produce sulfur dioxide gas with higher purity to produce sulfuric acid.
8, byproduct utilization prospects are broad
We know that sulfuric acid is known as the "mother of the chemical industry", sulfur dioxide is the raw material to produce sulfuric acid. China is a relatively deficient country in sulfur resources. The annual import volume of sulfur exceeds 5 million tons, equivalent to 7.5 million tons of sulfur dioxide. In addition, magnesium sulfate is widely used in food, chemical industry, medicine, agriculture and other aspects, and the market demand is also relatively large. Magnesium desulphurization makes full use of existing resources and promotes the development of circular economy.
9. No secondary pollution
In the common wet desulphurization process, the problem of secondary pollution is unavoidable. For the magnesium oxide desulfurization technology, the follow-up treatment is relatively perfect, SO2 regeneration, to solve the problem of secondary pollution.
The desulfurization mechanism of magnesium oxide is similar to that of calcium oxide. Both of them are alkaline oxide reacting with water to form hydroxide, and then conducting acid-base neutralization reaction with sulfur dioxide dissolved in water to form sulfite solution. Magnesium sulfite and magnesium sulfate generated by the reaction of magnesium oxide are reused after recycling SO2 or forced oxidation to convert all of them into sulfate to make magnesium sulfate heptahydrate. The main chemical reactions in the process of desulfurization are MgO+H2O=Mg(OH)2Mg(OH)2+SO2=MgSO3+H2OMgSO3+H2O+SO2=Mg(HSO3)2MgSO3+1/2O2=MgSO4 The main reactions in the regeneration stage of magnesium oxide are MgSO3→MgO+SO2M gSO4→MgO+SO3Mg(HSO3)2→MgO+H2O+2SO2SO2+1/2O2→SO3SO3+H2O→H2SO4: MgSO3+1/2O2→MgSO4MgSO4+7H2O→MgSO4·7 when forced oxidation of by-products to MgSO4·7H2O is carried out H2O