Lime powder is an important desulfurizer for power plant desulfurization because it can effectively remove the sulfur dioxide given out by coal burning and make the given out gases meet national standard. But power plant desulfurization has finesses requirement to lime power and grinding machine can be chosen only after lime powder fineness is determined.

How dose lime powder desulfurize for tail gas? Crushed lime powder are injected to best reactive temperature area by compressed air to make full contact and good reactive time between lime powder and smoke. The main component of lime powder is calcium carbonate (CaCO₃),which will break down calcium oxide (Cao) and carbon dioxide(CO₂)under high temperature and then calcium oxide reacts with sulfur dioxide with oxygen to form calcium sulfate (CaSO₄).Calcium sulfate is the main component of chemical gypsum which can be used in following production. The desulfurization principle is realized through every elements’ chemical property in nature and the specific chemical equation is as followed:

CaCO₃→CaO+CO_{2 、}CaO+SO₂+1/2O₂→CaSO₄

Seeing from the chemical equation, we can see that limestone realizes desulfurization also through breaking down calcium oxide under high temperature. And desulfurization by calcium oxide has better result than by calcium carbonate so power plant has high requirement for desulfurization will chose calcium oxide rather than alcium carbonate. But both of them can be used for desulfurization. And calcium carbonate becoming to calcium oxide needs help of high temperature which needs to build up a calcining kiln and increases cost. So most power plant chose crushed lime powder. And generally, calcium carbonate is used for in-furnace desulphurization and calcium oxide is for in-stack desulphurization.

From the above working principle for power plant desulfurization we can know that the reaction speed is related to element property as well as external factors such as temperature and contacting area, etc.

The injected temperature can be controlled but how to increase the contacting area? It’s actually not difficult, as long as to increase fineness of desulfurizer. Therefore, selected grinding machine has to be able to produce fine and uniform powders for better chemical reaction. And the finer the lime powder is, the better the desulfurization result is. If only considering fineness, superfine mill, three-ring medium speed mill are the properest. But grinding powder needs energy consumption and fineness is proportional to energy consumption. So superfine mill is not the properest choice for power plant

Experiments show that desulfurization by lime power of 325 mesh can completely meet national air quality standards. If high-purity lime powder with good quality and appearance, 250 mesh is enough to be used for power plant desulfurization. And the fineness of desulfurization depends the choice of grinding machine. Raymond mill, trapezoidal mill, high-pressure suspension roller mill, European mill, vertical mill, etc. all are suitable for desulfurization, and among them, European mill and suspension mill are commonly used in power plant because both of them have high capacity, high efficiency, uniform fineness and high grade, especially the European mill which is widely used for desulfurization.

Power plants in China usually buy desulfurizer directly from abroad, some make desulfurizer by limestone themselves. General Mining Machinery experts want to tell you that though you won’t have to buy grinding machine, you must be careful of lime powder’s purity and fineness when buying from abroad and that if you want make desulfurizer yourself, your key problem is to select proper grinding machine so that you need to find a long-term cooperating machinery factory. General Mining Machinery has undertaken grinding machine over ten years and accumulated more than 3,000 clients. And we would like to share our experience with you, so if you have any machinery needs or technical problems, please feel free to call us: 0371-67828877, 13733166918.