Through the burning high sulphur coal fired power plant for wet flue gas desulfurization system, comparison and Analysis on single absorption tower and set the Twin Towers series, while burning high sulfur coal, and high desulfurization efficiency, the Twin Towers series can greatly reduce power consumption of desulfurization process, and a brief introduction of absorption tower series used in practical engineering application the feasibility analysis and the successful application and operation of Engineering examples. The absorption tower in coal series of flue gas desulfurization in such application
1 Introduction
The sulfur content of coal in China varies from 0.1% to 10%. Generally speaking, China is a country with more sulfur coal reserves, according to statistics, there are about 30% of coal sulfur content in China's coal resources in more than 2%, especially in the southwestern region of some coal sulfur content of up to 10%. At present, our country is about 1/6 in coal mining, mining in high sulfur coal, low sulfur type is large, some high-quality low sulfur coal coal face such as depletion of resources: the famous Datong coalfield, high-quality low sulfur coal can only be mined for 15 years. Therefore, we have to face with the passage of time, more and more, the use of high sulfur coal.
SO2 is one of the main pollutants causing air pollution, so it is urgent to control the SO2 in industrial flue gas. China's 2011 national sulfur dioxide emissions up to 22 million 179 thousand tons, has become the world's largest SO2 emissions. The resulting economic losses of more than 500 billion yuan.
China's annual emissions into the atmosphere of 87% of SO2 derived from the direct combustion of coal. About half of which comes from the thermal power plant, with the acceleration of China's industrialization process, SO2 emissions are increasing. In order to reduce the total amount of SO2 discharged into the atmosphere, GB13223-2011 "air pollutant emission standards for thermal power plants" has been implemented, the new power plant SO2 emission standards are more stringent, requiring emissions is not greater than 100mg/Nm3.
From above. The future development trend of Chinese desulfurization industry, with burning coal sulfur content is more and more high, thermal power plant air pollutant emission standards will be more and more strict, so, will require the desulfurization efficiency of flue gas desulfurization system becomes more and more high.
2 current status of desulfurization system in China
The wet flue gas desulfurization technology and dry circulating fluidized bed technology, as well as semi dry flue gas desulfurization technology. According to statistics, wet flue gas desulfurization technology in the world has been installed and stable operation of power plant flue gas desulfurization installed capacity of 85, especially in Japan accounted for 98%, the United States accounted for 92%. Large and medium sized power plants with 200 thousand KW generating units in China, wet desulfurization also accounts for more than 90% of the total installed capacity of desulfurization, desulfurization of large units of more than 600 thousand kilowatts, and so far all wet FGD technology.
In the removal of SO2 in flue gas desulfurization system at the same time, also need to consume much energy, such as water, gas, electricity, limestone, coal sulfur content is higher, the desulfurization efficiency need is also higher, while the energy consumption is high, the desulfurization efficiency of wet at around 95%, is widely used in single absorption tower desulfurization process using limestone gypsum wet desulfurization process in the main.
Wet desulfurization process in all desulfurization process, when the system is running around the highest power consumption, usually generating capacity of 0.6 ~ 1%, coal unit can be higher than 3%, with the sulfur content of coal is increased and increased the desulfurization efficiency, desulfurization system power consumption will also increase, in the wet FGD system in large power equipment main: desulfurization booster fan and the absorber slurry circulating pump, ball mill, lime stone gypsum dehydration vacuum pump and oxidation fan, the desulphurization booster fan, absorption tower slurry circulating pump about power consumption accounted for the power consumption of the desulfurization system 60%.
3 single tower and power consumption performance comparison series of absorption tower
Wet FGD system set up a single absorption tower and two absorption tower series operation, in the desulfurization system, the main difference is that the absorption tower set is not the same, so increase desulfurization booster fan power consumption of different equipment containing only the absorber slurry circulating pump and overcome the smoke caused by pressure loss caused by the absorption tower the different power consumption involved, with a single 600MW unit as an example, the flue gas composition conditions are as follows:
Flue gas volume: 2200000Nm3/h (standard state, wet basis, actual O2)
Flue gas temperature: 125
Inlet flue gas composition: H2O:7.5Vol% (standard state, wet basis, actual O2)
O2:5.55Vol% (standard state, wet basis, actual O2)
Inlet flue gas SO2 content: 10000Nm3/h (standard state, dry base, 6Vol%O2), equivalent to 4.2% of the sulfur content of coal.
Meet environmental emissions, desulfurization efficiency of not less than 99%.
According to a single set of absorption tower, absorption tower desulfurization efficiency of not less than 99%, if the 2 absorption tower series configuration, each of the desulfurization efficiency of the absorption tower with not less than 90%, the overall efficiency is 90% (190%) * 90% = 99%, the desulfurization efficiency is the same.
3.1 set according to a single absorber
The absorption tower desulfurization efficiency is related to many factors, but the main factors are the size of the amount of slurry circulation, circulation ratio is slurry flow and gas flow, commonly known as the ratio of liquid to gas, liquid gas ratio is higher, the desulfurization efficiency is high, the following table is based on the absorption tower developed by MHI (the liquid column tower) software to calculate the desulfurization performance, under the same conditions, slurry circulation volume (m3/h) curve with the desulfurization efficiency:
Through the upper curve, it was found that the desulfurization efficiency increased with the increase of the slurry circulation, but with the increasing proportion of the slurry circulation, the proportion of desulfurization efficiency was getting smaller and smaller. At the same time, the amount of slurry circulation increases