Flue gas desulfurization technology can generally be divided into three categories: dry method, semi-dry method and wet method. Dry method includes: SDS, CFB, SDA, NID and dense coherent method, etc. Wet flue gas desulfurization technology is relatively mature, including lime gypsum method, sodium alkali method, magnesium method, zinc oxide method and so on. Circulating fluidized bed semi dry desulfurization technology is a typical representative of semi dry desulfurization technology. It is a method with the largest single tower treatment capacity and the best desulfurization comprehensive benefit in the current dry desulfurization technology. It can achieve high desulfurization efficiency at a lower Ca / S.
Compared with other flue gas desulfurization processes, this process has significant advantages such as less investment, low operating costs, small footprint, less desulfurization by-products, no waste water discharge, reliable operation, simple process, easy maintenance, and no secondary pollution. Its desulfurization efficiency can reach 85-99% according to the actual requirements of the owner.
Compared with wet flue gas desulfurization technology, semi-dry flue gas desulfurization cost benefit is better
The process of flue gas circulating fluidized bed semi-dry high-efficiency desulfurization system is mainly used for boiler flue gas desulfurization in power stations, iron and steel metallurgy, petrochemical, building materials, etc. The flue gas processing capacity of a single tower can be applied to 6MW to 300MW units.
The current wet desulfurization technology used in FGD plant has the following shortcomings.
- It can not eliminate sulfuric acid mist aerosol particles formed by SO3.
- Wet desulfurization wastewater is difficult to treat, large investment, large area, and high operating cost.
- The elemental mercury in the flue gas cannot be removed.
In contrast, semi-dry desulfurization can achieve zero waste water desulfurization while reaching the national ultra-low emission target. The removal rate of PM2.5 is ≥95%, the emission of mercury is ≤3ug/Nm3, and the comprehensive removal rate of heavy metals is ≥90%，S03 desulfurization rate ≥ 95%, S03 emission ≤ 5 mg/Nm3.
On the basis of summarizing engineering experience, Ruichang developed a Circulating Fluidized Bed Flue Gas Desulfurization Process suitable for current environmental protection requirements.
Cost Benefit Comparison between CFB-FGD System and Limestone Gypsum Wet FGD System
We compared the investment amount, water consumption, power consumption, floor area and maintenance cost.
|Item||CFB semi-dry desulfurization method||Limestone-gypsum wet method|
Through comparison, it can be seen that the cost of the CFB semi-dry desulfurization method in five dimensions is significantly less than that of the limestone-gypsum wet method. CFB-FGD technology, the circulating fluidized bed semi-dry desulfurization technology, uses dry slaked lime powder Ca(OH)2 as the absorbent, and through multiple recycling of the absorbent, the absorbent and flue gas are added in the desulfurization tower Therefore, the utilization rate of the absorbent is greatly improved, and the purpose of high-efficiency desulfurization is finally achieved. The key point of the fgd process is that the desulfurization reaction is carried out in a semi-wet state, and the desulfurization product is processed in a dry state, which has the advantages of fast wet desulfurization reaction speed and high desulfurization efficiency, and the dry desulfurization process has no waste water. The advantages of liquid discharge and the ability to process desulfurization products in a dry state.
Technical Advantages of Main Equipment in the FGD System
Desulfurization Fluidized Bed Reacting Tower
- The gas-solid mass transfer rate is fast, making the reaction more complete.
- Low requirement on particle size of desulfurizer.
- Only one feeding point.
- Large load regulation ratio and fast regulation speed.
- The desulfurizer can be recycled and has a high utilization rate.
- The section has high wind speed, the bed is long and thin, and it occupies a small area.
Bag House De-duster
- High dust removal efficiency, emission <20mg/Nm3.
- Simple structure, modular assembly, light equipment.
- Strong adaptability, can capture dust with different properties and smaller particle size.
- Flexible use, large adjustment ratio, the amount of flue gas can be processed from 1000 cubic meters/h to 1 million cubic meters/h.