Semi-dry desulfurization


2022-04-21 10:50

Process principle:

The semi-dry desulfurization process means that the desulfurizer is added in a wet state, and the moisture in the slurry is evaporated by the sensible heat of the flue gas. During the drying process, the desulfurizer reacts with the sulfur dioxide in the flue gas to form a dry powder product. In order to improve the desulfurization efficiency, lime powder is usually used as a desulfurizing agent. If the bag filter is used together, the desulfurization efficiency can be improved by 10% to 15%.

Craft classification:

Humidified ash cyclic desulfurization process, also known as NID technology. It is to mix the slaked lime powder and the circulating ash collected by the dust collector in the mixing humidifier, add water to humidify to a moisture content of 5%, and then introduce it into the flue reactor for desulfurization reaction. The circulating ash containing 5% moisture is relatively Good fluidity, eliminating the need for complicated pulping systems and overcoming the problem of sticking walls during spraying. 

Rotary spray drying process, also known as LSD method. Lime powder is used as the desulfurizing agent, which is digested with water and made into slaked lime milk, which is pumped into the atomization device in the absorption tower, and atomized into fine droplets by the rotating spray wheel. During the process of mixing and contacting with the flue gas, It reacts with sulfur dioxide in the flue gas to form calcium sulfite, most of the sulfur dioxide in the flue gas is removed, the droplets are dried, and the flue gas temperature drops. The desulfurization reaction product and the unused desulfurizer are partially carried out of the flue gas into the dust collector in the form of dry particles and collected, and partially separated from the flue gas by centrifugal action, and discharged from the bottom of the absorption tower. In order to improve the utilization rate of the desulfurizer and reduce the ratio of calcium to sulfur, the dry powder and fly ash collected by the dust collector are generally added to the pulping system for recycling. 

Gas suspension absorption process, referred to as GSA method. The boiler flue gas enters from the bottom of the reactor and mixes with the lime slurry injected by the nozzle when passing through the throat. In the reactor, the lime slurry reacts with acid gases such as sulfur dioxide in the flue gas during the drying process, the flue gas discharged from the top of the reactor enters the cyclone, and most of the desulfurized ash taken out is captured and then enters the reactor again for circulation When used, a small part enters the dust collector with the flue gas.

  System Features:  

The process is simple, the structure is compact, the project investment is low, the desulfurization operation and maintenance cost is low, and the project occupies a small site, which can bring maximum benefits to users. Scope of application: Medium and low sulfur coal circulating fluidized bed boiler