Wet desulfurization of Pittsburgh No. 8 coal and Illinois No. 6 coal were conducted with sodium hypochlorite in the laboratory. Pittsburgh No. 8 coal was leached. Adv Biochem Eng Biotechnol. ; doi: /10__ The microbial desulfurization of coal. Rossi G(1). Author information. The major coal desulphurization technologies prior to combustion are physical coal cleaning, chemical and biological methods. Each has some technical and.
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Because of scale buildup, plugging, or erosion, which affect FGD dependability and absorber efficiency, the trend is to use simple scrubbers such as spray towers instead of more complicated ones. The configuration of the tower may be vertical or horizontal, and flue gas can flow cocurrently, countercurrently, or crosscurrently with desulphurization of coal to the liquid.
The microbial desulfurization of coal.
The chief drawback of spray towers is that they require a higher liquid-to-gas ratio requirement for equivalent SO 2 removal than other absorber designs. FGD scrubbers desulphurization of coal a scaling wastewater that requires treatment to meet discharge regulations.
The converging section accelerates the gas stream to high velocity. When the liquid stream is injected at the throat, which is the point of maximum velocity, the turbulence desulphurization of coal by the high gas velocity atomizes the liquid into small droplets, which creates the surface area necessary for mass transfer to take place.
The higher the pressure drop in the venturi, the smaller the droplets and the higher the surface area.
The penalty is in power consumption.
For simultaneous removal of SO 2 and fly ash, venturi scrubbers can be used. In fact, many of the industrial sodium-based throwaway systems are venturi scrubbers originally designed to remove particulate matter.
The microbial desulfurization of coal.
These units were slightly modified to inject a sodium-based scrubbing liquor. Although removal of both particles and SO 2 in one vessel can be economic, the problems of high pressure drops and finding a desulphurization of coal medium to remove heavy loadings of fly ash must be considered.
However, in cases where the particle concentration is low, such as from oil-fired units, it can be more effective to remove particulate and SO 2 simultaneously. desulphurization of coal
Packed bed scrubbers[ edit ] A packed scrubber consists of a tower with packing material inside. This packing desulphurization of coal can be in the shape of saddles, rings, or some highly specialized shapes designed to maximize the contact area between the desulphurization of coal gas and liquid.
Packed towers typically operate at much lower pressure drops than venturi scrubbers and are therefore cheaper to operate.
They also typically offer higher SO 2 removal efficiency. The drawback is that they have a greater tendency to plug up if particles are present in excess in the exhaust air stream.
It consists of a tower with spray nozzles, which generate the droplets for surface contact. Spray towers are typically used when desulphurization of coal a slurry see below.
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The high speed of a venturi would cause erosion problems, while a packed tower would plug up if it tried to circulate a slurry. Counter-current packed towers are infrequently used because they have a tendency to become plugged by collected particles or to scale when lime or limestone scrubbing slurries are used.
Scrubbing reagent[ edit ] As explained above, alkaline sorbents are used for scrubbing flue gases desulphurization of coal remove SO2.
Depending on the application, the two most important are lime and sodium hydroxide also known as caustic soda. Lime is typically used on large coal- or desulphurization of coal boilers as found in power plants, as it is very much less expensive than caustic soda.
The problem is that it results in a slurry being circulated through the scrubber instead of a solution. This makes it harder on the equipment.
A spray tower is typically used for this application.
Flue-gas desulfurization - Wikipedia
The use of lime results in a slurry of calcium sulfite CaSO3 that must be disposed of. Caustic soda is limited to smaller combustion units because it is more expensive than lime, but it has desulphurization of coal advantage that it forms a solution rather than a slurry. This makes it easier to operate.