DE3642178A1 - Process and apparatus for dry SO2 and NOx separation downstream of fired boiler plants - Google Patents

Abstract

It known to separate off SO2 and NOx by flue gas scrubbing systems or dry additive systems and to use catalysts downstream of the SO2 separation in order to reduce the NOx load. It is further known to use coke from bituminous coal or brown coal to separate off NOx. In order to create a reliable, economical, easy to operate plant technology with the known reducing agents bituminous coal coke and/or brown coal coke, according to the invention it is proposed that SO2 separation is arranged downstream of the actual combustion boiler (9) and downstream of this is arranged a packed bed prefilter (5) for the SO2 separation, which prefilter is preferably charged with brown coal coke and downstream of the packed bed prefilter, a component (4), preferably NH3, necessary for the catalytic reduction of NOx is injected into the gas before this is fed to a packed bed filter (6) and passes from this into a further packed bed filter (7), which latter is charged with coke already once laden with SO2 in the packed bed prefilter (5) and the packed bed filter (7) represents a prefilter for the dust filter (8). <IMAGE>

Description

It is known to separate SO ₂ and NO _x using flue gas scrubbing plants or dry additive plants and to use catalysts behind the SO ₂ separation to reduce the NO _x pollution.

It is also known to use coke from hard coal or brown coal to separate NO _x .

In order to produce a reliable, economical, easy-to-operate plant technology with the known reducing agents stone and / or brown coal coke, a method is proposed according to the invention which is economically justifiable for SO ₂ and NO _x separation.

In the drawing, the implementation according to the invention is shown -
with ( 1 ) the raw gas coming from the boiler
with ( 2 ) an unused brown and / or hard coal coke, which is introduced into the bulk bed prefilter ( 5 ) via lines ( 3 ) - in the prefilter, the SO ₂ contained in the raw gas is separated as much as possible, at ( 4 ) NH ₃ atomized for the bulk filter ( 6 ) for NO _x separation and the coke absorbent used in the bulk prefilter ( 5 ) is pneumatically fed to the bulk filter ( 7 ) via a pressure transmitter ( 4 a) and in this filter for the remaining separation of SO ₂ and NO _x and cracked slippage of reducing gases such as NH ₃ .

The coke used from the bulk filter ( 6 ) and bulk filter ( 7 ) and from the dust filter ( 8 ) via pneumatic conveyors ( 4 b , 4 c and 4 d) pneumatically fed to the boiler.

This simple bulk filter technology and the connection with pneumatic pressure conveyor systems that work intermittently according to the used reaction coke ensures an environmentally friendly technology that completely removes the residue product from the catalyst area for the separation of SO ₂ and NO _x and reducing gas, such as NH ₃ , into the combustion chamber conveyed to the boiler, here according to the invention the boiler must be provided with an SO ₂ separator in order to extract from the coke - e.g. B. Lignite coke - releasing residual amounts of SO ₂ in the boiler integrated or downstream SO ₂ separation system and reducing by-products such. B. burn ammonium compounds in the boiler and thus ensure environmentally friendly SO ₂ and NO _x separation without residue product.

Claims (2)

1. Method and device for wet and dry SO ₂ - and NO _x separators behind combustion plants, characterized in that behind the actual combustion boiler ( 9 ) a wet or semi-dry SO ₂ separation is arranged, which has the highest possible SO ₂ separation rate of more than 80% and behind this SO ₂ separation the cleaned raw gas ( 1 ) is fed to a bulk prefilter for the SO ₂ separation ( 5 ), which is operated via pneumatic, preferably intermittently operating pressure transmitters with ( 3 ) with coke, preferably brown coal coke, is filled and behind the bulk prefilter ( 5 ) a component required for the catalytic reduction of NO _x - preferably NH ₃ - is injected at ( 4 ) - and that is largely freed of SO ₂ , but still NO _x- loaded gas is fed to the bulk filter ( 6 ) - the gas flowing out of the bulk filter ( 6 ) is fed to the bulk filter ( 7 ) and this with the bulk pre-filter ( 5 ) feed the coke filter ( 7 ) to the coke filter ( 7 ) with coke loaded with SO ₂ via a pressure transmitter ( 4 a) at ( 3 b), the bulk filter ( 7 ) being a pre-filter of the rod filter ( 8 ) and the dust filter ( 8 ) the torn, fine dust particles of the bulk filter ( 7 ) with the chemisorbing effect to absorb residual SO ₂ and residual NO _x together with the slip gas ( 4 ) - z. B. NH ₃ - and finally, with a subsequent reaction on the dust filter system ( 8 ) to achieve the greatest possible separation of SO ₂ , NO _x and slip gas ( 4 ) and pneumatically - depending on the clean gas load - controlled the pressure transmitters of the series 4 a to 4 d Feed the total dust to the boiler firing and the residual SO ₂ quantities accumulated in the dust filter ( 8 ) are released in the dust in the boiler firing and are separated in the SO _{2 system} downstream of the boiler, ammonium salts or NH still present in the capillaries at the same time ₃ traces burned in the boiler firing and thus the separation and recycling of residues is guaranteed to be environmentally friendly. 2. The method according to claim 1, characterized in that the bulk filter ( 7 ) at low NO _x pollution in the bulk filter ( 6 ) layers in favor of charging chemisorption filter, consisting of the coke dust originating on the bulkhead pre-filter ( 5 ) and the dust filter fabric as Precoat layer is superimposed, so that the coarse particles are immediately fed to the pneumatic conveyor ( 4 d) via the pre-separator of the dust filter ( 8 ) and the precoated dust filter with the pre-reacted coke ( 5 ) the residual separation of SO ₂ , NO _x and slip gas ( 4 ), e.g. B. NH ₃ guarantee.