Method for treatment of smoke gas from sulfur dioxide

FIELD: heat technology.

SUBSTANCE: invention relates to technology for treatment of smoke gases from sulfur dioxide. Method for treatment of smoke gases from sulfur dioxide involves passing smoke gases through countercurrent scrubber with absorption liquid based on ammonia aqueous solution for preparing ammonium sulfite followed by oxidation of ammonium sulfite to ammonium sulfate. Then one part of absorption solution removing after oxidation is mixed with fresh ammonium aqueous solution and fed to treatment of smoke gases and another part is fed to utilization. Oxidation is carried out with smoke gases oxygen in indicated scrubber in addition initiating agent for oxidation to absorption liquid as azocompounds. Invention provides simplifying the process and to reduce time for accumulation of ammonium sulfite by 1.8-2.0-fold.

EFFECT: improved method for treatment.

 

The invention relates to heat engineering, in particular to a technology for purifying flue gases from sulfur dioxide.

The known method (Germany application No. 19731062, B 01 53/77 D, 1999 - prototype) removal of sulfur dioxide from flue gases, based on the use of aqueous ammonia solution (absorption solution). Flue gases containing sulfur dioxide, is passed through a counter-current scrubber with an aqueous solution of ammonia with obtaining ammonium sulfite. Carry out the oxidation of ammonium sulfite to ammonium sulfate in the apparatus for oxidation, feeding it with compressed air. Part of the exhaust after the oxidation of the absorption solution is mixed with fresh water ammonia solution and sent for purification of flue gases, and the other part of the exhaust after oxidation absorption solution for recycling. This mode provides optimum pH 5-6,5, thereby increasing the degree of purification of sulfur dioxide. The disadvantage of this method is the necessity of using the device for oxidation, as well as additional equipment (pumps, pipelines) for filing in this apparatus compressed air.

Achieved by the invention is to simplify the method.

This is ensured by the fact that in the method of cleaning flue gases from sulfur dioxide, which consists in the fact that the flue gases are passed through a counter-current scrubber with the absolute is blonay liquid-based aqueous ammonia to obtain ammonium sulfite, carry out the oxidation of ammonium sulfite to ammonium sulfate, then one part of the exhaust after the oxidation of the absorption solution is mixed with fresh water ammonia solution and sent for purification of flue gases, and the other part - for recycling, oxidation according to the invention carried out by the oxygen of the flue gases in the specified scrubber, with the addition in the absorption liquid initiator of oxidation in the form of azo compounds.

Azo compounds are compounds containing one or more isogroup, which consist of two nitrogen atoms connected by a double bond (-N=N-). Isograph can occur between the various, mainly aromatic groups. This technical solution of the compounds can contain along with isopropol aryl (AG), alkyl (Alk) and phenyl (R) group. Such compounds break down into radicals, and therefore they are the initiators of radical oxidation reactions. When the decomposition of azo compounds leads to the formation of radicals by the scheme:

Ar-N=N-R→ Ar* +N+R*

Where N is nitrogen,

AG - aryl group,

R is a phenyl group,

AG* , R* radical

The formed radicals initiate in turn, the formation of ion-radicals SO3*, SO4*, SO5*leading chain of oxidation of ammonium sulfite. Presence mandatory UN paid the tank additives allows cleaning of flue gases from sulfur dioxide without the use of the apparatus for oxidation, feed him in the compressed air and the necessary additional equipment.

The method according to the invention can be illustrated by the following example.

Flue gases from coal-fired boiler with a temperature no higher than 120° in quantities of 1000 nm3/h, with a sulfur concentration of 0.15% by serves for cleaning the bottom of the scrubber. The scrubber is operating in counterflow mode of interaction between the gas and the liquid. Irrigation scrubber is carried out in a closed loop solution containing uzasadnienie in the number 0,0015% wt. content in the solution of the sulfite ion. When the accumulation in the solution of ammonium sulfate 300-350 g/l part of it is collected and sent for recycling. When the flue gas cleaning fluids without additives initiator oxidation accumulation of ammonium sulfate to a concentration of 300 g/l is within 25-30 hours. With the introduction of the solution of the azo compounds accumulation time of ammonium sulfate is reduced accordingly 1.8-2.0 times. In this mode does not require the use of the device for oxidation, as well as additional equipment (pumps, pipelines) for filing in this apparatus compressed air. And complied with optimum pH of the solution to obtain a high degree of purification from sulfur dioxide in the flue gases.

The method of cleaning flue gases from sulfur dioxide, consisting of t is m, that flue gases are passed through a counter-current scrubber with an absorbing liquid-based aqueous ammonia to obtain ammonium sulfite, carry out the oxidation of ammonium sulfite to ammonium sulfate, then one part of the exhaust after the oxidation of the absorption solution is mixed with fresh water ammonia solution and sent for cleaning of the flue gases and the other for recycling, characterized in that the oxidation is conducted with oxygen flue gases in the specified scrubber, with the addition in the absorption liquid initiator of oxidation in the form of azo compounds.



 

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