CN104587825A - Novel method for SCR and lime/gypsum wet desulfurization combined operation - Google Patents

Abstract

The invention relates to a novel method for SCR and lime/gypsum wet desulfurization combined operation. The method comprises the following steps: (1) controlling the alpha excess air coefficient to be between 1.05 and 1.02; and (2) adding 1mg/L of sodium hypochlorite into desulfurization slurry, and adjusting the pH of the desulfurization slurry to be between 5.5 and 6.2. According to the invention, the use amount of NH3 is reduced; the running resistance is reduced; the escape of NH3 is prevented; the removing rate of NOx is improved, so that the use amount of lime is reduce, the desulfurization resistance is improved greatly, and the desulfurization system is stable, and runs efficiently.

Description

The new method of a kind of SCR and lime/gypsum wet desulphurization cooperation

Technical field

The invention belongs to flue gases purification field, thermal power plant, the new method of especially a kind of SCR and lime/gypsum wet desulphurization cooperation.

Background technology

At present, coal-burning power plant adopts SCR denitration and wet desulfurizing process mostly, but this is two autonomous systems in power plant, but the system series operation again that these two systems work alone, sometimes it is unstable that denitration stabilizes desulfurization on the contrary, and desulfurization sometimes stabilizes denitration and goes wrong again, and coal-burning power plant adopts NH at present ₃method denitration and wet desulphurization are in the great majority, and the unit run under this desulphurization denitration exists a problem jointly.Namely the denitrification process first carried out adds NH ₃to NO _xreduction process.Thereafter the desulfurization carried out is CaSO ₃change into CaSO ₄oxidizing process.This process completely reverse general principle.

Will maintain certain excess air when coal is burned, but excess air coefficient hour improves denitration efficiency.When excess air coefficient is large, denitration not only declines, and also consumes a large amount of NH ₃and cause (NH ₄) ₂sO ₄blocking and a large amount of the escaping of ammonia.This just objectively requires these two independences and the system of series operation is put and studied under consideration.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, the new method of a kind of SCR and lime/gypsum wet desulphurization cooperation is provided.

The present invention solves its technical problem and takes following technical scheme to realize:

A new method for SCR and lime/gypsum wet desulphurization cooperation, is characterized in that the content of the method comprises:

(1) control α excess air coefficient is between 1.05-1.02;

(2) in desulfurization slurry, add the clorox of 1mg/L, regulate the pH of desulfurization slurry between 5.5-6.2.

Advantage of the present invention and good effect are:

1, present invention reduces NH ₃consumption, and running resistance is declined.

2, the inventive method prevents NH ₃escape.

3, invention increases the clearance of NOx.

4, present invention reduces pH value, make lime consumption reduce and significantly improve desulfuration efficiency.Add hypochlorite oxidation agent, desulphurization system is stablized, Effec-tive Function.

Detailed description of the invention

Be further described the invention process below, following examples are descriptive, are not determinate, can not limit protection scope of the present invention with this.

A new method for SCR and lime/gypsum wet desulphurization cooperation, the method based on general principle be:

1, denitration principle:

(1)

4NO+4NH ₃+O ₂→4N ₂+6H ₂O ①

6NO+6NH ₃→5N ₂+6H ₂O ②

(2)

2NO ₂+4NH ₃→3N ₂+6H ₂O ①

6NO ₂+4NH ₃→7N ₂+12H ₂O ②

1. and 2. in flue gas, NO accounts for more than 90%, from, have common law, and the NOx removing equal in quality under the condition 1. participated at aerobic needs more NH ₃, the denitration that namely aerobic participates in need consume more material.2. the NOx removing equal in quality under the condition of aerobic participation generates more H ₂o.The essence of reaction (1), (2) uses NH ₃nOx is reduced into N ₂process.This carries out under just objectively requiring few oxygen or oxygen free condition, but boiler combustion needs again to keep α excess air coefficient value, so it is the smaller the better to get α value in the process of denitration, also brings two to endanger greatly when aerobic is participated in.First adds NH ₃consumption and cause NH ₃escapement ratio increases.The second, the trend generating ammonium sulfate strengthens and causes resistance to increase.

Desulfurization is two processes.One 2SO ₂+ H ₂o+CaCO ₃→ Ca (HSO ₃) ₂+ CO ₂, this is the process of a hydrolysis and acid-base reaction.

The second, Ca (HSO ₃) ₂+ O ₂+ CaCO ₃+ 3H ₂o → 2CaSO ₄2H ₂o+2CO ₂, be oxidation reaction process.Also Ca (HSO can be written as from principle ₃) ₂+ O ₂→ CaSO ₄+ H ₂sO ₄this oxidation reaction process need have oxidant, the key of desulfuration efficiency is oxidation reaction, ensure that the mode be oxidized has two at the scene in running, namely increase excess air coefficient and blast air, increase excess air coefficient to conflict with denitration, blasting air is a reasonable manner, but is the amount of oxidant and the acid or alkali environment of oxidation number and oxidative calcium content most crucial for calcium sulfate oxidation calcium sulfate.

Method of the present invention is:

(1) control α excess air coefficient is between 1.05-1.02;

(2) in desulfurization slurry, add the clorox of 1mg/L, regulate the pH of desulfurization slurry between 5.5-6.2.

Claims (1)

1. a new method for SCR and lime/gypsum wet desulphurization cooperation, is characterized in that the content of the method comprises:

(1) control α excess air coefficient is between 1.05-1.02;

(2) in desulfurization slurry, add the clorox of 1mg/L, regulate the pH of desulfurization slurry between 5.5-6.2.