CN1125163C

CN1125163C - Coke-oven gas desulfurizing and decyanating process

Info

Publication number: CN1125163C
Application number: CN 00112225
Authority: CN
Inventors: 宋宝宁; 曹建元; 曹汉生
Original assignee: JIANGSU STEEL GROUP CO Ltd JIANGSU
Current assignee: JIANGSU STEEL GROUP CO Ltd JIANGSU
Priority date: 2000-04-20
Filing date: 2000-04-20
Publication date: 2003-10-22
Anticipated expiration: 2020-04-20
Also published as: CN1277245A

Abstract

The present invention discloses a process for desulphurizing and decyanating coke-oven gases. The process comprises the steps that the coke-oven gases come into a reverse contact with desulphurizing liquor in a desulphurizing tower after being initially cooled, electrically collected to remove tar and pressurized by blowing; hydrogen sulphide and hydrogen cyanide are removed through a chemical absorption reaction, a catalytic chemical reaction and a catalytic regeneration and oxidation reaction under the action of a composite catalyst containing OMC (sulphonated cobaltous polyphthalocyaninate) and picric acid (trinitrophenol). The process has the desuphfurization efficiency of more than 99.5% and the decyanation efficiency of more than 98%.

Description

A kind of desulfurization and decyanation technology of coke-oven gas

Technical field

The present invention relates to a kind of desulfurization and decyanation technology of coke-oven gas.

Background technology

At present, the coal gas desulfurization of domestic each large-scale coke-oven plant all adopts advanced A.S method and conventional A.D.A method, A.S method complex process, equipment and material is strict, the investment big, and H in the coal gas behind the thionizer ₂S content is still very high, is difficult to reach the specification of quality of town gas, and the desulfurization of A.D.A method is to be alkali source with sodium, and consumption is bigger, invests also very greatly, and therefore, working cost is also very high.

The single picric acid of the former employing of middle-size and small-size coke-oven-gas desulfurization and decyanation (trinitrophenol) is as catalyzer, and desulfuration efficiency is paced up and down all the time about 70%, coal gas H behind the thionizer ₂S content all the time can not be up to standard, and equipment corrosion is serious.

Summary of the invention

The objective of the invention is: the desulfurization and decyanation technology that a kind of coke-oven gas is provided, this technology is under the prerequisite that does not change original processing condition, with less investment, catalytic activity is good, desulfuration and decyanation efficient is high, and OMC (sulfonation gathers the phthalocyanine cobalt)--picric acid (trinitrophenol) is composite catalyst, removes the H in the coke-oven gas ₂S and HCN, desulfuration efficiency are greater than 99.5%, and decyanation efficient is greater than 98%.

Technical scheme of the present invention is: a kind of desulfurization and decyanation technology of coke-oven gas, its coke-oven gas enters after cold, electrically trapped tar oil, air blast pressurization just that thionizer and doctor solution are reverse to contact operation, in that OMC (sulfonation gathers the phthalocyanine cobalt)--picric acid (trinitrophenol) is under the effect of composite catalyst, removes hydrogen sulfide and prussic acid by chemical absorption reaction, catalyzed chemical reaction, catalytic regeneration oxidizing reaction.

The further technical scheme of the present invention is: a kind of desulfurization and decyanation technology of coke-oven gas, its coke-oven gas enters after cold, electrically trapped tar oil, air blast pressurization just that thionizer and doctor solution are reverse to contact operation, in that OMC (sulfonation gathers the phthalocyanine cobalt)--picric acid (trinitrophenol) is under the effect of composite catalyst, removes hydrogen sulfide and prussic acid by chemical absorption reaction, catalyzed chemical reaction, catalytic regeneration oxidizing reaction; Described doctor solution is carried salt again, extracts ammonium thiocyanate and ammonium thiosulfate.

H in the coke-oven gas ₂S and HCN do not react when being gaseous state, work as H ₂The S secondary that then takes place soluble in water dissociates:

In the time of 25 ℃, K ₁=9.1 * 10 ^-7

In the time of 25 ℃, K ₂=1.0 * 10 ^-15

K ₁" K ₂So, H in the solution ₂S is mainly with HS ^-Form exists, and solution is slightly acidic.Therefore just can effectively absorb H with alkaline solution ₂S gas.Ammonia is soluble in water, and solution is weakly alkaline, can with HS ^-Reaction generates NH ₄HS.HCN is soluble in water, when contacting with doctor solution, with NH wherein ₄ ⁺Reaction generates NH ₄CN.OMC is to be that the phthalocyanine of central ion is a macromolecular compound with the cobalt, and it is the same with picric acid all to have the oxygen of taking effect and redoxomorphism, is progressively become by oxidation state in sweetening process and goes back ortho states, is oxidation state in regenerative process with after oxygen in the air contacts.Sulfide reverts to NH through catalytic oxidation in the solution ₄OH continues desulfuration and decyanation, also takes place with some side reactions simultaneously, and its main chemical reactions is as follows:

1.H ₂The absorption reaction of S, HCN:

2. catalytic oxidation:

3. side reaction:

At H ₂In the two step ionization of S, the second step ionization equilibrium constant is much smaller than the equilibrium constant of the first step, and the effect of the catalyzer that catalytic oxidation desulfurization method uses mainly is to reduce H ₂S ionized activation energy of second step is accelerated ionization rate, and is promoted absorption reaction.

OMC is because its special chemical structural formula, and has very strong oxygen carrying capacity, makes S ^2-Very easily be oxidized to simple substance S or polysulfide, make CN in the solution ^-Fast with (NH ₄) ₂S _xReaction generates on-catalytic poisonous substance CNS ^-, solved CN ^-Poisoning problem to catalyzer.

In the desulfuration and decyanation process, the absorption reaction of HCN is exceedingly fast, and the generation of ammonium polysulfide is comparatively slow, and the sulfur granule that the picric acid catalyzed reaction generates is superfine little, helps putting forward the doctor positive dissolution rate, thereby accelerates the formation reaction of ammonium polysulfide.

Advantage of the present invention is:

1. the present invention does not change original processing condition, is alkali source with the ammonia in the coal gas, and OMC (sulfonation gathers the phthalocyanine cobalt)--picric acid (trinitrophenol) is the desulfurization composite catalyst.

2. picric acid (trinitrophenol) plays the promotor effect in OMC (sulfonation gathers the phthalocyanine cobalt) desulfuration and decyanation process, picric acid (trinitrophenol) can impel the suspension sulphur in the solution to be converted into elemental sulfur, be easy to generate ammonium polysulfide, therefore, to the decyanation particularly advantageous.

3. desulfurization waste liquor of the present invention can extract market NH salable through further processing ₄The CNS product, the resource of HCN has obtained fully effectively utilizing in the coal gas, can also further extract (NH ₄) ₂S ₂O ₃Product obtains favorable economic benefit.

4. the present invention makes full use of NH in the coal gas ₃Remove sour gas H ₂S, HCN needn't add alkali, save working cost, have relatively alleviated corrosion to equipment with the naphthoquinones method.

5. service temperature of the present invention still has very high desulfuration and decyanation efficient in the time of 30--40 ℃, do not need refrigerated forced cooling coal gas, and energy consumption is low.

6. the present invention adopts OMC--picric acid composite catalyst, comprehensive performance OMC and picric acid effect separately obtain best desulfuration and decyanation effect, and not only desulfuration efficiency reaches more than 99%, especially decyanation effect is also up to 98--99%, for other catalyzer can't be obtained.

7. turndown ratio of the present invention is big, and production practice show, H in coal gas ₂When factor fluctuations such as OMC concentration, secondary salt concentration, suspension sulphur content were big in S content and the doctor solution, very little to the effectiveness affects of desulfuration and decyanation, this had bigger Practical significance in day-to-day operation.

Description of drawings

The invention will be further described below in conjunction with embodiment:

Fig. 1 is the gas purification process schematic flow sheet;

Fig. 2 is a coal gas desulfurization decyanation technology schema;

Wherein: 1 thionizer; 2 regenerator columns; 3 regulator of level; 4 liquid seal troughs; 5 sulphur bubble groove; 6 catalyzer liquid pools; 7 circulation grooves; 8 plate-and-frame filter press; 9 pumps.

Embodiment

Embodiment: as shown in Figure 1, a kind of desulfurization and decyanation technology of coke-oven gas, its coke-oven gas enters after cold, electrically trapped tar oil, air blast pressurization just that thionizer and doctor solution are reverse to contact operation, in that OMC (sulfonation gathers the phthalocyanine cobalt)--picric acid (trinitrophenol) is under the effect of composite catalyst, removes hydrogen sulfide and prussic acid by chemical absorption reaction, catalyzed chemical reaction, catalytic regeneration oxidizing reaction.

As shown in Figure 2, the coke-oven gas behind the electrical tar precipitator enters thionizer, the reverse H that contacts in the coal gas of the desulfuration solution that coal gas is sent here with regenerator column in thionizer ₂S, HCN and part NH ₃Be desulfurized absorption, coal gas after the purification is gone out from cat head and is delivered to next procedure, doctor solution flows to circulation groove through liquid seal trough, use pumping toward the regenerator column bottom again, in Ta Nei and regeneration air and stream rising, catalyzer oxidation by air in the doctor solution and regenerating, doctor solution flows into regulator of level from the top, arrive the spray cycle desulfurization of thionizer top again, partial desulfurization liquid is extracted out from sulphur bubble groove, squeeze into plate-and-frame filter press press filtration sulphur with the press filtration pump, also have partial desulfurization liquid to send to three wastes treatment plant through the doctor solution recycle pump and carry salt, desulfurization is put into the doctor solution circulation groove with catalyzer after the liquid pool dissolving.

The flow velocity of coke-oven gas in thionizer is 0.3--0.45m/s, and liquid-gas ratio is 45--52l/m in the thionizer ³, the regenerator column blast intensity is 25--30m ³/ m ²N, coke-oven gas and doctor solution temperature are respectively 25--35 ℃ and 30--40 ℃, the composition of doctor solution: picric acid 0.07--0.15mg/l, OMC:24--27mg/l, suspension sulphur 6.25g/l, NH ₄CNS:150g/l, (NH ₄) ₂S ₂O ₃: 148g/l, volatilization ammonia: 4.60g/l, pH value: 9.0, desulfuration efficiency is greater than 99.5%, and decyanation efficient is greater than 98%.

Following table be second test texture ratio of the present invention:

G/m before the desulfurization ³G/m after the desulfurization ³Desulfuration efficiency %

H ₂S HCN H ₂S HCN H ₂S HCN

One 4.28 1.29 0.02 0.01 99.53 99.22

2 4.32 1.15 0.02 0.01 99.54 99.13

Claims

1. the desulfurization and decyanation technology of a coke-oven gas, its coke-oven gas enters after cold, electrically trapped tar oil, air blast pressurization just that thionizer and doctor solution are reverse to contact operation, under the effect of catalyzer, remove hydrogen sulfide and prussic acid by chemical absorption reaction, catalyzed chemical reaction, catalytic regeneration oxidizing reaction, it is characterized in that: catalyzer adopts poly-phthalocyanine cobalt--the trinitrophenol composite catalyst of sulfonation, doctor solution consist of trinitrophenol 0.07--0.15mg/l, poly-phthalocyanine cobalt: the 24--27mg/l of sulfonation, suspension sulphur 6.25g/l, NH ₄CNS:150g/l, (NH ₄) ₂S ₂O ₃: 148g/l, volatilization ammonia: 4.60g/l, the pH value of doctor solution is 9.0, and coke-oven gas and doctor solution temperature are respectively 25--35 ℃ and 30--40 ℃, and the flow velocity of coke-oven gas in thionizer is 0.3--0.45m/s, and liquid-gas ratio is 45--52l/m in the thionizer ³

2. the desulfurization and decyanation technology of coke-oven gas according to claim 1, it is characterized in that: described doctor solution is carried salt again, extracts ammonium thiocyanate and ammonium thiosulfate.