JPH07102299B2 - Refining method for high temperature reducing gas - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for refining a high-temperature reducing gas, for example, hydrogen sulfide contained in a high-temperature reducing gas mixture such as a product gas of a coal gasification process. , A method for rationally removing sulfur compounds such as carbonyl sulfide.

[Conventional technology and its problems]

In recent years, due to depletion of petroleum resources and soaring prices, diversification of fuels (or raw materials) has been called for, and coal and heavy oil (tar sand oil, oil shale oil, Daqing heavy oil, Maya crude oil, vacuum residual oil, etc.) Is being developed. A typical example is a method in which coal or heavy oil is gasified and used for power generation or used as a fuel and a synthetic raw material.

However, this gasification product gas contains sulfur compounds such as hydrogen sulfide and carbonyl sulfide in the range of several hundreds to several thousand ppm, though it depends on the raw material coal or heavy oil. Must be removed to prevent poisoning.

There are a wet method and a dry method as the removal method, but the wet method is disadvantageous in terms of thermal economy because the processing gas must be cooled, and coexisting components (tar, naphthalene, halogen, NH 3
₍₃ , HCN, soot, etc.) removal or contamination of absorption liquid, equipment for pretreatment and wastewater treatment to prevent deterioration is required, which complicates the process.

On the other hand, the dry method is also advantageous in terms of thermo-economics and has a simple process structure. Therefore, a method of absorbing and removing an absorbent containing a metal oxide as a main component as a sulfide at a high temperature is generally used. As the absorbent, metal oxides such as Fe, Zn, Mo, Mn, Cu, W are used and reacted with H ₂ S and COS at 250 to 500 ° C. Taking Fe ₂ O ₃ as an example, To explain, it is said that the absorption reaction proceeds as shown in equations (1) to (7).

Fe ₂ O ₃ + H ₂ → 2FeO + H ₂ O …… (1) 3Fe ₂ O ₃ ＋ H ₂ → 2Fe ₃ O ₄ ＋ H ₂ O …… (2) Fe ₂ O ₃ ＋ CO → 2FeO + CO ₂ …… (3) 3Fe ₂ O _{3 + CO → 2Fe 3 O 4} + CO 2 ...... (4) FeO + H 2 S → FeS + H 2 O ...... (5) Fe 3 O 4 + H 2 + 3H 2 S → 3FeS + 4H 2 O ...... (6) Fe 3 O 4 + CO + 3H 2 S → 3FeS + 3H ₂ O + CO ₂ (7) Then, the absorbent after the absorption reaction is regenerated into a metal oxide by the oxygen-containing gas as shown in the formula (8), and the absorption and regeneration reactions are repeated to obtain high-temperature reducibility. The sulfur compound in the gas is recovered and removed as sulfurous acid gas.

4FeS + 7O ₂ → 2Fe ₂ O ₃ + 4SO ₂ (8) The absorbent used in this process is the above-mentioned metal oxide, either alone or supported on a heat-resistant porous material.
In the case of the moving bed system, a spherical or cylindrical molded product is generally used, and in the case of the fixed bed system, a honeycomb molded product is generally used.

Since a gas purified by removing sulfur compounds from a reducing gas such as coal gasification gas is used as an energy source, it is preferable to use a process for producing stable CO and H ₂ concentrations. )-(4) reactions must be suppressed as much as possible. In the moving bed system, the absorption process and the regeneration process are continuously repeated, so it is easy to overcome the above technical problems, but in the fixed bed system, the absorption process and the regeneration process are repeated intermittently. At the start of the reaction, the concentration of CO and H ₂ in the purified gas temporarily decreases, which is not practically preferable as a method for purifying the high-temperature reducing gas.

Therefore, the inventors of the present invention switched the fixed bed reactor to three towers in sequence and adsorbed and removed the sulfur compound contained in the high-temperature reducing gas with an absorbent containing a metal oxide as a main component. A step of regenerating the absorbed absorbent with an oxygen-containing gas, then a step of reducing the regenerated absorbent with a high-temperature reducing gas until the reducing gas concentration to be purified before and after the absorbent becomes the same, and then A method for refining a high-temperature reducing gas has been proposed, which stabilizes the concentration of the reducing gas in the purified gas by continuously repeating the step of aerating a high-temperature reducing gas and absorbing and removing the sulfur compound with the absorbent. (Japanese Patent Application No. 60-85412).

On the other hand, in the conventional high-temperature reducing gas purification method,
Sulfur recovery from SO ₂ gas uses coal as its reducing agent,
Since coke is used or reducing gas (CO, H ₂ etc.) and reducing catalyst (Co-Mo system etc.) and Claus catalyst etc. are used, the system becomes complicated, so operation and maintenance is not easy. Absent.

In addition, the process gas temperature during absorption and regeneration is generally 300 for each.
Since there is a large difference between ~ 500 ° C and 500 ~ 900 ° C, in the case of the conventional fixed bed system, the regeneration temperature becomes insufficient while the temperature rises up to the treatment temperature at the start of the process switching from absorption to regeneration. This results in a negative impact on the absorbent performance and the absorbent and leads to deterioration of the absorbent in the long run.

Further, it is necessary to prevent the mixture of SO ₂ gas from the reactor after the depressurization step and regeneration every time the process of absorption → regeneration is switched.
Therefore, before starting the process switching from regeneration to reduction, the SO ₂
In order to purge the gas, the depressurization operation had to be performed for a certain period of time, and careful operation control was essential, which made the operation considerably troublesome.

Therefore, the inventors of the present invention (1) absorb and remove sulfur compounds such as hydrogen sulfide and carbonyl sulfide contained in the high temperature reducing gas by absorbing the regenerated absorbent with the high temperature reducing gas before and after the absorbent. After reducing until the target reducing gas concentration becomes constant, in a method for refining a high temperature reducing gas that continuously repeats the step of absorbing and removing the sulfur compound, at least three reactors filled with an absorbent are used, reduction, absorption, SO ₂ reduction, constituted by the four steps of reproduction, supplying circulating gas from the regeneration step to the SO ₂ reduction step to convert the sulfur dioxide to elemental sulfur produced in the regeneration step and SO ₂ reduction step After recovering and removing as liquid sulfur, a part of the produced gas is introduced into the reduction process,
A method for purifying a high-temperature reducing gas, characterized in that the rest is returned to the regeneration step, and (2) In the method of (1) above, the high-temperature reducing gas is added to the circulating gas from the regeneration step to the SO ₂ reduction step. Proposed as Japanese Patent Application No. 62-56776, a method for refining a high-temperature reducing gas, which is characterized in that the temperature is raised to a temperature necessary for the SO ₂ reduction step by a combustion reaction with oxygen in the circulating gas. In addition, (3) a method of absorbing and removing a sulfur compound such as hydrogen sulfide and carbonyl sulfide contained in the high-temperature reducing gas with an absorbent by a method of absorbing and removing the sulfur compound using a regenerated absorbent. In the method of continuously refining a high temperature reducing gas, at least three reactors packed with an absorbent and at least one reactor packed with a Claus catalyst are used to absorb, pre-regenerate, regenerate and recover sulfur. By four steps Form, it was added a portion of the reducing gas and recovering sulfur circulating gas regeneration step, in the presence of oxygen, is combusted or reacting said reducing gas and recovering sulfur, required regeneration temperature and SO ₂ By ensuring the concentration, simple sulfur and sulfur compounds are generated in the regeneration step, and the simple sulfur in the recycling reactor outlet circulation gas is recovered and separated as liquid sulfur,
The circulating gas is passed through a reactor filled with the Claus catalyst to convert the sulfur compound in the circulating gas into elemental sulfur, which is recovered and removed as liquid sulfur, and at the same time, a part of the circulating gas after removal of the elemental sulfur is absorbed. A method for refining a high-temperature reducing gas, which is characterized in that it is introduced into the process and the rest is returned to the regeneration process, was proposed as Japanese Patent Application No. 62-95213.

[Object of the Invention]

The present invention provides a method for refining a high-temperature reducing gas capable of improving the performance in the regeneration step, that is, efficiently recovering elemental sulfur in order to further improve the economical efficiency as compared with the above-mentioned prior application method. is there.

[Means for solving problems]

The present invention is a method of absorbing and removing a sulfur compound such as hydrogen sulfide and carbonyl sulfide contained in a high temperature reducing gas with an absorbent, and a step of continuously absorbing and removing a sulfur compound using a regenerated absorbent. In the repeated refining method of a high temperature reducing gas, at least three reactors packed with an absorbent are used, and the three steps of absorption, preliminary regeneration and regeneration are used, and the reducing gas is contained in the circulating gas of the regeneration step. And / or in the presence of oxygen by adding a portion of the recovered sulfur in the system,
By reacting (or burning) the reducing gas and / or the recovered sulfur to secure a required regeneration temperature and SO ₂ concentration, elemental sulfur is generated in the regeneration step, and elemental sulfur in the recycle reactor outlet circulation gas is generated. The present invention relates to a method for purifying a high-temperature reducing gas, which comprises recovering and removing as a liquid sulfur, introducing a part of the circulating gas into an absorption step, and returning the remaining part to a regeneration step.

[Action]

In the present invention, a high-temperature reducing gas (combustible gas containing H ₂ , CO, etc.) and a part of sulfur recovered in the system (hereinafter, recovered sulfur) is burned in the circulation gas of the regeneration process to generate a reaction for regeneration. The inlet of the vessel is 600 to 1000 ° C, and the concentration of SO ₂ in the circulating gas is 0.1.
By maintaining the content in the recycle reactor in the absence of oxygen, the SO ₂ and H ₂ O in the circulating gas can be maintained by maintaining the amount of SO 5 to 5 vol%.
And a part of the CO ₂ gas or the like reacts with the absorbent (FeS) or between the gases as shown in the formulas (9) to (15), respectively, so that the elemental sulfur (S ₂ ), Hydrogen sulfide, carbonyl sulfide, hydrogen and carbon monoxide.

4FeS ＋ 2SO ₂ → 4FeO ＋ 3S ₂ …… (9) 6FeS ＋ 4SO ₂ → 2Fe ₃ O ₄ ＋ 5S ₂ …… (10) 8FeS ＋ 6SO ₂ → 4Fe ₂ O ₃ ＋ 7S ₂ …… (11) FeS ＋ H ₂ O → FeO + H ₂ S …… (12) 3FeS + 4H ₂ O → Fe ₃ O ₄ ＋ 3H ₂ S + H ₂ …… (13) 3FeS + 4CO ₂ → Fe ₃ O ₄ ＋ 3COS + CO …… (14) 2H ₂ S + SO ₂ → 3 / xSx + 2H ₂ O …… (15) (however, x = 2-8) COS + H ₂ O → H ₂ S + CO ₂ (16) After recovering and removing the above elemental sulfur as liquid sulfur, a part of the circulating gas is introduced into the absorption process, and the rest is used in the regeneration process. return.

The circulating gas to the regeneration process contains some gaseous sulfur and combustible gases such as by-products H ₂ S, COS, H ₂ and CO, which are one of high-temperature reducing gas and recovered sulfur. When the parts are burnt in the circulating gas, they burn together and serve to supplement heat in the regeneration process. In addition, by burning a part of the recovered sulfur, not only is the SO ₂ gas in the recycle gas maintained at a predetermined concentration, but it is also useful for supplementing heat in the regeneration process.

Therefore, the amount of the high-temperature reducing gas for combustion and the amount of recovered sulfur used can be considerably reduced by the above-mentioned auxiliary action, resulting in a more effective system. That is, the reaction (combustion) of the high-temperature reducing gas and the recovered sulfur contributes to the supplementary heat of the regeneration process and the performance improvement of the simple sulfur production in the regeneration process.

〔Example〕

Hereinafter, embodiments of the method of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, coal 1 is a small amount of air or oxygen 2,
Partial combustion and gasification are performed in the gasification furnace 3 to obtain a gasified crude gas (reducing gas) 4 containing H ₂ and CO as main components. This crude gas 4 is 10 mg of dust in the gas in the dust collector 5.
After being sufficiently removed to about / Nm ³ , it is supplied to the dedusting gasified gas 6 through a line 7 and a flow path switching valve 9 to, for example, the reactor 16 in the absorption step.

This dedusting gasification gas (hereinafter, gasification gas) 6 differs depending on the type of coal and gasification conditions, but in addition to dust,
~ Contains several 1000ppm of H ₂ S, COS, NH ₃ and a very small amount of HF, HCl, etc., the gas temperature is recovered by the steam heater at the outlet of the gasification furnace 3, 250 ~ 500 ℃, the pressure is gas The pressure is from normal pressure to 25 kg / cm ² G, though it depends on the type of the chemical conversion furnace 3.

In FIG. 1, a reactor 1 of identical structure filled with absorbent 19 is shown.
6,17,18 absorption process according to formulas (1) to (7), (9) to
Although a fixed bed type embodiment in which the regeneration step according to the equation (14) and the regeneration step are sequentially switched is shown, the present invention is not limited to the fixed bed type, and H ₂ S, COS, etc. in a reducing gas can be used. A process of repeating regeneration by the formulas (9) to (14) after absorbing and removing the sulfur compound with an absorbent can be applied to both fluidized bed type and moving bed type. Further, needless to say, the present invention can be applied to a multi-column fixed bed type other than the fixed bed type three tower switching for gas flow path switching.

Furthermore, the composition and shape of the absorbent are not limited in any way.

Here, a state where the absorption process is performed in the reactor 16, the preliminary regeneration process is performed in the reactor 17, and the regeneration process is performed in the reactor 18 will be described.

The gasification gas 6 is used for partial regeneration through the line 8, and the remaining whole amount is introduced into the reactor 16 through the line 7 and the flow path switching valve 9, so that the sulfur compound is usually reacted. At a temperature of 300 to 500 ° C., the gas is absorbed and removed by the absorbent 19 according to the equations (1) to (7), and the gas turbine is used as a purified gas 50 via the flow path switching valve 43 (not shown).
Is supplied to.

The pre-regeneration step is to raise the temperature of the gas in the system after the absorption step to the temperature required for the regeneration reaction, and is basically the same circulation system as the regeneration step.

That is, in the preliminary regeneration step, a part of the regenerated circulation gas is introduced into the reactor 17, and a part of the gasification gas 6 is heated in the heat exchanger 12 via the line 8 into the gas. And the gas after heating the air- or oxygen-containing gas 30 in the heat exchanger 31 66
Are supplied through the flow path switching valves 14 and 33, respectively, and the gasification gas 65 is burned in the regenerated circulation gas to preheat the reactor 17. The outlet gas 36 of the reactor 17 is cooled by the heat exchanger 39, merges with the regeneration process outlet circulation gas 51 through the flow path switching valve 44, and is introduced into the sulfur condenser 53.
From the circulating gas 51 that has exited the preliminary regeneration step and the regeneration step, the treated gas after the sulfur condenser 53 and the sulfur separator 57 collects and removes the elemental sulfur, and the blower 58 boosts the pressure, and a part of it is supplied to the absorption step. , The rest through the flow path switching valve 48, heat exchanger
After heating at 40, they are introduced into the reactor 18 and the reactor 17 via line 64 and circulated.

When the reactor 17 is heated to a predetermined temperature, the flow path switching valve 45 is opened and a part of the recycle gas 61 is introduced.

By adopting such a method, the internal temperature of the reactor 17 can be raised to the temperature required for regeneration before the reactor 18 finishes the regeneration process. When the reactor 17 reaches the required temperature, it is put in a standby state for the regeneration process while partially performing regeneration.

In addition, by providing this preliminary regeneration step, the intermittentness of the gas flow at the time of switching the steps of absorption → regeneration and regeneration → absorption in the fixed bed system is buffered and its continuity can be maintained, so that absorption of the absorbent can be maintained. Performance and reproduction performance are stabilized.

In the regeneration process, the gasification gas 65, the recovered sulfur 26 and the air or oxygen-containing gas 66 are supplied to the flow path switching valves 15 and 29, respectively.
And a recycle gas 64 line, and the gasification gas 65, recovered sulfur 26, and by-products in the circulation gas 64 are supplied.
By reacting (combusting) H ₂ S, COS, H ₂ , CO and gaseous sulfur (S ₂ ) at the inlet of the reactor 18, the predetermined regeneration temperature and the SO ₂ concentration in the circulating gas 64 can be adjusted. Maintaining and regenerating the absorbent 19 in the reactor 18 according to equations (9)-(14).

As the recovered sulfur 26, the one extracted from the circulating gas 51 or the one obtained by gasifying the liquid sulfur extracted from the later-described sulfur separator 57 to the line 83 is used.

If the combustible component is difficult to burn due to the low gas temperature, a combustor such as the absorbent 19 or a catalyst may be used to perform sufficient combustion.

In addition, the regeneration is carried out at a pressure of normal pressure to 40 kg / cm ² G and a reaction temperature of 600.
~ 1000 ℃, SV value (gas flow Nm ³ / h / absorbent capacity m ³ ) is 100
~20001 / h, and the circulating gas SO ₂ concentration is 0.1~5vol%,
The absorbent 19 is regenerated by using the equations (9) to (14). Under the above conditions, from the viewpoint of economy, the pressure is 15-30
It is preferable to set kg / cm ² , reaction temperature of 700 to 850 ° C., SV value of 200 to 8001 / h, and SO ₂ concentration of 1 to 4 vol% in the circulating gas.

In addition, the amount of recycle gas (based on the outlet of the reactor 18) is 5 to 60% of the amount of the gasification gas 6 received in the absorption process, and the amount of the recovered sulfur 26 injected into the regeneration process is 0 to 30% of the total amount of the recovered sulfur. %. The supply amount of the gasification gas 65 to the preliminary regeneration process and the regeneration process is calculated by the following relational expression.

V _Re / (V _Cg × C _S ) ＝ 0.5〜10 ・ ・ ・ (17) Where, V _{Re is the} amount of gasification gas supplied to the preliminary regeneration process and regeneration process (Nm ³ / h) V _Cg : To the absorption process Received gasification gas amount (Nm ³ / h) C _S : mol of (H ₂ S + COS) in the received gasification gas
Fraction (-) If the supply amount of the gasification gas 65 is out of the range of the numerical value obtained by the equation (17), it becomes ineffective.

Incidentally, in the present invention, the absorbent 19 after the absorption step, that is, the sulfurized absorbent 19 (mainly FeS) is almost iron trioxide (Fe ₃ O ₄ ) during pre-regeneration and regeneration. Therefore, for example, the step of reducing the regenerated absorbent (reducing Fe ₂ O ₃ to Fe ₃ O ₄ with a gasification gas) described in Japanese Patent Application No. 62-56776 previously proposed is unnecessary. After the regeneration, the absorption step can be immediately switched to after cooling the inside of the reactor and purging SO ₂ gas and the like.

By the way, the circulating gas 37 at the outlet of the reactor 18 in the regeneration step is cooled by the heat exchanger 40, and then elemental sulfur (produced sulfur) is recovered. First, the circulating gas 51 is stored in the sulfur condenser 53 at 130 to 250 ° C.
The sulfur in the circulating gas is recovered as liquid sulfur 81, stored in the sulfur separator 57, and extracted through the liquid sulfur 83 line.

The circulating gas from which the elemental sulfur has been recovered and removed is pressurized by the blower 58, and the amount of the gas, which is commensurate with the gasification gas 65, the recovered sulfur 26 and the air- or oxygen-containing gas 66 injected in the regeneration process, flows. It is fed via the path switching valve 20 to the inlet of the reactor 16 during the absorption process.

That is, as can be seen in FIG. 1, in the regeneration process, the gas to be handled is in the circulation system, so the gasification gas 65, the recovered sulfur 26 and the air or oxygen-containing gas from the outside of the system to the regeneration process.
When 66 is injected, gasified gas 65, recovered sulfur 26
And N ₂ and H other than O ₂ gas consumed in the combustion reaction of by-products H ₂ S, COS, H ₂ and CO in the circulating gas 59 and gaseous sulfur (S ₂ ).
₂ O, CO _2, etc. are accumulated in this circulation system, so in order to balance the gas amount in the circulation system, gasification gas 65, recovered sulfur
26 and the amount of air or oxygen-containing gas 66 injected,
It is necessary to extract it outside the circulation system (absorption process).

In addition, the remaining circulating gas 61 (the gas that was supplied to the partial absorption process from the circulating gas 59 after the simple sulfur was removed by the sulfur condenser 53)
The remaining circulating gas from which 60 is subtracted) is heated in the heat exchanger 40 via the flow path switching valve 48, and then supplied to the reactor 18 and the reactor 17 and circulated.

Here, the gas 60 supplied to the absorption step is the gasification gas 7
As a result, the residual SO ₂ and gaseous sulfur, etc. in the gas are mixed with the absorbent 19 at the front of the reactor 16 during the absorption process.
Is converted to H ₂ S gas by the following equations (18) to (20).

SO ₂ + 3H ₂ → H ₂ S + 2H ₂ O (18) SO ₂ + 3CO + H ₂ O → H ₂ S + 3CO ₂ ... (19) 1 / xSx + H ₂ → H ₂ S ... (20) (However, x = 2 8) The generated H ₂ S and the residual H ₂ S, COS, etc. in the gas have an SV value of 500 to 4
While passing through the reactor 16 under 0001 / h, the gasification gas 7
It is absorbed and removed together with the sulfur compounds therein.

When the regeneration step of the reactor 18 is completed, the reactor 17 is switched from the pre-regeneration step to the regeneration step, and the inside of the reactor 18 is then cooled.

That is, the flow path switching valves 15, 25, 29 and 34 are closed to
By introducing a part of the recycle gas 61 at a temperature of ~ 250 ° C into the reactor 18 via the flow path switching valve 48, the reactor 18
The inside is cooled to 300 to 500 ° C. so as to match the temperature of the gasification gas 7. After the cooling, the flow path switching valve before and after the reactor 18
11, 69 are opened and the flow path switching valves 47, 48 are closed, a part of the gasification gas 7 is introduced into the reactor 18, and the gas in the reactor 18 is purged. That is, immediately after the completion of the regeneration step, SO ₂ gas, gaseous sulfur, etc. remain in the reactor 18, so the reactor 18 outlet gas 37 is introduced into the circulation gas 63 line to perform the preliminary regeneration → regeneration step. It is sent to the switched reactor 17.

After the SO ₂ gas, gaseous sulfur, etc. in the reactor 18 have been purged, the flow path switching valves 22 and 49 are opened and the flow path switching valve 6
Close 9 and start the actual absorption process. Regarding the process switching of the reactor 18 and the reactor 17, in order to maintain continuity of the gas flow at the time of the process switching, regeneration is performed →
Absorption and pre-regeneration → regeneration process switching is done at the same time.
Then, the reactor 16 is switched to the absorption → preliminary regeneration process.

Further, in the regeneration step, the normal direct oxidation of the absorbent 19 by the air or the oxygen-containing gas 66 is not performed, and (9)
Since the absorbent 19 is regenerated by the reaction of equations (14) to (14), the flow rate of the air for regenerating the absorbent 19 or the oxygen-containing gas 66 can be greatly reduced. Compared with the case where the absorbent 19 is regenerated by normal direct oxidation, the amount of air can be reduced by about 20 to 50%, which greatly contributes to the reduction of power consumption in the high temperature reducing gas purification process.

Also, the injection amount of the combustion gasification gas 65 and the recovered sulfur 26, etc. should be supplied slightly larger than the theoretical combustion oxygen (O ₂ ) amount,
Also, since the generation of SO ₃ in the regeneration process can be suppressed by not regenerating the absorbent 19 by direct oxidation, the absorbent 1
It is possible to prevent by-production of sulfates such as FeSO ₄ , Fe ₂ (SO ₄ ) _{3 and the} like, which cause activity deterioration of 9.

Furthermore, the production of H ₂ S and COS in the reactor during the regeneration process depends on the concentrations of H ₂ O and CO ₂ in the circulating gas, the temperature, etc.
Regeneration conditions from the economical point of view (pressure: 15-30 kg / cm ² G,
At a temperature of 700 to 850 ° C. and an SV value of 200 to 8001 / h), the concentration in the circulating gas at the outlet of the reactor becomes about 100 to 5000 ppm.

In addition, when the regeneration of the absorbent 19 is insufficient and the absorption performance is deteriorated due to some reason such as a lapse of time or an operation error, the regeneration temperature is kept at 750 ° C. or higher and the conventional method is used. Regeneration is carried out by direct oxidation of the absorbent by O ₂ gas [making the Fe content in the absorbent completely oxidized (Fe ₂ O ₃ ) state] to recover the absorption and regeneration performance of the absorbent. Can be expected. In this case, the specification of Japanese Patent Application No. 62-56776)
The regeneration and reduction steps are carried out in one column as described in 1, and the absorption step is performed.

A calculation example of reproduction in the method of the present invention will be described below.

Calculation conditions: (1) Gasification gas 6 conditions Gasification gas flow rate = 800,000 Nm ³ / h Gasification gas composition (vol%) Gasification gas pressure = 20kg / cm ² G Gasification gas temperature = 400 ° C (2) Absorption process outlet gas H ₂ S concentration = 100ppm or less Calculation example Regeneration pressure = 20kg / cm ² G Regeneration circulation gas 64 Temperature (heat exchange Reactor 18 outlet gas temperature = 750 ° C SO ₂ concentration = 3vol% in the recycle gas, recycle gas 64, gasification gas required for regeneration 8
The calculation results for the main items such as the amount, the amount of regeneration air 30 and the amount of regeneration gas from the regeneration circulation gas 60 to the absorption reactor 16 are as follows.

<Calculation Results> 1) regeneration recycle gas amount = In about 185,000Nm ³ / h (regeneration reactor outlet of about 200,000 ³ / h) 2) gasification gas amount = about 7000Nm ³ / h ³⁾ regeneration air quantity = About 9400 Nm ³ / h 4) The amount of gas discharged to the absorption reactor = about 14800 Nm ³ / h or more, so the amount of gasification gas used is extremely small, about 0.9% of the amount of gasification gas 6 received, and the amount of regeneration air is Conventional regeneration method (direct oxidation of absorbent with O ₂ , amount of regeneration air = about 15000N
It turns out that it is more than 35% less than m ³ / h).

In addition, in FIG. 1, the flow path switching valves 10, 13, 21, 23, 24, 27, 28, 32, 41, 42, 46, 67, 68 which are not described are reactors.
It is normally closed when 16 is performing the absorption step, reactor 17 is performing the pre-regeneration step, and reactor 18 is performing the regeneration step. Also, the high temperature gas source 71, of the heat exchangers 12, 31 of 8 lines of gasification gas and 30 lines of air or oxygen-containing gas
72 and the cooling water 91 of the sulfur condenser 53 are not limited as long as they satisfy the heat exchange conditions.

〔The invention's effect〕

The high-temperature reducing gas purification method of the present invention has the following effects.

(1) It can handle all practical operating load ranges of gasifiers.

(2) In the regeneration step, before introducing the circulation gas into the regeneration reactor, a part of the gasification gas and the recovered sulfur are supplied into the circulation gas, and H ₂ S as a by-product in the circulation gas is supplied to them. , COS,
A method of burning with H ₂ CO, gaseous sulfur, etc. with air or an oxygen-containing gas to secure the required regeneration temperature and SO ₂ concentration, and not directly oxidizing the absorbent with oxygen (O ₂ ). In order to regenerate the absorbent by, in comparison with the case of regenerating the absorbent in a normal regeneration step (direct oxidation of the absorbent with O ₂ ), Two
Since it can be reduced by about 50%, it is possible to greatly reduce the power consumption.

(3) There is no need for the conventional reduction process of regenerated absorbent (reduction of Fe ₂ O ₃ to Fe ₃ O ₄ with gasification gas) and Claus reaction process, and the reaction process can be reduced by 2 processes, so operation Is greatly simplified.

(4) By a method of burning a gasification gas, a part of recovered sulfur, etc. in a theoretical combustion oxygen deficient region in a recycle gas and not directly oxidizing the absorbent with oxygen,
Since the by-product rate of sulfates such as FeSO ₄ and Fe ₂ (SO ₄ ) ₃ from the absorbent can be suppressed to a small level, it contributes to the prevention of performance deterioration of the absorbent.

[Brief description of drawings]

 FIG. 1 is a diagram for explaining one embodiment of the present invention.

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Claims (1)

[Claims] 1. A method of absorbing and removing a sulfur compound such as hydrogen sulfide and carbonyl sulfide contained in a high-temperature reducing gas by an absorbent, and continuously removing the sulfur compound by using a regenerated absorbent. In the method for refining a high-temperature reducing gas that is repeated as described above, at least three reactors packed with an absorbent are used, and the three steps of absorption, preliminary regeneration and regeneration are used, and the reducing gas is added to the circulating gas in the regeneration step. Gas and /
Alternatively, by adding a part of the sulfur recovered in the system and reacting the reducing gas and / or the recovered sulfur in the presence of oxygen to secure the necessary regeneration temperature and SO ₂ concentration, the sulfur in the regeneration step Is produced, and after recovering and removing the elemental sulfur in the circulation gas at the outlet of the regeneration reactor as liquid sulfur, a part of the circulation gas is introduced into the absorption step, and the rest is returned to the regeneration step. Gas purification method.