JPH02237613A - Method for refining high-temperature reducing gas - Google Patents

Abstract

PURPOSE:To reduce the term. rise of an absorbent in regeneration and to prevent the energy loss of the H2 and CO in the crude gasifying gas by partly connecting two absorption reactors in series, operating the reactors and almost completely sulfurizing the absorbent. CONSTITUTION:The ionic compds. (e.g. H2S and COS) contained in the high- temp. reducing gas are absorbed by the absorbent (e.g. Fe2O3) and removed. In this case, at least four reactors 17-20 packed with the absorbent 21 are used. The ionic compds. are absorbed by the absorbent in the absorption stage, the absorbent is regenerated by an oxygen-contg. gas in the regeneration stage, and the regenerated absorbent is reduced by the high-temp. gas in the reduction stage. Two reactors are partly operated in series in the absorption stage, and the other two reactors are partly regenerated in series at the time of operation. As a result, the temp. rise of the absorbent in regeneration is reduced, and the energy loss of the H2 and CO in the crude gasifying gas is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for purifying high-temperature reducing gas, for example,
The present invention relates to a method for rationally removing sulfur compounds such as hydrogen sulfide and carbonyl sulfide contained in high-temperature reducing gases such as gas produced in a coal gasification process.

[Conventional technology]

In recent years, due to the depletion of petroleum resources and soaring prices, it has become necessary to diversify fuels and raw materials.
Development of technologies for utilizing oil (oil shale oil, Daqing crude oil, Maya crude oil, vacuum residual oil, etc.) is underway.

The gas produced by gasification of these coals, heavy oils, etc. varies depending on the raw material coal and heavy oil, but it is several hundred to several thousand parts.
pm hydrogen sulfide (}125), carbonyl sulfide (COS
) and other sulfur compounds. These sulfur compounds are
It is necessary to remove it to prevent pollution or to prevent corrosion of downstream equipment.

As a removal method, the dry method is thermoeconomically advantageous and has a simple process configuration. Therefore, the above sulfur compound is brought into contact with an absorbent mainly composed of metal oxides at high temperature, and the metal oxides are removed. A common method is to remove metal sulfides as metal sulfides.

Absorbents include Pa, Zn, Mn+ Cu+ Mo
+First class gold? An oxide is used and brought into contact with hydrogen sulfide or carbonyl sulfide at 250 to 500°C. Taking the case of 11■S and FegO as an example, the absorption reaction is (1)
It is said that the process proceeds as shown in equation (4).

3Fe, o 3 + 8 2 - + 2Fe 2 0
．． ＋II! O ---------- (11
3Fe203+GO-+2Fe304+CO2 ---
-------- (2) FeJa + llz + 3H
zS → 3FeS + 41IzO ・------ (
3) Fez04+CO+3ToS-3FeS+311z
O0COz -- (4) Next, the absorbent after the absorption reaction is regenerated into the original metal oxide with oxygen-containing gas as shown in equation (5), and by repeating this absorption and regeneration reaction, it is converted into a high-temperature reducing gas. The sulfur compounds inside are collected and removed as SO2 gas.

4FeS+7Ch =2Fez(h +4S(h --
−−・−−−−−−−−− (5) The absorbent used in this process is the above-mentioned metal oxide alone or supported on a heat-resistant porous material. In the case of a fixed bed method, a honeycomb shape is usually used.

Therefore, the present inventors have developed a method for purifying high-temperature reducing gas by first absorbing and removing sulfur compounds contained in high-temperature reducing gas using an absorbent containing metal oxide as a main component.
He made the following suggestions:

■ A process of regenerating the absorbent that has absorbed sulfur compounds with an oxygen-containing gas, and then reducing the regenerated absorbent with a high a reducing gas until the concentration of the reducing gas to be purified before and after the absorbent becomes the same. A fixed-bed method characterized by stabilizing the reducing gas concentration in the purified gas by continuously repeating the process and finally the process of aerating high-temperature reducing gas and absorbing and removing sulfur compounds with an absorbent. Method for purifying high-temperature reducing gas (Japanese Patent Application No. 85412/1983).

In addition, the present inventors have proposed the following method for purifying high-temperature reducing gas by absorbing and removing sulfur compounds such as hydrogen sulfide and carbonyl sulfide contained in high-temperature reducing gas using an absorbent. I've been doing this.

■ After reducing the regenerated absorbent with high-temperature reducing gas until the concentration of the reducing gas to be purified before and after the absorbent becomes the same, the process of absorbing and removing sulfur compounds is repeated continuously. The purification method uses at least three reactors filled with an absorbent and consists of four steps: absorption, preliminary regeneration, regeneration, and reduction, and the high-temperature reducing gas is aerated and the sulfur compound is removed by the absorbent. A method for purifying high-temperature reducing gas characterized by stabilizing absorption and regeneration performance by absorption and removal (Patent Application No. 16781/1986)
No. 4) ■ A process in which sulfur compounds contained in high-temperature reducing gas are absorbed and removed by an absorbent, a preliminary regeneration process in which the temperature of the absorbent that has absorbed the sulfur compounds is raised until it reaches the temperature required for the regeneration reaction, and a process in which the regeneration reaction temperature is increased. It consists of four steps: a step of regenerating the reached absorbent with an oxygen-containing gas, and a step of reducing the regenerated absorbent with a high-temperature reducing gas until the reducing gas concentration before and after the absorbent becomes the same. The performance of absorption and regeneration at low loads can be stabilized by adjusting the amount of gas that is circulated in the process, or by adjusting the amount of recycle gas and using the combustion heat of the high-temperature reducing gas supplied to the regeneration process. A method for purifying high-temperature reducing gases characterized by
No. 167815). ■ Absorption to absorb and remove sulfur compounds with an absorbent? , a regeneration step in which the absorbent is regenerated with an oxygen-containing gas, a cooling step after the completion of the regeneration step, and the regenerated absorbent is reduced with a high > mA original gas until the reducing gas concentration before and after the absorbent becomes the same. Purification of high-temperature reducing gas is comprised of four steps, and in the regeneration step, the special feature is to continuously recover heat from the high-temperature gas at the outlet of the regeneration reactor to stabilize absorption and regeneration performance. Method (Special application 1986)
-27441).

[Problem to be solved by the invention]

The fixed-bed gas purification system proposed above consists of a reaction system consisting of absorption, regeneration, and reduction steps, and a downstream sulfur recovery system that processes the SO gas released from the regeneration system. In order to obtain stable performance over a period of time, it is necessary to employ systems and methods that suppress deterioration of the absorbent.

One of the causes of absorbent deterioration is thermal deterioration due to temperature rise during regeneration.

For example, when iron oxide is used as an absorbent, during regeneration,
In the regeneration reactor, oxygen contained in the regeneration gas and iron compounds contained in the absorbent undergo an oxidation reaction, generating heat. The temperature of the absorbent rises due to the accumulation of this reaction heat, and when the heat resistance limit temperature of the absorbent is exceeded, damage to the carrier or sintering of iron in the absorbent occurs, resulting in a decrease in absorption capacity. It is necessary to suppress the temperature rise exceeding the heat resistance limit of the agent as much as possible.

In subsequent research, the present inventors found that the temperature increase during regeneration was largely influenced by the reaction heat of Fe+On remaining unreacted during the absorption process.

In a fixed-bed gas purification system that uses one absorption reactor to perform the absorption process, in order to reduce the sulfur compounds in the gas after passing through the absorption reactor to a predetermined concentration or less, it is necessary to use an absorbent. It is necessary to suppress the sulfidation rate (the ratio of Fe in the absorbent to FeS) to about 10 to 50%.

That is, at the start of the absorption process, the iron compounds in the absorbent, which have the form of Fe and Oa, gradually change to FeS from the upstream side, so at the end of the absorption process,
This means that 50-90% of unreacted Fl3!04 must be present in the absorbent.

Therefore, during the regeneration step, this unreacted FexOa causes the reaction of formula (6) shown below, causing a rise in temperature.

FeJa +'/zOz -3/zFezOz -”
'-''-'-'-1' (6) Since the reaction in equation (6) is unrelated to the original repopulation reaction (5) 2, it is desirable to devise a way to prevent this reaction from occurring. However, in an absorption system using one absorption reactor column, it is not possible to completely eliminate the coexistence of FeS and Feig4 in the absorbent after the absorption step.

On the other hand, after the absorption step, unreacted Fe30. The coexistence of these causes various inconveniences as described below.

Unreacted Fe304 in the absorption process undergoes the following reaction in the subsequent regeneration and reduction process.

That is, in the regeneration step, Fe.
In the next reduction step, F(3zO3 changes to Fe30., for example, by the reaction of equations (1) and (2). In the regeneration step, the temperature rises as described above, and absorption This causes thermal deterioration of the agent, while consuming oxygen in the regeneration gas.

Oxygen in the regeneration gas is originally converted to l by reaction (5) 2.
The consumption of oxygen by this Fe+On is redundant.

In addition, in the reduction process, unreacted Fe30 in the absorption process is
．． is converted to Fezes in the regeneration process and becomes Fe30m again through the reactions of equations (1) and (2), and t in the gasified gas
t. Consumes z+co. This 11■,CO is the unreacted Fe30. If it does not exist, it can be said to be a wasteful consumption that cannot be consumed, and since it is essentially HZ+ co of gasification gas, it becomes a cause of fuel source loss for the gas turbine downstream of the gas purification device.

In addition, as an absorbent, other than iron, Zn, Mn, Cu,
A similar problem occurs even when an oxide such as Mo+ is used.

The present invention has been made to solve problems such as alleviation of absorbent temperature rise during regeneration and energy loss of 11 CO in crude gasification gas.

[Means to solve the problem]

The present invention solves the above-mentioned problems by operating some of the absorption reactors arranged in two columns in series to almost completely sulfurize the absorbed M.

That is, the present invention uses an absorbent to absorb and absorb sulfur compounds such as hydrogen sulfide and carbonyl sulfide contained in high-temperature reducing gases.
The removal method uses at least four reactors filled with absorbent, and consists of three steps: an absorption step, a regeneration step, and a reduction step. The present invention provides a method for producing a high-temperature reducing gas, which incorporates a regeneration step and a regeneration step in which two columns are arranged in series and operated in a part thereof.

[Effect]

The conventional process in which the absorption process is operated in one absorption reactor column has been changed to a process in which two columns are operated in series in each of the absorption and regeneration processes, as described above, and the absorbent after the absorption process is By increasing the sulfidation rate, that is, the utilization rate of the absorbent, which was conventionally 10 to 50%, to 100% and making the function of the absorbent effectively manifest, the following advantages occur.

Although the present invention is not limited thereto, the following FezO. An example will be explained in which the absorbent is used as an absorbent.

When the absorption process is carried out by single column operation, from the viewpoint of effective utilization of the absorbent, it is preferable to switch the absorption process with the sulfidation rate as high as possible within the allowable range of the concentration of the sulfur compound released. The absorption time is the time it takes for the extracted sulfur compound to reach the permissible limit concentration, whereas in the method of the present invention, it takes until almost all of the iron oxide in the absorbent for 1 column becomes FeS. You can take your time.

If the absorption time is calculated by assuming the same amount of absorbent for both, the method of the present invention can take longer than the case of operating the 1-column alone. On the other hand, if we calculate the amount of absorbent required for the same absorption time, the amount of absorbent required in the method of the present invention is smaller than that in the case of single column operation.
About 75% is good. From this, the present invention has the advantage that the reactor can be made more compact than the conventional method. Moreover, in the regeneration process, Fe
30. Since there is almost no regeneration required for the oxidation reaction of FesOa? The amount of air needed is small, and the air flow for regeneration is about 95% compared to single tower operation (assuming the sulfurization rate is 25%). Therefore, approximately 5% of the amount of oxygen consumed by the remaining Fezes is no longer needed.
This leads to a reduction in the amount of air used for regeneration, reduces the blower capacity for air supply, and is effective in reducing power consumption.

In addition, in the reduction process, as mentioned above, PexOa due to unreacted PexOa in the absorption process in the single column operation is
Since there is no reduction reaction of ezO3, there is no wasteful consumption of CO, which is the fuel source of the gas turbine.

Furthermore, it can also be characterized in terms of reaction.

That is, in the regeneration process, only the oxidation reaction of FeS mainly occurs, which not only avoids the abnormal high temperature caused by the oxidation of Feze4 in the conventional method, but also stabilizes the gas temperature and SO concentration at the reactor outlet in the regeneration process. It also contributes to The heat of the high-temperature gas at the outlet of the reactor in the regeneration process, which is recovered by the heat exchanger installed at the reaction outlet in the regeneration process, is introduced into the reactor in the regeneration process via the S recovery system. Since it is used for gas reheating, it is important to stabilize the gas temperature at the outlet of the reactor during the regeneration process in order to ensure stable operation as a total system. On the other hand, as mentioned above, the concentration of SO8 gas generated from the reactor in the regeneration process is small, and stable performance can be obtained in the downstream sulfur recovery system.

The present invention has a large ripple effect as described above, and can be said to be an extremely effective method in a total system for purifying high-temperature reducing gas using a fixed bed method.

〔Example〕

FIG. 1 is a flow diagram showing one embodiment of the method of the present invention.

In FIG. 1, 1, 2. 4 and 54 are ozs,
Dedusting high-temperature reducing gas line containing sulfur compounds such as cos, 3.5-8, 42-45 are the same gas flow path switching valves,
9-12 are switching valves for relatively high concentration sulfur compound-containing gas coming out of the reactors in the regeneration process and reduction process; 17-?
0 is a reactor filled with 2 liters of absorbent divided into multiple stages (four stages in this case), 30 to 33 are gas flow switching valves for switching the absorption process to two column series operation, and 34 to 37 are regeneration units. Gas flow switching valve for introducing the reactor outlet gas in one process into the reactor in the other regeneration process, 38-4L
50 to 53 are gas flow switching valves for supplying regeneration gas to the reactor in the regeneration process; 50 to 53 are gas flow switching valves for purified gas from the reactor in the absorption process; 58 is a purified gas extraction line; 63 is a regeneration gas circulation line, 57 is a branch line of gas line 78 which will be described later, 56 is a flow path switching valve, 59 and 60 are lines and flow path switching valves for supplying air or oxygen-containing gas, 55. 62 and 69
61 is a heat exchanger, 64 is a gas line whose temperature is lowered and contains a relatively high concentration of sulfur compounds, 67 is an SO₂ reduction reactor, 7L is a sulfur condenser, and 61. 68. 70, 72, 74
．． 75 and 77 are gas lines, 73 is a sulfur mist separator, 76 is a blower, 80 is liquid sulfur (recovered sulfur)
It's a line. Note that ■. on the right side of the reactor 20 in FIG.
(2) is connected to (2) and (2) on the left side of the reactor 17, respectively.

In FIG. 1, a reactor 1 of the same structure filled with an absorbent 21 is shown.
7 to 20 (1), (reduction step according to formula 21, (3)
, (Although this shows an embodiment in which the absorption step using Equation 41 and the regeneration step using Equation (5) are sequentially switched, the present invention is not limited to a fixed bed.
After absorbing and removing sulfur compounds such as S and COS with an absorbent,
(5) If the process involves repeated regeneration by 2, fluidized bed method is used.
Applicable to any moving floor. It goes without saying that the present invention can also be applied to fixed beds with four or more towers.

Furthermore, although there are no limitations to the composition or shape of the absorbent, here F+40. The following describes the case where is used as an absorbent.

The high-temperature reducing gas containing sulfur compounds such as II, S, and COS in line 1 is, for example, the gasified gas of coal that has been dedusted with a dust collector (not shown) to a dust concentration of about 10 mg/Nm3. Although it differs depending on the type of gas and gasification conditions, in addition to dust, there may be several tens to several thousand ρppm of HgS.
, COS, NHs and halogens, etc.
The gas temperature is 250~s due to heat recovery at the outlet during gasification.
Although the pressure varies depending on the shape of the gasifier, it is usually normal pressure to 25 kg/cmtG.

Figure 1 shows reactor 17. Regeneration process is carried out in 18, reactor 19
2 shows a state in which an absorption process is performed in the reactor 20, and a reduction process is performed in the reactor 20.

FIG. 2 is a diagram showing an example of the time schedule of the absorption, regeneration, and reduction steps of the reactors in this example, and the reactors 17 to 20 are Nos. 1 and 20, respectively. l-No. 4.

Here, regarding the absorption (desulfurization), regeneration and reduction processes and operation of the sulfur recovery system, see Section 3. 1 will be described below based on the time schedule of FIG. 2, assuming that the dedusting gasification gas is carried out at the same pressure (normal pressure to about 30 kg/cm2G).

In FIG. 1, the dedusting gasification gas in the line 1 is supplied to the reactor 19 through the flow path switching hub 7, and the sulfur compounds in the gas are normally at 300 to 500°C, (3)
, (2) is absorbed and removed by the absorbent 2 by the type 41, becomes purified gas, and is supplied from the line 58 to the gas turbine (not shown) via the flow path switching valve 52.

Reactors l7 and 18 during the regeneration process are connected by line 26?
- The outlet gas of the reactor 17 is introduced into the reactor l8 via the gas flow path switching valve 35. FIG. 1 shows the state of reactor 17 4 hours after entering the regeneration process. In the time schedule shown in FIG. 2, the regeneration of the absorbent is completed in 8 hours, but the regeneration is almost completed within the first 6 hours, and the remaining 2 hours are spent on completing the regeneration and cooling. Therefore, the net regeneration time is about 6 hours, and at the end of the 4-hour regeneration time, the absorbent in the reactor 17 has been regenerated by approximately 28 hours.

4 hours after the start of regeneration of reactor 17, the previous reactor 20
and 17 are replaced by those of reactors 17 and 18.

After approximately 6 hours of regeneration of the reactor 17, unreacted oxygen gas (0.0cm) comes out, but unreacted oxygen gas (0.0cm) comes out at the outlet of the reactor 17.
will be used to regenerate the absorbent in the latter stage reactor 1B, and along with complete regeneration and cooling of the reactor 17, the reactor 1
8 is played back. The regeneration step in the method of the present invention is
It is characterized by operating two columns in series, and the gas introduced into the regeneration reactor after the absorption step is the gas that has been used for regeneration in the other regeneration reactor. During the regeneration process, the oxygen gas concentration in the reactor outlet gas changes from low to high. That is, at the start of the regeneration process, the oxygen concentration in the regeneration inlet gas is low, but as the regeneration progresses, the oxygen concentration in the gas gradually increases, which is advantageous in terms of preventing the absorbent from becoming high in temperature. In addition, because the two-column regeneration is carried out in series, there is an advantage that oxygen gas can be prevented from leaking into the sulfur recovery system located downstream of the reactor in the regeneration process. Therefore, the reactors in the two towers connected in series in the front and rear regeneration steps can receive oxygen-containing gas even after the regeneration is completed, making it possible to introduce a cooling step to recover the heat stored in the absorbent and complete the regeneration.

Reactor 19 is in a state where 2 hours have passed since the start of the absorption process.

The reactor was filled with an amount of absorbent that would require 6 hours for the absorbent to completely break through, and after 2 hours, the reactor outlet still had sufficient absorption capacity. H.
The Sfi degree is below a predetermined limit concentration. For this reason,
At this point, the absorption process is carried out using a one-column operation. As the absorption process progresses further, unabsorbed sulfur compounds begin to come out from the reactor outlet, and the concentration exceeds the predetermined concentration from about 4 hours after the start of absorption.From this point on, the two columns are operated in series, and the reaction after the reduction process has been completed. The outlet gas of the reactor 19 is introduced into the reactor 20 via the flow path switching valve 32 and the line 24 . If the absorption process proceeds in this state, the reactor 19 will become completely FeS and will have no ability to absorb sulfur compounds at all, so at this point the gas flow path will be switched and the absorption operation will be performed by the reactor 20 alone. The reactor 19 that has been completely converted into FeS will then proceed to the regeneration step, and the outlet gas of the reactor 18 is introduced via the line 27 and the flow path switching valve 36. As mentioned above, since the concentration of oxygen gas in the outlet gas of the reactor 18 gradually increases from a low concentration, mild regeneration can be performed.

By combining the single-column operation and the two-column series operation in the absorption process in this way, it is possible to always create a state in which no unreacted substances coexist in the absorbent after the absorption process.

While the reactor 19 is performing the absorption process in the L column alone, the reactor 20 is in the reduction process, and the reducing gas is gas? Inn 4
The gas is introduced into the reactor 20 via a flow path switching valve 45 from a gas line 54 branched from the gas line 54 .

In the reactor, during the regeneration process, a part of FeS reacts with S (h) to form iron sulfate (Fet (so.) 3 as an impurity).
) is accumulated, which is decomposed by the next reaction during the reduction process to form SO. occurs.

1'+3(504)3+ rollz=2Fes+sO
z +10HzOFG (S04) z + IOco
= 2FeS + Sow + lOcO2 this SO
The outlet gas l6 of the reactor 20 containing SO2 is combined with the gas containing SO2 after the regeneration treatment via the flow path switching valve l2, cooled by the heat exchanger 62, and sent to the sulfur recovery system via the line 64. will be introduced in The gas transferred to the sulfur recovery system is transferred to the line 66, SO■ reduction reactor 67, heat exchanger 69,
Line 70 passes through the sulfur condenser 71 to the sulfur separator 7
3, and sulfur is recovered from line 80. Thereafter, the gas from which the sulfur has been separated is supplied with air or oxygen-containing gas from the line 59 by the blower 76, and is sent to the heat exchanger 62 via the line 61, where it is raised to the temperature required for the regeneration reaction. , is returned to the regeneration gas circulation line 63.

? The gas returned to the line 63 is introduced into the reactors 17 and 18 during regeneration through the flow path switching valve 38, and after contributing to the promotion of the regeneration reaction, is passed through the flow path switching valve 10 in the same manner as described above. It becomes a circulating gas.

The flow rate of the reducing gas 54 is approximately 1 to 10% of the dedusting gasification gas in the line 1, and is determined in balance with the amount of reducing gas (H.+CO) required in the ζSO■ reduction process.

When the reactor 19 completes the absorption process, the next step is the regeneration process, but at the same time, the reactor 17 goes to the reduction process, the reactor 18 goes to the regeneration process in series with reactor 19, and the reactor 20 goes to the desulfurization process. I will change it.

When the load is low, the flow rate of high temperature reducing gas in line 1 decreases, or when low sulfur coal is used, it takes a long time to completely destroy the absorbent in the absorption process. In such cases, it is possible to change to a system that operates without completely allowing the absorbent to break through.

At this time, the amount of FeS in the absorbent produced by the absorption reactions of equations (3) and (4) will be smaller than usual, and the heat amount of the regeneration reaction will be ?
It is becoming increasingly difficult to maintain the heat balance of the regeneration system.

If the load becomes less than a predetermined value (for example, less than 50%) and it becomes difficult to maintain a heat balance, a corresponding method may be adopted in which a portion of the sulfur condenser 71 of the sulfur recovery system is put into high-bus mode.

At that time, the bypass gas contains sulfur components such as His and gaseous sulfur, and these sulfur components are combusted at the inlet of the regeneration reactor or within the reactor, so they contribute to reheating within the regeneration system. becomes.

Removal of SO gas generated in the regeneration reaction includes recovery and removal as simple sulfur by SO2 reduction reaction alone or a combination of SO reduction reaction and Claus reaction, recovery and removal as gypsum by wet reaction with lime, etc. However, there are no restrictions on which method to use.

Here, a method for recovering and removing sulfur as an elemental sulfur by the reduction reaction of the above-mentioned formulas 01) to 03) will be explained.

The reducing gas from line 2 necessary for the SO2 reduction reaction is
A part of the dedusting gasification gas in line 1 is used, and through the flow path switching valve 3, it is used for SO ■ reduction and sulfur conversion. device 67
is supplied to With this gas, the SO2 gas contained in the gas from the line 64 after the regeneration process undergoes a reaction of the (11) to O1 formula to form 1123, simple sulfur, and the like.

SOi+31Iz →IhS+2LO −−−−−−
−． −． ．． ．． ．． ．． ．． ．． ．． -,,-,,-・00soz+
2oz −” to Sx +211 zO −1−−−
−−−−−− 02) SO2+211! S-+'8Sx
+ 211 zO −1−−−−−−θ Yutadashi x
= 2 to 8, then 130 to 2 in the heat exchanger 69 and sulfur condenser 71
The sulfur is cooled to 00°C, separated from gas components in a sulfur separator 73, and elemental sulfur is taken out of the system through a line 80.

In this way, most of the SOt gas produced in the regeneration reaction is removed and becomes the processing gas (gas in the regeneration gas circulation line 63) of the reactor in the regeneration process.

Note that the reducing gas used here is from line 5 after purification.
Naturally, gasification gas No. 8 is more preferable.

In the method of the present invention, the gas flow direction in the regeneration step is opposite to the flow direction during absorption, but the FeS distribution in the absorbent at the end of the absorption step is almost uniform regardless of whether it is upstream or downstream. The flow of the regeneration gas can be either forward flow or reverse flow. Further, the flow of the reducing gas can be either forward flow or reverse flow.

〔Effect of the invention〕

According to the method of the present invention, at least four reactors filled with an absorbent are used, and the absorbent is completely sulfurized by using two reactors, which consist of absorption, regeneration, and reduction steps. Compared to conventional fixed bed desulfurization methods, this method has the following effects.

(1) By effectively utilizing the absorbent during the absorption process, the amount of absorbent required can be reduced to about 374.

(2) During the regeneration process, unreacted (unsulfurized) Fe. O. This solves the temperature rise problem caused by the heat of reaction, protects the absorbent from thermal deterioration, and extends its life.

・During the regeneration process, the amount of regeneration air required for oxidizing unreacted (unsulfurized) Feze4 etc. can be reduced by about 5%.
As a result, it contributes to energy savings such as power consumption.

φ Also, since only the oxidation reaction of FeS etc. mainly occurs during the regeneration process, there is little change in the gas temperature and sotfA degree at the reactor outlet during the regeneration process, making it more stable.

・Unreacted (unsulfurized) Fe30 during the reduction process and absorption process
．． Fe. O. If, for reduction to etc.
Since there is no consumption of CO, loss of ++Z and CO used as fuel for gas turbines can be prevented.

As described above, the present invention can realize an effective method in a total system of a high-temperature reducing gas purification method.

[Brief explanation of drawings]

FIG. 1 is a flow diagram of one embodiment of the method of the present invention, and the second
The figure is an explanatory diagram showing an example of a time schedule for absorption, regeneration, and reduction cycles in the same embodiment. 1, 2, 4. 54--High temperature reducing gas line,
17, 18, 19, 20--Reactor, 58--Refined gas extraction line, 63-- Regeneration gas circulation line. , 64- Sulfur compound-containing gas line, 62. 69-
・One heat exchanger, 67- Sulfur recovery device, 73- Sulfur mist separator.

Claims (1)

[Claims] A purification method in which sulfur compounds contained in a high-temperature reducing gas are absorbed and removed by an absorbent, an absorption step in which at least four reactors filled with an absorbent are used and the sulfur compounds are absorbed and removed by the absorbent; It consists of three steps: a regeneration step in which the absorbent is regenerated with an oxygen-containing gas, and a reduction step in which the regenerated absorbent is reduced with a high-temperature reducing gas. A method for purifying a high-temperature reducing gas, characterized in that a part of the method incorporates a regeneration step in which two columns are operated in series.