JPH0278416A - Method for refining high-temperature reducing gas - Google Patents

Abstract

PURPOSE:To prevent the temp. rise of an adsorbent in regeneration by using at least four reactors packed with the adsorbent, applying adsorption, preregeneration, regeneration, cooling, and reduction, and completely serially performing preregeneration, regeneration, and cooling. CONSTITUTION:At least four reactors 21-24 packed with an adsorbent 25 are used, and an adsorption stage for adsorbing and removing the sulfur compd. in a high-temp. reducing gas with the adsorbent, the preregeneration and regeneration stages for regenerating the adsorbent with an oxygen-contg. gas, a cooling stage after the regeneration stage, and a reducing stage for reducing the regenerated adsorbent with the high-temp. reducing gas until the concns. of the reducing gas before and after the adsorbent are equalized are applied. The regeneration stage and the preregeneration stage are connected in series, a line for mixing the high-temp. gas leaving the regeneration stage into the gas leaving the preregeneration stage is provided, and the reaction heat in regeneration is continuously recovered even when the regeneration stage is switched. In addition, an SO2-contg. gas generated in the preregeneration, regeneration, and reduction stages is supplied to an S recovery system.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field 1 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 essential to diversify fuels (or raw materials). 4H, etc.) is being developed.

This gasification product gas differs depending on the raw material coal and tR quality oil, but the hydrogen sulfide (I
Contains sulfur compounds such as I, S) and carbonyl sulfide (C03). These sulfur compounds must be removed to prevent pollution or corrosion of downstream equipment.

As a removal method, a dry method is thermoeconomically advantageous and has a simple process configuration. A common method is to remove substances as metal sulfides.

Absorbents include Fc, Zn, Mn, Cu, Mo
, W″S, metal oxides of 250-500
When contacted with hydrogen sulfide or carbonyl sulfide at °C, I+
, S and Fee's as an example, the absorption reaction is said to proceed as shown in equations (1) to (4).

3FeyO* 4-Hl' 2FeJa )IIt
O”””””””(1)3FetOs 4 Co −+
2FO3044Co,------------
(2) Feff04 j-li! +3H? S->a
FeS+411?0---------(3)Fef
fO,) Co) at(ts->3FeS+311t
04 C0f---(4) Next, the absorbent after the absorption reaction is regenerated into the original metal oxide using an oxygen-containing gas as shown in equation (5), and by repeating this absorption and regeneration reaction, high-temperature reduction is achieved. The sulfur compounds in the gas are collected and removed as SO, gas.

4FeS-1-701->2Fa*O,l 4SOf-
−−−−−−−−−−−−−(5) The absorbent used in this process includes the above-mentioned metal oxide alone or supported on a heat-resistant porous material; In the case of a fixed bed method, it is molded into a spherical or cylindrical shape, and in the case of a fixed bed method, it is molded into a honeycomb shape.

The present inventors have previously proposed the following method for purifying high-temperature reducing gas by absorbing and removing sulfur compounds contained in high-temperature reducing gas using an absorbent mainly composed of metal oxides. I made a suggestion.

■The process of regenerating the absorbent that has absorbed sulfur compounds with an oxygen-containing gas, and then reducing the regenerated absorbent with a high-temperature reducing gas until the concentration of the reducing gas to be purified before and after the absorbent becomes the same. A fixed-bed high-temperature method characterized by stabilizing the reducing gas concentration in the purified gas by continuously repeating the process and finally the step of aerating high-temperature reducing gas and absorbing and removing sulfur compounds with an absorbent. Method for purifying 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 it.

■The regenerated absorbent is heated before and after the absorbent using high-temperature reducing gas.
I! A method for purifying high-temperature reducing gas that continuously repeats the process of absorbing and removing sulfur compounds after reduction until the target reducing gas concentration becomes the same, using at least three reactors filled with absorbent. use, absorb, pre-regenerate,
[A high-temperature process consisting of four steps of regeneration and reduction, characterized by stabilizing absorption and regeneration performance by aerating the high-temperature reducing gas and absorbing and removing the sulfur compounds with the absorbent. Method for purifying reducing gas (Patent application 1678-1988)
No. 14).

■High school 7! ! A process of absorbing and removing sulfur compounds contained in reducing gas with an absorbent, the absorbent that has absorbed the sulfur compounds is
A preliminary regeneration step in which the temperature is raised until it reaches the temperature required for the rl bioreaction, a step in which the absorbent that has reached the rlI bioreaction temperature is heated with an oxygen-containing gas, and the regenerated absorbent is heated before and after the absorbent with a high temperature reducing gas. The process consists of four stages of reducing until the reducing gas concentration of A method for purifying high-temperature reducing gas (Japanese Patent Application No. 167815/1982), which is characterized by stabilizing absorption and regeneration performance at low loads by utilizing the combustion heat of high-temperature reducing gas.

■Absorption process in which sulfur compounds are absorbed and removed by an absorbent, regeneration process in which the absorbent is regenerated with oxygen-containing gas, cooling process after the completion of the second stage of regeneration, and the regenerated absorbent is heated before and after the absorbent with high-temperature reducing gas. It consists of four steps: a step of reducing until the reducing gas concentration becomes the same, and in the regeneration step, the regeneration reactor [1] Continuously recovers heat from the high temperature gas to stabilize absorption and regeneration performance. A method for purifying a high temperature reducing gas (Japanese Patent Application No. 63-27441).

■An absorption process that uses at least four reactors filled with absorbent to absorb and remove sulfur compounds contained in high-temperature reducing gases, a regeneration process that regenerates the absorbent with oxygen-containing gas, and a regeneration process completed. It consists of about 45 steps, including a subsequent cooling step and a reduction step in which the regenerated absorbent is reduced with a high-temperature reducing gas.
High-temperature reducibility characterized by recovering elemental sulfur by supplying one SO, a-containing gas for the reduction reactor, amphiphilic reactor, and cooling reactor to the subsequent sulfur recovery process in the reduction process, regeneration process, and cooling process. Gas purification method (Showa 63 9J1130
(Patent application attached).

[Problem to be solved by the invention] The fixed bed gas purification system proposed in 1- below is as follows:
It consists of a reaction system consisting of absorption, regeneration, and reduction steps, and a downstream sulfur recovery system that processes the SOt gas released from the regeneration system. is a system that suppresses deterioration of absorbent = +
It is necessary to adopt a method at each time.

Factors contributing to the deterioration of the absorbent include thermal deterioration due to temperature rise during 11th generation, accumulation of impurities due to side reactions, and the like.

The absorbent that has completed the absorption process is then transferred to the regeneration process. Then, the reaction shown in equation (5) occurs, and reaction heat is generated. This heat of reaction gradually accumulates in the absorbent, raising its temperature. When the heat resistance limit of the absorbent is exceeded, damage to the carrier, sintering of iron, etc. occur, resulting in a low F absorption capacity.

Therefore, in the above proposal, the two reactors are +iI
＜Continue to introduce gas even after the completion of the ifJ generation process in the column, provide a cooling process to cool the absorbent, and transfer the gas to the middle stage of another regeneration reaction λ1. Efforts have been made to suppress thermal deterioration by introducing part of the system into series (series) operation using two raw reactor towers.

However, in parallel to the two Kawase reactor towers, 0. In the early stage of regeneration when a gas containing gas starts to be introduced, there is a disadvantage that the temperature of the absorbent becomes high due to a rapid exothermic reaction.

In addition, in subsequent research on suppressing side reactions,
In the regeneration process, in addition to the reaction of formula (5), for example, the following (6)
), (7), etc. occur, and a portion of PcS is converted to iron sulfate [Fa, (SQ,)-1.

2PpS +-SOt502→pe, (3Q4), a
ss-am-*m***-m(5)2FetO*+6S
O*To30-'2Fet(SO4)s"""""(7
) This by-product Ft3y (SOJ3) is reduced to SOt again in the next reduction step using the following equations (8) and (9).

3Fct(SO-)s II 0llt →2PcJa
+9SO,II 01120-(8)3Ff! y(
SO4) i+ l0CO-” 2Pe, IO++ 9s
o.
SOt is absorbed by the absorbent and becomes FeS.

)'Q, 0. + 3SO, -+ IOF+, →
3FeS+ 1olIto---(10)
Fc, O, +3SO, -1-10CO → 3PeS+1o
Fe5O4, which reacts in formula (11) (10) and (II), originally reacts in formula (3) and (4) in 11. This should be used to absorb S, and as a result, Fe5Oa, which is effective in absorbing II and S, is lost, leading to a decrease in absorption capacity.

(10), (II) +1. ,Co
is originally a raw material for crude gasification gas and causes energy loss.

Therefore, it is preferable to suppress by-product reactions of Pet(SOa)s such as those in formulas (6) and (7) as much as possible.

To this end, it is necessary to perform regeneration at a higher temperature within the heat resistance limit temperature of the absorbent and to reduce the SO2 concentration as much as possible.

The regeneration gas for the absorbent is a mixture of the treated gas in the sulfur recovery system and air or oxygen-containing gas. The sulfur content (So, It, S.

It is better to reduce Few (gaseous sulfur, etc.) as much as possible
This is preferred in terms of suppressing by-product reactions of js.

The present invention is characterized by an increase in the temperature of the absorbent during regeneration, a decrease in the absorbent capacity due to side reactions, and 1.

This was done with the aim of solving problems such as energy loss of CO.

[Means for Solving the Three Problems] The present invention achieves the second object by reducing the number of reactors filled with absorbent (four towers are used, and reducing the number of reactors from the absorption stage, regeneration RT stage, and reduction stage). In place of the conventional technology, we introduced a new pre-regeneration process before the regeneration process and adopted series regeneration.In addition, we have adopted series regeneration by introducing a new preliminary regeneration process before the regeneration process. This is solved by supplying it to a recovery system.

That is, the present invention provides a method for absorbing and removing sulfur compounds contained in a high-temperature reducing gas using an absorbent, in which at least four reactors filled with an absorbent are used, and the sulfur compounds are absorbed and removed by the absorbent. absorption process, a preliminary regeneration process and regeneration process in which the absorbent is regenerated with oxygen-containing gas, a cooling process after the completion of the regeneration process, and a high-temperature reducibility process for the ambiguous absorbent until the reducing gas concentration before and after the absorbent becomes the same. It consists of the H step of the reduction step of reducing with gas, and the regeneration step and the preliminary (Ii
! 1 life■ process is connected to the series, and the reproduction process starts (
A line is installed to mix the high-temperature gas with the co-gas from the pre-regeneration process, and the regeneration reaction heat is continuously recovered even when switching to the raw process. The present invention relates to a method for purifying a high-temperature reducing gas, characterized by supplying a S0w-containing gas to a sulfur recovery system to recover +11-body sulfur.

F action 1 As mentioned above, immediately add oxygen to the reactor after completing the second absorption step.
When a ta-containing gas is introduced and the regeneration process is started, an exothermic reaction causes a rapid rise in temperature.

In the present invention, the following operation is performed in order to alleviate this exothermic reaction.

The reactor with the west column is always carrying out reduction, absorption, pre-regeneration, regeneration and cooling steps, absorption +7. The reactor that has completed the process is then transferred to the preliminary regeneration process, but since the large V of the gas to be introduced is the IJ gas that has passed through the +rI bioreactor, the amount of gas in the gas during the regeneration is 0. Concentration varies.

That is, as the preliminary regeneration progresses, 0. The concentration increases, and therefore, it is gradually regenerated from a low concentration of 0.
This is advantageous for the absorbent as it results in mild regeneration.

In addition, since we use gas that has gone through one step,
'If the 1q raw raw gas temperature of the T raw process is high, JZ
Temperature can be controlled by introducing cold gas into the bioreactor at a temperature of about 150 to 300°C in one line.

Next, after a certain period of time has elapsed, the pre-regeneration process moves to the +tj raw process, but since the - part of the absorbent has already been regenerated in the pre-regeneration process, the predetermined O2 in the iTf raw process is
There is an advantage that even if a regeneration gas containing a concentration (approximately 1 to 3' 101%) is introduced into the regeneration reactor, a sudden rise in temperature -F does not occur.

In addition, if the temperature of the absorbent is expected to exceed its heat resistance limit, the absorbent can be protected by blowing cold gas that does not contain islands at a temperature of about 150 to 300°C into the affected area. .

That is, a cold gas that does not contain O2 and has a temperature of about 150 to 300 degrees Celsius that has passed through a sulfur recovery system is supplied to a predetermined stage, which is a relatively high temperature section, of a regeneration reactor that is filled with absorbent divided into multiple stages. By controlling the amount of blowing and blowing, the inside of the absorbent can be maintained at a predetermined temperature (for example, 800° C.) or lower, which is extremely effective for extending the life of the absorbent.

In addition, in the present invention, the preliminary regeneration step and the regeneration step are performed in series to perform i[f regeneration, so compared to the conventional two-parallel regeneration system, 0, /'
There is also the advantage that leakage of Fif gas can be prevented.

In the case of a two-term parallel regeneration system, as the regeneration process progresses, 0. Strict control is required because gas is likely to be contained, but in the case of the present invention, since the operation is always in a two-term series, Ot gas in the outlet gas during the cooling process after the end of one round of rolling. will be used in the preliminary regeneration process, and there will always be zero in the gas supplied to the downstream sulfur recovery system.
．． It can be made into a state that does not contain gas.

On the other hand, the present invention is also advantageous over conventional methods in terms of heat balance.

That is, immediately after switching to the preliminary regeneration step after the absorption step is completed, the high temperature side inlet gas of the heat exchanger installed in the L stream of the sulfur recovery system has a low temperature even in the regeneration intermediate stage.

The heat of the high-temperature side gas of this heat exchanger is used to maintain the temperature of the artificial gas for regeneration (about 400 to 500 degrees Celsius), so the temperature should not exceed a predetermined temperature (about 450 to 550 degrees Celsius). It is preferable to keep the temperature stable.

Therefore, in the present invention, the high-temperature gas at the outlet of the regeneration reactor is mixed with the pre-regeneration reaction type gas by the control valve, and the temperature of the artificial gas on the high temperature side of the heat exchanger can be maintained at a predetermined temperature.

The output log gas temperature L9 in each process changes depending on the progress of the F6i regeneration process and 1■ raw balls, but the high temperature gas at the regeneration process outlet is supplied to the preliminary regeneration process exit line! By adjusting It, the high temperature gas temperature of the heat exchanger can be controlled to a constant value, so it is easy to always maintain the regeneration reactor population gas temperature at a predetermined temperature (about 400 to 500°C).

Next, after the regeneration step is completed, the cooling step is started.

At the cooling port, a gas containing 0.0 F under the same conditions (temperature, composition) as the regenerated artificial gas is introduced to recover the heat stored in the absorbent and complete the regeneration.

After passing through a cooling process for a predetermined time, the process moves to a reduction process. As mentioned above, in the regeneration process, the absorbent FcS is
Most of it is converted to Fete, but a part reacts with the 30W gas contained in the regeneration gas and converts into iron sulfate [Fee(S)].
O4), 1 is produced as a by-product. This Fee(SO4)* is decomposed in this reduction step and releases S02 gas. Therefore,
The gas containing SO and gas after the reduction process is supplied to the downstream sulfur recovery system together with the gas after the preliminary birthing process, and is processed.

Note that the gas flow in this reduction process can be carried out in the same direction as the absorption process, but the
Countercurrent flow is more preferred in terms of decomposition.

In addition, in the two sheets of absorption, the absorbent is sulfurized from the upper stage of the gas flow, so in order to suppress the sulfur compounds in the gas to a predetermined concentration (for example, !00 ppm), the sulfidation rate of the absorbent must be (The ratio of Fe to PeS) needs to be kept at about 10 to 50%.

Therefore, the sulfurized portion is partially converted to iron sulfate [Fe-(SO4)ff-1 in the regeneration process, and the SO2 generated by the decomposition is transferred to the iron oxide zone by the reactions of formulas (10) and (I+). In order to prevent m-absorption, it is preferable to use a backflow reduction method in which the reducing gas passes through an iron oxide zone and then a zone containing a relatively large amount of Fet(SOa)s.

The gas whose temperature has been lowered to a predetermined temperature in the heat exchanger upstream of the sulfur recovery system is supplied to the sulfur recovery system, and after recovering the necessary sulfur, '+
It is used for circulation as gas for reciprocity.

As described above, the present invention improves the conventional method for purifying high temperature reducing gas from the viewpoint of absorbent protection and stability performance.

[Example] FIG. 1 is a diagram showing an example of an embodiment of the method of the present invention.

Ite in Figure 1, 1.2.4 and 66 are H, S, CO
A dedusting high-temperature reducing gas line containing sulfur compounds such as No. 3,
3.5-g, 54.57.60 and 63 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 reactor in the regeneration process and reduction process, 17-20 21 is a gas flow path switching valve for mixing the regeneration reactor outlet high temperature gas with the preliminary regeneration reactor outlet gas;
- 24 are reactors filled with the absorbent 25 divided into multiple stages (four stages in this case); 34 - 41 are reactors in which a part of relatively low-temperature oxygen-free circulating gas is subjected to a regeneration process. Flow path switching valves for supplying cooling gas to the 3rd and 4th stages (counting from the 1st side) of the regeneration gas, 55, 58, 61 and 64 are flow paths for purified gas from the reactor in the absorption process. Switching valve, 56.59° 62 and 65 are flow path switching valves for supplying regeneration gas to the reactor in the regeneration process, 47.
49. 51 and 53 are flow path switching valves for supplying oxygen-containing cold gas to the reactor in the pre-6i1 raw temperature stage, 7
0 is a purified gas extraction line, 82 is an rTT raw gas circulation line, 69 is a branch line of gas line 96, which will be described later, 68 is a flow path switching valve, and 71.72 is a line for supplying air or oxygen-containing gas; Flow path switching valve, 67, 81
and 86 are heat exchangers, 73 and A4 are branch lines of the gas line 96, 75 to 78 are branch lines of the gas line 74, and 79 and 8G are mixtures of the gas in line 73 with air or oxygen-containing gas from line 71. Branch line of what was done, 8
3 is a gas line containing a relatively high concentration of sulfur compounds whose temperature has been lowered, 84 is an SO, reduction reactor, 88 is a sulfur condenser, 87
．． 89.91.92 and 95-97 are gas lines, 90
is a sulfur mist separator, g3 is a blower, 98 is a gas flow path switching valve for bypassing the sulfur condenser 88, and 99 and 100 are liquid sulfur (recovered sulfur) lines.

In FIG. 1, a reaction 74 of the same structure is filled with an absorbent 25.
21 to 24 in a reduction step according to formulas (1) and (2), (3
), the absorption process according to formula (4), and the regeneration process according to formula (5) are sequentially switched. If it is a process in which sulfur compounds such as II, S, and CO3 are absorbed and removed using an absorbent and then regenerated according to formula (5), it can be applied regardless of whether it is a fluidized bed type or a moving bed type.In addition, a fixed bed type with four or more Needless to say, it can also be applied to

Further, although the composition and shape of the absorbent are not limited in any way, the case where Fe, 03 is used as the absorbent will be explained here.

The high-temperature reducing gas containing sulfur compounds of Il, S, and COS''5 in line 1 is obtained by, for example, dedusting coal gasification gas to a dust concentration of about 10+++ g/Ns' using a dust collector (not shown). , 5"X depending on the type of coal and gasification conditions, but in addition to dust, there are tens to thousands of pp.
H and S on the floor.

C (contains IS, till, and halogen, etc., and the gas temperature is 250
~500℃, pressure varies depending on the shape of the gasifier, but is usually normal pressure ~25Kg/c*'G.

FIG. 1 shows a state in which a preliminary tQ production process is carried out in a reactor 21, an absorption process is carried out in a reactor 22, a reduction process is carried out in a reactor 23, and a regeneration process is carried out in a reactor 24.

FIG. 2 is a diagram showing an example of a time schedule for absorption, preliminary regeneration, regeneration, cooling, and reduction steps when implementing the present invention.

Here, the absorption, preliminary regeneration, regeneration, cooling and reduction processes and operation of the sulfur recovery system are carried out at approximately the same pressure as the dedusting gasification gas in line 1 (at about normal pressure to 30g/c+s'G). 1 will be explained below based on the time schedule of FIG. 2.

In FIG. 1, the dedusting gasification gas in the line 1 is supplied to the reactor 22 via the flow path switching valve 6, and the sulfur compounds in the gas are normally at 300 to 500°C (3).
It is absorbed and removed by the absorbent 25 according to equation (4), becomes purified gas, and is supplied to a gas turbine (not shown) from the line 70 via the flow path switching valve 58.

During the preliminary regeneration process, the gas that has passed through the regeneration process in the reactor 24 is supplied to the reactor 21 through the line 16, the gas flow switching valve 20, the lines 26 to 30, and the gas flow switching valve 46.
introduced via.

For a while after the transition from absorption to pre-regeneration step (at the same time, pre-regeneration to regeneration step), the outlet gas temperature of the reactor 21 is
Since the temperature of the dedusting gasification gas in line 1 is not much different, or is only a few tens of degrees higher at most, the regeneration inlet gas temperature in the regeneration process is set to be equal to or higher than the temperature of the dedusting gasification gas in line 1. If a high temperature of -1- is desired, it is not practical to maintain the regeneration inlet gas in the regeneration process at a predetermined temperature (400 to 500°C) only by using the downstream heat exchanger 81.

In such a case, in order to maintain the high-temperature side inlet gas of the heat exchanger 81 at a predetermined temperature (450 to 550°C), the required amount of the high-temperature gas at the outlet of the reactor 24 is replaced by the reactor 21 in the preliminary regeneration process. This can be handled by mixing the output L1 gas into the gas line 13 via the gas flow switching valve 17 and introducing it into the heat exchanger 81 via the flow switching valve 9.

The remainder of the high-temperature gas at the outlet of the reactor 24 is transferred from the line 30 to the branch line 79 of the gas line 80 via the flow path switching valve 46 in order to control the regenerated artificial gas in the preliminary regeneration step to a predetermined temperature. It is mixed with the oxygen-containing cold gas sent through valve 47 and introduced into reactor 21 .

As a result, the absorbent 25 in the reactor 21 suddenly rises to a temperature of -1
- It can be protected from temperature rise and also contributes to stabilizing the temperature of the artificial gas on the high temperature side of the heat exchanger 81.

Naturally, the temperature of the log gas output from each reactor 21 and 24 changes depending on the progress of the regeneration process of the reactor 24 and the preliminary regeneration process of the reactor z1, so the temperature of the log gas output from the reactor 24 to the log gas output from the reactor z1 changes. The introduced amount is controlled within a range of about 0 to 70%, and the temperature of the artificial gas on the high temperature side of the heat exchanger 81 is controlled to a predetermined temperature (for example, 500° C.) or higher.

Reaction 'rji23 is in the reduction process, and the reducing gas is
The gas is introduced into the reactor 23 from a gas line 66 branched from the gas line 4 via a flow path switching valve 60 .

The output gas from the reactor 23 containing Sot is combined with the gas after the pre-regeneration treatment via the gas line I5 and the flow path switching valve 11, cooled by the heat exchanger 81, and sent to the sulfur recovery system. A certain amount of sulfur is recovered.

Note that the flow rate of the reducing gas 66 is adjusted to about 0.5 to 5% of the dedusting gasification gas in line 1.

The gas that has passed through the sulfur recovery system is branched to gas lines 73 and 74 via gas line 96.

Regeneration air or oxygen-containing gas is mixed into the gas line 73 through the line 71 and the flow path switching valve 72, and most of the gas (0, concentration: 1~(about 1% Vo))
is sent from line 80 to heat exchanger 81, where it is heated to a predetermined temperature (approximately 400 to 500°C) necessary for regeneration.
The gas is returned to the reactor 24 via the gas line 82 and the gas flow path switching valve 65, and is recycled and regenerated.

When forming a continuous absorption/regeneration cycle as shown in the time schedule of Fig. 2, the reactor 24 has 3,
The absorbent 25 in the fourth stage (viewed from the regeneration gas population side) may be exposed to a relatively high temperature of about 800 to 1000° C. due to the heat of regeneration reaction. In such a case, the temperature of the absorbent in the reactor, where the temperature rises during the regeneration process, should be adjusted to 600-800℃.
In order to cool down to about 00°C, the following operation is performed.

That is, the gas in the gas line 96 that has passed through the sulfur recovery system is
A gas flow switching valve 40° 41 (or 40 or 41).

This gas not only does not contain any Ot, but also has a temperature of about 150 to 300°C, which is considerably lower than the regenerated gas temperature in the rll raw process. There is a sufficient cooling effect on the absorbent 25 in the tiers.

By cooling the absorbent 25 in the high temperature section using this cooling method, it is possible to prevent damage to the carrier in the absorbent 25, sintering of Fe, etc.
It is extremely effective in extending the lifespan of.

In the preliminary regeneration step, oxygen-containing cold gas is supplied to the reactor 21 via the branch line 79 of the gas line 8o and the gas flow path switching valve 47, and the negative part is regenerated here.

Reaction W21 people 2 concentration in logaro gas is reactor 24 people L1
Compared to gas, it is quite low at about 1/4 to 2/4 (, r
Since the temperature rise due to the heat of IT bioreaction becomes slow, the absorbent 25 can be protected from a rapid temperature rise.

The outlet gas of the reactor 21 is introduced into the heat exchanger 81 via the gas line 13 and the gas flow path switching valve 9, and is subjected to a reduction process (sulfur recovery) into the gas 5 in the sulfur recovery system.

When the preliminary regeneration process in the reactor 21 is completed, the process moves to the regeneration process, and the reactor 22 changes to the preliminary regeneration process, the reactor 23 to the absorption process, and the reactor 24 to the reduction process.

At this time, since the reactor 21 has undergone the preliminary regeneration step, it can proceed to the regeneration step without a sudden temperature rise.

As described above, the present invention employs a method of supplying the high-temperature gas after the regeneration reaction to the pre-regeneration high-temperature outlet gas line in an amount according to the gas temperature at that time, and the heat exchanger Fluctuations in the artificial gas temperature on the high-temperature side of 81 can be suppressed and stable operation can be achieved.

By operating the regeneration reactor and pre-regeneration reactor in complete series, the absorbent can be regenerated sufficiently.1-
There is no concern that the () gas in the reactor outlet gas after the completion of 1rtJ production will be mixed into the subsequent sulfur recovery system, and this can be said to be a great advantage.

In addition, if the flow rate of high temperature reducing gas in line 1 decreases under low load or if low sulfur coal is used, (3)
, The amount of FeS in the absorbent produced by the absorption reaction of equation (4) becomes smaller than usual (the heat exhaustion of the regeneration reaction decreases, and it becomes increasingly difficult to balance the heat of the Pi production 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 the sulfur condenser 88 of the sulfur recovery system is partially bypassed.

That is, the gas after the so and i element reactions is transferred to the gas line 85,
This is a method of bypassing the gas line 87 via the heat exchanger 86 to the blower 93 and the artificial gas line 92 via the gas flow path switching valve 98.

At that time, the bypass gas contains sulfur such as II, S, and gaseous sulfur, and these sulfur components are combusted at the inlet of the regeneration reactor or within the reactor, contributing to reheating within the regeneration system. I will do it.

- On the other hand, it is practical to stabilize the absorption performance and regeneration performance even if the amount of processed gas to be purified and the content of sulfur compounds change due to changes in the gasifier load, changes in coal type, etc. strongly requested.

For example, if the amount of high-temperature reducing gas in line 1 containing sulfur compounds such as IItS and cos decreases, or if low-sulfur coal is used, the amount of FeS in the absorbent produced by the absorption reaction will decrease. [Reproduction] The load on the two sheets is reduced.

Therefore, if the regeneration reaction is carried out with the same circulating gas flow as the normal load, the reaction will be completed in a short time, and the heat of the regeneration reaction will decrease as time passes in the regeneration process.

Therefore, the internal temperature of the reactor and the temperature of the I gas during the regeneration process are relatively lower than during normal load, so supplementary heat is required to maintain stable regeneration operation.

A conceivable way to supplement this heat is to supply dedusting high-temperature reducing gas from line 1 containing combustible gases such as CO and IT from outside the system, and use the combustion heat from the combustion reaction between the gas and oxygen. .

However, such use of high-temperature reducing gas consumes Co, H, etc. that should be used downstream of gas purification, and should be avoided as much as possible from the perspective of improving the economic efficiency of the gas purification system. preferable.

Therefore, in order to maintain stable continuous operation even under low load conditions, it is usually possible to reduce the regeneration gas circulation amount and extend the regeneration reaction time.

The regeneration gas circulation line during low load is the same as the normal load described above, but the following measures are taken to protect the blower 93.

That is, normally, when the amount of suction gas in a blower decreases, cooling becomes insufficient and the temperature rises excessively, so it is preferable to keep the amount of suction gas in the blower constant.

Therefore, as the regeneration gas sub-recirculation amount decreases, a part of the gas in the line 92 after sulfur recovery and removal is returned to the front of the sulfur condenser 88 via the line 95 via the flow path switching valve 94, and the blower 93 Ensure that the amount of gas is almost the same as during normal load.

- If it is not possible to replenish the heat inside the regenerated yarn by adjusting the amount of regenerated circulating gas as described in 2., a high-temperature reducing gas is further supplied to the reactor inlet line during the regeneration process, and combustible gas such as C01H7 is combusted. This can be dealt with by reheating using heat.

Although Figure 1 shows an example of a flow in which the absorption, pre-regeneration, regeneration, and reduction operations are performed in countercurrent flow (reverse flow) in the reactor, these operations can also be performed in parallel flow. .

[Effect of the invention] As described below, in the method of the present invention, at least four reactors filled with an absorbent are used, and the five steps of absorption, pre-regeneration, regeneration, cooling, and reduction are performed. By performing complete series operation of the regeneration and cooling processes, abnormal heat accumulation in the absorbent resulting from regeneration reaction heat is alleviated.
Not only can the life of the absorbent be protected, but also by effectively recovering heat from the high-temperature gas at the outlet of the regeneration reactor, it is possible to contribute to stabilizing the temperature of the regeneration reactor population gas.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a flowchart for explaining one embodiment of the method of the present invention, and FIG. 2 is a diagram showing a time schedule of an absorption and regeneration cycle when the present invention is implemented.

Claims (1)

[Claims] In a method of absorbing and removing sulfur compounds contained in a high-temperature reducing gas using 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; A preliminary regeneration step and a regeneration step in which the absorbent is regenerated with an oxygen-containing gas, a cooling step after the regeneration step is completed, and a reduction step in which the regenerated absorbent is reduced with a high-temperature reducing gas until the reducing gas concentration before and after the absorbent becomes the same. The regeneration process and the pre-regeneration process are connected in series, and a line is installed to mix the high-temperature gas at the outlet of the regeneration process with the gas at the outlet of the pre-regeneration process, so that the regeneration reaction heat can be absorbed even when the regeneration process is switched. A method for purifying high-temperature reducing gas, which comprises continuously recovering SO_2-containing gas generated from a preliminary regeneration step, a regeneration step, and a reduction step, and supplying it to a sulfur recovery system to recover elemental sulfur.