JP6033064B2 - CO shift reactor and coal gasification system equipped with the CO shift reactor - Google Patents

Description

The present invention relates to a coal gasification system with a CO shift reactor and the CO shift reactor, in particular, the CO coal gasification gas by conversion into CO ₂ (shift) to separate and recover the CO ₂ It relates to a technique suitable for the above.

As a technology to improve the efficiency of coal-fired thermal power plants, an integrated coal gasification cycle system has been researched and developed. That is, pulverized coal and oxygen are reacted in a gasification furnace to generate a coal gasification gas (hereinafter, abbreviated as “coal gas” as appropriate) containing CO and H ₂ as main components. It is a system that generates electricity by driving a steam turbine by generating steam from combustion exhaust gas of a gas turbine while generating power by burning with a turbine generator.

In the coal gasification process, high concentration of CO (carbon monoxide) is generated. Therefore, a CO shift reaction device is provided, and CO is reacted with water vapor in the presence of the CO shift catalyst by the shift reaction shown by the formula (1). To H ₂ (hydrogen) and CO ₂ (carbon dioxide).
CO + H ₂ O⇔CO ₂ + H ₂ +8.3 kal / gmol (1)
H ₂ produced by the shift reaction is supplied to the gas turbine as fuel, and CO ₂ is efficiently recovered by the CO ₂ separation and recovery device to improve the power generation efficiency of the coal gasification combined power plant. The amount of CO ₂ released is reduced. The CO ₂ separation and recovery device can be configured to absorb and collect CO ₂ in an absorbing solution, for example, but other known methods such as compressing coal gas and condensing and recovering CO ₂ Can be applied.

  By the way, since the shift reaction of the formula (1) is an exothermic reaction, the CO shift catalyst is heated by the shift reaction, and there is a possibility that the heat resistant limit temperature determined from the heat resistance of the catalyst may be exceeded. Therefore, Patent Document 1 proposes a system configuration capable of controlling the CO shift reaction apparatus so that the CO shift catalyst does not exceed the heat resistant limit temperature. That is, according to Patent Document 1, high-pressure steam is mixed with purified coal gas by a high-pressure steam mixer, and the coal gas mixed with high-pressure steam is distributed to a plurality of shift reactors connected in series to perform a CO shift reaction. To do. In particular, the coal gas flowing into the shift reactor on the most upstream side is preheated, and a cooler is provided on the outlet side of each shift reactor to cool the coal gas heated in the shift reaction. In addition, a high temperature shift reactor filled with a shift catalyst having a high activity presentation temperature is arranged on the most upstream side, a low temperature shift reactor filled with a shift catalyst having a low activity presentation temperature is arranged on the most downstream side, A high temperature shift reactor filled with a shift catalyst having a high activity presentation temperature is arranged.

  Further, in Patent Document 1, in order to prevent the CO shift catalyst from exceeding the heat resistant limit temperature due to the CO concentration fluctuation of the coal gas flowing into the most upstream high temperature shift reactor, a part of the coal gas is steam mixer, preheated. And a bypass line for bypassing the uppermost upstream high temperature shift reactor and introducing it to the next stage, for example, a high temperature shift reactor. As a result, the amount of main gas flowing into the most upstream high temperature shift reactor and the amount of gas to be bypassed are adjusted so that the gas temperature at the outlet of the most upstream high temperature shift reactor is lower than the heat resistant limit temperature of the CO shift catalyst. The temperature is kept low and higher than the activity presentation temperature. Furthermore, if necessary, a recycle gas line is provided for boosting the coal gas having a low CO concentration flowing out from the most downstream low temperature shift reactor and returning it to the upstream side of the steam mixer of the most upstream high temperature shift reactor, In addition to the adjustment of the amount of gas flowing into the uppermost upstream high temperature shift reactor and the amount of bypass gas, the temperature of the CO shift catalyst can be controlled by adjusting the amount of recycle gas.

JP 2012-21144 A

  However, in the technique described in Patent Document 1, the temperature distribution in the gas flow direction in the CO shift catalyst layer of the high temperature shift reactor changes as the amount of gas flowing into the uppermost high temperature shift reactor is adjusted. I don't care about what to do. That is, when the CO concentration of coal gas increases (for example, 50 vol%), the catalyst temperature may exceed the heat-resistant limit temperature (for example, 480 ° C.) due to the CO shift reaction. Therefore, by bypassing the uppermost high-temperature shift reactor and flowing coal gas to the downstream-side shift reactor, the amount of main gas introduced into the uppermost high-temperature shift reactor is reduced, thereby reducing the CO shift reaction. The calorific value is reduced to lower the gas temperature at the outlet.

  However, when the amount of main gas flowing through the uppermost high-temperature shift reactor is reduced, the space velocity is reduced, so that the shift reaction per unit length of the CO shift catalyst layer is promoted. Therefore, there is a possibility that the highest temperature point moves upstream and the possibility of exceeding the heat resistant limit temperature is increased. Moreover, if the amount of main gas circulated to the most upstream high temperature shift reactor is reduced based on the measured temperature of the thermocouple installed at the outlet of the CO shift catalyst layer, the temperature in the most downstream portion is drastically lowered. Then, in response to this, the amount of main gas flowing through the most upstream high-temperature shift reactor is increased, and as a result, the flying speed increases and the highest temperature point moves downstream. However, since there is a delay in heat transfer, the maximum catalyst temperature of the CO shift catalyst layer becomes higher than before the bypass control, and the control of the main gas amount and the bypass gas amount may cause hunting. Such a hunting phenomenon frequently occurs when the bypass control operation starts or when the load increases.

  The problem to be solved by the present invention is to stably maintain the temperature of the CO shift reaction catalyst in the uppermost high temperature shift reactor below the heat-resistant limit temperature in response to CO concentration fluctuation and flow rate fluctuation in coal gas. There is.

  In order to solve the above-described problem, the first aspect of the present invention includes a high-pressure steam mixer that mixes high-pressure steam with coal gas supplied by gasifying coal, and coal gas in which the high-pressure steam is mixed. A plurality of shift reactors connected in series including the uppermost high temperature shift reactor filled with a CO shift catalyst having a high activity presentation temperature, and coal flowing into the high temperature shift reactor via the high pressure steam mixer A main gas amount adjusting valve for adjusting the gas amount of the gas, and a bypass line for branching from the upstream side of the main gas amount adjusting valve to bypass the high temperature shift reactor and introduce coal gas into the downstream shift reactor And a bypass gas amount control valve for adjusting the amount of bypass gas provided in the bypass line, in the CO shift catalyst layer of the high temperature shift reactor in the uppermost stream A plurality of temperature sensors arranged along the gas flow direction, and the main gas amount control valve and the bypass gas amount based on the temperature in the CO shift catalyst layer by inputting measured temperatures of the plurality of temperature sensors And a control device that controls the catalyst temperature to a set temperature by controlling the control valve, and the control device compares the measured temperatures of the plurality of temperature sensors so as to maintain the maximum catalyst temperature at the set temperature. The main gas amount adjusting valve and the bypass gas amount adjusting valve are controlled.

  Further, according to a second aspect of the present invention, in the first aspect, the plurality of temperature sensors arranged in the CO shift catalyst layer of the most upstream high temperature shift reactor are an inlet portion and a central portion of the CO shift catalyst layer. It is preferable that the number is at least 3 so that the temperature of the outlet can be measured. In this case, the control device selects the temperature sensor showing the maximum temperature and uses it for temperature control of the CO shift catalyst layer.

  Further, according to a third aspect of the present invention, in the first or second aspect, when the maximum catalyst temperature of the most upstream high temperature shift reactor rises above the set temperature, the control device is configured to set the set range. After the threshold value set in the middle of the temperature limit and the heat-resistant limit temperature (alarm set value) is exceeded, the opening degree of the bypass gas amount adjusting valve is instantaneously (temporarily) opened within a range of 5 to 10% of full opening Further, it is possible to perform control for returning the opening degree of the bypass gas amount adjusting valve to the original position.

  In the case of the third aspect, when the maximum catalyst temperature of the most upstream high temperature shift reactor rises exceeding the set range, the opening degree with respect to the main gas amount control valve and the bypass gas amount control valve The main gas amount control valve is fixed by narrowing it from a 100% opening to a predetermined opening, and the bypass gas amount adjusting valve has a constant rate from 0% according to the opening command. Can be controlled to increase the opening.

  In the third aspect, the rate of increase of the opening degree of the bypass gas amount adjusting valve is the amount of coal gas flowing through the main gas amount adjusting valve when the opening degree of the bypass gas amount adjusting valve is 100%. The opening degree of the bypass gas amount adjusting valve can be determined so that the bypass flow amount flowing through the bypass gas amount adjusting valve is substantially the same at 50% of the total flow rate of the coal gas.

Further, the coal gasification system of the present invention includes a CO shift reaction device that converts carbon monoxide (CO) in coal gas supplied by gasifying coal into carbon dioxide (CO ₂ ), and the CO shift reaction device. in is configured to converted the CO ₂ and a CO ₂ separation and recovery device for recovering and separating, as the CO shift reactor, alone CO shift reactor of the first to third any aspect Or in combination.

  According to the present invention, the temperature of the CO shift reaction catalyst in the uppermost high-temperature shift reactor can be stably kept below the heat-resistant limit temperature in response to CO concentration fluctuations and flow rate fluctuations in coal gas.

It is a block block diagram of the coal gasification system of one Embodiment of this invention. It is a system | strain block diagram of Example 1 of the CO shift reaction apparatus of this invention. It is a figure explaining the solution subject which concerns on the characteristic structure of Example 1 of the CO shift reaction apparatus of this invention. It is a figure explaining the relevant control of the opening degree of the main gas amount control valve and bypass gas amount control valve of Example 1 of this invention. It is a figure explaining an example of the advance control which lowers | hangs the temperature of the CO shift catalyst layer of Example 1 of this invention rapidly. It is a system | strain block diagram of Example 2 of the CO shift reaction apparatus of this invention.

Hereinafter, a coal gasification system including a CO ₂ separation and recovery apparatus equipped with a CO shift reaction apparatus of the present invention will be described based on embodiments. As shown in FIG. 1, a coal gasification system 100 according to an embodiment of the present invention is configured such that coal 101 is sent to a coal pressurized supply facility 102 and pulverized, and pressurized pulverized coal is supplied to a gasifier 103. Supplied. The pulverized coal is jetted into the furnace together with oxygen supplied from the air separation facility 104 from a nozzle provided on the pressurized gasification furnace 103, and CO and H _{2 are} generated by a part of the combustion heat of the pulverized coal. It is gasified to coal gas containing as a main component. The coal gas is heat-recovered by the gas heat exchanger 105 and guided to the dedusting / desulfurization facility 106 to remove fly ash and sulfur content in the coal gas. The coal gas from which fly ash and sulfur have been removed is further refined in the gas purification facility 107 and introduced into the CO shift reactor 108.

In the CO shift reactor 108 is fed high pressure steam _(H 2 O) from the high-pressure steam equipment 109, and CO ₂ by the reaction CO and of _{H 2} O in coal gas by CO-shift reaction of formula (1) described above It is converted to H ₂ (shift). The coal gas shifted by the CO shift reactor 108 is guided to the absorption tower 110, and CO ₂ is absorbed by the absorption liquid and separated from the coal gas. When the CO ₂ is separated, the coal gas becomes almost H ₂ and is supplied to the gas turbine 111 as fuel. The absorption liquid that has absorbed CO ₂ by the absorption tower 110 is guided to the absorption liquid regenerator 112, and CO ₂ in the absorption liquid is separated and recovered to regenerate the absorption liquid. The regenerated absorption liquid is circulated to the absorption tower 110 by the absorption liquid pump 113. In this way, the coal gasification system 100 of this embodiment continuously gasifies coal to shift CO to H ₂ and CO ₂ , and separates and recovers CO ₂ to improve the efficiency of the gas turbine. CO ₂ emission is reduced.

  Next, with reference to FIG. 2, Example 1 of the system configuration of the CO shift reactor 108 will be described in detail. The coal gas is preheated by the No. 1 preheater 106a, and the sulfur content in the coal gas which is a poisoning component of the CO shift catalyst is removed by the desulfurizer 106b. Further, nitrogen gas can be supplied to the upstream pipe line of the No. 1 preheater 106 a through the purge nitrogen gas supply valve 17.

The CO shift reactor 108 includes a high-pressure steam mixer 3, a No. 2 preheater 4, an uppermost high-temperature shift reactor 5, a No. 1 shift gas cooler 6, a second-stage high-temperature shift reactor 7, The No. 2 shift gas cooler 8, the third stage low temperature shift reactor 9, and the No. 3 shift gas cooler 10 are sequentially connected in series. The No. 3 shift gas cooler 10 supercools the coal gas to condense the water vapor, guides it to the knockout drum 11 and removes the condensed water, and then absorbs CO ₂ into the absorption liquid in the absorption tower 110 shown in FIG. Separated and recovered.

  The high pressure steam mixer 3 is supplied with coal gas from the desulfurizer 106b through the coal gas line 20 and the main gas amount control valve 18a. Moreover, it branches from the upstream side of the main gas amount control valve 18a, bypasses the high pressure steam mixer 3, No. 2 preheater 4, and the uppermost high temperature shift reactor 5, so that the coal gas is supplied to the high temperature shift reactor 5. A bypass line 21 to be introduced into the outlet side pipe line is provided. A bypass gas amount adjusting valve 18b is interposed in the bypass line 21. In addition, the amount of coal gas flowing through the No. 1 shift gas cooler 6 is adjusted to a pipeline connecting the outlet of the high temperature shift reactor 5 and the No. 1 shift gas cooler 6, so that the No. 1 shift gas cooler 6 A temperature control valve 12 for controlling the temperature of the coal gas on the outlet side of the engine is interposed. Similarly, a temperature control valve 13 for controlling the temperature of coal gas on the outlet side of the No. 2 shift gas cooler 8 is interposed in a pipe line connecting the high temperature shift reactor 7 and the No. 2 shift gas cooler 8. Yes.

  A recycle gas line 19 is provided for extracting coal gas from the downstream side of the knockout drum 11 by the recycle gas compressor 14 and recycling it to the inflow side of the high-pressure steam mixer 3. A recycle gas amount control valve 15 is interposed in the recycle gas line 19. As a result, the CO concentration of the coal gas flowing into the high temperature shift reactor 5 can be diluted. A bypass line 22 that bypasses the entire CO shift reactor 108 and releases coal gas from the downstream side of the desulfurizer 106 b to the downstream side of the knockout drum 11 is provided. A bypass valve 16 is interposed in the bypass line 22.

  A flow meter 24a for measuring the flow rate of coal gas flowing in the upstream line of the No. 1 preheater 106a, a flow meter 24b for measuring the main gas amount of coal gas flowing into the high temperature shift reactor 5, and a high temperature shift A flow meter 24c that measures the amount of bypass gas that flows through the bypass line 21 of the reactor 5 and a flow meter 24d that measures the amount of bypass gas that flows through the bypass line 22 that bypasses the entire CO shift reactor 108 are provided. It has been. The flow rates measured by these flow meters 24 a to 24 d are input to the control device 25.

  In addition, temperature sensors 23a and 23b using, for example, thermocouples that measure the temperature of the CO shift catalyst layer at the inlet, center, and outlet in the CO shift catalyst layer of the high temperature shift reactor 5 of the present embodiment, 23c is installed. Further, a temperature sensor 23 d for measuring the temperature of coal gas flowing out from the CO shift catalyst layer of the high temperature shift reactor 5 is installed. The temperatures measured by these temperature sensors 23 a to 23 d are input to the control device 25. The control device 25 includes a main gas amount adjusting valve 18a, a bypass gas amount adjusting valve 18b, temperature adjusting valves 12, 13, a recycle gas amount adjusting valve 15, a bypass valve 16, and a purge nitrogen gas supply valve 17. These are controlled by the control device 25, respectively.

  Operation | movement of the CO shift reaction apparatus 108 of Example 1 comprised in this way is demonstrated. The coal gas flowing out from the desulfurizer 106b flows into the high-pressure steam mixer 3 through the main gas amount control valve 18a. At this time, the flow rate of the coal gas is controlled by adjusting the opening of the main gas amount adjusting valve 18a by the control device 25 based on the measured flow rate of the flow meter 24b. Moreover, although not shown in figure, the high pressure steam corresponding to the shift reaction of said Formula (1) is supplied to the steam mixer 3, and is mixed. Next, no. 2 The pre-heater 4 preheats to the CO shift catalyst activity presentation temperature (for example, ≈300 ° C.) and flows into the uppermost high-temperature shift reactor 5, whereby the CO shift reaction proceeds.

The shifted coal gas flowing out from the high temperature shift reactor 5 is cooled by the No. 1 shift gas cooler 6 and then flows into the second stage high temperature shift reactor 7 to proceed the shift reaction. The shifted coal gas flowing out from the high temperature shift reactor 7 is cooled by the No. 2 shift gas cooler 8, and then flows into the low temperature shift reactor 9, where the shift reaction further proceeds. The shifted coal gas flowing out from the low temperature shift reactor 9 is no. It is cooled by the 3-shift gas cooler 10, and excess water vapor is condensed, and the generated condensed water is removed by the knockout drum 11. The coal gas that has passed through the knockout drum 11 is introduced into the absorption tower 110 shown in FIG. 1, and CO ₂ is absorbed and separated.

  By the way, since coal gas has a very high CO concentration (for example, 50 vol%), the reaction temperature due to the shift reaction is large, so that the catalyst temperature in the uppermost high temperature shift reactor 5 is the heat resistant limit temperature (for example, 480 ° C.). If the shift catalyst is damaged, the stable operation of the CO shift reactor 108 and thus the coal gasification system is impaired.

  Therefore, conventionally, a bypass line 21 is provided in the most upstream high temperature shift reactor 5 and a recycle gas line 19 for diluting the CO concentration of coal gas flowing into the high temperature shift reactor 5 is provided. That is, the bypass line 21 bypasses the high temperature shift reactor 5 from the coal gas line 20 between the desulfurizer 2 and the high-pressure steam mixer 3 so as to guide the coal gas to the outlet side of the high temperature shift reactor 5. . The bypass flow rate of the coal gas flowing through the bypass line 21 is adjusted by the control device 25 by controlling the bypass gas flow rate adjusting valve 18b. Further, the flow rate of the coal gas to be circulated to the high temperature shift reactor 5 is adjusted by controlling the main gas amount adjusting valve 18 a by the control device 25. Specifically, when the temperature of the CO shift catalyst layer of the high temperature shift reactor 5 exceeds a preset temperature, the amount of coal gas flowing into the high temperature shift reactor 5 is limited to suppress the exothermic reaction. Then, the temperature of the CO shift catalyst layer is maintained at the set temperature.

  On the other hand, the coal gas bypassing the high temperature shift reactor 5 flows into the second stage high temperature shift reactor 7 and the shift reaction proceeds. However, in the second stage high temperature shift reactor 7, the CO concentration is lowered, and even if the reaction is performed in the high temperature shift reactor 5, it is cooled by the No. 1 shift gas cooler 6. Even if it generates heat, the temperature does not rise enough to exceed the preset temperature. Further, when the increase in the catalyst temperature of the high temperature shift reactor 5 cannot be absorbed by the bypass control by the bypass line 21, the bypass valve 16 is opened to release the coal gas, and the recycle gas line 19 is supplied from the recycle gas compressor 14. By recycling the coal gas shifted through, the CO concentration of the coal gas at the inlet of the high temperature shift reactor 5 is diluted. Such temperature control that bypasses the conventional high temperature shift reactor 5 is an indispensable method for the CO shift reaction apparatus.

Here, the characteristic structure of the CO shift reaction apparatus 108 of Example 1 is demonstrated. For this purpose, a solution problem related to the characteristic configuration will be described with reference to FIG.
(1) Problems associated with bypassing the shift reactor When the opening degree of the main gas amount adjusting valve 18a is reduced and the opening degree of the bypass gas amount adjusting valve 18b is opened, the coal gas flowing into the high temperature shift reactor 5 is reduced. Main gas volume is reduced. With the decrease in the main gas amount, the calorific value of the CO shift catalyst of the high temperature shift reactor 5 decreases, and the temperature of the coal gas flowing out from the high temperature shift reactor 5 decreases. However, since the SV of the shift catalyst decreases as the gas amount decreases, the CO shift catalyst has a sufficient performance (activity). As a result, the maximum temperature point in the CO shift catalyst layer moves to the upstream side in the gas flow direction of the CO shift catalyst layer (from point A to point B in FIG. 3A). The temperature distribution in the gas flow direction at this time changes from a dotted line 31 to a profile indicated by a solid line 32 in the figure. In addition, as the catalytic activity increases due to the decrease in SV, the maximum catalyst temperature rises, resulting in inconvenience that the heat resistant limit temperature may be exceeded.

(2) Problems due to the position of the temperature control point of the CO shift catalyst The temperature control of the CO shift catalyst of the high temperature shift reactor 5 has conventionally been set in advance by setting the measured temperature generally measured by the temperature sensor 23d of FIG. The main gas amount adjusting valve 18a and the bypass gas amount adjusting valve 18b are controlled so as to maintain the temperature. That is, since the temperature measurement point is one point of the temperature sensor 23d, as described in the above (1), when the highest temperature point in the CO shift catalyst layer moves upstream, the temperature sensor that is the temperature measurement point. The measured temperature of 23d rapidly decreases (from point A to point C in FIG. 3A). As a result, since the control device 25 issues a command to open the main gas amount adjusting valve 18a and close the bypass gas amount adjusting valve 18b, the main gas amount of the coal gas flowing through the high temperature shift reactor 5 increases, The shift reaction heat increases and the temperature of the CO shift catalyst layer rises. At this time, as shown in FIG. 3B, the maximum temperature point also moves upstream in the gas flow direction (from the dotted line 33 to the solid line 34), and the temperature measured by the temperature sensor 23d rises rapidly (FIG. 3 ( b) from point D to point E).

  In addition, due to the time delay of heat transfer, the maximum catalyst temperature may be higher than before the bypass control, and may exceed the heat resistance limit temperature. Therefore, conversely, the control device 25 issues a command for closing the main gas amount adjusting valve 18a and opening the bypass gas amount adjusting valve 18b. By this series of controls, the temperature distribution of the CO shift catalyst layer and the maximum catalyst temperature are changed in the high temperature shift reactor 5, and the amount of main gas flowing into the high temperature shift reactor 5 and the amount of bypass gas in the bypass line 21 are also changed. As a result, a hunting phenomenon occurs in which the temperature of the CO shift catalyst layer cannot be controlled. In general, the temperature of the CO shift catalyst layer also causes an emergency stop of the coal gasification system including the CO shift reaction device from the viewpoint of catalyst protection. In particular, the above-described hunting phenomenon is presumed to occur frequently when bypass control of the high temperature shift reactor 5 is started or when the load is increased, and becomes a factor that hinders stable operation of the apparatus.

  In order to deal with these problems, the first embodiment has the following characteristic configuration. First, the temperature sensors 23a, 23b, and 23c are dispersedly arranged in the CO shift catalyst layer of the most upstream high-temperature shift reactor 5 at three locations of the inlet portion, the central portion, and the outlet portion along the gas flow direction. And In addition, the number of dispersion | distribution arrangement | positioning of a temperature sensor is not restricted to three, Three or more can be arrange | positioned according to the length of the gas flow direction of a CO shift catalyst layer, and a cross-sectional area. Further, in order to measure the temperature of the coal gas at the outlet of the high temperature shift reactor 5, the temperature sensor 23d is installed in the space of the reactor on the downstream end side of the CO shift catalyst layer as in the conventional case. .

  According to the first embodiment, the measured temperatures of the temperature sensors 23a, 23b, and 23c in the CO shift catalyst layer are taken into the control device 25, and the control device 25 sets any one of the temperature sensors 23a to 23c indicating the highest measured temperature to 1 Select one. Then, when the temperature measured by the selected temperature sensor 23 is set to the maximum catalyst temperature and the maximum catalyst temperature is maintained at a preset temperature, for example, when the temperature approaches or exceeds the heat limit temperature, the amount of main gas The control valve 18a is closed and the bypass gas amount control valve 18b is opened.

  With reference to FIG. 4, the related control of the opening degree of the main gas amount adjusting valve 18a and the bypass gas amount adjusting valve 18b of the first embodiment will be described. Among the temperature sensors 23a to 23c, the measured temperature of the temperature sensor indicating the highest measured temperature is set as the highest catalyst temperature of the CO shift catalyst layer. When the maximum catalyst temperature of the CO shift catalyst layer approaches or exceeds the heat-resistant limit temperature, the control device 25 sends a command to the main gas amount control valve 18a to set the opening degree from the fully open position (example in FIG. 4). Then, the aperture is reduced to 70% and the opening is maintained. This is to give flow resistance to the coal gas flowing through the high temperature shift reactor 5 to facilitate the flow of the coal gas to the bypass line 21 and to easily adjust the amount of the bypass gas.

  On the other hand, the control device 25 sends an opening degree command (0 to 100%) to the bypass gas amount adjusting valve 18b according to the degree to which the maximum temperature of the CO shift catalyst layer exceeds the set temperature. The bypass gas amount adjusting valve 18b is configured to open from an opening degree 0 to a set opening degree (87% opening degree in the example of FIG. 4). Here, the opening degree of the main gas amount adjusting valve 18a and the bypass gas amount adjusting valve 18b is obtained in advance by obtaining the relationship between the opening degree of the both and the flow gas amount. And the flow rate ratio of the bypass gas amount is set to approximately 1: 1. In this way, by setting the opening commands of the main gas amount adjusting valve 18a and the bypass gas amount adjusting valve 18b, the control device 25 allows the bypass gas according to the degree to which the maximum temperature of the CO shift catalyst layer exceeds the set temperature. The main gas amount can be adjusted and the bypass gas amount can be adjusted only by controlling the opening command of the amount adjusting valve 18b. That is, the opening control of the main gas amount adjusting valve 18a and the bypass gas amount adjusting valve 18b of the first embodiment is performed by a series of programs set so as to correlate the opening amounts of both the adjusting valves.

  By the way, even if the opening control of the main gas amount control valve 18a and the bypass gas amount control valve 18b of the first embodiment shown in FIG. The maximum measured temperature may exceed the heat resistance limit temperature. In such a case, it is desirable to perform advance control that temporarily increases the amount of bypass gas in advance, as shown in FIG. 5, while performing the related control shown in FIG. That is, the threshold value (475 ° C. in the illustrated example) is set between the set temperature (470 ° C. in the illustrated example) and the heat resistant limit temperature (480 ° C. in the illustrated example). When the measured maximum temperature exceeds the threshold value, the opening degree of the bypass gas amount adjusting valve 18b is temporarily increased by a set opening degree (for example, 0 to 10% of full opening, preferably 5 to 10%). To quickly return to the original position. Thereby, the temperature of the CO shift catalyst layer can be rapidly decreased, and the temperature increase of the CO shift catalyst layer can be suppressed.

  In FIG. 6, the system block diagram of Example 2 of the CO shift reaction apparatus 108 of this invention is shown. The difference between the second embodiment and the first embodiment is that the bypass gas 16 of the first embodiment is opened to release the coal gas, and the coal gas shifted from the recycle gas compressor 14 through the recycle gas line 19 is recycled. Thus, the line for diluting the CO concentration of the coal gas at the inlet of the high temperature shift reactor 5 is omitted. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

As described above, according to the present invention, in order to efficiently separate and recover CO ₂ from coal gasification gas containing high-concentration CO, CO that converts CO in coal gasification gas to CO ₂ is used. In the shift reaction apparatus, the CO shift catalyst is protected from the temperature rise due to the shift reaction heat, and stable operation becomes possible. Further, in all operating states including when the CO shift reactor bypass control operation is started or when the load is increased, the CO in the high temperature shift reactor on the most upstream side is made to correspond to the CO concentration fluctuation and the flow fluctuation in the coal gas. The temperature of the shift catalyst can be stably maintained below the heat resistant limit temperature.

3 High-pressure steam mixer 4 No. 2 Preheater 5 High temperature shift reactor 6 No. 1 shift gas cooler 7 High temperature shift reactor 8 No. 2 shift gas cooler 9 Low temperature shift reactor 10 No. 3 shift gas cooler 11 Knockout drum 12 Temperature control valve 13 Temperature control valve 14 Recycle Gas Compressor 15 Recycle Gas Amount Control Valve 16 Bypass Valve 17 Purge Nitrogen Gas Supply Valve 18a Main Gas Amount Control Valve 18b Bypass Gas Amount Control Valve 19 Recycle Gas Line 20 Coal Gas Line 21 Bypass Line 22 Bypass Lines 23a-d Temperature sensor 24a-d Flow meter 25 Control device

Claims (10)

  A high-pressure steam mixer that mixes high-pressure steam with coal gas supplied by gasifying coal, and a high-temperature uppermost stream filled with a CO shift catalyst having a high activity presentation temperature into which the coal gas mixed with the high-pressure steam is introduced. A plurality of shift reactors connected in series including a shift reactor; a main gas amount control valve for adjusting the amount of coal gas flowing into the high temperature shift reactor via the high-pressure steam mixer; and the main gas A bypass line for branching from the upstream side of the quantity control valve to bypass the high temperature shift reactor and introducing coal gas into the downstream shift reactor, and a bypass gas quantity provided in the bypass line for adjusting the bypass gas quantity And a plurality of temperature sensors disposed along the gas flow direction in the CO shift catalyst layer of the uppermost high temperature shift reactor. Then, the measured temperatures of the plurality of temperature sensors are input and the main gas amount adjusting valve and the bypass gas amount adjusting valve are controlled based on the temperature in the CO shift catalyst layer to control the catalyst temperature to the set temperature. And a control device that compares the measured temperatures of the plurality of temperature sensors and maintains the maximum catalyst temperature at the set temperature so as to maintain the maximum catalyst temperature and the bypass gas amount control valve. CO shift reaction apparatus characterized by controlling. The CO shift reactor according to claim 1,
The plurality of temperature sensors arranged in the CO shift catalyst layer of the most upstream high temperature shift reactor are arranged at least at three locations of an inlet portion, a central portion, and an outlet portion of the CO shift catalyst layer,
The control device controls the main gas amount adjusting valve and the bypass gas amount adjusting valve with the measured temperature of the temperature sensor showing the highest measured temperature among the temperature sensors as the highest catalyst temperature. CO shift reactor. In the CO shift reaction apparatus according to claim 1 or 2,
When the maximum catalyst temperature of the most upstream high temperature shift reactor has exceeded the set temperature, the control device has exceeded a threshold value set between the set temperature and the heat-resistant temperature (alarm set value). Then, after the opening degree of the bypass gas amount adjusting valve is instantaneously (temporarily) opened within a range of 5 to 10% of the fully opened state, the opening degree of the bypass gas amount adjusting valve is controlled to return to the original position. Characteristic CO shift reactor. The CO shift reactor according to claim 3,
The control device opens the main gas amount control valve and the bypass gas amount control valve when the maximum catalyst temperature of the CO shift catalyst layer of the most upstream high temperature shift reactor rises above the set temperature. Output a degree command,
The opening degree command is fixed by narrowing the main gas amount adjustment valve from a degree of opening of 100% to a predetermined opening degree, and the bypass gas amount adjusting valve is set at a constant rate from 0% to the degree of opening instruction. A CO shift reaction apparatus characterized in that the command is an instruction to increase the opening. The CO shift reactor according to claim 4,
The rate of increasing the opening degree of the bypass gas amount control valve is the amount of coal gas flowing through the main gas amount control valve and the bypass gas amount control valve when the opening amount of the bypass gas amount control valve is 100%. The CO shift reaction apparatus is characterized in that the amount of bypass gas flowing through the gas is set to be approximately the same at 50% of the total amount of the coal gas. A CO shift reactor for converting coal to carbon monoxide in the coal gas to be supplied to the gasification (CO) to carbon dioxide (CO _2), and to separate the CO ₂ converted in the CO shift reactor A CO ₂ separation and recovery device for recovery, wherein the CO shift reaction device is a high pressure steam mixer that mixes high pressure steam with the coal gas, and a high activity presentation temperature into which the coal gas mixed with the high pressure steam flows. A plurality of shift reactors connected in series including an uppermost high temperature shift reactor filled with a CO shift catalyst, and the amount of coal gas flowing into the high temperature shift reactor via the high-pressure steam mixer is adjusted. A main gas amount adjusting valve, a bypass line branched from the upstream side of the main gas amount adjusting valve, bypassing the high temperature shift reactor and introducing coal gas into the downstream shift reactor, In a coal gasification system comprising a bypass gas amount adjusting valve that is provided in the bypass line and adjusts the amount of bypass gas,
A plurality of temperature sensors arranged along the gas flow direction in the CO shift catalyst layer of the high temperature shift reactor of the uppermost stream, and the measured temperatures of the plurality of temperature sensors are input to enter the CO shift catalyst layer A control device that controls the main gas amount adjusting valve and the bypass gas amount adjusting valve based on temperature to control the catalyst temperature to a set temperature, and the control device is configured to control measured temperatures of the plurality of temperature sensors. The coal gasification system is characterized in that the main gas amount control valve and the bypass gas amount control valve are controlled so that the maximum catalyst temperature is maintained at the set temperature in comparison. The coal gasification system according to claim 6,
The plurality of temperature sensors arranged in the CO shift catalyst layer of the most upstream high temperature shift reactor are arranged at least at three locations of an inlet portion, a central portion, and an outlet portion of the CO shift catalyst layer,
The control device controls the main gas amount adjusting valve and the bypass gas amount adjusting valve with the measured temperature of the temperature sensor showing the highest measured temperature among the temperature sensors as the highest catalyst temperature. Coal gasification system. In the coal gasification system according to claim 6 or 7,
When the maximum catalyst temperature of the most upstream high temperature shift reactor has exceeded the set temperature, the control device has exceeded a threshold value set between the set temperature and the heat-resistant temperature (alarm set value). Then, after the opening degree of the bypass gas amount adjusting valve is instantaneously opened within a range of 5 to 10% of the full opening, the coal is controlled to return the opening degree of the bypass gas amount adjusting valve to the original position. Gasification system. The coal gasification system according to claim 8,
The control device opens the main gas amount control valve and the bypass gas amount control valve when the maximum catalyst temperature of the CO shift catalyst layer of the most upstream high temperature shift reactor rises above the set temperature. Output a degree command,
The opening degree command is fixed by narrowing the main gas amount adjustment valve from a degree of opening of 100% to a predetermined opening degree, and the bypass gas amount adjusting valve is set at a constant rate from 0% to the degree of opening instruction. A coal gasification system characterized by a command to increase the opening degree. The coal gasification system according to claim 9,
The rate of increasing the opening degree of the bypass gas amount control valve is the amount of coal gas flowing through the main gas amount control valve and the bypass gas amount control valve when the opening amount of the bypass gas amount control valve is 100%. The coal gasification system is characterized in that the amount of bypass gas flowing through the coal gas is set to be substantially the same at 50% with respect to the total amount of the coal gas.

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