JP5535587B2 - Gasification system and operation method thereof - Google Patents

Description

  The present invention relates to a gasification system and an operation method thereof.

As a countermeasure against global warming, carbon contained in carbon-based fuel can be recovered even for a carbon-based fuel gasification system that produces a mixed gas of hydrogen (H ₂ ) and carbon monoxide (CO). It has been demanded. The main components of the product gas obtained by gasifying carbon-based fuel are carbon monoxide and hydrogen. When this carbon monoxide is removed in order to remove carbon contained in the product gas, the amount of heat generated by the product gas is greatly reduced.

For this reason, using the shift reaction shown in the following reaction formula (1), carbon monoxide is reacted with water vapor (H ₂ O) to form hydrogen and carbon dioxide (CO ₂ ), and carbon dioxide is removed from the product gas. Therefore, a method of recovering carbon contained in the generated gas while minimizing a decrease in the calorific value of the generated gas is generally used.

CO + H ₂ O → CO ₂ + H ₂ (1)
For example, Patent Document 1 discloses a carbonization gasification system including such a shift reaction process. In this system, a shift reactor (shift converter) for proceeding with the shift reaction is installed, and water vapor is supplied to this equipment. That is, in Patent Document 1, for the purpose of providing a CO ₂ -removed coal gasification combined power generation system capable of removing hydrogen chloride gas contained in coal gasification gas and increasing CO conversion to recover carbon dioxide gas, In a coal gasification combined power generation system that uses a gasification furnace to gasify a fuel such as coal to generate high-temperature coal gasification gas and use it for power generation, the coal gasification gas from the gasification furnace is converted into a wet scrubber. After removing hydrogen chloride contained in the gas, the gas is introduced into the shift converter, steam is supplied to the shift converter to convert CO contained in the gas into CO ₂ , and then the coal gasification gas is converted into decarbonized gas. CO ₂ removal coal gasification combined cycle system, characterized in that the removal of CO ₂ have been disclosed through the device.

  Patent Document 2 discloses a method in which a shift reactor is not required by supplying steam or coal bed gas to a gasification furnace and advancing the shift reaction in the gasification furnace. That is, Patent Document 2 provides a production apparatus capable of producing a mixed gas of hydrogen and carbon monoxide by reacting coal and coal bed gas under high pressure conditions, and a fuel / electric power co-production plant including the same. For this purpose, an apparatus for producing a mixed gas of hydrogen and carbon monoxide in a gasifier using a carbonaceous fuel and a coal bed gas mainly composed of methane as raw materials, the gas flowing in one direction And a supply system for supplying the carbon-based fuel, the coal bed gas, and the oxidant to the upstream region so that partial oxidation of the carbon-based fuel and the coal bed gas is performed in the upstream region of the gasifier, A supply system for supplying water vapor to the downstream region so that a part of the carbon monoxide produced in the upstream region in the downstream region of the gasifier is shifted to hydrogen. Carbon monoxide mixed gas production equipment disclosed It has been.

  As a method for removing carbon dioxide contained in the product gas, a method using an absorbing liquid such as amine (for example, Patent Document 3), an adsorbent of carbon dioxide such as zeolite (for example, Patent Document 4), and the like have been disclosed. Yes.

  In Patent Document 3, the decarbonized exhaust gas from which carbon dioxide has been absorbed and removed by gas-liquid contact with an absorbing solution containing an amine compound in the carbon dioxide absorbing portion is brought into contact with cleaning water in the water-washing portion. In the amine recovery method for recovering an amine compound accompanying the decarbonation exhaust gas, the water washing section has a plurality of stages, and each stage is held in a liquid holding section provided on the inlet side of the water washing section. The washing water is transported to the outlet side of the flushing section and supplied to the flushing section. In the multiple-stage flushing section, the amine compound accompanying the decarbonation exhaust gas is sequentially recovered, and the carbon dioxide is collected. A demister is provided at the outlet of the carbon absorption unit and the water washing unit at each stage, and the absorption mist and washing water mist accompanying the decarbonized exhaust gas are removed by these demisters, and the water washing unit at the subsequent stage is removed. Kicking withdrawn washing water from the liquid holding unit, bypassing the preceding demister, amine recovery method and supplying discloses to the liquid holding portion in front of the washing unit or the front of the washing unit.

Further, Patent Document 4 discloses an adsorbent of carbon dioxide in a gas generation source, and a supporting rate of A-type or X-type zeolite having an Si / Al atomic ratio of 1.0 to 1.5 is 5 to 100 ( Mass%) and a bulk density of 0.05 to 1.00 (g / cm ³ ), and a carbon dioxide adsorbent having a honeycomb type, lattice type or spiral type structure is disclosed. ing.

JP-A-9-279163 JP 2001-139303 A JP 2007-190553 A JP 2004-202408 A

  In the hydrogen / carbon monoxide mixed gas production apparatus described in Patent Document 2, it is necessary to generate water vapor to be supplied to the gasifier outside the gasifier. In particular, when a part of the steam generated to be used for power generation in the steam turbine is supplied to the gasifier, the heat source for power generation is deprived, which reduces power generation efficiency and transports steam. There was room for improvement in that heat loss also occurred.

  The object of the present invention is to reduce the cost by reducing the water vapor supplied to the shift reaction equipment in a gasification system that produces a mixed gas of hydrogen and carbon monoxide while recovering carbon contained in carbon-based fuel as carbon dioxide. In addition, the heat loss associated with the generation and transportation of water vapor is reduced, and the thermal efficiency of the entire power generation system is improved.

  The gasification facility of the present invention includes a gasification furnace for gasifying carbon-based fuel, a fuel supply unit for supplying the carbon-based fuel, and an oxidant supply unit for supplying an oxidant. A gasification facility comprising a water supply pipe for supplying water for use in a shift reaction, and a water supply unit for directly connecting the water supply pipe and the gasification facility. To do.

  Moreover, the gasification system of this invention is characterized by including said gasification equipment and the carbon dioxide removal equipment for removing the carbon dioxide which generate | occur | produces in this gasification equipment.

  Furthermore, a power generation system of the present invention includes the gasification system described above and a generator for generating power using the gas produced by the gasification system.

  Furthermore, the operation method of the gasification system of the present invention includes a gasification furnace for gasifying a carbon-based fuel, a fuel supply unit for supplying the carbon-based fuel, and an oxidation for supplying an oxidant. A gasification facility comprising a water supply pipe for supplying water for use in a shift reaction, and a water supply section that directly connects the water supply pipe and the gasification equipment And a carbon dioxide removal facility for removing carbon dioxide generated in the gasification facility, and a method for operating a gasification system having a shift reaction facility between the gasification facility and the carbon dioxide removal facility. And calculating the ratio of water vapor and carbon monoxide in the shift reaction facility using the composition of the product gas downstream of the shift reaction facility, the ratio, the carbon-based fuel supply amount, the oxidant supply amount, and Previous Characterized in that it comprises a step of adjusting the supply amount of the water using a composition of the carbonaceous fuel.

  According to the present invention, since an indirect heat exchange facility for producing steam is unnecessary, plant construction costs are reduced.

  Further, according to the present invention, since the produced gas and water are brought into direct contact to produce water vapor, it is possible to provide gasification equipment and a gasification system with little heat loss and a power generation system using them.

  Furthermore, according to the present invention, a stable carbon recovery rate can be obtained even if the operating state of the gasification system varies.

It is a block diagram which shows typically the installation and flow path of the gasification system of Example 1 by this invention. It is a block diagram which shows typically the signal wiring of the gasification system of Example 1 by this invention. It is a block diagram which shows typically the installation and flow path of the gasification system which are the modifications of Example 1 by this invention. It is a block diagram which shows typically the signal wiring of the gasification system which is a modification of Example 1 by this invention. It is a block diagram which shows typically the installation and flow path of the gasification system of Example 2 by this invention. It is a block diagram which shows typically the signal wiring of the gasification system of Example 2 by this invention.

  The present invention relates to a gasification system including a carbon dioxide recovery facility and an operation method thereof.

  The present invention also relates to a system for gasifying carbon-based fuel, recovering carbon contained in the fuel from the exhaust gas as carbon dioxide, and producing a gas containing hydrogen as a main component. This is a contributing technology.

  The gasification system that recovers carbon dioxide from the product gas obtained by gasifying carbon-based fuel and produces a mixed gas of hydrogen and carbon monoxide is optimal depending on the target of the recovery rate of carbon contained in the carbon-based fuel. The configuration is different. However, for any gasification system, the water concentration in the product gas can be reduced by bringing water directly into contact with the product gas produced by the gasification equipment and using the operation method of the gasification system shown below. It becomes possible to make it a value required for a shift reaction.

  First, the means for solving the problem in the case where the target of the recovery rate of carbon contained in the carbon-based fuel is low will be described.

  When the target value of the carbon recovery rate is low, the water vapor concentration required for the shift reaction is also low, so that the amount of water brought into contact with the product gas produced by the gasification facility is small. Therefore, the temperature drop of the product gas is small, and the heat of the product gas can be recovered as steam by the indirect heat exchanger on the downstream side of the gasification facility. In this case, as a method for bringing the produced gas into contact with water, a method of spraying water on the gasification furnace of the gasification facility or the gasification furnace outlet is suitable, and the gasification system is operated by the following method. .

  The shift reaction is generally performed using a catalyst, and the amount of water vapor required per mole of carbon monoxide varies depending on conditions such as the type of catalyst, the amount of catalyst, and the catalyst layer temperature. The ratio of water vapor to carbon monoxide, the amount of carbon-based fuel supplied, the amount of oxidant supplied, the amount of produced gas and the composition of the produced gas, and the carbon-based fuel composition were used to determine the target concentration of carbon dioxide. The amount of water vapor contained in the product gas required to realize (ratio of the number of carbon moles contained in the product gas) is determined. Here, the carbon dioxide concentration target value is a numerical value defined by the following formula (2). In the following, carbon may be indicated by the element symbol C.

(CO ₂ concentration target value) = A / B (2)
(A: target value of the number of moles of CO ₂ contained in the produced gas per unit volume, B: number of moles of carbon contained in the produced gas per unit volume)
The required amount of water vapor is determined by the following formula (3).

(Required amount of water vapor) = {(target value of CO ₂ concentration) × (number of moles of carbon contained in product gas) − (number of moles of CO ₂ )} × r (3)
(R: ratio of water vapor to carbon monoxide)
The amount of water obtained by the above equation (3) is sprayed to the gasification furnace or the gasification furnace outlet in the gasification facility, and the total amount of water sprayed by the heat of the product gas is accompanied with the product gas as water vapor.

  As a method for removing carbon dioxide contained in the product gas, there are a method using an absorbing solution such as an amine solution and a method using an adsorbent such as zeolite. When the total amount of carbon dioxide contained in the product gas is removed by these methods, the target value of the carbon dioxide concentration is set so that the number of moles of carbon dioxide contained in the product gas satisfies the following formula (4). Good.

(Target value of the number of moles of CO ₂ ) = (Target value of the recovery rate of carbon contained in the carbon-based fuel) × (Number of moles of carbon contained in the carbon-based fuel) (4)
However, the method of removing carbon dioxide suppresses a decrease in thermal efficiency, and flows out downstream without being removed in a part of the carbon dioxide under the optimum operating conditions satisfying the plant specifications. Therefore, the target value of the carbon dioxide concentration is set higher than the value obtained as described above in consideration of the downstream outflow. The target value is adjusted by obtaining the recovery rate of carbon contained in the carbon fuel from the generated gas flow rate and gas composition before removing carbon dioxide and the gas composition after removing carbon dioxide, and this value is lower than the target value. The target value of the carbon dioxide concentration is increased, and if this value is higher than the target value, the target value of the carbon dioxide concentration is decreased.

  When water is sprayed on the gasification furnace or the gasification furnace outlet, the generated gas temperature is lowered. In order to advance the shift reaction downstream, the temperature of the product gas needs to be equal to or higher than the temperature at which gas can be passed to the shift reactor. Therefore, the temperature of each part, the amount of water supplied, the amount of generated gas, and the specifications of the heat recovery equipment can be used to predict the generated gas temperature at the shift reaction equipment inlet, and this temperature can be made higher than the temperature at which gas can pass through the shift reaction equipment The upper limit of the water supply amount is obtained, and the water supply amount is changed with this water supply amount as the upper limit.

  Next, means for solving the problem in the case where the target value of the recovery rate of carbon contained in the carbon-based fuel is low will be described. When the target value of the carbon recovery rate is high, the water vapor concentration necessary for the shift reaction is also high. For this reason, it is necessary to increase the amount of water brought into contact with the product gas in the gasification facility. For this reason, the temperature of the product gas is greatly reduced, and there is no room for recovering the heat of the product gas downstream of the gasification facility. For this reason, it is desirable to send the product gas directly to the downstream shift reaction facility. In this case, as a method of bringing the product gas into contact with water, a method of passing a water pool (liquid pool) is suitable. For example, a water washing tower is used. In the case of the gasification system configured as described above, the operation is performed as follows.

  To obtain the target carbon dioxide concentration using the ratio of water vapor to carbon monoxide, the amount of carbon-based fuel supplied, the amount of oxidant supplied in the shift reaction facility, and the composition of the carbon-based fuel The amount of water vapor (required water vapor amount) contained in the necessary generated gas is determined. Next, using the result of measuring the temperature and pressure of the product gas at the water outlet, the water vapor concentration after the product gas has passed through the water pool is predicted, and the amount of water vapor contained in the product gas at this time is obtained. If the amount of water is smaller than the amount of water vapor, the amount of water circulating in the puddle is reduced to raise the temperature of the water puddle. If the amount of water vapor is larger than the required amount of water vapor, the amount of water circulated in the water puddle is increased to lower the temperature of the water puddle. This utilizes the fact that the temperature of the product gas after passing through the puddle becomes equal to the temperature of the puddle, and the water vapor concentration contained in the product gas is a function of this temperature.

  Here, the water pool absorbs trace components such as unburned components and hydrogen chloride contained in the product gas, so the water in the water pool is discharged outside the washing tower to remove them, and the washing tower again. Recycle to return to the inside. The treated water is equal to the atmospheric temperature. When the amount of circulating water is small, the temperature of the puddle increases, and when the amount of circulating water is large, the temperature of the puddle decreases. In addition, since the water in the puddle comes into contact with the product gas and becomes water vapor and flows downstream, it is necessary to replenish the amount of water shown in the above formula (3). The carbon dioxide concentration target value setting method and the method of changing the amount of circulating water in the puddle so that the temperature of the gas produced at the puddle outlet is equal to or higher than the temperature at which gas can be passed to the shift reaction facility are used for carbon-based fuels. This is the same as when the target value of the recovery rate of contained carbon is low.

  In the present invention, the power generation system is a general term for the above gasification system and a generator for generating power using the gas produced by the gasification system, a coal gasification power plant, Includes fuel cell power generation systems.

  The present invention will be described below with reference to examples.

  The present embodiment relates to a gasification system and a method for operating the gasification system when the target value of the recovery rate of carbon contained in the carbon-based fuel is low. Here, the case where the target value of the carbon recovery rate is low refers to a case where the target value of the carbon recovery rate is set to about 60% assuming the carbon content rate of natural gas.

  FIG. 1 is a configuration diagram schematically showing equipment and flow paths of the gasification system of the present embodiment. FIG. 2 is a configuration diagram schematically showing signal wiring of the gasification system of the present embodiment.

  The gasification system in these drawings includes a gas generation facility 50 including a gasification facility 10, a heat recovery facility 20, a dust removal facility 30, a shift reaction facility 40, a water washing tower 51, and a hydrogen sulfide removal facility 53 from the upstream side. The carbon dioxide removal facility 60 is included.

  In FIG. 1, the gasification facility 10 includes a gasification furnace 101 and a product gas transfer unit 102, and a connection part between the gasification furnace 101 and the product gas transfer unit 102 is referred to as a gasification furnace outlet 103.

  In order to remove carbon from the product gas, it is necessary to react carbon dioxide and water vapor to form carbon dioxide and hydrogen, and to remove carbon dioxide from the product gas. Carbon monoxide is a flammable gas, and if carbon monoxide is removed directly, the calorific value of the product gas decreases, so it is necessary to convert carbon monoxide to carbon dioxide by a shift reaction. Steam is required for the shift reaction.

  The gasification facility 10 includes a fuel supply unit 111 for supplying the carbon-based fuel 1 (coal) and an oxidant supply unit 112 for supplying the oxidant 2 (oxygen or air). It has the water supply piping for supplying the water 4 for utilization, and the water supply part 113 which connects this water supply piping and the said gasification equipment directly. Here, the water 4 is a liquid at least upstream of the water supply pipe. That is, before the supplied water 4 reaches the water supply unit 113, it receives the heat of the gasification facility 10 and boils to become water vapor. In the present invention, it is important that a heat source and a heat exchanger for boiling the water 4 and piping for transporting the boiled water vapor are not necessary.

  Normally, the fuel supply unit 111 and the oxidant supply unit 112 are installed in the gasification furnace 101 located in the lower part of the gasification facility 10, but supply fuel to the generated gas moving unit 102 located in the upper part of the gasification facility 10. The unit 111 or the oxidant supply unit 112 may be installed.

  In this embodiment, the water supply unit 113 is installed at the gasification furnace 101 or the gasification furnace outlet 103 or in the vicinity thereof. In the present embodiment, since the fuel supply unit 111 and the oxidant supply unit 112 are installed in the gasification furnace 101 located in the lower part of the gasification facility 10, the installation position of the water supply unit 113 is the fuel supply unit 111. And on the downstream side of the oxidant supply unit 112. However, the installation position of the water supply unit 113 is not limited to this, and is configured to be able to supply water vapor to the high temperature part of the gasification furnace 101 or the product gas moving unit 102 at about 1300 ° C., As long as the temperature of the high temperature part of the gasification furnace 101 is not lowered more than necessary, the water supply part 113 may be installed in another part of the gasification facility 10.

  Here, the reason why it is desirable to supply water vapor to the high temperature part of about 1300 ° C. is because the shift reaction is difficult to proceed at a temperature below 1300 ° C. However, since the speed of the shift reaction increases rapidly at 1000 to 1300 ° C., the shift reaction can be performed using this temperature region. That is, it is possible to supply water vapor to a temperature range of 1000 to 1300 ° C.

  The carbon-based fuel 1 (coal) and the oxidant 2 (oxygen or air) are supplied to the gasification facility 10, and the carbon-based fuel 1 is gasified to become a product gas mainly composed of carbon monoxide and hydrogen. . Since this generated gas has a high temperature (about 1000 ° C.) at the outlet of the generated gas moving unit 102, the heat of the generated gas is recovered by the heat recovery facility 20 and cooled.

  In the present embodiment, water is sprayed (supplied) to the gasification furnace 101 and the gasification furnace outlet 103 of the gasification facility, and heat generated in the gasification furnace 101 (the walls of the gasification furnace 101 or the gasification furnace outlet 103). The water vapor can be obtained by evaporating the water with the sensible heat of the part or the product gas.

  In FIG. 2, the control device 70 includes an oxidant flow rate measurement unit 81, a carbon-based fuel flow rate measurement unit 82, a gasification facility temperature measurement unit 85, a feed water flow rate measurement unit 95, a gasification facility outlet temperature measurement unit 86, and a shift reaction. Equipment upstream temperature measurement section 87, shift reaction equipment downstream gas composition measurement section 89, gas purification equipment upstream flow measurement section 83, gas purification equipment downstream gas composition measurement section 90, carbon dioxide removal equipment upstream flow measurement section 84 Based on the value measured by the gas composition measuring unit 91 on the downstream side of the carbon dioxide removal equipment, the amount of water supply (spray amount) is calculated, and control for adjusting the opening of the water supply valve 71 is performed. The amount of water supply is adjusted by this control.

  The amount of water supplied in the control device 70 is calculated according to the following procedure.

  That is, the ratio of water vapor and carbon monoxide in the shift reaction facility 40 is calculated using the gas composition measured by the gas composition measuring unit 89 on the downstream side of the shift reaction facility, and together with this ratio, the carbon-based fuel flow rate measuring unit 82 and Included in the generated gas necessary to achieve the target value of carbon dioxide concentration using the carbon-based fuel supply amount and the oxidant supply amount measured by the oxidant flow rate measuring unit 81 and the known carbon-based fuel composition Determine the amount of water vapor that is generated. The control device 70 operates the water supply valve 71 so that a target amount of water is supplied by feedback control using the water vapor amount and the supply water flow rate measured by the supply water flow rate measuring unit 95.

  Here, when water is sprayed (supplied) to the gasification furnace 101 or the gasification furnace outlet 103 of the gasification facility 10, the generated gas temperature decreases. In order to advance the shift reaction in the downstream shift reaction facility 40, it is necessary to set the temperature of the product gas to a predetermined temperature or higher.

  Therefore, the gas temperature at the inlet of the shift reaction facility 40 is predicted from the temperature measurement result of each part, the temperature decrease due to the supply of the target amount of water, and the prediction result of the temperature decrease in the heat recovery unit. It is desirable to change the water supply amount in a range that is equal to or higher than the temperature at which gas can be passed to the shift reaction facility.

  Further, the ratio of water vapor and carbon monoxide in the shift reaction facility 40 and the carbon dioxide recovery rate in the carbon dioxide removal facility 60 may be higher or lower than the planned values. In such a case, the target carbon recovery rate may not be obtained.

  Therefore, the product gas flow rate 83 measured by the gas purification facility upstream flow rate measurement unit 83, the gas composition measured by the shift reaction facility downstream side gas composition measurement unit 89, and the gas measured by the carbon dioxide removal facility downstream side gas composition measurement unit 91 The carbon recovery rate from the carbon-based fuel is obtained using the composition. When this value is lower than the target value, the carbon dioxide concentration target value is increased, and when this value is higher than the target value, the carbon dioxide concentration target value is decreased.

  The product gas having an increased water vapor concentration is recovered by the heat recovery facility 20 and sent to the dust removal facility 30. Depending on the target value of the carbon recovery rate, it may not be possible to recover heat from the product gas after supplying water necessary for the shift reaction. In that case, as shown in FIGS. 3 and 4, the gasification system is configured without using the heat recovery equipment 20.

  In the dust removal equipment 30, fine particles such as char (unburned carbon) contained in the generated gas are collected using a cyclone 31 and an electric dust collector 32. The collected fine particles are recycled to the gasification furnace 101. The product gas after dedusting is sent to a COS converter 54 (also called a carbonyl sulfide converter) for reacting carbonyl sulfide (COS) contained in the product gas with water vapor to convert it into hydrogen sulfide and carbon dioxide. It is done. The COS converter 54 is filled with a titania-based or alumina-based catalyst. This is because the amine-based absorption liquid used in the hydrogen sulfide removal facility 53 does not absorb COS, so it is necessary to use COS as hydrogen sulfide in order to absorb the amine-based absorption liquid and achieve a high desulfurization rate. is there.

  If the shift reaction in the gasification facility 10 is not sufficient due to the configuration of the gasification system, it is desirable to provide the shift reaction facility 40 as the next stage of the COS converter 54 as shown in the present embodiment. The shift reaction facility 40 is filled with an iron-chromium or copper-zinc catalyst.

  The product gas after the shift reaction is guided to the gas purification facility 50, where hydrogen chloride and the like are removed by the water washing tower 51 of the gas purification facility 50, and hydrogen sulfide is removed by the hydrogen sulfide removal facility 53 of the gas purification facility 50.

  In order to increase the hydrogen chloride removal rate in the washing tower 51, the hydrogen ion concentration (pH) of the water supplied to the washing tower 51 may be made alkaline using sodium hydroxide or the like.

  The hydrogen sulfide removal equipment 53 uses an absorbing liquid 56 such as an aqueous amine solution. The absorbing liquid 156 that has absorbed hydrogen sulfide is sent to a regeneration tower (not shown), and the hydrogen sulfide contained in the absorbing liquid 156 is removed and recycled.

  The product gas from which hydrogen sulfide has been removed is sent to the carbon dioxide removal facility 60. Here, carbon dioxide is removed from the product gas, and the product gas 3 containing hydrogen as a main component is supplied downstream. As the absorbing liquid 55 used for carbon dioxide absorption, an aqueous amine solution or the like is used. The absorption liquid 155 that has absorbed carbon dioxide is sent to a regeneration tower (not shown), and carbon dioxide contained in the absorption liquid 156 is removed and recycled.

  The characteristics relating to the operation method of the gasification system described above are summarized as follows.

  Calculating the recovery rate of carbon contained in the carbon-based fuel 1 using the flow rate and composition of the product gas upstream of the carbon dioxide removal facility 60 and the composition of the product gas downstream of the carbon dioxide removal facility 60; Adjusting the target value of the carbon dioxide concentration according to the carbon recovery rate.

  Predicting the gasification facility 10 and the temperature upstream of the gasification facility 10, the amount of water supplied, and the product gas flow rate downstream of the shift reaction facility 40 to predict the product gas temperature upstream of the shift reaction facility 40; , A step of calculating an upper limit value of the amount of water that can make the generated gas temperature equal to or higher than a temperature at which gas can be passed to the shift reaction facility 40, and a step of changing the amount of supplied water within the range of the upper limit value Including.

  The present embodiment relates to a gasification system and a method for operating the gasification system when the target value of the recovery rate of carbon contained in the carbon-based fuel is high. Here, the case where the target value of the carbon recovery rate is high refers to the case where the target value of the carbon recovery rate is set to about 90%, assuming that carbon is recovered as much as possible.

  FIG. 5 is a configuration diagram schematically showing equipment and flow paths of the gasification system according to the second embodiment of the present invention. FIG. 6 is a configuration diagram schematically showing signal wiring of the gasification system according to the second embodiment of the present invention.

  In the present embodiment, the heat recovery equipment 20 is not used as in the gasification system shown in FIGS. 3 and 4.

  As shown in FIG. 5, the gasification system of the present embodiment has a gasification facility 10, a dust removal facility 30, a water washing tower 51, a COS converter 54, a shift reaction facility 40, a hydrogen sulfide removal facility 53, and an upstream side. The carbon dioxide removal facility 60 is included. The flush tower 51 is connected to the waste water treatment facility 52 so that the circulating water 6 treated in the waste water treatment facility 52 is supplied to the flush tower 51.

  In FIG. 6, the amount of the circulating water 6 is adjusted by the control device 70 with the opening degree of the valve 73.

  When the target value of the carbon recovery rate is high, the water vapor concentration necessary for the shift reaction is also high. Also, a large amount of water vapor is required. For this reason, there is much quantity of the water contacted with the product gas manufactured with the gasification equipment 10. FIG. For this reason, the temperature of the product gas is greatly reduced, and there is no room for recovering the heat of the product gas downstream of the gasification facility 10. For this reason, the generated gas is introduced into the dedusting facility 30 having the cyclone 230 to remove relatively large particles, and then supplied to the shift reaction facility 40 on the downstream side.

  In the present embodiment, a washing tower 51 having a liquid reservoir 252 at the bottom is used, and the generated gas is brought into contact with water.

  A venturi scrubber 251 is provided on the upstream side of the water washing tower 51. By introducing the water 4 to be supplied to the venturi scrubber 251 and atomizing the water 4, the removal efficiency of the fine particles contained in the generated gas is improved. It is improving. The product gas mixed with the water 4 is introduced into a liquid pool 252 at the bottom of the washing tower 51. The water 4 to be supplied to the washing tower 51 may be supplied from the upper part of the washing tower 51. The supply amount of the water 4 is changed by adjusting the opening degree of the water supply valve 72.

  The drainage water 5 of the washing tower 51 that has absorbed hydrogen chloride or the like is sent to the wastewater treatment facility 52 to remove the hydrogen chloride to form the circulating water 6, which is supplied from the upper part of the washing tower 51 and reused. A shelf 253 is provided inside the flush tower 51 to improve the removal efficiency of trace components such as hydrogen chloride contained in the product gas. Here, the flow rate of the waste water 5 can be adjusted by a valve 74.

  Furthermore, the water containing the char of the waste water treatment facility 52 is supplied to the gasification furnace 101 as the char-containing water 7 to gasify the char and use the moisture for the shift reaction in the gasification furnace 101. Here, it is desirable that the supernatant of the wastewater 5 to be treated by the wastewater treatment facility 52 is the circulating water 6 and the water having a high char concentration is the char-containing water 7.

  Thereby, the treatment of char becomes easy, and the amount of water to be replenished can be reduced.

  The supply system of the carbon-based fuel 1 and the oxidant 2 is the same as that in the first embodiment.

  In the present embodiment, as described above, by supplying the char-containing water 7 to the gasification furnace 101, moisture necessary for the shift reaction in the gasification furnace 101 is supplied. The product gas exiting the gasification facility 10 is sent to the dust removal facility 30, where unburned coal particles contained in the product gas are removed. The unburned coal particles are recycled to the gasifier. The product gas from which the fine particles have been removed is sent to the water washing tower 51.

  In order to make the amount of water vapor contained in the product gas at the outlet of the water-washing tower 51 necessary for the shift reaction, control is performed using the control device 70 in the following manner.

  First, in order to obtain the target value of the carbon dioxide concentration using the ratio of water vapor and carbon monoxide in the shift reaction facility 40, the supply amount of the carbon-based fuel 1, the supply amount of the oxidant 2, and the composition of the carbon-based fuel 1. The amount of water vapor in the required product gas (required water vapor amount) is determined.

  Next, after the product gas has passed through the water washing tower 51 using the results obtained by measuring the temperature and pressure of the product gas at the outlet of the water washing tower 51 by the water washing tower outlet temperature measuring unit 88 and the water washing tower outlet pressure measuring unit 85, respectively. Is estimated (calculated), and the amount of water vapor contained in the product gas at this time is obtained.

  When this amount of water vapor is smaller than the above required amount of water vapor, the opening of the water supply valve 73 is lowered to reduce the amount of circulating water 6 in the water washing tower 51 and the temperature of the liquid pool 252 at the bottom of the water washing tower 51 is raised. . If the amount of water vapor is larger than the required amount of water vapor, the opening of the water supply valve 73 is increased to increase the amount of circulating water 6 and the temperature of the liquid reservoir 252 is decreased.

  In addition to the circulating water 6, it is necessary to supply water 4 (make-up water) to the flush tower 51. This is because it is necessary to make up for the moisture that comes into contact with the product gas to form water vapor and flows out downstream of the washing tower 51. The amount of water 4 is equal to the amount of water that needs to be added to the product gas in the flush tower 51, but is adjusted so that the height of the liquid reservoir 252 at the bottom of the flush tower 51 is constant as necessary. .

  In addition, when the ratio of the water vapor | steam and carbon monoxide in the exit of the water-washing tower 51 cannot be raised to a target value, the water vapor | steam insufficient by a shift reaction is supplemented by supplying the water vapor | steam 8 to the shift reaction equipment 40.

  Although water equivalent to the amount of the circulating water 6 is extracted from the lower part of the flush tower 51, the height of the liquid reservoir 252 of the flush tower 51 is adjusted to be constant as necessary. The water 5 extracted from the water washing tower 51 is guided to the waste water treatment facility 52. Using a coagulation sedimentation apparatus (not shown), the waste water containing unburned coal particles is concentrated and recycled to the gasification furnace 101. The supernatant liquid with few unburned coal particles is recycled to the water washing tower 51 after removing fine particles and further removing trace components such as hydrogen chloride.

  The method for setting the target value of the carbon dioxide concentration is the same as in the first embodiment. Further, the method of changing the amount of the circulating water 6 in a range in which the generated gas temperature at the outlet of the liquid reservoir 252 is equal to or higher than the temperature at which gas can be passed to the shift reaction facility 40 is the same as in the first embodiment.

  The characteristics relating to the operation method of the gasification system described above are summarized as follows.

  A flush tower 51 having a water reservoir 252 for bringing the generated gas and water into contact with each other is provided on the downstream side of the gasification equipment 10. The flush tower 51 and the waste water treatment equipment 52 are connected to each other and treated by the waste water treatment equipment 52. The operation method of the gasification system having a configuration in which the recycled water 6 is supplied to the water washing tower 51, in the carbon-based fuel supply amount, the oxidant supply amount, the composition of the carbon-based fuel 1, and the shift reaction facility 40. Using the ratio of water vapor and carbon monoxide, the step of calculating the required water vapor amount in the shift reaction facility 40, the product gas temperature downstream of the gasification facility 10, and the temperature and pressure of the product gas in the flush tower 51 are used. Thus, the water vapor concentration after the product gas has passed through the water pool 252 is predicted, the amount of water vapor contained in the product gas at this time is calculated, and in order to bring this water vapor amount closer to the required water vapor amount, Flow And a step of controlling the.

  A step of measuring the temperature of the product gas upstream of the shift reaction facility 40 and changing the flow rate of the circulating water 6 in the water reservoir 252 within a range where the product gas temperature is equal to or higher than the temperature at which gas can be passed to the shift reaction facility 40. Including.

  1: Carbon fuel, 2: Oxidizing agent, 3: Product gas, 4: Water, 5: Drainage, 6: Circulating water, 7: Char-containing water, 8: Steam, 10: Gasification equipment, 20: Heat recovery equipment 30: Dedusting equipment, 40: Shift reaction equipment, 50: Gas purification equipment, 51: Water washing tower, 52: Waste water treatment equipment, 53: Hydrogen sulfide removal equipment, 54: COS converter, 60: Carbon dioxide removal equipment, 70: Control device, 113: Water supply unit.

Claims (2)

A gasification furnace for gasifying carbon-based fuel, a fuel supply unit for supplying the carbon-based fuel, and an oxidant supply unit for supplying an oxidant, and for use in a shift reaction water water supply pipe for supplying, and, a gasification facility having a water supply unit for connecting the water supply piping, downstream of the gasification facility, for contacting the product gas and water A water washing tower having a water reservoir, a carbon dioxide removal equipment for removing carbon dioxide generated in the gasification equipment, and a wastewater treatment equipment connected to the water washing tower, the gasification equipment and the carbon dioxide. have a shift reaction equipment between the carbon removal facilities, the wastewater treatment the treated circulating water method of operating a gasification system having the configuration supplied to the washing tower at facilities, the shift reaction equipment Of the product gas downstream And calculating the ratio of water vapor and carbon monoxide in the shift reaction facility using the composition, and supplying the water using the ratio, the carbon-based fuel supply amount, the oxidant supply amount, and the composition of the carbon-based fuel. Adjusting the amount, using the carbon-based fuel supply amount, the oxidant supply amount, the composition of the carbon-based fuel, and the ratio, calculating a required water vapor amount in the shift reaction facility, and the gasification Using the product gas temperature on the downstream side of the facility and the temperature and pressure of the product gas in the washing tower, the water vapor concentration after the product gas has passed through the water pool is predicted, and the water vapor contained in the product gas at this time A method for operating a gasification system, comprising: a step of calculating an amount; and a step of controlling the amount of circulating water so that the amount of water vapor approaches the amount of water vapor required . Measuring the temperature of the product gas upstream of the shift reaction facility, and changing the amount of circulating water in the water reservoir in a range where the product gas temperature is equal to or higher than the temperature at which gas can be passed to the shift reaction facility. The method for operating a gasification system according to claim 1 .

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