JP2009275680A - Nox emission amount forecasting method, operation method for gasification power generation plant utilizing this method, and gasification power generation plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently reduce an emission amount of NOx from a plant without being influenced by a variation of a concentration of NOx of a combustion emission gas caused by a composition of gasified gas fuel while preventing the excessive feeding of a reducing agent. <P>SOLUTION: The gasification power generation plant is provided with at least: a gasification device 3; a gas purification device 5; a combustion device for generating motive power by burning the gasified gas fuel 4a at a stoichiometric mixing ratio or lower; and a power generator. The plant is provided with a memory device 16 for storing a correlation function of a hydrogen concentration of the gasified gas fuel 4a and a conversion ratio to NOx in a combustion device of a nitrogen compound contained in the gasified gas fuel 4a; a hydrogen concentration measurement device 17 for measuring the hydrogen concentration of the gasified gas fuel; an operation device 11 for calculating the concentration of NOx of the combustion exhaust gas A based on the hydrogen concentration measured by the hydrogen concentration measurement device 17 and the correlation function; a reducing agent feeding means for feeding the reducing agent 10 to the combustion exhaust gas A; and a control means 14 for controlling an amount of the reducing agent 10 fed from the reducing agent feeding means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a NOx emission prediction method, a gasification power plant operating method using this method, and a gasification power plant. More specifically, the present invention relates to a gasification power plant operating method and a gasification power plant suitable for predicting and reducing the NOx emission amount discharged from the gasification power plant.

  In a gasification power plant, the product gas obtained by gasifying a gasification raw material with a gasifying agent is purified by a gas purification device to be gasified gas fuel, which is supplied to the combustion device and burned to drive power. And generate power by operating the generator using this power. In addition to this, by configuring a gasification combined cycle power plant that generates power by driving a steam turbine with steam generated using the heat of combustion exhaust gas from the combustion device, the power generation efficiency of the entire plant Improvements are also being made.

By the way, the product gas obtained by gasifying the gasification raw material with a gasifying agent contains a nitrogen compound (generally NH ₃ ), and when it is burned in a combustion apparatus, fuel NOx resulting from the nitrogen compound is generated. appear. Since NOx is a nitrogen oxide that becomes an air pollution source, it is necessary to exhaust the NOx amount from the gasification power plant after sufficiently reducing the amount of NOx.

Therefore, a method is known in which the produced gas is purified by wet refining using a water scrubber to remove NH _3, and gasified gas fuel from which NH ₃ which is a fuel NOx generation factor is removed is supplied to the combustion apparatus. Yes. In this case, in a combustion apparatus (for example, a gas turbine combustor), high efficiency has been achieved by increasing the temperature, but at that time, thermal NOx generated by oxidation of nitrogen (N ₂ ) in the air as a working medium. Is generated. This thermal NOx can be suppressed by adopting a method such as making the local high temperature region as small as possible by a uniform combustion method typified by lean premixed combustion (for example, Non-Patent Document 1). However, even if the product gas is subjected to wet purification, NH ₃ cannot be completely removed, and fuel NOx is generated due to the remaining NH ₃ .

In Patent Document 1, by catalytic catalytic combustion method utilizing the reduction of NH ₃ to N _2, to reduce the NH ₃ in the gasification gas in the fuel during combustion in the combustion device, suppresses the generation of fuel NOx A method has been proposed. However, this method has problems such as the life of the catalyst, and there is no example adopted in an actual plant. Further, NH ₃ cannot be reduced 100% to N ₂ , and generation of fuel NOx cannot be completely suppressed.

Therefore, conventionally, the combustion exhaust gas discharged from the combustion apparatus has been denitrated by a catalyst denitration system using a flue gas denitration facility and then discharged. Alternatively, after a denitration process is performed by a non-catalytic denitration system in which a reducing agent such as NH ₃ is supplied to combustion exhaust gas and NOx is reduced and denitrated in the gas phase, the denitration process is performed by a catalyst denitration system using a flue gas denitration facility.

JP 2002-66230 A Takeharu Hasegawa, et al., “Gas Turbine Combustor for Calorie Fuel during Coal Gasification (2nd Report, High Pressure Combustion Characteristics of NOx Reduction Enhanced Combustor by Lean Combustion)”, Japan Society of Mechanical Engineers, B, 69, 686 , Pp.2337-2345, 2003.

The composition of the gasification gas fuel varies depending on the type of gasification raw material, the type of gasification agent, the oxygen content of the gasification agent, the type of gasification furnace, the gasification furnace load, and the like. For example, as shown in Tables 1 and 2, the composition of the gasified gas fuel is largely composed of hydrogen (H ₂ ) and carbon monoxide (CO), but the composition ratio itself varies greatly. Yes. As for the amount of heat generated, the variation is seen between the low to medium calorie 2~13MJ / Nm ^3.

  Here, in order to improve the versatility of gasification power plants, it is required to be able to use not only fossil fuels but also various gasification raw materials, and plants of various sizes, large and small, are required depending on the location conditions. Become. For this reason, fluctuations in the NOx concentration of the combustion exhaust gas due to fluctuations in the composition of the gasified gas fuel are unavoidable problems.

However, the denitration process by the catalytic denitration method using the conventional flue gas denitration equipment cannot sufficiently cope with the load fluctuation to the flue gas denitration equipment due to the fluctuation of the NOx concentration of the combustion exhaust gas. That is, when the NOx removal treatment is performed by the catalyst removal method, if the NOx concentration in the combustion exhaust gas fluctuates, the treatment capacity of the catalyst may be exceeded, and NOx with a concentration exceeding the regulation value may be discharged. Even if the NOx concentration of NOx is reduced in the gas phase by supplying a reducing agent such as NH ₃ to the combustion exhaust gas and the NOx concentration is reduced, the regulation value will be exceeded There is a risk that NOx of concentration will be discharged. In addition, when combined with non-catalytic denitration-type denitration treatment, the amount of reducing agent such as NH ₃ supplied to the combustion exhaust gas becomes excessive with respect to the NOx concentration in the combustion exhaust gas, resulting in gasification of the reducing agent. There is also a risk of being discharged outside the power plant.

  Further, in a small-scale gasification power plant, it is often difficult to adopt advanced gas purification because of cost effectiveness, and there are cases where gas purification is not performed except for dust removal. Also in this case, if the amount of nitrogen compound contained in the gasified gas fuel is large, a large amount of fuel NOx may be generated. Therefore, it is not preferable to perform the denitration treatment by the catalyst denitration method from the viewpoint of the life and cost of the catalyst. The non-catalytic denitration type denitration process also has a problem that it is difficult to control the supply amount of the reducing agent and the denitration reaction itself due to fluctuations in the NOx concentration of the combustion exhaust gas.

  Therefore, there is an urgent need to establish a technique that can predict NOx concentration fluctuations in combustion exhaust gas caused by the composition of gasified gas fuel in advance and reduce NOx in accordance with the prediction result.

  Therefore, an object of the present invention is to provide a method capable of predicting in advance the variation in NOx concentration of combustion exhaust gas caused by the composition of gasified gas fuel.

  In addition, the present invention does not affect the NOx concentration in the combustion exhaust gas caused by the composition of the gasified gas fuel and the like, while preventing excessive supply of the reducing agent and sufficiently reducing the NOx emissions from the plant. An object of the present invention is to provide a gasification power plant operating method and a gasification power plant that can be reduced.

In order to solve such an object, the inventors of the present invention have made extensive studies, and as a result, when the gasification gas fuel is burned at a stoichiometric mixture ratio or less in the combustion apparatus, the combustion apparatus for NH ₃ contained in the gasification gas fuel is used. It has been found that the conversion rate of NOx to NOx has a unique relationship with the hydrogen concentration of the gasified gas fuel. Moreover, it has been found that this relationship is not affected by the molar ratio of CO and H ₂ occupying most of the gasified gas fuel, that is, the composition variation of CO and H ₂ . From this, by grasping in advance the correlation shown between the hydrogen concentration of the gasified gas fuel and the conversion rate of NH ₃ contained in the gasified gas fuel into NOx in the combustion device, the gasified gas fuel is obtained. From the measured value of the hydrogen concentration, it was found that the amount of NOx discharged from the combustion device can be predicted in advance, and the present invention has been achieved.

  The NOx emission prediction method according to claim 1 based on such knowledge includes a gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas, and a gas purification that purifies the product gas to obtain a gasified gas fuel. In a gasification power plant comprising at least an apparatus, a combustion apparatus that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less, and a generator that generates power using power, hydrogen of gasified gas fuel A correlation function indicating the relationship between the concentration and the conversion rate of nitrogen compounds contained in gasified gas fuel to NOx in the combustion device is obtained in advance, and the hydrogen concentration measurement value is obtained by measuring the hydrogen concentration of the gasified gas fuel. The NOx concentration of the flue gas exhausted from the combustion apparatus is predicted based on the acquired hydrogen concentration measurement value and the correlation function.

  Therefore, according to the NOx emission prediction method according to claim 1, from the measured value of the hydrogen concentration of the gasified gas fuel, the NOx in the combustion apparatus of the nitrogen compound contained in the gasified gas fuel and the hydrogen concentration of the gasified gas fuel is obtained. The NOx concentration of the combustion exhaust gas can be predicted based on a correlation function obtained in advance with respect to the correlation with the conversion rate.

In addition, the nitrogen compound contained in the gasification gas fuel in this specification means the nitrogen compound which becomes a generation source of fuel NOx when burned by the combustion device. Usually, most of the nitrogen compounds are NH ₃ , but in some cases, other than NH ₃ such as HCN is included, which means the conversion rate of all nitrogen compounds including these to fuel NOx.

  Next, the NOx emission amount prediction method according to claim 2 is a gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas, and a gas purification device that purifies the product gas to obtain a gasification gas fuel. A hydrogen concentration of the gasified gas fuel in a gasification power plant comprising: a combustion apparatus that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less; and a generator that generates power using the power. Is obtained in advance for each nitrogen compound concentration condition of the gasified gas fuel, and a correlation function indicating the relationship between the nitrogen compound contained in the gasified gas fuel and the NOx conversion rate in the combustion apparatus is determined. Measure the concentration to obtain the hydrogen concentration measurement value, measure the nitrogen compound concentration of the gasification gas fuel to obtain the nitrogen compound concentration measurement value, and obtain the correlation function of the nitrogen compound concentration condition that matches the nitrogen compound concentration measurement value Selection And, so that predicting the NOx concentration in the combustion exhaust gas discharged from the combustion device on the basis of the correlation function and the selected concentration of hydrogen measurements.

  Therefore, according to the NOx emission prediction method of claim 2, even if the nitrogen compound concentration of the gasification gas fuel fluctuates, the hydrogen concentration and gas of the gasification gas fuel are determined from the measured value of the hydrogen concentration of the gasification gas fuel. The NOx concentration of the combustion exhaust gas can be predicted based on a correlation function obtained in advance with respect to the correlation with the conversion rate of nitrogen compounds contained in the conversion gas fuel into NOx in the combustion apparatus.

  Next, the operation method of the gasification power plant according to claim 3 is a gasification apparatus that gasifies a gasification raw material with a gasifying agent to obtain a product gas, and a gas that purifies the gas to obtain a gasification gas fuel. In a gasification power plant comprising at least a refining device, a combustion device that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less, and a generator that generates power using power, A correlation function indicating the relationship between the hydrogen concentration and the conversion rate of nitrogen compounds contained in the gasified gas fuel to NOx in the combustion device is obtained in advance, and the hydrogen concentration of the gasified gas fuel is measured to measure the hydrogen concentration. To obtain a predicted NOx concentration value of the flue gas discharged from the combustion device based on the measured hydrogen concentration value and the correlation function, and control the amount of reducing agent supplied to the flue gas according to the predicted NOx concentration value Like To have.

  The gasification power plant according to claim 6 is a gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas, a gas purification device that purifies the product gas to obtain a gasification gas fuel, In a gasification power plant comprising at least a combustion device that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less, and a hydrogen concentration and gas of the gasified gas fuel A storage device for storing a correlation function obtained in advance for correlation with the conversion rate of nitrogen compounds contained in gasified gas fuel to NOx in the combustion device, and a hydrogen concentration measurement value by measuring the hydrogen concentration of the gasified gas fuel A hydrogen concentration measuring device for obtaining a NOx concentration calculated value of the combustion exhaust gas based on the hydrogen concentration measurement value and the correlation function, a reducing agent supply means for supplying a reducing agent to the combustion exhaust gas, a NOx concentration Based on the calculated value in which a control means for controlling the amount of reducing agent supplied from the reducing agent supply means.

  Therefore, according to the operation method of the gasification power plant according to claim 3 and the gasification power plant according to claim 6, the hydrogen concentration of the gasification gas fuel and the gasification gas are obtained from the measured value of the hydrogen concentration of the gasification gas fuel. The NOx concentration of the combustion exhaust gas can be predicted based on a correlation function obtained in advance with respect to the correlation with the conversion rate of nitrogen compounds contained in the fuel into NOx in the combustion apparatus. Therefore, the NOx concentration of the combustion exhaust gas can be reduced by supplying an optimal amount of the reducing agent according to the predicted value.

  Next, the operation method of the gasification power plant according to claim 4 is a gasification apparatus that gasifies a gasification raw material with a gasifying agent to obtain a product gas, and a gas that purifies the product gas to obtain a gasification gas fuel. In a gasification power plant comprising at least a refining device, a combustion device that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less, and a generator that generates power using power, A correlation function indicating the relationship between the hydrogen concentration and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained in advance for each nitrogen compound concentration condition of the gasified gas fuel. Measure the hydrogen concentration of the gas to obtain the hydrogen concentration measurement value, measure the nitrogen compound concentration of the gasification gas fuel to obtain the nitrogen compound concentration measurement value, and correlate the nitrogen compound concentration conditions that match the nitrogen compound concentration measurement value The number is selected, the NOx concentration predicted value of the flue gas discharged from the combustion device is obtained based on the measured hydrogen concentration value and the selected correlation function, and the reducing agent to the flue gas is determined according to the NOx concentration predicted value. The supply amount is controlled.

  The gasification power plant according to claim 8 is a gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas, a gas purification device that purifies the product gas to obtain a gasification gas fuel, In a gasification power plant comprising at least a combustion device that generates power by burning gasified gas fuel at a stoichiometric mixture ratio or less, and a hydrogen concentration and gas of the gasified gas fuel A storage device for storing a plurality of correlation functions obtained in advance for each nitrogen compound concentration of the gasification gas fuel for correlation with the conversion rate of nitrogen compounds contained in the gasification gas fuel into NOx in the combustion apparatus; A hydrogen concentration measuring device for measuring hydrogen concentration of fuel to obtain a measured value of hydrogen concentration, a nitrogen concentration measuring device for measuring nitrogen compound concentration of gasified gas fuel to obtain a measured value of nitrogen compound concentration, and nitrogen A calculation device that selects a correlation function of the nitrogen compound concentration condition that matches the compound concentration measurement value, obtains a NOx concentration calculation value of the combustion exhaust gas based on the hydrogen concentration measurement value and the selected correlation function, and a combustion exhaust gas A reducing agent supply means for supplying the reducing agent and a control means for controlling the amount of the reducing agent supplied from the reducing agent supply means based on the calculated NOx concentration are provided.

  Therefore, according to the operation method of the gasification power plant according to claim 4 and the gasification power plant according to claim 8, the hydrogen concentration of the gasification gas fuel is measured even when the nitrogen compound concentration of the gasification gas fuel fluctuates. From the value, the NOx concentration of the combustion exhaust gas is calculated based on a correlation function obtained in advance for the correlation between the hydrogen concentration of the gasification gas fuel and the conversion rate of nitrogen compounds contained in the gasification gas fuel into NOx in the combustion device. Can be predicted. Therefore, the NOx concentration of the combustion exhaust gas can be reduced by supplying an optimal amount of the reducing agent according to the predicted value.

  Here, as in the inventions of claims 5, 7 and 9, the correlation between the optimum reaction temperature for the reduction of NOx in the combustion exhaust gas and the CO concentration of the combustion exhaust gas is obtained in advance, and the CO concentration of the combustion exhaust gas is determined. To obtain a measured value of CO concentration, obtain an optimum predicted reaction temperature value based on the measured CO concentration value and the above correlation, and apply a reducing agent to the flue gas in a temperature range suitable for the predicted optimum reaction temperature value. It is preferable to supply.

  The temperature of the combustion exhaust gas discharged from the combustion device decreases as it goes from the combustion device outlet to the subsequent stage of the gasification power plant. Therefore, by supplying the reducing agent to the combustion exhaust gas in the temperature range optimal for the NOx reduction reaction while setting the supply amount of the reducing agent to the optimal amount with respect to the NOx concentration of the combustion exhaust gas, the NOx concentration of the combustion exhaust gas is reduced. It can be surely reduced.

  According to the NOx emission amount predicting method according to claim 1 or 2, the NOx concentration of the combustion exhaust gas can be predicted. Therefore, it becomes easy to implement a measure for reducing the NOx concentration of the combustion exhaust gas, and the gasification power plant. Operability can be improved.

  Further, according to the operation method of the gasification power plant according to claim 3 or 4, and the gasification power plant according to claim 6 or 8, the NOx concentration of the combustion exhaust gas is predicted, and an optimum amount is determined according to the prediction result. It becomes possible to supply the reducing agent. Therefore, it is possible to reduce the NOx emission amount from the gasification power plant without depending on the fluctuation of the NOx concentration of the combustion exhaust gas caused by the composition of the gasification gas fuel. In addition, since an optimal amount of reducing agent can be supplied according to the predicted NOx concentration value of the combustion exhaust gas, excessive supply of the reducing agent can be prevented, and the reducing agent is discharged out of the gasification power plant. Can be prevented.

  Furthermore, according to the operation method of the gasification power plant according to claim 5 and the gasification power plant according to claim 7 or 9, the prediction of the NOx concentration of the combustion exhaust gas and the prediction of the optimum reaction temperature for the reduction of NOx It is possible to supply an optimum amount of the reducing agent to the optimum position according to the prediction result. Therefore, the amount of NOx discharged from the gasification power plant can be reliably reduced without depending on the fluctuation of the NOx concentration of the combustion exhaust gas caused by the composition of the gasification gas fuel. Moreover, since an optimal amount of reducing agent can be supplied according to the predicted value of the NOx concentration of the combustion exhaust gas, excessive supply of the reducing agent can be reliably prevented, and the reducing agent is discharged out of the gasification power plant. Can be surely prevented.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings. In the following embodiments, the nitrogen compound contained in the gasified gas fuel is described as NH ₃ , but the present invention can also be applied to other nitrogen compounds other than NH ₃ .

(First embodiment)
The gasification power plant of the present invention predicts the NOx concentration of combustion exhaust gas using the measured value of the hydrogen concentration of the gasification gas fuel, and supplies an optimal amount of reducing agent to the combustion exhaust gas based on the prediction result. Thus, the NOx concentration in the combustion exhaust gas can be reduced while preventing excessive supply of the reducing agent and preventing leakage of the reducing agent from the plant. More specifically, when the type of gasification raw material supplied to the gasifier changes, or when the gasification conditions (type of gasification agent, oxygen content of gasification agent, type of gasification furnace, etc.) Even if the NOx concentration of the combustion gas FG changes due to the fluctuation, the fluctuation is predicted in advance from the hydrogen concentration of the gasification gas fuel, and an optimum amount of reducing agent is burned according to the prediction result. The NOx concentration of the combustion exhaust gas can be reduced without supplying the exhaust gas and causing the reducing agent to leak out of the gasification power plant.

  A first embodiment of the gasification power plant of the present invention is shown in FIG. In this embodiment, a gas turbine is described as an example of the combustion device. However, any combustion device that generates power by combustion can be used without being limited to the gas turbine. For example, a boiler, a gas engine (reciprocating engine), etc. can also be used as a combustion device.

The gasification power plant of the first embodiment includes a gasification device 3 that gasifies a gasification raw material 1 with a gasifying agent 2 to obtain a product gas 4, and a gasification gas fuel 4a obtained by purifying the product gas 4 The gas purification apparatus 5 and the gas turbine 6 (6a-6c) which burns the gasification gas fuel 4a are provided. In the gas turbine 6, the compressed air HA supplied from the air compressor 6 a that compresses the air AR that is a working medium is supplied to the gas turbine combustor 6 b together with the gasified gas fuel 4 a to be burned, and high-temperature and high-pressure combustion gas is produced. G is introduced into the expansion turbine 6c and driven, and power is generated by the generator 7 coupled to the expansion turbine 6c. The apparatus configuration for predicting the NOx concentration of the combustion exhaust gas FG discharged from the gas turbine 6 (6a to 6c) is as follows. That is, a storage device 16 that stores a correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine 6; The hydrogen concentration measuring device 17 that measures the hydrogen concentration of the gasified gas fuel 4a, and the NOx concentration of the combustion exhaust gas A based on the correlation function stored in the storage device 16 from the hydrogen concentration measured by the hydrogen concentration measuring device 17 By the calculation device 11 to be calculated, predicted NOx concentration values of the combustion gas G discharged from the gas turbine combustor 6b and the combustion exhaust gas A discharged from the expansion turbine 6c are obtained.

  The combustion exhaust gas A is a general term for the combustion gas G discharged from the gas turbine combustor 6b and the combustion exhaust gas FG discharged from the expansion turbine 6c. That is, it means “combustion exhaust gas discharged from the combustion apparatus” in the present invention.

The gasification power plant according to the present embodiment includes a reducing agent supply means 13 that supplies a reducing agent 10 for reducing and removing NOx contained in the combustion exhaust gas A by reducing and decomposing it into N ₂ in the gas phase. Based on the NOx concentration calculated by the apparatus 11, the amount of the reducing agent 10 supplied from the reducing agent supply means 13 is controlled by the control means 14. The combustion exhaust gas FG from which NOx has been decomposed and removed into N ₂ is discharged from the chimney 9.

  In the gasification power plant according to the present embodiment, the exhaust heat recovery device 8 that recovers the heat of the combustion exhaust gas FG and the steam ST by the exhaust heat recovery device 8 using the condensate FW supplied from the condenser 15. And steam power generation by a steam cycle in which the steam turbine 20 is driven by the steam ST to generate power. However, this configuration using steam cycle power generation is intended to increase the efficiency of the gasification power plant, and is not an essential configuration in the gasification power plant.

  Hereinafter, the gasification power plant according to the present embodiment will be described in more detail.

  Examples of the gasification raw material 1 include, but are not limited to, coal, petroleum, biomass, waste, and the like.

  Examples of the gasifying agent 2 include, but are not limited to, oxygen, air, oxygen-enriched air, and the like.

  The gasifier 3 is not particularly limited as long as the gasifier 1 is gasified with the gasifying agent 2 to obtain the product gas 4. For example, a fixed bed, spouted bed type gasification furnace or the like can be used.

Examples of the gas purification device 5 include a dry purification device that removes impurities such as sulfur and ash from the product gas 4, and a wet purification device that removes NH ₃ as well as impurities such as sulfur and ash from the product gas 4. . In addition, depending on the combustion apparatus and gasification power generation equipment used, a gas purification apparatus that removes only soot by a filter or the like is also included.

  The gas turbine (combustion device) 6 burns the gasified gas fuel 4a at a stoichiometric mixture ratio or less to generate power for operating the generator 7. Here, the meaning of “combusting the gasified gas fuel 4a at a stoichiometric mixture ratio or less” means that the combustion method is not a combustion method in which the gasification gas fuel 4a is combusted by a reduction combustion method. In other words, it means that the gasified gas fuel 4a is burned with an oxygen equivalent to (stoichiometric amount) or more or a gas containing oxygen equivalent to or more. Specific examples include diffusion combustion that is most commonly used in gas turbines, engine engines, and the like, and quasi-uniform combustion typified by partially lean premixed combustion, but are not limited thereto.

When the gasified gas fuel 4a is burned at a stoichiometric mixture ratio or lower, fuel NOx resulting from NH ₃ contained in the gasified gas fuel 4a is generated. That is, even when the product gas 4 is wet-purified by the gas purification device 5, NH ₃ cannot be completely removed, and fuel NOx is generated due to the residual NH ₃ . Further, when the gas purification device 5 performs dry purification of the product gas 4 or purification for removing only dust, NH ₃ is not removed from the product gas 4, and fuel NOx is generated due to this. The present invention provides a value that is an index of the fuel NOx concentration of the combustion exhaust gas A, that is, the conversion rate of NH ₃ contained in the gasified gas fuel 4a to NOx in the gas turbine combustor 6b and the hydrogen concentration of the gasified gas fuel 4a. The NOx concentration of the combustion exhaust gas A is predicted on the basis of a correlation function indicating the correlation.

  For example, in recent years, a small-scale power generation facility that employs a gas engine such as a reciprocating engine as a combustion device is being studied. In such a small-scale power generation facility, from the viewpoint of preventing the loss of sensible heat of gasified gas fuel, gasified gas fuel that has been subjected to dry refining or purification treatment that excludes only dust is often used. In a gas engine such as a reciprocating engine, gasified gas fuel is generally burned at a stoichiometric mixture ratio or less. Accordingly, there is a concern that fuel NOx is likely to be generated from the gasification power plant, but the present invention predicts the NOx concentration of the combustion exhaust gas discharged from the gas engine even under such a situation. It is something that can be done.

Next, the storage device 16 is, for example, a hard disk, a RAM, or the like. The storage device 16 stores a correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b. Has been.

  The hydrogen concentration measuring device 17 is not particularly limited as long as it can measure the hydrogen concentration of the gasified gas fuel 4a. For example, a gas chromatograph device (device name: AG-1000TTH, manufacturer name) : Yanaco Analytical Industrial Co., Ltd.) may be used. Note that the hydrogen concentration of the gasified gas fuel 4 a is measured before the gasified gas fuel 4 a is supplied to the combustion device 6. Thereby, the NOx concentration of the combustion exhaust gas A derived from the gasified gas fuel 4a combusted by the combustion device 6 can be predicted in advance.

  The arithmetic device 11 and the control means 14 are comprised by CPU (central processing unit) or MPU (microminiature arithmetic device).

  In the arithmetic unit 11, arithmetic processing is performed based on the correlation function stored in the storage device 16 and the hydrogen concentration measurement data input from the hydrogen concentration measuring device 17, and reduction is performed by the control means 14 based on the arithmetic result. A command signal is sent to the agent supply means 13, its operation is controlled, and the reducing agent 10 is supplied to the combustion exhaust gas A. In this embodiment, the flue gas denitration facility 12 is provided in the flow path of the flue gas A, and NOx in the flue gas A is reduced by supplying the reducing agent 10 to the flue gas denitration facility 12. The supply method of the reducing agent 10 is not limited to this. For example, the reducing agent 10 may be directly supplied to a line through which the combustion exhaust gas A circulates, or the reducing agent 10 may be supplied to both the line through which the combustion exhaust gas A circulates and the flue gas denitration facility 12. Good.

The reducing agent 10 is not particularly limited as long as it is a substance that can reduce NOx. For example, ammonia (NH ₃ ) or urea can be used.

  The reducing agent supply means 13 includes a tank 13a for storing the reducing agent 10 and a valve 13b for controlling the supply of the reducing agent 10 from the tank 13a to the combustion exhaust gas A by an opening / closing operation. In the present embodiment, the reducing agent 10 is supplied to the combustion exhaust gas A flowing into the exhaust heat recovery device 8 and the exhaust gas denitration equipment 12, and the denitration process by the non-catalytic denitration system and the denitration process by the catalytic denitration system are performed. Although used together, it is not necessarily limited to this form. For example, the reducing agent 10 may be supplied before the exhaust heat recovery device 8. Further, when the NOx concentration of the combustion exhaust gas A is sufficiently lowered before the exhaust gas denitration facility 12, the supply line of the reducing agent 10 to the exhaust gas denitration facility 12 may be omitted. A solenoid or the like that is driven in response to a command signal from the control means 14 is incorporated, and the valve 13b opens and closes as the solenoid is driven. The supply amount of the reducing agent 10 may be controlled by adjusting the opening of the valve 13b of the reducing agent supply means 13, or by adjusting the opening time. Further, when the reducing agent 10 is supplied, it is preferable that the reducing agent 10 is diluted with a medium such as water and sprayed from a nozzle or the like so that the reducing agent 10 contacts the entire combustion gas A. .

The supply amount of the reducing agent 10 may be an amount corresponding to the NOx concentration and equivalent of the combustion exhaust gas A. For example, when NH ₃ is used as the reducing agent 10, from the chemical reaction formula 1 below, the amount of NH ₃ required for the reduction of 1 mol of NOx is theoretically 1 mol. NH ₃ may be supplied. However, when the decomposition rate of the reducing agent 10 is lower than the NOx reductive decomposition rate, the reducing agent 10 has an amount equivalent to the NOx concentration and equivalent of the combustion exhaust gas A in consideration of these ratios. It is preferable to adjust the supply amount of the resin to be small.
(Chemical reaction formula 1) NO + NH ₃ + 1 / 4O ₂ → N ₂ + 3 / 2H ₂ O

  In this way, by supplying the reducing agent 10 according to the predicted value of the NOx concentration of the combustion exhaust gas A, the concentration of NOx contained in the combustion exhaust gas A is sufficiently reduced while preventing the supply of excessive reducing agent. Can do. Therefore, the NOx concentration of the combustion exhaust gas A can be reduced at the stage before flowing into the flue gas denitration facility 12, and the load on the catalyst of the flue gas denitration facility 12 can be greatly reduced, and the catalyst replacement interval is long. It is possible to reduce time and cost and time and cost for managing the exhaust gas denitration facility 12. In addition, if the concentration of NOx contained in the combustion exhaust gas A can be sufficiently reduced below the regulation value while preventing excessive supply of the reducing agent before the exhaust gas denitration facility 12, the exhaust gas denitration facility 12. Can be omitted.

Next, from the correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b, the combustion exhaust gas A A method for obtaining the NOx concentration will be described in detail.

The correlation between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b can be obtained as follows. That is, when the combustion conditions in the gas turbine combustor 6b are constant and the NH ₃ concentration of the gasified gas fuel 4a is constant, a plurality of hydrogen concentration conditions of the gasified gas fuel 4a are set, and the respective hydrogen concentration conditions are by measuring the rate of conversion into NOx of NH _3, it can be found a unique relation between the hydrogen concentration conditions and conversion to NOx of NH ₃ in the gasification gas fuel 4a.

The conversion rate (CR) of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b is expressed by the following formula 1.

In Equation 1, [NOx] is the total NOx concentration in the combustion exhaust gas A combustion apparatus (gas turbine combustor 6b), _{[NOx th]} is the thermal NOx concentration, [NH _3] is NH gasification gas fuel ₃ concentrations. The fuel NOx concentration is obtained as a difference between [NOx] and [NOx _th ].

The thermal NOx concentration can be obtained by measuring the NOx concentration of the combustion exhaust gas when the NH ₃ concentration of the gasified gas fuel supplied to the combustion apparatus is 0. The NOx concentration can be measured by, for example, a chemiluminescence method using a MEXA9100 analyzer manufactured by Horiba.

Since the NH ₃ concentration is a constant value, that value may be applied.

  The total NOx concentration of the combustion exhaust gas A can be determined by the chemiluminescence method using a MEXA9100 analyzer manufactured by Horiba, for example, as described above.

Measuring the total NOx concentration in the combustion exhaust gas A to a plurality of gasification gas fuel 4a of the hydrogen concentration conditions, by acquiring data, and conversion to NOx concentration of hydrogen and NH ₃ in the gasification gas fuel 4a The relationship can be uniquely determined. Specifically, in the region where the hydrogen concentration is low (for example, 30 vol% or less), the conversion rate decreases linearly as the hydrogen concentration increases, and in the region where the hydrogen concentration is high (for example, more than 30 vol%), hydrogen The conversion rate increases gradually as the concentration increases. From this relationship, an approximate expression can be obtained by, for example, the least square method.

Therefore, by using this approximate expression, when the combustion condition of the combustion apparatus (gas turbine combustor 6b) and the NH ₃ concentration condition are constant, the measurement value of the hydrogen concentration of the gasified gas fuel 4a is obtained. The conversion rate of NH ₃ to NOx can be determined. Then, from the conversion rate of NH ₃ to NOx, the total NOx concentration taking into account the fuel NOx concentration and the thermal NOx concentration can be predicted.

Here, in the above-described prediction method, the NH ₃ concentration of the gasified gas fuel 4a is constant. However, the hydrogen concentration of the gasified gas fuel 4a and the gas turbine combustor 6b of NH ₃ contained in the gasified gas fuel 4a are used. A plurality of correlations with the conversion rate to NOx may be obtained for each NH ₃ concentration condition. In this case, by measuring the NH ₃ concentration of the gasification gas fuels 4a, select the correlation function obtained when the NH ₃ concentration measurement under the same conditions of the NH ₃ concentration, using the correlation function From the measured value of the hydrogen concentration of the gasified gas fuel 4a, the conversion rate of NH ₃ into NOx can be obtained. That is, a correlation function that matches the measured value of the NH ₃ concentration of the gasified gas fuel 4a may be selected and used as a correlation function for determining the conversion rate of NH ₃ to NOx. In this case, it is possible to predict the conversion rate of NH ₃ to NOx for all NH ₃ concentrations. In the case of changing the NH ₃ concentration of the gasification gas in the fuel to about 0～3000Ppm, it has been confirmed by the present inventors experiments the conversion rate with increasing NH ₃ concentration tends to decrease.

In this case, the gasification power plant shown in FIG. 1 is a device that measures the NH ₃ concentration of the gasified gas fuel 4a before being supplied to the combustion device 6 (for example, an ammonia concentration meter (NH -26: Kyoto Electronics Manufacturing Co., Ltd.)) further comprises a in the storage device 16, NH ₃ is stored a plurality of the correlation function for each concentration conditions, consistent with the NH ₃ concentration measured by the apparatus for measuring the NH ₃ concentration The correlation function of the NH ₃ concentration condition to be selected can be selected by the arithmetic unit 11 to obtain the conversion rate of NH ₃ to NOx from the measured hydrogen concentration.

(Second embodiment)
FIG. 2 shows a second embodiment of the gasification power plant of the present invention.

  The gasification power plant according to the second embodiment is different from the gasification power plant according to the first embodiment in the following points.

That is, the storage device 16 has a correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b. In addition, the correlation between the reaction temperature optimum for NOx reduction and the CO concentration is also stored.

  Further, a CO concentration measuring device 18 for measuring the CO concentration of the combustion exhaust gas A is provided.

  Furthermore, the configuration of the reducing agent supply means 13 is different. That is, the reducing agent supply means 13 of the gasification power plant according to the second embodiment includes a plurality of reducing agent supply units 13c that can supply the reducing agent 10 to positions where the temperature of the combustion exhaust gas A is different. The control unit 14 not only controls the amount of the reducing agent 10 supplied from the reducing agent supply unit 13, but also the reducing agent supply unit 13c at a position suitable for the optimum reaction temperature among the plurality of reducing agent supply units 13c. Control to select is performed.

  In short, in the gasification power plant according to the second embodiment, in addition to the control of the supply amount of the reducing agent 10 according to the NOx concentration of the combustion exhaust gas A in the first embodiment, the optimum reaction of the above chemical reaction formula 1 It is characterized in that the CO concentration of the combustion exhaust gas A that affects the temperature is measured, and the optimum supply position of the reducing agent 10 is determined from the measured value of the CO concentration. CO present in the combustion exhaust gas A is an unburned component in the gas turbine combustor 6b. The temperature of the combustion exhaust gas A gradually decreases from the outlet of the gas turbine combustor 6b to the chimney, so that the positive direction of the chemical reaction formula 1 (the direction toward the right side of the chemical reaction formula 1). The NOx concentration is surely reduced by supplying the reducing agent 10 to the combustion exhaust gas in the optimum reaction temperature range that promotes the reaction (1).

The correlation between the optimum reaction temperature for the reduction of NOx and the CO concentration can be obtained as follows. That is, in the plurality of reaction temperature zones, the chemical reaction formula 1 is advanced while varying the CO concentration, and the reaction temperature zone in which the reductive decomposition of NOx into N ₂ and the decomposition of NH ₃ into N ₂ occur most efficiently. That is, the “reaction window” is searched and set as the optimum reaction temperature zone. Then, by obtaining the relationship between the optimum temperature zone and the CO concentration, a correlation between the optimum reaction temperature for the reduction of NOx and the CO concentration can be obtained. This correlation may be obtained experimentally, or may be obtained by theoretical calculation using numerical analysis in consideration of elementary reactions. Further, it may be obtained by creating a database using a plurality of documents.

  The CO concentration measuring device 18 is not particularly limited as long as it can measure the CO concentration. For example, a non-dispersive infrared absorption method (IRA-106: Shimadzu Corporation) may be used. The CO concentration is preferably measured near the outlet of the gas turbine combustor 6b.

  By measuring the CO concentration by the CO concentration measuring device 18, the optimum reaction temperature for NOx reduction is predicted based on the correlation stored in the storage device 16.

  Next, the reducing agent supply unit 13 c of the reducing agent supply unit 13 includes a thermocouple (not shown), and the temperature of the combustion exhaust gas A at each position of the reducing agent supply unit 13 c is transmitted to the control unit 14. The Then, based on the prediction result of the NOx concentration of the combustion exhaust gas A and the prediction result of the optimum reaction temperature, the control of the supply amount of the reducing agent 10 and the reducing agent supply unit 13c in the combustion exhaust gas temperature band suitable for the optimum reaction temperature are performed. Control for selecting is performed by the control means 14.

  With the above configuration, the amount of NOx discharged from the gasification power plant can be reliably reduced. Therefore, the NOx concentration of the combustion exhaust gas A can be reduced at the stage before flowing into the flue gas denitration facility 12, and the load on the catalyst of the flue gas denitration facility 12 can be greatly reduced, and the catalyst replacement interval is long. It is possible to reduce time and cost and time and cost for managing the exhaust gas denitration facility 12. Further, in the previous stage of the flue gas denitration facility 12, it is easy to sufficiently reduce the concentration of NOx contained in the combustion exhaust gas A to be below the regulation value while preventing excessive supply of the reducing agent. Is easy to realize. That is, in the present embodiment, the flue gas denitration facility 12 and a line for supplying the reducing agent 10 to the flue gas denitration facility 12 are provided, but in the preceding stage of the flue gas denitration facility 12, the supply of excessive reducing agent is prevented. When the concentration of NOx contained in the combustion exhaust gas A can be sufficiently reduced to be below the regulation value, the exhaust gas denitration equipment 12 and the line for supplying the reducing agent 10 to the exhaust gas denitration equipment 12 can be omitted. .

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, N _{2 O} and NO ₂ components contained in the combustion exhaust gas A, even more upon adding the effect of CH ₄ or H ₂ component has on the reduction reaction of NOx, so as to perform optimization of the gas phase denitration reaction Also good.

In the above-described embodiment, the nitrogen compound that causes fuel NOx generation is described as NH _3. However, the conversion rate of all nitrogen compounds including other nitrogen compounds that cause fuel NOx generation, such as HCN, to NOx is increased. On the other hand, the present invention may be applied.

Furthermore, in the method for predicting NOx emissions in the above-described embodiment, since the combustion conditions in the combustion apparatus of the gasification power plant are normally constant, the NOx emissions are predicted without taking combustion conditions into account. However, a plurality of correlations between the hydrogen concentration of the gasified gas fuel 4a and the conversion rate of NH ₃ contained in the gasified gas fuel 4a into NOx in the gas turbine combustor 6b are obtained for each combustion condition. Also good. In this case, the correlation function obtained when the combustion condition is the same as the combustion condition for operating the combustion apparatus is selected, and the NH value from the measured value of the hydrogen concentration of the gasified gas fuel 4a is calculated using this correlation function. Conversion rate of ₃ to NOx can be obtained. That is, a correlation function that matches the combustion conditions for operating the combustion apparatus may be selected and used as a correlation function for determining the conversion rate of NH ₃ to NOx. In this case, it is possible to predict the conversion rate of NH ₃ to NOx for all combustion conditions.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
An experiment was conducted using a combustor 30 (see FIG. 3) comprising a cylindrical combustion chamber 31 having an inner diameter of 90 mm and a length of 1000 mm, an inner side covered with a refractory material, a primary air introduction part 32 and a fuel injection nozzle 33. All the combustion air was supplied from the primary air introduction section 32.

  The test burner used in this experiment consisted of a fuel injection nozzle with a caliber of 1.5 mm × 12, a blowing angle θ = 90 °, a primary air swirler with an inner diameter of 24.0 mm, an outer diameter of 36.4 mm, and a swivel angle of 45 °. did. The swirl number S was 0.84.

First, using the combustor 30, the fuel calorific value (HHV: higher calorific value) of the gasification gas fuel and the conversion rate of NH ₃ contained in the gasification gas fuel into NOx in the combustor 30 (hereinafter referred to as NH ₃ ). relationship between ₃ is referred to as a conversion to NOx of), were studied molar ratio of CO and H ₂ is the major combustible components of gasification gas fuel as parameters.

The experimental conditions were as follows. The NH ₃ concentration in the gasified gas fuel was 1000 ppmv, and the CH ₄ concentration was 0 ppm. The average temperature (T _ex ) of the gas discharged from the combustor was maintained at 1773K. The CO / H ₂ (molar ratio) in the gasified gas fuel is 0.43, 1.00, and 2.33, and while maintaining this condition, the fuel heating value of the gasified gas fuel is adjusted by dilution with N ₂ The combustion temperature T _ex was adjusted by the air supply amount.

The combustion exhaust gas is sampled by a water-cooled probe (one point) inserted on the central axis of the combustion chamber outlet duct, and CO and CO ₂ are analyzed by a non-dispersive infrared absorption method. NOx, O ₂ and THC are respectively measured by a chemiluminescence method and a magnetic field. The concentration was measured by a pressure method and a flame ion detection method (using a MEXA9100 analyzer manufactured by Horiba, Ltd.). All experiments were performed at atmospheric pressure.

The results are shown in FIG. In FIG. 4, T _air is the temperature (K) of the supply air, T _fuel is the temperature (K) of the supplied gasification gas fuel, and V _fuel is the gasification gas fuel to the combustor 30. It is the injection speed (m / s) in the fuel nozzle.

From the results shown in FIG. 4, it was confirmed that there was a difference in the conversion ratio of NH ₃ to NOx depending on the molar ratio of CO and H ₂ . From this, it has been clarified that even if the conversion rate of NH ₃ to NOx is arranged with respect to the higher calorific value of the gasified gas fuel, it is not unique.

Therefore, as a result of examining the factors that fluctuate the NOx concentration of combustion exhaust gas from various parameters, the result shown in FIG. 4 is obtained by using the hydrogen concentration of gasification gas fuel as the horizontal axis and the conversion rate of NH ₃ to NOx as the vertical axis. By using the axis, it became clear that there is a unique correlation between the hydrogen concentration of the gasified gas fuel and the conversion rate of NH ₃ to NOx. The results are shown in FIG.

From the results shown in FIG. 5, the unambiguous correlation between the hydrogen concentration of the gasification gas fuel and the conversion rate of NH ₃ to NOx is that of CO and H ₂ which are the main components of the gasification gas fuel. It became clear that it did not depend on the molar ratio.

Next, an approximate expression was obtained from the results shown in FIG. 5 using the least square method.
CR (%) = − 5.9 × 10 ⁻⁴ × X ³ + 0.086 × X ² −4.0 × X + 100 (Approximation 1)
Here, X is the hydrogen concentration (vol%) in the gasified gas fuel. In this case, the standard deviation was 2.7%.

However, the function shown in FIG. 5 shows a minimum value at a certain hydrogen concentration, and shows a tendency that the conversion rate becomes higher when the hydrogen concentration becomes lower and higher than that. In explaining the physical phenomenon of the function shown in FIG. 5, it was considered appropriate to express the approximate expression as a function of the square of the hydrogen concentration. Therefore, the approximate expression was recalculated by the least square method to obtain the following expression.
CR = 0.02 × X ² −1.8 × X + 80 (Approximation 2)
The standard deviation in this case was 3.6%.

The cause of the deviation from the approximate expression 2 is considered to be an overlap between the presence of CO and N ₂ as components in the reaction gas and the experimental error.

As described above, the hydrogen concentration of the gasification gas fuel and the conversion rate of NH ₃ to NOx have a unique relationship regardless of the molar ratio of CO and H ₂ which are the main components of the gasification gas fuel. It became clear.

The results obtained in this example are as follows. The NH ₃ concentration in the gasified gas fuel is constant at 1000 ppmv, the CO / H ₂ molar ratio is in the range of 0.43 to 2.33, and the combustion average temperature is 1500. It is a result of analytically examining the physical relationship between the hydrogen concentration in the gasified gas fuel and the conversion rate of NH ₃ to NOx when the fuel heating value is changed under the condition of constant at 0 ° C. The correlation function can be obtained by the same method even when the conditions such as the combustion temperature and the NH ₃ concentration are other conditions.

However, when conditions such as the combustion temperature and NH ₃ concentration change, the physical relationship between the hydrogen concentration of the gasified gas fuel and the conversion rate of NH ₃ to NOx is maintained, but the gasified gas fuel Since the coefficient of the equation indicating the relationship between the hydrogen concentration and the conversion rate of NH ₃ to NOx changes, the relationship between the hydrogen concentration of the gasification gas fuel and the conversion rate of NH ₃ to NOx is shown in advance under the necessary conditions. By obtaining the equation, the conversion rate of NH ₃ to NOx at the combustor outlet can be predicted.

As described above, from the results of the present example, gasified gas fuel containing CO and H ₂ as main combustible components, a small amount of CH ₄ , and most of the remaining being CO ₂ , N ₂ and H ₂ O, for example, In a gasified gas fuel with a CH ₄ content of less than 0.1 vol%, the hydrogen concentration of the gasified gas fuel and the conversion rate of NH ₃ to NOx are the main components of the gasified gas fuel, CO and H It becomes clear that a unique relationship is shown regardless of the molar ratio of ₂ , and by utilizing this unique relationship, from the hydrogen concentration of the gasified gas fuel to the NOx of NH ₃ at the combustor outlet It became clear that the conversion rate could be predicted.

In the present embodiment, the nitrogen compound is NH ₃ , but even when the nitrogen compound is HCN, the hydrogen concentration of the gasification gas fuel and the conversion rate of HCN to NOx are the same as in the case of NH _3. DOO is irrespective of the molar ratio of CO and H ₂ is a major component of the gasification gas fuel, was estimated to exhibit unique relation.

That is, as a result of the analysis of the reactants, as in the case of NH ₃ , HCN is also oxidized to NOx, the decomposition start of NH _{3 and} the start of decomposition of HCN are led by OH, O, and H groups, OH and The amount of generation of O and H groups and the time during which the generation rate is increased depends on the reaction temperature, the reaction temperature at which OH, O and H groups are generated is the H ₂ component, and H in the air. _Since the diffusion coefficient of ₂ is more than four times that of CH ₄ and O ₂ , the hydrogen concentration of the gasification gas fuel and the conversion rate of HCN to NOx are similar to those of NH _3. regardless of the molar ratio of CO and H ₂ is the main component of which is estimated to exhibit a unique relation.

Accordingly, even when NH ₃ and HCN are contained in the nitrogen compound, it is estimated that there is a unique correlation between the hydrogen concentration of the gasification gas fuel and the conversion rate of the entire nitrogen compound into NOx. It was done.

(Example 2)
The relationship between the CO concentration of the combustion exhaust gas and the optimum reaction temperature for reducing NOx was examined from both numerical analysis and experiments.

  First, numerical analysis was performed to examine the influence of the CO concentration of the combustion exhaust gas on the reduction of NOx.

  For the numerical analysis, the elementary reaction scheme proposed by Millar and Bowman was used (literature name: Miller, JA, and Bowman, CT, 1989, “Mechanism and modeling of nitrogen chemistry in combustion,” Prog. Energy Combust. Sci. , Vol.15, pp.287-338.). The elementary reaction scheme of this document consists of 248 elementary reactions, and the chemical species considered are 50 components.

  As thermodynamic data, JANAAF thermodynamic property values were used, and unknown physical property values were derived from the relationship between Gibbs standard formation energy and chemical equilibrium constants. That is, 50 differential equations for obtaining the concentration of each chemical species with respect to the reaction time can be created from a chemical reaction equation system including 50 component chemical species. The concentration of each chemical species after an arbitrary reaction time was obtained by solving this 50-type nonlinear differential equation system using the Gear method. Also, in the reaction process, all chemical species are assumed to be uniformly mixed, diffusion and mixing processes are not considered, and the reaction proceeds at a constant temperature. The numerical method is not limited to the Gear method, and other numerical methods such as the Runge-Kutta method may be used.

  In general, since most of NOx is NO, numerical analysis was performed with NOx as NO.

The conditions for numerical analysis were as follows. That is, the reaction temperature was kept constant at 800 ° C., and the CO concentration was changed under the condition of supplying NH ₃ corresponding to 75 ppmv, which is half of the NO concentration of 150 ppmv. The CO ₂ and H ₂ O concentrations in the flue gas were about 13%, the O ₂ concentration was about 3%, and the remainder was adjusted with N ₂ gas. The CO concentration conditions of the combustion exhaust gas were 0, 50, and 100 ppmv.

  The results are shown in FIG. From this result, it became clear that when the CO concentration was changed from 0 ppmv to 100 ppmv, the reaction time was reduced to 1/10. That is, there was a tendency for the reaction rate to improve as the CO concentration increased.

Next, the relationship between the CO concentration of the combustion exhaust gas and the optimum reaction temperature for reducing NOx was examined by experiments. Put quartz tube in an electric furnace, mixed gas _{(NH 3: 0.1vol%, NO} : 0.1vol%, O 2: 0.5vol%, base gas: _{N 2)} was flowed into the quartz tube. Then, the temperature was lowered after holding 2.2 seconds was heated to 1000 ° C. in an electric furnace was measured mole fraction of the NH ₃ and NO. In addition, this experiment was performed for the case where CO was not circulated through the mixed gas (0 ppmv) and the case where CO was circulated 1000 ppmv.

The results are shown in FIG. In the case where no CO was circulated (0 ppmv), the lowest NH ₃ and NO molar fraction was around 900 ° C. Moreover, when 1000 ppmv of CO was circulated, the molar fraction of both NH ₃ and NO was lowest at around 800 ° C.

  From this experimental result, it was confirmed that the optimum reaction temperature shifts depending on the CO concentration, and that the optimum reaction temperature decreases as the CO concentration increases. In FIG. 7, the reason why the minimum value did not become 0 was examined by numerical analysis, and as a result, it became clear that it was caused by the process of raising the temperature of the mixed gas from room temperature to 1000 ° C.

  From the above, it has been found that in order to efficiently apply the gas phase denitration reaction represented by the chemical reaction formula 1, it is preferable to appropriately set the reaction temperature and the reaction time.

It is the schematic of 1st embodiment of the gasification power plant of this invention. It is the schematic of 2nd embodiment of the gasification power plant of this invention. It is the structure schematic of the combustor used in the present Example. It is a diagram showing a NOx conversion rate of the NH ₃ for higher heating value (HHV). Is a diagram showing the NOx conversion of NH ₃ to hydrogen concentration of the gasification gas fuel. It is a figure which shows the numerical analysis result about the influence of CO density | concentration which has on the non-catalytic denitration reaction in combustion exhaust gas. It is a figure which shows the result of having experimented about the relationship between CO density | concentration of combustion exhaust gas, and the optimal reaction temperature for reduce | restoring NOx.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification raw material 2 Gasifying agent 3 Gasification apparatus 4 Product gas 4a Gasification gas fuel 5 Gas purification apparatus 6 Combustion apparatus (gas turbine)
6a Gas Turbine Air Compressor 6b Gas Turbine Combustor 6c Gas Turbine Expansion Turbine 7 Generator 10 Reducing Agent 11 Computing Device 13 Reducing Agent Supplying Unit 13a Reducing Agent Supplying Unit 14 Controlling Unit 16 Storage Device 17 Hydrogen Concentration Measuring Device 18 CO Concentration measuring device FG Combustion exhaust gas (gas turbine exhaust gas)
G Combustion gas (gas turbine combustor exhaust gas)
A Combustion exhaust gas

Claims (9)

A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
A correlation function indicating the relationship between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained in advance.
Measure the hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value,
A NOx emission amount prediction method, wherein NOx concentration of combustion exhaust gas discharged from the combustion device is predicted based on the hydrogen concentration measurement value and the correlation function. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
A correlation function indicating the relationship between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained for each nitrogen compound concentration condition of the gasified gas fuel. Find in advance,
Measure the hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value,
Measuring the nitrogen compound concentration of the gasified gas fuel to obtain a nitrogen compound concentration measurement value,
Select the correlation function of the nitrogen compound concentration condition that fits the nitrogen compound concentration measurement,
A NOx emission amount prediction method for predicting a NOx concentration of combustion exhaust gas discharged from the combustion device based on the hydrogen concentration measurement value and the selected correlation function. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
A correlation function indicating the relationship between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained in advance.
Measure the hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value,
A predicted NOx concentration value of the flue gas discharged from the combustion device is obtained based on the measured hydrogen concentration value and the correlation function, and the amount of reducing agent supplied to the flue gas is determined according to the predicted NOx concentration value. An operation method of a gasification power plant characterized by controlling. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
A correlation function indicating the relationship between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained for each nitrogen compound concentration condition of the gasified gas fuel. Find in advance,
Measure the hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value,
Measuring the nitrogen compound concentration of the gasified gas fuel to obtain a nitrogen compound concentration measurement value,
Select the correlation function of the nitrogen compound concentration condition that fits the nitrogen compound concentration measurement,
A predicted NOx concentration value of the flue gas discharged from the combustion device is obtained based on the measured hydrogen concentration value and the selected correlation function, and the reducing agent to the flue gas is determined according to the predicted NOx concentration value. A method for operating a gasification power plant, characterized by controlling a supply amount. In the operation method of the gasification power plant according to claim 3 or 4,
Obtaining in advance the relationship between the optimum reaction temperature for the reduction of NOx in the flue gas and the CO concentration of the flue gas,
Measuring the CO concentration of the flue gas to obtain a CO concentration measurement value;
Based on the measured CO concentration value and the relationship, obtain an optimum predicted reaction temperature value,
A method for operating a gasification power plant, wherein the reducing agent is supplied to the combustion exhaust gas in a temperature range suitable for the predicted optimum reaction temperature. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
A storage device for storing a correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device;
A hydrogen concentration measuring device for measuring a hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value;
An arithmetic device for obtaining a NOx concentration calculation value of the combustion exhaust gas based on the hydrogen concentration measurement value and the correlation function;
Reducing agent supply means for supplying a reducing agent to the combustion exhaust gas;
A gasification power plant comprising: control means for controlling the amount of the reducing agent supplied from the reducing agent supply means based on the calculated NOx concentration. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
Correlation function obtained in advance for the correlation between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device, and reduction of NOx in the combustion exhaust gas A storage device for storing the optimum reaction temperature and the correlation between the CO concentration of the flue gas,
A hydrogen concentration measuring device for measuring a hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value;
A CO concentration measuring device for measuring the CO concentration of the flue gas to obtain a CO concentration measurement value;
An arithmetic unit that obtains a predicted NOx concentration value of the flue gas based on the measured hydrogen concentration value and the correlation function, and obtains an optimum predicted reaction temperature value based on the measured CO concentration value and the correlation;
A reducing agent supply means provided with a plurality of reducing agent supply units capable of supplying a reducing agent to a position where the temperature of the combustion exhaust gas is different;
The amount of the reducing agent supplied from the reducing agent supply means is controlled based on the predicted NOx concentration value and the predicted optimal reaction temperature value, and the optimal reaction temperature predicted value among the plurality of reducing agent supply units. A gasification power plant comprising: control means for selecting the reducing agent supply unit at a suitable position and supplying the reducing agent. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
The correlation between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained in advance for each nitrogen compound concentration of the gasified gas fuel. A storage device for storing the correlation function of
A hydrogen concentration measuring device for measuring a hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value;
A nitrogen compound concentration measuring device for measuring a nitrogen compound concentration of the gasified gas fuel to obtain a nitrogen compound concentration measurement value;
An arithmetic unit that selects the correlation function of the nitrogen compound concentration condition that matches the measured nitrogen compound concentration value, and obtains the calculated NOx concentration value of the combustion exhaust gas based on the measured hydrogen concentration value and the selected correlation function When,
Reducing agent supply means for supplying a reducing agent to the combustion exhaust gas;
A gasification power plant comprising: control means for controlling the amount of the reducing agent supplied from the reducing agent supply means based on the calculated NOx concentration. A gasification device that gasifies a gasification raw material with a gasifying agent to obtain a product gas; a gas purification device that purifies the product gas to obtain a gasification gas fuel; and the gasification gas fuel at a stoichiometric mixing ratio or less. In a gasification power plant comprising at least a combustion device that generates power by burning and a generator that generates power using the power,
The correlation between the hydrogen concentration of the gasified gas fuel and the conversion rate of nitrogen compounds contained in the gasified gas fuel into NOx in the combustion device is obtained in advance for each nitrogen compound concentration of the gasified gas fuel. A storage device that stores a correlation function of the above and a correlation between a reaction temperature optimum for the reduction of NOx in the combustion exhaust gas and a CO concentration of the combustion exhaust gas,
A hydrogen concentration measuring device for measuring a hydrogen concentration of the gasified gas fuel to obtain a hydrogen concentration measurement value;
A nitrogen compound concentration measuring device for measuring a nitrogen compound concentration of the gasified gas fuel to obtain a nitrogen compound concentration measurement value;
While selecting the correlation function of the nitrogen compound concentration condition that matches the nitrogen compound concentration measurement value, obtaining a predicted NOx concentration value of the combustion exhaust gas based on the hydrogen concentration measurement value and the selected correlation function, Further, an arithmetic device that obtains an optimum predicted reaction temperature value from the measured CO concentration value based on the correlation;
A reducing agent supply means provided with a plurality of reducing agent supply units capable of supplying a reducing agent to a position where the temperature of the combustion exhaust gas is different;
The amount of the reducing agent supplied from the reducing agent supply means is controlled based on the predicted NOx concentration value and the predicted optimal reaction temperature value, and the optimal reaction temperature predicted value among the plurality of reducing agent supply units. A gasification power plant comprising: control means for selecting a reducing agent supply unit at a suitable position and supplying the reducing agent.

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