Method for predicting water-cooling heat exchange steam yield of coal gasifier

Abstract

The invention discloses a method for predicting water-cooling heat exchange steam yield of a coal gasifier. The method comprises the following steps: establishing a heat exchange load mathematical model I for calculating a pyrolysis area of the coal gasifier and a heat exchange load mathematical model II for calculating a gasification area of the coal gasifier; establishing an energy balance mathematical model III of water-cooling heat exchange load of the coal gasifier and steam heat energy output by a steam pocket; parameters of the heat exchange load mathematical model I and the heat exchange load mathematical model II of the coal gasifier running in real time are obtained; parameters of a steam pocket running in real time are obtained; correcting the heat transfer coefficient of the water-cooled pipe in the pyrolysis area of the coal gasifier and the heat transfer coefficient of the water-cooled pipe in the gasification area of the coal gasifier; and predicting the water-cooling heat exchange load of the coal gasifier in real-time operation. According to the method, the calculation of the thermal load is combined into simulation software. According to the method, different calculation methods are adopted for calculation areas of models in different stages of pyrolysis and gasification of the water-cooled wall coil of the gasification furnace, and the problem that engineers cannot determine the thermal load of the water-cooled pipe for pyrolysis and gasification in the simulation process of the gasification furnace is solved.

Description

Technical Field

[0001] This application belongs to the technical field of heat transfer simulation calculation, and particularly relates to a method for predicting the steam output of a water-cooled heat exchanger in a gasifier. Background Art

[0002] The gasifier is the core equipment of the gasification plant, and the operating temperature of the gasifier cavity can reach up to 1400°C to 1800°C. The gasification process usually includes three parts: pyrolysis, gasification, and quenching. Among them, the reaction processes of the pyrolysis and gasification parts have relatively high operating temperatures and certain requirements for the ash fusion point. By adopting the water-cooling method, this problem can be solved, and at the same time, the heat can be recycled to produce steam.

[0003] However, when simulating the heat transfer of the water-cooled wall coil in the existing gasifier, the heat load is usually given according to operating experience. However, in the actual operation process of the factory, it is very difficult for engineers to accurately master the heat transfer load of the water-cooled wall. There is a general process simulation software Unisim internationally that can simulate the gasifier. When it comes to the heat transfer amount of the water-cooled wall, the user can only input the heat load.

[0004] Therefore, there is an urgent need to develop a method that can quantify the heat transfer load of the gasifier, so as to accurately cool the gasifier and convert the heat transfer amount into quantifiable steam for recycling. Summary of the Invention

[0005] The present invention calculates the heat transfer load for the method of recovering energy by generating high-temperature steam in the coil on the wall of the gasifier. In order to make the numerical calculation model of the gasifier adapt to the production operation requirements of gasification, the coil heat transfer area, heat transfer coefficient, water temperature and pressure are used as inputs. The coil heat transfer area and heat transfer coefficient can be obtained according to the equipment design parameters, and the operating temperature and operating pressure of the feed water can be read from the on-site instruments. Then, the heat load is obtained according to the heat transfer calculation. Compared with the value given by the engineer according to experience, the heat load calculated by the present invention is closer to the actual production. Moreover, the present invention proposes a method for calculating the heat transfer amount according to the coil heat transfer area, heat transfer coefficient, operating temperature and operating pressure of the feed water during the numerical simulation of the gasifier.

[0006] In view of the above technical problems, the technical solutions provided by the present invention are as follows.

[0007] A method for predicting the steam output of a water-cooled heat exchanger in a gasifier includes the following steps.

[0008] S1. Establish a mathematical model I for calculating the heat transfer load of the pyrolysis zone of the gasifier.

[0009] S11: Obtain the gasification temperature of the pyrolysis zone of the gasifier by simulating the coal pyrolysis and combustion processes through software .

[0010] S12: Calculate the saturation temperature of water using the IAPWS-IF97 formula based on the water pressure input by the user , and establish the heat transfer load mathematical model I

[0011] where is the heat transfer coefficient of the water-cooled pipe in the pyrolysis zone of the gasifier is the heat transfer area of the water-cooled pipe in the pyrolysis zone of the gasifier is the heat transfer load in the pyrolysis zone of the gasifier is the water supply inlet temperature of the water-cooled pipe in the pyrolysis zone of the gasifier is the water supply outlet temperature of the water-cooled pipe in the pyrolysis zone of the gasifier is the gasification temperature of coal pyrolysis

[0012] S2. Establish the heat transfer load mathematical model II for the gasification zone of the gasifier

[0013] S21: Divide the gasification zone of the gasifier axially into gasification zone chambers

[0014] S22: Sum up the heat transfer loads of all the gasification zone chambers of the gasifier to establish the heat transfer load mathematical model II

[0015] where is the height of the gasification zone of the gasifier is the height of the th chamber in the gasification zone of the gasifier is the heat transfer coefficient of the water-cooled pipe in the gasification zone of the gasifier is the heat transfer area of the water-cooled pipe in the gasification zone of the gasifier is the gasification temperature of the th chamber in the gasification zone of the gasifier is the saturation temperature of the water supply for the water-cooled pipe, which is also calculated according to the IAPWS-IF97 formula

[0016] S3. Based on the principle of energy conservation, establish the energy balance mathematical model III between the water-cooled heat transfer load of the gasifier and the steam thermal energy output by the steam drum

[0017] where is the molar flow rate of the recovered steam output by the steam drum is the molar vaporization enthalpy of the steam output by the steam drum

[0018] S4. Obtain the parameters of the heat transfer load mathematical model I and the heat transfer load mathematical model II of the gasifier operating in real time.

[0019] S5. Obtain the parameters of the steam drum operating in real time. The steam drum collects the high-temperature mixed steam output from the water-cooled pipes of the gasifier.

[0020] S6. Correct the heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the gasifier : Substitute the various parameters obtained in S4 and S5 into the energy balance mathematical model III, and perform iterative fitting calculations using the least squares method. Finally, calculate the corrected heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the gasifier .

[0021] S7. Predict the heat transfer load of the water-cooling of the gasifier operating in real time.

[0022] S71: Substitute the corrected heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the gasifier into the heat transfer load mathematical model I and the heat transfer load mathematical model II respectively.

[0023] S72: Add the heat transfer load of the pyrolysis zone of the gasifier calculated in S71 and the heat transfer load of the gasification zone of the gasifier to obtain the predicted value of the heat transfer load of the water-cooling of the gasifier operating in real time.

[0024] According to the embodiments of the present invention, the gasification temperature of coal in the entire pyrolysis zone of the gasifier is approximately constant.

[0025] According to the embodiments of the present invention, the water-cooled pipes in the gasification zone of the gasifier only approximately calculate the latent heat of water.

[0026] According to the embodiments of the present invention, the specific steps of S4 are as follows.

[0027] S41: Read the heat transfer area of the water-cooled pipes in the pyrolysis zone and the gasification zone of the gasifier and .

[0028] S42: Measure the water supply inlet temperature and the water supply outlet temperature of the water-cooled pipes in the pyrolysis zone of the gasifier.

[0029] S43: Set the height of each compartment in the mathematical model II, where , the gasification temperature of each compartment in the gasification zone of the gasifier is calculated using the Newton-Raphson method and the Jacobian matrix .

[0030] S44: Measure the water supply saturation pressure of the water-cooled pipe in the gasification zone of the gasifier .

[0031] S45: According to the water supply saturation pressure , look up the water supply saturation temperature of the water-cooled pipe in the gasification zone of the gasifier from the pressure-temperature conversion table of saturated water .

[0032] According to the embodiment of the present invention, the specific steps of S5 are as follows.

[0033] S51: Read the steam flow rate of the recovered steam output from the steam drum , and convert it into the molar flow rate of the recovered steam .

[0034] S52: Measure the steam outlet temperature and the steam outlet pressure of the steam drum, and calculate the corresponding molar enthalpy of vaporization of steam using the IAPWS-IF97 formula according to the steam outlet temperature and the steam outlet pressure . .

[0035] According to the embodiment of the present invention, the gasification temperature of the pyrolysis zone of the gasifier is obtained by simulating the coal pyrolysis process using the process simulation software SimTech Simulator .

[0036] According to the embodiment of the present invention, the water supply outlet temperature of the pyrolysis zone of the gasifier is set as the saturation temperature of the gasification pressure in the pyrolysis simulation software.

[0037] According to the embodiment of the present invention, the water-cooled pipes in the pyrolysis zone and the gasification zone of the gasifier are respectively separated into gas and liquid after entering the steam drum, and while outputting the recovered steam, fresh water is supplemented to maintain the mass balance of the system water.

[0038] According to the embodiment of the present invention, the heat transfer coefficient of the water-cooled pipe in the gasification zone of the gasifier and of the water-cooled pipe in the pyrolysis zone of the gasifier are corrected for reasons including but not limited to fouling and slagging on the inner wall of the gasifier water cooling.

[0039] According to the embodiment of the present invention, the gasifier performs water cooling independently in the pyrolysis zone and the gasification zone respectively.

[0040] The effects of the present invention are as follows.

[0041] 1. The input parameters of the numerical model of the gasifier in the present invention are changed from the heat load to the coil heat transfer area, heat transfer coefficient, water temperature, and water pressure. The heat load cannot be obtained through on-site instruments, while the coil heat transfer area, heat transfer coefficient, water flow rate, water temperature, and water pressure can be obtained from the design documents and on-site instruments. The present invention solves the problem that the heat load of pyrolysis and gasification cannot be determined by engineers during the simulation process of the gasifier, and combines the calculation of the heat load into the simulation software.

[0042] 2. The present invention adopts different calculation methods for the calculation regions of the pyrolysis and gasification different-stage models of the water-cooled wall coils of the gasifier.

[0043] 3. The present invention proposes a method for correcting the heat transfer coefficient of the water-cooled wall coils in the pyrolysis and gasification zones of the coal gasifier by reading the steam flow rate of the production device and the numerical simulation values. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flowchart of the method for predicting the steam production of the water-cooled heat exchange of the coal gasifier in the present invention.

[0045] Figure 2 is a schematic diagram of the process of water-cooled heat exchange steam of the coal gasifier in the present invention.

[0046] Figure 3 is a schematic diagram of the zoning of the gasification zone of the coal gasifier by the mathematical model II in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that the upper and lower limits of the range and each intermediate value between them are specifically disclosed. Each intermediate value within any stated value or stated range and each smaller range between any other stated value or intermediate value within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] The modeling and calculation process in the method for predicting the water-cooled heat exchange steam output of the gasifier of the present invention will be described in detail below.

[0050] In the water-cooled wall of an industrial water coal slurry gasifier device, there are usually two coils, which are respectively installed in the upper and middle parts of the furnace body. The inlets of the two coils are independent of each other, and the outlets of the two coils will be mixed in the steam drum to achieve gas-liquid equilibrium in the tank. The steam is sent as utility engineering to the utility engineering pipeline, and the liquid-phase water is mixed with fresh water and then sent back to the coil through the feed water pump to produce steam.

[0051] See Figure 2 , when the gasifier model is simulated, it is divided into three regions, namely pyrolysis, gasification, and quenching. According to the operation conditions of a certain factory, the present invention corresponds the pyrolysis and gasification regions to the two coils of the gasifier respectively. The pyrolysis region corresponds to the upper coil, and the gasification region corresponds to the middle coil.

[0052] See Figure 1 , the method for predicting the water-cooled heat exchange steam output of the gasifier of the present invention calculates and predicts the water-cooled heat exchange steam output of the gasifier by modeling and correcting the model. The specific process is as follows.

[0053] S1. Establish the heat transfer load mathematical model I for calculating the pyrolysis region of the gasifier.

[0054] S11: Obtain the gasification temperature of the pyrolysis region of the gasifier by simulating the coal pyrolysis and combustion processes through software , when water gas pyrolyzes in the pyrolysis region of the gasifier, the reaction heat of pyrolysis and combustion determines the gasification temperature of the pyrolysis region , the present invention obtains the gasification temperature of the pyrolysis region of the gasifier by simulating the coal pyrolysis process through the process simulation software SimTech Simulator independently developed by ShengTai . Calculate the gasification temperature of the pyrolysis region according to the principle of energy balance , when calculating the gasifier model, it is assumed to be completed instantaneously, so the gasification temperature of the entire pyrolysis region is regarded as the same temperature. This gasification temperature is obtained by calculating through software simulation of the pyrolysis process.

[0055] S12: According to the water pressure input by the user, use the IAPWS-IF97 formula to calculate the saturation temperature of water , and establish the heat transfer load mathematical model I.

[0056] The IAPWS-IF97 formula is divided into four formulas according to the temperature range. The IAPWS-IF97 formula combines the critical water region and the critical steam region into the critical region, combines the two saturated line regions into the saturated region, and adds a low-pressure high-temperature region. Since the present invention is related to the saturation temperature of the water-cooled outlet of the gasifier The region is at 273.15K ≤ T ≤ 623.15K, Ps ≤ P ≤ 100MPa, and the calculation is carried out relying on the code module of IAPWS-IF97. For specific code references, please refer to https: / / github.com / jjgomera / iapws.

[0057] The present invention uses a C# language development tool for programming calculations. Since the basic thermodynamic parameters that can be measured in the gasifier are the inlet pressure p and the inlet temperature T, the calculation program of the present invention uses p and T as known parameters to find the saturation temperature of the inlet water. .

[0058] is the logarithmic mean temperature difference of heat transfer between the fluids on both sides of the inlet and outlet of the gasifier. The logarithmic mean temperature difference is the logarithmic mean of the temperature differences at the cold end and the hot end in a double-pipe heat exchanger. The larger the logarithmic mean temperature difference, the greater the heat transfer. The logarithmic mean temperature difference appears when analyzing heat exchangers with fixed flow rates and fluid thermodynamic properties. In the gasifier, when there are phase changes in the fluids on both sides of the inlet and outlet, the gasification temperature in the pyrolysis zone of the gasifier remains unchanged, and this heat transfer is called constant temperature difference heat transfer. is the temperature difference at the inlet, is the temperature difference at the outlet.

[0059] (1) (2) (3) After determining the logarithmic mean temperature difference in the pyrolysis zone of the gasifier, calculate the heat load in the pyrolysis zone according to the basic heat transfer equation (4) (4) After substituting and arranging equations (1), (2), (3) and (4), the following equation is obtained, that is, the heat transfer load mathematical model I:

[0060] Where is the heat transfer coefficient of the water-cooled pipe in the pyrolysis zone of the gasifier, is the heat transfer area of the water-cooled pipe in the pyrolysis zone of the gasifier, is the heat transfer load in the pyrolysis zone of the gasifier, is the water supply inlet temperature of the water-cooled pipe in the pyrolysis zone of the gasifier input by the user, is the water supply outlet temperature of the water-cooled pipe in the pyrolysis zone of the gasifier, is the gasification temperature of coal pyrolysis.

[0061] S2. Establish the heat transfer load mathematical model II for calculating the gasification zone of the gasifier.

[0062] S21: Divide the gasification zone of the gasifier along the axial direction into gasification zone chambers.

[0063] See Figure 3 , the temperature of the gasification zone is the highest and the length is longer. In software simulation, it will be divided into multiple chambers and calculated one by one from top to bottom. Since the latent heat of water is much larger than the sensible heat, taking 1 mol of water heated from room temperature of 25 °C to 100 °C as an example, the heat load of sensible heat is 5.66 kJ / mol, and the heat load of latent heat is 40.65 kJ / mol. The latent heat is more than 7 times that of sensible heat. The temperature of each chamber in the gasification zone is different and forms a countercurrent with water. If calculated by logarithmic temperature difference, nested iterative calculations will be formed. The heat load itself is an auxiliary function, which will increase the calculation amount of the gasifier. Since the latent heat of water is significantly greater than the sensible heat, a simplified method is adopted, only calculating the latent heat and assuming that the temperature of water is constant, which is the saturation temperature at the current pressure.

[0064] S22: Sum up the heat transfer loads of all gasification zone chambers of the gasifier to establish a mathematical model of heat transfer load , divide the gasification zone of the gasifier with a total height of into chambers. The heat transfer temperature difference of each chamber is the gasification temperature of this chamber minus the saturation temperature of water at the current pressure. Calculate the heat load of each chamber respectively, and the total heat transfer load of the gasification zone is obtained after accumulation, that is, the mathematical model of heat transfer load

[0065] Where is the height of the gasification zone of the gasifier, is the height of the th chamber in the gasification zone of the gasifier, is the heat transfer coefficient of the water-cooled pipe in the gasification zone of the gasifier, is the heat transfer area of the water-cooled pipe in the gasification zone of the gasifier, is the gasification temperature of the th chamber in the gasification zone of the gasifier, is the supply saturation temperature of the water-cooled pipe, which is also calculated according to the IAPWS-IF97 formula.

[0066] S3. According to the principle of energy conservation, establish an energy balance mathematical model III of the water-cooled heat transfer load of the gasifier and the steam heat energy output by the steam drum,

[0067] Where is the molar flow rate of the recovered steam output by the steam drum, is the molar vaporization enthalpy of the steam output by the steam drum.

[0068] During the actual production process, the heat transfer coefficients in the pyrolysis zone and gasification zone of the gasifier will change due to fouling, slagging on the inner wall, etc. After the device has been operating for a period of time, it is necessary to correct the heat transfer coefficients and This invention can correct multiple sets of historical data. The correction variables are and , and the energy balance equation needs to be satisfied. According to multiple sets of historical data, the least squares method is used for fitting.

[0069] It should be noted that the water-cooled pipes in the pyrolysis zone and gasification zone of the gasifier enter the steam drum respectively for gas-liquid separation. While outputting the recycled steam, fresh water is supplemented to maintain the mass balance of the system water.

[0070] It should be noted that the heat transfer coefficient of the water-cooled pipe in the gasification zone of the gasifier and that of the water-cooled pipe in the pyrolysis zone of the gasifier The reasons for correction include, but are not limited to, fouling of the water cooling of the gasifier and slagging on the inner wall.

[0071] It should be noted that the water cooling in the pyrolysis zone and gasification zone of the gasifier is carried out independently.

[0072] S4. Obtain the parameters of the heat transfer load mathematical model I and heat transfer load mathematical model II of the gasifier operating in real time. The specific steps are as follows.

[0073] S41: Read the heat transfer areas and of the water-cooled pipes in the pyrolysis zone and gasification zone of the gasifier.

[0074] S42: Measure the water supply inlet temperature and water supply outlet temperature of the water-cooled pipes in the pyrolysis zone of the gasifier.

[0075] S43: Set the height of each compartment in the mathematical model II, where , is the gasification temperature of each compartment in the gasification zone of the gasifier. Calculations are carried out relying on simulation software, and its temperature is related to the reaction conditions inside the gasifier.

[0076] S44: Measure the water supply saturation pressure of the water-cooled pipes in the gasification zone of the gasifier.

[0077] S45: According to the water supply saturation pressure , use the IAPWS-IF97 formula to calculate the water supply saturation temperature , the calculation method is as described in S12.

[0078] S5. Obtain the parameters of the steam drum in real-time operation. The steam drum collects the high-temperature mixed steam output from the water-cooled pipes of the coal gasifier, specifically including the following.

[0079] S51: Read the steam flow rate of the recovered steam output from the steam drum , and convert it into the molar flow rate of the recovered steam . The molar flow rate of the recovered steam can be calculated through the formula where is the standard molar volume of gas, 22.414 L / mol.

[0080] S52: Measure the steam outlet temperature of the steam drum and the steam outlet pressure . The calculation program calculates the corresponding molar enthalpy of vaporization of the steam according to the IAPWS-IF97 formula .

[0081] S6. Correct the heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the coal gasifier: Substitute the various parameters obtained in S4 and S5 into the energy balance mathematical model III, and use the least squares method for iterative fitting calculation. Finally, calculate the corrected heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the coal gasifier .

[0082] In the actual production process, multiple sets of and the obtained by simulation can be obtained. Among them, . For multiple sets of , in order to solve the corrected heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the coal gasifier , continuously change and try the heat transfer coefficient to minimize the objective function . where: The

[0083] that minimizes the objective function

[0084]

[0085] is the corrected heat transfer coefficient of the water-cooled pipes in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipes in the gasification zone of the coal gasifier .

[0086] is the heat transfer amount at the top outlet of the on-site steam drum, and is the steam amount read by the flow meter for actual production. Through the formula

[0087] where is the molar flow rate of the recovered steam output from the steam drum, is the molar enthalpy of vaporization of the steam output from the steam drum.

[0088] S7. Predict the heat transfer load of the water cooling of the coal gasifier in real-time operation, which specifically includes the following.

[0089] S71: Substitute the corrected heat transfer coefficient of the water-cooled pipe in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water-cooled pipe in the gasification zone of the coal gasifier into the heat transfer load mathematical model I and the heat transfer load mathematical model II respectively. At this time, both heat transfer load mathematical models I and II are corrected by the heat transfer coefficient, and the heat transfer load of the water cooling of the coal gasifier in real-time operation can be predicted according to the actual operation conditions of the pyrolysis zone and the gasification zone of the coal gasifier. The advantage of this correction method is that the operation data of the water cooling of the coal gasifier in real-time operation and the instrument data of the coal gasifier can be input during any period considered appropriate by the user, and then the heat transfer load mathematical model can be calibrated to monitor the water cooling efficiency of the coal gasifier in real-time.

[0090] S72: Add the heat transfer load of the pyrolysis zone of the coal gasifier calculated in S71 and the heat transfer load of the gasification zone of the coal gasifier to obtain the predicted value of the heat transfer load of the water cooling of the coal gasifier in real-time operation. In actual operation, the steam amount at the top outlet of the on-site steam drum is read by the flow meter. The error between the predicted value of the heat transfer load of the water cooling of the coal gasifier and the steam amount obtained by reading the flow meter at the top outlet of the on-site steam drum is within 5%, which is acceptable in industry.

[0091] An embodiment of the method for predicting the water-cooled heat exchange steam output of a coal gasifier is as follows. First, the analytical and test data of coal are input into SimTech Simulator to characterize the coal. Then, the instrument data of coal, water, carrier gas, oxygen, and quench water in the water-to-steam module read are input into the software, including flow rate, temperature, and pressure. Next, the water temperature, water pressure, heat transfer coefficient, and heat transfer area in the water-cooled pyrolysis zone and gasification zone of the coal gasifier are read, and these data are also input into SimTech Simulator for simulation calculation. Finally, after all the above data are input into SimTech Simulator, the process simulation calculation is started. This simulation process will correct the heat transfer coefficient, thereby correcting the mathematical model of the heat transfer load. Therefore, the final output of SimTech Simulator is the simulated value of the water-cooled heat exchange steam output of the coal gasifier, that is, its predicted value. At this time, the calculation results of the water-cooled part of the coal gasifier can be obtained in SimTech Simulator, including the heat load and steam volume in the pyrolysis zone and gasification zone. The steam volumes in the pyrolysis zone and gasification zone are added up and compared with the steam volume at the top outlet of the steam drum read by the on-site flowmeter to evaluate the accuracy of the water-cooled part of the coal gasifier.

[0092] Example 1 Adopt the water-cooled wall cold water to steam module 1 of the coal gasifier, and the relevant parameters are as follows.

[0093] Table 1 Physical properties of coal in the water-to-steam module 1

[0094] The coal composition obtained according to the physical properties of coal is C 0.77357 H 0.6011 N 0.00854 O 0.09998 S 0.00147 Cl 0 Dust 0.01656 。

[0095] Table 2 Feed parameters of the water-to-steam module 1

[0096] Table 3 Reaction-related parameters in the pyrolysis zone and gasification zone of the calculated gasifier

[0097] Based on the above data, the user can build a model in the process simulation software SimTech Simulator and perform simulation calculations to obtain the heat loads of the pyrolysis zone and gasification zone of the gasifier, which are -6.19e+5 kW and -7.52e+6 kW respectively. The corresponding steam flow can be calculated through the known evaporation enthalpy of water, and the steam flow measured by the flowmeter at the top outlet of the on-site steam drum is 3.73 t / h. The data comparison is shown in the following table.

[0098] Table 4 Calculated Heat Load and Steam Flow

[0099] Through this method, when the user cannot estimate the heat loads of the pyrolysis and gasification zones of the gasifier, the total steam flow (3.61 t / h) calculated by the simulation software is relatively close to the actual steam flow (3.73 t / h) produced, with an error within 5%. Example 2

[0100] Adopt the steam generation module 2 of the water-cooled wall of the gasifier, and the relevant parameters are as follows.

[0101] Table 5 Physical Properties of Coal for the Steam Generation Module 2 with Water

[0102] The coal composition obtained according to the physical properties of coal is C 0.72349 H 0.46481 N 0.00557 O 0.12534 S 0.00268 Cl 0.00016 Dust 0.02065 .

[0103] Table 6 Feed Parameters of the Steam Generation Module 2 with Water

[0104] Table 7 Reaction-Related Parameters of the Pyrolysis Zone and Gasification Zone of the Gasifier Calculated

[0105] Based on the above data, the user can build a model in the process simulation software SimTech Simulator and perform simulation calculations to obtain the heat loads of the pyrolysis zone and gasification zone of the gasifier, which are -6.4345e+5 kJ / h and -4.7886e+7 kJ / h respectively. The corresponding steam flow can be calculated through the known evaporation enthalpy of water, and the steam flow measured by the flowmeter at the top outlet of the on-site steam drum is 23.012 t / h. The data comparison is shown in the following table.

[0106] Table 8 Calculated Heat Load and Steam Flow

[0107] Through this method, when the user is unable to estimate the heat loads of the pyrolysis zone and the gasification zone of the gasifier, the total steam flow rate (22.426 t / h) calculated by the simulation software is relatively close to the actually produced steam flow rate (23.012 t / h), with an error within 5%. Example 3

[0108] The water-cooled wall cold water steam generation module 3 of the coal gasifier is adopted, and the relevant parameters are as follows.

[0109] Table 9 Physical properties of coal for the water steam generation module 3

[0110] The coal composition obtained based on the physical properties of coal is C 0.72349 H 0.46481 N 0.00557 O 0.12534 S 0.00268 Cl 0.00016 Dust 0.02065 .

[0111] Table 10 Feed parameters of the water steam generation module 3

[0112] Table 11 Calculated reaction-related parameters of the pyrolysis zone and the gasification zone of the gasifier

[0113] Based on the above data, the user can build a model and perform simulation calculations in the process simulation software SimTech Simulator, and obtain the heat loads of the pyrolysis zone and the gasification zone of the coal gasifier as -7.1047e+7 kJ / h and -3.7058e+7 kJ / h respectively. The corresponding steam flow rate can be calculated through the known enthalpy of vaporization of water, and the steam flow rate read from the flowmeter at the top outlet of the on-site steam drum is 51.23 t / h. The data comparison is shown in the following table.

[0114] Table 12 Calculated heat loads and steam flow rates

[0115] Through this method, when the user is unable to estimate the heat loads of the pyrolysis zone and the gasification zone of the gasifier, the total steam flow rate (50.52 t / h) calculated by the simulation software is relatively close to the actually produced steam flow rate (51.23 t / h), with an error within 5%.

[0116] As can be seen from the above, the method for predicting the water-cooled heat exchange steam output of a coal gasifier has its independent simulation and calculation methods, and the simulation and calculation are carried out based on the SimTech Simulator software independently developed by the applicant. By reading the steam flow rate of the production device and the simulation values of the SimTech Simulator software, the heat transfer coefficient of the water-cooled wall coil in the pyrolysis and gasification sections of the coal gasifier is corrected. The conventional operation in the field of water cooling of coal gasifiers is to provide the heat load based on the experience of technicians, which requires high experience of practitioners and cannot predict the real-time changing water-cooling process of coal gasifiers in a timely and efficient manner. However, in the present invention, the heat exchange load is changed to be calculated based on the known coil heat exchange area, heat transfer coefficient, water temperature and pressure. The heat load cannot be obtained through on-site instruments, while the coil heat exchange area, heat transfer coefficient, water flow rate, water temperature and pressure can be obtained from the design documents and on-site instruments. In this way, data can be conveniently input into the SimTech Simulator software in real time, changing the experience of technicians into data processing of the model, and the accuracy and timeliness of the water-cooled heat exchange steam output of the coal gasifier are higher and better.

[0117] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. Various adjustments or changes can be made to the exemplary embodiments of the present invention specification without departing from the scope or spirit of the present invention. The scope of the claims should be interpreted based on the broadest interpretation to cover all modifications and equivalent structures and functions.

Claims

1. A method for predicting the water-cooled heat exchange steam output of a coal gasifier, comprising: S1. Establishing a mathematical model I for calculating the heat exchange load of the pyrolysis zone of the coal gasifier: S11: The gasification temperature of the pyrolysis zone of the coal gasifier is obtained by simulating the coal pyrolysis and combustion process through software ; S12: Calculate the saturated temperature of water using the IAPWS-IF97 formula based on the water pressure input by the user , establish the heat transfer load mathematical model I, ， in is the heat transfer coefficient of the water cooling tube in the pyrolysis zone of the coal gasifier, is the heat exchange area of ​​the water cooling tube in the pyrolysis zone of the coal gasifier, is the heat exchange load of the pyrolysis zone of the coal gasifier, is the water supply inlet temperature of the water cooling pipe in the pyrolysis zone of the coal gasifier, is the outlet temperature of the water supply to the water cooling pipe in the pyrolysis zone of the coal gasifier, is the gasification temperature of coal pyrolysis, S2. Establishing a mathematical model II for calculating the heat exchange load of the gasification zone of the coal gasifier: S21: Divide the gasification zone of the coal gasifier into Gasification compartment; S22: summing up the heat exchange loads of all the gasification chambers of the coal gasifier to establish the heat exchange load mathematical model II. ， in is the height of the gasification zone of the coal gasifier, The first the height of the compartment, is the heat transfer coefficient of the water-cooling tube in the gasification zone of the coal gasifier, is the heat exchange area of ​​the water cooling tube in the gasification zone of the coal gasifier, The first gasification zone in the coal gasifier The vaporization temperature of each of the compartments, is the water supply saturation temperature of the water cooling pipe, which is also calculated according to the IAPWS-IF97 formula. S3. According to the energy conservation principle, an energy balance mathematical model III of the water-cooling heat exchange load of the coal gasifier and the steam heat energy output by the steam drum is established. ， in is the molar flow rate of the recovered steam output from the steam drum, is the molar enthalpy of vaporization of the steam output from the steam drum, S4, obtaining parameters of the heat exchange load mathematical model I and the heat exchange load mathematical model II of the coal gasifier in real-time operation, S5. Obtaining parameters of a steam drum in real-time operation, wherein the steam drum collects high-temperature mixed steam outputted by the water-cooling pipe of the coal gasifier, S6. The heat transfer coefficient of the water cooling tube in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water cooling tube in the gasification zone of the coal gasifier Correction: Substitute the various parameters obtained in S4 and S5 into the energy balance mathematical model III, use the least squares method to perform iterative fitting calculations, and finally calculate the corrected heat transfer coefficient of the water cooling tube in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water cooling tube in the gasification zone of the coal gasifier , S7. Predict the heat exchange load of the water cooling of the coal gasifier in real-time operation: S71: The corrected heat transfer coefficient of the water cooling tube in the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water cooling tube in the gasification zone of the coal gasifier are respectively substituted into the heat exchange load mathematical model I and the heat exchange load mathematical model II; S72: The heat exchange load of the pyrolysis zone of the coal gasifier calculated in S71 is and the heat exchange load of the gasification zone of the coal gasifier Add them together to get the predicted value of the heat exchange load of the water cooling of the coal gasifier in real time operation.

2. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the gasification temperature of the coal in the entire pyrolysis zone of the coal gasifier is approximately constant.

3. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the water-cooling pipes in the gasification zone of the coal gasifier only approximately calculate the latent heat of water.

4. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the specific steps of S4 are: S41: Obtaining the heat exchange area of ​​the water cooling pipe in the pyrolysis zone of the coal gasifier and the gasification zone of the coal gasifier and ; S42: Measuring the water supply inlet temperature of the water cooling pipe in the pyrolysis zone of the coal gasifier and the water supply outlet temperature ; S43: Setting the height of each compartment in the mathematical model II ,in , using the Newton-Raphson method and the Jacobian matrix to calculate the gasification temperature of each of the chambers in the gasification zone of the coal gasifier ; S44: Measuring the water supply saturation pressure of the water cooling pipe in the gasification zone of the coal gasifier ; S45: According to the water supply saturation pressure , use IAPWS-IF97 formula to calculate the water supply saturation temperature of the water cooling pipe in the gasification zone of the coal gasifier .

5. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the specific step of S5 comprises: S51: Read the steam flow rate of the recovered steam output from the steam drum , converted into the molar flow rate of the recovered steam ; S52: Measure the steam outlet temperature of the steam drum and steam outlet pressure , according to the steam outlet temperature and the steam outlet pressure Use the IAPWS-IF97 formula to calculate the corresponding steam molar enthalpy of vaporization .

6. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the process simulation software SimTech Simulator is used to simulate the coal pyrolysis process to obtain the gasification temperature of the pyrolysis zone of the coal gasifier. .

7. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 6, wherein the outlet temperature of the water supply to the pyrolysis zone of the coal gasifier is The saturation temperature of the vaporization pressure was set in the pyrolysis simulation software.

8. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the water-cooling pipes in the pyrolysis zone and the gasification zone of the coal gasifier enter the steam drum respectively for gas-liquid separation, and while outputting the recovered steam, fresh water is added to the steam drum to maintain the mass balance of water in the system.

9. The method for predicting the water cooling heat exchange load of a coal gasifier according to claim 1, wherein the water cooling pipe of the pyrolysis zone of the coal gasifier and the heat transfer coefficient of the water cooling tube in the gasification zone of the coal gasifier The reasons for the correction include but are not limited to scaling of the water cooling of the coal gasifier and slag hanging on the inner wall.

10. The method for predicting the water-cooled heat exchange steam production of a coal gasifier according to claim 1, wherein the coal gasifier is independently water-cooled in the pyrolysis zone and the gasification zone.

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