A Simulation and Optimization Method for the Process of Co-Disposing Organic Solid Wastes in a Cement Kiln

Abstract

The invention belongs to the field of solid waste treatment and disposal, and discloses a simulation and optimization method for a process of co-disposing organic solid waste in a cement kiln, comprising the following steps: S1 Using Aspen Plus software, select physical property methods and chemical components; S2 Establish a steady-state process simulation model; S3 According to the feed parameters in the production process, input them into the model to obtain calculation results; S4 Compare the calculation results with the measured values in the production process. If the acceptance limit requirements are not met, adjust the operation unit parameters in the steady-state process simulation model; S5 Input the feed parameters corresponding to the improved process into the model to obtain calculation results, and then judge whether to adjust the improved process, so as to achieve process optimization. The invention uses a steady-state process simulation model designed with specific subsystems and streams, providing an effective tool for the process design of co-disposing organic solid waste in a cement kiln, reducing the trial operation cost and improving the work efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of solid waste treatment and disposal, and more specifically, relates to a method for simulating and optimizing the process of co-disposing organic solid waste in a cement kiln. Background Art

[0002] Social activities and industrial production generate organic solid wastes such as domestic garbage, municipal sludge, and traditional Chinese medicine residues. At present, the mainstream methods for treating organic solid waste are landfill, incineration, composting, etc. Among them, the incineration technology can quickly realize the harmlessness and reduction of organic solid waste. Compared with a single organic solid waste incineration device, using the existing cement kiln to co-dispose organic solid waste can reduce the construction investment of the incineration device. At the same time, the incineration ash residue of organic solid waste and cement raw meal are jointly fired into cement clinker, eliminating the hazardous waste treatment process and avoiding the risk of secondary pollution, and realizing the complete resource utilization of organic solid waste.

[0003] Some cement enterprises have transformed their existing cement production lines for co-disposing organic solid waste. However, different organic solid wastes vary greatly in properties such as moisture content, calorific value, and elemental composition. Cement enterprises mostly increase or decrease the dosage of organic solid waste according to the quality of clinker and gas monitoring data, but this method has a long time lag, high trial operation cost, and long exploration cycle. Therefore, using software to simulate the actual production process of a cement kiln and study the energy change and material change in the cement kiln system is an effective method. Aspen Plus is a large-scale general process simulation system applied to the design of production devices, steady-state simulation, and optimization of process processes in industrial processes, mostly used in the fields of petrochemical and coal chemical industries, and less used in the cement industrial system, especially in the field of co-disposing organic solid waste in a cement kiln.

[0004] In the master's thesis "Analysis of Air Pollution Emissions and Energy Utilization in the Cement Precalciner Kiln Process Based on Aspen Plus" in 2010, Cao Shenxue established a steady-state process model for the suspension preheater, decomposing kiln, and rotary kiln in the cement kiln system. The partial decomposition process of raw meal in the preheater was not considered in the model, and the key technology bypass air release system for co-processing in cement kilns was not included. Considering the entire cement clinker firing model as an adiabatic environment also does not conform to the actual production conditions. The model mainly optimizes the traditional cement production process and has little exploration of the co-processing of organic solid wastes in cement kilns. The sensitivity analysis module used to analyze alternative fuels can only analyze fixed-ratio mixed fuels. After modifying the ratio, the relevant parameters of the mixed fuel need to be manually calculated first, and then the original coal stream needs to be replaced, and the flexible ratio of any organic solid waste cannot be achieved. In the master's thesis "Research on the System of Co-processing Municipal Solid Waste in Cement Kilns" in 2016, Dong Zhen used Aspen Plus to establish a process model for co-disposing municipal solid waste in a waste incinerator and a cement rotary kiln. However, the essence of the process is that waste incineration and cement firing are carried out separately, and there are also some unreasonable assumptions, such as only considering a single organic solid waste, municipal solid waste. In the master's thesis "Simulation and Analysis of Phosphogypsum-based Acid Production and Co-production of Cement Based on Aspen Plus" in 2018, in the model established by Xia Nuo, only phosphogypsum was studied as a part of the raw meal, and the relevant processes of co-processing organic solid wastes in cement kilns were not involved. In the journal paper "Research on NOx Generation Simulation and Emission Reduction Optimization in Cement Kiln Furnaces Based on Aspen Plus", Liu Dingping and others only modeled the precalciner and rotary kiln in the traditional cement production process and studied the NOx emission process, and similarly did not involve the research on co-processing organic solid wastes in cement kilns. Chinese invention patent (publication number CN103400196B) discloses a modeling and optimization method for clean production in the cement clinker firing process. Chemical reaction kinetics is used to describe the fuel combustion and raw meal decomposition processes in the established model. However, the combustion process is extremely complex, and the chemical reaction kinetics calculation for each type of combustion product greatly increases the calculation amount. At the same time, the model calculates the combustion process and the gas-solid heat transfer process separately, ignoring the influence of environmental temperature on the existing form of combustion products. Although the addition of a process module for co-processing organic solid wastes (municipal solid waste) in cement kilns is involved in the model, for the mixing of multiple organic solid wastes, the properties and energy of the mixture need to be manually calculated first, and then the mixed fuel stream is used to replace the original fuel stream. Each time the mixing ratio is changed, it needs to be recalculated manually, which is not conducive to the research on co-processing organic solid wastes in cement kilns.

[0005] In summary, there are few simulation studies on the co - disposal of organic solid waste in cement kilns using Aspen Plus at present. Moreover, there are still some unreasonable assumptions in the existing models, such as ignoring environmental heat transfer and lacking relevant process modules. At the same time, the existing models mostly focus on single organic solid waste with fixed properties. The organic solid waste can only be mixed according to a fixed ratio, and the input parameters such as the elemental composition and calorific value of the mixed organic solid waste are calculated manually, which is rather cumbersome. In actual production, the physical and chemical properties of the organic solid waste co - disposed in the cement kiln vary greatly in terms of type, quality, moisture content, element proportion, calorific value, etc. The co - firing ratio of different types of organic solid waste in the cement kiln will be dynamically adjusted according to production requirements at any time. The existing models cannot explore the impact of changes in the properties of organic solid waste on core processes such as the temperature change of the cement kiln or the law of flue gas emissions. Therefore, there is still a need for a model for the co - disposal of organic solid waste in cement kilns, which can accurately and conveniently perform simulation calculation and analysis on the core process units during the process of the cement kiln system co - disposing of organic solid waste, such as the temperature change of the decomposition furnace, flue gas emissions, mass balance, and energy balance, etc., so as to provide theoretical data for the optimization of the co - disposal process of the cement kiln. Summary of the Invention

[0006] Aiming at the above - mentioned defects or improvement requirements of the existing technology, the purpose of the present invention is to provide a method for simulating and optimizing the process of co - disposing organic solid waste in a cement kiln. By using Aspen Plus software to establish a steady - state process simulation model, and by setting up 4 subsystems, namely the suspension preheater subsystem, the decomposition furnace subsystem, the rotary kiln subsystem, and the organic solid waste decomposition subsystem in the simulation model, and cooperating with material streams and heat streams, it is possible to perform simulation calculation and analysis on the core process units during the process of the cement kiln system co - disposing of organic solid waste, such as the temperature change of the decomposition furnace, flue gas emissions, mass balance, and energy balance, etc. Combining with the actual requirements of the improved process, it can effectively predict the improved process, and then provide a basis for whether the improved process meets the expectations and whether adjustment is needed, so as to realize process optimization. The method of the present invention provides an effective tool for the process design of co - disposing organic solid waste in a cement kiln, reducing the trial - operation cost and improving the work efficiency.

[0007] To achieve the above object, according to the present invention, there is provided a method for simulating and optimizing the process of co - disposing organic solid waste in a cement kiln, characterized by including the following steps:

[0008] (S1) Using Aspen Plus software, select the physical property method used in the software calculation, and at the same time select the conventional components and solid - phase components involved in the software calculation, and take the other pre - selected components as unconventional components, and newly create the unconventional components involved in the software calculation;

[0009] (S2) Establish a steady-state process simulation model, which includes several subsystems. Each subsystem includes streams and several operation units; the various subsystems are interconnected through streams; these subsystems include:

[0010] Suspension preheater subsystem: used to correspond to the suspension preheater equipment in cement production, and the streams therein are arranged according to the flow directions of gas and solid in the cement production process;

[0011] Calciner subsystem: used to correspond to the calciner equipment in cement production, including the operation unit corresponding to raw meal decomposition and the operation unit corresponding to combustion reaction; the streams in this calciner subsystem are set to first pass through the operation unit corresponding to raw meal decomposition in the calciner subsystem and then pass through the operation unit corresponding to combustion reaction in the calciner subsystem; among them, the operation unit corresponding to combustion reaction is the Gibbs reactor (RGibbs) operation unit;

[0012] Rotary kiln subsystem: used to correspond to the rotary kiln equipment in cement production, including the operation unit corresponding to raw meal decomposition and the operation unit corresponding to combustion reaction; the streams in this rotary kiln subsystem are set to first pass through the operation unit corresponding to raw meal decomposition in the rotary kiln subsystem and then pass through the operation unit corresponding to combustion reaction in the rotary kiln subsystem; among them, the operation unit corresponding to combustion reaction is the Gibbs reactor operation unit;

[0013] Organic solid waste decomposition subsystem: used to correspond to the decomposition process of organic solid waste in the calciner equipment and rotary kiln equipment in cement production, and the streams therein are set according to the physical and chemical reaction processes of drying and pyrolysis in sequence;

[0014] The steady-state process simulation model also includes: a calculator module, a design specification module, and a sensitivity analysis module, where:

[0015] The calculator module: used to control the calculation process of each operation unit;

[0016] The design specification module: used to control a certain variable in this steady-state process simulation model to make it a specified value or a specified range;

[0017] The sensitivity analysis module: used to cooperate with the design specification module to make a certain variable change within a specified range at a preset step size;

[0018] (S3) According to the feed parameters in the production process, input these feed parameters into the corresponding streams in the steady-state process simulation model obtained in step (S2) for simulation, and through the calculation of the model, obtain the calculation results of each subsystem;

[0019] The feed parameters include both the types of feed streams and the parameters of the feed streams; among them, the types of feed streams include different raw materials, different fuels, and air fed into the cement kiln; the parameters of the feed streams include mass flow rate, temperature, and chemical composition;

[0020] The calculation results include temperature, flow rate, and composition;

[0021] (S4) Compare the calculation results obtained in step (S3) with the measured values during the production process. If the relative error exceeds the pre-selected acceptance limit value, modify the operation unit parameters in the steady-state process simulation model in step (S2), and repeat steps (S3) and (S4) until the relative error does not exceed the pre-selected acceptance limit value;

[0022] (S5) Based on the pre-selected improved process, input the feed parameters corresponding to the improved process into the steady-state process simulation model. Through the calculation of the model, obtain the calculation results of each subsystem; based on the calculation results, determine whether to adjust the improved process to achieve process optimization.

[0023] As a further preference of the present invention, step (S5) specifically includes the following sub-steps:

[0024] (S5-1) Establish an interactive interface, and link the streams and the sensitivity analysis module in the steady-state process simulation model to the interactive interface respectively;

[0025] (S5-2) Based on the pre-selected improved process, input the feed parameters corresponding to the improved process into the steady-state process simulation model through the interactive interface for simulation. Through the calculation of the model, obtain the calculation results of each subsystem; based on the calculation results, determine whether to adjust the improved process to achieve process optimization.

[0026] As a further preference of the present invention, in step (S2), the suspension preheater subsystem is divided into five levels, C1-C5, from top to bottom. The four processes of gas-solid mixed heat transfer, carbonate decomposition, surface heat dissipation, and gas-solid separation occurring in the suspension preheater equipment in cement production are respectively realized by the mixer operation unit, the stoichiometric reactor operation unit, the heater operation unit, and the SSplit operation unit; among them, the C1 level includes the mixer operation unit, the heater operation unit, and the SSplit operation unit connected in sequence by material streams; each of the C2-C4 levels includes the mixer operation unit, the stoichiometric reactor operation unit, the heater operation unit, and the SSplit operation unit connected in sequence by material streams; the C5 level includes the heater operation unit and the SSplit operation unit connected in sequence by material streams;

[0027] Moreover, for any stoichiometric reactor (RStoic) operation unit, they are all used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is preset to 1.5% - 3%;

[0028] For any heat exchanger (Heater) operation unit, their heat loads are all preset to -1.0×10 7 to -3.0×10 6 kJ / h;

[0029] The SSplit operation unit is used for splitting. Each SSplit operation unit includes 2 outlets. Denote the stream split from the upper outlet of the operation unit as the upper stream, and the stream split from the lower outlet of the operation unit as the lower stream. For any SSplit operation unit, their gas flow directions are preset as: 93% - 95% enters the upper stream, and their solid flow directions are preset as: 87% - 96% enters the lower stream. Among them, the upper stream of the SSplit operation unit in Class C1 is not connected to any operation unit, and the upper stream of the SSplit operation unit in Class C2 - C5 enters the mixer operation unit of the upper - stage suspension preheater; the lower stream of the SSplit operation unit in Class C1 - C3 enters the mixer operation unit of the lower - stage suspension preheater, the lower stream of the SSplit operation unit in Class C4 enters the Gibbs reactor operation unit in the decomposition furnace subsystem, and the lower stream of the SSplit operation unit in Class C5 enters the Gibbs reactor operation unit in the rotary kiln subsystem;

[0030] All feed streams in the suspension preheater subsystem are connected to the mixer operation unit in Class C1. The feed streams include the cement raw material stream and the raw material - carrying air stream at the same time. The outlet streams in the suspension preheater subsystem include the upper stream of the SSplit operation unit in Class C1 and the lower stream of the SSplit operation unit in Class C5 at the same time.

[0031] As a further preference of the present invention, in the step (S2), the decomposition furnace subsystem is used to simulate the processes of pulverized coal decomposition, combustion reaction, carbonate decomposition and surface heat dissipation, which are respectively realized by the yield reactor (RYield) operation unit, the Gibbs reactor (RGibbs) operation unit, the stoichiometric reactor operation unit and the heat stream connected to the stoichiometric reactor operation unit; among them, the yield reactor operation unit, the Gibbs reactor operation unit and the stoichiometric reactor operation unit are connected in sequence;

[0032] The yield reactor operation unit is controlled by the calculator module;

[0033] A stoichiometric reactor operation unit is used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is preset to 80%-82%;

[0034] The heat load in the hot stream is preset to -2.5×10 7 to -1.3×10 7 kJ / h;

[0035] In the decomposition furnace subsystem, the feed stream is connected to the yield reactor operation unit, and the feed stream is the material stream of the coal in the decomposition furnace; the outlet stream in the decomposition furnace subsystem is connected to the heat exchanger operation unit at the C5 level in the suspension preheater subsystem, and the outlet stream is the outlet material stream of the stoichiometric reactor operation unit.

[0036] As a further preference of the present invention, in the step (S2), the rotary kiln subsystem is used to simulate the processes of pulverized coal decomposition, combustion reaction, carbonate decomposition, surface heat dissipation, gas-solid separation and bypass air release, including a yield reactor operation unit, a mixer operation unit, a Gibbs reactor operation unit, a stoichiometric reactor operation unit, a heat exchanger operation unit, an SSplit operation unit and an FSplit operation unit connected in sequence; among them, the processes of simulating pulverized coal decomposition, combustion reaction, carbonate decomposition and surface heat dissipation are respectively realized by using the yield reactor operation unit, the Gibbs reactor operation unit, the stoichiometric reactor operation unit and the heat exchanger operation unit; the processes of simulating gas-solid separation and bypass air release are respectively realized by using the SSplit operation unit and the FSplit operation unit;

[0037] Among them, the yield reactor operation unit is controlled by the calculator module;

[0038] A stoichiometric reactor operation unit is used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is preset to 100%;

[0039] The heat load of the heat exchanger operation unit is preset to -7.0×10 7 to -5.0×10 7 kJ / h;

[0040] The gas-solid separation efficiency in the SSplit operation unit is preset to 100%;

[0041] In the FSplit operation unit, one stream is separated to simulate the air loss of the bypass air release system, which is recorded as the bypass air release stream, and the separation ratio of this bypass air release stream is preset to 3%-5%;

[0042] There are a total of 4 feed streams in the rotary kiln subsystem, specifically including rotary kiln coal, clean air entering the kiln, primary air, and secondary air. Among them, the rotary kiln coal stream is connected to the yield reactor operation module; the three streams of clean air entering the kiln, primary air, and secondary air are merged into a single stream by the mixer operation unit, and this single stream is then connected to the Gibbs reactor operation module. There are a total of 3 outlet streams, namely: the lower material stream in the SSplit operation unit serves as the cement clinker outlet stream and is not connected to any operation unit; the bypass bleed stream in the FSplit operation unit is not connected to any operation unit; the other streams in the FSplit operation unit except the bypass bleed stream are connected to the mixer operation unit in the organic solid waste decomposition subsystem.

[0043] As a further preference of the present invention, in the step (S2), the organic solid waste decomposition subsystem includes a mixer operation unit, a stoichiometric reactor operation unit, a Sep operation unit, a yield reactor operation unit, a mixer operation unit, and an FSplit operation unit connected in sequence; this organic solid waste decomposition subsystem is used to simulate the drying and decomposition process of organic solid waste, which are respectively realized by the stoichiometric reactor operation unit and the yield reactor operation unit; among them,

[0044] The stoichiometric reactor operation unit and the yield reactor operation unit are controlled by the calculator module;

[0045] After the organic solid waste stream passes through the stoichiometric reactor operation unit, the Sep operation unit is used for splitting to ensure that each type of organic solid waste is decomposed separately in the yield reactor operation unit. The decomposition products and the heat required for decomposition are respectively merged into a material stream and a heat stream by the mixer unit, and the two streams are respectively split by the FSplit operation unit. The splitting ratio is preset to 95:5. 95% is preset to enter the decomposition furnace subsystem, and the remaining 5% enters the rotary kiln subsystem;

[0046] Moreover, in this organic solid waste decomposition subsystem, the number of yield reactor operation units is 5 - 15, and the number of FSplit operation units is 2;

[0047] There are a total of 4 feed streams in the organic solid waste decomposition subsystem, specifically including organic solid waste, primary air, tertiary air in column A, and tertiary air in column B. Among them, the organic solid waste stream is connected to the stoichiometric reactor operation unit; the primary air, tertiary air in column A, and tertiary air in column B are mixed through the mixer operation unit and then connected to the yield reactor operation unit. There are a total of 4 outlet streams, specifically including 2 logistics streams split from 2 FSplit operation units and 2 heat streams. Among them, 1 logistics stream with a split ratio of 95% and 1 heat stream with a split ratio of 95% enter the Gibbs reactor operation unit in the decomposition furnace subsystem, and 1 logistics stream with a split ratio of 5% and 1 heat stream with a split ratio of 5% enter the Gibbs reactor operation unit in the rotary kiln subsystem.

[0048] As a further preference of the present invention, in the step (S1), the physical property method is specifically the PR - BM method.

[0049] The chemical components are pre - divided into three categories, namely: conventional components, solid - phase components, and unconventional components. Among them, the conventional components and solid - phase components are obtained by selection in the software database, and the unconventional components are obtained by new construction.

[0050] The conventional components include H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, and CO2.

[0051] The solid - phase components include C, CaCO3, CaO, MgCO3, MgO, and CaSO4.

[0052] The unconventional components include various organic solid wastes, coal, and the incombustible ash in both of them. At the same time, it also includes inert components, which are used to represent the components other than carbonates in cement raw meal, including SiO2, Al2O3, Fe2O3, K2O, Na2O, and SO3.

[0053] As a further preference of the present invention, in the step (S5 - 1), the interactive interface is implemented by software written in Excel software, MATLAB software, Python language, or software capable of implementing ActiveX technology connection.

[0054] Preferably, the interactive interface includes at least two interfaces. One interface is used to input the value or change range of feed parameters, and the other interface is used to input the properties of coal and organic solid waste. The properties of coal and organic solid waste include industrial analysis data, elemental analysis data, and dry - basis lower calorific value at the same time. Among them, the industrial analysis data includes the moisture content on the applied basis, ash content on the dry basis, volatile matter content on the dry basis, and fixed carbon content on the dry basis at the same time. The elemental analysis data includes C content, H content, O content, N content, S content, and Cl content at the same time.

[0055] More preferably, when the feed parameters in the step (S5-2) are fixed values, they are input into the corresponding stream of the steady-state process simulation model through the interaction interface; when the feed parameters in the step (S5-2) are within an interval range, they are input into the sensitivity analysis module of the steady-state process simulation model through the interaction interface.

[0056] As a further preference of the present invention, in the step (S5), based on the calculation results, it is determined whether to adjust the improved process. Specifically, it is determined whether to adjust the improved process based on the calculation results of the temperature of the cement kiln equipment, the calculation results of the flue gas emission volume, the calculation results of the flue gas component concentration, the calculation results of the coal consumption, or the calculation results of the organic solid waste co-incineration ratio.

[0057] As a further preference of the present invention, in the step (S4), the absolute value of the pre-selected acceptance limit value is pre-selected to be 4%-6%.

[0058] Through the above technical solutions conceived by the present invention, compared with the prior art, the following beneficial effects can be achieved:

[0059] (1) In the simulation and optimization method of the present invention, a steady-state process simulation model is established using Aspen Plus software, and by setting 4 subsystems including a suspension preheater subsystem, a decomposition furnace subsystem, a rotary kiln subsystem, and an organic solid waste decomposition subsystem in the simulation model, and cooperating with material streams and heat streams, it is possible to perform simulation calculation and analysis on aspects such as the temperature change, flue gas emission, mass balance, and energy balance of the core process units during the co-disposal of organic solid waste in the cement kiln system.

[0060] (2) The establishment of the steady-state process simulation model and the parameter selection of the operation units in the present invention are applicable to the process of co-disposing organic solid waste in cement kilns adopted by the vast majority of domestic cement enterprises. In particular, the present invention can separately set subsystems related to organic solid waste decomposition and bypass air release, and preferably abandon the assumption of adiabatic conditions in heat calculation, considering the heat loss caused by equipment heat dissipation, and has a high credibility.

[0061] (3) The present invention preferably selects specific operation units. For example, a stoichiometric reactor unit is used to simulate the decomposition process of cement raw meal, and a Gibbs reactor unit is used to simulate the combustion reaction process. Under the condition of ensuring simulation accuracy, the model calculation amount is reduced, and at the same time, the setting order of the operation units is reasonably adjusted, and the decomposition process of cement raw meal is set before the combustion reaction, so that the temperature calculation in the Gibbs reactor unit corresponding to the combustion reaction is closer to the actual production.

[0062] (4) Preferably, the present invention calculates the drying and decomposition processes of each type of organic solid waste separately. Adding or changing the types, quality, ratio, properties, etc. of organic solid waste does not require manual calculation of mixture parameters, and the model can automatically calculate and input the relevant parameters of the mixture.

[0063] (5) The model of the present invention is established for the co - disposal process of organic solid waste in a cement kiln. It can predict, in a quantitative way, the effects of changes in the types, feed rates, physical and chemical properties, etc. of single or multiple organic solid wastes on the cement kiln furnace temperature, flue gas emissions, coal consumption, or other production indicators during the co - disposal process of organic solid waste in a cement kiln, providing auxiliary data for cement enterprises to optimize the co - disposal process.

[0064] (6) In addition, the present invention can preferably set an interactive interface to operate and call the model. Except for debugging personnel, operators do not need to understand the modeling method or operation principle of Aspen Plus, reducing the learning cost and improving the universality of the present invention.

[0065] (7) The present invention conducts a full - process simulation of the cement firing system, breaking through the limitation of only simulating local processes of the cement firing system in mainstream cement process simulation research; in addition, the present invention uses chemical simulation software to model and simulate the co - disposal process of organic solid waste in a cement kiln, breaking through the problems of large computational amount and long time consumption in applying computational fluid dynamics in mainstream cement process simulation research; the purpose of the present invention focuses on predicting the impact of changes in production raw materials on production processes and production parameters after the cement plant is built and put into operation, which is also different from the mainstream cement process simulation research that focuses on the size and scale design of cement production equipment. Description of the Drawings

[0066] Figure 1 It is a gas - solid flow diagram for the co - disposal process of organic solid waste in a cement kiln.

[0067] Figure 2 It is a steady - state process simulation model for the co - disposal of organic solid waste in a cement kiln established using Aspen Plus software in the present invention.

[0068] Figure 3 is Figure 2 the legend of the operation units used in the steady - state process simulation model shown.

[0069] Figure 4 It is the model output result diagram in Example 1 of the present invention.

[0070] Figure 5 It is the output result diagram of the influence of sludge moisture content on the pollutant concentration in flue gas in Example 2 of the present invention (the corresponding sludge feed rate is fixed at 20 t / h, see Example 2 below for details); among them, Figure 5 (a) in Figure 5 corresponds to the SO2 concentration, andFigure 5 In (c) corresponds to the NO concentration, Figure 5 In (d) corresponds to the CO2 concentration.

[0071] Figure 6 It is the output result diagram of the influence of sludge feed rate and moisture content on temperature in Example 3 of the present invention; wherein, Figure 6 In (a) corresponds to the outlet flue gas temperature, Figure 6 In (b) corresponds to the decomposition furnace temperature.

[0072] Figure 7 It is the process schematic diagram corresponding to the embodiment of the present invention. Specific implementation manners

[0073] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0074] The simulation and optimization method of the cement kiln co-disposal of organic solid waste process in the present invention may include the following steps: (1) Open the Aspen Plus software, select the physical property method in the physical property library, and select or establish chemical components; (2) Select and add operation units and stream composition subsystems from the software model library, add modules to the subsystems and connect them to form a steady-state process simulation model; (3) Input the cement kiln feed parameters in the production process into the steady-state process simulation model for calculation to obtain calculation data such as temperature, flow rate and components in each subsystem; (4) Compare the calculation data with the production data of the corresponding production link. If the relative error exceeds the acceptance limit value, modify the operation unit parameters in the steady-state process simulation model, and repeat steps (3)-(4) until the relative error is within the acceptance limit value (relative error = (|simulation value - measured value|) ÷ measured value); (5) Establish an interactive interface and establish a link between the model feed parameters and the interactive interface; (6) Determine the expected improved process, and input the cement kiln feed parameters in the improved process into the steady-state process simulation model; (7) Run the simulation, obtain calculation data such as temperature, flow rate and components in each subsystem through the calculation of the steady-state process simulation model, analyze the calculation data and adjust the expected improved process to complete the process optimization process.

[0075] Specifically, it may include the following steps:

[0076] (1) Open the Aspen Plus software. In the physical property menu, select the physical property method used for software calculation, and select or establish the chemical components involved in software calculation;

[0077] (2) In the simulation menu, select and add operation units and streams from the software's model library, connect the operation units and streams to form different subsystems, and connect the subsystems to each other through the streams to form a combined system. Add "calculator", "design specification", and "sensitivity analysis" modules to the combined system to finally form a steady-state process simulation model;

[0078] (3) Input the feed parameters such as the mass flow rate, temperature, and chemical composition of the raw materials, fuels, and air fed into the cement kiln during the production process into the corresponding streams of the subsystems described in step (2) and run the simulation. After calculation by the steady-state process simulation model described in step (2), obtain the calculated data such as temperature, flow rate, and composition in each subsystem;

[0079] (4) Compare the calculated data obtained in step (3) with the production data of the corresponding production links. If the relative error exceeds the acceptance limit value, modify the parameters of the operation units described in step (2), and repeat steps (3) and (4) until the relative error is within the acceptance limit value;

[0080] (5) Establish an interactive interface in software written in Office software, MATLAB software, Python language, or software capable of implementing ActiveX technology connection, and establish a link between the streams and the sensitivity analysis module described in step (2) and the interactive interface;

[0081] (6) Determine the expected improved process, and input the feed parameters such as the mass flow rate, temperature, and chemical composition of the raw materials, fuels, and air to be fed into the cement kiln in the improved process into the corresponding streams or the sensitivity analysis module of the subsystems described in step (2) using the interactive interface described in step (5);

[0082] (7) Run the simulation. After calculation by the steady-state process simulation model described in step (2), obtain the calculated data such as temperature, flow rate, and composition in each subsystem, analyze the calculated data, and adjust the expected improved process to complete the process optimization process.

[0083] Among them, the physical property method described in step (1) can select the PR-BM method.

[0084] Among them, the chemical components described in step 1 may include: conventional components, solid phase components, and unconventional components. Conventional components and solid phase components are selected from the database provided by the software, and unconventional components need to be newly created by the user. The selected conventional components are H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, CO2; the selected solid phase components are C, CaCO3, CaO, MgCO3, MgO, CaSO4; the present invention divides the cement raw material components into CaCO3, MgCO3 and inert components, and the inert components replace SiO2, Al2O3, Fe2O3, K2O, Na2O, SO3 and other components except carbonates. The newly created unconventional components are: various types of organic solid waste, coal and the non-combustible ash in both, and the inert components in cement raw materials.

[0085] Among them, the subsystem described in step 2 may include four subsystems: suspension preheater, decomposition furnace, rotary kiln, and organic solid waste decomposition, which may respectively correspond to the three equipments of suspension preheater, decomposition furnace, and rotary kiln in cement production and the decomposition process of organic solid waste in the decomposition furnace or rotary kiln.

[0086] The suspension preheater subsystem can be divided into five levels from top to bottom. The four processes of gas-solid mixed heat exchange, carbonate decomposition, surface heat dissipation, and gas-solid separation in the preheater can be realized by the mixer, stoichiometric reactor (RStoic), heat exchanger, and SSplit units respectively. Each level of preheater can contain some or all of the four operating units. The decomposition reaction of calcium carbonate and magnesium carbonate is defined in the stoichiometric reactor unit, and the decomposition rate can be set to 1.5%-3%. The heat load in the heat exchanger can be set to -1.0×10 7 to -3.0×10 6 kJ / h. In the SSplit unit, the gas flow direction can be: 93%-95% enters the previous stage preheater; the solid flow direction can be: 87%-96% enters the next stage preheater.

[0087] The decomposition furnace system simulates the coal powder decomposition, combustion reaction, carbonate decomposition and surface heat dissipation process, which can be realized by the yield reactor unit (RYield), Gibbs reactor (RGibbs), stoichiometric reactor unit and the hot flow stream connected to the stoichiometric reactor unit. Among them, the yield reactor unit is controlled by the calculator module described in step 2. The decomposition reaction of two carbonates, calcium carbonate and magnesium carbonate, is defined in the stoichiometric reactor unit. The decomposition rate can be set to 80%-82%. The heat load in the hot flow stream can be -2.5×10 7 to -1.3×10 7 kJ / h.

[0088] The rotary kiln subsystem simulates the coal powder decomposition, combustion reaction, carbonate decomposition, surface heat dissipation, gas-solid separation and bypass ventilation processes. The first four processes can be implemented using the yield reactor unit, Gibbs reactor, stoichiometric reactor and heat exchanger unit respectively. The gas-solid separation and bypass ventilation processes can be implemented by SSplit and FSplit units respectively. Among them, the yield reactor unit is controlled by the calculator module described in step 2. The decomposition reaction of two carbonates, calcium carbonate and magnesium carbonate, is defined in the stoichiometric reactor unit. The decomposition rate of carbonate can be set to 100%. The heat load in the heat exchanger unit can be set to -7.0×10 7 to -5.0×10 7 kJ / h, the gas-solid separation efficiency in the SSplit unit can be set to 100%, and a stream is separated in the FSplit unit to simulate the wind loss in the bypass venting system, and the stream separation ratio can be set to 3%-5%.

[0089] The organic solid waste decomposition subsystem simulates the drying and decomposition process of organic solid waste, which is realized by the stoichiometric reactor and the yield reactor respectively. The stoichiometric reactor and the yield reactor unit are controlled by the calculator module described in step 2. After the organic solid waste stream is dried, the Sep module is used for diversion to ensure that each type of organic solid waste is decomposed separately in the yield reactor unit. After all the decomposition products of the organic solid waste components and the heat required for decomposition are combined by the mixer unit, the FSplit unit is used for diversion. 95% can be pre-set to enter the Gibbs reactor operation unit in the decomposition furnace system, and the remaining 5% can enter the Gibbs reactor operation unit in the rotary kiln subsystem. The number of yield reactor operation units in this subsystem can be 5-15.

[0090] The flow streams in each subsystem described in step 2 can be arranged according to different principles: the suspension preheater subsystem is arranged according to the gas and solid flow direction in the cement production process, such as Figure 1 As shown; the decomposition furnace system and the rotary kiln subsystem modify some process sequences based on the actual production process. The stream first passes through the corresponding operation unit of raw material decomposition, and then passes through the corresponding operation unit of combustion reaction; the organic solid waste decomposition subsystem is set according to the physical and chemical reaction process of drying and pyrolysis.

[0091] The calculator module in step 2 is used to control the operation unit in step 2, the design specification module in step 2 is used to control a variable in the steady-state process simulation model in step 2 to a specified value or a specified range, and the sensitivity analysis module in step 2 can be combined with the design specification module to adjust the feed parameters in step 3 to change within a specified range with a specified step length. The "transfer" module provided by the Aspen Plus software can be used in the steady-state process simulation model in step 2 for auxiliary calculation, but it is not necessary.

[0092] Among them, after the steady-state process simulation models described in Step 2 are combined as Figure 2 shown.

[0093] Among them, the acceptance limit value described in Step 4 can be 4% - 6%.

[0094] Among them, in Step 5, the interactive interface can be set to include at least two interfaces. One interface is used to input the feed temperature, flow rate value or range of variation, and the other interface is used to input the properties of coal and organic solid waste raw materials, such as industrial analysis data, elemental analysis data, dry basis lower calorific value, etc.

[0095] Among them, if the feed parameters described in Step 6 are fixed values, they are input into the corresponding stream of the steady-state process simulation model described in Step 2 through the interactive interface described in Step 5; if the feed parameters described in Step 6 are range values, they are input into the sensitivity analysis module of the steady-state process simulation model described in Step 2 through the interactive interface described in Step 5.

[0096] Among them, the calculated data described in Step 7 can be the temperature of the cement kiln equipment, the volume of flue gas emissions, the concentration of flue gas components, the coal consumption, or other production indicators.

[0097] The following are specific embodiments:

[0098] Embodiment 1:

[0099] The purpose of this embodiment is to explore the influence of the variation of the feed rate of refuse-derived fuel (RDF) with known properties in the range of 80 - 100 t / h on the coal consumption and the flow rate of the tertiary air in the decomposition furnace under the condition that the temperature of the decomposition furnace is maintained at 890°C. This purpose is achieved through the following technical solutions:

[0100] A simulation and optimization method for the co-disposal of organic solid waste in a cement kiln based on Aspen Plus, including the following steps:

[0101] (1) Open the Aspen Plus software. In the physical property menu, select the PR-BM method as the physical property method used for software calculations. The software database comes with conventional components and solid-phase components. In addition, for other components not included in the conventional component library and the solid-phase component library, they can be newly created through the entry for unconventional components in the software, and the specific properties of the components can be input by oneself. Select and add conventional components and solid-phase components from the software database. The selected conventional components are H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, CO2; the selected solid-phase components are C, CaCO3, CaO, MgCO3, MgO, CaSO4; the unconventional components are newly created by the user. The newly created unconventional components are RDF, coal, and the incombustible ash in both of them, the inert components in the raw cement meal, and the inert components replace the components other than carbonates such as SiO2, Al2O3, Fe2O3, K2O, Na2O, SO3 in the raw cement meal.

[0102] (2) Select and add operation units and streams from the model library of the Aspen Plus software, and connect the operation units and streams to form 4 subsystems: suspension preheater, decomposition furnace, rotary kiln, and organic solid waste decomposition. The settings of the operation units in each subsystem are as follows:

[0103] In the suspension preheater subsystem, it is divided into five levels, C1 - C5, from top to bottom. The C1 level includes three processes: gas-solid mixing heat transfer, surface heat dissipation, and gas-solid separation. The C5 level includes two processes: surface heat dissipation and gas-solid separation. Each of the C2 - C4 levels includes four processes: gas-solid mixing heat transfer, carbonate decomposition, surface heat dissipation, and gas-solid separation.

[0104] The four processes of gas-solid mixing heat transfer, carbonate decomposition, surface heat dissipation, and gas-solid separation are realized by a mixer, a stoichiometric reactor, a heat exchanger, and an SSplit unit respectively. The decomposition reactions of CaCO3 and MgCO3 are defined in the stoichiometric reactor unit. The decomposition rates in the stoichiometric reactor units of the C2 - C4 levels are 1.5%, 2.0%, and 2.5% respectively. The heat loads in the heat exchangers of the C1 - C5 levels are -6841783, -4719676, -6206905, -7391566, -8451027 kJ / h respectively. In the SSplit units of the C1 - C5 levels, for the gas flow: 95% enters the upper level, and the rest enters the lower level; for the solid flow: 96%, 90%, 87%, 87%, 90% of the C1 - C5 levels enter the lower level respectively, and the rest enter the upper level.

[0105] The decomposition furnace subsystem simulates the processes of pulverized coal decomposition, pulverized coal combustion, carbonate decomposition, and surface heat dissipation. The calculator module written in Fortran controls the yield reactor unit to decompose coal into C, H2, N2, Cl2, S, O2, H2O, and inert ash ASH according to its elemental composition. The decomposition products of coal and the heat required for decomposition undergo combustion reactions after mixing with other streams in the Gibbs reactor unit. The carbonate decomposition is achieved by the stoichiometric reactor unit, where the decomposition reactions of CaCO3 and MgCO3 are defined, and the reaction rates are both 80%. The stoichiometric reactor is connected to a hot stream with a heat load of -17879312 kJ / h in the hot stream.

[0106] The rotary kiln subsystem simulates the processes of pulverized coal decomposition, pulverized coal combustion, carbonate decomposition, surface heat dissipation, gas-solid separation, and bypass air release. The calculator module written in Fortran controls the yield reactor unit to decompose coal into C, H2, N2, Cl2, S, O2, H2O, and inert ash ASH according to its elemental composition. The decomposition products of coal and the heat required for decomposition undergo combustion reactions after mixing with other streams in the Gibbs reactor unit. The carbonate decomposition is achieved by the stoichiometric reactor unit, where the decomposition reactions of CaCO3 and MgCO3 are defined, and the reaction rates are both 100%. The heat load of the heat exchanger unit is -60941283 kJ / h. The gas-solid separation and bypass air release processes are respectively achieved by the SSplit and FSplit units. The gas-solid separation efficiency in the SSplit unit is 100%, and in the FSplit unit, one stream is separated to simulate the air loss in the bypass air release system, with a stream separation ratio of 3%.

[0107] In the organic solid waste decomposition subsystem, this subsystem simulates the drying and decomposition processes of organic solid waste, which are respectively achieved by the stoichiometric reactor and the yield reactor. The stoichiometric reactor and the yield reactor unit are controlled by the calculator module written in Fortran. After the organic solid waste stream is dried, the Sep module is used for splitting to ensure that each type of organic solid waste is separately decomposed into C, H2, N2, Cl2, S, O2, H2O, and inert ash ASH in the yield reactor unit. 95% of the decomposition products and the heat required for decomposition enter the Gibbs reactor unit in the decomposition furnace subsystem, and 5% enter the Gibbs reactor unit in the rotary kiln subsystem.

[0108] The streams within each subsystem are set according to different principles: the suspension preheater subsystem is arranged according to the gas and solid flow directions in the cement production process; the decomposition furnace subsystem and the rotary kiln subsystem modify part of the process sequence on the basis of the actual production process. The stream first passes through the corresponding operation unit for raw meal decomposition and then through the corresponding operation unit for combustion reaction; the organic solid waste decomposition subsystem is set according to the physical and chemical reaction processes of drying and pyrolysis. Each subsystem is connected through streams, and the finally connected steady-state process simulation model is asFigure 2 as shown

[0109] One transfer module, two design specification modules, and one sensitivity analysis module are set in the steady-state process simulation model. In this embodiment, the precalciner uses dual columns of tertiary air for air supply, which are divided into Column A and Column B. The transfer module copies the volumetric flow rate of the tertiary air stream in Column A of the precalciner air supply to the tertiary air stream in Column B to ensure that the volumetric flow rates of the tertiary air in Columns A and B are the same. Design specification module 1 stipulates that the molar fraction of O2 in the flue gas stream at the outlet of the preheater is 0.025, with an allowable error of 0.001. The manipulated variable is the tertiary air in Column A of the precalciner, and the variation range is 10 -5 -10 6 Nm 3 / h; Design specification module 2 stipulates that the temperature of the outlet stream of the Gibbs reactor in the precalciner subsystem (simulating the precalciner temperature) is 890 °C, with an allowable error of 0.1 °C. The manipulated variable is the mass flow rate of the coal stream in the precalciner. The sensitivity analysis module sets the manipulated variable as the mass flow rate of RDF in the organic solid waste stream, and the output variables are the volumetric flow rate of the tertiary air stream in Column A of the precalciner subsystem under standard conditions and the mass flow rate of the precalciner coal.

[0110] (3) Input the feed parameters into the corresponding streams in the subsystem. The feed parameters include solid feed parameters and air supply parameters. The solid feed parameters include cement raw meal, pulverized coal, and RDF. The composition of the cement raw meal stream (RAW-MATE) is decomposed into CaCO3, MgCO3, and an inert non-volatile component (RAW-M), where RAW-M replaces the components other than carbonates such as SiO2, Al2O3, Fe2O3, K2O, Na2O, and SO3 in the raw meal. The feeding positions of the pulverized coal include two places, namely the pre-combustion chamber of the precalciner and the kiln head of the rotary kiln. RDF is classified into the organic solid waste stream and undergoes the processes of drying, decomposition, and combustion in sequence. The parameter settings of each solid stream are shown in Table 1, and the elemental analysis and industrial analysis results of the coal and RDF are shown in Table 2.

[0111] Table 1 Input Parameters of Solid Materials

[0112]

[0113] Table 2 Elemental Analysis and Industrial Analysis Results of Coal and RDF

[0114]

[0115] *Mar: Refers to the moisture content on an as-received basis here and hereinafter;

[0116] *Fd: Refers to the fixed carbon on a dry basis here and hereinafter;

[0117] *Vd: Refers to the volatile matter on a dry basis here and hereinafter;

[0118] *Ad: Here and in the following text, it refers to dry basis ash.

[0119] The air supply parameters include three categories: decomposition furnace air supply, rotary kiln air supply and material carrying air. The decomposition furnace air supply includes primary air and double-row tertiary air (AB double-row), the rotary kiln air supply includes primary air and secondary air, and the cement raw material will also carry air when entering the preheater. The parameter settings of each air stream are shown in Table 3.

[0120] Table 3 Air supply input parameters

[0121]

[0122] * Standard conditions: Here and in the following text, standard conditions refer to 1 atm pressure and 0°C conditions, referred to as standard conditions.

[0123] Run the simulation and use the steady-state process simulation model to calculate the temperature, flow rate, composition and other calculation data in each subsystem.

[0124] (4) The temperature data and flue gas emission data in the suspension preheater subsystem are compared with the actual measured data in the factory. The comparison results are shown in Table 4 and Table 5. The relative error between the simulated temperature and the factory measured data is within 5%, so it can be considered that this model is consistent with the actual production.

[0125] Table 4 Comparison of temperature simulation results and measurement results

[0126]

[0127]

[0128] Table 5 Comparison of outlet flue gas simulation results and measurement results

[0129]

[0130] (5) Open Microsoft Excel and create a user interface in the spreadsheet. The interface includes two worksheets: Sheet 1 is used to modify the stream parameters and Sheet 2 is used to modify the raw material properties. Use the simulation workbook plug-in provided by Aspen software to link the stream parameters and sensitivity analysis module parameters in the steady-state process simulation model to the Excel spreadsheet.

[0131] (6) In sheet 1 described in step 5, input the initial parameters of the stream (as shown in Table 6 below), and in sheet 2, input the raw material properties (as shown in Table 7 below). In the corresponding cells of the sensitivity analysis module of sheet 1, input the lower limit of the RDF feed rate as 80 t / h, the upper limit of the feed rate as 100 t / h, the change step size as 1 t / h, and the decomposition furnace maintenance temperature as 890°C, as shown in Table 6.

[0132] Table 6 Stream parameter table in the spreadsheet of Example 1

[0133]

[0134]

[0135] Table 7 Raw material parameter table in the spreadsheet of Example 1

[0136]

[0137] (7) Click the "Reset Simulation" button and then click the "Run Simulation" button. Obtain the output results in the "Results" tab of the Sensitivity module in Aspen Plus software, analyze and process the output results. From the analysis results, the influence of the change of the RDF feed rate in the range of 80 - 100 t / h on the tertiary air volume flow rate and coal consumption in the decomposition furnace can be quantitatively analyzed under the conditions of maintaining the decomposition furnace temperature at 890 °C and the O2 volume fraction in the outlet flue gas at 2.5%. If the analysis results are presented in the form of a dot-line graph, it will be as Figure 4 shown.

[0138] Example 2:

[0139] The purpose of this example is to explore the influence of the change of the sludge moisture content in the range of 10% - 90% on the flue gas pollutant concentration under the condition that the feed amounts of three solid materials, namely cement raw meal, pulverized coal, and RDF, in the cement kiln remain unchanged, and an additional 20 t / h of dewatered sludge is added for co-disposal. This purpose is achieved through the following technical solutions:

[0140] A simulation and optimization method for co-disposing organic solid waste in a cement kiln based on Aspen Plus, comprising the following steps:

[0141] (1) Open the Aspen Plus software. In the physical properties menu, select the PR-BM method as the physical properties method used for software calculations. The software database comes with conventional components and solid-phase components. In addition, for other components not included in the conventional component library and the solid-phase component library, they can be newly created through the entry for unconventional components in the software, and the specific properties of the components can be input by oneself. Select and add conventional components and solid-phase components from the software database. The selected conventional components are H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, CO2; the selected solid-phase components are C, CaCO3, CaO, MgCO3, MgO, CaSO4; the unconventional components are newly created by the user, and the newly created unconventional components are RDF, sludge, coal, and the incombustible ash among the three, the inert components in cement raw meal, and the inert components replace the components other than carbonates such as SiO2, Al2O3, Fe2O3, K2O, Na2O, SO3 in cement raw meal.

[0142] (2) Select and add operation units and streams from the model library of the Aspen Plus software, and connect the operation units and streams to form four subsystems: suspension preheater, decomposition furnace, rotary kiln, and organic solid waste decomposition. Each subsystem uses streams to connect to form a steady-state process simulation model.

[0143] The process of establishing the steady-state process simulation model is basically the same as the process described in step 2 of Example 1. The difference is that 1 design specification module and 1 sensitivity analysis module are set in the steady-state process simulation model. The design specification module 1 stipulates that the O2 mole fraction in the flue gas stream at the outlet of the preheater is 0.02, with an allowable error of 0.0005. The manipulated variable is the volume flow rate of the primary air stream in the decomposition furnace, and the variation range is 10 -5 -10 6 Nm 3 / h; The sensitivity analysis module sets the manipulated variable as the moisture content of the sludge in the organic solid waste stream, and the output variables are the mass flow rates of SO2, CO, NO, and CO2 and the volume flow rate of the flue gas stream at the standard condition at the outlet of the suspension preheater subsystem.

[0144] (3) Input the feed parameters into the corresponding streams in the subsystem. The feed parameters include solid feed parameters and air supply parameters. The solid feed parameters include cement raw material, coal powder, RDF and sludge. The reaction involved in cement raw material is only carbonate decomposition. Other components do not participate in any reaction but only participate in the physical heat exchange process. Therefore, the cement raw material stream (RAW-MATE) is decomposed into CaCO3, MgCO3 and inert non-carbon stream components (RAW-M), where RAW-M replaces SiO2, Al2O3, Fe2O3, K2O, Na2O, SO3 and other components in the raw material except carbonate. The feeding position of coal powder includes two places, namely the precombustion chamber of the decomposition furnace and the kiln head of the rotary kiln. RDF and sludge are classified as components into the organic solid waste stream and are dried, decomposed and burned in turn. The parameter settings of each solid stream are shown in Table 8, and the elemental analysis and industrial analysis results of coal, RDF and sludge are shown in Table 9.

[0145] Table 8 Solid material input parameters

[0146]

[0147] Table 9 Elemental analysis and industrial analysis results of coal and RDF

[0148]

[0149] The air supply parameter setting is the same as the air supply parameter setting described in step 3 of Example 1.

[0150] In the factory test measurement data, no sludge was added, so the mass flow rate of the sludge component was set to 0, and the simulation was run. The steady-state process simulation model was used to calculate the temperature, flow rate, and components in each subsystem.

[0151] (4) Compare the temperature data and flue gas emission data in the suspension preheater subsystem with the factory data, and verify that the result is the same as step 4 in Example 1.

[0152] (5) Open a spreadsheet and establish a user interface in the spreadsheet. The interface includes two worksheets: Sheet 1 is used to modify the stream parameters, and Sheet 2 is used to modify the raw material properties. Use the simulation workbook plug-in provided by Aspen software to link the stream parameters and sensitivity analysis module parameters in the steady-state process simulation model to the spreadsheet.

[0153] (6) In sheet 1 described in step 5, input the initial parameters of the stream (as shown in Table 10), and in sheet 2, input the raw material properties (as shown in Table 11). In the corresponding cells of the sensitivity analysis module in sheet 1, input the lower limit of the sludge moisture content as 10%, the upper limit as 90%, and the change step size as 5%, as shown in Table 10.

[0154] Table 10 Stream Parameter Table of Example 2

[0155]

[0156] Table 11 Raw Material Parameter Table of Example 2 (this table is also continued to be used in Example 3 below)

[0157]

[0158] (7) Click the "Reset Simulation" button and then click the "Run Simulation" button. Obtain the output results in the "Results" tab of the Sensitivity module in Aspen Plus software. Analyze and process the output results. It can be seen from the analysis results that under the condition that the feeding amounts of three solid materials, namely cement raw meal, pulverized coal, and RDF, remain unchanged in the cement kiln, when dehydrated sludge is additionally added for co-disposal, the influence of the change of sludge moisture content in the range of 10 - 90% on the concentration of flue gas pollutants under the condition that the sludge feeding amount is 20 t / h is as Figure 5 shown.

[0159] Example 3:

[0160] The purpose of this example is to explore the allowable ranges of sludge feeding amount and moisture content under the condition that the feeding amounts of three solid materials, namely cement raw meal, pulverized coal, and RDF, remain unchanged in the cement kiln, when dehydrated sludge is additionally added for co-disposal, and to keep the decomposition furnace temperature between 880 - 905 °C and the outlet flue gas temperature below 360 °C. This purpose is achieved through the following technical solutions:

[0161] A simulation and optimization method for co-disposing organic solid waste in a cement kiln based on Aspen Plus, comprising the following steps:

[0162] (1) Open the Aspen Plus software. In the physical properties menu, select the PR-BM method as the physical properties method used for software calculations. The software database comes with conventional components and solid-phase components. In addition, for other components not included in the conventional component library and the solid-phase component library, they can be newly created through the entry for unconventional components in the software, and the specific properties of the components can be input by oneself. Select and add conventional components and solid-phase components from the software database. The selected conventional components are H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, CO2; the selected solid-phase components are C, CaCO3, CaO, MgCO3, MgO, CaSO4; the unconventional components are newly created by the user, and the newly created unconventional components are RDF, sludge, coal, and the incombustible ash among the three, the inert components in the cement raw meal, and the inert components replace the components other than carbonates such as SiO2, Al2O3, Fe2O3, K2O, Na2O, SO3 in the cement raw meal.

[0163] (2) Select and add operating units and streams from the model library of the Aspen Plus software, and connect the operating units and streams to form four subsystems: suspension preheater, decomposition furnace, rotary kiln, and organic solid waste decomposition. Each subsystem uses streams to connect to form a steady-state process simulation model.

[0164] The process of establishing the steady-state process simulation model is basically the same as the process described in step 2 of Example 1. The difference is that one design specification module and one sensitivity analysis module are set in the steady-state process simulation model. The design specification module 1 stipulates that the O2 molar fraction in the flue gas stream at the outlet of the preheater is 0.02, with an allowable error of 0.0005. The manipulated variable is the volume flow rate of the primary air in the decomposition furnace, with a variation range of 10 -5 -10 6 Nm 3 / h; the sensitivity analysis module sets the manipulated variables as the sludge feed rate and moisture content in the organic solid waste stream, and the output variables are the temperature of the outlet stream of the Gibbs reactor in the decomposition furnace subsystem (simulating the decomposition furnace temperature) and the temperature of the outlet flue gas stream in the suspension preheater subsystem.

[0165] (3) Input the feed parameters into the corresponding streams in the subsystems. The feed parameter settings are the same as those described in step 3 of Example 2.

[0166] (4) Compare the temperature data and flue gas emission data in the suspension preheater subsystem with the plant data. The verification results are the same as those in step 4 of Example 2.

[0167] (5) Open the spreadsheet and create a user interface in the spreadsheet. The user interface consists of 2 worksheets (sheets). Sheet 1 is used to modify the stream parameters, and Sheet 2 is used to modify the raw material properties. Use the simulation workbook plugin built into Aspen software to link the stream parameters and the parameters of the sensitivity analysis module in the steady-state process simulation model to the Excel spreadsheet.

[0168] (6) Enter the initial stream parameters (as shown in Table 12) in Sheet 1 described in step 5, and enter the raw material properties (as shown in Table 11 above) in Sheet 2. In the corresponding cells of the sensitivity analysis module in Sheet 1, enter the lower limit value of the sludge moisture content as 10%, the upper limit value as 90%, and the change step as 5%; the lower limit value of the sludge feed rate as 1 t / h, the upper limit value as 20 t / h, and the change step as 2 t / h, as shown in Table 12.

[0169] Table 12 Stream parameter table in the spreadsheet in Example 3

[0170]

[0171]

[0172] (7) Click the "Reset Simulation" button and then click the "Run Simulation" button. Obtain the output results in the "Results" tab of the sensitivity module in Aspen Plus software, copy the results to the Excel output result table, and perform analysis and processing on the data. The analysis results are as Figure 6 shown. As can be seen from Figure 6 (a) in, the flue gas temperature at the outlet of the preheater is negatively correlated with the sludge moisture content. The higher the sludge moisture content, the lower the outlet flue gas temperature. As the sludge feed rate increases, the rate of change of the outlet flue gas temperature with the change of the sludge moisture content gradually increases. When the sludge feed rate is 5 t / h and the sludge moisture content increases from 10% to 90%, the outlet flue gas temperature decreases from 371.0 °C to 357.6 °C; when the sludge feed rate is 15 t / h and the sludge moisture content increases from 10% to 90%, the outlet flue gas temperature decreases from 391.5 °C to 351.9 °C. From Figure 6 (b) in, it can be seen that the decomposition furnace temperature is also negatively correlated with the sludge moisture content, and the change law of the decomposition furnace temperature is similar to that of the flue gas temperature at the outlet of the preheater. When the sludge feed rate is 5 t / h and the sludge moisture content increases from 10% to 90%, the outlet flue gas temperature decreases from 922.9 °C to 893.8 °C; when the sludge feed rate is 15 t / h and the sludge moisture content increases from 10% to 90%, the outlet flue gas temperature decreases from 949.3 °C to 864.5 °C. Compared with the influence of the change of the sludge moisture content on the flue gas temperature at the outlet of the preheater, the influence of the sludge moisture content on the decomposition furnace temperature is more intense.

[0173] When the feeding amounts of three solid materials, namely cement raw meal, pulverized coal and RDF, remain unchanged in a cement kiln, if it is desired to maintain the temperature in the decomposition furnace between 880 °C and 905 °C and the outlet flue gas temperature below 360 °C, when the sludge feeding amount is 7.2 t / h, the allowable range of sludge moisture content can reach the maximum: 55% - 90%; when the sludge feeding amount is 20 t / h, the sludge moisture content needs to be restricted within a very narrow range: 67% - 69%.

[0174] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A simulation and optimization method for the co - disposal of organic solid waste in a cement kiln, characterized in that, The steps include the following: (S1) Using Aspen Plus software, select the physical property method for software calculation, and at the same time select the conventional components and solid-phase components involved in the software calculation, and use the other pre-selected components as unconventional components to create the unconventional components involved in the software calculation; (S2) Establish a steady-state process simulation model, which includes several subsystems, and each subsystem includes streams and several operation units; the subsystems are interconnected through streams; these subsystems include: Suspension preheater subsystem: used to correspond to the suspension preheater equipment in cement production, and the streams therein are arranged according to the gas and solid flow directions in the cement production process; Calciner subsystem: used to correspond to the calciner equipment in cement production, including the operation unit corresponding to raw material decomposition and the operation unit corresponding to combustion reaction; the streams in this calciner subsystem are set to pass through the operation unit corresponding to raw material decomposition in the calciner subsystem first, and then pass through the operation unit corresponding to combustion reaction in the calciner subsystem; among them, the operation unit corresponding to combustion reaction is the Gibbs reactor operation unit; Rotary kiln subsystem: used to correspond to the rotary kiln equipment in cement production, including the operation unit corresponding to raw material decomposition and the operation unit corresponding to combustion reaction; the streams in this rotary kiln subsystem are set to pass through the operation unit corresponding to raw material decomposition in the rotary kiln subsystem first, and then pass through the operation unit corresponding to combustion reaction in the rotary kiln subsystem; among them, the operation unit corresponding to combustion reaction is the Gibbs reactor operation unit; Organic solid waste decomposition subsystem: used to correspond to the decomposition process of organic solid waste in the calciner equipment and rotary kiln equipment in cement production, and the streams therein are set according to the physical and chemical reaction processes of drying and pyrolysis in sequence; The steady-state process simulation model also includes: a calculator module, a design specification module, and a sensitivity analysis module, where: The calculator module: used to control the calculation process of each operation unit; The design specification module: used to control a certain variable in this steady-state process simulation model to make it a specified value or a specified range; The sensitivity analysis module: used to cooperate with the design specification module to make a certain variable change within a specified range at a preset step size; (S3) According to the feed parameters in the production process, input these feed parameters into the corresponding streams in the steady-state process simulation model obtained in step (S2) for simulation, and through the calculation of the model, obtain the calculation results of each subsystem; The feed parameters also include the feed stream types and feed stream parameters; among them, the feed stream types include: different raw materials, different fuels, and air fed into the cement kiln; the feed stream parameters include: mass flow rate, temperature, and chemical components; The calculation results also include: temperature, flow rate, and components; (S4) Compare the calculation results obtained in step (S3) with the measured values in the production process. If the relative error exceeds the pre-selected acceptance limit value, modify the operation unit parameters in the steady-state process simulation model in step (S2), and repeat steps (S3) and (S4) until the relative error does not exceed the pre-selected acceptance limit value; (S5) Based on a pre-selected improved process, input the feed parameters corresponding to the improved process into the steady-state process simulation model. Through the calculation of the model, obtain the calculation results of each subsystem; based on the calculation results, determine whether to adjust the improved process to achieve process optimization.

2. The method according to claim 1, wherein The step (S5) specifically includes the following sub-steps: (S5-1) Establish an interactive interface to link the streams and the sensitivity analysis module in the steady-state process simulation model to the interactive interface respectively; (S5-2) Based on a pre-selected improved process, input the feed parameters corresponding to the improved process into the steady-state process simulation model through the interactive interface for simulation. Through the calculation of the model, obtain the calculation results of each subsystem; Based on the calculation results, determine whether to adjust the improved process to achieve process optimization.

3. The method according to claim 1, wherein In the step (S2), the suspension preheater subsystem is divided into five levels C1 - C5 from top to bottom. The four processes of gas-solid mixed heat transfer, carbonate decomposition, surface heat dissipation, and gas-solid separation that occur in the suspension preheater equipment in cement production are respectively realized by the mixer operation unit, the stoichiometric reactor operation unit, the heat exchanger operation unit, and the SSplit operation unit; among them, the C1 level includes a mixer operation unit, a heat exchanger operation unit, and an SSplit operation unit connected in sequence by material streams; each of the C2 - C4 levels includes a mixer operation unit, a stoichiometric reactor operation unit, a heat exchanger operation unit, and an SSplit operation unit connected in sequence by material streams; the C5 level includes a heat exchanger operation unit and an SSplit operation unit connected in sequence by material streams; Moreover, for any stoichiometric reactor operation unit, they are all used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is pre-set to 1.5% - 3%; For any heat exchanger operation unit, their heat loads are all preset to -1.0×10 7 to -3.0×10 6 kJ / h; The SSplit operation unit is used for splitting. Each SSplit operation unit has 2 outlets. Denote the stream split from the upper outlet of the operation unit as the upper material stream, and denote the stream split from the lower outlet of the operation unit as the lower material stream; for any SSplit operation unit, their gas flow directions are pre-set as: 93% - 95% enter the upper material stream, and their solid flow directions are pre-set as: 87% - 96% enter the lower material stream; among them, the upper material stream of the SSplit operation unit in the C1 level is not connected to any operation unit, and the upper material stream of the SSplit operation unit in the C2 - C5 levels enters the mixer operation unit of the upper-level suspension preheater; the lower material stream of the SSplit operation unit in the C1 - C3 levels enters the mixer operation unit of the lower-level suspension preheater, the lower material stream of the SSplit operation unit in the C4 level enters the Gibbs reactor operation unit in the decomposition furnace subsystem, and the lower material stream of the SSplit operation unit in the C5 level enters the Gibbs reactor operation unit in the rotary kiln subsystem; All feed streams in the suspension preheater subsystem are connected to the mixer operation unit in the C1 stage. The feed streams include both the raw cement feed stream and the raw material-carrying air stream. The outlet streams in the suspension preheater subsystem include both the upper stream of the SSplit operation unit in the C1 stage and the lower stream of the SSplit operation unit in the C5 stage.

4. The method according to claim 1, wherein In the step (S2), the decomposition furnace subsystem is used to simulate the processes of pulverized coal decomposition, combustion reaction, carbonate decomposition, and surface heat dissipation, which are respectively realized by the yield reactor operation unit, the Gibbs reactor operation unit, the stoichiometric reactor operation unit, and the heat stream connected to the stoichiometric reactor operation unit. Among them, the yield reactor operation unit, the Gibbs reactor operation unit, and the stoichiometric reactor operation unit are connected in sequence. The yield reactor operation unit is controlled by the calculator module. The stoichiometric reactor operation unit is used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is preset to 80%-82%. The heat load in the hot stream is preset to -2.5×10 7 to -1.3×10 7 kJ / h; The feed stream in the decomposition furnace subsystem is connected to the yield reactor operation unit, and the feed stream is the material stream of the pulverized coal in the decomposition furnace. The outlet stream in the decomposition furnace subsystem is connected to the heat exchanger operation unit in the C5 stage of the suspension preheater subsystem, and the outlet stream is the outlet material stream of the stoichiometric reactor operation unit.

5. The method according to claim 1, wherein In the step (S2), the rotary kiln subsystem is used to simulate the processes of pulverized coal decomposition, combustion reaction, carbonate decomposition, surface heat dissipation, gas-solid separation, and bypass air release, including the yield reactor operation unit, the mixer operation unit, the Gibbs reactor operation unit, the stoichiometric reactor operation unit, the heat exchanger operation unit, the SSplit operation unit, and the FSplit operation unit connected in sequence. Among them, the processes of pulverized coal decomposition, combustion reaction, carbonate decomposition, and surface heat dissipation are respectively realized by the yield reactor operation unit, the Gibbs reactor operation unit, the stoichiometric reactor operation unit, and the heat exchanger operation unit. The processes of gas-solid separation and bypass air release are respectively realized by the SSplit operation unit and the FSplit operation unit. Among them, the yield reactor operation unit is controlled by the calculator module. The stoichiometric reactor operation unit is used to define the decomposition reactions of calcium carbonate and magnesium carbonate, and the decomposition rate is preset to 100%. The heat load of the heat exchanger operation unit is preset to -7.0×10 7 to -5.0×10 7 kJ / h; The gas-solid separation efficiency in the SSplit operation unit is preset to 100%. In the FSplit operation unit, one stream is separated to simulate the air loss in the bypass air release system, denoted as the bypass air release stream, and the separation ratio of this bypass air release stream is preset to 3%-5%. There are a total of 4 feed streams in the rotary kiln subsystem, specifically including rotary kiln coal, clean air entering the kiln, primary air, and secondary air. Among them, the rotary kiln coal stream is connected to the productivity reactor operation module; the three streams of clean air entering the kiln, primary air, and secondary air are merged into a single stream by the mixer operation unit, and this single stream is then connected to the Gibbs reactor operation module. There are a total of 3 outlet streams, namely: the lower material stream in the SSplit operation unit serves as the cement clinker outlet stream and is not connected to any operation unit; the bypass bleed stream in the FSplit operation unit is not connected to any operation unit; the other streams in the FSplit operation unit except the bypass bleed stream are connected to the mixer operation unit in the organic solid waste decomposition subsystem.

6. The method according to claim 1, wherein In the step (S2), the organic solid waste decomposition subsystem includes a mixer operation unit, a stoichiometric reactor operation unit, a Sep operation unit, a productivity reactor operation unit, a mixer operation unit, and an FSplit operation unit connected in sequence; this organic solid waste decomposition subsystem is used to simulate the drying and decomposition processes of organic solid waste, which are respectively realized by the stoichiometric reactor operation unit and the productivity reactor operation unit. Among them, The stoichiometric reactor operation unit and the productivity reactor operation unit are controlled by the calculator module; After the organic solid waste stream passes through the stoichiometric reactor operation unit, the Sep operation unit is used for splitting to ensure that each type of organic solid waste is decomposed separately in the productivity reactor operation unit. The decomposition products and the heat required for decomposition are respectively merged into a material stream and a heat stream by the mixer unit. The two streams are respectively split by the FSplit operation unit, and the split ratio is preset to 95:

5. 95% is preset to enter the decomposition furnace subsystem, and the remaining 5% enters the rotary kiln subsystem. Moreover, in this organic solid waste decomposition subsystem, the number of productivity reactor operation units is 5 - 15, and the number of FSplit operation units is 2; There are a total of 4 feed streams in the organic solid waste decomposition subsystem, specifically including organic solid waste, primary air, tertiary air in column A, and tertiary air in column B. Among them, the organic solid waste stream is connected to the stoichiometric reactor operation unit; the primary air, tertiary air in column A, and tertiary air in column B are connected to the productivity reactor operation unit after being mixed by the mixer operation unit. There are a total of 4 outlet streams, specifically including 2 material streams and 2 heat streams split from the 2 FSplit operation units. Among them, 1 material stream with a split ratio of 95% and 1 heat stream with a split ratio of 95% enter the Gibbs reactor operation unit in the decomposition furnace subsystem, and 1 material stream with a split ratio of 5% and 1 heat stream with a split ratio of 5% enter the Gibbs reactor operation unit in the rotary kiln subsystem.

7. The method according to claim 1, wherein In the step (S1), the physical property method specifically selects the PR - BM method; The chemical components are pre - divided into three categories, namely: conventional components, solid - phase components, and unconventional components. Among them, the conventional components and solid - phase components are obtained by selecting in the software database, and the unconventional components are obtained by new construction; The conventional components include H2O, N2, O2, NO2, NO, S, SO2, SO3, H2, Cl2, HCl, CO, and CO2; The solid-phase components include C, CaCO3, CaO, MgCO3, MgO, and CaSO4; The unconventional components include various organic solid wastes, coal, and the incombustible ash in both, and also include inert components, which are used to represent the components other than carbonates in the cement raw meal, including SiO2, Al2O3, Fe2O3, K2O, Na2O, and SO3.

8. The method according to claim 2, wherein In the step (S5-1), the interactive interface is implemented by software written in Excel software, MATLAB software, Python language, or software capable of implementing ActiveX technology connection.

9. The method according to claim 8, wherein In the step (S5-1), the interactive interface includes at least two interfaces. One interface is used to input the value or range of variation of the feed parameters, and the other interface is used to input the properties of coal and organic solid wastes; the properties of coal and organic solid wastes include industrial analysis data, elemental analysis data, and dry basis lower calorific value at the same time: among them, the industrial analysis data includes the moisture content on the applied basis, the ash content on the dry basis, the volatile matter content on the dry basis, and the fixed carbon content on the dry basis; the elemental analysis data includes the C content, H content, O content, N content, S content, and Cl content.

10. The method according to claim 8, wherein When the feed parameter in the step (S5-2) is a fixed value, it is input into the corresponding stream of the steady-state process simulation model through the interactive interface; when the feed parameter in the step (S5-2) is a range, it is input into the sensitivity analysis module of the steady-state process simulation model through the interactive interface.

11. The method according to claim 1, wherein In the step (S5), based on the calculation results, it is judged whether to adjust the improved process, specifically based on the calculation results of the cement kiln equipment temperature, the flue gas emission volume, the flue gas component concentration, the coal consumption, or the organic solid waste co-incineration ratio, to judge whether to adjust the improved process.

12. The method according to claim 1, wherein In the step (S4), the absolute value of the pre-selected acceptance limit value is pre-selected as 4%-6%.

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