Boiler operation support device and operation support method

Abstract

The present invention provides a boiler operation support device and operation support method that can output combustion conditions that mitigate the corrosive environment of the boiler. [Solution] The system includes a processing circuit 11, which performs a chemical thermodynamic analysis for each of a plurality of combustion conditions using the elemental composition of the fuel, the air ratio included in the combustion conditions, the combustion reaction temperature, and a predetermined assumed temperature of the heat transfer tube surface to estimate the composition of the combustion gas phase and its generation amount on the heat transfer tube surface, as well as the composition of the corrosive condensed phase substance. Based on the composition of the combustion gas phase and its generation amount, it calculates the concentration of the corrosive gas. It generates point cloud data consisting of a collection of data including the composition of the corrosive condensed phase substance and the concentration of the corrosive gas corresponding to each combustion condition. From the point cloud data, it searches for data in which the composition of the corrosive condensed phase substance satisfies the conditions for suppressing corrosion on the heat transfer tube surface and the concentration of the corrosive gas is below a predetermined concentration, and performs an optimization calculation to output the combustion condition corresponding to that data.

Description

[Technical Field]

[0001] This disclosure relates to a boiler operation support device and an operation support method. [Background technology]

[0002] In the operation of boilers using fuels that are expected to cause corrosion of heat transfer tubes such as superheaters, it is important to optimize the combustion reaction temperature and air ratio according to the fuel used in order to mitigate the corrosive environment. In particular, when using waste materials such as biomass and waste plastics as boiler fuel, mitigating the corrosive environment is important for extending the lifespan of the boiler.

[0003] Traditionally, when operating a boiler, the operator monitors the boiler's operating conditions and adjusts the combustion reaction temperature and air-fuel ratio. Therefore, such adjustments depend on the operator's skills and experience, leading to variations in the adjustments.

[0004] Patent Document 1 describes a method for predicting sulfur corrosion of boiler furnace wall tubes, which involves calculating the pseudo-equilibrium oxygen partial pressure and pseudo-equilibrium sulfur partial pressure using the equilibrium constant at the temperature of the furnace wall tubes of a boiler fueled by pulverized coal, and then using these to predict the distribution of the degree of sulfur corrosion of the furnace wall tubes. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-44038 [Overview of the project] [Problems that the invention aims to solve]

[0006] While the technology disclosed in Patent Document 1 can predict the distribution of sulfidation corrosion in boiler furnace wall tubes, it cannot determine combustion conditions that can mitigate the corrosive environment of the boiler. Combustion conditions include combustion reaction temperature and air ratio.

[0007] This disclosure was made to solve the above-mentioned problems and aims to provide a boiler operation support device and operation support method that can output combustion conditions that mitigate the corrosive environment of the boiler. [Means for solving the problem]

[0008] To achieve the above objective, a boiler operation support device according to one embodiment of the present disclosure is a boiler operation support device in which heat transfer tubes are installed in a passage through which combustion gas produced by the combustion of fuel passes, and comprises a processing circuit, the processing circuit estimates the composition and amount of the combustion gas phase on the surface of the heat transfer tube by performing a chemical thermodynamic analysis on each of a plurality of combustion conditions, including the air ratio and combustion reaction temperature, using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature on the surface of the heat transfer tube, as well as the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube, or the composition and The system estimates the amount of deposition, calculates the concentration of corrosive gas on the heat transfer tube surface based on the composition of the combustion gas phase on the heat transfer tube surface and its generation amount, generates point cloud data consisting of a collection of data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its deposition amount, and the concentration of the corrosive gas, corresponding to each combustion condition, searches for data from the point cloud data where the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its deposition amount, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of the corrosive gas is below a predetermined concentration, and outputs the combustion condition corresponding to that data, thereby performing an optimization calculation.

[0009] Furthermore, a boiler operation support method according to one aspect of the present disclosure is a boiler operation support method in which heat transfer tubes are installed in a passage through which combustion gas produced by the combustion of fuel passes, and for each of a plurality of combustion conditions including air ratio and combustion reaction temperature as combustion conditions, a chemical thermodynamic analysis is performed using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions and a predetermined assumed temperature of the heat transfer tube surface to estimate the composition of the combustion gas phase on the heat transfer tube surface and the amount thereof generated, as well as the composition of corrosive condensed phase material deposited on the heat transfer tube surface, or the composition of the corrosive condensed phase material and the amount thereof deposited, and the An optimization calculation is performed to calculate the concentration of corrosive gas on the heat transfer tube surface based on the composition of the combustion gas phase on the heat transfer tube surface and the amount generated thereof, generate point cloud data consisting of a collection of data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of precipitation thereof, and the concentration of the corrosive gas, corresponding to each of the combustion conditions, search for data from the point cloud data in which the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of precipitation thereof, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of the corrosive gas is below a predetermined concentration, and output the combustion conditions corresponding to such data. [Effects of the Invention]

[0010] This disclosure provides a boiler operation support device and operation support method having the configuration described above, which can output combustion conditions that mitigate the corrosive environment of the boiler. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an example of a boiler targeted by the boiler operation support system of this embodiment. [Figure 2] Figure 2 is a block diagram showing the schematic configuration of the boiler operation support device of this embodiment. [Figure 3] Figure 3 shows an example of the chemical thermodynamic analysis flow performed by the processing circuit. [Figure 4]FIG. 4 is a state diagram plotting a part of analysis data for an example of the composition of a corrosive condensed-phase substance deposited on the surface of a heat transfer tube in chemical thermodynamics analysis. [Figure 5] FIG. 5 is a state diagram plotting a part of analysis data for an example of the composition of a corrosive condensed-phase substance deposited on the surface of a heat transfer tube in chemical thermodynamics analysis. [Figure 6] FIG. 6 is a diagram plotting analysis data on a graph with the horizontal axis being the smelting recovery rate and the vertical axis being the concentration of NOx, which is a corrosive gas. [Figure 7] FIG. 7 is a diagram showing the combustion conditions corresponding to the analysis data.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. In the following, the same or corresponding elements throughout all the drawings are denoted by the same reference numerals, and the overlapping description thereof is omitted. Also, the present disclosure is not limited to the following embodiments.

[0013] (Embodiment) FIG. 1 is a schematic diagram showing an example of a boiler that is the target of the boiler operation support device of the present embodiment.

[0014] The boiler 1 shown in FIG. 1 is a two-stage combustion boiler, and includes a main body 2 having a combustion chamber 2a with a primary combustion region R1 and a secondary combustion region R2 formed therein and a gas flow path, a plurality of burners 3, a plurality of secondary air supply ports 4, and heat transfer tubes 5 constituting a superheater. The burners 3 and the secondary air supply ports 4 are connected to the combustion chamber 2a, and the heat transfer tubes 5 are arranged in a flue, which is a passage through which combustion gas above the combustion chamber 2a passes. The burners 3 burn the fuel blown in together with the primary air. Note that the primary combustion region R1 and the secondary combustion region R2 are not necessarily limited to the regions shown in the figure.

[0015] In this boiler 1, in the combustion chamber 2a, a primary combustion reaction occurs where the fuel injected from the burner 3 and the primary air are mixed and most of the fuel is burned in the primary combustion region R1. Further, a secondary combustion reaction occurs where the unburned fuel is burned in the secondary combustion region R2 by the secondary air blown out from the secondary air supply port 4. The high-temperature combustion gas generated in this way is led from the combustion chamber 2a to the flue and heat-exchanged in the heat transfer tube 5. Then, the combustion gas generated in the boiler 1 is finally discharged from the chimney. Also, the combustion ash generated by the primary combustion reaction and the secondary combustion reaction is discharged from the discharge port 6 at the lower end of the main body 2. Hereinafter, the heat transfer tube 5 is also referred to as the flue heat transfer tube 5.

[0016] Also, the boiler 1 includes an operating device 7. An operator can operate the operating device 7 to adjust the operation of the boiler 1 such as the combustion conditions. The combustion conditions include the combustion reaction temperature and the air ratio. In a two-stage combustion type boiler like the boiler 1 of this example, the combustion conditions include the primary combustion reaction temperature, the primary air ratio for setting the primary air amount, the secondary combustion reaction temperature, and the secondary air ratio for setting the secondary air amount.

[0017] FIG. 2 is a block diagram showing the schematic configuration of the boiler operation support device of this embodiment. The boiler operation support device 10 shown in FIG. 2 includes a processing circuit 11 that performs various signal processes. The processing circuit 11 has a computer such as a microcontroller, a personal computer, a PLC (Programmable Logic Controller), etc. More specifically, the processing circuit 11 includes a processor 12, a memory 13, and a peripheral circuit 14.

[0018] The processor 12 includes, for example, a CPU or MPU. The memory 13 includes volatile memory such as ROM, RAM, and registers, and non-volatile memory such as flash memory. The memory 13 pre-stores a program that the processor 12 will execute. The peripheral circuit 14 includes an input / output interface, etc. The processor 12, memory 13, and peripheral circuit 14 communicate data with each other via the bus 15. The processor 12 executes the program stored in memory 13, causing the processing circuit 11 to perform predetermined processing.

[0019] Furthermore, the boiler operation support device 10 includes a data acquisition device 16 and an output device 17. The data acquisition device 16 may be configured, for example, as an input device for user input operations, or as a communication interface for receiving data from other devices. Data input from the data acquisition device 16 is transmitted to a memory 13 or the like via peripheral circuits 14. The output device 17 may be configured as a display device that acquires calculation results from the processor 12 via peripheral circuits 14 and displays them on a screen, or as a printer that prints the results.

[0020] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0021] Next, the boiler operation support method implemented by the boiler operation support device 10 of this embodiment will be described. The boiler operation support method of this embodiment can be implemented by the operation of this operation support device 10. The operation of the operation support device 10 can be realized by the processing of the processing circuit 11.

[0022] The processing circuit 11 performs a chemical thermodynamic analysis for each of several combustion conditions, including the air ratio and combustion reaction temperature, using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature on the surface of the heat transfer tube 5. The chemical thermodynamic analysis sets up a flow of multiple reactions that simulate the phenomena inside the boiler 1 according to the structure of the boiler 1, including the combustion reaction of the fuel and the condensation reaction of the combustion gas on the surface of the heat transfer tube 5, and performs a thermodynamic equilibrium calculation for each reaction.

[0023] Figure 3 shows an example of a chemical thermodynamic analysis flow for the structure of boiler 1 shown in Figure 1. Here, we will describe the case where boiler 1 is a soda recovery boiler installed in a paper mill. The soda recovery boiler contains black liquor discharged in the pulp manufacturing process as fuel. In this embodiment, a fuel mixture of black liquor and heavy oil is used. Hereafter, liquids and solids are collectively referred to as condensed phase substances.

[0024] Here, the processing circuit 11 has the elemental composition of the fuel fed into the boiler 1, the amount of fuel fed per unit time, the theoretical amount of air per unit time, and the condensation reaction temperature, which is a predetermined assumed temperature on the surface of the flue heat transfer tube 5, pre-input from the data acquisition device 16 and stored in the memory 13. In addition, the primary combustion reaction temperature, secondary combustion reaction temperature, primary air ratio, and secondary air ratio included in the combustion conditions are used as parameters, and the settable ranges for the primary combustion reaction temperature, secondary combustion reaction temperature, primary air ratio, and secondary air ratio are pre-input from the data acquisition device 16 and stored in the memory 13.

[0025] As shown in Figure 3, the processing circuit 11 first performs a primary combustion reaction analysis in the primary combustion region R1 in step S1. Specifically, by performing thermodynamic equilibrium calculations using the elemental composition of the fuel, the primary air ratio which determines the amount of primary air, and the primary combustion reaction temperature, the circuit estimates the composition of the primary combustion gas phase A produced by primary combustion, as well as the composition and deposition amount of the primary combustion reaction condensate phase A.

[0026] Next, in step S2, the processing circuit 11 performs a secondary combustion reaction analysis in the secondary combustion region R2. Specifically, by performing thermodynamic equilibrium calculations using the composition of the primary combustion gas phase A, the secondary air ratio which determines the amount of secondary air, and the secondary combustion reaction temperature, the circuit estimates the composition of the secondary combustion gas phase B produced by secondary combustion, as well as the composition and deposition amount of the secondary combustion reaction condensate phase material B.

[0027] Next, in step S3, the processing circuit 11 performs a condensation reaction analysis on the surface of the flue heat transfer tube 5. Specifically, by performing thermodynamic equilibrium calculations using the composition of the secondary combustion gas phase B and the condensation reaction temperature, which is a predetermined assumed temperature on the surface of the flue heat transfer tube 5, the composition and amount of combustion gas phase C on the surface of the flue heat transfer tube 5, and the composition of corrosive condensed phase material contained in the condensed phase C deposited on the surface of the flue heat transfer tube 5 are estimated.

[0028] The processing circuit 11 repeatedly performs the processes from steps S1 to S3 described above, changing the combustion conditions. That is, it repeatedly performs the processes from steps S1 to S3 described above, changing the values ​​of four parameters—primary combustion reaction temperature, secondary combustion reaction temperature, primary air ratio, and secondary air ratio—within their respective settable ranges. When changing these combustion conditions, it is sufficient that the value of at least one of the four parameters is changed. The amount of change for each parameter is predetermined. For example, the primary air ratio and secondary air ratio are changed in increments of 0.1 within their respective settable ranges. Also, the primary combustion reaction temperature and secondary combustion reaction temperature are changed in constant temperature increments within their respective settable ranges, provided that the secondary combustion reaction temperature is equal to or greater than the primary combustion reaction temperature.

[0029] Furthermore, the processing circuit 11 calculates the concentration of corrosive gases contained in the combustion gas phase C based on the composition and amount of the combustion gas phase C on the surface of the flue heat transfer tube 5 estimated in step S3. In this example, nitrogen oxides (NOx) are used as the corrosive gases. x ) as an example, NO x The concentration should be recorded.

[0030] Furthermore, the processing circuit 11 calculates the smelt recovery rate based on the composition and precipitate amount of primary combustion reaction condensate phase substance A estimated in step S1 and the composition and precipitate amount of secondary combustion reaction condensate phase substance B estimated in step S2. The smelt recovery rate indicates the proportion of sodium sulfate (Na2SO4) contained in black liquor that is recovered as sodium sulfide (Na2S). If the precipitate amount of Na2S is x [mol] and the precipitate amount of Na2SO4 is y [mol], it can be calculated using the following formula. Smelt recovery rate (%) = [x / (x+y)] × 100 The calculation of the corrosive gas concentration and the calculation of the smelt recovery rate may be performed each time a cycle of processing from step S1 to step S3 is completed, or it may be performed after the repetition of processing from step S1 to step S3 is completed.

[0031] Furthermore, the processing circuit 11 generates analytical data corresponding to each combustion condition, consisting of data including the composition of the corrosive condensed phase substance estimated in step S3, the concentration of the corrosive gas mentioned above, and the smelt recovery rate. In other words, it generates point cloud data consisting of a collection of multiple analytical data corresponding to multiple different combustion conditions.

[0032] Next, the processing circuit 11 searches the point cloud data for analysis data in which the composition of the corrosive condensed phase material satisfies the conditions for suppressing corrosion of the heat transfer tube 5 surface, the concentration of the corrosive gas is below a predetermined concentration, and the smelt recovery rate is above a predetermined value. The circuit then performs an optimization calculation to output the combustion conditions corresponding to the analysis data. The above-mentioned conditions for suppressing corrosion of the heat transfer tube 5 surface include, for example, the composition of the corrosive condensed phase material having a melting point that exceeds a predetermined assumed temperature of the heat transfer tube 5 surface.

[0033] The above content will be explained in more detail with reference to Figures 4 to 7. Figures 4 and 5 are phase diagrams plotting a portion of the analysis data for an example of the composition of corrosive condensed phase material contained in condensed phase C estimated in each step S3 when steps S1 to S3 in chemical thermodynamic analysis are repeated. In Figures 4 and 5, each circled number corresponds to one analysis data, and those with the same number correspond to the same analysis data, with the center of the circled number being the position where that data is plotted. Hereafter, the data with the circled number z (z is from 1 to 10) will be referred to as the analysis data with number z.

[0034] In the phase diagram of Figure 4, isotherms of the melting point are shown by curves, illustrating the relationship between the composition of the corrosive condensed phase material, which contains sodium and potassium chlorides and sulfates, and its melting point. In the phase diagram of Figure 4, corner A consists entirely of NaCl, corner B consists entirely of KCl, corner C consists entirely of Na2SO4, and corner D consists entirely of K2SO4. That is, the horizontal axis represents the ratio of Na to K contained in the corrosive condensed phase material; for example, at side CA, Na is 100% and K is 0%, and at side BD, Na is 0% and K is 100%. The vertical axis represents the ratio of Cl2 to SO4 contained in the corrosive condensed phase material; for example, at side AB, Cl2 is 100% and SO4 is 0%, and at side DC, Cl2 is 0% and SO4 is 100%. Na, K, Cl, and S are corrosion-involved elements found in fuel.

[0035] Furthermore, the phase diagram in Figure 5 shows isotherms of the melting point as curves, illustrating the relationship between the composition of the corrosive condensed phase material, which contains sodium and potassium chlorides and carbonates respectively, and its melting point. In the phase diagram in Figure 5, corner E consists entirely of KCl, corner F consists entirely of K2CO3, corner G consists entirely of NaCl, and corner H consists entirely of Na2CO3. In other words, the horizontal axis represents the ratio of Cl2 to CO3 contained in the corrosive condensed phase material, and the vertical axis represents the ratio of Na to K contained in the corrosive condensed phase material.

[0036] In Figure 4, the range of melting points below 600°C includes analysis data numbers 4, 7, and 8, and in Figure 5, the range of melting points below 600°C includes analysis data numbers 1 and 4. In the optimization calculation, the condition for suppressing corrosion on the surface of the heat transfer tube 5 is set to a composition in which the melting point of the corrosive condensed phase material exceeds the assumed temperature of the surface of the heat transfer tube 5. If the assumed temperature of the surface of the heat transfer tube 5 is 600°C, then the analysis data numbers 2, 3, 5, 6, 9, and 10, excluding numbers 1, 4, 7, and 8, satisfy the condition for suppressing corrosion on the surface of the heat transfer tube 5.

[0037] Figure 6 shows the smelt recovery rate on the horizontal axis and the corrosive gas NO on the vertical axis. x This figure plots the analysis data on a graph representing concentration. Here, in the optimization calculation, NO x When searching for analytical data where the concentration is below the predetermined concentration P1 and the smelt recovery rate is 80% or higher, NO x The analysis data for numbers 2, 4, 6, 8, and 10 are relevant because the concentration is within range a and the smelt recovery rate is within range b.

[0038] Therefore, in the optimization calculation, the conditions for suppressing corrosion on the surface of the heat transfer tube 5 are met, and NO x Analysis data with a concentration of P1 or less and a smelt recovery rate of 80% or more are the analysis data numbered 2, 6, and 10. Here, a smelt recovery rate of 80% or more is used as a condition for the smelt recovery rate in the optimization calculation, but this is just an example, and it can be set arbitrarily to, for example, 90% or more, 95% or more, etc.

[0039] Figure 7 shows the combustion conditions corresponding to the analysis data numbers 1 to 10. Figure 7 shows two graphs: one with the primary combustion reaction temperature on the horizontal axis and the primary air ratio on the vertical axis, plotting the analysis data on that graph, and another with the secondary combustion reaction temperature on the horizontal axis and the secondary air ratio on the vertical axis, plotting the analysis data on that graph.

[0040] Here, the analysis data for numbers 2, 6, and 10 within the range enclosed by the dashed lines r1 and r2 are the analysis data searched in the optimization calculation, and the combustion conditions, including the primary combustion reaction temperature, primary air ratio, secondary combustion reaction temperature, and secondary air ratio, can be read for each of the analysis data for numbers 2, 6, and 10. The processing circuit 11 may output these combustion conditions numerically to the output device 17 for display, or it may output and display them to the output device 17 as a graph as shown in Figure 7. In this case, the range that includes the analysis data for numbers 2, 6, and 10 but does not include other analysis data may be enclosed by the dashed lines r1 and r2. Also, the analysis data other than numbers 2, 6, and 10 may not be displayed.

[0041] In this way, combustion conditions for boiler 1 that can mitigate the corrosive environment and improve the smelt recovery rate can be determined and output.

[0042] Furthermore, by informing the boiler 1 operator of the combustion conditions corresponding to the analysis data numbers 2, 6, and 10 output from this operation support device 10, it becomes possible to improve the smelt recovery rate and mitigate the corrosive environment through operational adjustments, regardless of the operator's skills.

[0043] Furthermore, in this embodiment, boiler 1 is a soda recovery boiler, and the smelt recovery rate was considered when performing the optimization calculation. However, if boiler 1 is not a soda recovery boiler, the smelt recovery rate does not need to be considered. In this case, since it is not necessary to calculate the smelt recovery rate, it is not necessary to estimate the composition and precipitate amount of primary combustion reaction condensate phase material A in step S1, and it is not necessary to estimate the composition and precipitate amount of secondary combustion reaction condensate phase material B in step S2. Also, the smelt recovery rate is not included in each analysis data of the point cloud data. Even in this case, it is possible to determine and output the combustion conditions of boiler 1 that can realize the mitigation of the corrosive environment. In addition, other indicators may be used instead of the smelt recovery rate.

[0044] Furthermore, although this embodiment describes the case where boiler 1 is a two-stage combustion boiler as an example, it may also be a three-stage or more combustion boiler. For example, in the case of a three-stage combustion boiler, a tertiary air supply port is provided further downstream of the secondary air supply port in the gas flow path. In this case, in Figure 3, after step S2, in which the secondary combustion reaction analysis is performed, a step of performing a tertiary combustion reaction analysis is inserted, in which a thermodynamic equilibrium calculation is performed using the composition of the secondary combustion gas phase, the tertiary air ratio, and the tertiary combustion reaction temperature. After this, step S3 is performed, in which a condensation reaction analysis is performed on the surface of the flue heat transfer tube 5, in which a thermodynamic equilibrium calculation is performed using the composition of the tertiary combustion gas phase and the condensation reaction temperature, which is the assumed temperature of the surface of the flue heat transfer tube 5.

[0045] In other words, when the boiler is a soda recovery boiler, and n is an integer of 2 or more, the processing circuit 11 sets up a flow of multiple reactions, including the primary combustion reaction, the nth combustion reaction, and the condensation reaction of the combustion gas on the surface of the heat transfer tubes. The processing circuit 11 then performs thermodynamic equilibrium calculations for the primary combustion reaction using the elemental composition of the fuel, the primary air ratio included in the combustion conditions, and the primary combustion reaction temperature to estimate the composition of the primary combustion gas phase, the composition of the condensed phase material of the primary combustion reaction, and the amount of its precipitation.

[0046] Furthermore, when k is an integer from 2 to n, the processing circuit 11 performs thermodynamic equilibrium calculations for the k-th combustion reaction using the composition of the (k-1)th combustion gas phase estimated for the (k-1)th combustion reaction, the k-th air ratio included in the combustion conditions, and the k-th combustion reaction temperature. This allows the circuit to estimate the composition of the k-th combustion gas phase, the composition of the k-th combustion reaction condensate phase, and the amount of its precipitate.

[0047] Furthermore, the processing circuit 11 performs thermodynamic equilibrium calculations for the condensation reaction on the surface of the heat transfer tube using the composition of the nth-order combustion gas phase and the assumed temperature of the heat transfer tube surface to estimate the composition of the combustion gas phase and its amount produced on the surface of the heat transfer tube, as well as the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube.

[0048] Furthermore, the processing circuit 11 calculates the concentration of corrosive gas contained in the combustion gas phase based on the composition and generation amount of the combustion gas phase on the surface of the heat transfer tube.

[0049] Furthermore, the processing circuit 11 calculates the smelt recovery rate based on the composition and precipitation amount of the primary combustion reaction condensed phase substance and the composition and precipitation amount of the k-th combustion reaction condensed phase substance. That is, the smelt recovery rate is calculated based on the composition and precipitation amount of the condensed phase substance in each combustion reaction from the primary combustion reaction to the n-th combustion reaction.

[0050] Then, the processing circuit 11 generates analysis data including the composition of the corrosive condensed phase substance, the concentration of the corrosive gas, and the smelt recovery rate as one of the analysis data in the point cloud data. Then, by repeatedly changing the values of the primary air ratio, the primary combustion reaction temperature, the k-th air ratio, and the k-th combustion reaction temperature included in the combustion conditions within their respective predetermined ranges, point cloud data is generated.

[0051] Next, the processing circuit 11 searches for analysis data in the point cloud data that satisfies the conditions related to the suppression of corrosion on the surface of the heat transfer tube, and in which the concentration of the corrosive gas is below a predetermined concentration and the smelt recovery rate is above a predetermined value, and performs an optimization calculation to output the combustion conditions corresponding to the analysis data.

[0052] On the other hand, when the boiler is not a soda recovery boiler, the smelt recovery rate may not be considered. In this case, since there is no need to calculate the smelt recovery rate, for the primary combustion reaction, it is not necessary to estimate the composition and precipitation amount of the primary combustion reaction condensed phase substance, and for the k-th combustion reaction, it is not necessary to estimate the composition and precipitation amount of the k-th combustion reaction condensed phase substance. Also, in this case, the smelt recovery rate is not included in each analysis data of the point cloud data.

[0053] In the above embodiment, nitrogen oxides (NO x ) are exemplified as the corrosive gas, the NO x concentration is calculated, and in the optimization calculation, NO xThe condition is that the concentration must be below a predetermined concentration, but this is not the only condition. For example, hydrogen sulfide (H2S) could be used as the corrosive gas, the H2S concentration could be calculated, and the optimization calculation could be conditional on the H2S concentration being below a predetermined concentration. Alternatively, sulfur oxides (SO4) could be used as the corrosive gas. x ) targeting SO x The concentration is calculated, and in the optimization calculation, SO x The condition may be that the concentration is below a predetermined level. Two or more of the following corrosive gases may be targeted: nitrogen oxides, hydrogen sulfide, and sulfur oxides.

[0054] [Variation] In the above embodiment, the conditions for suppressing corrosion of the heat transfer tube surface in the optimization calculation were set to a composition in which the melting point of the corrosive condensed phase material exceeds a predetermined assumed temperature of the heat transfer tube surface, but this is not limited to this. Corrosion tests and the like show that under conditions assumed in actual equipment, the greater the amount of corrosive condensed phase material precipitated, the greater the corrosion rate tends to be. For example, the conditions for suppressing corrosion of the heat transfer tube surface may be set to such that the composition of the corrosive condensed phase material and its precipitated amount correspond to a corrosion rate of less than or equal to a predetermined rate in the corrosion rate-related information described later.

[0055] In this case, in step S3, the processing circuit 11 estimates the composition and amount of combustion gas phase C on the surface of the flue heat transfer tube 5, and the composition and amount of corrosive condensed phase material contained in the condensed phase C deposited on the surface of the flue heat transfer tube 5.

[0056] Furthermore, in step S3, multiple data points corresponding to various compositions and precipitation amounts of the corrosive condensed phase substance and the corrosion rate are stored in memory 13 in advance as corrosion rate-related information. For example, in this case, multiple test pieces reflecting various compositions and precipitation amounts of the corrosive condensed phase substance are prepared and a corrosion test is performed. In this corrosion test, the prepared test pieces are exposed for a predetermined time in a predetermined gas atmosphere at a predetermined temperature, for example, 600°C, which is the assumed temperature of the surface of the flue heat transfer tube 5. The amount of corrosion thinning is determined for each test piece before and after the test, and the amount of corrosion thinning is converted into a corrosion rate. Then, multiple data points corresponding to various compositions and precipitation amounts of the corrosive condensed phase substance and the corrosion rate are stored in memory 13 in advance as corrosion rate-related information.

[0057] Then, the point cloud data is generated as a collection of analytical data, which includes the composition and amount of corrosive condensed phase material corresponding to each combustion condition, as well as the concentration of corrosive gases.

[0058] Then, in the optimization calculation, the system searches for analysis data from the point cloud data in which the composition and precipitation amount of corrosive condensed phase material correspond to a corrosion rate of less than or equal to a predetermined rate in the corrosion rate-related information, and in which the concentration of corrosive gas is less than or equal to a predetermined concentration, and outputs the combustion conditions corresponding to that analysis data.

[0059] Furthermore, in the above modified example, instead of corrosion rate-related information, a corrosion rate relational equation showing the relationship between various compositions and precipitation amounts of corrosive condensed phase substances obtained by corrosion tests and the corrosion rate may be derived and stored in memory 13 in advance. In this case, during the optimization calculation, analysis data is searched from the point cloud data for which the corrosion rate derived from the corrosion rate relational equation is less than or equal to a predetermined rate, and for which the concentration of corrosive gas is less than or equal to a predetermined concentration, and the combustion conditions corresponding to the analysis data are output.

[0060] In the above embodiment, the fuel was kept constant, but even when, for example, multiple types of fuel are mixed and the mixing ratio is changed, the same method can be used to output desirable combustion conditions. For example, when mixing biomass fuel and fossil fuel, the optimization calculation may be performed with the condition that the mixing ratio of fossil fuel be kept below a predetermined ratio within a predetermined range, and the combustion conditions may be output. Alternatively, considering fuel costs, the optimization calculation may be performed with the condition that the mixing ratio of multiple types of fuel be set to a ratio that results in fuel costs below a predetermined value, and the combustion conditions may be output.

[0061] From the above description, many improvements and other embodiments of the disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the disclosure. The details of its structure and / or function can be substantially modified without departing from the spirit of the disclosure.

[0062] (Summary of this disclosure) A boiler operation support device according to a first aspect of this disclosure is a boiler operation support device in which heat transfer tubes are installed in a passage through which combustion gas produced by the combustion of fuel passes, and comprises a processing circuit, which performs a chemical thermodynamic analysis on each of a plurality of combustion conditions, including air ratio and combustion reaction temperature, using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature of the heat transfer tube surface, thereby estimating the composition of the combustion gas phase on the heat transfer tube surface and the amount thereof generated, as well as the composition of corrosive condensed phase material deposited on the heat transfer tube surface, or the composition of the corrosive condensed phase material and the amount thereof deposited. The system determines the composition of the combustion gas phase on the heat transfer tube surface and calculates the concentration of corrosive gas on the heat transfer tube surface based on the composition of the combustion gas phase on the heat transfer tube surface and the amount of gas generated thereon. It then generates point cloud data consisting of a collection of data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of gas precipitated thereon, and the concentration of the corrosive gas, corresponding to each of the combustion conditions. From the point cloud data, it searches for data where the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of gas precipitated thereon, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of the corrosive gas is below a predetermined concentration. The system then performs an optimization calculation to output the combustion conditions corresponding to such data.

[0063] This configuration allows for the extraction of data from point cloud data where the composition of corrosive condensed phase material, or the composition and deposition amount of corrosive condensed phase material, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of corrosive gases is below a predetermined concentration. By outputting the combustion conditions corresponding to this data, combustion conditions that mitigate the corrosive environment of the boiler can be generated. By informing the boiler operator of these combustion conditions, optimal boiler operation adjustments become possible, independent of the operator's skills.

[0064] A boiler operation support device according to a second aspect of this disclosure is a boiler operation support device according to a first aspect, wherein the processing circuit sets up a flow of multiple reactions that simulates phenomena inside the boiler having a structure that performs primary to nth combustion to burn fuel, when n is an integer of 2 or more, in order to perform the chemical thermodynamic analysis, and the flow of multiple reactions includes primary to nth combustion reactions and condensation reactions of combustion gas on the surface of the heat transfer tubes, and estimates the composition of the primary combustion gas phase by performing thermodynamic equilibrium calculations for the primary combustion reaction using the elemental composition of the fuel and the primary air ratio and primary combustion reaction temperature included in the combustion conditions, when k is an integer from 2 to n, estimates the composition of the kth combustion gas phase by performing thermodynamic equilibrium calculations for the kth combustion reaction using the composition of the (k-1)th combustion gas phase estimated for the (k-1)th combustion reaction and the kth air ratio and kth combustion reaction temperature included in the combustion conditions. The process involves estimating the composition and performing thermodynamic equilibrium calculations for the condensation reaction using the composition of the nth-order combustion gas phase and a predetermined assumed temperature on the surface of the heat transfer tube to estimate the composition of the combustion gas phase on the surface of the heat transfer tube and the amount produced therefrom, the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube, or the composition of the corrosive condensed phase material and the amount deposited therefrom. Based on the composition of the combustion gas phase on the surface of the heat transfer tube and the amount produced therefrom, the concentration of the corrosive gas contained in the combustion gas phase is calculated. Data including the composition of the corrosive condensed phase material, or the composition of the corrosive condensed phase material and the amount deposited therefrom, and the concentration of the corrosive gas is generated as one of the point cloud data. This process is repeated by changing the values ​​of the primary air ratio, primary combustion reaction temperature, k-order air ratio, and k-order combustion reaction temperature included in the combustion conditions within predetermined ranges, thereby generating the point cloud data.

[0065] With this configuration, in the case of an n-stage combustion boiler, combustion conditions that mitigate the corrosive environment of the boiler are output, and these combustion conditions can be communicated to the operator.

[0066] A boiler operation support device according to a third aspect of this disclosure is a boiler operation support device according to a first aspect, wherein the boiler is a soda recovery boiler containing black liquor as fuel, and the processing circuit is a flow of multiple reactions that simulates phenomena inside the boiler having a structure in which primary to nth combustion is performed to burn fuel, when n is an integer of 2 or more, in order to perform the chemical thermodynamic analysis, and sets the flow of multiple reactions including primary to nth combustion reactions and condensation reactions of combustion gases on the surface of the heat transfer tubes, and sets the elemental composition of the fuel and the combustion conditions for the primary combustion reaction. By performing thermodynamic equilibrium calculations using the primary air ratio and primary combustion reaction temperature included in the above, the composition of the primary combustion gas phase, the composition of the primary combustion reaction condensate phase material and its deposition amount are estimated. When k is an integer from 2 to n, for the k-th combustion reaction, by performing thermodynamic equilibrium calculations using the composition of the (k-1)th combustion gas phase estimated for the (k-1)th combustion reaction, and the k-th air ratio and k-th combustion reaction temperature included in the above combustion conditions, the composition of the k-th combustion gas phase, the composition of the k-th combustion reaction condensate phase material and its deposition amount are estimated. For the above condensation reaction, the composition of the n-th combustion gas phase By performing thermodynamic equilibrium calculations using a predetermined assumed temperature on the surface of the heat transfer tube, the composition and amount of the combustion gas phase on the surface of the heat transfer tube, the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube, or the composition and amount of the corrosive condensed phase material deposited is estimated. Based on the composition and amount of the combustion gas phase on the surface of the heat transfer tube, the concentration of the corrosive gas contained in the combustion gas phase is calculated. Based on the composition and amount of the primary combustion reaction condensed phase material and the composition and amount of the k-th combustion reaction condensed phase material, sodium sulfate and sulfide The smelt recovery rate, which is the ratio of the amount of sodium sulfide precipitated to the amount of sodium precipitated, is calculated, and data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its precipitated amount, the concentration of the corrosive gas, and the smelt recovery rate is generated as one of the point cloud data by repeatedly changing the values ​​of the primary air ratio, the primary combustion reaction temperature, the k-th air ratio, and the k-th combustion reaction temperature included in the combustion conditions within their respective predetermined ranges, thereby generating the point cloud data, and in the optimization calculation,From the point cloud data, data is searched for that satisfies the conditions for suppressing corrosion on the heat transfer tube surface, where the concentration of the corrosive gas is below a predetermined concentration, and the smelt recovery rate is above a predetermined value. The combustion conditions corresponding to such data are then output.

[0067] With this configuration, in the case of an n-stage combustion type soda recovery boiler, combustion conditions that can mitigate the corrosive environment of the boiler and improve the smelt recovery rate are output, and these combustion conditions can be communicated to the operator.

[0068] A boiler operation support device according to a fourth aspect of this disclosure is a boiler operation support device according to any of the first to third aspects, wherein the condition for suppressing corrosion of the heat transfer tube surface is that the composition of the corrosive condensed phase substance has a melting point that exceeds a predetermined assumed temperature of the heat transfer tube surface.

[0069] With this configuration, by setting the conditions for suppressing corrosion of the heat transfer tube surface to a composition in which the corrosive condensed phase substance has a melting point exceeding a predetermined assumed temperature on the heat transfer tube surface, it is possible to output combustion conditions in which the corrosive condensed phase substance does not melt on the surface of the heat transfer tube, that is, combustion conditions that prevent corrosion of the heat transfer tube due to the melting of the corrosive condensed phase substance.

[0070] A boiler operation support method according to a fifth aspect of this disclosure is a boiler operation support method in which heat transfer tubes are installed in a passage through which combustion gas produced by the combustion of fuel passes, wherein for each of a plurality of combustion conditions including air ratio and combustion reaction temperature as combustion conditions, a chemical thermodynamic analysis is performed using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature of the heat transfer tube surface to estimate the composition of the combustion gas phase on the heat transfer tube surface and the amount thereof generated, as well as the composition of corrosive condensed phase material deposited on the heat transfer tube surface, or the composition of the corrosive condensed phase material and the amount thereof deposited, and the heat transfer tube An optimization calculation is performed to calculate the concentration of corrosive gas on the surface of the heat transfer tube based on the composition of the combustion gas phase on the surface and the amount generated thereof, generate point cloud data consisting of a collection of data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of precipitation thereof, and the concentration of the corrosive gas, corresponding to each of the combustion conditions, search for data from the point cloud data in which the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and the amount of precipitation thereof, satisfies the conditions for suppressing corrosion on the surface of the heat transfer tube, and the concentration of the corrosive gas is below a predetermined concentration, and output the combustion conditions corresponding to such data.

[0071] This method searches for data within point cloud data where the composition of corrosive condensed phase material, or the composition and deposition amount of corrosive condensed phase material, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of corrosive gas is below a predetermined concentration. By outputting the combustion conditions corresponding to this data, combustion conditions that mitigate the corrosive environment of the boiler can be output. By informing the boiler operator of these combustion conditions, optimal boiler operation adjustments become possible, independent of the operator's skills. [Explanation of symbols]

[0072] 1 Boiler 5 Heat transfer tubes 10 Boiler operation support devices 11 Processing Circuit

Claims

1. A boiler operation support device in which heat transfer tubes are installed in a passage through which combustion gases produced by the burning of fuel pass, Equipped with a processing circuit, The aforementioned processing circuit is For each of the multiple combustion conditions, including the air ratio and combustion reaction temperature, a chemical thermodynamic analysis is performed using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature of the heat transfer tube surface. This analysis estimates the composition and amount of the combustion gas phase on the heat transfer tube surface, as well as the composition of the corrosive condensed phase material deposited on the heat transfer tube surface, or the composition and amount of the corrosive condensed phase material deposited. Based on the composition of the combustion gas phase on the surface of the heat transfer tube and the amount generated therefrom, the concentration of corrosive gas on the surface of the heat transfer tube is calculated. Point cloud data is generated consisting of a collection of data including the composition of the corrosive condensed phase substance corresponding to each of the aforementioned combustion conditions, or the composition of the corrosive condensed phase substance and its deposition amount, and the concentration of the corrosive gas. From the point cloud data, the system searches for data where the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its deposition amount, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of the corrosive gas is below a predetermined concentration. The system then performs an optimization calculation to output the combustion conditions corresponding to the data. A boiler operation support device.

2. The aforementioned processing circuit is In order to perform the aforementioned chemical thermodynamic analysis, when n is an integer of 2 or more, a flow of multiple reactions is set that simulates the phenomena inside the boiler having a structure in which primary combustion to nth combustion is performed to burn fuel, and the flow of multiple reactions includes the primary combustion reaction to the nth combustion reaction and the condensation reaction of combustion gas on the surface of the heat transfer tube, Regarding the primary combustion reaction, the composition of the primary combustion gas phase is estimated by performing thermodynamic equilibrium calculations using the elemental composition of the fuel, the primary air ratio included in the combustion conditions, and the primary combustion reaction temperature. When k is an integer from 2 to n, the composition of the k-th combustion gas phase is estimated for the k-th combustion reaction by performing thermodynamic equilibrium calculations using the composition of the (k-1)th combustion gas phase estimated for the (k-1)th combustion reaction, and the k-th air ratio and k-th combustion reaction temperature included in the combustion conditions. With respect to the condensation reaction, thermodynamic equilibrium calculations are performed using the composition of the nth-order combustion gas phase and a predetermined assumed temperature on the surface of the heat transfer tube to estimate the composition of the combustion gas phase on the surface of the heat transfer tube and the amount produced therein, as well as the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube, or the composition of the corrosive condensed phase material and the amount deposited therein. Based on the composition of the combustion gas phase on the surface of the heat transfer tube and the amount of gas generated therefrom, the concentration of the corrosive gas contained in the combustion gas phase is calculated. The method for generating point cloud data includes the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its precipitate amount, and the concentration of the corrosive gas, by repeatedly changing the values ​​of the primary air ratio, primary combustion reaction temperature, k-th order air ratio, and k-th order combustion reaction temperature included in the combustion conditions within predetermined ranges, thereby generating the point cloud data. The boiler operation support device according to claim 1.

3. The aforementioned boiler is a soda recovery boiler that contains black liquor as fuel, The aforementioned processing circuit is In order to perform the aforementioned chemical thermodynamic analysis, when n is an integer of 2 or more, a flow of multiple reactions is set that simulates the phenomena inside the boiler having a structure in which primary combustion to nth combustion is performed to burn fuel, and the flow of multiple reactions includes the primary combustion reaction to the nth combustion reaction and the condensation reaction of combustion gas on the surface of the heat transfer tube, Regarding the primary combustion reaction, thermodynamic equilibrium calculations are performed using the elemental composition of the fuel, the primary air ratio included in the combustion conditions, and the primary combustion reaction temperature to estimate the composition of the primary combustion gas phase, the composition of the primary combustion reaction condensate phase material, and the amount of its precipitation. When k is an integer from 2 to n, for the k-th combustion reaction, thermodynamic equilibrium calculations are performed using the composition of the (k-1)th combustion gas phase estimated for the (k-1)th combustion reaction, the k-th air ratio included in the combustion conditions, and the k-th combustion reaction temperature. This allows for the estimation of the composition of the k-th combustion gas phase, the composition of the k-th combustion reaction condensate phase, and its deposition amount. With respect to the condensation reaction, thermodynamic equilibrium calculations are performed using the composition of the nth-order combustion gas phase and a predetermined assumed temperature on the surface of the heat transfer tube to estimate the composition of the combustion gas phase on the surface of the heat transfer tube and the amount produced therein, as well as the composition of the corrosive condensed phase material deposited on the surface of the heat transfer tube, or the composition of the corrosive condensed phase material and the amount deposited therein. Based on the composition of the combustion gas phase on the surface of the heat transfer tube and the amount of gas generated therefrom, the concentration of the corrosive gas contained in the combustion gas phase is calculated. Based on the composition and amount of precipitated primary combustion reaction condensate and the composition and amount of precipitated k-th generation combustion reaction condensate, the smelt recovery rate, which is the ratio of the amount of precipitated sodium sulfide to the amount of precipitated sodium sulfate and sodium sulfide, is calculated. The data including the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its precipitate amount, the concentration of the corrosive gas, and the smelt recovery rate is generated as one of the point cloud data by repeatedly changing the values ​​of the primary air ratio, the primary combustion reaction temperature, the k-th order air ratio, and the k-th order combustion reaction temperature included in the combustion conditions within predetermined ranges, thereby generating the point cloud data. In the optimization calculation, data is searched from the point cloud data that satisfies the conditions for suppressing corrosion on the heat transfer tube surface, where the concentration of the corrosive gas is below a predetermined concentration, and the smelt recovery rate is above a predetermined value, and the combustion conditions corresponding to such data are output. The boiler operation support device according to claim 1.

4. The condition for suppressing corrosion on the surface of the heat transfer tube is that the composition of the corrosive condensed phase material has a melting point that exceeds a predetermined assumed temperature on the surface of the heat transfer tube. A boiler operation support device according to any one of claims 1 to 3.

5. A method for supporting the operation of a boiler in which heat transfer tubes are installed in a passage through which combustion gases produced by the burning of fuel pass, For each of the multiple combustion conditions, including the air ratio and combustion reaction temperature, a chemical thermodynamic analysis is performed using the elemental composition of the fuel, the air ratio and combustion reaction temperature included in the combustion conditions, and a predetermined assumed temperature of the heat transfer tube surface. This analysis estimates the composition and amount of the combustion gas phase on the heat transfer tube surface, as well as the composition of the corrosive condensed phase material deposited on the heat transfer tube surface, or the composition and amount of the corrosive condensed phase material deposited. Based on the composition of the combustion gas phase on the surface of the heat transfer tube and the amount generated therefrom, the concentration of corrosive gas on the surface of the heat transfer tube is calculated. Point cloud data is generated consisting of a collection of data including the composition of the corrosive condensed phase substance corresponding to each of the aforementioned combustion conditions, or the composition of the corrosive condensed phase substance and its deposition amount, and the concentration of the corrosive gas. From the point cloud data, the system searches for data where the composition of the corrosive condensed phase substance, or the composition of the corrosive condensed phase substance and its deposition amount, satisfies the conditions for suppressing corrosion on the heat transfer tube surface, and the concentration of the corrosive gas is below a predetermined concentration. The system then performs an optimization calculation to output the combustion conditions corresponding to the data. Boiler operation support methods.

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