Control method and control system for fuel switching of a gas boiler

Abstract

The embodiment of the present application provides a control method and a control system for fuel switching of a gas boiler, and belongs to the technical field of boilers. The control method for fuel switching of the gas boiler comprises the following steps: obtaining a gas supply signal of a gas supply device, the gas supply device being connected to a boiler dynamic operation system through a gas supply pipeline to supply gas to a boiler in the boiler dynamic operation system; and when the gas supply signal shows that the gas supply device abnormally supplies gas, the opening degree of a first group of control valves on a main gas supplement pipeline is controlled to control the main gas supplement pipeline to supply gas to the boiler in the boiler dynamic operation system. The complex combustion control and rapid switching of multiple main fuels can be realized, the stable operation of the boiler is maintained when upstream gas is abnormal, the smooth production of downstream ethylene devices is ensured, and the unplanned shutdown is greatly reduced; the material loss, equipment life loss and excessive emission of pollutants caused by frequent start and stop are saved.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, and more specifically to a control method and control system for switching fuels in a gas-fired boiler. Background Technology

[0002] Boilers release a large amount of heat through fuel combustion in the furnace. Water in the boiler drum absorbs radiant heat from the furnace and exchanges heat with the flue gas through convective circulation, ultimately producing high-temperature, high-pressure steam. A stable supply of boiler fuel and the stability of its calorific value are key factors affecting the stable operation of the boiler. With increasing awareness of environmental protection, there is a growing trend of using the high-temperature environment of boilers to co-fire solid waste, recover waste gas, sludge, biomass, etc. Utilizing the combustion heat of these waste gas resources saves fuel and also decomposes hazardous waste at high temperatures. Co-firing is usually carried out in coal-fired boilers, and the co-fired fuel only accounts for a small portion of the main fuel, so it does not have a significant impact on the stable operation of the boiler.

[0003] Because the composition of the main fuels and blended fuels varies greatly, their calorific values ​​differ significantly. Therefore, in the event of a sudden interruption of a fuel supply, other fuels need to be replenished promptly to provide sufficient combustion heat in order to ensure the boiler continues operation. Currently, the response during boiler operation mainly relies on manual intervention by operators, which involves frequent operations and makes coordinated control difficult. Summary of the Invention

[0004] The purpose of this invention is to provide a control method for switching fuels in a gas-fired boiler, which can quickly and accurately achieve fuel switching in a gas-fired boiler.

[0005] To achieve the above objectives, embodiments of the present invention provide a control method for switching fuels in a gas-fired boiler. The control method for switching fuels in a gas-fired boiler includes: acquiring a gas supply signal from a gas supply device, wherein the gas supply device is connected to a dynamic boiler operation system via a gas supply pipeline to supply gas to the boiler in the dynamic boiler operation system; and when the gas supply signal indicates an abnormal gas supply from the gas supply device, controlling the opening of a first set of control valves on the main gas supply pipeline to control the main gas supply pipeline to supply gas to the boiler in the dynamic boiler operation system.

[0006] Optionally, the gas supply device is a POX device, which includes at least two fuel production devices. When the gas supply signal indicates that the gas supply device is abnormal, controlling the opening of the first group of control valves includes: when the gas supply signal indicates that one of the fuel production devices of the POX device is abnormal, controlling the first main valve PV-2001B of the first group of control valves to an automatic control opening mode.

[0007] Optionally, the step of controlling the opening of the first group of control valves when the gas supply signal indicates an abnormal gas supply to the gas supply device further includes: when the gas supply signal indicates an abnormal gas supply to the two fuel production units of the POX device, controlling the first auxiliary valve PV-2001A of the first group of control valves to a manual control opening mode; controlling the first main valve PV-2001B to a preset opening degree, and then controlling the first main valve PV-2001B to an automatic control opening mode; and determining the flow rate of the first auxiliary valve PV-2001A through the monitored flow rate of the boiler dynamic operation system. The flow feedforward prediction value of the main valve PV-2001B and the flow feedforward prediction value of the first auxiliary valve PV-2001A are used to obtain the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A; and the opening of the first main valve PV-2001B and the opening of the first auxiliary valve PV-2001A are adjusted accordingly based on the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A.

[0008] Optionally, before controlling the first main valve PV-2001B to a preset opening degree, the control method for switching fuel in the gas-fired boiler further includes: when the gas supply signal indicates an abnormal gas supply to the two fuel production devices of the POX unit, acquiring the flow rate F1 indicated by the first flow measurement point FIC001, wherein the first flow measurement point FIC001 is arranged at the outlet pipe of the POX unit; calculating the flow rate F2 of the main gas supply pipe based on the flow rate F1; calculating the opening degree value V1 corresponding to the first main valve PV-2001B based on the flow rate F2 and the pressure-flow characteristic equation of the first main valve PV-2001B; and determining the preset opening degree by summing the difference V3 between the opening degree V1 and the current opening degree value V2 of the first main valve PV-2001B, after limiting the amplitude [5%, 20%], with the current opening value V2.

[0009] Optionally, determining the flow feedforward prediction value through the first main valve PV-2001B and the flow feedforward prediction value through the first auxiliary valve PV-2001A, and correspondingly obtaining the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A, includes: for the three-layer burner structure of each boiler in the boiler dynamic operation system, when the main supplementary gas ring flow control valve of each layer is open and the flow rate of the main supplementary gas ring supply pipeline is greater than a preset value, the flow rate value corresponding to the opening command of the main supplementary gas ring flow control valve is used as the flow feedforward prediction value of the corresponding layer. Each boiler includes a ring supply pipeline and 3*N gas pipelines, where N is the type of gas supplied. Each gas pipeline is equipped with a flow monitoring point, and the ring supply pipeline is equipped with... The flow control valve is used as follows: the sum of the flow feedforward prediction values ​​of each layer is used as the flow feedforward prediction value of the corresponding boiler; based on the sum Q of the flow feedforward prediction values ​​of each boiler, the correction coefficient X2, and the pressure-flow characteristic equation of the first auxiliary valve PV-2001A, the feedforward opening V4 of the first auxiliary valve PV-2001A is obtained, and the product of the feedforward opening V4 and the correction coefficient X3 is used as the opening feedforward prediction value of the first auxiliary valve PV-2001A; based on the sum Q of the flow feedforward prediction values ​​of each boiler model, the correction coefficient X2, and the pressure-flow characteristic equation of the first main valve PV-2001B, the feedforward opening V5 of the first main valve PV-2001B is obtained, and the product of the feedforward opening V5 and the correction coefficient X4 is used as the opening feedforward prediction value of the first main valve PV-2001B.

[0010] Optionally, when the gas supply signal indicates an abnormal gas supply to the two fuel production units of the POX device, the control method for switching fuels in the gas boiler further includes controlling the opening of a second set of control valves. A second set of control valves and a first pressure measuring point PIC101 are installed at a preset position at the inlet end of the main gas supply pipeline. The second set of control valves includes a second main valve PV-1001 and a second auxiliary valve PV-1005. Controlling the opening of the second set of control valves includes: controlling the second auxiliary valve PV-1005 to an automatic control opening mode, or controlling the second main valve PV-1001 to an automatic control opening mode. The system employs a degree-based mode; based on the monitored flow rate through the first set of control valves, it determines the flow rate feedforward prediction value of the second main valve PV-1001 and the flow rate feedforward prediction value of the second auxiliary valve PV-1005, and correspondingly obtains the opening degree feedforward prediction value of the second main valve PV-1001 and the opening degree feedforward prediction value of the second auxiliary valve PV-1005; and adjusts the opening degree of the second main valve PV-1001 and the second auxiliary valve PV-1005 accordingly based on the opening degree feedforward prediction values ​​of the second main valve PV-1001 and the second auxiliary valve PV-1005.

[0011] Optionally, controlling the opening of the second set of control valves further includes: when the second main valve PV-1001 is not in automatic control opening mode, recording the initial opening value V0 of the second main valve PV-1001; calculating the flow rate F6 passing through the second main valve PV-1001 according to the initial opening value V0 and the pressure-flow characteristic equation of the second main valve PV-1001; obtaining the corresponding final opening value V12 passing through the second main valve PV-1001 according to the flow rate F7 and the pressure-flow characteristic equation of the second main valve PV-1001, wherein within a preset time, the flow rate F6 passing through the second main valve PV-1001 increases to the flow rate F7 at a preset rate; and controlling the second main valve PV-1001 from the initial opening value V0 to the final opening value V12 within the preset time.

[0012] Optionally, determining the flow feedforward prediction values ​​of the second main valve PV-1001 and the second auxiliary valve PV-1005, and correspondingly obtaining the opening feedforward prediction values ​​of the second main valve PV-1001 and the second auxiliary valve PV-1005, includes: obtaining the opening value V7 of the first main valve PV-2001B and the opening value V6 of the first auxiliary valve PV-2001A; obtaining the flow rate F1 through the first main valve PV-2001B based on the opening value V7 and the pressure-flow characteristic equation of the first main valve PV-2001B; and obtaining the flow rate F1 through the first auxiliary valve PV-2001A based on the opening value V6 and the pressure-flow characteristic equation of the first auxiliary valve PV-2001A. The flow rate F2 of 1A; the sum of the flow rates F1 and F2 is taken as the total flow rate F3 through the first group of control valves; based on the total flow rate F3, the correction coefficient X5, and the pressure-flow characteristic equation of the second main valve PV-1001, the feedforward opening V8 of the second main valve PV-1001 is obtained, and the product of the feedforward opening V8 and the correction coefficient X7 is taken as the feedforward prediction value of the opening of the second main valve PV-1001; based on the total flow rate F3, the correction coefficient X6, and the pressure-flow characteristic equation of the second auxiliary valve PV-1005, the feedforward opening V9 of the second auxiliary valve PV-1005 is obtained, and the product of the feedforward opening V9 and the correction coefficient X8 is taken as the feedforward prediction value of the opening of the second auxiliary valve PV-1005.

[0013] This invention also provides a control system for switching fuels in a gas-fired boiler. The control system includes a gas supply device, a main gas supply pipeline, and a control device. The gas supply device is a POX device, which includes at least two fuel-generating devices. The POX device is connected to a dynamic boiler operating system via a pipeline to supply gas to the boiler in the dynamic boiler operating system. A first flow measurement point FIC001 is installed at the outlet pipeline of the POX device. The main gas supply pipeline is connected to the dynamic boiler operating system to supply gas to the boiler in the dynamic boiler operating system when the gas supply from the POX device is abnormal. A first set of control valves is arranged on the main gas supply pipeline, including a first main valve PV-2001B and a first auxiliary valve PV-2001A. The control device is used to control the POX device and / or the main gas supply pipeline to supply gas to the boiler in the dynamic boiler operating system according to the above-described control method for switching fuels in a gas-fired boiler.

[0014] Optionally, each boiler in the boiler dynamic operation system includes: a combustion chamber for chemical reactions, a radiation chamber, a steam drum, a flue gas convection heat exchanger, a superheater, an economizer, a fan, and a water supply system.

[0015] Optionally, each boiler in the boiler dynamic operation system includes a three-layer burner structure. Each boiler also includes a ring gas supply pipeline and 3*N gas pipelines, where N is the type of gas supplied. Each gas pipeline is equipped with a flow monitoring point, and the ring gas supply pipeline is equipped with a ring flow control valve.

[0016] Optionally, a second set of control valves and a first pressure measuring point PIC101 are provided at a preset position at the inlet end of the main gas supply pipeline. The second set of control valves includes a second main valve PV-1001 and a second auxiliary valve PV-1005. The main gas supply pipeline supplies gas through constant pressure control. The gas supply flow rate of the main gas supply pipeline is determined by the opening degree of the second set of control valves, the pipeline flow velocity, and the characteristics of the pipeline resistance.

[0017] Optionally, the control device is further configured to construct a corresponding pressure-flow characteristic equation based on the flow characteristic parameters of the first group of control valves and the second group of control valves.

[0018] Optionally, the control device is also used to perform bidirectional data interaction with the virtual DCS-based control model of the boiler dynamic operation system.

[0019] Through the above technical solutions, the embodiments of the present invention can achieve complex combustion control and rapid switching of multiple main fuels. In the event of upstream gas anomalies, it maintains stable boiler operation, ensuring stable production of downstream ethylene and other units, and significantly reducing unplanned shutdowns. It saves material losses, equipment lifespan losses, and excessive pollutant emissions caused by frequent start-ups and shutdowns, thereby bringing significant economic and social benefits. The embodiments of the present invention also provide a simulation model for boiler system control with a furnace containing the actual fuel chemical composition and combustion reaction. This simulation model includes a fuel gas pipeline network model system constructed based on the construction drawings of the fuel gas pipelines at the gas-fired boiler site. The dynamic response characteristics of the parameters in this simulation model closely match those of the actual unit. By continuously iterating and optimizing the fuel switching scheme of the gas-fired boiler in the simulation model, and introducing the pressure-flow characteristic equation (or valve characteristic curve) of the control valve into the control scheme, the flow rate and valve opening are predicted, achieving decoupled control and greatly improving the response speed of the gas control valves in the pipeline network. As shown above, actual measurements show that under extreme conditions where the syngas from the POX unit, which accounts for 60% of the normal operating calorific value, is suddenly interrupted, the gas-fired boiler fuel can complete automatic and rapid switching within 50 seconds. The implementation of this control scheme effectively ensures the stable operation of the plant's boiler system, thereby promoting a stable steam supply for the entire plant and minimizing the impact of an emergency shutdown of the POX unit on other steam-using units.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a schematic diagram illustrating the fuel classification of an example gas-fired boiler system;

[0023] Figure 2 This is a flowchart illustrating a control method for switching fuels in a gas-fired boiler, provided in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of an example fuel gas pipeline network model system;

[0025] Figure 4 This is a schematic diagram of a fuel distribution network model within the boundary area of ​​a single boiler.

[0026] Figure 5 This is a schematic diagram of an example single combustion furnace;

[0027] Figure 6This is a schematic diagram illustrating real-time data interaction in a boiler system based on a virtual DCS virtual controller.

[0028] Figure 7 This is a flowchart illustrating an example of a control method for switching fuels in a gas-fired boiler.

[0029] Figure 8 This is a schematic diagram illustrating the control flow of the second group of control valves; and

[0030] Figure 9 This is a schematic diagram of the control system for switching fuels in a gas-fired boiler provided in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 1. Blower 2. Air preheater

[0033] 3 Exhaust fan 4 Recirculation fan

[0034] 5 bellows 6 furnace

[0035] 7 Steam drums 8 Economizers

[0036] 9 superheaters 8 economizers

[0037] 101 POX device 102 Main gas supply pipeline

[0038] 103 Boiler Dynamic Operation System Detailed Implementation

[0039] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0040] Before explaining the embodiments of the present invention in detail, the gas-fired boiler system will be briefly described as follows.

[0041] Please refer to Figure 1 Taking four CG-410 / 13.0-Q type gas-fired boilers in a certain refining and chemical base, which are used in the supporting public works of an ethylene unit, to recover and reuse the tail gas of the process unit, as an example, the main fuels of this gas-fired boiler system are, for example, natural gas, post-ether C4, and POX syngas, while also co-firing tail gas from various process units, with up to 13 types of fuels. As shown in Table 1, due to the different components and calorific values ​​of the various fuels, coordinated control is difficult, and operation mainly relies on manual intervention by operators, resulting in frequent operations.

[0042] Table 1. Main Fuel Characteristics

[0043]

[0044]

[0045] As can be seen from the table above, the calorific values ​​of the above-mentioned fuels vary greatly due to their different compositions. Therefore, if a certain fuel is suddenly interrupted, in order to ensure that the boiler does not stop, it is necessary to replenish the corresponding natural gas in a short period of time to provide sufficient combustion heat.

[0046] Therefore, the following challenges and risks exist during the operation of this type of boiler system:

[0047] 1) The original control system mainly adjusted the air supply volume by monitoring the oxygen content of the flue gas at the furnace outlet to maintain the oxygen content at the desired value; monitored the boiler operating status by monitoring the pressure and flow rate of the fuel gas header and the furnace flame, and triggered corresponding interlock actions; automatically adjusted the fuel supply to increase or decrease the load by setting the steam demand; and controlled the makeup water flow rate by controlling the steam drum level. In addition to natural gas as the main fuel, POX syngas also accounts for a large proportion of the fuel gas, and its production depends on the stable output of upstream process units. When the upstream POX syngas supply is interrupted, or the POX unit gasifier trips, the POX syngas supply may decrease significantly in a short period of time, and the boiler side will not be able to make timely adjustments, thus affecting the normal operation of the boiler.

[0048] 2) Considering the safe operation of the boiler, the boiler system has a complete safety interlock logic. When the boiler triggers an unexpected interlock emergency stop due to its own reasons (such as low steam drum liquid level, feed water pump failure, induced draft fan failure, etc.), it will cause the fuel gas pipeline to pressurize rapidly and may cause a large amount of fuel gas to be released through the safety valve, thereby affecting safe production.

[0049] Figure 2 This is a flowchart illustrating the control method for switching fuels in a gas-fired boiler provided in an embodiment of the present invention. Please refer to it. Figure 2 The control method for switching fuels in a gas-fired boiler may include the following steps:

[0050] Step S110: Obtain the gas supply signal from the gas supply device, which is connected to the boiler dynamic operation system via a gas supply pipeline to supply gas to the boiler in the boiler dynamic operation system.

[0051] The preferred embodiments of the present invention can be as follows: Figure 3The fuel gas pipeline network model system, constructed based on the construction drawings of the on-site fuel gas pipeline of the gas-fired boiler, was tested. This model system can simulate the operation of the gas-fired boiler and control the switching of fuels. In this model system, corresponding variable acquisition and monitoring tags can be arranged according to actual flow, temperature, and pressure measurement points; corresponding pressure-flow characteristic equations can be constructed based on the flow characteristic parameters of the control valves. The inlet end of the main make-up gas pipeline (main make-up gas, for example, natural gas) can adopt a constant pressure mode. The flow rate of the main make-up gas pipeline is determined by the valve opening of the control valve, the flow velocity of the pipeline, and resistance characteristics. A dynamic boiler operation system (model) is constructed at the outlet end of the pipeline network. The constructed fuel gas pipeline network model system, control valves, and dynamic boiler operation system constitute a complete simulation model of boiler system control. This simulation model can also achieve bidirectional data interaction with the control model based on a virtual DCS. The execution of all control logic is consistent with the real DCS controller, and the I / O tags of the controller are mapped one-to-one with the variables of the simulation model. The simulation system is a development and testing platform that enables the simulation control strategy to be tested and optimized in real time, during acceleration and deceleration, and other operations.

[0052] The fuel distribution network model within the boundary area of ​​a single boiler in a dynamic boiler operation system is as follows: Figure 4 As shown, taking a three-main-fuel-pipe gas supply as an example, a single boiler may include a three-layer burner structure (there are 3*3 combustion furnaces). Each boiler also includes a ring gas supply pipe and 3*N (3*3) gas pipelines. Each gas pipeline is equipped with a flow monitoring point (e.g., FIC101, FIC102, etc.), and the ring gas supply pipe is equipped with a ring flow control valve (e.g., FV-1101, FV-1102, etc.).

[0053] Furthermore, the modeling of a single combustion furnace is as follows: Figure 5 As shown, a single combustion furnace may include: forced draft fan 1, air preheater 2, induced draft fan 3, recirculation fan 4, wind box 5, furnace 6, steam drum 7, economizer 8, and superheater 9, etc.

[0054] In such Figure 3-5 In the system model, necessary equipment parameters can be set for each component. These include pipe length, surface roughness, inner diameter, valve characteristics of control valves, valve flow coefficient Cv / Kv, number of elbows, number of reducers, inner diameter and length of the steam drum, combustion reaction parameters, and heat exchanger area. For calculating dynamic response characteristics, these equipment parameters can be set according to the actual equipment parameters.

[0055] The preferred embodiments of the present invention, by coupling dynamic modeling technology and virtual DCS control technology, can create a system such as... Figure 3-5The illustrated platform integrates a boiler fuel gas pipeline network, a boiler furnace with chemical reaction equilibrium, a boiler body system, a boiler control system, a variable mapping system, and a human-machine operation monitoring system into a unified testing and control strategy development platform. This invention can utilize the platform's accelerated computing capabilities to evaluate control strategies for switching fuels in different gas-fired boilers and optimize process control parameters.

[0056] After the above model is constructed, real-time data interaction can be achieved with the boiler system based on the virtual DCS virtual controller. The tag numbers required by the DCS virtual controller can be bound one-to-one with the dynamic model variables through a variable mapping system (e.g., temperature, pressure, flow rate, valve opening of control valves, etc.). Figure 6 As shown. Then, by comparing the operating parameters of the boiler dynamic operation system with those of the boiler system under normal operating conditions, the relevant parameters within the boiler dynamic operation system are gradually corrected to ensure that the dynamic response amplitude and trend of these parameters are close to those of the actual boiler system. This embodiment of the invention needs to study the characteristics of multiple components and multiple fuels, using real chemical components to simulate various fuels. Therefore, within the above model, changes in fuel composition can affect the thermal changes of chemical reactions in the furnace section of the combustion furnace, realistically reflecting the heat input to the steam drum based on parameters such as fuel composition, fuel flow rate, and air distribution, ultimately manifesting in changes in parameters such as steam drum temperature, pressure, and gas production.

[0057] Step S120: When the gas supply signal indicates that the gas supply device is abnormal, control the opening of the first set of control valves on the main gas supply pipeline to control the main gas supply pipeline to supply gas to the boiler in the boiler dynamic operation system.

[0058] Preferably, the gas supply device is a POX device, which includes at least two fuel production devices. When the gas supply signal indicates that the gas supply device is abnormal, controlling the opening of the first group of control valves includes: when the gas supply signal indicates that one of the fuel production devices of the POX device is abnormal, controlling the first main valve PV-2001B of the first group of control valves to an automatic control opening mode.

[0059] Please refer to Figure 3This example illustrates the control of fuel switching for gas-fired boilers using three 1000-ton-per-day SE coal-water slurry gasifiers in a POX unit area. Two of the three SE coal-water slurry gasifiers are in operation, with one on standby, and the operating pressure is, for example, 6.5 MPa. When the POX unit trips due to an abnormal fault, a gas supply signal indicating an abnormal gas supply to the POX unit (in this embodiment, the gas supply signal at this time is defined as a trip signal) is monitored. The syngas flow rate supplied by the POX unit drops rapidly to 0. At this time, it is necessary to quickly open the first set of control valves (e.g., pressure regulating valves) on the main make-up gas pipeline (e.g., the main natural gas pipeline) to replenish fuel in a timely manner. Since the pressure regulating valve is controlled by a PID control module in automatic mode, a conventional PID controller cannot open the valve in time, causing the boiler to shut down due to insufficient fuel.

[0060] In a preferred embodiment of the present invention, when the gas supply signal indicates that one of the fuel production devices of the POX unit is experiencing a gas supply malfunction, the first main valve PV-2001B of the first group of control valves is automatically controlled to open, and the first auxiliary valve PV-2001A does not participate in the fuel switching control.

[0061] Preferably, the step of controlling the opening of the first group of control valves when the gas supply signal indicates an abnormal gas supply to the gas supply device further includes: when the gas supply signal indicates an abnormal gas supply to the two fuel production units of the POX device, controlling the first auxiliary valve PV-2001A of the first group of control valves to a manual control opening mode; controlling the first main valve PV-2001B to a preset opening degree, and then controlling the first main valve PV-2001B to an automatic control opening mode; and determining the flow rate of the first auxiliary valve PV-2001A through the monitored flow rate of the boiler dynamic operation system. The flow feedforward prediction value of the main valve PV-2001B and the flow feedforward prediction value of the first auxiliary valve PV-2001A are used to obtain the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A; and the opening of the first main valve PV-2001B and the opening of the first auxiliary valve PV-2001A are adjusted accordingly based on the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A.

[0062] Please refer to Figure 3 and Figure 7 For example, when a trip signal is detected in both furnaces of the POX unit (i.e., the gas supply signal indicates that the gas supply to the two fuel production units of the POX unit is abnormal), the first auxiliary valve PV-2001A automatically switches to manual mode (automatic can be understood as the control valve automatically controlling the opening degree according to the flow rate, and manual can be understood as a fixed opening degree), and the first main valve PV-2001B is pre-opened and then put into automatic mode, with a pressure setting value of, for example, 0.42MPa.

[0063] Preferably, before controlling the first main valve PV-2001B to a preset opening degree, the control method for switching fuel in the gas-fired boiler further includes: when the gas supply signal indicates that the gas supply of the two fuel production devices of the POX unit is abnormal, acquiring the flow rate F1 shown by the first flow measurement point FIC001, the first flow measurement point FIC001 being arranged at the outlet pipe of the POX unit; calculating the flow rate F2 of the main gas supply pipe based on the flow rate F1; calculating the opening degree value V1 corresponding to the first main valve PV-2001B based on the flow rate F2 and the pressure-flow characteristic equation of the first main valve PV-2001B; and determining the preset opening degree by summing the difference V3 between the opening degree V1 and the current opening degree value V2 of the first main valve PV-2001B, after limiting the amplitude [5%, 20%], with the current opening value V2.

[0064] Continuing with the above example, when the POX unit's dual-furnace trip signal is detected, the real-time flow rate F1 of the POX unit boundary syngas flow meter FIC001, the main makeup gas flow rate F2 of the main makeup gas pipeline (in this embodiment, the main makeup gas is, for example, natural gas) converted from the calorific value of F1 flow rate, and then multiplied by F1 by X1, are used to obtain the corresponding opening value V1 through the pressure-flow characteristic equation of PV-2001B. This is then subtracted from the existing opening value V2, and the difference V3 is limited [5%, 20%], and summed with the current opening value V2 to obtain the preset opening value. Figure 7 In this context, X1 is, for example, 0.15.

[0065] Preferably, the step of determining the flow feedforward prediction value through the first main valve PV-2001B and the flow feedforward prediction value through the first auxiliary valve PV-2001A, and correspondingly obtaining the opening degree feedforward prediction value of the first main valve PV-2001B and the opening degree feedforward prediction value of the first auxiliary valve PV-2001A, includes: for the three-layer burner structure of each boiler in the boiler dynamic operation system, when the main supplementary gas ring flow control valve of each layer is open and the flow rate of the main supplementary gas ring supply pipeline is greater than a preset value, the flow rate value corresponding to the opening degree command of the main supplementary gas ring flow control valve is used as the flow feedforward prediction value of the corresponding layer. Each boiler includes a ring supply pipeline and 3*N gas pipelines, where N is the type of gas supplied. Each gas pipeline is equipped with a flow monitoring point, and the ring supply pipeline is equipped with... The flow control valve is used as follows: the sum of the flow feedforward prediction values ​​of each layer is used as the flow feedforward prediction value of the corresponding boiler; based on the sum Q of the flow feedforward prediction values ​​of each boiler, the correction coefficient X2, and the pressure-flow characteristic equation of the first auxiliary valve PV-2001A, the feedforward opening V4 of the first auxiliary valve PV-2001A is obtained, and the product of the feedforward opening V4 and the correction coefficient X3 is used as the opening feedforward prediction value of the first auxiliary valve PV-2001A; based on the sum Q of the flow feedforward prediction values ​​of each boiler model, the correction coefficient X2, and the pressure-flow characteristic equation of the first main valve PV-2001B, the feedforward opening V5 of the first main valve PV-2001B is obtained, and the product of the feedforward opening V5 and the correction coefficient X4 is used as the opening feedforward prediction value of the first main valve PV-2001B.

[0066] Please refer to Figure 4 and Figure 7 Following the example above, when the POX unit's dual-furnace trip signal is triggered, in order to synchronize the operation of the first set of control valves in the main make-up gas pipeline (natural gas main) and the main make-up gas (natural gas) collection loop flow control valve in front of the furnace, both the first main valve PV-2001B and the first auxiliary valve PV-2001A are equipped with feedforward. Please refer to... Figure 4 Taking a three-layer natural gas manifold flow control valve as an example, the opening command of the three-layer natural gas manifold flow control valve is used as the sum of the flow rates corresponding to its flow characteristics, which is also used as the flow feedforward output Q1 for natural gas demand. Only when the main gas supply (natural gas) manifold flow control valve of each layer releases its regulation and the flow rate is greater than or equal to (≥) the preset value F0 (unit: Nm3 / h), is the flow rate corresponding to the opening command of that layer's main gas supply (natural gas) flow control valve used as the flow feedforward prediction value for the first group of control valves; otherwise, it is set to 0. Please refer to [reference needed]. Figure 4 and Figure 7For the upper-level natural gas burner loop, if the flow rate through FIC101 is greater than or equal to the preset value F0, then the flow rate F11 to the upper-level natural gas burner loop is equal to the flow rate through FIC101; otherwise, the flow rate F11 = 0. The calculation methods for the flow rates F12 to the middle-level natural gas burner loop and F13 to the lower-level natural gas burner loop are similar. Figure 7 (Shown omitted). The feedforward output of the main gas supply (natural gas) demand is Q1 = F11 + F12 + F13. Taking a boiler dynamic operation system including 4 boilers as an example, the feedforward prediction value of natural gas demand flow is Q = (Q1 + Q2 + Q3 + Q4). After multiplying the natural gas demand flow feedforward prediction value Q by the correction coefficient X2, the feedforward opening degree V5 of the first main valve PV-2001B is obtained through the pressure-flow characteristic equation of the first main valve PV-2001B. The product of the feedforward opening degree V5 and the correction coefficient X4 is used as the feedforward prediction value of the opening degree of the first main valve PV-2001B. After multiplying the natural gas demand flow feedforward prediction value Q by the correction coefficient X2, the feedforward opening degree V4 of the first auxiliary valve PV-2001A is obtained through the pressure-flow characteristic equation of the first auxiliary valve PV-2001A. The product of the feedforward opening degree V4 and the correction coefficient X3 is used as the feedforward prediction value of the opening degree of the first auxiliary valve PV-2001A. Among them, the preset value F0 is, for example, 600, the correction coefficient X1 is, for example, 0.15, the correction coefficient X2 is, for example, 0.5, the correction coefficient X3 is, for example, 0.5, and the correction coefficient X4 is, for example, 0.6.

[0067] Please refer to Figure 3 Further preferably, when the gas supply signal indicates an abnormal gas supply to the two fuel production units of the POX device, the control method for switching fuel in the gas boiler further includes controlling the opening of a second set of control valves. A second set of control valves and a first pressure measuring point PIC101 are installed at a preset position at the inlet end of the main gas supply pipeline. The second set of control valves includes a second main valve PV-1001 and a second auxiliary valve PV-1005. Controlling the opening of the second set of control valves includes: controlling the second auxiliary valve PV-1005 to an automatic control opening mode, or controlling the second main valve PV-1001 to an automatic control mode. The system operates in an opening mode. Based on the monitored flow rate through the first set of control valves, it determines the flow rate feedforward prediction value of the second main valve PV-1001 and the flow rate feedforward prediction value of the second auxiliary valve PV-1005, and correspondingly obtains the opening degree feedforward prediction value of the second main valve PV-1001 and the opening degree feedforward prediction value of the second auxiliary valve PV-1005. Based on the opening degree feedforward prediction value of the second main valve PV-1001 and the opening degree feedforward prediction value of the second auxiliary valve PV-1005, it adjusts the opening degree of the second main valve PV-1001 and the second auxiliary valve PV-1005 accordingly.

[0068] Please refer to Figure 8 For example, a second set of control valves is installed at a preset position at the inlet of the main gas supply pipeline. This second set can, for instance, regulate the pressure of the main natural gas pipeline (from 4.0 MPa to 1.0 MPa). During normal operation, one of the second main valve PV-1001 and the second auxiliary valve PV-1005 is set to automatic, with a set value of, for example, 0.95 MPa. When a trip signal is detected in both furnaces of the POX unit, the state of the second set of control valves remains unchanged. That is, both the second main valve PV-1001 and the second auxiliary valve PV-1005 can be used to automatically control the pressure of the main gas supply pipeline during POX unit switching.

[0069] Preferably, controlling the opening of the second set of control valves further includes: when the second main valve PV-1001 is not in automatic control opening mode, recording the initial opening value V0 of the second main valve PV-1001; calculating the flow rate F6 passing through the second main valve PV-1001 according to the initial opening value V0 and the pressure-flow characteristic equation of the second main valve PV-1001; obtaining the corresponding final opening value V12 passing through the second main valve PV-1001 according to the flow rate F7 and the pressure-flow characteristic equation of the second main valve PV-1001, wherein within a preset time, the flow rate F6 passing through the second main valve PV-1001 increases to the flow rate F7 at a preset rate; and controlling the second main valve PV-1001 from the initial opening value V0 to the final opening value V12 within the preset time.

[0070] Please refer to Figure 8 Continuing from the previous example, since the second auxiliary valve PV1005 is a bypass pipeline, its adjustment capacity is limited and cannot meet the requirements for natural gas switching when the POX unit trips. Therefore, when the POX unit's dual-furnace trip signal is triggered, if the second main valve PV-1001 is not in automatic mode, the initial valve position of the second main valve PV-1001, i.e., the initial opening value V0, is recorded. Based on the initial opening value V0 and the pressure-flow characteristic equation of the second main valve PV-1001, the corresponding flow rate F6 is calculated; then the flow rate F7 is calculated, for example, flow rate F7 = F6 + 15000 Nm3 / h; the flow rate F7 through the second main valve PV-1001 is controlled to increase linearly to the corresponding termination opening value V12 within, for example, at a rate of 500 Nm3 / hs, within, for example, 30 seconds according to its flow characteristics. After 30 seconds, the opening of the second main valve PV-1001 can be manually adjusted as needed to prevent the opening of the second auxiliary valve PV-1005 from becoming too large and losing its automatic adjustment capability.

[0071] Preferably, the step of determining the flow feedforward prediction value of the second main valve PV-1001 and the flow feedforward prediction value of the second auxiliary valve PV-1005, and correspondingly obtaining the opening feedforward prediction value of the second main valve PV-1001 and the opening feedforward prediction value of the second auxiliary valve PV-1005, includes: obtaining the opening value V7 of the first main valve PV-2001B and the opening value V6 of the first auxiliary valve PV-2001A; obtaining the flow rate F1 through the first main valve PV-2001B based on the opening value V7 and the pressure-flow characteristic equation of the first main valve PV-2001B; and obtaining the flow rate F1 through the first auxiliary valve PV-2001A based on the opening value V6 and the pressure-flow characteristic equation of the first auxiliary valve PV-2001A. The flow rate F2 of 1A; the sum of the flow rates F1 and F2 is taken as the total flow rate F3 through the first group of control valves; based on the total flow rate F3, the correction coefficient X5, and the pressure-flow characteristic equation of the second main valve PV-1001, the feedforward opening V8 of the second main valve PV-1001 is obtained, and the product of the feedforward opening V8 and the correction coefficient X7 is taken as the feedforward prediction value of the opening of the second main valve PV-1001; based on the total flow rate F3, the correction coefficient X6, and the pressure-flow characteristic equation of the second auxiliary valve PV-1005, the feedforward opening V9 of the second auxiliary valve PV-1005 is obtained, and the product of the feedforward opening V9 and the correction coefficient X8 is taken as the feedforward prediction value of the opening of the second auxiliary valve PV-1005.

[0072] Please refer to Figure 8 Continuing with the above example, taking the opening value V7 of the first main valve PV-2001B and the opening value V6 of the first auxiliary valve PV-2001A as examples, the corresponding flow rates are obtained according to their respective pressure-flow characteristic equations, and then added together to obtain the total flow rate F3; flow rate F4 = F3 * correction coefficient X5, flow rate F5 = F3 * correction coefficient X6; based on the pressure-flow characteristic equations of the second main valve PV-1001 and the second auxiliary valve PV-1005, the corresponding opening values ​​V8 and V9 are obtained respectively using flow rates F4 and F5. The opening value V10 = opening value V8 * correction coefficient X7 is used as the feedforward prediction value of the opening of the second main valve PV-1001, and the opening value V11 = opening value V9 * correction coefficient X8 is used as the feedforward prediction value of the opening of the second auxiliary valve PV-1005. Among them, the correction factor X5 is, for example, 0.5, the correction factor X6 is, for example, 0.4, the correction factor X7 is, for example, 0.6, and the correction factor X8 is, for example, 0.5.

[0073] Other controls related to combustion in a preferred embodiment of the present invention may include: since the above-mentioned control for switching fuel in a gas-fired boiler introduces feedforward control, the valve position output lag problem caused by the pure feedback mechanism of conventional PID control is avoided. Therefore, the air supply volume can also be pre-increased. For example, if the oxygen compensation result output is increased by, for example, 3%, the corresponding air volume will be increased by, for example, 10800 Nm3 / h. The increased air volume can decay to 0 within, for example, 120 seconds. The target oxygen setpoint is increased by, for example, 1.5, and the target excess air coefficient is calculated using the increased target oxygen value. Similarly, the target air volume is compensated in the cross-limiting process to achieve the purpose of pre-increasing the air supply volume. The increased oxygen of 1.5 decays to 0 within, for example, 600 seconds after the POX unit trip signal is reset. At the same time, in order to avoid the limitation of the inlet damper opening being too small during the rapid increase of air volume, the inlet dampers of the forced draft fan and induced draft fan can be pre-opened by, for example, 5%. Through oxygen compensation, the fuel and air ratio can be kept constant under rapid switching conditions. And through two-stage feedforward, the three-valve coupling control of the main supplementary gas (natural gas) responds actively.

[0074] Further preferred, through steps S110-S120 and as follows Figure 3 The complete simulation model of the boiler system control shown, along with the control model of the boiler system based on virtual DCS, allows for experimentation and continuous iterative optimization of the boiler's fuel switching control.

[0075] Using examples, a simulation model of five boiler units in a chemical plant's refining unit was created based on a complete boiler system control system. Figure 4 The simulation of various operating conditions of the gas-fired boiler in the power center is shown. Through repeated simulation tests of the boiler system control simulation model, the control scheme and parameters are continuously optimized, ultimately achieving a control scheme for complex combustion control of multiple main fuels and rapid switching within seconds. This control scheme successfully completed the test of switching the main gas to natural gas within 50 seconds of an emergency shutdown of a single POX unit gasifier on an actual device. The test results are as follows: Taking the gas-fired boiler (1#) as an example, when the POX unit trips, the syngas is immediately interrupted, and the calorific value of the syngas accounts for 60% of the load of boiler #1. The test shows that the control scheme can achieve coordinated control of multiple main fuels in the boiler and can automatically complete the rapid switching of main fuels with a switching time of less than 50 seconds. The boiler load fluctuation is less than 25%, and the main control loops such as boiler fuel, air, and negative pressure respond automatically, maintaining stable boiler operation.

[0076] Accordingly, the embodiments of the present invention can achieve complex combustion control and rapid switching of multiple main fuels, maintain stable boiler operation in the event of upstream gas anomalies, ensure stable production of downstream ethylene and other units, and greatly reduce unplanned shutdowns. This saves on material losses, equipment lifespan reduction, and excessive pollutant emissions caused by frequent start-ups and shutdowns, thereby bringing significant economic and social benefits.

[0077] This invention also provides a simulation model for boiler system control with a furnace containing the actual chemical composition and combustion reaction of the fuel. This simulation model includes a fuel gas pipeline network model system constructed based on the construction drawings of the fuel gas pipelines at the gas-fired boiler site. The dynamic response characteristics of the parameters within this simulation model closely match those of the actual device. By continuously iterating and optimizing the fuel switching scheme of the gas-fired boiler within the simulation model, and introducing the pressure-flow characteristic equation (or valve characteristic curve) of the control valve into the control scheme, flow rate and valve opening are predicted, achieving decoupled control and significantly improving the response speed of the gas control valves in the pipeline network. As shown above, actual measurements demonstrate that under extreme conditions where the POX unit's syngas, which accounts for 60% of the normal operating calorific value, is suddenly interrupted, the gas-fired boiler fuel can be automatically and rapidly switched within 50 seconds. The implementation of this control scheme effectively ensures the stable operation of the plant's boiler system, thereby promoting a stable steam supply for the entire plant and minimizing the impact of a sudden shutdown of the POX unit on other steam-using units.

[0078] Figure 9 This is a schematic diagram of the control system for switching fuels in a gas-fired boiler provided in an embodiment of the present invention. Please refer to it. Figure 9 The control system for switching fuels in a gas-fired boiler may include a gas supply device, a main gas supply pipeline 102, and a control device (not shown in the figure). The gas supply device is a POX device 101, which includes at least two fuel production devices. The POX device 101 is connected to the boiler dynamic operation system 103 via a pipeline to supply gas to the boiler in the boiler dynamic operation system 103. A first flow measurement point FIC001 is provided at the outlet pipeline of the POX device 101. The main gas supply pipeline 102 is connected to the boiler dynamic operation system 103 to supply gas to the boiler in the boiler dynamic operation system 102 when the gas supply of the POX device 101 is abnormal. A first set of control valves (not shown in the figure) is arranged on the main gas supply pipeline 102. The first set of control valves includes a first main valve PV-2001B and a first auxiliary valve PV-2001A. The control device is used to control the POX device 101 and / or the main gas supply pipeline 102 to supply gas to the boiler in the boiler dynamic operation system 103 according to the control method for switching fuels in a gas-fired boiler described in steps S110-S120.

[0079] As mentioned above, Figure 3The fuel gas pipeline network model system shown, constructed based on the construction drawings of the on-site fuel gas pipeline of the gas-fired boiler, is the construction of the control system for switching fuel in a gas-fired boiler provided by the embodiment of the present invention. The control method for switching fuel in a gas-fired boiler described in steps S110-S120 can be verified and optimized in the model system before being implemented in the control system for switching fuel in a gas-fired boiler according to the embodiment of the present invention.

[0080] Each boiler in the preferred embodiment of the present invention's dynamic boiler operation system 103 may include: a combustion chamber for chemical reactions, a radiation chamber, a steam drum, a flue gas convection heat exchanger, a superheater, an economizer, a fan, and a water supply system.

[0081] In a preferred embodiment of the present invention, each boiler of the boiler dynamic operation system 103 includes a three-layer burner structure. Each boiler also includes a ring gas supply pipeline and 3*N gas pipelines, where N is the type of gas supplied. Each gas pipeline is equipped with a flow monitoring point, and the ring gas supply pipeline is equipped with a ring flow control valve.

[0082] The fuel distribution network model within the boundary area of ​​a single boiler in the boiler dynamic operation system 103 is as follows: Figure 4 As shown. Taking a boiler with three main fuel pipelines as an example, a single boiler may include a three-layer burner structure (there are 3*3 combustion furnaces). Each boiler also includes a ring gas supply pipeline and 3*N (3*3) gas pipelines. Each gas pipeline is equipped with a flow monitoring point (e.g., FIC101, FIC102, etc.), and the ring gas supply pipeline is equipped with a ring flow control valve (e.g., FV-1101, FV-1102, etc.).

[0083] Preferably, a second set of control valves and a first pressure measuring point PIC101 are provided at a preset position at the inlet end of the main air supply pipeline 102. The second set of control valves includes a second main valve PV-1001 and a second auxiliary valve PV-1005. The main air supply pipeline 102 supplies air by constant pressure control. The air supply flow rate of the main air supply pipeline 102 is determined by the opening degree of the second set of control valves, the pipeline flow velocity, and the characteristics of the pipeline resistance.

[0084] Preferably, the control device is further configured to construct a corresponding pressure-flow characteristic equation based on the flow characteristic parameters of the first group of control valves and the second group of control valves.

[0085] Preferably, the control device is also used for bidirectional data interaction with the virtual DCS-based control model of the boiler dynamic operation system.

[0086] It should be noted that the technical details of the control system for switching fuels in a gas-fired boiler provided in the embodiments of the present invention are similar to the control method for switching fuels in a gas-fired boiler provided in steps S110-S120, and will not be repeated here.

[0087] like Figures 3-5 The simulation model of the boiler system control with a furnace showing the actual fuel chemical composition and combustion reaction is constructed according to the control system for switching fuels in a gas-fired boiler provided by the embodiments of the present invention. Therefore, the advantages of the embodiments of the present invention also include:

[0088] 1) By coupling dynamic modeling technology and virtual DCS control technology, it is possible to create... Figure 3-5 The platform shown integrates a boiler fuel gas pipeline network, a boiler furnace with chemical reaction equilibrium, a boiler body system, a boiler control system, a variable mapping system, and a human-machine operation monitoring system into a unified testing and control strategy development platform. This embodiment of the invention utilizes the platform's accelerated computing capabilities to evaluate control strategies for switching fuels in different gas-fired boilers and optimize process control parameters. As shown above, the deviation rate of relevant parameters is less than 10%, providing an online verification platform for subsequent boiler control optimization.

[0089] 2) Given that gas-fired boilers have a more defined fuel composition compared to coal-fired boilers, a boiler model with actual fuel component properties (such as...) was developed. Figure 4 and 5 As shown in the figure, the model calculation results have a high degree of matching with the field operation data;

[0090] 3) The above-mentioned integrated platform is used to simulate the control scheme for rapid switching of alternative fuels under the condition of upstream gas cut-off, which avoids the secondary dangers that may be caused by actual equipment testing and does not affect the normal operation of the equipment.

[0091] 4) Through decoupling control, the introduction of valve characteristic curves of control valves, multi-device linkage and pre-start and other complex control loops, automatic control and second-level switching of multi-component gas boilers can be realized;

[0092] 5) The simulation model was further improved by utilizing operating parameters, enhancing its dynamic response capability. Based on this, various abnormal operating condition tests and simulations were completed, and control schemes and parameters were optimized for different operating conditions. As shown above, an automatic control scheme for a multi-component complex gas-fired boiler supporting a million-ton ethylene plant can be completed, and the boiler system can achieve a 60% proportion of main gas switching function within seconds.

[0093] 6) By using the optimized control scheme and parameters, the configuration of the on-site DCS system can be upgraded, and the reliability of the improved control scheme for the boiler system can be verified through empirical studies, testing and validation.

[0094] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0096] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0097] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0098] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0099] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0100] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0101] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0102] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A control method for fuel switching of a gas-fired boiler, characterized by, The control method for fuel switching of a gas-fired boiler comprises: obtaining a gas supply signal of a gas supply device, the gas supply device being connected to a boiler dynamic operation system through a gas supply pipeline to supply gas to a boiler in the boiler dynamic operation system; and when the gas supply signal shows that the gas supply device abnormally supplies gas, controlling the opening degree of a first group of control valves on a main gas supplement pipeline to control the main gas supplement pipeline to supply gas to the boiler in the boiler dynamic operation system, wherein the gas supply device is a POX device including at least two fuel production equipment, and the control of the opening degree of the first group of control valves when the gas supply signal shows that the gas supply device abnormally supplies gas comprises: when the gas supply signal shows that one of the fuel production equipment of the POX device abnormally supplies gas, controlling a first main valve PV-2001B of the first group of control valves to be in an automatic control opening degree mode, wherein the control of the opening degree of the first group of control valves when the gas supply signal shows that the gas supply device abnormally supplies gas further comprises: when the gas supply signal shows that both of the fuel production equipment of the POX device abnormally supply gas, controlling a first auxiliary valve PV-2001A of the first group of control valves to be in a manual control opening degree mode; controlling the first main valve PV-2001B to a preset opening degree, and then controlling the first main valve PV-2001B to be in the automatic control opening degree mode; determining a flow feedforward prediction value through the first main valve PV-2001B and a flow feedforward prediction value through the first auxiliary valve PV-2001A according to a monitored flow value of the boiler dynamic operation system, and correspondingly obtaining an opening degree feedforward prediction value of the first main valve PV-2001B and an opening degree feedforward prediction value of the first auxiliary valve PV-2001A; and adjusting the opening degree of the first main valve PV-2001B and the opening degree of the first auxiliary valve PV-2001A according to the opening degree feedforward prediction value of the first main valve PV-2001B and the opening degree feedforward prediction value of the first auxiliary valve PV-2001A.

2. The control method for fuel switching of a gas boiler according to claim 1, characterized in that, Before the control of the first main valve PV-2001B to the preset opening degree, the control method for fuel switching of a gas-fired boiler further comprises: when the gas supply signal shows that both of the fuel production equipment of the POX device abnormally supply gas, obtaining a flow F1 shown by a first flow measuring point FIC001, the first flow measuring point FIC001 being arranged at an outlet pipeline of the POX device; calculating a flow F2 of the main gas supplement pipeline according to the flow F1; calculating an opening degree value V1 corresponding to the first main valve PV-2001B according to the flow F2 and a pressure-flow characteristic equation of the first main valve PV-2001B; and determining a sum of the opening degree value V1 and a current opening degree value V2 of the first main valve PV-2001B as the preset opening degree after limiting a difference V3 between the opening degree value V1 and the current opening degree value V2 within a range of [5%, 20%].

3. The control method for fuel switching of a gas boiler according to claim 1, characterized in that, The determination of the flow feedforward prediction value of the first main valve PV-2001B and the flow feedforward prediction value of the first auxiliary valve PV-2001A, and the corresponding determination of the opening feedforward prediction value of the first main valve PV-2001B and the opening feedforward prediction value of the first auxiliary valve PV-2001A, comprises: For the three-layer burner structure of each boiler of the boiler dynamic operation system, when the main air supply ring flow control valve of each layer is opened and the flow of the main air supply ring gas supply pipeline is greater than a preset value, the flow value corresponding to the opening instruction of the main air supply ring flow control valve is taken as the flow feedforward prediction value of the corresponding layer, Wherein, each boiler comprises a ring gas supply pipeline and 3*N gas pipelines, N is the number of gas supply types, and a flow monitoring point is arranged on each gas pipeline, and a ring flow control valve is arranged on the ring gas supply pipeline; The sum of the flow feedforward prediction values of each layer is taken as the flow feedforward prediction value of the corresponding boiler; According to the sum Q of the flow feedforward prediction values of each boiler model, the correction coefficient X2, and the pressure-flow characteristic equation of the first auxiliary valve PV-2001A, the feedforward opening V4 of the first auxiliary valve PV-2001A is obtained, and the product of the feedforward opening V4 and the correction coefficient X3 is taken as the opening feedforward prediction value of the first auxiliary valve PV-2001A; According to the sum Q of the flow feedforward prediction values of each boiler model, the correction coefficient X2, and the pressure-flow characteristic equation of the first main valve PV-2001B, the feedforward opening V5 of the first main valve PV-2001B is obtained, and the product of the feedforward opening V5 and the correction coefficient X4 is taken as the opening feedforward prediction value of the first main valve PV-2001B.

4. The control method for fuel switching of a gas boiler according to claim 1, characterized in that, When the gas supply signal shows that the two fuel production devices of the POX device have abnormal gas supply, the control method for switching fuel of the gas-fired boiler further comprises controlling the opening of a second group of control valves, a preset position of the inlet end of the main air supply pipeline is provided with a second group of control valves and a first pressure measuring point PIC101, the second group of control valves comprises a second main valve PV-1001 and a second auxiliary valve PV-1005, and the control of the opening of the second group of control valves comprises: Controlling the second auxiliary valve PV-1005 to be in an automatic control opening mode, or controlling the second main valve PV-1001 to be in an automatic control opening mode; According to the monitored flow value through the first group of control valves, the flow feedforward prediction value of the second main valve PV-1001 and the flow feedforward prediction value of the second auxiliary valve PV-1005 are determined, and the opening feedforward prediction value of the second main valve PV-1001 and the opening feedforward prediction value of the second auxiliary valve PV-1005 are correspondingly obtained; and According to the opening feedforward prediction value of the second main valve PV-1001 and the opening feedforward prediction value of the second auxiliary valve PV-1005, the opening of the second main valve PV-1001 and the opening of the second auxiliary valve PV-1005 are correspondingly adjusted.

5. The control method for fuel switching of a gas boiler according to claim 4, characterized in that, The control of the opening of the second group of control valves further comprises: When the second main valve PV-1001 is not in the automatic control opening mode, record the initial opening value V0 of the second main valve PV-1001; According to the initial opening value V0 and the pressure flow characteristic equation of the second main valve PV-1001, calculate the flow F6 corresponding to the second main valve PV-1001; According to the flow F7 and the pressure flow characteristic equation of the second main valve PV-1001, obtain the terminal opening value V12 corresponding to the second main valve PV-1001, wherein the flow F6 through the second main valve PV-1001 increases to the flow F7 at a preset speed within a preset time; and Control the second main valve PV-1001 from the initial opening value V0 to the terminal opening value V12 within the preset time.

6. The control method for fuel switching of a gas boiler according to claim 4, characterized in that, The determination of the flow feedforward prediction value of the second main valve PV-1001 and the flow feedforward prediction value of the second auxiliary valve PV-1005, and the corresponding obtaining of the opening feedforward prediction value of the second main valve PV-1001 and the opening feedforward prediction value of the second auxiliary valve PV-1005, comprises: Obtain the opening value V7 of the first main valve PV-2001B and the opening value V6 of the first auxiliary valve PV-2001A; According to the opening value V7 and the pressure flow characteristic equation of the first main valve PV-2001B, obtain the flow F1 through the first main valve PV-2001B, and according to the opening value V6 and the pressure flow characteristic equation of the first auxiliary valve PV-2001A, obtain the flow F2 through the first auxiliary valve PV-2001A; Take the sum of the flow F1 and the flow F2 as the total flow F3 through the first group of control valves; According to the total flow F3, the correction coefficient X5 and the pressure flow characteristic equation of the second main valve PV-1001, obtain the feedforward opening V8 of the second main valve PV-1001, and take the product of the feedforward opening V8 and the correction coefficient X7 as the opening feedforward prediction value of the second main valve PV-1001; According to the total flow F3, the correction coefficient X6 and the pressure flow characteristic equation of the second auxiliary valve PV-1005, obtain the feedforward opening V9 of the second auxiliary valve PV-1005, and take the product of the feedforward opening V9 and the correction coefficient X8 as the opening feedforward prediction value of the second auxiliary valve PV-1005.

7. A control system for fuel switching of a gas-fired boiler, characterized in that, The control system for switching fuel of a gas-fired boiler comprises a gas supply device, a main gas supplement pipeline and a control device, The gas supply device is a POX device, which comprises at least two fuel production equipment, The POX device is connected to a boiler dynamic operation system through a pipeline to supply gas to a boiler in the boiler dynamic operation system, and a first flow measuring point FIC001 is arranged at the outlet pipeline of the POX device, The main gas supplement pipeline is connected to the boiler dynamic operation system to supply gas to the boiler in the boiler dynamic operation system when the gas supply of the POX device is abnormal, and a first group of control valves is arranged on the main gas supplement pipeline, The first group of control valves comprises a first main valve PV-2001B and a first auxiliary valve PV-2001A, The control device is used for controlling the POX device and / or the main air supplement pipeline to supply air to the boilers in the boiler dynamic operation system according to the control method for switching fuel of a gas-fired boiler according to any one of claims 1-6.

8. The control system for fuel switching of a gas-fired boiler according to claim 7, characterized in that, Each boiler in the boiler dynamic operation system comprises a combustion chamber for chemical reaction, a radiation chamber, a steam drum, a flue gas convection heat exchanger, a superheater, an economizer, a fan and a water supply system.

9. The control system for fuel switching of a gas-fired boiler according to claim 8, characterized in that, Each boiler in the boiler dynamic operation system comprises a three-layer burner structure, Each boiler further comprises a ring air supply pipeline and 3*N gas pipelines, N is the number of air supply types, a flow monitoring point is arranged on each gas pipeline, and a ring flow control valve is arranged on the ring air supply pipeline.

10. The control system for fuel switching of a gas-fired boiler of claim 7, wherein, A second group of control valves and a first pressure measuring point PIC101 are arranged at a preset position of an inlet end of the main air supplement pipeline, The second group of control valves comprises a second main valve PV-1001 and a second auxiliary valve PV-1005, The main air supplement pipeline supplies air through constant pressure control, and the air supply flow of the main air supplement pipeline is determined by the opening degree of the second group of control valves, pipeline flow rate and pipeline resistance characteristics.

11. The control system for fuel switching of a gas-fired boiler according to claim 10, characterized in that, The control device is further used for constructing corresponding pressure flow characteristic equations according to flow characteristic parameters of the first group of control valves and the second group of control valves.

12. The control system for fuel switching of a gas-fired boiler according to claim 7, characterized in that, The control device is further used for bidirectional data interaction with a control model based on virtual DCS of the boiler dynamic operation system.

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