A low-power intelligent controller and control method for a steam double boiler

Abstract

This invention belongs to the field of boiler steam control and discloses a low-power intelligent controller and control method for dual-boiler steam systems. The method comprises: S1, real-time detection of the temperatures of the preheating boiler and the high-temperature boiler using temperature sensors; S2, performing closed-loop control calculations on the preheating boiler and the high-temperature boiler based on the set steam temperatures to obtain their respective heating power requirements. This low-power intelligent controller and control method for dual-boiler steam systems addresses the problems of uncoordinated control, excessive total power, and significant impact from simultaneous startup that often occur in dual-boiler steam generation systems under limited total power conditions. It enables coordinated operation of the two boilers within the maximum permissible total power range, thus balancing the heating control accuracy, overall power constraints, and timing coordination during execution of the dual-boiler steam system.

Description

Technical Field

[0001] This invention relates to the technical field of instantaneous steam control methods for dual boilers, specifically to a low-power intelligent controller and control method for dual steam boilers. Background Technology

[0002] Stable high-temperature steam is required in fields such as coffee machines, high-temperature steam cleaning, and ironing. In order to generate instant steam, the overall power of the heating boiler is relatively large. If the control method and power distribution of the dual boilers are not effectively controlled, the large inrush current will affect the stability of the normal power supply and interfere with the surrounding equipment.

[0003] For example, a dual-boiler fully automatic coffee machine disclosed in the prior art (CN115251709A) includes a housing. The upper part of the housing contains a bean hopper. Inside the housing are a grinding system, a cheese frother, a brewing system, and a water circuit assembly. The outer side of the housing has a touch screen display and a coffee outlet. The grinding system is located below the bean hopper. The brewing system has a mechanism to drive its rotation. The water circuit assembly includes a water inlet pipe connected to a water pump. The water pump is connected to a three-way valve A via a pipe. The three-way valve A is connected to the cheese frother via a pipe. The three-way valve A is also connected to a preheating boiler via a pipe. The cheese frother is connected to the preheating boiler via a pipe. The preheating boiler is connected to a brewing boiler via a pipe. The brewing boiler is connected to the brewing system via a pipe. The brewing system is connected to the coffee outlet via a pipe. By preheating the milk and water in the preheating boiler, there is no need to wait when brewing coffee, shortening the heating time.

[0004] This document discloses the series connection structure of the preheating boiler and the brewing boiler (second boiler) in the water circuit assembly, which uses the preheating boiler to preheat the fluid to shorten the heating time.

[0005] For example, the publication number WO2009000039A1, "A DUAL HEATER APPLIANCE SUCH AS ACOFFEE MACHINE" (a dual heater device, such as a coffee machine), discloses that in appliances such as coffee machines, the controller distributes limited available power between two heating blocks (e.g., a coffee heating block and a steam heating block), which can be distributed in a ratio such as 40% / 60% or switched between the two heating blocks by duty cycle to achieve power sharing, and adjusts the power based on temperature sensors and operating modes.

[0006] While existing technologies disclose the series structure of preheating boilers and subsequent heating boilers, or the power distribution method among multiple heating units, none of them disclose a coordinated control scheme suitable for dual-boiler steam generation systems. In particular, they do not disclose the technical means to calculate the heating power demand, allocate power, and coordinate the start-up timing control of the preheating boiler and the high-temperature boiler separately under the condition of limited total heating power. This can easily lead to problems such as uncoordinated control of the two boilers or simultaneous start-up. Summary of the Invention

[0007] The purpose of this invention is to provide a low-power intelligent controller and control method for dual steam boilers to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a low-power intelligent control method for dual steam boilers, the control method comprising the following steps:

[0009] S1. The temperature of the preheating boiler and the temperature of the high-temperature boiler are detected in real time by a temperature sensor;

[0010] S2. Based on the set steam temperature, perform closed-loop control calculations on the preheating boiler and the high-temperature boiler respectively to obtain their respective heating power requirements;

[0011] S3. Calculate the sum of the heating power requirements of the preheating boiler and the high-temperature boiler. When the sum of the heating power requirements exceeds the preset total heating power limit, allocate the heating power of the preheating boiler and the high-temperature boiler through a power optimization allocation mechanism so that the total heating power after allocation does not exceed the total heating power limit.

[0012] S4. Based on the allocated heating power, configure the corresponding power control mode for the preheating boiler and the high-temperature boiler respectively and execute heating;

[0013] S5. During the heating process, the heating start-up sequence of the preheating boiler and the high-temperature boiler is optimized and controlled to avoid both starting heating simultaneously.

[0014] Furthermore, the closed-loop control calculation in S2 is PID control, specifically, based on the temperature difference between the target temperature and the actual temperature of the preheating boiler and the high-temperature boiler, PID calculations are performed to obtain the corresponding heating power requirements.

[0015] Furthermore, the maximum allowable total power is a pre-set maximum allowable total power for the two boilers, used to limit the real-time total heating power of the preheating boiler and the high-temperature boiler. The maximum allowable total power is 3kW, and through the optimized allocation in S3, the real-time total heating power of the two boilers is controlled within 3kW.

[0016] Furthermore, the power supply system is 220VAC / 50Hz or 120VAC / 60Hz, and one sine wave cycle is defined as one electrical cycle.

[0017] Furthermore, the power control method in S4 adopts a zero-crossing start-up method and a cycle control method. By controlling the number of electrical cycles conducted in each control cycle, different heating power levels can be achieved.

[0018] Furthermore, in the aforementioned frequency control method, the maximum control cycle is 10 electrical cycles, and the power control timing is configured according to the corresponding frequency of the preheating boiler and the high-temperature boiler.

[0019] Furthermore, the optimized control in S5 includes: configuring the turn-on timing of the preheating boiler and the high-temperature boiler in a staggered manner according to the final output power allocated to them, so as to avoid the two boilers starting heating simultaneously in the same electrical cycle.

[0020] Furthermore, the steam generation system adopts a two-stage structure, where cold water first enters the preheating boiler for preheating, and then enters the high-temperature boiler for vaporization, in order to avoid the sudden drop in temperature and pressure fluctuation caused by cold water directly entering the high-temperature boiler.

[0021] Furthermore, when the power supply system is 120VAC and the maximum allowable total power is 3000W, the maximum operating current of the dual boiler steam generation system during operation is 25A.

[0022] A low-power intelligent controller for dual steam boilers is used to run the S1-S5 method steps.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The low-power intelligent controller and control method for dual-boiler steam systems address the problems of uncoordinated control of the two boilers, excessive total power, and large impact from simultaneous start-up that easily occur when the total power of the dual-boiler steam generation system is limited. By performing temperature detection, power demand calculation, power allocation under total power constraints, frequency band power control, and start-up timing optimization on the preheating boiler and the high-temperature boiler respectively, the dual boilers can achieve coordinated operation within the maximum allowable total power range. This balances the heating control accuracy, overall power constraint requirements, and timing coordination during the execution process of the dual-boiler steam system, as detailed below.

[0024] 1. Improve the targeting and coordination of dual-boiler control.

[0025] This application performs temperature detection and PID closed-loop control calculations on the preheating boiler and the high-temperature boiler respectively, and obtains the heating power requirements of the two boilers respectively. This can more accurately reflect the different thermal states and heating requirements of the two boilers, avoid treating the two boilers as a single object for coarse control, and thus improve the pertinence and coordination of the heating control of the two boilers.

[0026] 2. Avoid exceeding total power limits and improve the feasibility of power control.

[0027] After obtaining the target output power of each of the two boilers, this application further calculates the total target output power of the two boilers and limits the distribution of the output power of the two boilers when the maximum allowable total power is exceeded, so that the real-time total heating power of the two boilers does not exceed the preset upper limit. At the same time, through zero-crossing start and frequency control, the distributed output power is implemented as a specific conduction control sequence, thereby satisfying the overall power supply constraints and improving the feasibility of the dual boiler power control scheme.

[0028] 3. Reducing the simultaneous start-up of two boilers helps maintain stable operation.

[0029] Based on power distribution and power control, this application further optimizes the start-up sequence of the two boilers, so that the start-up heating cycle of the high-temperature boiler is allocated within the electrical cycle of the preheating boiler stopping heating, thus avoiding the simultaneous start-up of the two boilers in the same electrical cycle. Combined with the two-stage structure of cold water preheating first and then vaporizing, it helps to reduce temperature fluctuations and start-up shocks caused by the lack of coordination in the control of the two boilers, and improves the stability of the steam generation process of the two boilers. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the dual-boiler heating system of the present invention;

[0031] Figure 2 This is a schematic diagram of the dual-boiler steam control process of the present invention;

[0032] Figure 3 This is a schematic diagram of different heating power control methods of the present invention;

[0033] Figure 4 This is a schematic diagram of the boiler heating start-up sequence of the present invention;

[0034] Figure 5 This is a schematic diagram of the power distribution and limiting control process for dual boilers according to the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see Figures 1-5 The present invention provides the following technical solution:

[0037] A low-power intelligent controller and control method for dual steam boilers are disclosed. The controller is used to run the following steps, wherein the steam generation system adopts a two-stage structure. Cold water first enters the preheating boiler for preheating, and then enters the high-temperature boiler for vaporization, and finally sprays out from the steam outlet. This avoids the sudden drop in temperature and pressure fluctuation caused by cold water directly entering the high-temperature boiler. The dual-boiler steam generation system is powered by mains electricity, which can be 220VAC / 50Hz or 120VAC / 60Hz. One sine wave cycle is defined as one electrical cycle. The dual-boiler steam generation system includes two heating modules corresponding to the preheating boiler and the high-temperature boiler, respectively. Through subsequent power distribution, power control and start-up timing optimization, the coordinated operation of the two boilers is achieved under the condition of limited total heating power.

[0038] In this embodiment, the preheating boiler is mainly used to preheat the liquid entering the system, and the high-temperature boiler is mainly used to further heat the preheated liquid to a vaporized state and form steam output. By performing temperature detection, power demand calculation, power allocation under total power constraints, and start-up timing coordination control on the preheating boiler and the high-temperature boiler respectively, the coordinated heating of the two boilers can be achieved without the total heating power exceeding the preset upper limit. The following describes this embodiment in detail with reference to steps S1 to S5.

[0039] S1. The temperature of the preheating boiler and the high-temperature boiler are detected in real time by temperature sensors. Specifically, a first temperature sensor (NTC1) is installed on the preheating boiler to detect the temperature of the preheating boiler, and a second temperature sensor (NTC2) is installed on the high-temperature boiler to detect the temperature of the high-temperature boiler. The control system collects the actual temperature data of the preheating boiler and the high-temperature boiler through the first and second temperature sensors respectively to obtain the actual temperature of the preheating boiler and the high-temperature boiler, providing temperature input signals for subsequent closed-loop control calculations. In conjunction with the dual-boiler steam generation system of this application, the dual-boiler steam generation system consists of a water tank, a feed water pump, a preheating boiler, a high-temperature boiler, and a steam outlet. After being transported by the water tank and the feed water pump, cold water first enters the preheating boiler for preheating, and then enters the high-temperature boiler for further heating and vaporization. During this process, the control system detects the temperature status of the preheating boiler and the high-temperature boiler in real time.

[0040] The operating principle of this step is that this application adopts a dual-boiler, two-stage heating structure. The preheating boiler mainly undertakes the initial heating function, while the high-temperature boiler mainly undertakes the subsequent vaporization function. Therefore, the thermal states of the two boilers are not the same during operation. If only a single temperature detection is performed on the entire system, it is difficult to accurately reflect the actual heating demand of each boiler. By separately detecting the actual temperatures of the preheating boiler and the high-temperature boiler, basic data can be provided for subsequent PID closed-loop control of the two boilers. This allows the control system to independently calculate the corresponding heating power demand for each boiler based on its temperature deviation, thus providing a prerequisite for subsequent total power limitation, power allocation, and control timing optimization. In this application, the control system can adjust the heating power demand based on the ironing process. The target temperature Ti of the inlet boiler and the target temperature To of the outlet boiler are set in either the mode or the steam working mode. The actual internal temperature Ti of the inlet boiler and the actual internal temperature To of the outlet boiler are sampled in real time. The inlet boiler corresponds to the preheating boiler in this application, and the outlet boiler corresponds to the high-temperature boiler in this application. In an optional embodiment, the first temperature sensor and the second temperature sensor can be respectively set on the inner wall, outer wall, or thermally connected position of the preheating boiler and the high-temperature boiler to continuously output temperature signals characterizing the thermal state of the corresponding boiler. The controller reads the two temperature signals according to a preset sampling period and uses them as the basic input for temperature difference calculation and PID operation in step S2.

[0041] S2. Based on the set steam temperature, closed-loop control calculations are performed on the preheating boiler and the high-temperature boiler to obtain their respective heating power requirements. The closed-loop control calculation in step S2 is PID control. Specifically, based on the temperature difference between the target temperature and the actual temperature of the preheating boiler and the high-temperature boiler, PID calculations are performed to obtain the corresponding heating power requirements. Specifically, the equipment sets the target temperature Ti of the preheating boiler and the target temperature To of the high-temperature boiler according to the needs of the steam working mode or ironing mode. Based on the actual temperature Ti of the preheating boiler and the actual temperature To of the high-temperature boiler collected in step S1, the main controller calculates the temperature difference ΔTi of the preheating boiler and the temperature difference ΔTo of the high-temperature boiler, respectively. Based on the pre-tuned PID parameters Kpi, Kii, Kdi of the preheating boiler and the PID parameters Kpo, Kio, Kdo of the high-temperature boiler, the corresponding power adjustment changes ΔPi and ΔPo of the two boilers are calculated respectively. Among them, Pi and Po represent the target power that the preheating boiler and the high-temperature boiler need to output now, respectively, and Pi′ and Po′ represent the original output power of the preheating boiler and the high-temperature boiler before PID calculation, respectively. According to the PID calculation control, the following can be obtained:

[0042] ΔPi(k)=Kpi[△Ti(k)-△Ti(k-1)]+Kii△Ti(k)+Kdi[△Ti(k)-2△Ti(k-1)+△Ti(k-2)];

[0043] ΔPo(k)=Kpo[△To(k)-△To(k-1)]+Kio△To(k)+Kdo[△To(k)-2△To(k-1)+△To(k-2)];

[0044] The target output power of the preheating boiler and the high-temperature boiler were further obtained as follows:

[0045] Pi=Pi′+ΔPi; Po=Po′+ΔPo.

[0046] The operating principle of this step is that this application does not treat the two boilers as a single heating object for unified control, but rather treats the preheating boiler and the high-temperature boiler as two controlled objects and performs closed-loop regulation separately. Since the preheating boiler mainly undertakes the pre-stage heating of the inlet water, and the high-temperature boiler mainly undertakes the post-stage high-temperature vaporization, they differ in thermal inertia, heating rate, and corresponding steam formation. Therefore, by calculating the temperature difference separately and executing PID calculations separately, the real-time heating needs of each boiler can be more accurately reflected. Through this method, the control system can increase the power demand of the preheating boiler when the temperature difference is large, and increase the power demand of the high-temperature boiler when the temperature difference is large, thereby forming independent target power output results P for each of the two boilers. i and Po provide the basis for the total power limit, optimized allocation, and subsequent power control in step S3. The Pi and Po obtained in this step belong to the target output power of each boiler before the maximum allowable total power limit of the two boilers is applied. Further allocation and adjustment need to be combined with the total power constraint. In one optional embodiment, the controller repeatedly executes the above PID calculation according to a fixed control cycle, so that the preheating boiler and the high-temperature boiler can update their respective target power requirements according to the latest sampled temperature in each control cycle. In another optional embodiment, Pi′ and Po′ can take the actual execution power output to the preheating boiler and the high-temperature boiler in the previous control cycle, so that the power adjustment in the current cycle is continuously corrected based on the output result of the previous cycle.

[0047] S3. Calculate the sum of the heating power requirements of the preheating boiler and the high-temperature boiler. When the sum of the heating power requirements exceeds the preset maximum allowable total power, optimize the allocation of the heating power of the two boilers according to the actual temperature state of the preheating boiler and the high-temperature boiler, so that the real-time total heating power of the two boilers after allocation does not exceed the maximum allowable total power. The maximum allowable total power is the preset maximum allowable total power of the two boilers, which is used to limit the real-time total heating power of the preheating boiler and the high-temperature boiler. In one embodiment, the maximum allowable total power is 3kW, and through the optimization allocation in step S3, the real-time total heating power of the two boilers is controlled within 3kW. Specifically, after obtaining the target output power Pi and Po of the preheating boiler and the high-temperature boiler respectively in step S2, the control system further calculates the total target output power Prt of the two boilers, where: Prt=Pi+Po;

[0048] The system pre-sets the maximum allowable total power Pok for the two boilers. When the total target output power Prat is less than or equal to the maximum allowable total power Pok, the control system maintains the preheating boiler and the high-temperature boiler according to their respective target output powers Pi and Po for subsequent control. When the total target output power Prat is greater than the maximum allowable total power Pok, the control system limits the output power of the preheating boiler and the high-temperature boiler to obtain the adjusted final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler, such that: Pri + Pro ≤ Pok.

[0049] In one implementation, the maximum allowable total power Pok is set to 3000W, and the rated power of the preheating boiler and the high-temperature boiler can be set to 2500W respectively, so the rated total power of the two boilers is 5000W. The actual operation of the two boilers is constrained by the maximum allowable total power Pok for output control. In an optional implementation, when Prt does not exceed Pok, Pri = Pi and Pro = Po can be taken; when Prt exceeds Pok, the control system compresses or adjusts Pi and Po according to the preset power distribution rules to obtain the final output power Pri and Pro that satisfy Pri + Pro ≤ Pok.

[0050] The operating principle of this step is that Pi and Po obtained in step S2 reflect the independent power demands proposed by the preheating boiler and the high-temperature boiler based on their own temperature deviations. However, the dual-boiler system is limited by the overall power supply capacity and safety requirements in actual operation. Therefore, the target power of the two boilers cannot be simply superimposed. When the preheating boiler and the high-temperature boiler are simultaneously under a large temperature difference, Pi and Po may be high at the same time. If Pi and Po are directly output, the total heating power of the two boilers may easily exceed the maximum allowable power supply capacity of the equipment. Therefore, after the independent PID calculation of the two boilers, this step further sets up a total power limit and power allocation link. First, the total target output power Prt of the two boilers is calculated, and then it is compared with the maximum allowable total power Pok. When the limit is exceeded, the final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler are re-determined. In this way, while retaining the separate closed-loop control of the two boilers, the total power actually executed by the two boilers can be controlled. The power is always within the allowable range, thus avoiding the situation where the total power of the two boilers runs out of control or exceeds the limit during the heating process. For the dual-boiler steam generation system of this application, the preheating boiler is used for the front-stage heating and the high-temperature boiler is used for the rear-stage vaporization. Although both have independent heating requirements, they still need to comply with the total power constraint of the whole machine. Therefore, by setting the limiting relationship between Pri, Pro, Prt and Pok, the basis for coordinated control of the two boilers under the condition of limited total power can be established. In one optional embodiment, in addition to considering Pi and Po, Pri and Pro can be further determined by comprehensively considering the current temperature status of the preheating boiler and the high-temperature boiler, the output status of the previous control cycle, or the preset priority. In another optional embodiment, the priority rules, over-limit compression rules, and power allocation algorithm of the preheating boiler and the high-temperature boiler can be set according to different product models or different steam modes so as to achieve coordinated output of the two boilers under the premise of meeting the total power constraint.

[0051] S4. Based on the allocated heating power, configure the corresponding power control mode for the preheating boiler and the high-temperature boiler respectively and execute heating; the power control mode in step S4 adopts the zero-crossing start mode and the pass-through control mode. By controlling the number of electrical cycles conducted in each control cycle, different levels of heating power are achieved; in the pass-through control mode, the maximum control cycle is 10 electrical cycles, and the power control timing is configured according to the corresponding pass-through number of the preheating boiler and the high-temperature boiler. Specifically, the dual boiler steam generation system is powered by the mains power supply, which can be 220VAC / 50Hz or 120VAC / 60Hz, and one sine wave cycle is defined as one electrical cycle;

[0052] Figure 3In the diagram, Ntotal represents the total number of control electrical cycles within a control cycle, Non represents the number of conduction electrical cycles within that control cycle, and the remaining Ntotal-Non electrical cycles are heating-off cycles. The sine wave segment in the diagram represents the corresponding boiler conducting heating within that electrical cycle, and the horizontal line segment represents the corresponding boiler stopping heating within that electrical cycle. The average output power of a boiler within a control cycle corresponds to the ratio of the number of conduction electrical cycles (Non) to the total number of control electrical cycles (Ntotal). Figure 3 The power supply waveforms at 100%, 50%, 33%, 10%, and 0% power levels are shown. At 100% power, conduction occurs in all electrical cycles; at 50% power, conduction and off-circuiting alternate in a 1:1 ratio; at 33% power, conduction occurs in one electrical cycle out of every three; at 10% power, conduction occurs in one electrical cycle out of every ten; and at 0% power, conduction is off in all electrical cycles. This applies to preheating boilers and high-temperature boilers. Figure 3 The number of conduction electrical cycles Non in S4 can correspond to the number of waves Ni and No in S4, respectively, and the maximum value of the control cycle is preferably 10 electrical cycles.

[0053] After obtaining the final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler in step S3, the control system converts the final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler into corresponding frequency control parameters. The frequency of the preheating boiler is denoted as Ni, and the frequency of the steam boiler is denoted as No. Both Ni and No are integer variables. The control system uses a maximum control cycle of 10 electrical cycles as a benchmark. Within each control cycle, it adjusts the output power of the preheating boiler and the high-temperature boiler by controlling the number of electrical cycles during which the preheating boiler and the high-temperature boiler are turned on. When the boiler is at a higher power level, the corresponding number of electrical cycles during which the boiler is turned on within one control cycle... More; when the boiler is at a lower power level, the number of electrical cycles that the corresponding boiler conducts within a control cycle is less, so that the two boilers can perform heating according to the final output power allocated in step S3. In an optional embodiment, when a boiler is in full power output state, it can conduct heating in each electrical cycle; when a boiler is in non-full power output state, it conducts according to the preset number of waves in a maximum control cycle, and stops heating in the remaining electrical cycles. In a further optional embodiment, Ni and No can be calculated according to the proportional relationship between Pri and Pro and their respective rated power, so that the average output power of the preheating boiler and the high-temperature boiler corresponds to the allocated final output power respectively.

[0054] The operating principle of this step is that Pri and Pro obtained in step S3 still belong to the target power that each of the two boilers should execute. However, under AC power supply conditions, the boiler heating module needs to be converted into an actual executable heating action through a specific timing control method. This application adopts a zero-crossing start-up method, so that the boiler starts conducting heating at the zero-crossing point of AC power, thereby reducing the impact at the moment of start-up. At the same time, a cycle control method is adopted to control the boiler to turn on and off in units of a complete electrical cycle. By configuring different numbers of conducting electrical cycles within a maximum control cycle, the average output power control of the two boilers at different levels is realized. For the preheating boiler and the high-temperature boiler, the control system does not adjust the power by continuously simulating voltage regulation, but by discretely distributing the complete electrical cycle, so that the heating module turns on within a predetermined number of electrical cycles and stops in the remaining electrical cycles, thereby obtaining the power corresponding to Pri and Pro. The corresponding average heating power, this control method can reduce EMI radiation interference and harmonic current while realizing power regulation, and provide a unified cycle allocation basis for staggered start and timing optimization in subsequent step S5. Since the final output power of the two boilers has been limited by the maximum allowable total power Pok in step S3, after configuring the pass frequency sequence with Ni and No in step S4, the final output power of the two boilers can be implemented in the actual electrical cycle control sequence. In one optional embodiment, the control system can pre-establish a correspondence table between power level and pass frequency, and directly look up Ni and No after determining Pri and Pro. In another optional embodiment, the control system can also dynamically determine Ni and No according to the target output power of the preheating boiler and high temperature boiler in the current control cycle in a real-time calculation manner, so as to realize the real-time adjustment of the power control mode of the two boilers.

[0055] After the control system completes the final output power allocation between the preheating boiler and the high-temperature boiler in S3, it determines the number of passes Ni corresponding to the preheating boiler and the number of passes No corresponding to the high-temperature boiler based on the allocated final output power, and performs lookup control according to the preset correspondence between the number of passes and the conduction timing. Specifically, when Ni or No is 0, the corresponding boiler is shut down; when Ni or No is 1, one boiler is turned on every 10 electrical cycles, and 10 electrical cycles constitute one control cycle; when Ni or No is 2, one boiler is turned on every 5 electrical cycles, and 5 electrical cycles constitute one control cycle; when Ni or No is 3, one boiler is turned on every 3 electrical cycles, and 3 electrical cycles constitute one control cycle; when Ni or No is 4, a combination of "one boiler turned on every 3 electrical cycles" and "one boiler turned on every 2 electrical cycles" is used, and 5 electrical cycles constitute one control cycle; when Ni or No is 5, one boiler is turned on every 2 electrical cycles, and 2 electrical cycles constitute one control cycle; when Ni or When No is 6, a combination of "two boilers conducting every three electrical cycles" and "one boiler conducting every two electrical cycles" is used, with five electrical cycles constituting one control cycle. When Ni or No is 7, a combination of two sets of "three boilers conducting every four electrical cycles" and one set of "one boiler conducting every two electrical cycles" is used, with ten electrical cycles constituting one control cycle. When Ni or No is 8, four boilers are conducting every five electrical cycles, with five electrical cycles constituting one control cycle. When Ni or No is 9, nine boilers are conducting every ten electrical cycles, with ten electrical cycles constituting one control cycle. When Ni or No is 10, all electrical cycles are conducted, with one electrical cycle constituting one control cycle. After determining the conduction schemes for the preheating boiler and the high-temperature boiler, the control system enters the main logic control flow and, in conjunction with subsequent startup timing optimization control, coordinates the start time and sequence of the two boilers to avoid simultaneous startup and heating within the same electrical cycle.

[0056] S5. During the heating process, the heating start-up sequence of the two boilers is optimized based on their final output power to avoid simultaneous heating. The optimization control in step S5 includes: staggering the conduction sequence of the preheating boiler and the high-temperature boiler based on their allocated final output power to prevent simultaneous heating within the same electrical cycle. Specifically, after determining the wave pass numbers Ni and No for the preheating boiler and the high-temperature boiler in step S4, the control system further adjusts the conduction start time and sequence of the preheating boiler and the high-temperature boiler within a maximum control cycle, ensuring that the high-temperature boiler's heating start-up cycle is allocated to the electrical cycle during which the preheating boiler stops heating. This prevents both boilers from starting heating simultaneously within the same electrical cycle. In other words, the control... When constructing the cycle control sequence for the two boilers, the control system not only determines the number of electrical cycles that the preheating boiler and the high-temperature boiler need to conduct within a control cycle, but also further determines the distribution of these electrical cycles throughout the entire control cycle. This ensures that the start-up heating actions of the preheating boiler and the high-temperature boiler are staggered in time. In one optional embodiment, when both the preheating boiler and the high-temperature boiler are in a non-full-power output state, the control system prioritizes arranging the conduction cycle of the high-temperature boiler within the electrical cycle in which the preheating boiler stops heating. In another optional embodiment, when the preheating boiler is at 50% heating power and the high-temperature boiler is at 20% heating power, the control system adopts a staggered start-up method for the preheating boiler and the high-temperature boiler, so that the start-up electrical cycles of the two boilers are staggered to avoid simultaneous start-up within the same electrical cycle.

[0057] Furthermore, such as Figure 4 As shown, Figure 4 The staggered heating power supply waveforms of the preheating boiler and the high-temperature boiler are shown along the same time axis. The upper waveform represents the power supply waveform when the preheating boiler is heating at 50% power, and the lower waveform represents the power supply waveform when the high-temperature boiler is heating at 20% power. The sine wave segments in the figure represent the corresponding boiler's heating during that electrical cycle, and the horizontal line segments represent the corresponding boiler's heating stopping during that electrical cycle. The controller staggers the start time and cycle distribution of the two boilers' conduction within the same control cycle, prioritizing the high-temperature boiler's conduction electrical cycle within the preheating boiler's non-conducting electrical cycle, thereby preventing both from starting simultaneously within the same electrical cycle. Figure 4 Taking the operating condition shown as an example, within a control cycle containing 10 electrical cycles, the preheating boiler can be set to 5 conducting electrical cycles, the high-temperature boiler can be set to 2 conducting electrical cycles, and the 2 conducting electrical cycles of the high-temperature boiler can be distributed within the electrical cycles in which the preheating boiler is not conducting. In this way, while meeting the average output power requirements of the two boilers, the peak current of the system and the impact of simultaneous start-up are reduced.

[0058] The operating principle of this step is that although step S3 has limited the real-time total heating power of the two boilers, and step S4 has converted the final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler into corresponding frequency control sequences, if the two boilers start and conduct simultaneously within the same electrical cycle, instantaneous heating superposition may still occur at the execution level, thereby increasing the system startup impact and hindering the stable operation of the two boilers under the condition of limited total power. Therefore, after power allocation and power control, this application further optimizes the timing of the two boilers by staggering the start time and conduction cycle distribution of the two boilers, so that the high-temperature boiler and the preheating boiler are staggered in the time domain, thereby reducing the situation of the two boilers starting simultaneously. For the dual-boiler steam generation system of this application, the preheating boiler and the high-temperature boiler respectively undertake the functions of front-stage heating and rear-stage vaporization. Although both require Each boiler needs to complete its heating task within a certain time, but it is not required that they start heating simultaneously within the same electrical cycle. Therefore, through timing optimization, the actual execution process of the two boilers can be made more coordinated without changing the final output power requirements of the two boilers. This method works in conjunction with the total power limit in step S3 and the pass-through control in step S4 to form a coordinated control process for the two boilers under the condition of limited total power. In one optional embodiment, the control system can dynamically adjust the conduction sequence of the two boilers according to the pass-through number of the preheating boiler and the high-temperature boiler, the conduction end position of the previous control cycle, or the remaining allocable electrical cycles of the current control cycle. In another optional embodiment, the control system can pre-set several sets of staggered control templates suitable for different power combinations, and call the corresponding templates to generate the conduction timing sequence of the preheating boiler and the high-temperature boiler after determining Ni and No.

[0059] The overall operation process of this implementation method:

[0060] The dual-boiler steam control method of this embodiment is applied to a dual-boiler steam generation system consisting of a water tank, a feedwater pump, a preheating boiler, a high-temperature boiler, and a steam outlet. During system operation, the liquid in the water tank, under the action of the feedwater pump, first enters the preheating boiler for initial heating, then enters the high-temperature boiler for further heating and vaporization, and finally outputs steam from the steam outlet. The control system first detects the actual temperatures of the preheating boiler and the high-temperature boiler using temperature sensors in step S1. Then, in step S2, based on the temperature difference between the target temperature and the actual temperature of each boiler, PID control calculations are performed to obtain the target output power Pi of the preheating boiler and the target output power Po of the high-temperature boiler. Next, in step S3, the total target output power Prt of the dual boilers is calculated and compared with the preset maximum allowable total power Pok. When Prt does not exceed Pok, the dual boilers can proceed according to... Each boiler performs subsequent control according to its target output power. When Prt exceeds Pok, the output power of the preheating boiler and the high-temperature boiler is allocated and adjusted to obtain the final output power Pri of the preheating boiler and the final output power Pro of the high-temperature boiler, which satisfy Pri + Pro ≤ Pok. Then, in step S4, Pri and Pro are converted into corresponding pass-through control parameters Ni and No, and zero-crossing start and pass-through control are adopted. Based on 10 electrical cycles as the maximum control cycle, power control is performed on the preheating boiler and the high-temperature boiler respectively. Finally, in step S5, the conduction start time and conduction cycle distribution of the two boilers are optimized and adjusted according to the final output power of the preheating boiler and the high-temperature boiler and their corresponding pass-through number, so that the start heating cycle of the high-temperature boiler is allocated to the electrical cycle of the preheating boiler stopping heating, avoiding the simultaneous start heating of the two boilers in the same electrical cycle.

[0061] Through the above steps, this embodiment can form the following control process in a dual-boiler steam generation system: first, the temperature of the two boilers is detected separately and their power requirements are calculated independently; then, the final output power of the two boilers is limited and allocated under the constraint of the maximum allowable total power; then, the allocated output power is converted into the corresponding frequency control timing sequence; finally, the simultaneous start-up of the two boilers at the execution level is reduced by optimizing the start-up timing sequence. Thus, while maintaining the independent control capabilities of the preheating boiler and the high-temperature boiler, the dual-boiler system can also make the overall real-time output power subject to unified constraints and make the actual conduction control process more coordinated. In one embodiment, when the dual-boiler steam generation system uses 120VAC power supply and the maximum allowable total power Pok is set to 3000W, the maximum operating current of the system is 25A. In another embodiment, the rated power of the heating modules corresponding to the preheating boiler and the high-temperature boiler can both be set to 2500W, so that even when the rated total power of the two boilers is higher than the maximum allowable total power, the overall power supply constraint can still be met through the coordinated control of S3 to S5.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-power intelligent control method for dual steam boilers, characterized in that: The control method includes the following steps: S1. Real-time monitoring of the temperature of the preheating boiler and the high-temperature boiler using temperature sensors; S2. Based on the set steam temperature, perform closed-loop control calculations on the preheating boiler and the high-temperature boiler respectively to obtain their respective heating power requirements; S3. Calculate the sum of the heating power requirements of the preheating boiler and the high-temperature boiler. When the sum of the heating power requirements exceeds the preset total heating power limit, allocate the heating power of the preheating boiler and the high-temperature boiler through a power optimization allocation mechanism so that the total heating power after allocation does not exceed the total heating power limit. S4. Based on the allocated heating power, configure the corresponding power control mode for the preheating boiler and the high-temperature boiler respectively and execute heating; S5. During the heating process, the heating start-up sequence of the preheating boiler and the high-temperature boiler is optimized and controlled to avoid both starting heating simultaneously.

2. The low-power consumption intelligent control method for a steam dual boiler according to claim 1, characterized in that: The closed-loop control calculation in S2 is PID control. Specifically, based on the temperature difference between the target temperature and the actual temperature of the preheating boiler and the high-temperature boiler, PID calculations are performed to obtain the corresponding heating power requirements.

3. The low-power consumption intelligent control method for a steam dual boiler according to claim 1, characterized in that: The maximum allowable total power of the boilers is a pre-set maximum allowable total power of the two boilers, which is used to limit the real-time total heating power of the preheating boiler and the high-temperature boiler. The maximum allowable total power is 3kW, and through the optimized allocation in S3, the real-time total heating power of the two boilers is controlled within 3kW.

4. The low-power consumption intelligent control method of a steam dual boiler according to claim 1, characterized in that: The power supply system used by the boiler is 220VAC / 50Hz or 120VAC / 60Hz, and one sine wave cycle is defined as one electrical cycle.

5. The low-power consumption intelligent control method of a steam dual boiler according to claim 1, characterized in that: The power control method in S4 adopts a zero-crossing start method and a cycle control method. By controlling the number of electrical cycles conducted in each control cycle, different heating power levels can be achieved.

6. The low-power intelligent control method for dual steam boilers according to claim 5, characterized in that: In the aforementioned frequency control method, the maximum control cycle is 10 electrical cycles, and the power control timing is configured according to the corresponding frequency of the preheating boiler and the high-temperature boiler.

7. The low-power consumption intelligent control method of a steam dual boiler according to claim 1, characterized in that: The optimized control in S5 includes: configuring the turn-on sequence of the preheating boiler and the high-temperature boiler in a staggered manner according to the final output power allocated to them, so as to avoid the two boilers starting heating simultaneously in the same electrical cycle.

8. The low-power consumption intelligent control method of a steam dual boiler according to claim 1, characterized in that: The boiler's steam generation system adopts a two-stage structure. Cold water first enters the preheating boiler for preheating, and then enters the high-temperature boiler for vaporization, in order to avoid the sudden drop in temperature and pressure fluctuation caused by cold water directly entering the high-temperature boiler.

9. The low-power consumption intelligent control method of a steam dual boiler according to claim 4, characterized in that: When the power supply system is 120VAC and the maximum allowable total power of the boiler is 3000W, the maximum operating current of the boiler's steam generation system during operation is 25A.

10. A low power consumption intelligent controller for a steam dual boiler, characterized by: Used to operate the low-power intelligent control method for dual steam boilers as described in any one of claims 1-9.

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