Modular electrically heated steam boiler system and intelligent control method thereof

Abstract

The application discloses a modular heat-conducting medium electric heating steam boiler system and an intelligent control method thereof, and belongs to the technical fields of electric heating steam boilers and high-voltage electric heating conversion. The system comprises a high-voltage electric control unit, a high-voltage water supply unit and a preheating module, an evaporation module and a superheating module which are sequentially and fluidly connected along the flow direction of a working medium. The high-voltage electric control unit comprises a rectifier device, a filter and protection circuit, a direct-current bus capacitor and multiple groups of power controllers which are sequentially connected. The output ends of the multiple groups of power controllers are respectively connected to the preheating module, the evaporation module and the superheating module. The preheating module, the evaporation module and the superheating module all adopt a pressure-bearing cylinder as an outer shell, and a plurality of dry heating jacket pipes are suspendedly arranged in the pressure-bearing cylinder along an axial direction. The dry heating jacket pipes are used for heating the working medium. The system adopts a hierarchical modular design and an efficient heat-conducting medium heat transfer technology, and a step-down transformer is omitted. The system is directly driven by high voltage without a transformer, has high heat exchange efficiency, prevents dry burning and has a compact structure.

Description

Technical Field

[0001] This invention relates to the field of electric steam boilers and high-pressure electrothermal conversion technology, specifically to a modular heat transfer medium electric steam boiler system and its control method. Background Technology

[0002] Traditional coal-fired, oil-fired, and gas-fired industrial boilers are gradually being replaced by clean and efficient electric boilers. Compared with fossil fuel boilers, electric boilers have significant advantages such as zero emissions, low noise, and high automation, making them an important development direction for future industrial steam supply. However, as industrial applications increasingly demand higher steam quality (such as superheated steam) and higher unit power (megawatt level and above), the limitations of traditional electric boilers in terms of voltage level, heat exchange efficiency, and structural layout are becoming increasingly apparent.

[0003] Currently, industrial electric boilers are mainly divided into two categories: low-pressure resistance boilers and high-pressure electrode boilers. Low-pressure resistance boilers mostly use 380V or 690V power supply. For high-power applications, expensive and bulky step-down transformers are required, which not only increases the system's footprint and steel consumption but also brings significant line losses, which does not conform to the development trend of compactness and low carbon emissions. Although high-pressure electrode boilers achieve high-pressure direct drive, they use water as a conductive medium, which requires extremely high water conductivity. Furthermore, they pose a safety hazard during operation due to electrolysis gas production (hydrogen-oxygen mixture), and it is difficult to stably produce high-quality superheated steam.

[0004] To address the challenges of high-voltage insulation and water-electricity separation, dry-type bushing heating technology has been gradually introduced. Existing dry-type heating structures are mostly found in small heaters. For example, while CN204665658U, applied for by Henan Laipake Chemical Equipment Manufacturing Co., Ltd., achieves physical isolation between the heating element and the working fluid, a tiny air gap usually exists between the heating rod and the inner wall of the bushing. The extremely low thermal conductivity of the air layer results in high contact thermal resistance, making heat conduction difficult and easily causing "localized dry burning" of the electric heating rod due to heat accumulation, severely shortening the equipment's lifespan. Although some studies have proposed using highly efficient thermally conductive media to fill the gaps to enhance heat transfer, existing high-efficiency thermally conductive media heating devices are mostly simple structures, lacking a complete and visualized sealing and expansion compensation mechanism. Under long-term high-temperature operation, the highly efficient thermally conductive media is prone to oxidation failure or leakage, limiting its engineering application in industrial boilers.

[0005] Furthermore, traditional electric steam boilers mostly adopt an integral vertical cylindrical structure, such as CN107869844A applied for by Beijing Powerport Technology Co., Ltd., which aims to solve the problem of heat accumulation or heat transfer loss during the conversion process. However, the vertical structure has two major drawbacks: first, maintenance is difficult, and replacing heating components often requires large hoisting equipment for high-altitude operations; second, the flow field organization is monotonous, and the single cylindrical structure cannot simultaneously meet the differentiated requirements of flow velocity and disturbance for the three thermodynamic stages of preheating (single-phase flow), evaporation (two-phase flow), and superheating (gas phase flow), easily forming dead flow zones at the bottom, leading to scaling and tube rupture. In summary, the currently applied electric boiler patent technologies are still at the level of partial improvements to traditional vertical structures or low-pressure heating methods, without fundamental innovation and transformation from the underlying logic of high-pressure direct drive and enhanced heat transfer.

[0006] Horizontal modular structures offer advantages such as a low center of gravity, good seismic resistance, and ease of skid-mounted transport, while also facilitating the design of differentiated flow channel structures for different phase change stages. Furthermore, highly efficient heat transfer medium immersion heat exchange technology can completely eliminate contact thermal resistance, achieving stable transmission of high heat flux. Therefore, improving the high-efficiency heat transfer medium dry-shell technology and combining it with a horizontal, staged modular design for use in high-pressure electric steam boilers is a highly promising and effective approach.

[0007] Current electric boiler control technologies are mostly based on fixed PID parameters, which cannot adapt to load changes in high-pressure series heating rod assemblies after partial failures or maintenance replacements. There is an urgent market need for a modular electric steam system that can be directly connected to 10kV / 35kV high voltage, possesses excellent insulation and heat transfer performance, and can achieve adaptive safety control through impedance identification, to meet the pressing needs of oilfield steam injection and industrial high-pressure steam. Summary of the Invention

[0008] To address the problems of existing high-pressure, high-power electric steam boilers, such as high cost and large footprint due to reliance on step-down transformers, low heat transfer efficiency and easy oxidation due to air thermal resistance in traditional dry-coil systems, dead zones in the flow field of vertical single-structure boilers and difficulties in maintenance, and overpressure safety hazards caused by the lack of adaptive control strategies, this invention aims to provide a modular, high-efficiency thermally conductive medium steam boiler system and its control method based on dry-coil heat exchange. This invention utilizes immersion heat exchange with a high-efficiency thermally conductive medium to eliminate contact thermal resistance, optimizes the flow field through a horizontal, staged, modular design, and combines an impedance identification adaptive control strategy to achieve inherently safe and efficient operation under 10kV / 35kV high-voltage direct drive.

[0009] To achieve the above objectives, the present invention provides a modular heat transfer medium electric steam boiler system, comprising a high-voltage electrical control unit, a high-voltage feedwater unit, and a preheating module, an evaporation module, and a superheating module that are sequentially fluidly connected along the working fluid flow direction; the high-voltage electrical control unit integrates an intelligent high-voltage topology switching matrix and a voltage sensing module; the electrical input terminals of the preheating module, the evaporation module, and the superheating module are all connected to the intelligent high-voltage topology switching matrix, and each of the preheating module, the evaporation module, and the superheating module includes several dry heating sleeves suspended along the axial direction, which are used to heat the working fluid; the high-voltage electrical control unit includes a rectifier, a filter and protection circuit, a DC bus capacitor, and multiple power controllers connected in sequence, and the output terminals of the multiple power controllers are respectively connected to the preheating module, the evaporation module, and the superheating module.

[0010] Furthermore, the system adopts an integrated skid-mounted layout, with the high-pressure water supply unit, preheating module, evaporation module, and superheating module all installed via skid-mounted bases. The high-pressure water supply unit includes a filter device, a water storage tank, and a variable frequency high-pressure water pump set in sequence along the working fluid flow direction. The system also includes a steam-water separator, whose input end is connected to the steam collection port of the evaporation module, and whose output end is connected to the input end of the superheating module.

[0011] Furthermore, the preheating module, evaporation module, and superheating module all adopt a pressure-bearing cylindrical structure. The dry heating jacket is a blind tube structure with one end open and the other end closed. The open end of the dry heating jacket is sealed and fixed to the tube sheet at the end of the cylinder, and the closed end extends into the inside of the cylinder with a gap between it and the inner wall of the cylinder. A working fluid heat exchange channel for water or steam circulation is formed between the inner wall of the pressure-bearing cylinder and the outer wall of the dry heating jacket.

[0012] Furthermore, several electric heating rods connected in parallel or series are inserted into the inner hole of the dry heating sleeve. The gap between the dry heating sleeve and the electric heating rods is filled with a high-efficiency heat-conducting medium. The heat generated by the electric heating rods is transferred to the dry heating sleeve through the high-efficiency heat-conducting medium.

[0013] Furthermore, the outer wall of the heating section of the electric heating rod assembly is directly immersed in the high-efficiency heat-conducting medium, and the dry heating sleeve constitutes a sealed cavity for the high-efficiency heat-conducting medium. Alternatively, the high-efficiency heat transfer medium heat exchange assembly may also include an inner isolation sleeve; the inner isolation sleeve is sleeved on the outside of the electric heating rod assembly and located inside the dry heating sleeve; the high-efficiency heat transfer medium is filled in the interlayer space formed between the outer wall of the inner isolation sleeve and the inner wall of the dry heating sleeve; the electric heating rod assembly conducts heat through contact with the inner wall of the inner isolation sleeve or through solid heat-conducting filler.

[0014] Furthermore, the open end of the dry heating jacket is provided with a connecting neck, and the top of the connecting neck is vertically connected to a visual fully sealed expansion compensation device; the visual fully sealed expansion compensation device includes a metal bellows, a fully sealed top cover, a liquid level indicator rod, and a visual protective shell, the lower end of the metal bellows is sealed to the connecting neck; the fully sealed top cover is sealed and fixed to the upper end of the metal bellows; the liquid level indicator rod is vertically fixed to the center of the fully sealed top cover, and the visual protective shell is covered on the outside and has a longitudinal observation window.

[0015] Furthermore, the working fluid heat exchange channel inside the preheating module is provided with a spiral enhanced heat transfer structure; the spiral enhanced heat transfer structure includes a spiral baffle plate sleeved on the outer periphery of the dry heating sleeve.

[0016] Furthermore, the working fluid heat exchange channel inside the evaporation module is provided with a vapor-liquid separation guide structure; the vapor-liquid separation guide structure includes several notched guide plates distributed axially between the dry heating sleeves; the notched guide plate is a circular plate, with a horizontal exhaust notch cut off at its top to form a top vapor phase channel for rapid steam discharge, and a water passage hole for liquid water to flow through at its bottom.

[0017] Furthermore, a vapor phase enhanced heat transfer structure is provided on the outer wall of the dry heating sleeve inside the overheating module, the vapor phase enhanced heat transfer structure including longitudinal heat dissipation fins extending along the axial direction of the dry heating sleeve.

[0018] Furthermore, it also includes a phase change auxiliary unit and a thermal expansion compensation pipeline; the phase change auxiliary unit includes a steam-water separator installed between the evaporation module and the superheating module and a steam buffer tank located at the end of the system, the top outlet of the evaporation module is connected to the inlet of the steam-water separator via a pipeline, and the dry steam outlet of the steam-water separator is connected to the inlet of the superheating module; Ω-shaped or U-shaped stress compensation bends are provided on the connecting pipelines between the evaporation module and the steam-water separator, and between the superheating module and the steam buffer tank.

[0019] Secondly, the present invention also provides an intelligent control method for the modular heat transfer medium electric steam boiler system as described above, comprising the following steps: Monitor the input voltage amplitude at the front end of the high-voltage electrical control unit; When the input voltage amplitude is within the first preset range, the intelligent high-voltage topology switching matrix is ​​controlled to reconstruct the preheating module, evaporation module and superheating module into an electrically parallel topology, and the first control strategy is executed; When the input voltage amplitude is within the second preset range, the intelligent high-voltage topology switching matrix is ​​controlled to reconstruct the preheating module, evaporation module and superheating module into an electrically connected topology, and the second control strategy is executed; Wherein, the maximum value of the first preset range is less than or equal to the minimum value of the second preset range.

[0020] Furthermore, the first control strategy includes: Load group integrity self-test steps: Before connecting the main power supply, inject diagnostic pulses into the electric heating rod group in each module, determine the insulation impedance and connection status of each group based on the response current, and lock the faulty group. Constant pressure group switching control steps: Under the condition of constant DC bus voltage, based on the deviation between the outlet temperature of the preheating module, the steam pressure in the evaporation module, or the outlet temperature of the superheating module and their respective target values, the power demand of each module is calculated by PID control, and the number of electric heating rod groups put into operation is independently controlled in a step manner.

[0021] Specifically, when the system executes the first control strategy (parallel modules - internal series connection), the control logic includes: S11, Load group integrity self-check: After the system is powered on, low-voltage diagnostic pulses are injected into the electric heating rod group circuits inside the preheating module, evaporation module and superheating module. The impedance and connection status of each group are determined according to the response current. If the status meets the operating conditions, the system enters the 10kV high-voltage ready state. If an abnormality is detected, the corresponding group is locked or the start is prohibited. S12, 10kV constant voltage group switching control, maintains a constant input voltage in the 10kV high voltage ready state. It calculates the real-time power demand of each module through a PID algorithm and converts the power demand into the corresponding number of heating rod connection groups. It controls the on / off of the high voltage switch group corresponding to each module. Based on the feed water temperature deviation, it adjusts the number of electric heating rod groups connected to the preheating module; based on the steam pressure deviation, it adjusts the number of electric heating rod groups connected to the evaporation module; based on the outlet temperature deviation, it adjusts the number of electric heating rod groups connected to the superheating module. S13, Operation protection and feedback real-time monitoring of high voltage leakage current and arc signal of the operation circuit. If the threshold is exceeded, emergency cut-off is triggered; if the limit is not exceeded, the temperature, pressure and liquid level parameters of the system are collected and fed back to step S12 to update the number of heating rod connected groups.

[0022] Furthermore, the second control strategy includes: Real-time impedance identification and safety clamping steps: Collect the total current of the series circuit and the voltage drop across each module, and calculate the real-time impedance of each module; calculate the voltage distribution coefficient based on the real-time impedance of each module, and deduce the maximum safe total voltage that the system can apply; Dynamic pressure balance control steps: Decoupling calculations are performed based on steam pressure deviation and outlet temperature deviation, and voltage regulation commands and water pump flow regulation commands are output respectively. The voltage regulation commands are arbitrated with the maximum safe total voltage as the limit, and the final target voltage is output.

[0023] Specifically, when the system executes the second control strategy (module series-internal parallel), the control logic adopts a dynamic voltage divider balance control strategy, including: S21, full-dimensional data acquisition: The control unit first acquires the total current of the series circuit and the voltage of each module in real time through the high-speed interface to construct a full-dimensional dataset. S22, real-time impedance identification and safety clamping, followed by identification of the real-time impedance of each module based on Ohm's law and calculation of the voltage distribution coefficient, and inverse calculation of the maximum total voltage that the system can be allowed to apply ( S23, dual closed-loop decoupling operation: during the operation phase, a dual closed-loop decoupling algorithm for pressure main and temperature secondary control is adopted to calculate voltage regulation command and frequency conversion flow command respectively. S24, Multimodal logic execution, automatically configures the topology state of flow channel valves and electrical bypass switches according to the user-defined hot water, saturated steam or superheated steam mode; S25, hardware driver and arbitration, executes critical voltage instruction arbitration logic before hardware driver execution, forcibly limiting the final output voltage to the PID demand value and the maximum safe total voltage. The smaller value of ) completely eliminates the risk of local overvoltage breakdown caused by load impedance imbalance in high-voltage series systems from the bottom layer of the control algorithm, ensuring the inherent safety and stable operation of the system under 35kV high-voltage direct drive conditions.

[0024] Furthermore, the second control strategy also includes a multimodal logic execution step: automatically configuring the working fluid flow path and electrical topology of the system according to the target steam mode set by the user; the target steam mode includes hot water mode, saturated steam mode and superheated steam mode.

[0025] This invention provides an intelligent control method for the aforementioned modular heat transfer medium electric steam boiler system. The control unit is pre-set with two intelligent electrical connection control strategies for the preheating module, evaporation module, and superheating module: the first control strategy is applicable to the case where the electrical input terminals of each module are connected in parallel to a 0-10kV power supply and the internal heating rod groups are connected in series; the second control strategy is applicable to the case where the electrical input terminals of each module are connected in series to a 10-35kV power supply and the internal heating rod groups are connected in parallel; after the system is powered on, the control unit first performs a topology self-test to identify the current hardware connection method and automatically loads the corresponding impedance identification and voltage driving algorithm.

[0026] Furthermore, both the first and second control strategies include efficient thermal inertia compensation via a heat-conducting medium and multivariable decoupling steps. Thermal inertia compensation: The control unit has a built-in heat capacity model of the high-efficiency heat-conducting medium. When the system changes operating conditions, it introduces feedforward control quantity according to the current temperature and heating rate of the high-efficiency heat-conducting medium to adjust the SCR output power in advance to compensate for the temperature response lag caused by the heat absorption of the high-efficiency heat-conducting medium. Multivariate decoupling: Pressure control: The pressure deviation of the steam header is used as the main feedback quantity to adjust the power weight of the evaporation module; Temperature secondary control: Using the outlet superheat deviation as secondary feedback quantity, the flow rate of the variable frequency high-pressure water pump unit and the power weight of the superheat module are adjusted. Preheating coordination: Based on the water supply flow rate and inlet water temperature, the basic power command of the preheating module is automatically calculated to ensure that the water temperature entering the evaporation module remains constant near the saturation temperature.

[0027] Furthermore, the intelligent control method also includes a circuit breakage and leakage monitoring step: during the system operation cycle, the current waveform of each module heating rod group is monitored in real time; if the voltage is normal but the current drops to zero instantly, it is determined that the circuit is broken, the power supply of the faulty module is immediately cut off and the operation of the remaining modules is maintained; if an abnormal change in the nonlinear impedance of the heating rod group is detected, it is determined that the high-efficiency heat conduction medium is leaking or dry burning, and an emergency shutdown is immediately executed.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention discloses a modular heat transfer medium electric steam boiler system, which utilizes a hierarchical modular design and efficient heat transfer medium technology to achieve direct access to 10kV or even 35kV high-voltage power supply, eliminating the need for expensive and bulky step-down transformers, significantly reducing the initial investment and floor space of the system, and conforming to the development trend of high-pressure and compact electric boilers.

[0029] Furthermore, the system adopts an integrated skid-mounted layout, highly integrating the high-pressure water supply, three-stage heat exchange modules, and phase change auxiliary units onto the same base. The structure is compact, facilitating transportation and rapid on-site installation. The modular design supports online maintenance and fault isolation. When a group of heating rods or modules fails, the faulty unit can be disconnected through control strategies or the heating rod can be replaced online using the connecting neck pipe, without shutting down the entire system, which greatly improves the continuity and reliability of steam supply.

[0030] Furthermore, this invention employs a dry heating sleeve combined with a heat exchange structure filled with a highly efficient heat-conducting medium, which completely eliminates the air contact thermal resistance present in traditional dry heating, achieving physical isolation and efficient heat conduction between the electric heating rod and the working medium; it not only solves the problems of high-voltage insulation and water-electricity separation, but also effectively avoids dry burning and heating rod melting caused by local overheating, significantly extending the service life of the core heating element.

[0031] Furthermore, this invention achieves fully enclosed operation of the high-efficiency heat transfer medium system by combining a connecting neck tube with a visualized fully sealed expansion compensation device. The high-efficiency heat transfer medium that expands due to heat enters the upper metal bellows through the connecting neck tube. The expansion and contraction of the bellows, combined with the fully sealed top cover, isolates external air, completely solving the problem of oxidation failure of the high-efficiency heat transfer medium under long-term high-temperature operation. At the same time, the injection and discharge ports on the side wall of the connecting neck tube support online filling and discharging of the high-efficiency heat transfer medium without disassembling the sleeve, realizing furnace shutdown or rapid maintenance.

[0032] Furthermore, the system adopts a horizontal, staged, modular design, matching differentiated flow fields to the physical characteristics of the three stages: preheating, evaporation, and superheating. The spiral baffles in the preheating module force liquid water to flow along the outer wall of the casing in a spiral path, generating strong rotating turbulence to flush the pipe wall and delay scaling. The notched guide plates in the evaporation module force the vapor-liquid two-phase fluid to move forward in a wave-like manner, using gravity to achieve vapor-liquid separation and prevent heat transfer deterioration caused by gas film coverage. The longitudinal fins in the superheating module increase the gas phase heat exchange area and reduce the heat load on the pipe wall. The horizontal arrangement combined with the forced flow guiding structure helps to eliminate the flow dead zone at the bottom of the vertical boiler, significantly reducing the risk of scaling and tube rupture.

[0033] Furthermore, the intelligent control method of this invention has extremely high flexibility and safety, and presets two adaptive strategies: "module parallel connection - internal series connection" and "module series connection - internal parallel connection", which can be compatible with power grids of different voltage levels. For 0-10kV direct drive scenarios, the innovative load integrity self-check and constant voltage group switching control eliminate the risk of short circuit closing from the source and realize fine step adjustment of power. For 0-35kV series scenarios, dynamic voltage balance control effectively avoids the risk of overvoltage breakdown caused by series imbalance.

[0034] Furthermore, the intelligent control system incorporates high-efficiency heat transfer medium thermal inertia compensation and multivariable decoupling algorithms. By utilizing feedforward control, it overcomes the temperature response lag caused by the large heat capacity of the high-efficiency heat transfer medium, achieving precise coordinated control of steam pressure, outlet temperature, and feedwater flow rate. This ensures stable output of high-quality superheated steam even under fluctuating load conditions. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the modular high-efficiency heat transfer medium steam boiler system based on dry-shell heat exchange according to the present invention.

[0036] Figure 2a This is an overall structural diagram of the high-efficiency thermal conductivity heat exchange component in this invention, showing the cooperation relationship between the multi-bar bundle and the dry sleeve, as well as the distribution of the high-efficiency thermal conductivity medium inside the dry sleeve when the high-efficiency thermal conductivity heat exchange component has or does not have an inner isolation sleeve. Figure 2b yes Figure 2aA partially enlarged cross-sectional schematic diagram of the fully sealed, visual expansion compensation device shows the structure with the lower part containing the expanding metal and the upper part being visualized. Figure 2c yes Figure 2a A cross-sectional view of the fixed end of a medium- and high-efficiency thermal conductivity heat exchanger assembly shows the situation where the high-efficiency thermal conductivity medium in a multi-bar bundle converges at the fixed end. Figure 2d A cross-sectional schematic diagram for visualizing the fully sealed expansion compensation device.

[0037] Figure 3a This is a schematic diagram of the overall appearance structure of the preheating module (R1) of the present invention, showing the assembly relationship between the horizontal pressure-bearing shell and the high-efficiency heat transfer medium heat exchange component; Figure 3b This is a schematic diagram of the structure of the core heat exchange element inside the preheating module in this embodiment of the invention, which focuses on the spiral baffle structure sleeved on the outer periphery of the dry heating sleeve; Figure 3c This is a cross-sectional view of the internal assembly of the preheating module in an embodiment of the present invention, showing the flow channel division arrangement of the spiral baffles in the pressure-bearing shell.

[0038] Figure 4a This is a schematic diagram of the overall appearance structure of the evaporation module in this invention, showing the connection between the external pressure-bearing shell and the front-end high-efficiency heat exchange medium component; Figure 4b This is a schematic diagram of the internal structure of the evaporation module after the outer shell is removed in this invention, which focuses on showing the cooperation relationship between the dry heating sleeve assembly and the notched guide plates distributed along the axial direction; Figure 4c This is a schematic diagram of the cross-sectional structure of the notched guide plate inside the evaporation module in this invention, showing in detail the distribution of the top steam exhaust notch, the heating rod holes in the middle, and the water passage holes at the bottom. Figure 4d This is a schematic diagram of a partial structure within the evaporation module.

[0039] Figure 5 This is a schematic diagram of the structure and connection of the steam-water separator and the terminal pipeline valve group in this invention, showing the pipeline connection relationship of the separator as the end point of the system for final steam-water separation and steam supply to users.

[0040] Figure 6a This is a schematic diagram of the overall appearance structure of the overheating module in this invention, showing the assembly form of the overheating pressure shell and the high-efficiency heat transfer medium heat exchange component; Figure 6b This is a three-dimensional structural diagram of the high-efficiency heat exchange medium inside the overheating module in this invention, which focuses on the longitudinal heat dissipation fin structure set on the outer wall of the dry heating sleeve. Figure 6c This is a schematic diagram of the cross-sectional structure of the overheating module in this invention, showing the array arrangement of the finned heating sleeves within the pressure-bearing housing.

[0041] Figure 7aThis is the overall logical topology diagram of the modular high-efficiency heat transfer medium steam boiler system based on dry-shell heat exchange of the present invention. It macroscopically shows the energy and working fluid flow relationship between the high-pressure power supply module, water treatment module, heating modules at all levels and control unit. In order to clearly distinguish different types of flow, different line types are used: thick solid lines represent the transmission path of high-pressure direct current (DC), medium thick solid lines represent the physical flow pipeline of the working fluid (water / steam), and thin dashed lines represent the transmission path of control signals and sensor feedback data.

[0042] Figure 7b This is a schematic diagram of the high-voltage power supply and control subsystem of the present invention, which shows in detail the rectification and filtering process of high-voltage AC to DC conversion, as well as the electrical connection logic between the PLC controller and various sensors and actuators. Figure 7c This is a flow chart of the water supply and preheating subsystem (liquid phase section) of the present invention, which shows the process flow of the working fluid water from the source through filtration, pressurization, metering until the first stage of preheating is completed; Figure 7d This is a flowchart of the evaporation and steam-water separation system (phase change section) of the present invention, which shows in detail the cascade relationship between the evaporation module and the steam-water separation device, and embodies the dry steam preparation process of producing and separating it on the spot. Figure 7e This is a flowchart of the superheating and terminal distribution subsystem (gas phase section) of the present invention, which shows the further superheating of dry steam, pressure stabilization and buffering, and multi-path distribution logic for three different user needs: hot water, saturated steam, and superheated steam.

[0043] Figure 8a This is a flowchart of the control program for parallel-internal series connection of modules under 0-10kV according to the present invention; Figure 8b This is a flowchart of the control program for the series-internal parallel connection of modules under 10-35kV of the present invention.

[0044] In the attached diagram: 100 - Skid-mounted base; 200 - High-voltage electrical control unit; 300 - High-pressure water supply unit; 301 - Filter device; 302 - Water storage tank; 303 - Variable frequency high-pressure water pump set; 400 - Preheating module; 401 - Preheating pressure-bearing shell; 402 - Spiral baffle; 500 - Evaporation module; 501 - Evaporation pressure-bearing shell; 502 - Notched guide plate; 5021 - Exhaust notch; 5022 - Water passage hole; 600 - Superheating module; 601 - Superheating pressure-bearing shell; 602 - Longitudinal diffuser Heated fins; 700-High-efficiency heat transfer medium heat exchange assembly; 701-Dry heating jacket; 702-Electric heating rod assembly; 703-High-efficiency heat transfer medium; 704-Connecting neck tube; 800-Visualized fully sealed expansion compensation device; 801-Metal bellows; 802-Fully sealed top cover; 803-Liquid level indicator rod; 804-Visualized protective shell; 900-Steam-water separator; 901-Ω-type stress compensation bend; 902-Rising steam collection pipe; 903-Superheated steam outlet pipe; 904-Steam buffer tank.

[0045] A-High Voltage Power Supply and Control Module: 1-Grid Input; 2-Rectifier; 3-Filter / Overvoltage Protection Circuit; 4-Power Controller (SCR); 5-DC Bus Capacitor; B-Water Pretreatment Module: 6-Water Source Inlet; 7-Softening / Desalination Device; 8-Variable Frequency High Voltage Water Pump; 9-Check Valve; FT-01-Inlet Flow Meter; C-Preheating Module (R1): R1-Preheating Module Body; TT-01-Preheating Outlet Temperature Sensor; SV-01-First Stage Safety Valve; D-Evaporation Module (R2): R2- Evaporation module body; PT-01 - Evaporation pressure sensor; 10 - Steam-water separator; SV-02 - Secondary safety valve; E - Superheat module (R3): R3 - Superheat module body; TT-02 - Outlet temperature sensor; SV-03 - Tertiary safety valve; F - Storage and distribution module; 11 - Steam buffer tank; V1 - Hot water switching valve; V2 - Saturated steam switching valve; V3 - Main steam valve (superheated steam); PLC - Main controller: connects to various sensors (TT / PT / FT) and actuators (pump / valve / SCR). Specific implementation methods 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, not all, of the embodiments of the present invention. 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.

[0046] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] Example 1, such as Figure 1As shown, the present invention provides a modular high-efficiency heat transfer medium steam boiler system based on dry-shell heat exchange. The system is designed with a rated voltage of 10kV, a maximum voltage of 35kV, a rated evaporation capacity of 4t / h, and a design pressure of 1.6MPa. The system adopts an integrated skid-mounted structure, with all components integrated onto a reinforced carbon steel skid base 100 measuring 6000mm × 2500mm. This includes the skid base 100, a high-voltage electrical control unit 200, a high-voltage water supply unit 300 located at the front end of the skid base 100, and a preheating module 400, an evaporation module 500, and a superheating module 600 sequentially connected along the working fluid flow direction. The high-voltage electrical control unit 200 integrates an intelligent high-voltage topology switching matrix and a voltage sensing module. The preheating module 400, evaporation module 500, and superheating module 600 all use pressure-bearing cylinders as their outer shells, and the electrical input terminals of all three modules are connected to the intelligent high-voltage topology switching matrix. The voltage sensing module collects the grid input voltage in real time, and the control unit automatically controls the opening and closing of each contactor within the intelligent high-voltage topology switching matrix based on the input voltage amplitude of 0-35kV. The electrical connection topology of the three modules is dynamically reconfigured, allowing them to switch freely between fully parallel, partially series-parallel, or fully series states. Each module's pressure-bearing cylinder has several dry heating sleeves 701 suspended axially inside. Each dry heating sleeve 701 is a blind tube structure with one open end and the other closed. Its open end is sealed and fixed to a tube sheet at the end of the cylinder, while its closed end extends into the cylinder, with a gap between it and the inner wall of the pressure-bearing cylinder. Several parallel or series-connected electric heating rod groups 702 are inserted into the inner hole of the dry heating sleeve 701. The gap between the dry heating sleeve 701 and the electric heating rod groups 702 is filled with a high-efficiency heat-conducting medium 703. The heat generated by the electric heating rod groups 702 is transferred to the dry heating sleeve 701 via the high-efficiency heat-conducting medium 703. A working fluid heat exchange channel for water or steam circulation is formed between the inner wall of the pressure-bearing cylinder and the outer wall of the dry heating sleeve 701.

[0048] refer to Figure 1 , Figure 7a , Figure 7b and Figure 7cThe high-pressure water supply unit 300 is located on the right side of the front end of the skid-mounted base 100. The high-pressure water supply unit 300 includes a filter device 301, a water storage tank 302, and a variable frequency high-pressure water pump set 303 connected in sequence. The variable frequency high-pressure water pump set 303 consists of two vertical multi-stage centrifugal pumps, one for standby and one for operation. An external water source is connected to the filter device 301 located on the far right of the base via a pipeline. The water, after preliminary purification, flows through a pipeline into the water storage tank 302 located immediately to its left. The water storage tank 302 serves to buffer the water supply and stabilize the pressure before the pump. The bottom outlet of the water storage tank 302 is connected to the main water inlet pipe of the variable frequency high-pressure water pump set 303 via a pipeline. The outlet pipe of the variable frequency high-pressure water pump set 303 uses a DN40 stainless steel high-pressure pipe and is connected in series with a check valve 9, an electric regulating valve, and an inlet flow meter (FT-01). The working fluid flows sequentially through three horizontally cascaded heating modules: the preheating module 400, the evaporation module 500, and the superheating module 600. The outlet of the variable frequency high-pressure water pump set 303 is connected to the inlet at the bottom of the preheating module 400; the outlet at the top of the preheating module 400 is connected to the inlet at the bottom of the evaporation module 500 via a pipe. The steam collection port on the side of the evaporation module 500 is tangentially connected to the steam-water separator 900 via a DN80 rising steam collection pipe 902. The steam-water separator 900 is fixedly mounted at the highest physical point between the evaporation module and the superheating module. Its bottom has a return water pipe connected to a tee pipe from the outlet of the variable frequency high-pressure water pump set 303 to the inlet of the preheating module 400, returning the water to the preheating module 400. The top of the steam-water separator 900 has an Ω-shaped stress-compensating bend 901 to absorb the thermal displacement caused by the temperature difference between the steam-water separator 900 and the evaporation module 500. The outlet of the superheating module 600 is connected to the steam buffer tank 904 via the superheated steam outlet pipe 903, and finally output to the user's pipeline network via the main steam valve V3. In terms of electrical layout, the high-voltage electrical control unit 200 is located in the low-voltage safety area (front left) of the skid-mounted base. Internally, it integrates a three-phase full-bridge rectifier 2, an LC filter and protection circuit 3, a DC bus voltage stabilizing capacitor 5, three independent SCR thyristor voltage regulating cabinets 4, and a PLC main control module. The outputs of the three SCR voltage regulating cabinets are connected to the junction boxes of the preheating module 400, evaporation module 500, and superheating module 600 respectively via high-voltage shielded cables, enabling independent voltage regulation control of the three-phase loads.

[0049] Example 2, such as Figure 2a , Figure 2c , Figure 4d and Figure 6cAs shown, each pressure-bearing shell contains 12 high-efficiency heat exchanger components 700 evenly arranged. This component is the core heat exchange unit of the system, and its exterior is a dry heating jacket 701, made of seamless steel pipe of Inconel 625 or 310S heat-resistant stainless steel, with a specification of Φ89×6mm. The dry heating jacket 701 is a blind tube structure with one end open and the other end closed. The open end is welded to the fixed end of the tube sheet; the closed end extends horizontally into the shell in the form of a cantilever beam, with a suspended length of 3500mm. A 50mm thermal expansion gap is maintained between the end and the rear end cap of the shell to ensure that the jacket can freely expand and contract at high temperatures, completely eliminating the temperature difference stress of traditional fixed tube sheet heat exchangers. Inside the dry heating jacket 701, an electric heating rod assembly 702 is inserted. The electric heating rod assembly 702 consists of 4 high-voltage electric heating rods with a diameter of Φ16mm arranged closely in a quincunx pattern. The electric heating rods are positioned by alumina ceramic supports, maintaining a spacing of 2mm. When the dry heating sleeve 701 adopts a direct immersion structure, a high-efficiency heat-conducting medium 703 (in this embodiment, a tin-bismuth eutectic alloy with a melting point of 124°C and a boiling point of 1670°C, i.e., a liquid metal) is vacuum-filled in the gap between the inner wall of the sleeve and the heating rod assembly. The liquid metal level covers the entire length of the heating section of the heating rod. Utilizing its extremely high thermal conductivity (approximately 80-100 times that of air), the heat generated by the electric heating rod assembly 702 is instantly transferred to the outer wall of the sleeve, solving the dry-burning problem caused by the thermal resistance of the air gap.

[0050] like Figure 2b and Figure 2c As shown, a connecting neck 704 with two 150mm long sections is embedded in the fixed end of the tube sheet. When the heating rod needs to be replaced, if the dry heating sleeve 701 adopts an internal isolation sleeve structure, the electric heating rod assembly 702 and the liquid metal heat transfer medium 703 are physically isolated. The liquid metal heat transfer medium 703 is sealed between the outer wall of the internal isolation sleeve and the inner wall of the dry heating sleeve 701, allowing maintenance personnel to directly pull out the heating rod assembly. If the dry heating sleeve adopts a direct immersion structure, maintenance personnel can open the drain port and use a siphon or suction tool to extract the liquid metal through the connecting neck 704, easily pulling out the heating rod assembly 702 without disassembling the entire unit, greatly reducing maintenance difficulty. A visual, fully sealed expansion compensation device 800 is connected to the vertical flange at the top of the connecting neck 704. The core of this device is a 316L metal bellows 801, whose effective stroke meets the liquid metal volume expansion rate (approximately 3%). A fully sealed top cover 802 is welded to the upper end of the bellows, and a liquid level indicator rod 803 extending to the outside is connected to the center of the top cover. The outer cover is equipped with a graduated, visual protective shell 804 (transparent high borosilicate glass or stainless steel tube with magnetic flip). This structure achieves absolute physical isolation between the liquid metal system and the atmosphere (zero leakage, zero oxidation), while maintenance personnel can visually inspect the liquid level.

[0051] Example 3: In order to solve the problems of dead flow corners and uneven heat exchange at the bottom of the horizontal cylinder, this embodiment designs specific internal components for the three modules.

[0052] like Figure 3a , Figure 3b , Figure 3c and Figure 7c As shown, the working fluid in the preheating module 400 is single-phase liquid water. To enhance convective heat transfer, a set of spiral baffles 402 are tightly fitted onto the outer wall of the high-efficiency thermally conductive medium heat exchange component 700. The spiral baffles 402 are continuously cold-wound from a 3mm thick stainless steel strip with a pitch of 200mm and a helix angle of 15°. The outer edge of the baffles is tightly fitted to the inner wall of the preheating pressure shell 401 (gap <1mm). This structure forcibly divides the originally straight annular flow channel into a long spiral channel. When the fluid flows through the heating tube bundle, the tangential velocity component increases significantly, generating strong rotating turbulence. The scouring effect of the rotating turbulence not only increases the heat transfer coefficient by more than 30%, but also effectively prevents suspended matter from depositing on the tube wall, playing a role in online self-cleaning.

[0053] like Figure 4a , Figure 4b , Figure 4c , Figure 4d and Figure 7d As shown, the working fluid in the evaporation module 500 is a vapor-liquid two-phase mixture. To prevent steam from accumulating and forming a film (film boiling), eight notched guide plates 502 are axially spaced inside the evaporation pressure shell 501. These guide plates are circular steel plates, 10mm thick. A portion of the top of each plate is cut away, forming an exhaust notch 5021, with the central angle corresponding to the area enclosed by the arc and chord being 120°. Several Φ30mm diameter water passage holes 5022 are opened at the bottom of the cut portion of each plate, forming an upper notch and lower opening structure. This forces liquid water to flow rapidly to the next stage through the bottom holes, while the generated steam quickly converges into the upper steam space through the top notch. The fluid exhibits a wave-like flow during horizontal propulsion, utilizing gravity difference to achieve immediate production and separation, ensuring that the surface of the dry heating jacket 701 is always wetted with liquid water, maintaining efficient nucleation boiling.

[0054] like Figure 6a , Figure 6b and Figure 6cAs shown, within the superheated module 600, a dry heating jacket 701 is installed inside the superheated pressure shell 601, using dry steam with a low thermal conductivity as the working fluid. To reduce the pipe wall temperature, eight longitudinal heat dissipation fins 602 are welded to the outer wall of each dry heating jacket 701 using a high-frequency welding process. These fins are made of 304 stainless steel, 25 mm high, and 1 mm thick, and are arranged parallel to the pipe axis. The fins expand the gas-side heat exchange area by approximately three times. At the same steam flow rate, this significantly reduces the surface heat load of the high-efficiency heat transfer medium heat exchange component 700, preventing pipe wall overheating and bursting due to deterioration of steam-side heat exchange.

[0055] like Figure 8a and Figure 8b As shown, the PLC controller equipped in this system operates an adaptive intelligent control algorithm. Upon power-up, after the system is connected to the power supply, the PLC first detects the actual amplitude of the input voltage at the front end (fluctuating continuously between 0 and 35kV) through the high-voltage voltage transformer (PT): Low-voltage high-current mode (0~10kV): The PLC determines that the system is in the low-voltage range and immediately sends a control command to close the parallel contactor group in the intelligent high-voltage topology switching matrix and disconnect the series contactor group, reconstructing the R1, R2, and R3 modules into a parallel topology in the physical circuit. Simultaneously, the system background automatically retrieves and runs the above first control strategy, achieving precise temperature and voltage control under low voltage by adjusting the SCR conduction angle and group switches; High-voltage low-current mode (10~35kV): The PLC determines that the system is in the high-voltage range and immediately sends a control command to close the series contactor group and disconnect the parallel contactor group, reconstructing the R1, R2, and R3 modules into a fully series topology to increase the total system impedance and prevent single-stage modules from being broken down by high voltage. Simultaneously, the system automatically retrieves and runs the aforementioned second control strategy, initiating a dynamic voltage divider balancing algorithm based on real-time impedance identification to ensure the safety of each module. After completing the macroscopic topology reconstruction, for any specific non-standard voltage value (such as 22kV or 8kV) within the 0~35kV range, the PLC can continuously chop and adjust the voltage (i.e., fine-tuning) by adjusting the conduction angle of the SCR power controller at high speed, thereby achieving true wide voltage free switching and intelligent self-adaptation across the entire 0~35kV range.

[0056] Example 4, such as Figure 1 , Figure 7a , Figure 7c , Figure 7d , Figure 7e and Figure 8a As shown, this embodiment is applied to a scenario where the high-voltage electrical control unit 200 is electrically connected in parallel with the preheating module 400, the evaporation module 500, and the superheating module 600. The method is executed by the PLC main controller within the high-voltage electrical control unit 200 and specifically includes the following three stages: S11: Load group integrity self-test phase. After the system is powered on, before the main circuit breaker is closed to introduce 10kV high voltage, the PLC main controller, in conjunction with the detection circuit within the high-voltage electrical control unit 200, executes the following logic (refer to...). Figure 8a The PLC sends test commands to the high-voltage switch groups (integrated in the SCR power controller group 4 or as independent contactor groups) connected to the preheating module 400, evaporation module 500, and superheating module 600 respectively; it sequentially activates each group channel, injecting low-voltage diagnostic pulses into the electric heating rod group 702 inside each module; the current transformer collects the response current of the circuit ( The PLC calculates the real-time insulation impedance and connectivity status of each group based on this. If an abnormal impedance (short circuit or open circuit) is detected in a group, the PLC will logically lock the switch channel corresponding to the faulty group and prohibit it from being put into operation. If the number of all groups or healthy groups that meet the minimum operating requirements is up to standard, the PLC determines that the system self-test has passed and allows the 10kV power supply to be connected. The system then enters the 10kV high-voltage ready state.

[0057] S12: During the 10kV constant voltage group switching control phase, the system enters the operating mode, and the DC bus voltage remains constant at 10kV. The PLC main controller reads the target parameters set by the user and collects sensor data from each module, executing three independent PID closed-loop controls: In the control loop of the preheating module 400, the PLC reads the real-time water temperature collected by the temperature sensor TT-01 located at the outlet of the preheating module 400. The first PID controller calculates the deviation between the feedwater temperature and the target saturated water temperature, outputs the total power demand of the preheating module 400, and the PLC converts the power demand into the number of heating rod groups N1 to be connected. It controls the first high-voltage switch group corresponding to the preheating module 400 in the high-voltage electrical control unit 200 to operate, adjusting the number of electric heating rod groups 702 in the preheating module 400 in a stepwise manner to match the feedwater heating demand; In the control loop of the evaporation module 500, the PLC reads the real-time steam temperature collected by the pressure sensor PT-01 located on the evaporation module 500. The pressure is calculated by the second PID controller, which calculates the deviation between the real-time pressure and the target pressure (e.g., 1.6 MPa) and outputs the power adjustment amount for the evaporation module 500. The PLC calculates the number of heating rod groups N2 that need to be turned on and controls the second high-pressure switch group of the corresponding evaporation module 500 to change the heating power in the evaporation module 500 and maintain the stable steam production pressure of the system. In the control loop of the superheated module 600, the PLC reads the superheated steam temperature collected by the temperature sensor TT-02 located at the outlet of the superheated module 600. The third PID controller calculates the deviation between the outlet temperature and the target superheated temperature (e.g., 300℃) and outputs the power requirement of the superheated module 600. The PLC calculates the number of heating rod groups N3 that need to be turned on and controls the third high-pressure switch group of the corresponding superheated module 600 to adjust the heating power of the superheated module 600 and ensure that the superheat of the output steam is constant.

[0058] S13: Operation Protection and Feedback Phase: During the above control process, the system performs real-time protection and feedback: The leakage current sensor and arc monitoring module in the high-voltage electrical control unit 200 monitor all closed high-voltage circuits in real time. Once the leakage current or arc signal exceeds the safety threshold, the PLC immediately triggers the emergency cut-off (ESD) logic, disconnects the vacuum circuit breaker in the unit 200, and cuts off the main power supply. During normal operation, the process data of TT-01, PT-01, TT-02 and the inlet flow meter FT-01 are continuously fed back to the PLC input terminal to dynamically refresh the number of heating rod access groups for the next control cycle (e.g., 10ms), forming a complete closed-loop control.

[0059] Example 5, such as Figure 1 , Figure 7a , Figure 7c , Figure 7d , Figure 7e and Figure 8b As shown, this embodiment is applied to a scenario where the high-voltage electrical control unit 200 is electrically connected in series with the preheating module 400, the evaporation module 500, and the superheating module 600. The method is executed by the PLC main controller within the high-voltage electrical control unit 200 and specifically includes the following five stages: S21: Full-dimensional data acquisition. After system startup and completion of initialization self-test, it enters a cyclic control cycle (e.g., 10ms). The PLC main controller performs data acquisition through the high-speed I / O interface: reading the current transformer data in the high-voltage electrical control unit 200 to obtain the total current of the series circuit. Read the voltage divider sensor data at both ends of modules R1, R2, and R3 to obtain the voltage at each stage. ); Read the data from the pressure sensor PT-01 and temperature sensor TT-02 at the system outlet. ); Read the target mode (hot water / saturated / superheated steam) and target parameters set by the user on the host computer. ).

[0060] S22: Real-time impedance identification and safety clamping. To prevent breakdown caused by excessive voltage in a module stage due to impedance imbalance in a series circuit, the PLC performs real-time safety calculations: based on Ohm's law, it calculates the real-time impedance of each module using the collected voltage and current. And so on; if any level impedance R exceeds the preset threshold (approaching infinity), the PLC determines it as a "circuit open circuit" and immediately triggers the shutdown protection to cut off the main circuit; calculate the voltage distribution coefficient. That is, the proportion of the maximum impedance module in the total impedance: The maximum total voltage that the reverse propulsion system is allowed to apply. : in This is the rated withstand voltage value for a single-stage module. The value will be passed as a threshold to subsequent control steps.

[0061] S23: Dual closed-loop decoupling operation, based on steam pressure deviation ( ), output voltage regulation command through PID calculation ( This voltage regulation command represents the total input voltage required to maintain the pressure; based on the outlet temperature deviation ( The frequency command of the variable frequency high-pressure water pump set 303 is output through PID calculation. Adjust the water supply flow rate to match the heating power.

[0062] S24: Multimodal logic execution. Based on the user-defined target mode, the PLC automatically configures the system's flow channels and electrical topology: In hot water mode, the PLC outputs a command to open the hot water switching valve V1 and simultaneously closes the bypass switches K2 and K3 connected in parallel with the evaporation module 500 and the superheating module 600, so that current flows only through the preheating module 400; In saturated steam mode, the PLC outputs a command to open the saturated steam switching valve V2 and close the bypass switch K3 connected in parallel with the superheating module 600, so that the preheating module 400 and the evaporation module 500 work in series; In superheated steam mode, the PLC outputs a command to open the main steam valve V3 and disconnect all bypass switches, so that the preheating module 400, the evaporation module 500, and the superheating module 600 all operate in series, achieving maximum energy efficiency.

[0063] S25: Hardware drive and arbitration. Before outputting the final control signal, the PLC performs a critical safety arbitration: voltage command arbitration, which converts the voltage demand calculated by the PID controller into a voltage requirement. ) and the safe voltage calculated in step S22 ( The two values ​​are compared, and the smaller value is taken as the final target voltage. This ensures that even if the PID controller requests full-power heating, the output voltage will be limited to a safe range as long as there is a risk of impedance imbalance in the system; the drive execution will be arbitrated. The signal is sent to the SCR power controller group within the high-voltage electrical control unit 200 to adjust the DC bus voltage. The frequency converter sent to the variable frequency high-pressure water pump set 303 controls the operation of valves V1 / V2 / V3 and bypass switch to complete the control task of this cycle.

[0064] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A modular heat transfer medium electric steam boiler system, characterized in that, It includes a high-voltage electrical control unit (200), a high-voltage water supply unit (300), and a preheating module (400), an evaporation module (500), and a superheating module (600) that are connected in sequence along the flow direction of the working fluid. The high-voltage electrical control unit (200) includes a rectifier (2), a filter and protection circuit (3), a DC bus capacitor (5), and multiple power controllers (4) connected in sequence. The output terminals of the multiple power controllers (4) are respectively connected to the preheating module (400), the evaporation module (500), and the superheating module (600). The preheating module (400), the evaporation module (500), and the superheating module (600) all use a pressure-bearing cylinder as the outer shell. Several dry heating sleeves (701) are suspended in the pressure-bearing cylinder along the axial direction. The dry heating sleeves (701) are used to heat the working fluid.

2. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, The system adopts an integrated skid-mounted layout. The high-pressure water supply unit (300), preheating module (400), evaporation module (500) and superheating module (600) are all installed through skid-mounted base (100). The high-pressure water supply unit (300) includes a filter device (301), a water storage tank (302) and a variable frequency high-pressure water pump group (303) in sequence along the working fluid flow direction. The system also includes a steam-water separator (900), whose input end is connected to the steam collection port of the evaporation module (500) and whose output end is connected to the input end of the superheating module (600). The preheating module (400), evaporation module (500) and superheating module (600) all adopt a pressure-bearing cylinder structure. The dry heating sleeve (701) is a blind tube structure with one end open and the other end closed. The open end of the dry heating sleeve (701) is sealed and fixed to the tube sheet at the end of the cylinder, and the closed end extends into the inside of the cylinder and has a gap with the inner wall of the cylinder. A working fluid heat exchange channel for water or steam is formed between the inner wall of the pressure-bearing cylinder and the outer wall of the dry heating sleeve (701).

3. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, Several electric heating rods (702) connected in parallel or in series are inserted into the inner hole of the dry heating sleeve (701). The gap between the dry heating sleeve (701) and the electric heating rods (702) is filled with a high-efficiency heat-conducting medium (703). The heat generated by the electric heating rods (702) is transferred to the dry heating sleeve (701) through the high-efficiency heat-conducting medium (703).

4. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, The outer wall of the heating section of the electric heating rod assembly (702) is directly immersed in the high-efficiency heat-conducting medium (703), and the dry heating sleeve (701) constitutes the sealed cavity of the high-efficiency heat-conducting medium (703); The high-efficiency heat transfer medium heat exchange assembly (700) also includes an inner isolation sleeve; the inner isolation sleeve is sleeved on the outside of the electric heating rod assembly (702) and located inside the dry heating sleeve (701); the high-efficiency heat transfer medium (703) fills the interlayer space formed between the outer wall of the inner isolation sleeve and the inner wall of the dry heating sleeve (701); the electric heating rod assembly (702) conducts heat in contact with the inner wall of the inner isolation sleeve or conducts heat through solid heat transfer filler.

5. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, The dry heating jacket (701) has a connecting neck (704) at its open end, and a visual fully sealed expansion compensation device (800) is vertically connected to the top of the connecting neck (704). The visual fully sealed expansion compensation device (800) includes a metal bellows (801), a fully sealed top cover (802), a liquid level indicator rod (803), and a visual protective shell (804). The lower end of the metal bellows (801) is sealed to the connecting neck (704). The fully sealed top cover (802) is sealed and fixed to the upper end of the metal bellows (801). The liquid level indicator rod (803) is vertically fixed to the center of the fully sealed top cover (802). The visual protective shell (804) is covered on the outside and has a longitudinal observation window.

6. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, The working fluid heat exchange channel inside the preheating module (400) is provided with a spiral enhanced heat transfer structure; the spiral enhanced heat transfer structure includes a spiral baffle (402) sleeved on the outer periphery of the dry heating sleeve (701); the outer wall of the dry heating sleeve (701) inside the superheating module (600) is provided with a gas phase enhanced heat transfer structure, the gas phase enhanced heat transfer structure includes longitudinal heat dissipation fins (602) extending along the axial direction of the dry heating sleeve (701).

7. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, The working fluid heat exchange channel inside the evaporation module (500) is provided with a vapor-liquid separation guide structure; the vapor-liquid separation guide structure includes a number of notched guide plates (502) distributed axially between the dry heating sleeves (701); the notched guide plate (502) is a circular plate, with a horizontal exhaust notch (5021) cut off at the top to form a top vapor phase channel for rapid steam discharge, and a water passage hole (5022) opened at the bottom for liquid water to flow through.

8. The modular heat-conducting medium electric steam boiler system according to claim 1, characterized in that, It also includes a phase change auxiliary unit and a thermal expansion compensation pipeline; the phase change auxiliary unit includes a steam-water separator installed between the evaporation module and the superheated module and a steam buffer tank located at the end of the system. The top outlet of the evaporation module is connected to the inlet of the steam-water separator via a pipeline, and the dry steam outlet of the steam-water separator is connected to the inlet of the superheated module. Ω-shaped or U-shaped stress compensation bends are provided on the connecting pipelines between the evaporation module (R2) and the steam-water separator, and between the superheated module (R3) and the steam buffer tank.

9. The intelligent control method for the modular heat transfer medium electric steam boiler system as described in any one of claims 1-8, characterized in that, Includes the following steps: Monitor the input voltage amplitude at the front end of the high-voltage electrical control unit (200); When the input voltage amplitude is within the first preset range, the intelligent high-voltage topology switching matrix is ​​controlled to reconstruct the preheating module (400), evaporation module (500) and superheating module (600) into an electrical parallel topology, and the first control strategy is executed; When the input voltage amplitude is within the second preset range, the intelligent high-voltage topology switching matrix is ​​controlled to reconstruct the preheating module (400), evaporation module (500) and superheating module (600) into an electrical series topology, and the second control strategy is executed; Wherein, the maximum value of the first preset range is less than or equal to the minimum value of the second preset range.

10. The intelligent control method according to claim 9, characterized in that: The first control strategy includes: Load group integrity self-test steps: Before connecting the main power supply, inject diagnostic pulses into the electric heating rod group (702) in each module, determine the insulation impedance and connection status of each group based on the response current, and lock the faulty group; Constant pressure group switching control steps: Under the condition of constant DC bus voltage, based on the deviation between the outlet temperature of the preheating module (400), the steam pressure inside the evaporation module (500) or the outlet temperature of the superheating module (600) and their respective target values, the power demand of each module is calculated by PID control, and the number of electric heating rod groups (702) put into operation is independently controlled in a step manner. The second control strategy includes: Real-time impedance identification and safety clamping steps: Collect the total current of the series circuit and the voltage drop across each module, and calculate the real-time impedance of each module; calculate the voltage distribution coefficient based on the real-time impedance of each module, and deduce the maximum safe total voltage that the system can apply; Dynamic pressure balance control steps: Decoupling calculations are performed based on steam pressure deviation and outlet temperature deviation, and voltage regulation commands and water pump flow regulation commands are output respectively. The voltage regulation commands are arbitrated with the maximum safe total voltage as the limit, and the final target voltage is output.

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