Steam heat exchange system based on negative pressure regulation

Abstract

A kind of steam heat exchange system based on negative pressure regulation, by steam pressure reducing valve, pressure sensor, steam regulating valve, heat exchange equipment, storage tank, negative pressure pump and vacuum pump etc..Industrial steam is initially depressurized by pressure reducing valve, and steam regulating valve dynamically adjusts steam flow according to the real-time feedback signal of pressure sensor, heat exchange equipment is connected with storage tank with pressure sensor and vacuum pump through pipeline, and pneumatic valve on vacuum pump pipeline is switched according to the real-time feedback signal of pressure sensor on storage tank, to establish and maintain stable negative pressure environment in the system, utilize the corresponding relationship between saturated steam pressure and temperature, realize accurate control of steam temperature in the range of 40-100 ℃, efficiently utilize latent heat of steam, energy-saving benefit is remarkable, and scene adaptability is good.

Description

Technical Field

[0001] This utility model relates to the field of steam heat energy exchange technology, and in particular to a steam heat exchange system based on negative pressure environment regulation and pressure-temperature dynamic coupling regulation, which realizes dynamic high-precision regulation of steam temperature and meets the combined needs of efficient heating, precise temperature control and energy saving in continuous production scenarios. Background Technology

[0002] Existing steam heating and heat exchange systems typically employ direct steam heating or hot water unit solutions. While these can accomplish basic heating tasks, they still have significant shortcomings in practical industrial applications:

[0003] (1) Insufficient temperature control accuracy: Traditional steam heat exchange systems mostly rely on simple open-loop control of steam pressure reducing valves and steam regulating valves, or closed-loop regulation based on fixed parameters of PID. Due to the dynamic nonlinear mapping relationship between steam pressure and temperature, and the significant thermal inertia of the system (such as the heat capacity hysteresis effect of the heat exchanger), there is a significant delay and overshoot in temperature control. Even with PID control, it is difficult to compensate for the influence of factors such as steam flow fluctuations and material property changes on temperature in real time. In practical applications, the temperature error often exceeds ±5℃, causing heat-sensitive materials (such as active proteins in biological agents and heat-sensitive nutrients in food raw materials) to denature and fail due to local overheating, or to generate heating blind spots, resulting in unstable batch quality of products.

[0004] (2) Low energy efficiency: Existing steam heat exchange systems generally lack active management of condensate during the condensation stage, often employing passive steam traps or timed discharge methods. This leads to condensate accumulation due to poor gravity discharge, forming liquid film thermal resistance and significantly reducing the heat exchange efficiency between steam and the heat exchange medium. Simultaneously, existing systems use fixed pressure or flow control strategies during the latent heat release process, failing to dynamically adjust steam state parameters (such as pressure and flow rate) according to changes in material heat load. This results in a large amount of waste heat being directly discharged as high-temperature condensate or flash steam, with the overall system thermal efficiency typically below 70%, leading to high system operating costs. To address these issues, this invention proposes a novel steam heat exchange system: by introducing a differential pressure level gauge to monitor the condensate tank level in real time, and combining it with a PID closed-loop control strategy to drive an automatic regulating valve, dynamic and precise condensate discharge is achieved, effectively eliminating liquid film thermal resistance. Simultaneously, a dynamic coupling control model of steam pressure and flow rate based on material heat load prediction is constructed, and the steam state parameters (pressure and flow rate) are optimized in real time using a fuzzy PID algorithm, dynamically matching the latent heat release process with the material's heat absorption demand. The above solution improves the overall thermal efficiency of the system to over 90%, saves more than 20% energy compared to traditional systems, and significantly reduces operating costs.

[0005] (3) Significant safety hazards: Traditional steam heat exchange systems suffer from severe temperature fluctuations due to insufficient temperature control accuracy (instantaneous temperature difference can reach 10-15℃), which can easily lead to product quality risks (such as inactivation of active ingredients in biological agents, denaturation of nutritional components in food raw materials, resulting in a decrease in the pass rate of batch products). Furthermore, temperature runaway may trigger a chain reaction, causing thermal stress fatigue damage to equipment (such as cracking of heat exchanger welds, thermal deformation of pipelines) or extreme accidents such as decomposition and explosion of heat-sensitive materials (such as solvent-containing chemicals). Meanwhile, the existing system relies heavily on manual experience for adjustment (such as manually adjusting valve opening and offline PID parameter tuning), which has inherent defects such as adjustment lag (response time ≥30s), temperature overshoot (overshoot amplitude ≥8℃) and human error (such as incorrect parameter settings and untimely emergency response). In particular, it is difficult to achieve precise safety intervention under sudden working conditions (such as sudden rise in steam pressure and sudden change in material flow). It cannot meet the core requirements of "process controllability" and "risk prevention" in high-standard safety production specifications such as GMP / ISO 45001, resulting in the long-term existence of major safety hazards such as personnel burns, equipment damage and production interruption.

[0006] (4) Poor adaptability of the control mechanism: Most existing steam heat exchange systems adopt a static PID control mode based on a single variable (such as steam pressure or flow rate), which lacks the ability to dynamically couple and control steam pressure, flow rate and negative pressure of heat exchange equipment (such as vacuum). When the material properties (such as viscosity, specific heat capacity) change dynamically in industrial scenarios, or when process parameters (such as temperature setpoint, production load) fluctuate significantly, the system suffers from response lag (adjustment delay ≥20s), parameter overshoot (pressure / flow rate fluctuation amplitude ≥15%), and heat load matching error (deviation between heat absorption demand and latent heat release of steam ≥20%) due to the lack of decoupling control. This leads to product quality fluctuations (such as batch-to-batch temperature difference ≥5℃), increased energy consumption (steam waste rate ≥10%), and accumulation of thermal stress in equipment. In addition, traditional control strategies cannot achieve feedforward-feedback composite control of steam pressure-flow rate-negative pressure, which is difficult to meet the stringent requirements of dynamic thermal balance for high-precision processes such as fine chemicals and food processing.

[0007] Therefore, there is an urgent need to develop a steam heat exchange system with precise temperature control capabilities (temperature control accuracy ≤ ±1℃) and high thermal energy utilization (thermal energy utilization rate ≥ 90%). Through multivariable dynamic decoupling control technology, the system can achieve real-time coordinated regulation of steam pressure, flow rate and heat exchange medium temperature, ensuring that the system can still achieve second-level dynamic response (adjustment delay ≤ 5s) under complex operating conditions such as sudden changes in material properties (e.g., viscosity fluctuation ±50%) and sudden changes in process parameters (load increase / decrease ≥ 30%), thus achieving the dual goals of energy saving and safe production. Summary of the Invention

[0008] The purpose of this invention is to provide a steam heat exchange system based on negative pressure regulation, to solve the problems of low temperature control accuracy, high energy consumption, and poor safety in existing technologies. To achieve the above objective, this invention adopts the following technical solution:

[0009] A steam heat exchange system based on negative pressure regulation includes a steam supply module, a heat exchange device, and a condensate discharge module connected in sequence, as well as a negative pressure control module connected to the heat exchange device and the condensate discharge module. The steam supply module includes an industrial steam input pipe, a shut-off valve, a Y-type filter, a steam pressure reducing valve, and a steam regulating valve connected in series. A thermometer and a first pressure gauge are installed on the steam connection pipe between the Y-type filter and the steam pressure reducing valve, and a second pressure gauge is installed on the steam connection pipe between the steam pressure reducing valve and the steam regulating valve. The output end of the steam regulating valve is connected to the input end of the heat exchange device via a steam pipe, and a pressure sensor is installed on the output steam pipe of the steam regulating valve. The first and second pressure gauges measure the steam pressure before and after the steam pressure reducing valve, respectively, to ensure that the steam pressure stabilizes within a set range after the steam pressure reducing valve initially reduces the steam pressure. The pressure sensor monitors the pressure in real time. The steam regulating valve measures the output steam pressure and provides a feedback signal. Based on the feedback signal from the pressure sensor, the steam regulating valve dynamically adjusts its opening to maintain its set output steam pressure for the heat exchange equipment, forming a steam heat exchange chamber. The condensate discharge module includes a storage tank, a pneumatic valve, and a negative pressure pump connected in sequence. A differential pressure level gauge is installed on the storage tank, which monitors the condensate level in the tank in real time and controls the pneumatic valve and negative pressure pump to start synchronously to extract and discharge the condensate. The negative pressure control module includes a vacuum pump, a first negative pressure pneumatic valve, a second negative pressure pneumatic valve, and a negative pressure sensor. The heat exchange equipment and the storage tank are connected via the first negative pressure pneumatic valve. The vacuum pump is connected to the upper part of the storage tank via the second negative pressure pneumatic valve. During the heat exchange process, the heat exchange equipment is evacuated through the storage tank. The negative pressure sensor is installed inside the storage tank, and the negative pressure transmitter monitors the negative pressure inside the heat exchange equipment and provides feedback to control the opening and closing of the second negative pressure pneumatic valve.

[0010] The steam heat exchange system based on negative pressure regulation of this utility model achieves precise control of steam temperature through the following control mechanism: a steam pressure reducing valve initially reduces the steam pressure; a pressure sensor monitors the downstream pressure of the steam regulating valve in real time and provides feedback; the steam regulating valve dynamically adjusts its opening according to the feedback signal to maintain the set pressure; a vacuum pump runs continuously; a negative pressure sensor monitors the negative pressure status of the heat exchange equipment; and a second negative pressure pneumatic valve adjusts the negative pressure. Utilizing the correlation between saturated steam pressure and temperature, precise control of the steam temperature is achieved within the range of 40-100℃. The steam pressure reducing valve is used to reduce the steam pressure to a preset range to ensure that the reduced steam pressure falls within the rated regulation range of the steam regulating valve, thereby ensuring the precise control capability of the steam regulating valve.

[0011] In the above technical solution, the steam regulating valve dynamically adjusts its opening degree according to the feedback signal of the pressure sensor. Its control system includes a pressure sensor, a signal processing unit, and an actuator. The pressure sensor detects the steam pressure downstream of the steam regulating valve in real time and transmits the detection signal to the signal processing unit. The signal processing unit compares the detection signal with a preset pressure threshold and generates a control command. The actuator dynamically adjusts the opening degree of the steam regulating valve according to the control command to maintain the set pressure.

[0012] In the above technical solution, the system further includes a temperature monitoring unit and an alarm module; the temperature monitoring unit is installed inside the heat exchange equipment and is used to detect the material temperature in real time; the alarm module is signal-connected to the temperature monitoring unit, and when the detected temperature exceeds a preset threshold, the alarm module is triggered to issue an alarm signal.

[0013] In the above technical solution, the system further includes a data recording unit, which is connected to the pressure sensor, negative pressure sensor, and thermometer signal to collect and store dynamic data of pressure and temperature changes over time during system operation in real time.

[0014] In the above technical solution, the system also includes a human-machine interface. The human-machine interface is connected to the control system of the pressure sensor, negative pressure sensor, steam regulating valve and vacuum pump through electrical signals and / or wireless communication. It is used to display the internal temperature monitoring data and negative pressure parameters of the system in real time, and supports users to manually adjust the opening of the steam pressure reducing valve, set the pressure threshold or negative pressure target value by inputting commands through the interface.

[0015] The beneficial effects of this utility model are:

[0016] This invention creates a negative pressure environment in the heat exchange equipment and combines the synergistic mechanism of a steam pressure reducing device, a flow regulating device, and a negative pressure regulating device. Based on the correlation between saturated steam pressure and temperature, it achieves dynamic and high-precision control of steam temperature by dynamically adjusting steam pressure and negative pressure. Its core technology breaks through the limitations of traditional steam heat exchange systems that rely on single pressure or temperature control. It solves the problems of temperature response lag and insufficient control precision through multi-variable coupled control, thereby meeting the combined needs of efficient heating, precise temperature control, and energy saving in continuous production scenarios of temperature-sensitive materials such as pharmaceuticals, food processing, and fine chemicals.

[0017] This utility model is applicable to heating scenarios for heat-sensitive materials through the following technical features:

[0018] The precise steam temperature control mechanism ensures that the material heating temperature deviation is ≤±1℃;

[0019] A negative pressure environment reduces the steam condensation rate and makes full use of the latent heat of steam.

[0020] The linkage mechanism between the temperature monitoring unit and the alarm module prevents the material from overheating;

[0021] The condensate drainage module has an automatic drainage function to prevent condensate buildup from affecting heat exchange efficiency; the combined effect of these technical features enables safe heating of heat-sensitive materials and reduces energy consumption.

[0022] Precise temperature control: Achieves a temperature control accuracy of ±1℃ through negative pressure environment and pressure-temperature coupling regulation;

[0023] High efficiency and energy saving: Maximizes the utilization of latent heat of steam, reducing energy consumption by 20%-30%;

[0024] High safety: Avoids high-temperature damage to materials, improving system operational stability;

[0025] Wide applicability: Suitable for temperature-sensitive industrial scenarios such as pharmaceuticals, food, and chemicals. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a steam heat exchange system based on negative pressure regulation proposed in this utility model.

[0027] In the diagram: 1-Stop valve, 2-Y-type filter, 3-Thermometer, 4-First pressure gauge, 5-Steam pressure reducing valve, 6-Second pressure gauge, 7-Steam regulating valve, 8-Pressure sensor, 9-Heat exchange equipment, 10-First negative pressure pneumatic valve, 11-Storage tank, 12-Negative pressure sensor, 13-Second negative pressure pneumatic valve, 14-Vacuum pump, 15-Differential pressure level gauge, 16-Pneumatic valve, 17-Negative pressure pump. Detailed Implementation

[0028] The specific 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.

[0029] Reference Figure 1 The steam heat exchange system consists of a steam supply module, heat exchange equipment, a negative pressure control module, and a condensate discharge module. The specific connection relationships and configurations are as follows:

[0030] Steam supply module: The following components are connected in series: shut-off valve 1, Y-type filter 2, thermometer 3, first pressure gauge 4, steam pressure reducing valve 5, second pressure gauge 6, pressure sensor 8, and their interlocked steam regulating valve 7. Functions of each component: Shut-off valve 1 is used for system opening and closing control; Y-type filter 2 filters impurities in the steam to prevent blockage of subsequent valves; thermometer 3 monitors the steam inlet temperature; first pressure gauge 4 and second pressure gauge 6 measure the steam pressure before and after the pressure reducing valve, respectively; steam pressure reducing valve 5 performs initial pressure reduction to ensure the steam pressure remains stable within the set range; pressure sensor 8 monitors the downstream pressure of steam regulating valve 7 in real time and feeds back the signal to the control system.

[0031] Heat exchanger 9: Connected to steam regulating valve 7, its internal design forms a steam heat exchange chamber for heat exchange with the medium to be heated (such as water or other fluids).

[0032] Negative pressure control module: includes vacuum pump 14, first negative pressure pneumatic valve 10, second negative pressure pneumatic valve 13, storage tank 11 and negative pressure sensor 12; vacuum pump 14 is connected to heat exchange equipment 9 through first negative pressure pneumatic valve 10 and second negative pressure pneumatic valve 13 to form a negative pressure circuit; negative pressure sensor 12 is installed on heat exchange equipment to monitor the negative pressure status in real time; storage tank 11 is used to collect or buffer condensate and is equipped with a liquid level monitoring device.

[0033] Condensate discharge module: including storage tank 11, differential pressure level gauge 15, pneumatic valve 16 and negative pressure pump 17, characterized in that: after steam condenses, it is stored in storage tank 11, and differential pressure level gauge 15 monitors the liquid level of condensate in storage tank in real time; when the liquid level reaches a preset threshold, the system triggers a linkage control mechanism, and pneumatic valve 16 and negative pressure pump 17 start synchronously, and discharge condensate from storage tank 11 through negative pressure extraction to maintain the dynamic balance of liquid level in storage tank.

[0034] Control logic and operation process:

[0035] The system achieves precise control of steam temperature (40-100℃ range) through the following control logic:

[0036] A. Steam pressure regulation process

[0037] Preliminary pressure reduction: Steam enters the system through shut-off valve 1 and is reduced to a preset pressure, such as 0.3-0.45 MPa, through steam pressure reducing valve 5. The first pressure gauge 4 and the second pressure gauge 6 display the pressure changes in real time.

[0038] Dynamic pressure control: Pressure sensor 8 monitors the downstream pressure of steam regulating valve 7. When the pressure deviates from the set value, it sends a feedback signal to the control system. The control system adjusts the opening of steam regulating valve 7 through a PID algorithm: if the downstream pressure increases, the valve opening is reduced to decrease the steam flow; if the pressure decreases, the opening is increased to increase the flow, thereby maintaining the set pressure, for example, with an accuracy of ±0.02MPa.

[0039] B. Negative Pressure Regulation and Temperature Control Process

[0040] Negative pressure establishment and maintenance: Start vacuum pump 14 to draw air from heat exchange equipment 9 through first negative pressure pneumatic valve 10 to form a negative pressure environment; negative pressure sensor 12 monitors pressure in real time.

[0041] Temperature-related control: Based on the relationship between saturated vapor pressure and temperature, temperature control is achieved by adjusting the negative pressure. When the target temperature needs to be reduced, the control system instructs the second negative pressure pneumatic valve 13 to partially open and increase the negative pressure; conversely, the second negative pressure pneumatic valve 13 is closed to reduce the negative pressure, thereby maintaining a stable steam temperature.

[0042] Dynamic adjustment mechanism: If the negative pressure sensor 12 detects that the negative pressure deviates from the set value, the control system automatically adjusts the opening of the second negative pressure pneumatic valve 13: when the negative pressure is too high, the opening is reduced to limit the amount of air pumped; when the negative pressure is insufficient, the opening is increased to enhance the air pumping and ensure that the temperature is controlled within the target range.

[0043] A control method for a steam heat exchange system based on negative pressure regulation includes the following steps:

[0044] S1. After the industrial steam is initially depressurized by the pressure reducing valve, the steam flow rate is dynamically adjusted by the steam regulating valve according to the feedback signal from the pressure sensor before entering the heat exchange equipment.

[0045] S2. The vacuum pump is controlled by interlocking pneumatic valves to establish and maintain a negative pressure environment;

[0046] S3. Since there is a corresponding relationship between saturated vapor pressure and temperature, the steam temperature can be precisely adjusted within the range of 40-100℃ by precisely controlling the negative pressure value.

[0047] S4. Storage tanks equipped with pressure sensors monitor condensate pressure and level in real time, and use negative pressure pumps to discharge condensate, with a thermal energy utilization rate of ≥90%;

[0048] S5, the tank pressure sensor and pneumatic valve form a closed-loop control to further stabilize the system pressure.

[0049] Among them, the pressure reducing valve is a pilot-operated steam pressure reducing valve, which initially reduces the pressure of industrial steam to ensure that the pressure of the reduced steam falls into the rated regulation range of the steam regulating valve, thereby ensuring the precise regulation capability of the steam regulating valve.

[0050] The pneumatic regulating valve adopts a diaphragm actuator, which accepts a 4-20mA analog signal to control the opening degree, thereby achieving precise regulation of steam flow.

[0051] The vacuum pump is controlled by the interlock between the pressure-vacuum linkage control system and the pneumatic valve. It establishes and maintains a negative pressure environment. When the pressure sensor detects that the pressure exceeds the set negative pressure value, the vacuum pump is triggered to start. When the pressure is lower than the set threshold, the vacuum pump automatically stops to avoid over-vacuuming.

[0052] The steam heat exchange system based on negative pressure regulation in this invention achieves a temperature control accuracy of ±1℃ through negative pressure environment and pressure-temperature coupling regulation; maximizes the utilization of latent heat of steam, reducing energy consumption by 20%-30%; avoids high-temperature damage to materials, and improves system operation stability; and is suitable for temperature-sensitive industrial scenarios such as pharmaceuticals, food, and chemicals.

[0053] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A steam heat exchange system based on negative pressure regulation, characterized in that: The system includes a steam supply module, a heat exchange device, and a condensate discharge module connected in sequence, as well as a negative pressure control module connected to the heat exchange device and the condensate discharge module. The steam supply module includes an industrial steam input pipe, a shut-off valve, a Y-type filter, a steam pressure reducing valve, and a steam regulating valve connected in series. A thermometer and a first pressure gauge are installed on the steam connection pipe between the Y-type filter and the steam pressure reducing valve, and a second pressure gauge is installed on the steam connection pipe between the steam pressure reducing valve and the steam regulating valve. The output end of the steam regulating valve is connected to the input end of the heat exchange device via a steam pipe, and a pressure sensor is installed on the output steam pipe of the steam regulating valve. The first and second pressure gauges measure the steam pressure before and after the steam pressure reducing valve, respectively, to ensure that the steam pressure stabilizes within a set range after the steam pressure reducing valve initially reduces the steam pressure. The pressure sensor monitors the output of the steam regulating valve in real time. The steam pressure sensor provides a feedback signal, and the steam regulating valve dynamically adjusts its opening based on the feedback signal to maintain its set output steam pressure for the heat exchange equipment, forming a steam heat exchange chamber. The condensate discharge module includes a storage tank, a pneumatic valve, and a negative pressure pump connected in sequence. A differential pressure level gauge is installed on the storage tank, which monitors the condensate level in the tank in real time and controls the pneumatic valve and the negative pressure pump to start synchronously to extract and discharge the condensate. The negative pressure control module includes a vacuum pump, a first negative pressure pneumatic valve, a second negative pressure pneumatic valve, and a negative pressure sensor. The heat exchange equipment and the storage tank are connected through the first negative pressure pneumatic valve. The vacuum pump is connected to the upper part of the storage tank through the second negative pressure pneumatic valve. During the heat exchange process, the heat exchange equipment is evacuated through the storage tank. The negative pressure sensor is installed inside the storage tank, and the negative pressure transmitter monitors the negative pressure inside the heat exchange equipment and provides feedback to control the opening and closing of the second negative pressure pneumatic valve.

2. The steam heat exchange system based on negative pressure regulation according to claim 1, characterized in that: The steam regulating valve dynamically adjusts its opening degree according to the feedback signal from the pressure sensor. Its control system includes a pressure sensor, a signal processing unit, and an actuator. The pressure sensor detects the steam pressure downstream of the steam regulating valve in real time and transmits the detection signal to the signal processing unit. The signal processing unit compares the detection signal with a preset pressure threshold and generates a control command. The actuator dynamically adjusts the opening degree of the steam regulating valve according to the control command to maintain the set pressure.

3. The steam heat exchange system based on negative pressure regulation according to claim 1, characterized in that: The system also includes a temperature monitoring unit and an alarm module; the temperature monitoring unit is installed inside the heat exchange equipment and is used to detect the material temperature in real time; the alarm module is connected to the temperature monitoring unit and is triggered to issue an alarm signal when the detected temperature exceeds a preset threshold.

4. The steam heat exchange system based on negative pressure regulation according to claim 1, characterized in that: The system also includes a data recording unit, which is connected to the pressure sensor, negative pressure sensor, and thermometer signal to collect and store dynamic data of pressure and temperature changes over time during system operation in real time.

5. The steam heat exchange system based on negative pressure regulation according to claim 1, characterized in that: The system also includes a human-machine interface, which is connected to the control system of the pressure sensor, negative pressure sensor, steam regulating valve and vacuum pump via electrical signals and / or wireless communication. The human-machine interface is used to display the internal temperature monitoring data and negative pressure parameters in real time, and supports users to manually adjust the opening of the steam pressure reducing valve and set the pressure threshold or negative pressure target value by inputting commands through the interface.

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