Waste heat four-stage gradient utilization network system

Abstract

The invention relates to the technical field of industrial volatile organic compound treatment, in particular to a waste heat four-stage gradient utilization network system which comprises four stages of waste heat utilization paths, and the four stages of waste heat utilization paths are as follows in sequence: first-stage utilization: RTO exhaust smoke preheats runner desorption wind to 200 DEG C through a plate-fin heat exchanger; secondary utilization: preheating the desorbed waste gas to 150 DEG C through a heat pipe heat exchanger; third-stage utilization: the waste heat at 80 DEG C drives an absorption heat pump system; in the fourth-stage utilization, 50 DEG C low-temperature waste heat is used for workshop heating through a finned tube radiator; according to the plate-fin heat exchanger and heat pipe combined heat exchange device, the waste heat utilization rate is increased to 72% from 35%. By constructing a four-stage waste heat utilization path, low-temperature waste heat generated when RTO smoke is exhausted to 50 DEG C is gradually converted into desorption air preheating, air inlet preheating, heat pump driving, workshop heating and other energy consumption requirements, the problems that traditional waste heat utilization efficiency is low, equipment cooperation is poor, regulation and control are not flexible and the like are effectively solved, and an innovative scheme is provided for efficient utilization of industrial waste heat.

Description

Technical Field

[0001] This invention relates to the field of industrial volatile organic compound (VOCs) treatment technology, and in particular to a four-stage waste heat utilization network system. Background Technology

[0002] In traditional rotary turbine + RTO systems, the flue gas temperature of the RTO can reach 300-400℃, but the waste heat utilization rate is only about 35%, and a large amount of heat energy is directly emitted in the form of flue gas, resulting in energy waste.

[0003] The existing technology has the following drawbacks: 1. Low waste heat utilization efficiency and serious energy waste. Traditional waste heat recovery systems mostly employ single-stage or simple series heat exchange methods, which can only utilize a portion of high-grade waste heat. Low-grade waste heat (below 100℃) is directly emitted due to a lack of suitable technology. According to statistics, the waste heat utilization rate of organic waste gas treatment equipment (such as RTO) in the industrial sector is generally less than 35%, and a large amount of medium and low temperature waste heat below 300℃ is wasted, resulting in increased energy consumption and carbon emissions.

[0004] 2. Equipment is distributed in a scattered manner, resulting in poor system coordination. In existing systems, components such as heat exchangers, heat pumps, and heating equipment operate independently, lacking systematic planning of heat exchange paths. For example, the heat exchange between desorbed waste gas and intake air, and the distribution of waste heat from the heat pump drive source and workshop heating, all rely on manual control, resulting in low heat exchange efficiency, high energy consumption, and difficulty in adapting to fluctuations in operating conditions.

[0005] 3. Lacks dynamic control capabilities and insufficient operational flexibility. Traditional systems rely on fixed parameter control and cannot dynamically optimize the heat exchange process based on variables such as waste gas concentration and production load. When VOCs concentration changes, heat recovery equipment is prone to overheating or inefficient operation, resulting in redundant desorption air volume and energy consumption. According to industry data, the energy waste rate of conventional systems in the desorption process is as high as 40% or more, and it is difficult to achieve precise allocation of waste heat resources.

[0006] To address the above problems, this invention proposes a four-stage waste heat utilization network system. Summary of the Invention

[0007] The main objective of this invention is to provide a four-stage waste heat utilization network system, which can effectively solve the problems in the background art.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A waste heat four-stage cascade utilization network system includes: The four-stage waste heat utilization pathways are as follows: Primary utilization: RTO exhaust gas (300℃) is preheated to 200℃ by a plate-fin heat exchanger to remove desorbed air from the rotor; Secondary utilization: The desorption waste gas (110℃) is preheated to 150℃ by a heat pipe heat exchanger; Level 3 utilization: 80℃ waste heat drives an absorption heat pump system; Level 4 utilization: Low-temperature waste heat at 50℃ is used for workshop heating through finned tube radiators; The waste heat utilization rate of the plate heat exchanger and heat pipe combined heat exchange device has been increased from 35% to 72%. The AI ​​dynamic control platform optimizes heat exchange parameters based on a VOCs concentration prediction model.

[0009] Preferably, the primary utilization module adopts a plate-fin heat exchanger with a heat exchange area ≥80㎡, a heat exchange efficiency ≥85%, and an outlet temperature controlled at 200±5℃. It is equipped with a PID-regulated flue gas bypass valve with a bypass valve opening adjustment accuracy of ±2%.

[0010] Preferably, the secondary utilization module uses a copper-water heat pipe heat exchanger with a heat pipe diameter of 25mm, a length of 3m, a liquid filling rate of 60%, a heat exchange efficiency of ≥82%, an inlet air preheated to 150±3℃, and a heat pipe evaporation section to condensation section length ratio of 1:1.5.

[0011] Preferably, the three-stage utilization module includes an absorption heat pump unit (COP≥1.8), which uses 80℃ waste heat as a driving source to produce 40℃ cold water, with an evaporator heat exchange efficiency≥75% and a condenser outlet water temperature controlled at 65±3℃.

[0012] Preferably, the fourth-level utilization module uses a finned tube radiator with a heat dissipation area of ​​≥500㎡. It dynamically distributes 50℃ of residual heat through an electric regulating valve (accuracy ±2%) to maintain the workshop temperature at 18-22℃, and the radiator fin spacing is 3-5mm.

[0013] Preferably, in the combined plate heat exchanger and heat pipe heat exchange device: The plate heat exchanger uses 316L stainless steel plates with a corrugation angle of 60° and a heat transfer coefficient of ≥3000W / (㎡・K). The heat pipes are arranged in series with the plate heat exchanger, with an overall heat loss of <5% and a combined heat exchange efficiency of ≥90%.

[0014] Preferably, the AI ​​dynamic control platform monitors 16 temperature / pressure measurement points in real time (accuracy ±0.5℃ / ±1kPa), with a response time of <1s, and optimizes the bypass valve opening and heat pump power based on the digital twin, with a control cycle of ≤10s.

[0015] Preferably, the heat exchange efficiency of the four-stage utilization path is as follows: Level 1 ≥ 85%, Level 2 ≥ 82%, Level 3 ≥ 70%, Level 4 ≥ 65%, and the pipeline is insulated with 100mm aluminum silicate fiber (thermal conductivity ≤ 0.035W / (m・K)) and the surface temperature is ≤ 50℃.

[0016] Preferably, it is equipped with a gradient-activated composite zeolite rotor with a desorption zone temperature of 90-110℃. It is linked with the primary utilization module and adjusts the desorption air volume through an AI platform to achieve a 30% reduction in desorption air volume and a 45% reduction in energy consumption.

[0017] Preferably, the ratio of the heat pump drive source to the waste heat distribution of the workshop heating is 5:2, and the fully automatic control is achieved through a PLC+SCADA system, with a waste heat distribution response time of ≤5s and a control accuracy of ±3%.

[0018] Compared with existing technologies, the waste heat four-stage cascade utilization network system of the present invention has the following beneficial effects: 1. Four-stage cascade utilization, increasing waste heat utilization rate to 72%: By constructing a four-stage gradient path of "high-temperature preheating → medium-temperature drive → low-temperature heating," waste heat from RTO flue gas and desorption exhaust gas at different temperatures is gradually converted into energy for production and heating needs. The combination of plate-fin heat exchangers and heat pipes enables highly efficient heat exchange, increasing the waste heat utilization rate from 35% to 72% compared to traditional systems, significantly reducing enterprise energy consumption and operating costs.

[0019] 2. Multi-device collaborative integration significantly optimizes system energy efficiency: The gradient-activated composite zeolite rotor is deeply integrated with the waste heat utilization module. The AI ​​platform dynamically adjusts the desorption air volume, reducing air volume requirements by 30% and energy consumption by 45%. The 5:2 precise allocation mechanism between the heat pump drive source and workshop heating, combined with PLC+SCADA fully automatic control, maximizes the utilization of waste heat resources and improves the overall system operating efficiency by more than 50%.

[0020] 3. Intelligent dynamic control to adapt to complex operating conditions: Based on a VOCs concentration prediction model, the AI ​​platform optimizes data from 16 temperature / pressure measurement points in real time, responding and adjusting parameters such as bypass valve opening and heat pump power within one second. By simulating heat exchange strategies under different operating conditions through a digital twin, the system can adapt to fluctuations in exhaust gas concentration of ±20%, ensuring that heat exchange efficiency remains stable at over 90%, while reducing operation and maintenance costs and the need for manual intervention. Attached Figure Description

[0021] Figure 1 This is an overall flowchart of a four-stage waste heat utilization network system according to the present invention; Figure 2This is a flowchart illustrating the system operation control and energy efficiency feedback of a four-stage waste heat utilization network system according to the present invention. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0023] like Figure 1 and Figure 2 As shown, a four-stage waste heat utilization network system includes: The four-stage waste heat utilization pathways are as follows: Primary utilization: RTO exhaust gas (300℃) is preheated to 200℃ by a plate-fin heat exchanger to desorbed air from the rotor. The primary utilization module uses a plate-fin heat exchanger with a heat exchange area ≥80㎡, a heat exchange efficiency ≥85%, and an outlet temperature controlled at 200±5℃. It is equipped with a PID-regulated flue gas bypass valve with an opening accuracy of ±2%. Secondary utilization: The desorbed waste gas (110℃) is preheated to 150℃ by a heat pipe heat exchanger. The secondary utilization module adopts a copper-water heat pipe heat exchanger with a heat pipe diameter of 25mm, a length of 3m, a liquid filling rate of 60%, and a heat exchange efficiency of ≥82%. The inlet gas is preheated to 150±3℃, and the length ratio of the heat pipe evaporation section to the condensation section is 1:1.5. Level 3 utilization: 80℃ waste heat drives an absorption heat pump system. The level 3 utilization module includes an absorption heat pump unit (COP≥1.8), which uses 80℃ waste heat as the driving source to produce 40℃ cold water. The evaporator heat exchange efficiency is ≥75%, and the condenser outlet water temperature is controlled at 65±3℃. Level 4 utilization: The 50℃ low-temperature waste heat is used for workshop heating through finned tube radiators. The level 4 utilization module adopts finned tube radiators with a heat dissipation area of ​​≥500㎡. The 50℃ waste heat is dynamically distributed through an electric regulating valve (accuracy ±2%) to maintain the workshop temperature at 18-22℃. The radiator fin spacing is 3-5mm.

[0024] The waste heat utilization rate of the plate heat exchanger and heat pipe combined heat exchange device is increased from 35% to 72%. In the plate heat exchanger and heat pipe combined heat exchange device: The plate heat exchanger uses 316L stainless steel plates with a corrugation angle of 60° and a heat transfer coefficient ≥3000W / (㎡・K); the heat pipes are arranged in series with the plate heat exchanger, the overall heat loss is <5%, and the combined heat exchange efficiency is ≥90%. The AI ​​dynamic control platform optimizes heat exchange parameters based on a VOCs concentration prediction model. The platform monitors 16 temperature / pressure measurement points in real time (accuracy ±0.5℃ / ±1kPa) with a response time of <1s. It optimizes the bypass valve opening and heat pump power based on a digital twin with a control cycle of ≤10s.

[0025] The heat exchange efficiencies of the four-stage utilization paths are as follows: Level 1 ≥ 85%, Level 2 ≥ 82%, Level 3 ≥ 70%, and Level 4 ≥ 65%. The pipes are insulated with 100mm aluminum silicate fiber (thermal conductivity ≤ 0.035W / (m・K)) and the surface temperature is ≤ 50℃.

[0026] Equipped with a gradient-activated composite zeolite rotor, the desorption zone temperature is 90-110℃. It is linked with the primary utilization module and adjusts the desorption air volume through an AI platform, achieving a 30% reduction in desorption air volume and a 45% reduction in energy consumption.

[0027] The ratio of waste heat distribution between the heat pump drive source and the workshop heating is 5:2. Fully automatic control is achieved through a PLC+SCADA system, with a waste heat distribution response time of ≤5s and a control accuracy of ±3%.

[0028] Example: Upgrading of a four-stage waste heat utilization system in a printing company Application scenario: A packaging and printing company with an annual output value of over 500 million yuan has an existing RTO waste gas treatment system with a waste heat utilization rate of only 32%. The workshop relies on natural gas boilers for winter heating, with annual energy costs exceeding 8 million yuan.

[0029] System setup: Primary utilization: Install a plate-fin heat exchanger with a heat exchange area of ​​85㎡ and configure a PID-regulated flue gas bypass valve to transfer the heat of the 300℃ RTO exhaust gas to the rotor desorption air, and stably control the outlet temperature at 200±3℃. Secondary utilization: Deploy a copper-water heat pipe heat exchanger (25mm in diameter, 3m in length, and 60% liquid filling rate) to recover the waste heat from the 110℃ desorption exhaust gas and use it to preheat the intake gas to 152±2℃; Level 3 utilization: Introduce an absorption heat pump unit (COP=1.85) to drive the production of 40°C chilled water using 80°C waste heat for process cooling; Level 4 utilization: Install finned tube radiators with a heat dissipation area of ​​520㎡, and dynamically distribute 50℃ of waste heat through an electric regulating valve to maintain the workshop temperature at 19-21℃; Intelligent control: Deploy an AI dynamic control platform to monitor 16 temperature / pressure measurement points in real time, optimize heat exchange parameters based on VOCs concentration prediction model, and control cycle is 8 seconds.

[0030] Operating period: October 2023 - April 2024 (winter heating season), a total of 180 days of operation, 16 hours of operation per day.

[0031] Experimental data and performance verification: 1. Improved waste heat utilization rate: Before the upgrade, the system's waste heat utilization rate was 32%. The waste heat utilization rate of the system in this invention is 72.3%, an improvement of 40.3 percentage points; Data source: Statistics from the enterprise's energy management system, which monitors heat recovery and consumption at all levels in real time through heat flow meters and flow meters.

[0032] Energy consumption and cost reduction:

[0033] Calculation basis: Enterprise financial statements and equipment operation logs; desorption energy consumption is based on electricity meter readings.

[0034] 3. Effectiveness of intelligent regulation: Under conditions where VOC concentration fluctuates by ±25%, the system heat exchange efficiency remains stable at 91.2% ± 1.5%. The average response time of the bypass valve opening and heat pump power regulation is 0.8 seconds, with an regulation accuracy of ±1.8%. Verification method: By changing the VOCs concentration of the exhaust gas simulation device, the heat exchange efficiency and response time after the system parameters were adjusted were recorded.

[0035] 4. Actual measurement of equipment performance parameters: Single-stage plate-fin heat exchanger: heat exchange efficiency 86.3%, outlet temperature 200.5±2.8℃; Two-stage heat pipe heat exchanger: heat exchange efficiency 83.1%, inlet air preheated to 151.7±2.5℃; Heat pump evaporator heat exchange efficiency: 76.2%, condenser outlet water temperature: 64.8±2.3℃; Measuring tools: Type K thermocouple (accuracy ±0.5℃), ultrasonic flow meter (accuracy ±1%).

[0036] 5. Economic benefit calculation: Annual energy cost savings: 4.8 million yuan; Investment payback period: 1.8 years (system upgrade cost: 8.6 million yuan). Calculation basis: Based on a natural gas price of 3.5 yuan / m³ and an electricity price of 0.8 yuan / kW·h.

[0037] Comparative experiments and verification of technological advantages: 1. Comparison with traditional single-stage waste heat recovery systems: Traditional systems have a waste heat utilization rate of only 35%, while the system of this invention improves it by 106%. Natural gas consumption during the heating season decreased by 520,000 cubic meters (compared to 1 million cubic meters for traditional systems).

[0038] 2. Comparison with similar multi-stage recycling systems: A competitor's multi-stage system has a waste heat utilization rate of 58%, while the system of this invention improves it by 24.7%. The desorption energy consumption of the system of this invention is 22% lower than that of competing products, which is attributed to AI dynamic control and equipment collaborative optimization.

[0039] 3. Stability verification: After 180 days of continuous operation without any downtime, the equipment's heat exchange efficiency decay rate is less than 3%, which is significantly better than the industry average (5%-8%).

[0040] In summary, the present invention provides a four-stage waste heat utilization network system that achieves efficient recovery and precise distribution of waste heat through a four-stage utilization path, a plate-heat pipe combined heat exchange device, and an AI dynamic control platform. The reliability and economy of the technical solution have been verified in practical applications, providing a replicable innovative model for industrial waste heat utilization.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A four-stage cascade utilization network system for waste heat, characterized in that, include: The four-stage waste heat utilization pathways are as follows: Primary utilization: RTO exhaust gas is preheated to 200°C by a plate-fin heat exchanger for desorbed air from the rotor; Secondary utilization: The desorbed waste gas is preheated to 150°C by a heat pipe heat exchanger; Level 3 utilization: 80℃ waste heat drives an absorption heat pump system; Level 4 utilization: Low-temperature waste heat at 50℃ is used for workshop heating through finned tube radiators; Plate heat exchanger combined with heat pipe heat exchange device; The AI ​​dynamic control platform optimizes heat exchange parameters based on a VOCs concentration prediction model.

2. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The primary utilization module adopts a plate-fin heat exchanger with a heat exchange area ≥80㎡, a heat exchange efficiency ≥85%, and an outlet temperature controlled at 200±5℃. It is equipped with a PID-regulated flue gas bypass valve with a bypass valve opening adjustment accuracy of ±2%.

3. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The secondary utilization module uses a copper-water heat pipe heat exchanger with a heat pipe diameter of 25mm, a length of 3m, a liquid filling rate of 60%, a heat exchange efficiency of ≥82%, and an inlet air preheating to 150±3℃. The length ratio of the heat pipe evaporation section to the condensation section is 1:1.

5.

4. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The three-level utilization module includes an absorption heat pump unit with a COP ≥ 1.8, which uses 80℃ waste heat as a driving source to produce 40℃ cold water, has an evaporator heat exchange efficiency ≥ 75%, and controls the condenser outlet water temperature at 65±3℃.

5. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The fourth-level utilization module uses finned tube radiators with a heat dissipation area of ​​≥500㎡. It dynamically distributes 50℃ of waste heat through an electric regulating valve to maintain the workshop temperature at 18-22℃. The radiator fin spacing is 3-5mm.

6. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: In the plate heat exchanger and heat pipe combined heat exchange device: The plate heat exchanger uses 316L stainless steel plates with a corrugation angle of 60° and a heat transfer coefficient of ≥3000W / (㎡・K). The heat pipes and plate heat exchangers are arranged in series, with an overall heat loss of less than 5% and a combined heat exchange efficiency of ≥90%.

7. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The AI ​​dynamic control platform monitors 16 temperature / pressure measurement points in real time with a response time of <1s. Based on the digital twin, it optimizes the bypass valve opening and heat pump power with a control cycle of ≤10s.

8. The waste heat four-stage cascade utilization network system according to claim 1, characterized in that: The heat exchange efficiencies of the four-stage utilization paths are as follows: Level 1 ≥ 85%, Level 2 ≥ 82%, Level 3 ≥ 70%, and Level 4 ≥ 65%. The pipes are insulated with 100mm aluminum silicate fiber, with a thermal conductivity ≤ 0.035W / (m・K) and a surface temperature ≤ 50℃.

9. A waste heat four-stage cascade utilization network system according to claim 1, characterized in that: It is equipped with a gradient-activated composite zeolite rotor, with a desorption zone temperature of 90-110℃, and is linked with the primary utilization module to adjust the desorption air volume through an AI platform.

10. A waste heat four-stage cascade utilization network system according to any one of claims 1-9, characterized in that: The ratio of waste heat distribution between the heat pump drive source and the workshop heating is 5:

2. Fully automatic control is achieved through a PLC+SCADA system, with a waste heat distribution response time of ≤5s and a control accuracy of ±3%.

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