Waste gas waste heat recovery system
By using heat pump-driven deep dehumidification and synergistic recovery of sensible and latent heat, the problem of recovering low-grade exhaust gas has been solved, improving the energy utilization rate and environmental protection effect of cigarette factories.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA TOBACCO ZHEJIANG IND CO LTD
- Filing Date
- 2025-05-26
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies are insufficient for efficiently recovering the heat energy from low-grade exhaust gases from cigarette factories, leading to energy waste and environmental thermal pollution. Furthermore, traditional heat exchangers are prone to corrosion and scaling, resulting in a short service life.
The technology employs deep dehumidification driven by a heat pump and synergistic recovery of sensible and latent heat. By coupling a flue gas heat exchanger and an air source heat pump, it achieves efficient recovery and utilization of low-grade exhaust gas.
It improved the energy efficiency of cigarette factories, reduced carbon emissions, lowered maintenance costs, and achieved efficient conversion and utilization of low-grade waste heat.
Smart Images
Figure CN224188631U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of industrial waste heat recovery technology, and specifically to a waste gas waste heat recovery system. Background Technology
[0002] Cigarette production generates various industrial waste gases, mainly categorized into two types: high-temperature waste gases and low-grade waste gases. High-temperature waste gases are represented by boiler flue gas, which has a relatively high temperature and for which waste heat recovery technology is relatively mature. Low-grade waste gases are mainly waste gases from the tobacco processing dehumidification process, with temperatures typically ranging from 20-35℃, and rarely exceeding 40℃. These gases are characterized by low heat grade and low calorific value, making their recovery and utilization more difficult.
[0003] For the recovery of waste heat from high-temperature flue gas (such as boiler flue gas), existing technologies have achieved efficient recovery through the use of heat exchangers and waste heat boilers, and have successfully applied them to production or energy conversion processes. However, the recovery of low-grade waste heat still faces many challenges. Because the temperature of exhaust gas is close to that of the environment, the small temperature difference makes it difficult for traditional heat exchange technologies to effectively extract the heat energy. Although the total heat of low-grade waste heat is considerable, direct emission not only leads to energy waste but may also exacerbate environmental thermal pollution.
[0004] Furthermore, the exhaust gas contains tar and acidic substances (pH 3-5), making the heat exchanger prone to scaling and corrosion. Data shows that the service life of ordinary carbon steel heat exchangers under these conditions is less than one year, with related maintenance costs increasing by up to 30%. Although heat pump technology has certain application prospects in waste heat recovery, existing technologies are not yet fully adapted to the complex operating conditions of cigarette factories. While the total amount of low-grade waste heat is large, its dispersed distribution means that direct emissions do not meet energy conservation and environmental protection requirements.
[0005] To address the aforementioned technological gaps, this invention proposes a heat pump coupled recovery system, aiming to overcome the technical challenge of co-recovering waste heat from low-grade exhaust gas and flue gas. This system not only fills the gaps in existing technologies for low-temperature waste heat recovery but also effectively improves the overall energy utilization rate of cigarette factories and reduces carbon emissions, thus possessing significant environmental and economic value. Utility Model Content
[0006] In view of the above-mentioned deficiencies or defects in the existing technology, this utility model provides a waste heat recovery system for exhaust gas. Targeting the characteristics of high humidity and a large proportion of latent heat in the exhaust gas from cigarette factories, it breaks through the technical bottleneck of low efficiency in traditional condensation waste heat recovery by using heat pump-driven deep dehumidification and synergistic recovery of sensible / latent heat. This enables the recovery of exhaust gas and the efficient utilization of low-grade exhaust heat.
[0007] To achieve the above objectives, this utility model provides a waste heat recovery system for exhaust gas, comprising:
[0008] The boiler flue gas waste heat recovery subsystem includes a flue gas heat exchanger for recovering waste heat from boiler flue gas; the recovered boiler flue gas is introduced into the flue gas heat exchanger through the heat medium inlet; the return water from the heating system is introduced into the flue gas heat exchanger through the cold medium inlet; and the heat medium outlet of the flue gas heat exchanger is connected to a hot water storage tank.
[0009] The dehumidified gas recovery subsystem includes an air source heat pump; the dehumidified gas is connected to the heat extraction end of the air source heat pump; the return water of the heating system is connected to the heat supply end of the air source heat pump; and the outlet of the heat supply end of the air source heat pump is connected to a hot water storage tank.
[0010] Through the above technical solution, the technology of deep dehumidification driven by heat pump and synergistic recovery of sensible / latent heat has been used to break through the technical bottleneck of low efficiency of waste heat recovery in traditional condensation method, reduce the temperature of exhaust gas below the dew point, and realize the efficient utilization of low-grade exhaust waste heat.
[0011] Furthermore, the boiler flue gas waste heat recovery subsystem includes at least two flue gas heat exchangers; the at least two flue gas heat exchangers are arranged along the direction of flue gas discharge flow.
[0012] Furthermore, in the flue gas waste heat recovery subsystem, the flue gas flow direction is opposite to the return water flow direction of the heating system.
[0013] Furthermore, the heat medium outlet of the flue gas heat exchanger is connected to the first user terminal and the first water inlet of the hot water storage tank via pipelines.
[0014] Furthermore, a first solenoid valve and a second solenoid valve are respectively installed on the pipeline connecting the heat medium outlet of the flue gas heat exchanger to the first user end and on the pipeline connecting the heat medium outlet of the flue gas heat exchanger to the hot water storage tank.
[0015] Furthermore, the heat medium outlet of the flue gas heat exchanger is connected to the hot water storage tank via a main pipeline; a branch pipeline is provided on the main pipeline and connected to it; the branch pipeline is connected to the first user terminal; a first three-way valve is provided at the junction of the branch pipeline and the main pipeline to control the flow direction of the return water of the heating system.
[0016] Furthermore, a first temperature sensor is provided at the outlet of the heat medium.
[0017] Furthermore, the hot water storage tank is equipped with a second temperature sensor for detecting the water temperature inside the hot water storage tank.
[0018] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of one embodiment of the waste heat recovery system of this utility model.
[0020] Explanation of reference numerals in the attached figures
[0021] 1. Heating system return water; 2. Boiler flue gas recovery; 3. Flue gas heat exchanger; 4. Air source heat pump; 5. Heating end; 6. Heat extraction end; 7. Exhaust gas dehumidification; 8. Hot water storage tank. Detailed Implementation
[0022] The specific embodiments of this utility model are described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.
[0023] In this utility model, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the orientation in the assembled and used state. "Inner" and "outer" refer to the inner and outer sides relative to the outline of each component itself.
[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0025] This utility model provides a waste heat recovery system for exhaust gas, such as Figure 1 As shown, the waste heat recovery system includes a boiler flue gas waste heat recovery subsystem and a dehumidified gas recovery subsystem.
[0026] The boiler flue gas waste heat recovery subsystem includes a flue gas heat exchanger 3 for recovering the waste heat of boiler flue gas 2. The recovered boiler flue gas 2 is introduced into the flue gas heat exchanger 3 through the heat medium inlet, and the heating system return water 1 is introduced into the flue gas heat exchanger 3 through the cold medium inlet. The heat medium outlet of the flue gas heat exchanger 3 is connected to a hot water storage tank 8.
[0027] After passing through the flue gas heat exchanger 3, the recovered boiler flue gas 2 transfers heat to the return water 1 of the heating system, thereby increasing the temperature of the return water 1.
[0028] In one optional embodiment, the boiler flue gas waste heat recovery subsystem includes at least two flue gas heat exchangers 3. The at least two flue gas heat exchangers 3 are arranged along the direction of flue gas discharge flow. Further, the flue gas flow direction is opposite to the flow direction of the return water 1 of the heating system.
[0029] The following provides two piping connection methods for the heat medium outlet of flue gas heat exchanger 3:
[0030] Specific Implementation Method 1: The heat medium outlet of the flue gas heat exchanger 3 is connected to the first user terminal and the first water inlet of the hot water storage tank 8 via pipelines. Further, a first solenoid valve and a second solenoid valve are respectively installed on the pipeline connecting the heat medium outlet of the flue gas heat exchanger 3 to the first user terminal and on the pipeline connecting the heat medium outlet of the flue gas heat exchanger 3 to the hot water storage tank 8.
[0031] Specific Implementation Method Two: The heat medium outlet of the flue gas heat exchanger 3 is connected to the hot water storage tank 8 via a main pipeline. A branch pipeline is provided on the main pipeline, and the branch pipeline is connected to the first user terminal. A first three-way valve is installed at the junction of the branch pipeline and the main pipeline to control the flow direction of the return water 1 of the heating system. Further, the first three-way valve here is a solenoid valve.
[0032] Through the above-described specific implementation methods one and two, the flow direction of the return water 1 of the heating system can be controlled by opening and closing the "first solenoid valve and second solenoid valve" or the "first three-way valve" according to actual needs.
[0033] Furthermore, a first temperature sensor is installed at the outlet of the heat medium. The first temperature sensor, the first three-way valve, the first solenoid valve, and the second solenoid valve are all electrically connected to the controller. The controller controls the opening and closing of the "first solenoid valve and second solenoid valve" or the "first three-way valve" based on the temperature feedback from the first temperature sensor.
[0034] Thus, the flow direction of the return water 1 of the heating system can be determined based on the water temperature at the outlet of the heat medium of the flue gas heat exchanger 3 measured by the first temperature sensor. Taking specific implementation method one as an example, specifically, if the outlet temperature of the heat medium of the flue gas heat exchanger 3 can meet the heat requirements of the first user, the second solenoid valve is closed and the first solenoid valve is opened to directly supply heat to the first user. If the outlet temperature of the heat medium of the flue gas heat exchanger 3 cannot meet the heat requirements of the first user, the second solenoid valve is opened and the first solenoid valve is closed, and the return water 1 of the heating system enters the hot water storage tank 8.
[0035] Of course, more pipelines can be added and solenoid valves can be installed on these pipelines. If the water temperature at the outlet of the heat medium from the flue gas heat exchanger 3 is lower than the heat requirement of the first user but meets the heat requirement of the second user, the return water 1 of this part of the heating system can be directly supplied to the second user.
[0036] The exhaust gas recovery subsystem is connected to the exhaust outlet of the tobacco production process via pipelines to recover exhaust gases carrying tobacco odors. The exhaust gas in this invention refers to the exhaust gas removal process in the tobacco processing of a cigarette factory. Due to the presence of a certain temperature, some gases are emitted from the tobacco leaves or shreds into the working environment. Currently, exhaust fans are typically used to directly discharge these gases outdoors. This technical solution recovers and reuses all of these gases.
[0037] Specifically, the exhaust gas recovery subsystem includes an air source heat pump 4. Exhaust gas 7 is connected to the heat extraction end 6 of the air source heat pump 4. The return water 1 of the heating system is connected to the heating end 5 of the air source heat pump 4. The outlet of the heating end 5 of the air source heat pump 4 is connected to a hot water storage tank 8. In this way, the exhaust gas can be recovered, achieving efficient utilization of low-grade exhaust heat.
[0038] Furthermore, the hot water storage tank 8 is equipped with a second temperature sensor for detecting the water temperature inside the hot water storage tank 8. This second temperature sensor is also electrically connected to the controller.
[0039] In this way, the operating mode of the air source heat pump 4 can be dynamically adjusted according to the target water temperature of the hot water storage tank 8 (e.g., 50-55℃). Specifically, if the second temperature sensor detects that the water temperature of the hot water storage tank 8 is ≥50℃, it is directly supplied to the user end 9; if it is <50℃, the air source heat pump 4 is activated to improve the quality of the exhaust heat, thereby reducing air pollution while increasing revenue, and reducing energy waste while improving energy utilization.
[0040] This system is conducive to the efficient conversion of low-grade waste heat. Through heat pump coupling recovery technology, it can recover the latent heat of exhaust gas with humidity >80% and temperature 20-40℃, and at the same time, it can efficiently utilize the sensible heat of flue gas with temperature 80-120℃.
[0041] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0042] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.
[0043] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.
Claims
1. A waste heat recovery system for exhaust gas, characterized in that, include: The boiler flue gas waste heat recovery subsystem includes a flue gas heat exchanger (3) for recovering the waste heat of the boiler flue gas (2); the recovered boiler flue gas (2) is connected to the flue gas heat exchanger (3) through the heat medium inlet; the return water (1) of the heating system is connected to the flue gas heat exchanger (3) through the cold medium inlet; the heat medium outlet of the flue gas heat exchanger (3) is connected to the hot water storage tank (8); The dehumidification gas recovery subsystem includes an air source heat pump (4); dehumidification gas (7) is connected to the heat extraction end (6) of the air source heat pump (4); the return water (1) of the heating system is connected to the heat supply end (5) of the air source heat pump (4); the outlet of the heat supply end (5) of the air source heat pump (4) is connected to the hot water storage tank (8).
2. The waste heat recovery system according to claim 1, characterized in that, The boiler flue gas waste heat recovery subsystem includes at least two flue gas heat exchangers (3); the at least two flue gas heat exchangers (3) are arranged along the direction of flue gas discharge flow.
3. The waste heat recovery system according to claim 2, characterized in that, In the flue gas waste heat recovery subsystem, the flue gas flow direction is opposite to the flow direction of the return water (1) of the heating system.
4. The waste heat recovery system according to claim 1, characterized in that, The heat medium outlet of the flue gas heat exchanger (3) is connected to the first user terminal and the first water inlet of the hot water storage tank (8) through pipelines.
5. The waste heat recovery system according to claim 4, characterized in that, A first solenoid valve and a second solenoid valve are respectively installed on the pipeline connecting the heat medium outlet of the flue gas heat exchanger (3) to the first user end and on the pipeline connecting the heat medium outlet of the flue gas heat exchanger (3) to the hot water storage tank (8).
6. The waste heat recovery system according to claim 4, characterized in that, The heat medium outlet of the flue gas heat exchanger (3) is connected to the hot water storage tank (8) through the main pipeline; a branch pipeline is provided on the main pipeline and connected to it; the branch pipeline is connected to the first user end; a first three-way valve is provided at the junction of the branch pipeline and the main pipeline to control the flow direction of the return water (1) of the heating system.
7. The waste heat recovery system according to claim 4, characterized in that, A first temperature sensor is installed at the outlet of the heat medium.
8. The waste heat recovery system according to claim 1, characterized in that, The hot water storage tank (8) is equipped with a second temperature sensor for detecting the water temperature inside the hot water storage tank (8).