Cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization

Abstract

The invention discloses a cooling and separating integrated multi-unit treatment method for flue gas waste heat utilization, which is characterized in that a plurality of groups of parallel W-shaped unit treatment channels are formed in a flue through specially designed, mutually parallel and periodically arranged dividing wall plates, and flue gas flows in the W-shaped unit treatment channels in a bending manner; in cooperation with a water flowing change and multi-unit parallel heat interaction mode, flue gas is fully cooled, and meanwhile reverse flowing water is heated; flue gas in the W-shaped unit treatment channels collides with an incident flow wall surface, after sufficient cooling, once the flue gas temperature is lower than an acid condensation temperature and a dew point temperature, acid steam and water vapor in the flue gas are condensed on the surfaces of the multiple groups of parallel W-shaped unit treatment channels, and condensed liquid and dust particles and tar particles in the flue gas are captured by wall surfaces of dividing wall plates; and after cooling phase change, secondary capture is performed on the efficient wall surface in the W-shaped unit treatment channel, so that gas mixture liquefaction and separation are achieved, and the comprehensive effects of waste heat utilization and efficient separation of dust, tar and condensed acid are achieved.

Description

Technical Field

[0001] The present invention relates to the field of deep utilization of waste heat from low-temperature flue gas of coal boilers, and in particular to a high-efficiency cooling and separation integrated multi-unit processing method for waste heat utilization of flue gas. Background Art

[0002] Flue gas waste heat is divided into high-temperature waste heat (flue gas temperature>600℃), medium-temperature waste heat (flue gas temperature in the range of 300~600℃) and low-temperature waste heat (flue gas temperature<300℃) according to its quality. Among them, the utilization of high-temperature and medium-temperature flue gas waste heat is relatively more fully developed. However, the utilization of low-temperature flue gas is still greatly restricted by various factors. Although the exhaust temperature of low-temperature flue gas has been continuously optimized with the development of waste heat utilization technology, material technology and control technology in recent years; however, the exhaust temperature of flue gas from most coal-fired boilers, including other process waste heat boilers of the same type, is still as high as 120-140℃. A large amount of practical data proves that when the exhaust temperature is high, the flue gas takes away more heat, and the boiler efficiency will drop by as much as 3-8%. Practice shows that for every 10-15℃ drop in boiler exhaust temperature, the boiler efficiency will increase by 1%. Essentially, the factors that affect flue gas utilization are divided into two aspects: First, the technical aspect, which is manifested in the complexity of the flue gas itself, namely, the stability of flue gas flow, temperature and pressure (fluctuation of flue gas), low-temperature corrosion caused by flue gas components, and the difficulty in maintaining heat exchange efficiency due to the complexity of flue gas components; on the other hand, it is the influence of corresponding economic indicators. Under the current environmental conditions of sustainable development, the constraints of economic efficiency indicators are essentially in a relatively secondary position.

[0003] The core factors that affect flue gas cooling and waste heat recovery, especially low-temperature flue gas cooling and waste heat recovery, are technical problems caused by the complex characteristics of the flue gas itself. There are methods similar to flue gas heat accumulators to deal with the fluctuations in flue gas flow, temperature and pressure. With certain control methods, they can be improved accordingly, such as a ceramic heat accumulator for waste heat flue gas recovery in CN202323119767.X. However, for the use of fluid flow control technology, material technology, and enhanced heat exchange technology, there is a lack of a comprehensive and efficient solution system for mutually coupled complex systemic problems, such as low-temperature corrosion problems, environmental protection problems, and deep utilization of waste heat caused by complex components.

[0004] The mechanism characteristics of these core issues that hinder the sufficient cooling of coal-fired flue gas and the deep utilization of flue gas waste heat are discussed and analyzed respectively.

[0005] 1) Low temperature corrosion problem, flue gas is difficult to fully cool, and waste heat cannot be efficiently utilized The key to low-temperature corrosion is that the flue gas contains acid vapor and water vapor (under given pressure conditions, when the flue gas temperature is higher than a certain corresponding value, it exists in gaseous form). When the flue gas temperature in a certain area is lower than the corresponding acid vapor dew point temperature, acid condensation occurs in the corresponding area. This condensation is mainly concentrated on the wall of the flue gas duct and the surface of the flue gas heat exchanger with lower temperature, and the direct result is corrosion. Severe flue gas leakage will occur. Of course, traditional metal type heat exchangers cannot carry out deep utilization of flue gas waste heat. In the boiler exhaust waste heat recovery system, coal is burned as the main fuel to produce SO 2 、SO 3 Highly corrosive gases such as SO 3 When the flue gas temperature drops to a certain level (≤200°C), it will generate sulfuric acid vapor when it meets water vapor. 3 When the content reaches 0.005%, the dew point temperature of the flue gas will rise to above 150℃, causing serious low-temperature corrosion of the equipment, affecting the safe operation of the unit and causing serious economic losses. After proper desulfurization treatment, considering the effect of the temperature boundary layer, the exhaust temperature of the flue gas will be more likely to be maintained in the range of 120-140℃. Thus, the corresponding metal wall temperature is ensured to be higher than the condensing acid dew point temperature, trying to fundamentally avoid the condensing acid corrosion problem of the flue gas. This is also the key to the inability to fully cool the coal-fired flue gas and thus the inability to deeply carry out the waste heat utilization. At present, the waste heat recovery method commonly used in coal-fired boilers is to use steel pipe economizers to complete waste heat recovery while cooling the flue gas. The pipe material is generally No. 20 carbon steel, which has the advantages of compact structure, high strength, high pressure resistance and reliable operation, but faces the problems of wear, dust accumulation, blockage and low-temperature corrosion, and the safety and stability of the unit will be greatly reduced. This is also the fundamental reason why complex phase and flow flue gas are difficult to be fully cooled, and it is also the bottleneck of the utilization of waste heat of medium and low temperature flue gas.

[0006] 2) Low heat exchange efficiency Boiler flue gas, due to fuel characteristics and combustion, is usually a gas-solid-liquid three-phase coupled fluid. As mentioned above, the flow characteristics of this three-phase coupling are also affected by the flue gas temperature, and become more complicated when considering the presence of condensed acid and condensed water. The liquid phase in the flue gas is usually tar-like substances with high viscosity, which are distributed in the flue gas in different particle sizes; the solid phase is mainly particles of different particle sizes (according to the different forms of particulate matter in the flue gas, the primary particulate matter emitted by coal-fired boilers can be divided into filterable particulate matter (FPM) and condensable particulate matter (CPM), which together constitute the total particulate matter (TPM) emitted by coal-fired combustion); the gas components are directly related to the fuel and combustion characteristics, and the changes are complex. These are the root causes of environmental pollution, thermal pollution and obstacles to heat exchange efficiency. Tar and dust in the components of flue gas will directly affect the operating characteristics and life of subsequent filters; condensed acid will also cause corrosion problems in filters. For traditional metal heat exchange methods, the complex components of flue gas restrict the flue gas temperature value on the one hand, and on the other hand, due to the accumulation and adhesion of smoke particles and tar-like substances, the heat exchange efficiency of the flue gas heat exchanger will inevitably be greatly reduced.

[0007] Of course, for the current environmental protection requirements, another major problem restricting the application of coal-fired boilers is the corresponding pollution problem. This problem is manifested in several aspects: first, direct environmental pollution (dust, oil, acid) caused by the components of the flue gas itself; second, thermal pollution to the environment; third, indirect pollution caused by flue gas post-treatment, such as secondary pollution from bag filters. While reducing pollution, improving the efficiency and stability of the dust collector and extending its service life are also another problem that needs to be solved in conjunction with the deep utilization of flue gas.

[0008] In order to address the above two key issues that make it difficult to carry out flue gas cooling and deep recovery of flue gas waste heat, and even make it impossible for coal-fired boilers to continue to be used, it is urgent to build a mechanism that is corrosion-resistant, strengthens dust, oil and acid separation, and has relatively stable heat exchange efficiency, so as to promote the efficient implementation of deep utilization of flue gas waste heat. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a cooling and separation integrated multi-unit treatment method based on the utilization of waste heat of fully cooled flue gas, so as to achieve the comprehensive effects of waste heat utilization, efficient separation of dust and tar, and condensed acid separation.

[0010] In order to achieve the first invention objective, the present invention provides the following technical solutions: A cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization, through specially designed, parallel and periodically arranged partition plates, to form multiple sets of parallel W-shaped unit treatment channels in the flue, the multiple sets of parallel W-shaped unit treatment channels include secondary flow surfaces and oncoming wall surfaces arranged alternately, and an angle is formed between the secondary flow surfaces and the oncoming wall surfaces, and the complex multiphase flow flue gas is fully cooled while bending and flowing in the multiple sets of parallel W-shaped unit treatment channels, forming a high-efficiency composite separation and purification mechanism; A water flow cavity is provided in the partition wall, and water flows into the water flow cavity in the opposite direction to the flue gas flow. With the change of water flow and the parallel heat interaction of multiple units, the flue gas is fully cooled. The cooling process is not limited by the traditional flue gas condensation dew point. The treated flue gas temperature breaks through the original exhaust temperature of more than 120°C and reaches a temperature level that is only 5-10°C higher than the inlet water temperature. At the same time, the water in the reverse flow is heated, which lays the foundation for overcoming the limitation of flue gas emission temperature. The complex multiphase flowing flue gas collides with the oncoming wall. During the continuous cooling process, once the flue gas temperature is lower than the acid condensing temperature and the dew point temperature, the acid vapor and water vapor in the flue gas will condense on the surface of multiple sets of parallel W-type unit treatment channels. The condensed liquid and the dust particles and tar particles in the flue gas are captured by the wall of the partition plate, and flow to the bottom of the flue along the wall under the action of gravity, and converge into the separation chamber from the flue bottom plate. Considering the flow direction of the flue gas through the exclusive process design, the periodic changes produced according to the requirements form a sufficient cooling and inertial separation mechanism for the flue gas with complex components and phases; after the cooling phase change, it is captured twice by the efficient wall in the W-type unit treatment channel, and the gas mixture is liquefied and separated, which plays a comprehensive role in waste heat utilization and efficient separation of dust, tar and condensed acid.

[0011] The effects of the flue gas bending flow in the W-shaped unit treatment channel include two aspects: 1) Through the change of flow direction, the larger particles in the flue gas are separated based on inertial separation; 2) As the flue gas temperature in the flue decreases, the gradually condensed large particle droplets are separated through inertial separation.

[0012] Preferably, the partition plates are arranged in parallel and periodically, and the flue bottom plate is arranged to be inclined downward along the flue gas flow direction so that the separated dust particles and condensed liquid can flow to the bottom of the separation bin under the action of gravity.

[0013] Preferably, multiple groups of periodically arranged partition plates are provided, and the multiple groups of partition plates form multiple groups of parallel W-shaped unit treatment channels in the flue, and both sides of each wall section thereof exchange heat with the flue gas. Considering the characteristics of the wall material in the invention, the flue gas will be efficiently and fully cooled, and the goal of fully utilizing the waste heat of the flue gas can be achieved based on this; at the same time, considering the material of the multiple groups of parallel W-shaped unit treatment channels, the flue gas is cooled to an end difference of only 5-10°C higher than the inlet water temperature, which fundamentally breaks through the bottleneck that the waste heat of traditional flue gas is limited by the condensation temperature, and at the same time lays the foundation for a substantial increase in the subsequent flue gas treatment life.

[0014] Preferably, each group of parallel W-shaped unit processing channels forms multiple processing units through secondary flow surfaces and upstream walls, and the cooling and separation of the flue gas are efficiently promoted; each processing unit includes a group of secondary flow surfaces and upstream walls adjacent thereto, and multiple processing units realize periodic changes in the flow direction of the flue gas.

[0015] Preferably, the multiple sets of parallel W-shaped unit processing channels also include horizontally arranged inlet faces and outlet faces, and the inlet faces and outlet faces are distributed and connected with secondary flow faces. The flue gas flows from the inlet faces through the multiple sets of parallel W-shaped unit processing channels to the outlet faces.

[0016] Preferably, the partition plates are made of corrosion-resistant and heat-conductive materials, so that the heat recovery effect is determined by the choice of partition plate material. While fundamentally ensuring sufficient cooling of the flue gas, multiple sets of parallel W-shaped unit processing channels are combined to efficiently achieve cooling and separation of multi-phase flue gas.

[0017] Preferably, the partition plate is made of fluoroplastic, preferably polytetrafluoroethylene; the corresponding wall thickness is 3mm-6.4mm.

[0018] Preferably, the upper portion of the separation chamber is communicated with the flue, and the bottom thereof is conical, so that the separated dust particles and condensed liquid particles converge to the bottom of the separation chamber under the action of gravity.

[0019] Preferably, the bottom of the separation bin is equipped with an external compressed air and water purge system for sweeping out the air flow, so as to blow out the dust particles and condensed liquid particles that converge at the bottom of the separation bin.

[0020] Preferably, the flue bottom plate, partition plate and separation chamber are detachably connected to facilitate cleaning and a standard structure that can be detachably replaced, and the number and parameters of the units are adjusted according to the actual flue gas flow being processed.

[0021] The present invention has significant technical effects due to the adoption of the above technical solution: The present invention achieves the comprehensive effects of waste heat utilization and efficient separation of dust, tar and condensed acid through exclusive process design, sufficient cooling and inertial separation of flue gas with complex components and phases, and efficient wall capture after phase change to liquefy and separate the gas mixture. It specifically solves 1) the problem that waste heat cannot be fully utilized due to condensed acid corrosion in flue gas, 2) dust and tar substances in flue gas are effectively separated through specially designed airflow organization mode, thus reducing the burden of subsequent processing and extending the life of subsequent equipment; 3) the multi-unit processing mode with adjustable number greatly improves the processing and heat exchange efficiency. The method of the present invention achieves waste heat utilization and at the same time, the temperature of the treated flue gas breaks through the limitation of the original exhaust temperature of more than 120°C. The flue gas is fully cooled to a temperature level that is only 5-10℃ higher than the inlet water temperature; at the same time, the counter-flowing water is heated, which lays the foundation for overcoming the temperature limitation of flue gas emission, and realizes the efficient separation of solid particles such as dust and tar in the flue gas mixture, and the separation of condensed acids such as acid vapor and water vapor in the flue gas. It achieves the comprehensive effects of liquid condensation, liquid separation and solid separation in the heat exchange system, providing a new idea for the utilization of flue gas waste heat and efficient flue gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of an apparatus using the present cooling and separation integrated multi-unit processing method.

[0023] Figure 2 The figure is a schematic diagram of the flow of flue gas and water in a device using the present integrated cooling and separation multi-unit treatment method.

[0024] Figure 3 The figure is a schematic diagram of the flow direction of flue gas and water in the flue of the device using the cooling and separation integrated multi-unit treatment method.

[0025] Figure 4 This is a right side view of an apparatus using the present cooling and separation integrated multi-unit processing method.

[0026] Figure 5 It is a schematic diagram of the inclination slope θ in the device using the present cooling and separation integrated multi-unit processing method.

[0027] In the attached drawings: 1- partition plate, 2- W-type unit processing channel, 3- water flow chamber, 4- flue bottom plate, 5- separation chamber. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] A cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization, through specially designed, parallel and periodically arranged partition plates 1, a plurality of parallel W-shaped unit treatment channels 2 are formed in the flue, the plurality of parallel W-shaped unit treatment channels 2 include secondary flow surfaces and oncoming wall surfaces alternately arranged, and an angle is formed between the secondary flow surfaces and the oncoming wall surfaces, such as Figure 1 As shown, in the device using the cooling and separation integrated multi-unit treatment method, the flue is divided by parallel and periodically arranged partition plates 1, and multiple groups of parallel W-shaped unit treatment channels 2 are formed in the flue. While the complex multiphase flow flue gas bends and flows in the multiple groups of parallel W-shaped unit treatment channels 2, it is fully cooled to form a high-efficiency composite separation and purification mechanism; like Figure 2 As shown in the flue gas running direction, a water flow chamber 3 is provided in the partition plate 1, and water in the opposite direction of the flue gas running is introduced into the water flow chamber 3. With the change of water flow and the parallel heat interaction of multiple units, the flue gas is fully cooled. The cooling process is not limited by the traditional flue gas condensation dew point. The treated flue gas temperature breaks through the original exhaust temperature of more than 120°C. The flue gas is fully cooled to a temperature level that is only 5-10°C higher than the inlet water temperature. At the same time, the water in the reverse flow is heated, which lays the foundation for overcoming the limitation of flue gas emission temperature from this perspective. like Figure 3 The flow direction of flue gas and water in the flue shown in the figure, the complex multiphase flow flue gas collides with the oncoming wall, after being fully cooled, once the flue gas temperature is lower than the acid condensation temperature and the dew point temperature, the acid vapor and water vapor in the flue gas will condense on the surface of multiple sets of parallel W-type unit treatment channels 2, and the condensed liquid and the dust particles and tar particles in the flue gas are captured by the wall of the partition plate 1, and flow to the bottom of the flue along the wall under the action of gravity, and converge into the separation chamber 5 from the flue bottom plate 4. Considering the flow direction of the flue gas through the exclusive process design, the periodic changes generated according to the requirements form a sufficient cooling and inertial separation mechanism for the flue gas with complex components and phases; after the cooling phase change, it is captured twice by the efficient wall in the W-type unit treatment channel 2, and the gas mixture is liquefied and separated, which plays a comprehensive role in waste heat utilization and efficient separation of dust, tar and condensed acid.

[0031] The effects of the flue gas bending flow in the W-shaped unit processing channel 2 include two aspects: 1) through the change of flow direction, the larger particles in the flue gas are separated based on inertial separation; 2) as the flue gas temperature in the flue decreases, the gradually condensed large particle droplets are separated through inertial separation.

[0032] Example 2

[0033] A cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization, through specially designed, parallel and periodically arranged partition plates 1, a plurality of parallel W-shaped unit treatment channels 2 are formed in the flue, the plurality of parallel W-shaped unit treatment channels 2 include secondary flow surfaces and oncoming wall surfaces alternately arranged, and an angle is formed between the secondary flow surfaces and the oncoming wall surfaces, such as Figure 1 As shown, in the device using the cooling and separation integrated multi-unit treatment method, the flue is divided by parallel and periodically arranged partition plates 1, and multiple groups of parallel W-shaped unit treatment channels 2 are formed in the flue. While the complex multiphase flow flue gas bends and flows in the multiple groups of parallel W-shaped unit treatment channels 2, it is fully cooled to form a high-efficiency composite separation and purification mechanism; like Figure 2 As shown in the flue gas running direction, a water flow chamber 3 is provided in the partition plate 1, and water in the opposite direction to the flue gas running is introduced into the water flow chamber 3. With the change of water flow and the parallel heat interaction of multiple units, the flue gas is fully cooled. The cooling process is not limited by the traditional flue gas condensation dew point. The treated flue gas temperature breaks through the original exhaust temperature of more than 120°C and reaches a temperature level that is only 5-10°C higher than the inlet water temperature. At the same time, the reverse flow of water is heated, which lays the foundation for overcoming the limitation of flue gas emission temperature from this perspective. like Figure 3 The flow direction of flue gas and water in the flue shown in the figure, the complex multiphase flow flue gas collides with the oncoming wall, after being fully cooled, once the flue gas temperature is lower than the acid condensation temperature and the dew point temperature, the acid vapor and water vapor in the flue gas will condense on the surface of multiple sets of parallel W-type unit treatment channels 2, and the condensed liquid and the dust particles and tar particles in the flue gas are captured by the wall of the partition plate 1, and flow to the bottom of the flue along the wall under the action of gravity, and converge into the separation chamber 5 from the flue bottom plate 4. Considering the flow direction of the flue gas through the exclusive process design, the periodic changes generated according to the requirements form a sufficient cooling and inertial separation mechanism for the flue gas with complex components and phases; after the cooling phase change, it is captured twice by the efficient wall in the W-type unit treatment channel 2, and the gas mixture is liquefied and separated, which plays a comprehensive role in waste heat utilization and efficient separation of dust, tar and condensed acid.

[0034] Furthermore, the partition plates 1 are arranged in parallel and periodically, and the flue bottom plate 4 is arranged to be tilted downward along the flue gas flow direction, so that the separated dust particles and condensed liquid can be converged to the bottom of the separation bin 5 under the action of gravity. Multiple groups of partition plates 1 are arranged in parallel and periodically, and multiple groups of partition plates 1 form multiple groups of parallel W-shaped unit processing channels 2 in the flue. Both sides of each section of the wall exchange heat with the flue gas, and the flue gas will be efficiently and fully cooled, and the goal of fully utilizing the waste heat of the flue gas can be achieved based on this; at the same time, considering the material of multiple groups of parallel W-shaped unit processing channels 2, the flue gas is cooled to an end difference of only 5-10°C higher than the inlet water temperature, which fundamentally breaks through the problem that the waste heat of traditional flue gas is limited by the condensation temperature. While breaking through the bottleneck of traditional flue gas cooling, it lays the foundation for a substantial increase in the life of subsequent flue gas treatment bag dust removal and acid removal.

[0035] Each group of parallel W-shaped unit processing channels 2 forms multiple processing units through secondary flow surfaces and upstream walls. Each processing unit includes a group of secondary flow surfaces and upstream walls adjacent to them. Multiple processing units realize periodic changes in the flow direction of the flue gas. The W-shaped unit processing channel 2 also includes a horizontally arranged inlet surface and an outlet surface. The inlet surface and the outlet surface are distributed and connected to the secondary flow surfaces. The flue gas flows from the inlet surface through the W-shaped unit processing channel 2 to the outlet surface. This special design fully cools and inertially separates the flue gas with complex components and phases, but efficiently captures the wall after phase change to liquefy and separate the gas mixture, thereby achieving the comprehensive effects of waste heat utilization and efficient separation of dust, tar and condensed acid, and can achieve the dual goals of inertial separation and enhanced heat exchange.

[0036] Example 3

[0037] A cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization, through specially designed, parallel and periodically arranged partition plates 1, a plurality of parallel W-shaped unit treatment channels 2 are formed in the flue, the plurality of parallel W-shaped unit treatment channels 2 include secondary flow surfaces and oncoming wall surfaces alternately arranged, and an angle is formed between the secondary flow surfaces and the oncoming wall surfaces, such as Figure 1 As shown, in the device using the cooling and separation integrated multi-unit treatment method, the flue is divided by parallel and periodically arranged partition plates 1, and multiple groups of parallel W-shaped unit treatment channels 2 are formed in the flue. While the complex multiphase flow flue gas bends and flows in the multiple groups of parallel W-shaped unit treatment channels 2, it is fully cooled to form a high-efficiency composite separation and purification mechanism; like Figure 2As shown in the flue gas running direction, a water flow chamber 3 is provided in the partition plate 1, and water in the opposite direction of the flue gas running is introduced into the water flow chamber 3. With the change of water flow and the parallel heat interaction of multiple units, the flue gas is fully cooled. The cooling process is not limited by the traditional flue gas condensation dew point. The treated flue gas temperature breaks through the original exhaust temperature of more than 120°C. The flue gas is fully cooled to a temperature level that is only 5-10°C higher than the inlet water temperature. At the same time, the water in the reverse flow is heated, which lays the foundation for overcoming the limitation of flue gas emission temperature from this perspective. like Figure 3 The flow direction of flue gas and water in the flue shown in the figure, the complex multiphase flow flue gas collides with the oncoming wall, after being fully cooled, once the flue gas temperature is lower than the acid condensation temperature and the dew point temperature, the acid vapor and water vapor in the flue gas will condense on the surface of multiple sets of parallel W-type unit treatment channels 2, and the condensed liquid and the dust particles and tar particles in the flue gas are captured by the wall of the partition plate 1, and flow to the bottom of the flue along the wall under the action of gravity, and converge into the separation chamber 5 from the flue bottom plate 4. Considering the flow direction of the flue gas through the exclusive process design, the periodic changes generated according to the requirements form a sufficient cooling and inertial separation mechanism for the flue gas with complex components and phases; after the cooling phase change, it is captured twice by the efficient wall in the W-type unit treatment channel 2, and the gas mixture is liquefied and separated, which plays a comprehensive role in waste heat utilization and efficient separation of dust, tar and condensed acid.

[0038] Furthermore, the partition plates 1 are arranged in parallel and periodically, and the flue bottom plate 4 is arranged to be tilted downward along the flue gas flow direction, so that the separated dust particles and condensed liquid can be converged to the bottom of the separation bin 5 under the action of gravity. Multiple groups of partition plates 1 are arranged in parallel and periodically, and multiple groups of partition plates 1 form multiple groups of parallel W-shaped unit processing channels 2 in the flue. Both sides of each section of the wall exchange heat with the flue gas, and the flue gas will be efficiently and fully cooled, and the goal of fully utilizing the waste heat of the flue gas can be achieved based on this; at the same time, considering the material of multiple groups of parallel W-shaped unit processing channels 2, the flue gas is cooled to a terminal difference of only 5-10°C higher than the inlet water temperature, which fundamentally breaks through the bottleneck of the traditional flue gas waste heat being limited by the condensation temperature, and at the same time lays the foundation for a substantial increase in the life of subsequent flue gas treatment (bag dust removal, acid removal).

[0039] Each group of parallel W-shaped unit processing channels 2 forms multiple processing units through secondary flow surfaces and upstream walls. Each processing unit includes a group of secondary flow surfaces and upstream walls adjacent to them. Multiple processing units realize periodic changes in the flow direction of the flue gas. The W-shaped unit processing channel 2 also includes a horizontally arranged inlet surface and an outlet surface. The inlet surface and the outlet surface are distributed and connected to the secondary flow surfaces. The flue gas flows from the inlet surface through the W-shaped unit processing channel 2 to the outlet surface. This special design fully cools and inertially separates the flue gas with complex components and phases, but efficiently captures the wall after phase change to liquefy and separate the gas mixture, thereby achieving the comprehensive effects of waste heat utilization and efficient separation of dust, tar and condensed acid, and can achieve the dual goals of inertial separation and enhanced heat exchange.

[0040] The partition plate 1 is made of corrosion-resistant and heat-conductive material, and the heat recovery effect is determined by the material selection of the partition plate 1. While fundamentally ensuring sufficient cooling of the flue gas, it cooperates with multiple sets of parallel W-shaped unit processing channels 2 to efficiently achieve cooling and separation of multi-phase flue gas; specifically, the partition plate 1 is fluoroplastic, preferably polytetrafluoroethylene; its pipe diameter is 3mm-6.4mm.

[0041] like Figure 4 As shown, the upper part of the separation bin 5 is connected to the flue, and its bottom is conical. The separated dust particles and condensed liquid particles converge to the bottom of the separation bin 5 under the action of gravity. The bottom of the separation bin 5 is equipped with an external compressed air and water flow purge system for sweeping the air out, so as to purge the dust particles and condensed liquid particles converging to the bottom of the separation bin 5 outward. The flue bottom plate 4, the partition plate 1 and the separation bin 5 are detachably connected, which is a standard structure that is convenient for cleaning and detachable replacement. The number and parameters of the units are adjusted according to the actual flue gas flow rate to be processed.

[0042] The traditional waste heat utilization device mentioned above is a heat recovery system based on carbon steel pipes. A major problem that hinders long-term stable heat exchange in this tubular system is the accumulation of tar and particulate matter on the heat exchange surface. This is an intuitive result of the combined effect of the structure, materials, flue gas components and heat exchange corresponding flue gas side flow of this heat exchanger. Moreover, this method cannot be cleaned efficiently, that is, there is a problem of hindering the continuous and stable heat exchange, which increases the difficulty of manual cleaning and maintenance, and the system operation cost is bound to remain high.

[0043] In order to fundamentally solve the above problems, the present invention constructs an efficient countercurrent heat exchange mechanism from the perspective of flow heat exchange. The flue gas flows into a plurality of specially designed parallel flues from the left inlet at the corresponding pressure, temperature and flow rate. The adjacent parallel flues are separated by a partition plate 1, which is the outer wall of the cavity for heating water. It is equivalent to the flue gas going outside the partition plate 1 and the water going in reverse to the plate heat exchanger inside the partition plate 1. When the flue gas flows through the flue, the reverse-flowing water is heated based on the principle of the plate heat exchanger.

[0044] The mechanism of this flow organization and heat exchange enhancement system is: 1. Select the appropriate material. The heat exchanger adopts the first point of setting a series of parallel plate heat exchangers along the gravity direction, which greatly reduces the probability of accumulation of particles and tar-like substances to pollute the heat exchange surface. The material and surface characteristics of the parallel plate combined heat exchanger make it difficult for pollutants to adhere. At the same time, since the plate body is set along the gravity direction, the pollutants that cannot adhere will settle to the bottom due to the action of gravity; 2. The material of the bottom and the flue gas flow direction are designed exclusively along the slope, which lays the physical and flow boundary foundation for the pollutants settled at the bottom to be effectively cleaned up by the flue gas under the dual action of gravity and airflow shear. The bottom material is also made of the same material as the heat exchanger. The smooth plate surface can even be made into a plate heat exchanger to reduce the probability of pollutant attachment; 3. Control of flue gas residence time and secondary flow organization to enhance heat exchange. The W-type unit processing channel 2 designed exclusively by the present invention directly controls the flow direction of the flue gas, thereby effectively optimizing the residence time of the flue gas in the corresponding section and providing a basic guarantee for sufficient heat exchange; this specially designed flue can well control the flow direction of the flue gas. During each heat exchange process of the periodic oncoming wall, the flue gas is blocked by the wall. The corresponding flow characteristics have a certain restraining effect on the main flow of the corresponding flue gas flow direction. The flue gas will directly form an impact in the corresponding flow direction, destroying the heat exchange boundary layer to enhance heat exchange; and the periodic parallel side wall will form vortices of different scales of periodic secondary flow due to the change of the flow boundary. While breaking the heat exchange boundary layer on this surface, the flue gas heat is effectively brought into the wall exchange area. This is the basic feature of flow control to enhance heat exchange. This exclusive W-type unit processing channel design is that the oncoming wall and the parallel surface will undergo periodic adjustments to ensure the adequacy of the heat exchange effect. This is something that the traditional tube-in-tube system cannot achieve; 4. The flow resistance is controllable. The biggest difference from the traditional tube-in-tube system is that the traditional tube-in-tube system uses an array of pipes to enhance heat exchange based on the periodic secondary flow generated by the flue gas bypassing the front array of pipes. This heat exchange method will cause a series of problems such as difficult to control heat exchange and large flow resistance. Pollution accumulation will inevitably be passively affected by this flow, forming different accumulation states in different parts, causing typical problems of uneven local heating, and causing a series of problems: safety, heat exchange efficiency, and difficult cleaning and maintenance. The present invention overcomes the above problems from various aspects such as structure, material, and airflow organization.

[0045] The outer wall of the plate heat exchanger is made of corrosion-resistant materials such as tetrafluoroethylene, which has good heat exchange capacity. When the flue gas flows through the flue, as a heating source, condensation and acid will occur in different parts due to the water temperature. In this way, when taking heat, the choice of the material of the partition plate 1 determines the depth of waste heat recovery. For the flow of water, the heat exchange is carried out on the entire plane, and the acid corrosion can be naturally shielded due to the choice of material. The treated flue gas temperature has greatly exceeded the limitation of the original exhaust temperature of more than 120°C. The flue gas is fully cooled to a temperature level that is only 5-10°C higher than the inlet water temperature, and the flue gas is fully cooled.

[0046] Compared with metal stainless steel, fluoroplastic polytetrafluoroethylene can effectively solve the problem of low-temperature corrosion. Its physical and chemical properties are stable, high temperature and low temperature resistance, its surface is smooth, free energy is relatively low, friction resistance is small, it is not easy to scale and has good corrosion resistance, especially at low speed and high load, its friction coefficient can be as low as 0.04. Since the thermal conductivity of fluoroplastics is only 0.18~0.24W / m·K, the thermal conductivity is poorer than that of metal materials. Thin-walled small-diameter tubes are used as much as possible, and the diameter range is generally between 3mm-6.4mm. This can not only greatly reduce the thermal resistance of the tube wall, but also achieve a larger heat transfer area in the same volume. Although the cost is higher than that of metal low-temperature economizers, it can utilize more flue gas waste heat and has a long life, and the economic benefits of long-term use are very significant.

[0047] For the present invention, under the corresponding heat exchanger material and layout conditions, with the specially designed sedimentation separation section, under the premise of ensuring heat exchange efficiency, the flue gas can theoretically be cooled to the temperature corresponding to the minimum end difference based on the inlet water temperature. This is something that cannot be achieved by using traditional flue gas waste heat. A conical mode is adopted at the bottom of the sedimentation separation section, and a certain purge or washing device can be set to collect and discharge the separated pollutants from the bottom.

[0048] The present invention can control the flow direction of the flue gas in the flue. Under the guidance of the wall of the heat exchanger, the flow direction of the flue gas changes periodically. An intuitive effect of this change is that by changing the direction of the flue gas flow, the dust and oil particles with relatively poor followability in the flue gas are separated by inertial separation, so that the dust removal and oil removal of the flue gas are enhanced based on flow control.

[0049] In order to recover the waste heat of flue gas from coal-fired boilers to the greatest extent, another important starting point of the present invention is to efficiently remove the acid vapor and water vapor components in the flue gas to achieve the deacidification and dehumidification of the flue gas. According to the aforementioned exclusive countercurrent heat exchange and dust removal coupling method, while completing heat exchange and dust removal, when the surface temperature of the heat exchanger is lower than the acid condensation dew point and the water condensation dew point, the two dew points are different, so the condensation sites are also different. A considerable part of the acid vapor and water vapor condenses, and at the same time plays a dual role in flue gas desulfurization and dehydration. The structure constructed by the present invention has the following values ​​in terms of acid condensation and dehumidification: 1. The flue gas treatment is unitized. Through the designed plate heat exchange flue, the flue gas flow is divided into corresponding periodic treatment units, so that the probability of the flue gas having full contact with the plate heat exchanger is greatly improved. On the one hand, the dust removal and hot water heating effects are optimized. At the same time, due to the enhanced heat exchange, the hot flue gas in each unit is repeatedly fully interacted with the wall of the heat exchanger through the flow organization, and the cooling efficiency is greatly improved, thereby providing more efficient flow field conditions for condensing acid and water; 2. Efficient coupling of heat exchange, condensation and capture of the plate heat exchanger; this means that after the flue gas is in the periodic flue, after the heat exchange is enhanced, the acid and water vapor in the flue gas will gradually condense into particles of different sizes. These particles will be well captured by the wall of the heat exchanger together with the dust particles and tar particles through the inertial separation as mentioned above, and will flow to the bottom of the flue along the wall of the plate heat exchanger under the action of gravity, and will gradually merge into the separator at the outlet end through the action of gravity and flue gas purge. 3. Adjustable periodic unit design to remove separable condensed particles and dust particles to the maximum extent. The structural parameters of the above periodic units can be tailored to different conditions to remove small particles with strong followability of various separable components in the flue gas to the maximum extent, and then be separated and captured by subsequent dust collectors, such as bag dust collectors. From this perspective, the operating efficiency of the subsequent dust filtration system can be guaranteed, and the operating life can be extended accordingly.

[0050] When the separation efficiency is improved, the separated dust particles and condensed liquid particles will gather to the lower part of the entire cavity under the action of gravity. In order to improve the self-purification ability of the system and avoid the accumulation of impurities in the lower part of the cavity, the lower wall of the flue is sloped along the direction of the flue gas flow at a certain angle θ, such as Figure 5 As shown in the figure, the shearing force of the flue gas flow is used to clean the dust particles at the bottom. At the same time, this slope can use gravity to collect the condensed liquid along the flue gas flow direction. A special separation bin 5 is designed at the end of the flue, and the dust particles and condensed liquid converge to the bottom of the separation bin 5. The bottom of the separation bin 5 can be designed to be conical and equipped with an external compressed air and water flow purge system for air flow sweeping.

[0051] For the flue gas heat exchange process, due to the complex characteristics of the flue gas itself, even with the efficient treatment process with the above characteristics, as the treatment time increases, from the perspective of the total amount, especially considering the sticky characteristics of tar substances themselves, the final collected pollution complex still has the potential problem of local sticky adhesion and accumulation. From this perspective, the present invention utilizes a series of encapsulated detachable unit modules to form an efficient mechanism for regular cleaning of different parts. Of course, the subsequent airflow organization system must also be adjusted. The different plate heat exchangers of each modular unit are designed as a standard structure that can be detached and replaced, so that local replacement can be carried out to reduce the overall operation and maintenance costs. In the corresponding unit module, the installation angle and relative distance of the plate heat exchanger can be adaptively designed and adjusted according to the actual situation of the flue gas, under the conditions of optimizing resistance loss, optimizing heat exchange effect, and reasonable investment; The present invention achieves the comprehensive effects of waste heat utilization and efficient separation of dust, tar and condensed acid through exclusive process design, sufficient cooling and inertial separation of flue gas with complex components and phases, and efficient wall capture after phase change to liquefy and separate the gas mixture. It specifically solves 1) the problem that waste heat cannot be fully utilized due to condensed acid corrosion in flue gas, 2) dust and tar substances in flue gas are effectively separated through specially designed airflow organization mode, thus reducing the burden of subsequent processing and extending the life of subsequent equipment; 3) the multi-unit processing mode with adjustable number greatly improves the processing and heat exchange efficiency. The method of the present invention achieves waste heat utilization and at the same time, the temperature of the treated flue gas breaks through the limitation of the original exhaust temperature of more than 120°C. The flue gas is fully cooled to a temperature level that is only 5-10℃ higher than the inlet water temperature; at the same time, the counter-flowing water is heated, which lays the foundation for overcoming the temperature limitation of flue gas emission, and realizes the efficient separation of solid particles such as dust and tar in the flue gas mixture, and the separation of condensed acids such as acid vapor and water vapor in the flue gas. It achieves the comprehensive effects of liquid condensation, liquid separation and solid separation in the heat exchange system, providing a new idea for the utilization of flue gas waste heat and efficient flue gas treatment.

[0052] The above description is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization, characterized in that: Through specially designed partition plates (1) arranged in parallel and periodically, multiple groups of parallel W-shaped unit processing channels (2) are formed in the flue. The multiple groups of parallel W-shaped unit processing channels (2) include secondary flow surfaces and oncoming wall surfaces arranged alternately, and an angle is formed between the secondary flow surfaces and the oncoming wall surfaces. While the complex multiphase flow flue gas bends and flows in the multiple groups of parallel W-shaped unit processing channels (2), it is fully cooled to form a high-efficiency composite separation and purification mechanism. A water flow chamber (3) is provided in the partition plate (1), and water in the opposite direction to the flow of the flue gas is introduced into the water flow chamber (3). The flue gas is fully cooled by combining the change of water flow with the heat interaction of multiple units in parallel. The cooling process is not limited by the acid condensation dew point of the conventional flue gas. The temperature of the treated flue gas exceeds the original limit of the exhaust temperature of more than 120°C and is fully cooled to a temperature level that is only 5-10°C higher than the inlet water temperature. At the same time, the water in the reverse flow is heated, laying a foundation for overcoming the limit of the flue gas exhaust temperature. The complex multiphase flue gas collides with the oncoming wall. After being fully cooled, once the flue gas temperature is lower than the acid condensation temperature and the dew point temperature, the acid vapor and water vapor in the flue gas will condense on the surface of multiple sets of parallel W-shaped unit processing channels (2). The condensed liquid and the dust particles and tar particles in the flue gas are captured by the wall of the partition plate (1) and flow along the wall to the bottom of the flue under the action of gravity. They are then converged into the separation chamber (5) through the flue bottom plate (4). The flow direction of the flue gas is considered through a dedicated process design, and the periodic changes generated according to the requirements form a sufficient cooling and inertial separation mechanism for the flue gas with complex components and phases. After cooling and phase change, the gas is captured again on the efficient wall surface in the W-shaped unit processing channel (2), and the gas mixture is liquefied and separated, which plays a comprehensive role in waste heat utilization and efficient separation of dust, tar and condensed acid.

2. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: The partition plates (1) are arranged in parallel and periodically, and the flue bottom plate (4) is arranged to be inclined downward along the flue gas flow direction, so that the separated dust particles and condensed liquid can flow to the bottom of the separation bin (5) under the action of gravity.

3. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: Multiple groups of periodically arranged partition plates (1) are provided, and the multiple groups of partition plates (1) form multiple groups of parallel W-shaped unit treatment channels (2) in the flue. Both sides of each wall section exchange heat with the flue gas, and the flue gas is efficiently and fully cooled, thereby achieving the goal of fully utilizing the flue gas waste heat. At the same time, considering the material of the multiple groups of parallel W-shaped unit treatment channels (2), the flue gas is fully cooled to a terminal difference of only 5-10°C higher than the inlet water temperature, fundamentally breaking through the bottleneck of the traditional flue gas waste heat being limited by the condensation temperature, and at the same time laying the foundation for a substantial increase in the subsequent flue gas treatment life.

4. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: Each group of parallel W-shaped unit processing channels (2) forms a plurality of processing units through the secondary flow surface and the oncoming wall surface, and the cooling and separation of the flue gas are efficiently promoted; each processing unit includes a group of secondary flow surfaces and the oncoming wall surface adjacent thereto, and the plurality of processing units realizes a periodic change in the flow direction of the flue gas.

5. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: The multiple sets of parallel W-shaped unit processing channels (2) further include an inlet surface and an outlet surface arranged horizontally, and the inlet surface and the outlet surface are distributed and connected with a secondary flow surface, and the smoke flows from the inlet surface into the multiple sets of parallel W-shaped unit processing channels (2) and flows out from the outlet surface.

6. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: The partition plate (1) is made of a corrosion-resistant and heat-conductive material, so that the heat recovery effect is determined by the material selection of the partition plate (1). While fundamentally ensuring that the flue gas is fully cooled, it cooperates with multiple sets of parallel W-shaped unit processing channels (2) to efficiently achieve the cooling and separation of multi-phase flue gas.

7. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 6 is characterized in that: The partition plate (1) is made of fluoroplastic, preferably polytetrafluoroethylene; its corresponding wall thickness is 3 mm-6.4 mm.

8. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 1 is characterized in that: The upper part of the separation chamber (5) is connected to the flue, and the bottom of the separation chamber (5) is conical. The separated dust particles and condensed liquid particles flow to the bottom of the separation chamber (5) under the action of gravity.

9. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 8, characterized in that: The bottom of the separation bin (5) is equipped with an external compressed air and water purge system for sweeping out the air flow, so as to blow out the dust particles and condensed liquid particles that converge at the bottom of the separation bin (5).

10. The cooling and separation integrated multi-unit treatment method for flue gas waste heat utilization according to claim 9, characterized in that: The flue bottom plate (4), the partition plate (1) and the separation chamber (5) are detachably connected, and the standard structure is convenient for cleaning and detachable replacement. The number and parameters of the units are adjusted according to the actual flue gas flow rate to be processed.

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