Multi-stage heat removal system for mine return air waste heat utilization

Abstract

The utility model belongs to the technical field of mine return air waste heat utilization, and particularly relates to a multistage heat extraction system for mine return air waste heat utilization. A gravity type heat pipe heat exchanger, a dividing wall type heat taking device and an air-air heat exchanger are sequentially arranged on the air returning and inducing duct in the hot air flowing direction, a hot air inlet of the air-air heat exchanger is communicated with the air returning and inducing duct, a hot air outlet of the air-air heat exchanger is communicated with an air returning and exhausting duct, and a cold air inlet of the air-air heat exchanger is communicated with a fresh air inducing duct. A cold air outlet of the fresh air induced air duct is communicated with a fresh air supply duct, a heat absorption section of the gravity type heat pipe heat exchanger is arranged in the return air induced air duct, a heat release section of the gravity type heat pipe heat exchanger is arranged in the fresh air supply duct, and the heat release section of the gravity type heat pipe heat exchanger is arranged on one side of a cold air outlet of the air-to-air heat exchanger. The heat exchanger is simple in structure, low in operation cost and high in heat exchange efficiency.

Description

TECHNICAL FIELD

[0001] The utility model belongs to mine return air waste heat utilization technical field especially relates to a multistage heat extraction system of mine return air waste heat utilization. BACKGROUND

[0002] Under the background of energy saving and emission reduction, mine return air waste heat utilization technology has been fully developed, mine return air has the characteristics of high humidity, large flow and constant temperature, but for the coal mine with low return air temperature and small waste heat resource quantity, the single heat extraction mode has low heat extraction efficiency, large energy consumption and poor heating capacity when recycling the mine return air waste heat, in order to solve the above technical problems, realize the full use of mine return air, the utility model provides a multistage heat extraction system of mine return air waste heat utilization. UTILITY MODEL CONTENTS

[0003] The utility model aims at providing a multistage heat extraction system of mine return air waste heat utilization to solve the above-mentioned problems of prior art.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a multistage heat extraction system of mine return air waste heat utilization, including return air induced draft air duct, one end of return air induced draft air duct is communicated with mine return air outlet, return air induced draft air duct is provided with gravity type heat pipe heat exchanger, partition wall type heat extractor and gas gas heat exchanger in turn along hot air flow direction, and the hot air inlet of gas gas heat exchanger is communicated with return air induced draft air duct, the hot air outlet of gas gas heat exchanger is communicated with return air exhaust air duct, the cold air inlet of gas gas heat exchanger is communicated with fresh air induced draft air duct, the cold air outlet of fresh air induced draft air duct is communicated with fresh air supply air duct, and the heat absorption section of gravity type heat pipe heat exchanger is arranged in return air induced draft air duct, the heat release section of gravity type heat pipe heat exchanger is arranged in fresh air supply air duct, and the heat release section of gravity type heat pipe heat exchanger is arranged on one side of the cold air outlet of gas gas heat exchanger.

[0005] Preferably, return air resistance balance fan is arranged in return air induced draft air duct, and the return air resistance balance fan is arranged in the upwind direction of the heat absorption section of gravity type heat pipe heat exchanger.

[0006] Preferably, fresh air resistance balance fan is arranged in fresh air induced draft air duct.

[0007] Preferably, the partition wall type heat extractor adopts annular fin structure, and the pipe of the partition wall type heat extractor is provided with water solution working medium with a concentration of 15% to 30%.

[0008] Preferably, the upper fin of the heat absorption section of gravity type heat pipe heat exchanger is annular fin structure with low resistance, and the upper fin of the heat absorption section of gravity type heat pipe heat exchanger is corrugated fin structure.

[0009] Preferably, the return air induction air duct and the fresh air supply air duct are provided with an insulation layer on the outer wall.

[0010] Compared with the prior art, the utility model has the advantages and technical effects as follows:

[0011] The multi-stage heat extraction system for mine return air waste heat utilization has the heat absorption section of the gravity type heat pipe heat exchanger to preferentially exchange heat with the mine return air waste heat in the return air induction air duct, and then the waste heat is subjected to secondary heat exchange through the partition wall type heat extractor, the heat exchanged in the partition wall type heat extractor can heat the heat pump system, then the waste heat subjected to the secondary heat exchange is subjected to third heat exchange through the gas-gas heat exchanger, the waste heat subjected to the third heat exchange is basically at normal temperature and is discharged from the return air exhaust air duct, and the fresh air entering the fresh air induction air duct is preliminarily heated through the gas-gas heat exchanger and further obtains heat through the heat release section of the gravity type heat pipe heat exchanger in the fresh air supply air duct, and is finally sent to the shaft for utilization.

[0012] The utility model discloses simple structure, low operating cost, high heat exchange efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without paying the creative labor:

[0014] Fig. 1 It is a structure schematic view of the multi-stage heat extraction system for mine return air waste heat utilization of the utility model:

[0015] Fig. 2 It is a distribution schematic view of the heat absorption section and the heat release section of the gravity type heat pipe heat exchanger in the utility model:

[0016] 1, return air induction air duct, 2, return air resistance balance fan, 3, gravity type heat pipe heat exchanger, 4, partition wall type heat extractor, 5, liquid outlet pipe, 6, liquid inlet pipe, 7, fresh air induction air duct, 8, fresh air resistance balance fan, 9, gas-gas heat exchanger, 10, return air exhaust air duct, 12, fresh air supply air duct, 13, heat absorption section, 14, heat release section. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the scope of the present application.

[0018] In order to make the above-mentioned purposes, features and advantages of the present application more apparent, clear and easy to understand, the present application will be further described in detail below with the drawings and specific embodiments.

[0019] The technical terms in the embodiments are described as follows:

[0020] The gravity heat pipe heat exchanger can be divided into three parts, namely, an evaporation section, an adiabatic section and a condensation section, according to the function along the axial direction. The evaporation section is the part for absorbing heat, the condensation section is the part for releasing heat, and the adiabatic section plays a role of isolating the heat transfer between the evaporation section and the condensation section.

[0021] Working principle:

[0022] Evaporation section heat absorption and vaporization: In the evaporation section, the liquid working medium absorbs heat and changes phase from liquid to gas (steam) after phase change.

[0023] Steam transmission: The generated high-temperature steam freely floats inside the pipe, is transmitted to the condensation section through the intermediate adiabatic section.

[0024] Condensation section heat release and liquefaction: In the condensation section, the high-temperature steam releases heat and changes phase from gas to liquid after phase change.

[0025] Liquid backflow: The condensed liquid falls back to the evaporation section along the pipe wall under the action of gravity.

[0026] This cycle process is repeated continuously to realize continuous heat transfer.

[0027] Characteristics of the gravity heat pipe heat exchanger:

[0028] High-efficiency heat transfer: The gravity heat pipe heat exchanger transfers heat through the phase change of the working medium, and has high heat transfer efficiency.

[0029] Simple structure: Since the gravity heat pipe does not have a capillary core structure inside, its structure is relatively simple, and the manufacturing cost is also relatively low.

[0030] High reliability: The gravity heat pipe heat exchanger does not need external power in the working process, and the working medium circulates by itself, so it has high reliability.

[0031] Directionality: Gravity-type heat pipe heat exchangers can only be applied in gravitational fields, and the evaporation section must be placed below the condensation section.

[0032] Application of Gravity-type Heat Pipe Heat Exchangers

[0033] Gravity-type heat pipe heat exchangers have been widely used in waste heat recovery, solar energy utilization, and geothermal resource utilization due to their high efficiency, simple structure, and high reliability. For example, the one-way heat transfer characteristics of gravity heat pipes are utilized in the oil pipeline in the permafrost zone of Alaska and along the Qinghai-Tibet Railway in China.

[0034] In summary, the working principle of gravity-type heat pipe heat exchangers is to transfer heat through the phase change of working fluid under gravity, with characteristics of high efficiency, simplicity, and reliability, and has been widely applied in various fields.

[0035] A partition heat exchanger, also commonly known as a partition heat exchanger, works mainly on the process of heat exchange between cold and hot fluids through solid walls (heat transfer surfaces). Here is a detailed explanation of the working principle of the partition heat exchanger:

[0036] I. Basic structure:

[0037] A partition heat exchanger is composed of two or more fluid channels separated by solid walls (i.e., heat transfer surfaces). These solid walls are usually made of metal and have good thermal conductivity. Cold and hot fluids flow on both sides of the wall and exchange heat through the wall.

[0038] II. Heat transfer process:

[0039] The heat transfer process of a partition heat exchanger can be divided into the following steps:

[0040] Heat transfer from hot fluid to solid wall:

[0041] During the flow process, the hot fluid transfers its heat to the left side of the solid wall through convection. In this process, the particles inside the hot fluid show violent disturbance like a vortex and move forward in the disturbance. This flow state is called turbulent flow. In the main body of turbulent flow, heat is rapidly transferred by convection, and the temperature drops very little.

[0042] Near the wall, the fluid flow speed decreases, forming a boundary layer. The fluid inside the boundary layer flows parallel to the wall, and this boundary layer is called the laminar inner layer. In the laminar inner layer, heat is transferred to the solid wall by conduction. Since the thermal conductivity of the fluid is much lower than that of the metal, the heat transfer speed in the laminar inner layer is low, and the temperature drop is large.

[0043] Heat conduction in the solid wall:

[0044] Heat is transferred from the left side of the solid wall to the right side through conduction. Since metals have high thermal conductivity, the heat transfer is fast and the temperature drop is small.

[0045] Heat is transferred from the solid wall to the cold fluid:

[0046] Heat is transferred from the right side of the solid wall to the cold fluid through convection. In this process, the particles inside the cold fluid also exhibit turbulent flow, and heat is rapidly transferred through convection, resulting in an increase in temperature.

[0047] Similarly, in the laminar flow of the cold fluid, heat is transferred from the wall to the cold fluid through conduction.

[0048] Three, heat transfer efficiency and influencing factors:

[0049] The heat transfer efficiency of the partitioned heat extractor depends on multiple factors, including:

[0050] Fluid properties: The thermal conductivity, specific heat capacity, density, and viscosity of the fluid all affect the heat transfer efficiency.

[0051] Flow state: The flow state of the fluid (laminar or turbulent) has a significant impact on heat transfer efficiency. The heat transfer efficiency in turbulent flow is usually higher than that in laminar flow.

[0052] Heat transfer area: The larger the heat transfer area, the faster the heat exchange rate, and the higher the heat transfer efficiency.

[0053] Temperature difference: The larger the temperature difference between the hot and cold fluids, the greater the heat transfer driving force, and the higher the heat transfer efficiency.

[0054] Wall material: The better the thermal conductivity of the wall material, the higher the heat transfer efficiency.

[0055] Four, application:

[0056] Partitioned heat extractors are widely used in chemical, petroleum, metallurgical, food, pharmaceutical and other industries. They can be used for heating, cooling, evaporation, condensation and other processes.

[0057] In summary, the working principle of the partitioned heat extractor is to separate the hot and cold fluids through the solid wall and achieve heat exchange through convection and conduction. Its heat transfer efficiency is affected by multiple factors, including fluid properties, flow state, heat transfer area, temperature difference, and wall material. In practical applications, it is necessary to select the appropriate type and parameters of the heat extractor according to the specific process conditions and requirements.

[0058] Gas-gas heat exchanger is a device used to transfer heat in gas flow, its working principle is based on the principle of heat conduction and convection heat transfer. The following is a detailed explanation of the working principle of gas-gas heat exchanger:

[0059] I. Basic Configuration:

[0060] A gas-gas heat exchanger typically consists of multiple tubes or plates that form the heat exchange surface. Inside the heat exchanger, there are usually two separate gas flow paths: the hot source gas flow and the cooling gas flow. As the hot source gas flow and the cooling gas flow pass through the heat exchanger, heat is transferred between them through the heat exchange surface.

[0061] II. Heat Transfer Process:

[0062] Heat Release by Hot Source Gas Flow:

[0063] As the hot source gas flow passes through the heat exchanger, it releases heat that is transferred to the heat exchanger through the heat exchange surface.

[0064] Heat Transfer to Cooling Gas Flow:

[0065] The heat exchanger transfers the received heat to the cooling gas flow. This process is mainly achieved through two ways: convection and conduction.

[0066] Convective Heat Transfer: Heat is transferred through the convective motion between gas fluids. In a gas-gas heat exchanger, the hot source gas flow and the cooling gas flow undergo convective motion near the heat exchange surface, allowing heat exchange to occur.

[0067] Conductive Heat Transfer: Heat is transferred through the walls or plates of the heat exchanger. The heat released by the hot source gas flow is conducted through the walls or plates to the side of the cooling gas flow, allowing heat transfer to occur.

[0068] Heat Absorption by Cooling Gas Flow:

[0069] As the cooling gas flow passes through the heat exchanger, it absorbs the heat transferred from the hot source gas flow, causing its temperature to rise.

[0070] III. Heat Exchange Efficiency:

[0071] The heat exchange efficiency of a gas-gas heat exchanger depends on several factors, including:

[0072] Material and structure of heat exchange surface: The material and structure of the heat exchange surface have a significant impact on heat transfer efficiency. Generally, heat exchange surfaces made of materials with good thermal conductivity (such as copper, aluminum, or stainless steel) can improve heat transfer efficiency.

[0073] Gas flow speed and flow rate: The faster the gas flow speed and flow rate, the faster the heat exchange rate, but it also increases energy consumption and pressure drop.

[0074] Temperature difference: The greater the temperature difference between the hot source gas flow and the cooling gas flow, the greater the heat transfer driving force and the higher the heat transfer efficiency.

[0075] Heat exchanger design: The design of the heat exchanger (such as counter-flow, parallel-flow or cross-flow structural forms) also affects the heat exchange efficiency. Counter-flow heat exchangers can achieve higher thermal efficiency because the flow directions of high-temperature gas and low-temperature gas inside the heat exchanger are opposite, which helps to increase the contact time and area of heat exchange.

[0076] Four, application:

[0077] Gas-gas heat exchangers are widely used in many fields, including:

[0078] Industrial heating: used for heating process gas or reaction medium.

[0079] Air conditioning and cooling systems: used for cooling or adjusting air temperature.

[0080] Gas turbine: used for recovering waste heat from gas turbine exhaust.

[0081] Petroleum chemical industry: recovering heat generated in catalytic cracking, hydrocracking and other reaction processes.

[0082] Electric power: used for waste heat recovery of boiler exhaust gas, etc.

[0083] In summary, the working principle of gas-gas heat exchanger is to exchange heat through the convection and conduction heat transfer process of hot source gas flow and cooling gas flow on the heat exchange surface. Its heat exchange efficiency is affected by many factors, including the material and structure of the heat exchange surface, gas flow speed and flow, temperature difference and heat exchanger design. In actual application, the appropriate heat exchanger type and parameters need to be selected according to the specific process conditions and requirements.

[0084] Referring to Figs. 1-2 The utility model provides a multistage heat taking system of mine return air waste heat utilization, including return air induced draft air duct 1, one end of return air induced draft air duct 1 is connected with mine return air port, return air induced draft air duct 1 is provided with gravity type heat pipe heat exchanger 3, partition wall type heat taking device 4 and gas -gas heat exchanger 9 in proper order along the hot air flow direction, and the hot air import of gas -gas heat exchanger 9 is connected with return air induced draft air duct 1, and the hot air export of gas -gas heat exchanger 9 is connected with return air exhaust air duct 10, and the cold air import of gas -gas heat exchanger 9 is connected with fresh air induced draft air duct 7, and the cold air export of fresh air induced draft air duct 7 is connected with fresh air supply air duct 12, and the heat absorption section 13 of gravity type heat pipe heat exchanger 3 is located in return air induced draft air duct 1, and the heat release section 14 of gravity type heat pipe heat exchanger 3 is located in fresh air supply air duct 12, and the heat release section 14 of gravity type heat pipe heat exchanger 3 is located in one side of the cold air export of gas -gas heat exchanger 9.

[0085] In the embodiment, the air-to-air heat exchanger 9 is composed of a plurality of circular stainless steel light pipes with a diameter of 20 mm. The return air exhaust air duct 10, the return air exhaust air duct 1 and the fresh air supply air duct 12 are connected by galvanized circular air duct structures, and the connection is sealed.

[0086] The heat absorption section 13 of the gravity type heat pipe heat exchanger 3 is arranged to exchange heat with the mine return air waste heat in the return air exhaust air duct 1 first, and then the return air waste heat exchanges heat again in the partition type heat extractor 4. The heat exchanged in the partition type heat extractor 4 can be used to heat the heat pump system. Then, the return air waste heat after the second heat exchange exchanges heat again in the air-to-air heat exchanger 9, and the return air waste heat after the third heat exchange is basically at room temperature and is discharged from the return air exhaust air duct 10. The fresh air entering the fresh air exhaust air duct 7 is preliminarily heated by the air-to-air heat exchanger 9, and further obtains heat in the heat releasing section 14 of the gravity type heat pipe heat exchanger 3 in the fresh air supply air duct 12, and is finally sent to the shaft for use.

[0087] Further, the return air resistance balance fan 2 is arranged in the return air exhaust air duct 1, and the return air resistance balance fan 2 is arranged in the upwind direction of the heat absorption section 13 of the gravity type heat pipe heat exchanger 3.

[0088] The return air resistance balance fan 2 is arranged to accelerate the directional movement of the return air in the return air exhaust air duct 1, and improve the heat exchange efficiency of the heat absorption section 13 of the gravity type heat pipe heat exchanger 3 and the partition type heat extractor 4.

[0089] Further, the fresh air resistance balance fan 8 is arranged in the fresh air exhaust air duct 7.

[0090] The fresh air resistance balance fan 8 is arranged to accelerate the directional movement of the return air in the return air exhaust air duct 1, and improve the heat exchange efficiency of the heat releasing section 14 of the gravity type heat pipe heat exchanger 3 and the air-to-air heat exchanger 9.

[0091] Further, the partition type heat extractor 4 adopts a ring fin structure, and the pipe of the partition type heat extractor 4 is filled with a water solution working medium with a concentration of 15%-30%, wherein the working medium is a glycol water solution.

[0092] Further, the fin on the heat absorption section 13 of the gravity type heat pipe heat exchanger is a low-resistance ring fin structure, and the fin on the heat releasing section 14 of the gravity type heat pipe heat exchanger is a corrugated fin structure.

[0093] By setting the heat-absorbing section 13 of the gravity type heat pipe heat exchanger with low-resistance annular fin structure, the drainage is facilitated and the annular fin can be effectively prevented from being blocked by a large amount of dust mixed in the return air in the return air induction air duct 1; by setting the heat-releasing section 14 of the gravity type heat pipe heat exchanger with corrugated fin structure, considering that the heat-releasing section 14 is arranged in the fresh air supply air duct 12, there is no condensed water and a large amount of dust, the corrugated fin structure can increase the heat exchange area, and the corrugated form can utilize the formed flow to enhance the heat exchange efficiency.

[0094] Further, in order to reduce heat loss, the outer walls of the return air induction air duct 1 and the fresh air supply air duct 12 are each provided with a heat preservation layer.

[0095] The working principle of the multi-stage heat extraction system for mine return air waste heat utilization is as follows:

[0096] In the first stage, the mine return air enters the gravity type heat pipe heat exchanger 3 under the action of the return air resistance balance fan 2 through the return air induction air duct 1, the return air flows across the surface of the heat-absorbing section 13 of the gravity type heat pipe heat exchanger 3, heat is transferred to the working medium in the pipe, the working medium absorbs the mine return air waste heat by phase change, the temperature of the mine return air is reduced, and the first-stage heat extraction is completed.

[0097] In the second stage, the low-temperature ethylene glycol water solution enters the inter-wall type heat extractor 4 through the liquid inlet pipe 6 on the inter-wall type heat extractor 4, the ethylene glycol water solution absorbs the mine return air waste heat through the inter-wall type heat extractor 4, the temperature of the ethylene glycol water solution is increased after absorbing heat, and the ethylene glycol water solution enters the heat pump system through the liquid outlet pipe 5 on the inter-wall type heat extractor 4, and the second-stage heat extraction of the mine return air is realized.

[0098] In the third stage, the fresh air enters the cold air channel of the air-air heat exchanger 9 under the action of the fresh air resistance balance fan 8 through the fresh air induction air duct 7, the fresh air and the return air perform convective heat transfer through the air-air heat exchanger 9, the temperature of the return air is reduced and the return air is discharged through the return air exhaust air duct 10, and the third-stage heat extraction of the mine return air is completed.

[0099] In the fourth stage, after the fresh air absorbs the mine return air waste heat through the air-air heat exchanger 9, the fresh air enters the fresh air supply air duct 12 and performs heat exchange with the heat-releasing section 14 of the gravity type heat pipe heat exchanger 3, the fresh air is heated for the second time, and the fresh air is sent to the shaft for utilization.

[0100] In the description of the utility model, it is understood that the orientation or position relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.

[0101] The above merely provides the preferred embodiment of the application, and not thereby limited thereto; any modification and replacement made under the scope of the application should be covered within the scope of the application.

Claims

1. A multi-stage heat extraction system for mine return air waste heat utilization, characterized in that, The application relates to a mine air heating system, which comprises a return air and air inlet air duct (1), wherein one end of the return air and air inlet air duct (1) is communicated with a mine return air outlet, a gravity type heat pipe heat exchanger (3), a partition wall type heat extractor (4) and a gas-gas heat exchanger (9) are sequentially arranged on the return air and air inlet air duct (1) along a hot air flow direction, a hot air inlet of the gas-gas heat exchanger (9) is communicated with the return air and air inlet air duct (1), a return air and air outlet air duct (10) is communicated with a hot air outlet of the gas-gas heat exchanger (9), a fresh air and air inlet air duct (7) is communicated with a cold air inlet of the gas-gas heat exchanger (9), a fresh air and air outlet air duct (12) is communicated with a cold air outlet of the fresh air and air inlet air duct (7), an endothermic section (13) of the gravity type heat pipe heat exchanger (3) is arranged in the return air and air inlet air duct (1), a heat releasing section (14) of the gravity type heat pipe heat exchanger (3) is arranged in the fresh air and air outlet air duct (12), and the heat releasing section (14) of the gravity type heat pipe heat exchanger (3) is arranged on one side of the cold air outlet of the gas-gas heat exchanger (9).

2. The multi-stage heat extraction system for mine return air waste heat utilization according to claim 1, characterized in that, A return air and air resistance balance fan (2) is arranged in the return air and air inlet air duct (1), and the return air and air resistance balance fan (2) is arranged on an upwind side of the endothermic section (13) of the gravity type heat pipe heat exchanger (3).

3. The multi-stage heat extraction system for mine return air waste heat utilization according to claim 1, characterized in that, A fresh air and air resistance balance fan (8) is arranged in the fresh air and air inlet air duct (7).

4. The multi-stage heat extraction system for mine return air waste heat utilization according to claim 1, characterized in that, The partition wall type heat extractor (4) adopts a ring fin structure, and a water solution working medium with a concentration of 15%-30% is arranged in a pipe of the partition wall type heat extractor (4).

5. The multi-stage heat extraction system for mine return air waste heat utilization according to claim 1, characterized in that, The endothermic section (13) of the gravity type heat pipe heat exchanger is provided with a low-resistance ring fin structure, and the endothermic section (13) of the gravity type heat pipe heat exchanger is provided with a corrugated fin structure.

6. The multi-stage heat extraction system for mine return air waste heat utilization according to claim 1, characterized in that, The return air and air inlet air duct (1) and the fresh air and air outlet air duct (12) are both provided with an outer wall thermal insulation layer.

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