A rotary kiln flue gas purification and waste heat recovery device and method

Abstract

The present invention relates to the technical field of rotary kiln flue gas treatment and heat recovery, and more specifically, to a rotary kiln flue gas purification and waste heat recovery device and method, comprising a purification and heat transfer device, the purification and heat transfer device comprising a device body, a primary heat transfer element disposed within the device body, an air inlet chamber disposed in the middle of the primary heat transfer element, the air inlet chamber having an inverted conical chamber structure; an air inlet port disposed at the upper end of the air inlet chamber, a first settling chamber disposed at the lower end thereof, a first sealing plug removably disposed at the lower end of the first settling chamber; a first spiral fluid chamber disposed within the primary heat transfer element, a plurality of first vents disposed between two adjacent spiral chambers; the first spiral fluid chamber having a first fluid inlet and a first fluid outlet. The invention utilizes a method of directly mixing high-speed circulating fluid and cold fluid to enhance heat transfer efficiency. The invention can significantly enhance solid waste settling efficiency, improve purification efficiency, and achieve high waste heat recovery efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of rotary kiln flue gas treatment and heat recovery, and in particular to a rotary kiln flue gas purification and waste heat recovery device and method. Background Art

[0002] Rotary kilns, as core high-temperature calcining equipment in industries such as cement, metallurgy, and chemicals, generate large amounts of high-temperature exhaust gas during operation. This high-temperature exhaust gas not only contains a large amount of heat, but also pollutants such as dust, sulfur oxides (SOx), nitrogen oxides (NOx), heavy metals, and volatile organic compounds (VOCs). Therefore, this also poses technical challenges for rotary kiln flue gas purification and waste heat recovery. Currently, exhaust gas purification and heat recovery are achieved using two sets of equipment, for example: bag filters are commonly used, and heat recovery uses waste heat boilers or heat pipe heat exchangers. Bag filters not only have high operating resistance and high energy consumption, but also have a strong dependence on cleaning and a short filter bag life. Heat pipe heat exchangers have low heat exchange efficiency, especially after three months of operation, when dust deposition easily causes an efficiency drop of 15% to 20%. Summary of the Invention

[0003] The present invention provides a rotary kiln flue gas purification and waste heat recovery device and method to solve the above-mentioned background technical problems and achieve preliminary purification of rotary kiln flue gas and efficient recovery of waste heat.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A rotary kiln flue gas purification and waste heat recovery device includes a purification and heat transfer device and a fluid mixing device. The purification and heat transfer device includes a device body, a first-level heat transfer body is provided in the device body, an air inlet cavity is provided in the middle of the first-level heat transfer body, and the air inlet cavity has an inverted cone chamber structure; an air inlet is provided at the upper end of the air inlet cavity, and a first sedimentation chamber is provided at the lower end thereof, and a first sealing plug is removably provided at the lower end of the first sedimentation chamber; a first spiral fluid cavity is provided inside the first-level heat transfer body, and a plurality of first air vents are provided between two adjacent threaded cavities thereof; the first spiral fluid cavity is provided with a first fluid inlet and a first fluid outlet.

[0006] Optionally, the first ventilation hole is arranged to be inclined from the inside to the outside.

[0007] Optionally, a secondary heat transfer body is further provided on the periphery of the primary heat transfer body, and an air collecting chamber is provided between the secondary heat transfer body and the primary heat transfer body; a second spiral fluid cavity is provided inside the secondary heat transfer body, and a plurality of second air vents are provided between two adjacent threaded cavities; the second spiral fluid cavity is provided with a second fluid inlet and a second fluid outlet.

[0008] Optionally, the second vent hole is arranged to be inclined from the inside to the outside.

[0009] Optionally, a second sedimentation chamber is provided at the lower portion of the gas collecting chamber; and a second sealing plug is detachably provided at the lower end of the second sedimentation chamber.

[0010] Optionally, a shell is further provided on the periphery of the secondary heat transfer body, an exhaust cavity is provided between the shell and the secondary heat transfer body, an exhaust port is provided at the upper end of the exhaust cavity, and a third sedimentation chamber is provided at the lower end thereof; a third sealing plug is removably provided at the lower end of the third sedimentation chamber.

[0011] Optionally, a fluid mixing device is further included, which includes a lower mixing chamber and an upper mixing chamber; the lower mixing chamber is provided with a circulating fluid inlet and a cold fluid inlet; the upper mixing chamber is provided with a circulating fluid outlet and a fluid supply outlet.

[0012] Optionally, a partition is provided between the lower mixing chamber and the upper mixing chamber; and a plurality of through holes are provided on the partition.

[0013] Optionally, the partition is arranged at an angle.

[0014] A method for purifying flue gas and recovering waste heat from a rotary kiln comprises using the above-mentioned device for purifying flue gas and recovering waste heat from a rotary kiln, and further comprising:

[0015] (1) By using a high-speed circulating fluid to pass into the purification and heat transfer device, the heat exchange efficiency with the exhaust gas is improved;

[0016] (2) Relying on the high-efficiency heat absorption achieved in (1), the heat of the exhaust gas is reduced, thereby improving the sedimentation of solid waste such as dust in the exhaust gas;

[0017] (3) By using a fluid mixing device, the cold fluid is directly mixed with the high-temperature, high-speed circulating fluid in (1) to form a mixed hot fluid, thereby improving the heat transfer efficiency between the cold and hot fluids, and realizing partial output of the mixed hot fluid, thereby realizing the output and utilization of the waste gas heat.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The flue gas purification and waste heat recovery device of the present invention is provided with an air intake cavity with an inverted cone chamber structure. Air is taken in from the top, which causes the lower airflow to shrink, which is conducive to the collision of solid waste particles such as dust and agglomeration into large agglomerated particles. Combined with the first air vent provided with a first-level heat transfer body for cooling and inclined upward from the inside to the outside, it is conducive to the exhaust gas changing from the original downward flow direction to the inclined upward flow direction in the first air vent, slowing down the air flow velocity, and increasing the heat exchange time of the high-temperature exhaust gas in the first air vent, which makes it easier to settle out solid waste such as dust in the first air vent due to the rapid drop in exhaust gas temperature and the relatively decreased flow velocity, and fall into the first settling chamber from the inclined first air vent. Compared with bag filtration, the aperture of the first air vent is larger and not easy to be blocked. The flue gas solid waste is mainly settled by fluid deceleration and cooling.

[0020] 2. The spiral fluid cavity is arranged inside the heat transfer body, which can meet the high flow rate of the circulating fluid in the spiral fluid cavity. Compared with traditional heat exchange tubes, it is less likely to experience high-frequency vibration. By increasing the flow rate of the circulating fluid, the temperature difference between the fluid and the heat transfer body is increased. At the same time, a number of first vents are penetratingly arranged in the heat transfer body to increase the contact area between the exhaust gas and the heat transfer body, thereby improving the heat conduction efficiency of the circulating fluid.

[0021] 3. Directly mix the cold fluid with the circulating fluid to obtain a mixed hot fluid, which significantly improves the heat exchange efficiency, and directly guides the unmixed hot fluid to utilize the heat source, significantly improving the waste gas heat utilization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0023] Figure 1 It is a schematic structural diagram of the purification and heat transfer device of the present invention;

[0024] Figure 2 is a schematic diagram of the fluid flow of the purification and heat transfer device of the present invention;

[0025] Figure 3 It is a schematic structural diagram of the fluid mixing device of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "inside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0028] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, or electrical connections; direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0029] like Figures 1-2 As shown, a rotary kiln flue gas purification and waste heat recovery device includes a purification and heat transfer device, which includes a device body 1. A first-stage heat transfer element 3 is disposed within the device body 1. An air inlet chamber 3-1 is disposed in the middle of the first-stage heat transfer element 3. The air inlet chamber 3-1 has an inverted conical chamber structure. An air inlet port 11 is disposed at the upper end of the air inlet chamber 3-1, which is connected to the rotary kiln flue gas outlet through an air inlet pipe 10. A first settling chamber 22 is disposed at the lower end of the air inlet chamber 3-1. A first sealing plug (not shown) is removably disposed at the lower end of the first settling chamber 22. The purpose of this design is that waste gas is input from the upper end of the air inlet chamber 3-1 and the space gradually narrows downward, which facilitates the collision and contact between the waste gas and the inner wall of the first-stage heat transfer element 3, and the solid particles in the waste gas are discharged. The particles agglomerate into larger particles due to the relative contraction of the gas, which facilitates the sedimentation of the solid waste. The primary heat transfer element 3 is internally provided with a first spiral fluid chamber 5, with a plurality of first vent holes 7 disposed between two adjacent spiral chambers. In this embodiment, the plurality of first vent holes 7 are arranged at an angle from the inside to the outside, preferably from the inside to the outside. This design facilitates the waste gas from flowing downward in the inlet chamber 3-1 to flowing upward, slowing the flow rate of the waste gas fluid, increasing the contact time between the waste gas and the wall of the first vent hole 7, and improving the heat transfer effect. The high-temperature waste gas cools and contracts, facilitating further sedimentation of the large solid waste particles in the early stage, thereby improving the purification effect. The first spiral fluid chamber 5 is provided with a first fluid inlet 4 and a first fluid outlet 14. In this embodiment, the first spiral fluid chamber 5 is used to allow the introduction of cooling gas, with the circulating gas flowing in through the first fluid inlet 4 and out through the first fluid outlet 14.

[0030] Optionally, a secondary heat transfer body 8 is disposed on the periphery of the primary heat transfer body 3, with an air collecting chamber 8-1 disposed between the secondary heat transfer body 8 and the primary heat transfer body 3. A second spiral fluid chamber 6 is disposed within the secondary heat transfer body 8, with a plurality of second vents 16 disposed between two adjacent threaded chambers. Specifically, the plurality of second vents 16 are also arranged in a spiral arrangement along the gap between the two threaded chambers. The second spiral fluid chamber 6 is provided with a second fluid inlet 17 and a second fluid outlet 9. The second vents 16 are arranged at an inward-outward angle. In this embodiment, they can be arranged to be inclined downward from the inward-outward angle to facilitate a difference in the fluid direction from that of the first vents 7, further reducing the exhaust gas flow rate and improving the solid waste settling effect. Furthermore, in this embodiment, a coolant fluid (such as water) can be introduced into the second spiral fluid chamber 6. Water has a greater specific heat, which facilitates further recovery of heat from the final exhaust gas.

[0031] Optionally, a second settling chamber 21 is provided at the lower portion of the gas collecting chamber 8 - 1 ; a second sealing plug (not shown) in an annular structure is detachably provided at the lower end of the second settling chamber 21 .

[0032] A housing is also provided around the secondary heat transfer element 8. An exhaust chamber 15 is provided between the housing and the secondary heat transfer element 8. An exhaust port 12 is provided at the upper end of the exhaust chamber 15. During use, an exhaust pipe is connected to the exhaust port 12 via a ring connector, allowing access to a subsequent exhaust treatment device. A third settling chamber 20 is provided at its lower end. A third sealing plug (not shown) in a removable annular structure is provided at the lower end of the third settling chamber 20. In some embodiments, a single tower-shaped cover can be used to horizontally position the lower ends of the first, second, and first settling chambers. The tower-shaped cover can then be lifted and tightened to seal the lower ends of all three settling chambers. When cleaning is required, the cover can be opened and cleaned.

[0033] In this embodiment, if Figure 1 As shown, a bracket 19 is provided for supporting the device. At the same time, a plurality of support rods 18 are provided between the primary heat transfer element 3 and the secondary heat transfer element 8. A plurality of second support rods 2 are provided at the lower part of the exhaust cavity 15 between the shell and the secondary heat transfer element 8, and a plurality of third support rods 13 are provided at the upper part.

[0034] In some embodiments, a third-stage heat transfer element may be added to the periphery of the second-stage heat transfer element. Simple extensions and expansions of similar solutions described above in this application fall within the scope of protection of this application.

[0035] Optional, such as Figure 3As shown, it also includes a fluid mixing device 23, which includes a lower mixing chamber 27 and an upper mixing chamber 33; the lower mixing chamber 27 is provided with a circulating fluid inlet 36 and a cold fluid inlet 24; the upper mixing chamber 33 is provided with a total fluid outlet 32, and the total fluid outlet is provided with a circulating fluid outlet 31 and a fluid supply outlet 30 through a tee.

[0036] Optionally, a partition 28 is provided between the lower mixing chamber 27 and the upper mixing chamber 33; the partition is provided with a plurality of through holes 29. In this embodiment, the partition 28 is provided at an angle.

[0037] During use, two sets of the fluid mixing devices 23 are used in this embodiment, one set is used for mixing gas fluids and the other set is used for mixing liquid fluids. The operation method is as follows:

[0038] (1) A fluid mixing device for mixing gas and fluid, wherein the circulating fluid inlet is connected to a circulating return pipe 34 and is pressurized by a first air pump 35 (preferably a frequency-adjustable air pump), and the present invention Figure 1 The first fluid outlet 14 is connected to Figure 2 The circulating fluid outlet 31 in Figure 1 The first fluid inlet 4 is connected; the cooling gas for mixing is Figure 2 The cold fluid inlet 24 in the lower mixing chamber flows in. In this embodiment, by adding a second air pump 26 (preferably a frequency-adjustable air pump), the air inlet of which is connected to the external atmosphere, natural air is pumped into the lower mixing chamber 27 through the air inlet pipe 25, and is directly mixed with the high-temperature gas returning from the circulating fluid inlet 36 to obtain mixed hot air. Then, part of the mixed hot air is circulated back from the circulating fluid outlet 31, and the other part is output from the fluid supply outlet 30. The output hot air can be utilized. For example, the original rotary kiln is blown with room temperature natural air through a blower. This part of the mixed hot air can be blown into the rotary kiln, which can reduce the amount of coal used in the rotary kiln. This part of the hot air can also be used for drying all products in this industry (such as titanium concentrate drying, zircon sand drying, artificial rutile pre-drying, iron oxide drying, etc.), which significantly reduces production costs.

[0039] (2) A fluid mixing device for mixing liquid fluids, which is similar to that described in (1), except that the air pump is replaced by a water pump. Figure 1 The connection ports in the flowmeter are changed accordingly: for example, the first fluid inlet 4 is connected to the second fluid inlet 17; the first fluid outlet 14 is connected to the second fluid outlet 9; and the part of the mixed hot liquid drawn out can be used for: the heat preservation of the iron oxide black reaction tank and the industrial acetic acid storage tank for the rust reaction additive (for example, industrial acetic acid will condense when the temperature is below 16 degrees Celsius, and fluid circulation insulation is required). In the scenario of fluid circulation applied to waste heat utilization, Figure 2The liquid inlet of the second air pump 26 (replaced by the second water pump) can be connected to the circulating fluid outlet of the industrial acetic acid storage tank.

[0040] The above-mentioned air pump and water pump are preferably frequency-adjustable models. In some embodiments, a temperature sensing module can be provided in the lower mixing chamber 27 and the upper mixing chamber 33 to adjust the frequency at the second air pump 26 according to the heat exchange effect, or to adjust the frequency according to the fluid flow rate required by the fluid supply outlet 30 to change the input amount of the cold fluid from the second air pump 26.

[0041] The circulating fluid inlet or the circulating fluid outlet is externally connected to a first fluid pump; the cold fluid inlet or the fluid supply outlet is externally connected to a second fluid pump.

[0042] The first spiral fluid chamber 5 and the second spiral fluid chamber 6 of the present application can be set to a larger cross-section than that of conventional heat exchange tubes, so as to achieve rapid circulation of a larger fluid flux and better heat absorption of the flowing high-temperature exhaust gas; and a fluid mixing device is provided, because the insulation of the equipment at the waste heat utilization end, such as the industrial acetic acid storage tank, the fluid in its insulation pipeline cannot meet the high-flux, high-flow rate environment, or the fluid flow rate of the equipment at the relevant waste heat utilization end needs to be strictly controlled, so by providing the present fluid mixing device 23, the fluid circulation / use environment of multiple / multi-type equipment at multiple waste heat utilization ends is met, and at the same time, the high-flux, high-flow rate use environment of the purification and heat transfer device of the present application is met.

[0043] A method for purifying flue gas and recovering waste heat from a rotary kiln comprises using the above-mentioned device for purifying flue gas and recovering waste heat from a rotary kiln, and further comprising:

[0044] (1) By using high-speed circulating fluid (compared to the existing heat exchange tube fluid flow rate can be increased by 2 to 5 times) to pass into the purification and heat transfer device, the heat exchange efficiency with the exhaust gas is improved; increasing the fluid flow rate is conducive to improving the circulating fluid in the Figure 2 The mixing speed of the medium and cold fluids can be increased, and at the same time, the temperature difference between the circulating fluid and the primary heat transfer body 3 or the secondary heat transfer body 8 can be significantly reduced, thereby improving the heat absorption / heat conduction effect and the cooling effect of the high-temperature exhaust gas.

[0045] (2) Relying on the high-efficiency heat absorption achieved in (1), the heat of the exhaust gas is reduced, thereby increasing the sedimentation of solid waste such as dust in the exhaust gas; that is, the high-speed flow of the circulating fluid - Figure 2 Rapid mixing of the intercooling fluid improves the heat transfer efficiency in the primary heat transfer element 3 or the secondary heat transfer element 8, thereby quickly transferring the heat of the high-temperature exhaust gas and cooling it, which is beneficial to the sedimentation of solid waste particles and improves the purification effect.

[0046] (3) By using a fluid mixing device, the cold fluid is directly mixed with the high-temperature, high-speed circulating fluid in (1) to form a mixed hot fluid, thereby improving the heat transfer efficiency between the cold and hot fluids, and realizing partial output of the mixed hot fluid, thereby realizing the output and utilization of the waste gas heat.

Claims

1. A rotary kiln flue gas purification and waste heat recovery device, characterized by: The device comprises a purification and heat transfer device and a fluid mixing device. The purification and heat transfer device comprises a device body, a primary heat transfer element disposed within the device body, an air inlet cavity disposed in the middle of the primary heat transfer element, and an inverted conical cavity structure. An air inlet is disposed at the upper end of the air inlet cavity, and a first settling chamber is disposed at the lower end thereof. A first sealing plug is removably disposed at the lower end of the first settling chamber. A first spiral fluid cavity is disposed within the primary heat transfer element, and a plurality of first air vents are disposed between two adjacent spiral cavities. The first spiral fluid cavity is provided with a first fluid inlet and a first fluid outlet. The first vent hole is arranged to tilt upward from the inside to the outside; A secondary heat transfer body is provided on the periphery of the primary heat transfer body, with an air collecting chamber provided between the secondary heat transfer body and the primary heat transfer body; a second spiral fluid cavity is provided inside the secondary heat transfer body, with a plurality of second air vents provided between two adjacent spiral cavities; the second spiral fluid cavity is provided with a second fluid inlet and a second fluid outlet; The second vent hole is arranged to be tilted downward from the inside to the outside; The fluid mixing device comprises a lower mixing chamber and an upper mixing chamber; the lower mixing chamber is provided with a circulating fluid inlet and a cold fluid inlet; the upper mixing chamber is provided with a circulating fluid outlet and a fluid supply outlet.

2. The rotary kiln flue gas purification and waste heat recovery device according to claim 1, characterized in that: A second sedimentation chamber is provided at the lower part of the gas collecting chamber; and a second sealing plug is detachably provided at the lower end of the second sedimentation chamber.

3. The rotary kiln flue gas purification and waste heat recovery device according to claim 1, characterized in that: A shell is further provided on the periphery of the secondary heat transfer element, an exhaust cavity is provided between the shell and the secondary heat transfer element, an exhaust port is provided at the upper end of the exhaust cavity, and a third settling chamber is provided at the lower end thereof; a third sealing plug is detachably provided at the lower end of the third settling chamber.

4. The rotary kiln flue gas purification and waste heat recovery device according to claim 1, characterized in that: A partition is provided between the lower mixing chamber and the upper mixing chamber; and a plurality of through holes are provided on the partition.

5. The rotary kiln flue gas purification and waste heat recovery device according to claim 4, characterized in that: The partition is arranged in an inclined manner.

6. A method for purifying flue gas and recovering waste heat from a rotary kiln, characterized by: The invention comprises a rotary kiln flue gas purification and waste heat recovery device according to any one of claims 1 to 5, and further comprises: (1) By using a high-speed circulating fluid to pass into the purification and heat transfer device, the heat exchange efficiency with the exhaust gas is improved; (2) Relying on the high-efficiency heat absorption achieved in (1), the heat of the exhaust gas is reduced, thereby improving the sedimentation of solid waste in the exhaust gas; (3) By using a fluid mixing device, the cold fluid is directly mixed with the high-temperature, high-speed circulating fluid in (1) to form a mixed hot fluid, thereby improving the heat transfer efficiency between the cold and hot fluids and achieving partial output of the mixed hot fluid, thereby realizing the output and utilization of the exhaust gas heat.

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