Kiln flue gas waste heat multi-stage utilization system

Abstract

The utility model belongs to the technical field of flue gas waste heat application, and particularly relates to a multistage utilization system for flue gas waste heat of a kiln. The system sequentially comprises a heat exchanger and a lithium bromide heat pump in the flue gas conveying direction. At least a gas channel and a liquid channel which are independent and exchange heat are arranged in the heat exchanger, a gas inlet pipe and a gas outlet pipe are arranged at the two ends of the gas channel respectively, and the gas outlet pipe is connected with an exhaust pipeline; a weak solution pipeline and / or a generator of the lithium bromide heat pump heat / heats fluid in the weak solution pipeline and / or the generator in the mode that heat exchange is conducted between the weak solution pipeline and / or the generator and the exhaust pipeline. Through the combined application of the heat exchanger and the lithium bromide heat pump, the heat recovery range of waste heat recovery is increased, the dependence on an external heat source is further reduced, and the system has the advantages of being simple in layout and long in service life.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the application technical field of flue gas waste heat, specifically relates to a kiln flue gas waste heat multistage utilization system. BACKGROUND

[0002] Kiln is the high temperature smelting preparation process commonly used equipment, kiln usually uses natural gas / air combustion support or natural gas / pure oxygen combustion support, produces a large amount of flue gas in the combustion process, and the heat in the flue gas is considerable.With the continuous strengthening of people's environmental protection concept, at present, in view of the large amount of flue gas produced in the kiln combustion process, metal heat exchanger, waste heat boiler and other heat exchanger equipment are usually used for waste heat utilization, and the flue gas temperature is relatively low after waste heat utilization, and the heat value is not high, so that high-grade heat energy cannot be generated under the condition of non-powered transportation, and the direct discharge mode is usually adopted, thereby causing resource waste to a certain extent.

[0003] The document with the authorized announcement number CN220436822U discloses a flue gas waste heat utilization system, comprising a first heat pump, a second heat pump and a first heat exchanger, the first heat exchanger is used for cooling industrial equipment;The first heat pump is a lithium bromide heat pump cold water unit, the high-temperature flue gas inlet of the first heat pump is communicated with the flue gas outlet of the industrial equipment, the evaporator of the first heat pump is communicated with the first heat exchanger and forms a first loop, the first loop is provided with a first valve, and the evaporator of the first heat pump is also communicated with a factory water mechanism to form a second loop, the factory water mechanism comprises a cooling part and a heating part;The second heat pump is communicated with the first heat exchanger and forms a third loop.The system can recycle the high-temperature flue gas generated by the industrial equipment, and reduce energy consumption and cost.

[0004] However, the device still has the following problems: the heat pump used in the system uses lithium bromide heat pump, and the flue gas outlet of the industrial equipment is directly connected with the high-temperature flue gas inlet of the heat pump in the form of waste heat utilization, and the dust, nitrogen oxides and even sulfides in the flue gas can be accumulated in the heat pump, affecting the service life of the heat pump. UTILITY MODEL CONTENTS

[0005] In view of the above problems, the utility model aims at providing a kiln flue gas waste heat multistage utilization system, which combines the application of heat exchanger and lithium bromide heat pump, increases the heat recovery range of waste heat recovery, further reduces the dependence on external heat source, and has the advantages of simple layout and long service life.

[0006] In order to achieve the above purpose, the technical scheme of the utility model is as follows:

[0007] A kind of kiln flue gas waste heat multistage utilization system, including heat exchanger, lithium bromide heat pump in order along the flue gas conveying direction;At least the gas passage and liquid passage that heat exchanges independently are provided in the heat exchanger, the gas passage both ends are provided with inlet pipe and outlet pipe respectively, the outlet pipe is connected with exhaust pipe line;Weak solution line and / or generator of the lithium bromide heat pump heat the fluid in weak solution line and / or generator by the way of heat exchange with the exhaust pipe line.

[0008] As further preferred of the utility model, still include raw water treatment box, the raw water treatment box is connected with the both ends of liquid passage by outlet pipe and back liquid pipe respectively.

[0009] As further preferred of the utility model, the cooling water line of lithium bromide heat pump is used for controlling the liquid temperature in raw water treatment box by the way of direct communication with the raw water treatment box / back liquid pipe or indirectly exchanging heat with the back liquid pipe.

[0010] As further preferred of the utility model, back liquid pipe is formed with at least parallel internal loop and external loop, the internal loop is used for exchanging heat with the cooling water line of lithium bromide heat pump and is provided with valve on the internal loop.

[0011] As further preferred of the utility model, lithium bromide heat pump is directly / indirectly connected with heating part for providing heat source to the heating part.

[0012] As further preferred of the utility model, the back liquid pipe of raw water treatment box is directly / indirectly connected with the heating part for providing heat source to the heating part.

[0013] As further preferred of the utility model, the cooling water line of lithium bromide heat pump is directly / indirectly connected with cooling part for providing cold source to the cooling part.

[0014] As further preferred of the utility model, still include cooling tower, the cooling tower is used for providing cold source to lithium bromide heat pump.

[0015] As further preferred of the utility model, the cooling tower is also used for providing cold source to the raw water treatment box or the external loop or the cooling part.

[0016] As further preferred of the utility model, still include the denitration device located in the upstream of heat exchanger, the gas outlet of denitration device is connected with inlet pipe.

[0017] The utility model has the advantages that:

[0018] The kiln flue gas waste heat multistage utilization system has the advantages of simple layout, long service life and the like. BRIEF DESCRIPTION OF DRAWINGS

[0019] BRIEF DESCRIPTION OF DRAWINGS Figure 1 It is a structural schematic view of the utility model.

[0020] BRIEF DESCRIPTION OF DRAWINGS Figure 2 It is another structural schematic view of the utility model.

[0021] BRIEF DESCRIPTION OF DRAWINGS: heat exchanger 1, lithium bromide heat pump 2, exhaust pipeline 3, raw water treatment tank 4, cooling tower 5, heat supply part 6, cold supply part 7, denitration device 8;

[0022] Liquid outlet pipe 41, liquid return pipe 42

[0023] Internal circuit 421, external circuit 422. DETAILED DESCRIPTION

[0024] In the description of the utility model, it is understood that the terms "upper", "lower", "inner", "outer", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the utility model product is used, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0025] In addition, the terms "first", "second" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance

[0026] In the description of the utility model, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "provided", "connected" and the like should be understood broadly, for example, "connected" can be fixedly connected, or can be detachably connected, or integrally connected: can be mechanically connected, or electrically connected: can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0027] The embodiment provides a kiln flue gas waste heat multistage utilization system, as shown in the accompanying Figure 1As shown, the heat exchanger 1 and the lithium bromide heat pump 2 are arranged in sequence along the flue gas conveying direction; the heat exchanger 1 has at least gas passages and liquid passages which are independent and exchange heat; the gas passages are respectively provided with an inlet pipe and an outlet pipe at two ends; the outlet pipe is connected with the exhaust pipe 3; the weak solution pipe and / or the generator of the lithium bromide heat pump 2 are heated by heat exchange with the exhaust pipe 3.

[0028] It is worth mentioning that the heat exchanger 1 can be a commonly used industrial heat exchanger such as a shell-and-tube heat exchanger, a plate heat exchanger, a fin heat exchanger, etc.; considering that the flue gas contains many impurities, a shell-and-tube heat exchanger is preferred, and a shell-and-tube heat exchanger using water as the heat exchange medium and fluoroplastic as the heat exchange tube material is further preferred. In the fluoroplastic heat exchanger, the water flows in the heat exchange tube, i.e., the liquid passage; the high-temperature gas flows in the shell and outside the heat exchange tube, i.e., the gas passage. The high-temperature gas and the flowing water exchange heat in the heat exchanger, the flowing water absorbs heat, and the high-temperature gas is discharged from the outlet pipe after releasing heat. The temperature of the high-temperature gas discharged from the outlet pipe of the heat exchanger 1 can generally reach below 85°C.

[0029] It is worth mentioning that the lithium bromide heat pump 2 mainly includes an evaporator, a condenser, an absorber, and a generator, and various pipelines connecting the components; the weak solution pipeline refers to a pipeline for conveying low-concentration lithium bromide aqueous solution from the absorber to the generator, and the lithium bromide aqueous solution in the pipeline has a low temperature; by arranging the exhaust pipe 3 of the flue gas discharged from the heat exchanger 1 downstream of the weak solution pipeline or at the generator, the temperature of the low-concentration lithium bromide aqueous solution flowing into the generator can be increased, the separation of lithium bromide and water can be promoted, and the heat source for the lithium bromide heat pump 2 can be provided. In this process, since the flue gas with residual heat is in the exhaust pipe 3 and does not directly contact any component in the lithium bromide heat pump 2, the service life of the lithium bromide heat pump 2 is not affected. Further, in order to ensure the rapid separation of lithium bromide and water, the pressure in the generator can be selected to be low or even vacuum; at the same time, in order to improve the heat exchange efficiency of the exhaust pipe 3, the pipe length or diameter of the exhaust pipe 3 can be increased, etc. The above methods are conventional choices for those skilled in the art, and therefore the present embodiment will not be described in detail.

[0030] As some preferred embodiments, the multi-stage utilization system further comprises a raw water treatment tank 4 connected to both ends of the liquid passage through a liquid outlet pipe 41 and a liquid return pipe 42. The cooling water pipe of the lithium bromide heat pump 2 is used to control the temperature of the liquid in the raw water treatment tank 4 by directly communicating with the raw water treatment tank 4 / liquid return pipe 42 or indirectly exchanging heat with the liquid return pipe 42. The raw water treatment tank 4 inputs low-temperature or normal-temperature liquid to the heat exchanger 1 through the liquid outlet pipe 41 to absorb heat, and recovers the liquid discharged from the heat exchanger 1 through the liquid return pipe 42. Therefore, how to keep the temperature of the water body in the raw water treatment tank at normal temperature or low temperature after the recovered water is input through the liquid return pipe 42 is the key. In this embodiment, the liquid return pipe 42 is arranged through the cooling water pipe of the lithium bromide heat pump 2, and the cooling water pipe is used to cool the water body in the liquid return pipe 42, which can further improve the recycling of resources and the efficiency of waste heat utilization. It can be understood that the cooling water pipe refers to the circulating pipe at the evaporator, which is used for heat exchange with the outside area of the heat pump. The temperature of the cooling water pipe is generally not more than 7℃, and the cooling effect of the liquid return pipe 42 is obvious.

[0031] As some preferred embodiments, the liquid return pipe 42 is at least formed with a parallel internal loop 421 and an external loop 422, the internal loop 421 is used to exchange heat with the cooling water pipe of the lithium bromide heat pump 2, and a valve is arranged on the internal loop 421. The advantage of such arrangement is that when the cooling water pipe of the lithium bromide heat pump 2 preferentially cools other working areas, the cooling of the internal loop 421 by the cooling water pipe can be closed by closing the valve at the internal loop 421, and the warmed water is recovered to the raw water treatment tank 4 through the external loop 422.

[0032] It can be understood that the so-called other working areas can be water-using mechanisms or other similar mechanisms in the plant area, which generally include a heating part 6 and a cooling part 7. The lithium bromide heat pump 2 is directly / indirectly connected to the heating part 6 to provide heat source to the heating part 6, and the cooling water pipe of the lithium bromide heat pump 2 is directly / indirectly connected to the cooling part 7 to provide cold source to the cooling part 7. It is worth noting that a pump body can be arranged on the passage of the lithium bromide heat pump 2 connected to the heating part 6 and the cooling part 7 to provide conveying power, or a valve can be arranged to control the work of the passage. The pump body and the valve are common structures for those skilled in the art, and therefore the present embodiment will not be described in detail.

[0033] As some preferred embodiments, the liquid return pipe 42 of the raw water treatment tank 4 is directly / indirectly connected to the heating part 6 to provide heat source to the heating part 6. Such arrangement further utilizes the heat of the liquid return pipe 42, and can also cool the temperature of the liquid return pipe 42, improving the utilization efficiency.

[0034] As some preferred embodiments, the multi-stage utilization system further comprises a cooling tower 5 for providing a cold source to the lithium bromide heat pump 2. It is worth mentioning that the cooling tower 5 is mainly used for cooling the condenser and the absorber, improving the efficiency of the lithium bromide heat pump 2. Further, the cooling tower 5 is also used to provide a cold source to the raw water treatment tank 4 or the external loop 422 or the cooling supply part 7; such arrangement improves the utilization efficiency of the cooling tower 5 and helps to improve the working efficiency of the whole system.

[0035] As some preferred embodiments, as shown in the accompanying drawings, Figure 2 As some preferred embodiments, the multi-stage utilization system further comprises a denitration device 8 upstream of the heat exchanger 1, and the outlet of the denitration device is connected with the inlet pipe. The denitration device is mainly used for removing nitrogen oxides in the high-temperature flue gas, avoiding the ammonium salt from being accumulated on the internal structure of the heat exchanger 1 to form a crystalline structure that is difficult to remove, affecting the heat exchange efficiency and the service life of the heat exchanger 1. The denitration device uses ammonia as a reducing agent, and a catalyst bed is arranged inside the device. The nitrogen oxides are reduced with the ammonia to form nitrogen and water, etc., reducing the content of ammonium salt in the flue gas. In addition, the heat of the high-temperature flue gas can also improve the catalytic efficiency of the catalyst and improve the working efficiency of the denitration device.

[0036] It can be understood that the multi-stage utilization system can also be provided with a dust removal device and a desulfurization device downstream of the lithium bromide heat pump 2 to meet the emission standards of the flue gas. The dust removal device and the desulfurization device are well known to those skilled in the art, and therefore this embodiment will not be described in detail.

[0037] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art of the present application can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without deviating from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A multi-stage utilization system of kiln flue gas waste heat, characterized in that: The heat exchanger (1), the lithium bromide heat pump (2) are arranged in sequence along the flue gas conveying direction. The heat exchanger (1) has gas passage and liquid passage which are independent and exchange heat, the gas passage has inlet pipe and outlet pipe at two ends, the outlet pipe is connected with exhaust pipe (3). The weak solution pipe and / or generator of the lithium bromide heat pump (2) heat the fluid in the weak solution pipe and / or generator by heat exchange with the exhaust pipe (3).

2. The multi-stage utilization system of kiln flue gas waste heat according to claim 1, characterized in that: The raw water treatment tank (4) is connected with the two ends of the liquid passage through outlet pipe (41) and return pipe (42).

3. The multi-stage utilization system of kiln flue gas waste heat according to claim 2, characterized in that: The cooling water pipe of the lithium bromide heat pump (2) is used to control the liquid temperature in the raw water treatment tank (4) by directly communicating with the raw water treatment tank (4) / return pipe (42) or indirectly exchanging heat with the return pipe (42).

4. The multi-stage utilization system of kiln flue gas waste heat according to claim 3, characterized in that: The return pipe (42) has internal loop (421) and external loop (422) in parallel, the internal loop (421) is used to exchange heat with the cooling water pipe of the lithium bromide heat pump (2) and has valve.

5. The multi-stage utilization system of kiln flue gas waste heat according to claim 2, characterized in that: The lithium bromide heat pump (2) is directly / indirectly connected with heat supply part (6) to provide heat source for the heat supply part (6).

6. The multi-stage utilization system of kiln flue gas waste heat according to claim 5, characterized in that: The return pipe (42) of the raw water treatment tank (4) is directly / indirectly connected with the heat supply part (6) to provide heat source for the heat supply part (6).

7. The multi-stage utilization system of kiln flue gas waste heat according to claim 4, characterized in that: The cooling water pipe of the lithium bromide heat pump (2) is directly / indirectly connected with cooling part (7) to provide cold source for the cooling part (7).

8. The multi-stage utilization system of kiln flue gas waste heat according to claim 7, characterized in that: The cooling tower (5) is used to provide cold source for the lithium bromide heat pump (2).

9. The multi-stage utilization system of kiln flue gas waste heat according to claim 8, characterized in that: The cooling tower (5) is also used to provide cold source for the raw water treatment tank (4) or the external loop (422) or the cooling part (7).

10. The multi-stage utilization system of kiln flue gas waste heat according to claim 1, characterized in that: The denitration device (8) is arranged upstream of the heat exchanger (1), the outlet of the denitration device is connected with the inlet pipe.

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