Flue gas waste heat recovery system

Abstract

The utility model discloses a flue gas waste heat recovery system which comprises a vaporization flue and a waste heat boiler. The vaporization flue comprises a furnace mouth section, a middle section and a tail section which are arranged in sequence; an inlet of the furnace mouth section is vertically downward and is positioned right above the AOD furnace; an outlet of the furnace mouth section is inclined upwards; an inlet of the middle section inclines downwards and is connected with an outlet of the furnace mouth section through an expansion compensator; an outlet of the middle section is horizontal and is communicated with an inlet of the tail section, the middle part of the tail section is inclined, and an outlet of the tail section is horizontal and is connected with an inlet of the waste heat boiler; and an outlet of the waste heat boiler is communicated with an inlet of the secondary dust removal pipeline through a flue gas outlet pipeline. The system has the advantages that the vaporization flue is connected with the waste heat boiler, smoke waste heat can be greatly recycled, energy is saved, emission is reduced, and economic benefits and social benefits of a steel mill are greatly improved; meanwhile, according to the limitation of the workshop space, a vertical combination mode and a horizontal combination mode are provided, and the configuration requirements of different steel mills can be met.

Description

Technical Field

[0001] The utility model relates to a flue gas waste heat recovery technology, in particular to a flue gas waste heat recovery system. Background Art

[0002] Energy conservation and waste heat utilization are hot topics of common concern around the world and are a vital task in the process of my country's economic development. The AOD furnace (argon oxygen decarburization furnace, argon oxygen refining equipment) uses a complete combustion method, and the high-temperature flue gas produced after combustion carries a large amount of high-grade sensible heat. In order to make the flue gas meet the emission standards, the existing flue gas needs to be cooled and dusted.

[0003] At present, the flue gas cooling and dust removal process of some steel plants is to first use a water-cooled flue to cool the high-temperature flue gas, and then set up a circulating water cooling system to directly reduce the flue gas temperature to about 200°C before sending it to the bag filter. It is feasible to use this method to cool the high-temperature flue gas to meet the emission standards, but it does not fully utilize the waste heat in the high-temperature flue gas, and also consumes a lot of water resources and electricity.

[0004] Therefore, it is necessary to improve the prior art. Summary of the invention

[0005] The utility model aims to provide a flue gas waste heat recovery system to address the deficiencies of the prior art, aiming to cool the flue gas and recover and utilize the waste heat in the flue gas at the same time.

[0006] The technical solution adopted by the utility model is: a flue gas waste heat recovery system, comprising a vaporization flue and a waste heat boiler; the vaporization flue comprises a furnace mouth section, a middle section and a tail section arranged in sequence; the inlet of the furnace mouth section is vertically downward and is located directly above the AOD furnace; the outlet of the furnace mouth section is inclined upward; the inlet of the middle section is inclined downward and is connected to the outlet of the furnace mouth section through an expansion compensator; the outlet of the middle section is horizontal and is connected to the inlet of the tail section, the middle part of the tail section is inclined, and the outlet of the tail section is horizontal and is connected to the inlet of the waste heat boiler; the outlet of the waste heat boiler is connected to the inlet of the secondary dust removal pipeline through the flue gas outlet pipeline.

[0007] According to the above scheme, each flue section of the vaporization flue is respectively provided with a heat exchange tube for exchanging heat with the flue gas.

[0008] According to the above scheme, the furnace mouth section, the middle section and the tail section are respectively provided with a manhole and a hand hole.

[0009] According to the above scheme, the waste heat boiler is a horizontal double-pressure waste heat boiler, including a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section of the vaporization flue through an expansion compensator; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator and a low-temperature evaporator are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator and the low-temperature evaporator are connected through a transition section flue; the medium-temperature evaporator is connected to the steam drum, and the steam drum is connected to the user through a steam pipe.

[0010] According to the above scheme, the middle part of the tail section is inclined upward, and the outlet of the tail section is higher than the inlet of the tail section; the outlet of the tail section is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler through an expansion compensator.

[0011] According to the above scheme, an ash hopper and an ash discharge valve are arranged at the inlet end of the tail section.

[0012] According to the above scheme, a maintenance manhole is set on the transition section flue.

[0013] According to the above scheme, the waste heat boiler is a vertical double-pressure waste heat boiler, including a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section of the vaporization flue through an expansion compensator; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator and a low-temperature evaporator are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator is connected to the steam drum, and the steam drum is connected to the user through a steam pipe.

[0014] According to the above scheme, the boiler furnace includes a first cavity and a second cavity, and the bottom of the first cavity is connected to the bottom of the second cavity by a horizontally connected flue; a plurality of medium-temperature evaporators are arranged from top to bottom in the first cavity connected to the flue inlet, and at least one medium-temperature evaporator and a low-temperature evaporator are arranged from bottom to top in the second cavity connected to the flue inlet; the flue gas enters the boiler furnace through the flue gas inlet, and after heat exchange with each medium-pressure heat exchanger in the first cavity, it flows into the second cavity through the horizontally connected flue at the bottom of the first cavity, and after heat exchange with each medium-temperature evaporator and low-temperature evaporator in turn, it flows out of the furnace through the flue gas outlet.

[0015] According to the above scheme, the middle part of the tail section is inclined downward, and the outlet of the tail section is lower than the inlet of the tail section; the outlet of the tail section is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler through an expansion compensator.

[0016] The beneficial effects of the utility model are as follows: the vaporization flue in the utility model is connected with the waste heat boiler, which can greatly recover the waste heat of the flue gas, save energy and reduce emissions, and greatly improve the economic and social benefits of the steel plant; at the same time, according to the limitations of the plant space, vertical and horizontal waste heat boilers are provided, and the specific structure of the flue is designed according to the structural form and installation position of the waste heat boiler, which can meet the configuration requirements of different steel plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of Example 1.

[0018] Figure 2 This is a schematic diagram of the structure of Example 2.

[0019] Among them: 1. furnace mouth section; 2. middle section; 3. tail section; 4. expansion compensator; 5. waste heat boiler; 6. steam drum; 7. feeding chute sleeve; 8. oxygen gun hole sleeve; 9. flue gas outlet pipe; 10. ash hopper; 11. medium temperature evaporator 11; 12. low temperature evaporator. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] A flue gas waste heat recovery system, specifically a flue gas waste heat recovery system coupling a vaporization flue and a waste heat boiler 5, comprising a vaporization flue and a waste heat boiler 5; the vaporization flue comprises a furnace mouth section 1, a middle section 2 and a tail section 3 arranged in sequence; the inlet of the furnace mouth section 1 is vertically downward and is located directly above the AOD furnace, and a charging chute sleeve 7 is provided at the inlet of the furnace mouth section 1; the outlet of the furnace mouth section 1 is inclined upward and is provided with an oxygen gun hole sleeve 8; the inlet of the middle section 2 is inclined downward and is connected to the outlet of the furnace mouth section 1 through an expansion compensator 4; the outlet of the middle section 2 is horizontal and is connected to the inlet of the tail section 3, the middle part of the tail section 3 is inclined, and the outlet of the tail section 3 is horizontal and is connected to the inlet of the waste heat boiler 5; the outlet of the waste heat boiler 5 is connected to the inlet of the secondary dust removal pipe through a flue gas outlet pipe 9, and the secondary dust removal flue is connected to a subsequent dust removal process system (such as a bag filter).

[0022] In the utility model, each flue section of the vaporization flue is respectively provided with a heat exchange tube for exchanging heat with the flue gas. Cooling water flows in the heat exchange tube. The cooling water is converted into a steam-water mixture after heat exchange with the flue gas. The steam therein can be collected and utilized. This is the prior art and will not be described in detail here.

[0023] In the present invention, the configuration and connection of the secondary dust removal flue and the subsequent dust removal process system are mature technologies in the industry and will not be described in detail here.

[0024] In the utility model, the furnace mouth section 1 is located directly above the AOD furnace, and the flue gas in the AOD furnace enters the furnace mouth section 1, and the furnace mouth section 1 changes the direction of the flue gas from the vertical direction to the oblique upward direction; the middle section 2 is between the furnace mouth section 1 and the tail section 3, and changes the direction of the flue gas from the oblique upward direction to the horizontal direction; the tail section 3 is arranged after the middle section 2, and is used to connect the horizontal double-pressure waste heat boiler 5, so that the direction of the flue gas is first changed from the horizontal direction to the oblique direction and then to the horizontal direction.

[0025] In the present invention, the expansion compensator 4 is made of non-metallic material and is used to absorb the axial displacement caused by the thermal expansion of the vaporization cooling flue. The expansion compensator 4 is a mature structure in the industry and will not be described here.

[0026] In the present invention, the oxygen gun hole sleeve 8 is used to blow oxygen for the oxygen gun; the feeding chute sleeve 7 is used to add materials such as ferroalloy and limestone. In the present invention, the structures and functions of the oxygen gun hole sleeve 8 and the feeding chute sleeve 7 are all existing technologies in the industry, and will not be described in detail here.

[0027] Preferably, the furnace mouth section 1, the middle section 2 and the tail section 3 are respectively provided with a manhole and a hand hole to facilitate maintenance and cleaning.

[0028] In the present invention, the vaporization flue is a radiation flue, and the flue gas is cooled to 900-1000° C. after passing through the vaporization flue. Below 850° C., the radiation heat exchange effect will be significantly reduced, and it is not suitable to use a radiation flue gas waste heat recovery flue at this time, so a waste heat boiler 5 is connected to the tail of the vaporization flue for further cooling the flue.

[0029] Example 1

[0030] like Figure 1 As shown, the waste heat boiler 5 is a horizontal double-pressure waste heat boiler 5, which is generally arranged on the roof of the steel plant. The flue gas inlet of the horizontal double-pressure waste heat boiler 5 is relatively high (higher than the tail section 3). The horizontal double-pressure waste heat boiler 5 includes a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section 3 of the vaporization flue through an expansion compensator 4; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator 11 and a low-temperature evaporator 12 are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator 11 and the low-temperature evaporator 12 are connected through a transition section flue; the medium-temperature evaporator 11 is connected to the steam drum 6, and the steam drum 6 is connected to the user through a steam pipeline for heating or saturated steam power generation.

[0031] In this embodiment, after the flue gas coming out of the vaporization flue enters the horizontal double-pressure waste heat boiler 5, it flows through the medium-temperature evaporator 11 and the low-temperature evaporator 12 in sequence and then exits the horizontal double-pressure waste heat boiler 5; the steam drum 6 is used to recover the steam generated after heat exchange in the medium-temperature evaporator 11, and transport the steam to the user for use.

[0032] In this embodiment, since the flue gas inlet of the horizontal waste heat boiler 5 is higher than the tail section 3, the middle of the tail section 3 is inclined upward, and the outlet of the tail section 3 is higher than the inlet of the tail section 3. Figure 1 As shown; the outlet of the tail section 3 is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler 5 through the expansion compensator 4. The inlet end of the tail section 3 is a low point, and an ash hopper 10 and an ash discharge valve are arranged at the inlet end of the tail section 3. The accumulated ash generated by the tail section 3 falls into the ash hopper 10 and is sent away through the subsequent ash conveying system.

[0033] In this embodiment, the horizontal double-pressure waste heat boiler 5 is a double-pressure vertical boiler, which uses a light tube as a heat exchange surface. The evaporator absorbs the sensible heat of the flue gas to reduce the flue gas temperature and generate saturated steam. The steam drum 6 can be arranged on the roof of the factory building, which can save the floor space of the factory building. A maintenance manhole and a dust cleaning device are set on the transition section flue. The horizontal double-pressure waste heat boiler 5 adopts a shock wave soot blowing system. The working principle is to mix air and combustible gas in a certain proportion, and after high-energy ignition, a shock wave of controllable intensity is formed in the shock wave generator. The impact kinetic energy sweeps the heating surface while accompanied by high-intensity sound wave oscillation and thermal cleaning, so as to achieve the purpose of blowing away the accumulated dust to ensure the cleanliness of the heating surface, improve the heat transfer efficiency, and restore the boiler output; the dust falls into the ash hopper 10 of the boiler, and is sent away through the subsequent ash conveying system. The outlet of the ash hopper 10 is provided with an ash discharge valve. In this embodiment, the shock wave soot blowing system is a mature technology in the industry and will not be described here.

[0034] The working principle of this embodiment is as follows: the primary flue gas in the AOD furnace enters the furnace mouth section 1 of the vaporization flue, and after the direction of the flue gas changes from the vertical direction to the oblique upward direction, it enters the middle section 2 through the furnace mouth section 1, and the direction of the flue gas in the middle section 2 changes from the oblique upward direction to the horizontal direction, and enters the tail section 3. At this time, the direction of the flue gas first changes from the horizontal direction to the oblique upward direction and then to the horizontal direction; the flue gas exchanges heat with the cooling water in the heat exchange tube in the vaporization flue, and partially vaporizes to form a steam-water mixture, and the steam is collected and utilized to achieve To achieve the purpose of flue gas waste heat recovery; the flue gas is heat-exchanged in the vaporization flue furnace section 1, the middle section 2 and the tail section 3 in turn, and the temperature is reduced to 900-1000°C, and then enters the horizontal double-pressure waste heat boiler 5 in turn, and exchanges heat in the medium-temperature evaporator 11 and the low-temperature evaporator 12 in turn. The steam generated after the heat exchange is collected by the steam drum 6 and sent to the user for use; the flue gas after heat exchange leaves the horizontal double-pressure waste heat boiler 5, at which time the flue gas temperature drops to about 200°C, and then is mixed into the secondary flue gas pipeline through the flue gas outlet flue.

[0035] Example 2

[0036] like Figure 2As shown, the waste heat boiler 5 is a vertical double-pressure waste heat boiler 5, which can be arranged inside the steel plant building, and the flue gas inlet of the vertical double-pressure waste heat boiler 5 is relatively low. The vertical double-pressure waste heat boiler 5 includes a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section 3 of the vaporization flue through an expansion compensator 4; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator 11 and a low-temperature evaporator 12 are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator 11 is connected to the steam drum 6, and the steam drum 6 is connected to the user through a steam pipeline for heating or saturated steam power generation.

[0037] In this embodiment, the boiler furnace includes a first cavity and a second cavity, and the bottom of the first cavity is connected to the bottom of the second cavity by a horizontally connected flue; a plurality of medium-temperature evaporators 11 are arranged from top to bottom in the first cavity connected to the flue inlet, and at least one medium-temperature evaporator 11 and a low-temperature evaporator 12 are arranged from bottom to top in the second cavity connected to the flue inlet; the flue gas enters the boiler furnace through the flue gas inlet, and after heat exchange with each medium-pressure heat exchanger in the first cavity, it flows into the second cavity through the horizontally connected flue at the bottom of the first cavity, and after heat exchange with each medium-temperature evaporator 11 and the low-temperature evaporator 12 in turn, it flows out of the furnace through the flue gas outlet.

[0038] In this embodiment, the vertical dual-pressure waste heat boiler 5 is arranged in the steel plant building. The flue gas inlet of the waste heat boiler 5 is lower than the tail section 3. Therefore, the middle part of the tail section 3 is inclined downward, and the outlet of the tail section 3 is lower than the inlet of the tail section 3. Figure 2 The outlet of the tail section 3 is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler 5 through the expansion compensator 4.

[0039] In this embodiment, the vertical double-pressure waste heat boiler 5 uses a light tube as a heat exchange surface. The evaporator absorbs the sensible heat of the flue gas to reduce the flue gas temperature and generate saturated steam; an inspection manhole and a dust cleaning device are set on the transition section flue between the first cavity and the second evaporator. The vertical double-pressure waste heat boiler 5 adopts a shock wave soot blowing system. The working principle is to mix air and combustible gas in a certain proportion, and after high-energy ignition, a shock wave of controllable intensity is formed in the shock wave generator. The impact kinetic energy sweeps the heating surface while accompanied by high-intensity sound wave oscillation and thermal cleaning, so as to achieve the purpose of blowing away the accumulated dust to ensure the cleanliness of the heating surface, improve the heat transfer efficiency, and restore the boiler output. In this embodiment, a plurality of ash hoppers 10 are respectively provided at the bottom of the first cavity and the second cavity, and the dust falls into the ash hopper 10 provided by the boiler, and an ash discharge valve is provided at the outlet of the ash hopper 10.

[0040] The working principle of this embodiment is as follows: the primary flue gas in the AOD furnace enters the furnace mouth section 1 of the vaporization flue, and after the direction of the flue gas changes from the vertical direction to the oblique upward direction, it enters the middle section 2 through the furnace mouth section 1, and the direction of the flue gas in the middle section 2 changes from the oblique upward direction to the horizontal direction, and enters the tail section 3. At this time, the direction of the flue gas changes from the horizontal direction to the oblique downward direction and then to the horizontal direction; the flue gas exchanges heat with the cooling water in the heat exchange tube in the vaporization flue, and partially vaporizes to form a steam-water mixture, and the steam is collected and utilized to achieve the purpose of flue gas waste heat recovery; the flue gas is sequentially discharged in the furnace mouth section 1, the middle section 2 and the tail section of the vaporization flue. After heat exchange in section 3, the temperature drops to 900-1000°C, and then enters the vertical double-pressure waste heat boiler 5 in turn. After heat exchange with each medium-pressure heat exchanger in the first cavity, it flows into the second cavity through the horizontal connecting flue at the bottom of the first cavity, and exchanges heat through each medium-temperature evaporator 11 and the low-temperature evaporator 12 in turn. The cooling water in the evaporator becomes a steam-water mixture after heat exchange, and the steam is collected by the steam drum 6 and sent to the user for use, so as to achieve the purpose of flue gas waste heat recovery; the flue gas after heat exchange flows out of the boiler furnace through the flue gas outlet, and the flue gas temperature drops to about 200°C at this time, and then enters the secondary flue gas duct through the flue gas outlet flue.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flue gas waste heat recovery system, characterized in that: It includes a vaporization flue and a waste heat boiler; the vaporization flue includes a furnace mouth section, a middle section and a tail section arranged in sequence; the inlet of the furnace mouth section is vertically downward and is located directly above the AOD furnace; the outlet of the furnace mouth section is inclined upward; the inlet of the middle section is inclined downward and is connected to the outlet of the furnace mouth section through an expansion compensator; the outlet of the middle section is horizontal and communicated with the inlet of the tail section, the middle part of the tail section is inclined, the outlet of the tail section is horizontal and connected to the inlet of the waste heat boiler; the outlet of the waste heat boiler is connected to the inlet of the secondary dust removal pipeline through a flue gas outlet pipeline.

2. The flue gas waste heat recovery system according to claim 1, characterized in that: Each flue section of the vaporization flue is respectively provided with a heat exchange tube for exchanging heat with the flue gas.

3. The flue gas waste heat recovery system according to claim 1, characterized in that: The furnace mouth section, the middle section and the tail section are respectively provided with a manhole and a hand hole.

4. The flue gas waste heat recovery system according to claim 1, characterized in that: The waste heat boiler is a horizontal double-pressure waste heat boiler, including a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section of the vaporization flue through an expansion compensator; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator and a low-temperature evaporator are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator and the low-temperature evaporator are connected through a transition section flue; the medium-temperature evaporator is connected to a steam drum, and the steam drum is connected to a user through a steam pipe.

5. The flue gas waste heat recovery system according to claim 4, characterized in that: The middle part of the tail section is inclined upward, and the outlet of the tail section is higher than the inlet of the tail section; the outlet of the tail section is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler through an expansion compensator.

6. The flue gas waste heat recovery system according to claim 5, characterized in that: An ash hopper and an ash discharge valve are provided at the inlet end of the tail section.

7. The flue gas waste heat recovery system according to claim 5, characterized in that: A maintenance manhole is provided on the transition section flue.

8. The flue gas waste heat recovery system according to claim 1, characterized in that: The waste heat boiler is a vertical double-pressure waste heat boiler, including a boiler furnace, one end of which is provided with a flue gas inlet, which is connected to the tail section of the vaporization flue through an expansion compensator; the other end of the boiler furnace is provided with a flue gas outlet; a medium-temperature evaporator and a low-temperature evaporator are sequentially arranged in the boiler furnace along the flue gas flow direction; the medium-temperature evaporator is connected to a steam drum, and the steam drum is connected to a user through a steam pipe.

9. The flue gas waste heat recovery system according to claim 8, characterized in that: The boiler furnace comprises a first cavity and a second cavity, the bottom of the first cavity and the bottom of the second cavity are connected with a horizontally connected flue; a plurality of medium-temperature evaporators are arranged from top to bottom in the first cavity connected with the flue inlet, and at least one medium-temperature evaporator and a low-temperature evaporator are arranged from bottom to top in the second cavity connected with the flue inlet; The flue gas enters the boiler furnace through the flue gas inlet, exchanges heat with each medium-pressure heat exchanger in the first cavity, flows into the second cavity through the horizontal connecting flue at the bottom of the first cavity, exchanges heat with each medium-temperature evaporator and low-temperature evaporator in turn, and then flows out of the furnace through the flue gas outlet.

10. The flue gas waste heat recovery system according to claim 8, characterized in that: The middle part of the tail section is inclined downward, and the outlet of the tail section is lower than the inlet of the tail section; the outlet of the tail section is connected to the flue gas inlet of the horizontal double-pressure waste heat boiler through an expansion compensator.

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