CN218627807U

CN218627807U - Kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln

Info

Publication number: CN218627807U
Application number: CN202223079821.8U
Authority: CN
Inventors: 方明; 张冬冬; 王朝雄; 刘亚雷
Original assignee: Nanjing Kesen Kenen Environment & Energy Co ltd
Current assignee: Nanjing Kesen Kenen Environment & Energy Co ltd
Priority date: 2022-11-21
Filing date: 2022-11-21
Publication date: 2023-03-14
Anticipated expiration: 2032-11-21

Abstract

The utility model provides a kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln, the device adopts vertical structure, and top-down includes device entry, exhaust-heat boiler in proper order, removes ash structure, SCR denitration reactor and device export in advance. The waste heat boiler comprises an evaporator, a superheater and a boiler barrel. The pre-ash-removing structure comprises a flue gas guide plate, an ash catcher and an ash flying bin. The SCR denitration reactor comprises a catalyst module layer and a catalystThe module layer is formed by combining catalyst modules, the catalyst modules are in a porous penetrating structure, and smoke passes through the pores of the catalyst modules to realize NO _x And (4) removing. The utility model has compact structure, small occupied area and small heat loss of the system after practical application; realize multistage deashing through mechanical rapping device, ash removal structure, harrow formula soot blower in advance, can effectively reduce the wearing and tearing of flying dust granule to denitration catalyst to reduce SCR denitration's jam risk.

Description

Kiln tail waste heat boiler and SCR denitration integrated device suitable for cement kiln

Technical Field

The utility model relates to a waste heat utilization and clarification plant of cement plant kiln tail flue gas especially relate to a kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln.

Background

China is a big cement producing country, and as far as 2020, 1712 new dry normal lines exist in China, the annual output reaches 23.16 hundred million tons, and the cement yield accounts for more than half of the world cement yield. As one of the main pollutant emissions in the atmosphere, NOx is an important precursor for the generation of photochemical pollution and is also a significant cause of regional fine particle pollution and haze. The emission of NOx in the cement industry accounts for about 10 percent of the total emission in China, and the NOx is discharged after thermal power generation and automobile exhaust emission, and belongs to the key pollution control industry. At present, the cement enterprises in China implement ultralow emission, and the mainstream process for denitration adopts an SCR denitration process, and a catalyst is used for catalyzing ammonia and nitric oxide to react to generate nitrogen.

The cement kiln tail flue gas has the characteristic of large dust content, and the dust concentration in the flue gas at the air outlet of the preheater can reach 100g/Nm to the maximum ³ The above. On one hand, the high-dust flue gas directly scours the surface of the catalyst, so that the service life of the catalyst at the top of the denitration reactor is shortened; on the other hand, a large amount of fly ash is attached to the upper surface of the catalyst layer, so that the ash removal difficulty of the rake type soot blower is increased, and holes of the catalyst module are easy to block. With the continuous promotion of the policy of energy conservation and emission reduction, waste heat power generation of cement plants becomes a necessary facility in the plants.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: problem to prior art existence, the utility model provides a kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln through the rational design device structure, fuses waste heat power generation and SCR denitration reactor degree of depth, implements energy saving and emission reduction and ultralow emission to the cement enterprise and has apparent impetus.

The technical scheme is as follows: the utility model relates to a kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln, the integrated device is a vertical structure, and comprises a device inlet, an exhaust-heat boiler, a pre-ash-removing structure, an SCR denitration reactor and a device outlet from top to bottom in sequence;

the waste heat boiler comprises an evaporator, a superheater and a boiler barrel; the boiler barrel is respectively communicated with the evaporator and the superheater; the outer vertical surface of the evaporator and/or the superheater is provided with a mechanical rapping device, and fly ash attached to the heat exchange tubes in the evaporator and/or the superheater is removed through continuous rapping;

preferably, the evaporator and the superheater are both of box body structures, and the box body spaces of the evaporator and the superheater are communicated up and down and are used for circulating flue gas; the boiler comprises an evaporator and is characterized in that a first internal heat exchange tube is arranged in a box body of the evaporator, a second internal heat exchange tube is arranged in a box body of the superheater, and a boiler barrel is communicated with the first internal heat exchange tube and the second internal heat exchange tube respectively. Preferably, the first inner heat exchange tube and/or the second inner heat exchange tube are horizontally suspended in the box body. And the contact surfaces of the evaporator and the superheater are connected and sealed by adopting a welding process.

The pre-ash-removing structure comprises a flue gas guide plate, an ash catcher and a fly ash bin, wherein the flue gas guide plate and the ash catcher are oppositely arranged at the outlet end of the waste heat boiler; the opening of the ash catcher is upward and is arranged in a staggered way with the flue gas guide plate; the pipeline of the ash catcher is communicated with the fly ash bin;

preferably, the flue gas guide plate is an inverted V-shaped angle steel structure. The ash catching port of the ash catcher is of an inverted quadrangular frustum pyramid structure, the tail end of the ash catching port is connected with vertical pipelines, a plurality of vertical pipelines are connected with a first pipeline, and the first pipeline is obliquely arranged and is used for collecting fly ash in the ash catchers to one side of the device; the first pipeline is connected with the fly ash bin through a second pipeline. Preferably, the device comprises a spiral ash conveying device, and the spiral ash conveying device is in transmission connection with the fly ash bin.

The SCR denitration reactor comprises a catalyst module layer, wherein the catalyst module layer is formed by combining a plurality of catalyst modules, the catalyst modules are of a porous penetrating structure, and flue gas is catalyzed by the catalyst modulesThe reagent module passes through the hole to realize NO _x Removing;

preferably, the side surface of the SCR denitration reactor is provided with a suspension device for meeting the hoisting requirement of the failure replacement of the catalyst module.

Further preferably, the device comprises a rake type soot blower, wherein the blowing point of the rake type soot blower is arranged on the upper surface of the catalyst module layer, and the soot bin is arranged below the catalyst module layer.

High-temperature flue gas from the tail of the cement kiln enters an inlet of the device, and is subjected to heat convection with a waste heat boiler to generate superheated steam; the cooled flue gas enters a pre-ash-removing structure, is subjected to flow guide segregation under the action of a flue gas guide plate, fly ash in the flue gas enters an ash catcher under the action of air pressure and inertia force, is conveyed to a fly ash bin through a pipeline, the flue gas from which part of fly ash is removed enters an SCR (selective catalytic reduction) denitration reactor, and NO (nitric oxide) is removed under the action of the SCR denitration reactor _x And the treated smoke is discharged from the outlet of the device.

Has the advantages that:

compared with the prior art, the utility model discloses has following progress:

(1) The waste heat boiler and the SCR denitration reactor are integrally designed and are arranged in a vertical structure, so that the appearance structure of the whole device is more compact, the system resistance is reduced, the heat dissipation capacity of the device is reduced, and the occupied area of a plant area is greatly reduced; the system has small heat loss after practical application, and can effectively ensure the integrated functions of waste heat recovery and denitration at the tail of the cement kiln.

(2) The ash content in the cement kiln tail flue gas is large, and the blockage risk is easy to occur in SCR denitration; meanwhile, a pre-ash removal structure is arranged between the waste heat boiler and the SCR denitration reactor, and partial fly ash is removed by the action of inertia force; in addition, in the denitration process, the dust on the surface of the catalyst is further removed through a rake type soot blower; through the multistage deashing mechanism of the aforesaid, the utility model discloses can effectively reduce flying dust granule to the wearing and tearing of denitration catalyst, reduce the jam risk of SCR denitration.

Drawings

FIG. 1 is a schematic structural view of a kiln tail waste heat boiler and an SCR denitration integrated device which are suitable for a cement kiln of the utility model;

in the figure: 1-device inlet; 2-an evaporator; 3-a superheater; 4-a platform staircase; 5-a boiler barrel; 6-flue gas guide plate; 7-a cross beam; 8-an ash catcher; 9-a first conduit; 10-a second pipeline; 11-a catalyst module layer; 12-rake sootblowers; 13-a suspension device; 14-device outlet; 15-fly ash bin; 16-a spiral ash conveying device; 17-upright post; i, a waste heat boiler; II, pre-ash removal structure; III-SCR denitration reactor.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

As shown in fig. 1, the kiln tail exhaust-heat boiler and SCR denitration integrated device suitable for cement kiln of this embodiment adopts vertical structure, is wholly supported by stand 17, and top-down includes device entry 1, exhaust-heat boiler i, ash removal structure ii, SCR denitration reactor iii and device export 14 in proper order.

The waste heat boiler I comprises an evaporator 2, a superheater 3 and a boiler barrel 5, and the boiler barrel 5 is respectively communicated with pipelines of the evaporator 2 and the superheater 3. Preferably, the evaporator 2 and the superheater 3 both adopt a box type structure, and heat exchange tubes are arranged in the boxes of the evaporator 2 and the superheater 3; the space of the upper box body and the space of the lower box body are communicated, and a gap is reserved between the heat exchange tubes and used for circulating flue gas. Specifically, a first internal heat exchange tube is arranged in the box body of the evaporator 2, a second internal heat exchange tube is arranged in the box body of the superheater 3, and the boiler barrel 5 is communicated with the first internal heat exchange tube and the second internal heat exchange tube respectively. Mechanical rapping devices are arranged on the outer vertical surfaces of the box body structures of the evaporator 2 and the superheater 3 so as to realize the continuous rapping dust-cleaning function of each heat exchange tube in the box body. Further preferably, the internal heat exchange tubes of the evaporator 2 and the superheater 3 are both horizontally arranged and suspended in the box body, for example, a fixed part such as a beam is welded on the box body, and the heat exchange tubes are suspended on the beam; the suspension arrangement aims to increase the freedom of movement of the heat exchange tube and reduce the thermal stress generated by thermal expansion and the cyclic stress caused by mechanical rapping. Furthermore, the contact surfaces between the box bodies are connected by adopting a welding process so as to ensure the sealing property.

The pre-ash-removing structure II comprises a flue gas guide plate 6, an ash catcher 8 and a fly ash bin 15. Specifically, two layers of cross beams 7 are sequentially arranged at the outlet end of the waste heat boiler I, and a flue gas guide plate 6 and an ash catcher 8 are respectively fixed on the cross beams 7 at two sides; the flue gas guide plate 6 is preferably an inverted V-shaped angle steel structure and is vertically welded with the first layer of cross beams; the ash catching port of the ash catcher 8 is upward, preferably adopts an inverted quadrangular frustum pyramid structure, and is vertically welded with the second layer of cross beams; according to fig. 1, a plurality of flue gas guide plates 6 and a plurality of ash traps 8 are uniformly distributed along the cross beam 7, wherein the ash traps 8 are preferably arranged along the lower space of the gap between the flue gas guide plates 6, so that more fly ash can be collected by the ash trap; the figure shows that the structure is only one group of cross beams 7, and in practical application, the number of the cross beams 7 and the arrangement number of the flue gas guide plate 6 and the ash catcher 8 are reasonably adjusted according to the section size of the device.

Furthermore, the tail end of an ash catching port of the ash catcher 8 is connected with a vertical pipeline, a plurality of vertical pipelines are connected with a first pipeline 9, the first pipeline 9 is obliquely arranged to collect the fly ash to one side of the device, the first pipeline 9 is communicated with a fly ash bin 15 through a second pipeline 10, and the fly ash bin 15 can adopt an ash bucket.

The SCR denitration reactor III comprises a catalyst module layer 11, the catalyst module layer 11 is formed by combining a plurality of catalyst modules, the catalyst modules are of a porous penetrating structure, and flue gas penetrates through holes of the catalyst modules to realize NO _x And (4) removing. Preferably, a suspension device 13 is arranged on the side of the catalyst module layer 11 for the hoisting requirement of the catalyst module failure replacement. Further, configuring a rake type soot blowing device for the SCR denitration reactor IIIThe device 12, the blowing point of the rake type soot blower 12 is arranged on the upper surface of the catalyst module layer 11, the fly ash bin 15 is preferably arranged below the catalyst module layer 11 and is used for collecting fly ash blown and removed by the rake type soot blower 12, and the fly ash bin 15 is in transmission connection with the spiral ash conveying device 16 for facilitating conveying and cleaning of the fly ash.

Furthermore, the device also comprises a plurality of platform escalators 4 which are used for patrol and overhaul when the device is in normal operation.

The working principle of the kiln tail waste heat boiler and the SCR denitration integrated device is as follows:

(1) High-temperature flue gas from the tail of a cement kiln enters an inlet 1 of the device, and is subjected to heat convection with heat exchange tubes in boxes of a waste heat boiler I to generate superheated steam; the flue gas cooled to about 200 ℃ enters a pre-ash removal structure II, part of fly ash is removed, the flue gas enters an SCR denitration reactor III, and NO is removed through the action of the SCR denitration reactor III _x The treated flue gas is removed from the device outlet 14.

(2) Hot water from a kiln head enters a boiler barrel 5 of a kiln tail waste heat boiler I, is mixed with saturated water in the boiler barrel 5 and then respectively enters an evaporator 2 along a descending pipe below the boiler barrel 5, part of steam is generated after the heat is absorbed, a steam-water mixture leaves the evaporator 2 and enters the boiler barrel 5, the saturated water continuously circulates through a steam-water separation device in the boiler barrel 5, and the saturated steam enters a superheater 3 after coming out of the top of the boiler barrel 5 and is further changed into superheated steam after absorbing heat.

(3) The flue gas flows through the pre-dedusting structure II, the flue gas guide plate 6 guides the flue gas at the outlet of the waste heat boiler I to be segregated, the fly ash enters the ash catcher 8 under the action of air pressure and inertia force and enters the fly ash bin 15 through the fly ash pipeline, and the dust content of the pre-dedusted flue gas is greatly reduced.

(4) Flue gas flows through SCR denitration reactor III, and under the effect of the flue gas of premixed ammonia denitration catalyst in multilayer catalyst module layer 11, nitrogen oxide is reacted into harmless nitrogen gas, and rake type soot blower 12 keeps continuous cycle in-process at the denitration and sweeps, clears away the dust on catalyst surface, prevents that catalyst module layer 11 upper surface area ash from blockking up. The catalyst which is out of work for a long time is installed and replaced by the suspension device 13. The deposited ash in the fly ash bin 15 is delivered out by the spiral ash conveying device 16.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.

Claims

1. The integrated device is of a vertical structure and sequentially comprises a device inlet (1), a waste heat boiler I, a pre-ash removal structure II, an SCR denitration reactor III and a device outlet (14) from top to bottom;

the waste heat boiler I comprises an evaporator (2), a superheater (3) and a boiler barrel (5); the boiler barrel (5) is respectively communicated with the evaporator (2) and the superheater (3); the outer vertical surface of the evaporator (2) and/or the superheater (3) is provided with a mechanical rapping device, and fly ash attached to heat exchange tubes in the evaporator (2) and/or the superheater (3) is removed through continuous rapping;

the pre-ash-removing structure II comprises a flue gas guide plate (6), an ash catcher (8) and a fly ash bin (15), wherein the flue gas guide plate (6) and the ash catcher (8) are oppositely arranged at the outlet end of the waste heat boiler I; the opening of the ash catcher (8) is upward and is arranged in a staggered way with the flue gas guide plate (6); the pipeline of the ash catcher (8) is communicated with an ash flying bin (15);

the SCR denitration reactor III comprises a catalyst module layer (11), wherein the catalyst module layer (11) is formed by combining a plurality of catalyst modules, the catalyst modules are of a porous penetrating structure, and smoke passes through holes of the catalyst modules to realize NO _x Removing;

high-temperature flue gas from the tail of the cement kiln enters an inlet (1) of the device, and is subjected to heat convection with a waste heat boiler I to generate superheated steam; the cooled flue gas enters a pre-ash-removing structure II, the flow is guided and segregated under the action of a flue gas guide plate (6), and fly ash in the flue gas enters an ash catcher (8) under the action of wind pressure and inertia forceThe flue gas from which part of the fly ash is removed is conveyed to a fly ash bin (15) by a pipeline and enters an SCR denitration reactor III to remove NO by the action of the SCR denitration reactor III _x The treated flue gas is discharged from the device outlet (14).

2. The kiln tail waste heat boiler and SCR denitration integrated device suitable for the cement kiln as defined in claim 1, wherein the evaporator (2) and the superheater (3) are both of box body structures, and the box body spaces of the box body structures are communicated with each other up and down for circulating flue gas; a first internal heat exchange tube is arranged in a box body of the evaporator (2), a second internal heat exchange tube is arranged in a box body of the superheater (3), and the boiler barrel (5) is communicated with the first internal heat exchange tube and the second internal heat exchange tube respectively.

3. The integrated kiln tail waste heat boiler and SCR denitration device suitable for the cement kiln as claimed in claim 2, wherein the first internal heat exchange tube and/or the second internal heat exchange tube are horizontally arranged.

4. The kiln tail waste heat boiler and SCR denitration integrated device suitable for the cement kiln as claimed in claim 2, wherein the box contact surface of the evaporator (2) and the superheater (3) is connected and sealed by adopting a welding process.

5. The kiln tail waste heat boiler and SCR denitration integrated device suitable for the cement kiln as claimed in claim 2, wherein the first inner heat exchange tube and/or the second inner heat exchange tube is suspended in the box body.

6. The integrated kiln tail waste heat boiler and SCR denitration device suitable for the cement kiln as defined in claim 1, wherein the flue gas guide plate (6) is of an inverted V-shaped angle steel structure.

7. The kiln tail waste heat boiler and SCR denitration integrated device suitable for the cement kiln according to claim 1, wherein an ash catching port of the ash catcher (8) is of an inverted quadrangular frustum pyramid structure, the tail end of the ash catching port is connected with a vertical pipeline, a plurality of vertical pipelines are connected with a first pipeline (9), and the first pipeline (9) is obliquely arranged and is used for collecting fly ash in the ash catcher (8) to one side of the device; the first pipeline (9) is connected with the fly ash bin (15) through a second pipeline (10).

8. The kiln tail waste heat boiler and SCR denitration integrated device suitable for the cement kiln as defined in claim 1, wherein a suspension device (13) is arranged on the side surface of the SCR denitration reactor III for the hoisting requirement of the catalyst module for failure replacement.

9. The integrated device of the kiln tail waste heat boiler and the SCR denitration suitable for the cement kiln is characterized by comprising a rake type soot blower (12), wherein a sweeping point of the rake type soot blower (12) is arranged on the upper surface of the catalyst module layer (11), and the soot flying bin (15) is arranged below the catalyst module layer (11).

10. The integrated device of the kiln tail waste heat boiler and the SCR denitration suitable for the cement kiln as claimed in claim 1, which comprises a spiral ash conveying device (16) in transmission connection with a fly ash bin (15).