CN211823775U - Chain grate-rotary kiln-circular cooler with ultralow emission - Google Patents
Chain grate-rotary kiln-circular cooler with ultralow emission Download PDFInfo
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- CN211823775U CN211823775U CN201922489740.7U CN201922489740U CN211823775U CN 211823775 U CN211823775 U CN 211823775U CN 201922489740 U CN201922489740 U CN 201922489740U CN 211823775 U CN211823775 U CN 211823775U
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Abstract
The utility model relates to a chain grate-rotary kiln-circular cooler with ultra-low discharge, wherein the chain grate is divided into an air blast drying section, an air draft drying section, a preheating I section and a preheating II section by a first partition wall, and the rotary kiln is butted with the preheating II section front and back; a smoke exhaust pipe is arranged on an air box at the bottom of the preheating I section, and is connected to a main electric dust collector through a pipeline, and the main electric dust collector is connected with a chimney through a pipeline; a denitration reactor is arranged on an air exhaust pipeline of the air box at the bottom of the preheating section II; at least one second partition wall is arranged in the preheating section I, and flue gas flowing into the preheating section I from the preheating section II through the bottom gap of the first partition wall is guided downwards through the second partition wall and penetrates through the grate bed to enter a bottom air box of the preheating section I; preheat the tub of discharging fume of I section bottom bellows and set up the flue gas eduction tube as the branch road of discharging fume, the flue gas eduction tube is connected to the suction line who preheats II section bottom bellows to carry out the denitration reaction in leading-in suction line who preheats II section as required with the flue gas in preheating I section bottom bellows.
Description
Technical Field
The utility model relates to a grate-rotary kiln-circular cooler for pellet production.
Background
At present, the domestic pellet production generally adopts a grate-rotary kiln-circular cooler process. The chain grate machine is generally divided into 4 drying and preheating sections, which are respectively as follows according to the temperature sequence: preheating the second section, preheating the first section, exhausting and drying the first section, and blasting and drying the second section, wherein the sections are separated by a fire-resistant partition wall, and the fire-resistant wall is built downwards from the vault. In the production process, NOx is mainly generated in the rotary kiln directly connected with the preheating section II, and although the temperatures of the preheating section II and the preheating section I are high, no NOx is generated through experimental verification.
In the traditional process equipment, the 3 heat-resistant partition walls in the four areas are generally built from top to bottom to be 400mm away from the surface of a grate bed (the height of a gap of the partition walls for short later), namely 200mm away from a material layer. The chain grate machine has the defects that the temperature rise of a preheating I-section material layer is not enough and the temperature of a wind box is low frequently when the chain grate machine is used in partial areas due to the lower partition wall, so that the production capacity of a production line is influenced. Aiming at the defects, in recent years, a new chain grate has a new machine type of improving and preheating a partition wall between a second section and a first section (hereinafter referred to as a preheating partition wall of the second section), the gap height of the preheating partition wall of the second section is improved to 800-1500 mm from original 400mm, the utilization rate of the heat of the flue gas of the preheating partition wall of the second section is greatly improved, and the production line has the potential of further improving the production.
Under the low partition wall gap height of the traditional machine type, NOx generated in the rotary kiln is gathered in the preheating section II, and the flue gas in the preheating section II can be intensively treated by an SNCR + SCR method to realize ultralow NOx emission. However, under the height of the gap of the novel high partition wall, a certain part of flue gas directly enters the preheating section I from the preheating section II, so that the denitration method is difficult to realize the ultralow emission target of NOx. Therefore, it is necessary to develop a novel chain grate with a large partition wall gap height and a chain grate with a small partition wall gap height for self-tapping modification for ultra-low emission denitration modification.
The technological process of the chain grate machine, the rotary kiln and the circular cooler comprises the following steps:
as shown in figure 1, the heat source of the whole production system is from the combustion of pulverized coal of a rotary kiln burner, the generated high-temperature flue gas roasts hot balls in the rotary kiln, the hot balls enter a circular cooler from a kiln head for cooling, and the hot balls sequentially pass through a first circular cooling section, a second circular cooling section, a third circular cooling section and a fourth circular cooling section to generate finished balls. The hot air after heat exchange with the annular cooling section enters the rotary kiln from the kiln head, directly enters the preheating section II after being mixed with the flue gas generated by pulverized coal combustion, and is sent to the air draft drying section after material layer heat release and multi-tube dust removal. The hot air after heat exchange with the annular cooling 2 section enters the preheating I section from the arch top of the chain grate, is mixed with the flue gas of the air draft drying section after the heat release of the material layer, enters the main electric dust removal section and is finally discharged into a chimney. And the hot air after heat exchange with the ring cooling three sections enters a blast drying section and is directly discharged into the atmosphere. The air after heat exchange with the ring cooling four sections is directly discharged to the atmosphere.
Due to the fact that gaps of partition walls of the preheating section II are heightened, NOx-containing flue gas which originally stays in the preheating section II leaks to the preheating section I in a large amount, and therefore the ultra-low emission requirement of a total chimney cannot be met after denitrification treatment is carried out on the flue gas of the preheating section II; the existing process is to reheat the flue gas at the preheating section I to the SCR reaction temperature and then carry out SCR denitrification treatment, the energy consumption is high, the reheating process is contrary to the flue gas temperature drop direction of the whole process, serious reheating energy waste is generated, meanwhile, the flue gas temperature at the inlet of the main electric dust collector is possibly high, and the core concept of energy conservation and environmental protection is not met.
SUMMERY OF THE UTILITY MODEL
The purpose of this application is effectively to solve above-mentioned contradiction, realizes chimney total row mouth NOx's minimum emission under the condition of no reheat, no energy waste, has promoted the utilization ratio of flue gas waste heat simultaneously.
The utility model provides a technical scheme that above-mentioned problem adopted does: a chain grate-rotary kiln-circular cooler with ultra-low discharge is characterized in that the chain grate, the rotary kiln and the circular cooler are sequentially arranged according to working procedures, the chain grate is divided into a blast drying section, an air draft drying section, a preheating I section and a preheating II section by a first partition wall according to the direction of green pellets conveyed by a grate bed, and the rotary kiln is in front-to-back butt joint with the preheating II section; the bottom air box of the preheating I section is provided with a smoke exhaust pipe, the smoke exhaust pipe is connected to the main electric dust collector through a pipeline, and the main electric dust collector is connected with a chimney through a pipeline; and a denitration reactor is arranged on an exhaust pipeline of the air box at the bottom of the preheating section II.
The improvement of the invention is that at least one second partition wall is arranged in the preheating section I, and the flue gas flowing into the preheating section I from the preheating section II through the bottom gap of the first partition wall is guided downwards through the second partition wall and then passes through the grate bed to enter the bottom air box of the preheating section I; the denitration reactor is characterized in that a valve a is arranged on a smoke exhaust pipe of the air box at the bottom of the preheating section I, a smoke gas outlet pipe is arranged in front of the valve a and connected to a suction pipeline of the air box at the bottom of the preheating section II, a valve b is arranged on the smoke gas outlet pipe, and smoke gas in the air box at the bottom of the preheating section I can be guided into the suction pipeline of the preheating section II and enter the denitration reactor to perform denitration reaction when the valve b is opened.
Preferably, a top gap is reserved between the second partition wall and the vault, a bottom gap is reserved between the second partition wall and the grate bed, and the height of the bottom gap is smaller than the height of a gap between the first partition wall and the grate bed between the preheating section II and the preheating section I. Thereby further contributing to the flow guiding effect of the second partition wall on the flue gas containing NOx overflowing from the preheating section II into the preheating section I.
Preferably, a multi-pipe dust remover is arranged on an air exhaust pipeline of the bottom air box of the preheating section II, and the multi-pipe dust remover is positioned in front of the denitration reactor.
Preferably, the bottom air box of the induced draft drying section is also provided with a smoke exhaust pipe and is connected to the main electric dust collector through a pipeline.
Furthermore, a smoke exhaust pipe is also arranged on an air box at the bottom of the blast drying section, and the smoke exhaust pipe is directly discharged to the atmosphere through a furnace hood fan.
Further, an exhaust pipeline of the air box at the bottom of the preheating section II pumps the flue gas subjected to denitration treatment to the exhaust drying section through a regenerative fan to recycle waste heat.
Further, the ring cooling machine comprises a ring cooling first section, a ring cooling second section, a ring cooling third section and a ring cooling fourth section, wherein heat exchange flue gas of the ring cooling first section is introduced into the rotary kiln for recycling, heat exchange flue gas of the ring cooling second section is introduced into the preheating I section for recycling, and heat exchange flue gas of the ring cooling third section is introduced into the blast drying section for recycling.
Preferably, an ammonia supplementing pipeline is additionally arranged on a flue gas pipeline between the annular cooling second section 302 and the preheating first section, so that ammonia gas is supplemented into the preheating first section to promote tail gas denitration treatment of the preheating first section.
Compared with the prior art, the utility model has the advantages of: the gap height between the first partition wall and the grate bed between the preheating section II and the preheating section I is increased, so that the heat utilization rate of the flue gas of the preheating section II is improved. In addition, the problem that the content of NOx in the exhaust smoke of the preheating section I rises due to the increase of the gap height of the first partition wall is solved, a second partition wall is further arranged in the preheating section I and close to the first partition wall, gaps are kept among the second partition wall, the vault and the grate bed, and the gap height of the second partition wall and the grate bed is accurately controlled, so that the second partition wall can pour the (high-temperature) smoke of the preheating section I into the preheating section II as far as possible to be drained, the smoke penetrates through the grate bed to enter a bellows at the bottom of the preheating section I, and the nitrogen-containing smoke is introduced into an exhaust pipeline of the preheating section II through a smoke outlet pipe to be denitrated.
Drawings
FIG. 1 is a process flow diagram of a conventional grate-rotary kiln-circular cooler;
fig. 2 is a process flow chart of the grate-rotary kiln-circular cooler of the embodiment of the invention.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawing, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The embodiment discloses a chain grate-rotary kiln-ring cooler with ultralow emission, wherein the ultralow emission specifically means that the content of nitrogen oxides in flue gas discharged from a chimney is low, the chain grate 1, the rotary kiln 2 and the ring cooler 3 are sequentially arranged according to working procedures, the chain grate 1 is divided into an air blowing drying section 101, an air blowing drying section 102, a preheating I section 103 and a preheating II section 104 by a first partition wall 105 according to the direction of green pellets conveyed by a grate bed, and the rotary kiln 2 and the preheating II section 104 are in front-to-back butt joint.
And a smoke exhaust pipe is also arranged on the air box at the bottom of the blast drying section 101 and is directly discharged to the atmosphere through a furnace hood fan. The bottom windbox of the updraft drying section 102 is also provided with a smoke exhaust pipe 106 and is piped to the main dust collector 4. A smoke exhaust pipe 106 is arranged on an air box at the bottom of the preheating I section 103, the smoke exhaust pipe 106 is connected to the main electric dust collector 4 through a pipeline, and the main electric dust collector 4 is connected to a chimney through a pipeline; and a multi-pipe dust remover 5 and a denitration reactor 6 are arranged on an exhaust pipeline of the air box at the bottom of the preheating II section 104. And an exhaust pipeline of the air box at the bottom of the preheating II section pumps the flue gas subjected to dust removal and denitration treatment to the exhaust drying section 102 through a regenerative fan 7 for waste heat recycling.
The ring cooling machine 3 comprises a ring cooling first section 301, a ring cooling second section 302, a ring cooling third section 303 and a ring cooling fourth section 304, wherein heat exchange flue gas of the ring cooling first section 301 is introduced into the rotary kiln 2 for reuse, heat exchange flue gas of the ring cooling second section 302 is introduced into the preheating I section 103 for reuse, and heat exchange flue gas of the ring cooling third section 303 is introduced into the blast drying section 101 for reuse. Meanwhile, in order to promote denitration treatment, an ammonia supplementing pipeline is additionally arranged on a flue gas pipeline of the annular cooling two-section 302, so that ammonia gas is supplemented into the preheating I section, SNCR reaction is carried out at the higher temperature of the preheating I section, and NOx leaked to flue gas of the preheating I section in the preheating II section is further reduced.
A second partition wall 107 is arranged in the preheating section I, the second partition wall 107 is close to the first partition wall 105 of the preheating section II, a top gap is reserved between the second partition wall 105 and the vault, a bottom gap is reserved between the second partition wall 105 and the grate bed, and the height of the bottom gap is smaller than that of the first partition wall 105 of the preheating section II 104 and the grate bed. The flue gas which flows into the preheating section I from the preheating section II through the bottom gap of the first partition wall 105 is guided downwards through the grate bed by the second partition wall 107 and enters the bottom air box of the preheating section I;
a baffle valve a is arranged on a smoke exhaust pipe of the air box at the bottom of the preheating section I, a smoke outlet pipe 108 is arranged in front of the baffle valve a and connected to a suction pipeline of the air box at the bottom of the preheating section II, a baffle valve b is arranged on the pipeline of the smoke outlet pipe 108, and smoke in the air box at the bottom of the preheating section I can be guided into the suction pipeline of the preheating section II and enter the denitration reactor for denitration reaction in the state that the baffle valve b is opened and the baffle valve a is closed.
The utility model is suitable for a chain grate-rotary kiln pelletizing flue gas denitration of big partition wall space height
In the grate-rotary kiln process with the large partition wall gap height, because the first partition wall of the preheating section II is lifted, a large amount of flue gas containing NOx can flow into the preheating section I. And a second partition wall is additionally arranged in the preheating I section close to the preheating II section, the height of the bottom of the wall from the grate bed, the height of the wall body and the distance between the wall body and the two air boxes need to be accurately calculated and determined, and most of the blowby smoke enters the air boxes at the bottom of the preheating I section. A baffle valve a is additionally arranged on an original smoke exhaust pipe of an air box at the bottom of the preheating I section to cut off the original smoke exhaust pipeline (can be restored); a smoke outlet pipe and a baffle valve b are additionally arranged in front of the baffle valve a to a preheating II-section total smoke exhaust pipe (which can be closed); and the second partition wall is additionally arranged in a matched manner, so that most of NOx-containing flue gas leaked from the preheating section II can still enter the preheating section II exhaust pipeline under the relatively weak suction force of the regenerative fan. After the flue gas overflowing from the preheating section II and the flue gas overflowing from the preheating section I and the high NOx mixed gas completely preheating the section II purify dust through the multi-tube dust remover, the high NOx mixed gas enters the denitration reactor to generate SCR denitration reaction. The nitrogen content of the flue gas discharged into the chimney can be reduced as much as possible by the operation means.
Although the preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that modifications and variations of the present invention are possible to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A chain grate-rotary kiln-circular cooler with ultra-low discharge is characterized in that the chain grate, the rotary kiln and the circular cooler are sequentially arranged according to working procedures, the chain grate is divided into a blast drying section, an air draft drying section, a preheating I section and a preheating II section by a first partition wall according to the direction of green pellets conveyed by a grate bed, and the rotary kiln is in front-to-back butt joint with the preheating II section; the bottom air box of the preheating I section is provided with a smoke exhaust pipe, the smoke exhaust pipe is connected to the main electric dust collector through a pipeline, and the main electric dust collector is connected with a chimney through a pipeline; a denitration reactor is arranged on an air exhaust pipeline of the air box at the bottom of the preheating II section;
the method is characterized in that: at least one second partition wall is arranged in the preheating section I, and flue gas flowing into the preheating section I from the preheating section II through the bottom gap of the first partition wall is guided downwards through the second partition wall and penetrates through the grate bed to enter a bottom air box of the preheating section I;
the denitration reactor is characterized in that a valve a is arranged on a smoke exhaust pipe of the air box at the bottom of the preheating section I, a smoke outlet pipe is arranged in front of the valve a and connected to a suction pipeline of the air box at the bottom of the preheating section II, a valve b is arranged on the smoke outlet pipe, and smoke in the air box at the bottom of the preheating section I is guided into the suction pipeline of the preheating section II and enters the denitration reactor to perform denitration reaction when the valve b is opened.
2. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: and a top gap is reserved between the second partition wall and the vault, a bottom gap is reserved between the second partition wall and the vault, and the height of the bottom gap is smaller than the height of a gap between the first partition wall and the grate bed between the preheating section II and the preheating section I.
3. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: and a multi-pipe dust remover is arranged on an air exhaust pipeline of the air box at the bottom of the preheating section II, and the multi-pipe dust remover is positioned in front of the denitration reactor.
4. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: and the bottom bellows of the air draft drying section is also provided with a smoke exhaust pipe, and the smoke exhaust pipe is connected to the main electric dust collector through a pipeline.
5. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: and the bottom air box of the blast drying section is also provided with a smoke exhaust pipe and is directly discharged to the atmosphere through a furnace hood fan.
6. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: and the exhaust pipeline of the air box at the bottom of the preheating II section pumps the flue gas subjected to denitration treatment to the exhaust drying section through a regenerative fan to recycle the waste heat.
7. The ultra-low emission grate-kiln-ring cooler of claim 1, wherein: the ring cooling machine comprises a ring cooling first section, a ring cooling second section, a ring cooling third section and a ring cooling fourth section, wherein heat exchange flue gas of the ring cooling first section is introduced into the rotary kiln for recycling, heat exchange flue gas of the ring cooling second section is introduced into the preheating I section for recycling, and heat exchange flue gas of the ring cooling third section is introduced into the blast drying section for recycling.
8. The ultra-low emission grate-kiln-ring cooler of claim 7, wherein: an ammonia supplementing pipeline is additionally arranged on a flue gas pipeline between the annular cooling two-stage section (302) and the preheating I section, so that ammonia gas is supplemented into the preheating I section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922489740.7U CN211823775U (en) | 2019-12-31 | 2019-12-31 | Chain grate-rotary kiln-circular cooler with ultralow emission |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922489740.7U CN211823775U (en) | 2019-12-31 | 2019-12-31 | Chain grate-rotary kiln-circular cooler with ultralow emission |
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| Publication Number | Publication Date |
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| CN211823775U true CN211823775U (en) | 2020-10-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201922489740.7U Active CN211823775U (en) | 2019-12-31 | 2019-12-31 | Chain grate-rotary kiln-circular cooler with ultralow emission |
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| CN (1) | CN211823775U (en) |
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- 2019-12-31 CN CN201922489740.7U patent/CN211823775U/en active Active
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