Chain grate machine-rotary kiln-circular cooler with ultra-low emission for sulfur fixation and denitration

Abstract

The utility model relates to a chain grate-rotary kiln-circular cooler with ultra-low emission for sulfur fixation and denitration, and belongs to the technical field of pellet production. The chain grate machine, the rotary kiln and the circular cooler are sequentially arranged according to the working procedure sequence, the chain grate machine is divided into a forced air drying section, an air draft drying section and a preheating section through two first partition walls, the preheating section is divided into a preheating section I and a preheating section II through a second partition wall, and the rotary kiln is in butt joint with the preheating section II; a preheating section II smoke exhaust pipe is arranged at the bottom of the preheating section II, the preheating section II smoke exhaust pipe is communicated with the air draft drying section through an air draft header pipe, and a multi-pipe dust remover, a denitration reactor and a backheating fan are sequentially arranged on the air draft header pipe; a preheating section I smoke exhaust pipe is arranged at the bottom of the preheating section I, and the first preheating section I smoke exhaust pipe close to the second partition wall is connected with an air draft header pipe. The flue gas waste heat utilization rate of the preheating section II can be increased, nitrogen oxide of the preheating section I can be reduced at the same time, and therefore emission of NOx at a main exhaust port of the chimney is reduced.

Description

Technical Field

[0001] This utility model relates to a chain grate machine-rotary kiln-ring cooler for desulfurization and denitrification with ultra-low emissions, belonging to the field of pellet production technology. Background Technology

[0002] Currently, the domestic pellet production generally adopts the chain grate machine-rotary kiln-annular cooler process. The chain grate machine is generally divided into four drying and preheating sections, in order of decreasing temperature: preheating section II, preheating section I, exhaust drying section, and forced-air drying section. Each section is separated by refractory walls, which are built from the arch downwards. During the production process, NOx is mainly generated in the rotary kiln, which is directly connected to preheating section II.

[0003] In traditional equipment, the three heat-resistant partition walls in the four zones mentioned above are typically built from top to bottom up to the surface of the grate bed (hereinafter referred to as the partition wall clearance height). Increasing the clearance height of the partition walls in the preheating stage II of the chain grate machine to ~800mm significantly improves the utilization rate of the flue gas heat in preheating stage II, giving the production line the potential for further production increases. However, with the increased clearance, NOx-containing flue gas that should have remained in preheating stage II will leak into preheating stage I. If preheating stage I does not perform denitrification treatment on the emitted flue gas and instead directly draws it to the chimney, it will undoubtedly increase the NOx content at the total flue gas discharge outlet. To avoid nitrogen oxides being directly emitted into the atmosphere and polluting the air, existing technologies typically perform SCR denitrification treatment on the flue gas discharged from preheating stage I before the main exhaust fan, and then send it into the desulfurization system for discharge. Because the temperature of some of the flue gas discharged from preheating stage I is relatively low, it is below the required temperature for denitrification treatment. To ensure effective denitrification, a heating device is usually installed before the SCR denitrification unit to reheat the flue gas discharged from the preheating stage I, so that the temperature of the flue gas discharged from the preheating stage I meets the temperature requirements of SCR denitrification. This increases energy consumption and greatly increases the daily operation and maintenance costs. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide a chain grate machine-rotary kiln-annular cooler system for desulfurization and denitrification that achieves ultra-low emissions without reheating or energy waste, in contrast to the aforementioned existing technologies. x Ultra-low emissions reduce energy consumption and lower daily operation and maintenance costs.

[0005] The technical solution adopted by this utility model to solve the above problems is as follows: a chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions. The chain grate machine, rotary kiln, and annular cooler are arranged sequentially according to the process sequence. The chain grate machine is divided into a forced-air drying section, a forced-air drying section, and a preheating section by two first partition walls according to the direction of conveying green balls on the grate bed. The preheating section is divided into preheating section I and preheating section II by a second partition wall. The rotary kiln is connected to preheating section II. The bottom of preheating section II has a preheating section II air box, and the preheating section II air box is equipped with... There are several preheating section II flue gas pipes, which are connected to the exhaust drying section through the exhaust main pipe. A multi-tube dust collector, a denitrification reactor, and a regenerating fan are sequentially installed on the exhaust main pipe. The bottom of the preheating section I has a preheating section I air box, on which several preheating section I flue gas pipes are installed. The first preheating section I flue gas pipe near the second partition wall is connected to the exhaust main pipe. The remaining preheating section I flue gas pipes are respectively connected to the main electrostatic precipitator. The main electrostatic precipitator is connected to the subsequent desulfurization system or to the chimney through the main exhaust fan.

[0006] The height of the bottom gap between the second partition wall and the grate bed is less than the height of the bottom gap between the first partition wall and the grate bed.

[0007] The bottom of the exhaust drying section has an exhaust drying section air box, the exhaust drying section air box is equipped with an exhaust drying section smoke pipe, and the exhaust drying section smoke pipe is connected to the main electrostatic precipitator.

[0008] The bottom of the blower drying section is equipped with a blower drying section air box, and the blower drying section air box is equipped with a blower drying section exhaust pipe, which is directly discharged to the atmosphere through the furnace hood fan.

[0009] The annular cooler includes annular cooling section 1, annular cooling section 2, annular cooling section 3, and annular cooling section 4. The heat exchange flue gas from annular cooling section 1 is introduced into the rotary kiln for reuse, the heat exchange flue gas from annular cooling section 2 is introduced into preheating section I for reuse, the heat exchange flue gas from annular cooling section 3 is introduced into the blower drying section for reuse, and the annular cooling section 4 is directly discharged into the atmosphere.

[0010] Compared with existing technologies, the advantages of this utility model are: a chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions reduces the gap height between the second partition wall and the grate bed between the preheating stage II and preheating stage I, thus reducing the escape of nitrogen oxides from preheating stage II to preheating stage I. The NO in the flue gas emitted from preheating stage I is reduced. x As the NO content increases, the first hot section I exhaust pipe near the second partition wall is connected to the denitrification reactor via a multi-tube dust collector to remove NO content. x The flue gas is mixed with the preheating stage II and then enters the denitrification reactor for denitrification.

[0011] This application can both improve the waste heat utilization rate of flue gas in the preheating stage II and reduce nitrogen oxides in the preheating stage I, thereby reducing NOx emissions from the total chimney outlet. x Emissions. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a chain grate machine-rotary kiln-ring cooler for desulfurization and denitrification with ultra-low emissions according to an embodiment of the present invention;

[0013] In the diagram: 1. Circular cooler; 2. Rotary kiln; 3. Chain grate machine; 4. Preheating section II; 5. Second partition wall; 6. Exhaust drying section; 7. First partition wall; 8. Preheating section I; 9. Blowing drying section; 10. Exhaust pipe of preheating section II; 11. Exhaust pipe of preheating section I; 12. Exhaust pipe of exhaust drying section; 13. Exhaust pipe of blowing drying section; 14. Main electrostatic precipitator; 15. Main exhaust fan; 16. Multi-tube dust collector; 17. Denitrification reactor; 18. Regenerating fan; 19. Main exhaust pipe. Detailed Implementation

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0015] like Figure 1 As shown in this embodiment, a chain grate machine-rotary kiln-annular cooler system for desulfurization and denitrification with ultra-low emissions is implemented. The chain grate machine 3, rotary kiln 2, and annular cooler 1 are arranged sequentially according to the process order. The chain grate machine 3 is divided into a forced-air drying section 9, a forced-air drying section 6, and a preheating section by two first partition walls 7, according to the direction of conveying green balls on the grate bed. The preheating section is further divided into preheating section I 8 and preheating section II 4 by a second partition wall 5. The rotary kiln 2 is connected to preheating section II 4. The bottom of the preheating section II 4 has a preheating section II air box, and the preheating section II air box is equipped with several preheating section II exhaust pipes 10 evenly spaced. The preheating section II exhaust pipes 10 are connected to the inlet of the multi-tube dust collector 16 through the exhaust manifold 19. The outlet of the multi-tube dust collector 16 is connected to the inlet of the denitrification reactor 17. The outlet of the denitrification reactor 17 is connected to the exhaust drying section 6 through the regenerating fan 18. The flue gas of the preheating section II 4 is collected in the exhaust manifold 19 and flows to the multi-tube dust collector 16 for dust removal. After being transported to the denitrification reactor 17 for denitrification treatment by the regenerating fan 18, it enters the exhaust drying section 6 for reuse. The bottom of the preheating section I 8 has a preheating section I air box, on which several preheating section I exhaust pipes 11 are arranged at even intervals. The first preheating section I exhaust pipe 11 near the second partition wall 5 is connected to the exhaust main duct 19, so that the flue gas from the first preheating section I exhaust pipe 11 is collected in the exhaust main duct 19 and flows together with the flue gas from the preheating section II to the multi-tube dust collector 16 and the denitrification reactor 17 before entering the exhaust drying section 6. The remaining preheating section I exhaust pipes 11 are connected to the main electrostatic precipitator 14, which is connected to the subsequent desulfurization system or to the chimney through the main exhaust fan 15.

[0016] The height of the reserved bottom gap between the second partition wall 5 and the grate bed is less than the height of the reserved bottom gap between the first partition wall 7 and the grate bed, which reduces the escape of nitrogen oxides from the preheating section II to the preheating section I, thereby reducing the NO emission from the preheating section II to the preheating section I. x Escape rate.

[0017] The bottom of the exhaust drying section 6 has an exhaust drying section air box, which is equipped with an exhaust drying section flue 12, and the exhaust drying section flue 12 is connected to the main electrostatic precipitator 14. The bottom of the forced air drying section 9 has a forced air drying section air box, which is equipped with a forced air drying section flue 13, and the forced air drying section flue 13 is directly discharged to the atmosphere through the furnace hood fan.

[0018] The ring cooler includes a first ring cooler, a second ring cooler, a third ring cooler, and a fourth ring cooler. The heat exchange flue gas from the first ring cooler is introduced into the rotary kiln 2 for reuse. The heat exchange flue gas from the second ring cooler is introduced into the preheating section I for reuse. The heat exchange flue gas from the third ring cooler is introduced into the blower drying section for reuse. The fourth ring cooler is directly discharged into the atmosphere.

[0019] During the denitrification process, the first preheating stage I flue gas pipe and the preheating stage II flue gas pipe merge into a multi-tube dust collector for dust removal. The flue gas, now merged into the exhaust duct, is then transported to the denitrification reactor via a regenerating fan for further denitrification treatment. The denitrification reactor is an SCR (Selective Catalytic Reduction) device, which is existing technology and will not be described in detail here. This denitrification method can treat more than 50% of the total flue gas volume. The treated flue gas flows to the exhaust drying section, and then is sent to the chimney or subsequent desulfurization system via the main electrostatic precipitator and the main exhaust fan.

[0020] The flue gas in the first preheating section I exhaust pipe near the second partition and the flue gas in the preheating section II with a higher temperature converge in the exhaust pipe, which meets the temperature requirements for high-temperature denitrification treatment. Denitrification can be carried out directly without reheat treatment, which reduces the operating cost of the rotary kiln chain grate machine.

[0021] In addition to the above embodiments, this utility model also includes other implementation methods. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of this utility model.

Claims

1. A chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions, characterized in that: The chain grate machine, rotary kiln, and annular cooler are arranged sequentially according to the process sequence. The chain grate machine is divided into a forced-air drying section, a forced-air drying section, and a preheating section by two first partition walls according to the direction of conveying green balls on the grate bed. The preheating section is divided into preheating section I and preheating section II by a second partition wall. The rotary kiln is connected to preheating section II. The bottom of preheating section II has a preheating section II air box, and the preheating section II air box is equipped with several preheating section II exhaust pipes. The preheating section II exhaust pipes are connected to the forced-air drying section through a main exhaust pipe. A multi-pipe dust collector is sequentially installed on the main exhaust pipe. The system includes a denitrification reactor and a regenerating fan. The bottom of the preheating section I has a preheating section I air box, on which several preheating section I exhaust pipes are installed. The first preheating section I exhaust pipe near the second partition wall is connected to the main exhaust pipe. The flue gas in the first preheating section I exhaust pipe near the second partition wall merges with the flue gas from the preheating section II, which has a higher temperature, into the exhaust pipe, meeting the temperature requirements for high-temperature denitrification. The remaining preheating section I exhaust pipes are connected to the main electrostatic precipitator, which is connected to the subsequent desulfurization system or to the chimney via the main exhaust fan. The height of the bottom gap between the second partition wall and the grate bed is less than the height of the bottom gap between the first partition wall and the grate bed.

2. The chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions as described in claim 1, characterized in that: The bottom of the exhaust drying section has an exhaust drying section air box, the exhaust drying section air box is equipped with an exhaust drying section smoke pipe, and the exhaust drying section smoke pipe is connected to the main electrostatic precipitator.

3. The chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions as described in claim 1, characterized in that: The bottom of the blower drying section is equipped with a blower drying section air box, and the blower drying section air box is equipped with a blower drying section exhaust pipe, which is directly discharged to the atmosphere through the furnace hood fan.

4. The chain grate machine-rotary kiln-annular cooler for desulfurization and denitrification with ultra-low emissions as described in claim 1, characterized in that: The annular cooler includes annular cooling section 1, annular cooling section 2, annular cooling section 3, and annular cooling section 4. The heat exchange flue gas from annular cooling section 1 is introduced into the rotary kiln for reuse, the heat exchange flue gas from annular cooling section 2 is introduced into preheating section I for reuse, the heat exchange flue gas from annular cooling section 3 is introduced into the blower drying section for reuse, and the annular cooling section 4 is directly discharged into the atmosphere.

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