Pellet flue gas circulation and waste heat utilization process and system thereof

Patent metadata

Field	Value
Publication number	US-2023243586-A1
Application number	US-202318102107-A
Country	US
Kind code	A1
Filing date	Jan 27, 2023
Priority date	Jan 29, 2022
Publication date	Aug 3, 2023
Grant date	—

Abstract

The present application discloses a pellet flue gas circulation and waste heat utilization process and a system thereof, which relates to the technical field of flue gas treatment. The system includes a grate, a rotary kiln, an annular cooler, and ducts connecting each part. On the basis of not changing the existing process a flue gas circulation unit and intelligent control equipment are arranged additionally in the present application. The process is simple, and not only can ensure the parameter stability of the production system such as temperature, gas flow or gas pressure, but also can make full use of the low and medium temperature flue gas components and the waste heat, so as to achieve net zero waste gas discharging, energy saving and emission reduction.

First claim

What is claimed is:

1 . A pellet flue gas circulation and waste heat utilization process, which is carried out based on a pellet flue gas circulation and waste heat utilization system;
the pellet flue gas circulation and waste heat utilization system comprises a grate, a rotary kiln and an annular cooler; in the pellet feeding direction, the grate comprises a blast drying section, an extraction drying section, a first preheating section and a second preheating section in sequence, the annular cooler comprises a first annular cooling section, a second annular cooling section, a third annular cooling section and a fourth annular cooling section in sequence, and a head end of the rotary kiln is connected to the second preheating section of the grate, and a tail end of the rotary kiln is connected to the first annular cooling section of the annular cooler; an outlet of the first annular cooling section of the annular cooler is connected to an inlet of the rotary kiln through a duct, an outlet of the rotary kiln is connected to an inlet of the second preheating section of the grate through a duct, and an outlet of the second preheating section of the grate is connected to an inlet of the extraction drying section of the grate through a duct; an outlet of the second annular cooling section of the annular cooler is connected to an inlet of the first preheating section of the grate through a duct; an outlet of the third annular cooling section of the annular cooler is connected to inlets of the blast drying section and the extraction drying section of the grate through ducts, respectively; outlets of the extraction drying section and the first preheating section of the grate are connected to an inlet of the third annular cooling section of the annular cooler through ducts; an outlet of the blast drying section of the grate is connected to an inlet of the fourth annular cooling section of the annular cooler through a duct; an outlet of the fourth annular cooling section of the annular cooler is connected to inlets of the first annular cooling section and the second annular cooling section of the annular cooler through ducts, respectively; a continuous flue gas emission monitoring system and a control valve are arranged in the ducts between the blast drying section and the fourth annular cooling section, between the extraction drying section and the first preheating section and the third annular cooling section, and between the fourth annular cooling section and the first annular cooling section and the second annular cooling section; 50%-100% of the flue gas from the blast drying section is introduced into the fourth annular cooling section after dust removal; the flue gas introduced into the first annular cooling section and the flue gas introduced into the second annular cooling section from the fourth annular cooling section have a ratio of 0:1-1:0; the flue gas from the blast drying section after dust removal has a temperature of 80-150° C.; the flue gas from the extraction drying section and the first preheating section after desulfurization and denitrification has a temperature of 100-200° C.; the flue gas introduced into the first annular cooling section and the second annular cooling section from the fourth annular cooling section has a temperature of 100-200° C.; the flue gas introduced into the blast drying section and the extraction drying section from the third annular cooling section has a temperature of 250-350° C.; the flue gas from the blast drying section after dust removal has an oxygen content of 17-20%; the flue gas from the extraction drying section and the first preheating section after desulfurization and denitrification has an oxygen content of 12-18%; the flue gas introduced into the blast drying section and the extraction drying section from the third annular cooling section has an oxygen content of 17-20%; the flue gas introduced into the first annular cooling section and the second annular cooling section from the fourth annular cooling section has an oxygen content of 17-20%; dust removal equipment is further arranged between the blast drying section and the fourth annular cooling section; a desulfurization unit and a denitrification unit are further arranged in the duct from the extraction drying section and the first preheating section to the third annular cooling section; an SNCR system is further arranged on the top of the second preheating section or in an inlet duct of the second preheating section; an SCR system is arranged between the extraction drying section and the third annular cooling section.

Assignees

• Inst Process Eng Cas

Inventors

• Zhu Tingyu
• Xu Wenqing
• Xie Jun
• Li Chaoqun
• Wang Yixi

Classifications

• F27D17/20

  Arrangements for treatment or cleaning of waste gases · CPC title

• F27D17/10 Primary

  Arrangements for using waste heat · CPC title

• Y02P10/25

  Process efficiency · CPC title

• F27B7/20

  Details, accessories or equipment specially adapted for rotary-drum furnaces · CPC title

• F27B7/362 Primary

  Introducing gas into the drum axially or through the wall · CPC title