Sintering flue gas reduction and waste heat comprehensive utilization method and device

Abstract

A sintering flue gas reduction and waste heat comprehensive utilization process is composed of flue gas circulating sintering, sinter vertical cooling, circulating air cooling, waste heat power generation and the like. The process comprises the following specific steps that part of sintering flue gas is guided out from a sintering trolley head and tail bellows branch pipes, and after dedusting and boosting, the flue gas is circulated to the surface of a middle material layer of a sintering trolley; sintering waste gas in the middle of the sintering machine trolley is guided out and subjected to dedusting and purification, most of the purified waste gas is emitted, and a small amount of waste gas takes participation in high-temperature sinter vertical cooling; the sinter at the tail end of the sintering trolley is crushed and then enters a vertical cooling furnace, counter flow cooling is conducted on the crushed sinter and circulating air blown from the bottom, and the sinter is discharged; the circulating cold air enters a waste heat power generation system after being subjected to heat exchange and primary dedusting; and the circulating air flowing through the waste heat power generation system is subjected to secondary dedusting and is mixed with part of purified sintering waste gas, boosting is conducted, and then the mixed gas enters the vertical furnace for hot ore circulating air cooling. According to the sintering flue gas reduction and waste heat comprehensive utilization process, the sintering flue gas and sinter sensible heat can be utilized effectively, the flue gas emission is cut down, pollutants such as dust, SO2, NOx and dioxin can be removed at the same time, the occupied space is small, and the investment is small.

Description

technical field [0001] The invention relates to the fields of energy saving, emission reduction and comprehensive pollution control, in particular, the invention relates to the reduction of sintering waste gas, the reduction of pollutants and the utilization of waste heat in the iron and steel metallurgical sintering process, as well as the efficient utilization of sensible heat of sinter and the cooling of sinter New technology for dust control in the process. Background technique [0002] Iron and steel metallurgy industry is a high energy consumption and high pollution industry. In 2014, my country's crude steel output was about 823 million tons, more than half of the global output. Sinter is the main charge for blast furnace ironmaking in my country, accounting for more than 70% of the iron charge in the furnace. In 2014, the national sinter output exceeded 700 million tons. [0003] After the sintering mixture is ignited, a large amount of sintering waste gas will be ...

AI Technical Summary

Problems solved by technology

[0009] The disadvantages brought by this process are: (1) the amount of exhaust gas discharged from the sintering main flue is large, resulting in high one-time investment and operating costs for subsequent dust removal and desulfurization facilities; The waste heat is lost after being directly discharged by utilization; (3) The removal rate of NOx, CO, dioxin and other pollutants in the sintering waste gas in the subsequent flue gas desulfurization facilities is low, and the chimney emissions may exceed the standard

[0013] (1) The trolley blows or extracts air during its movement, and the sealing problem between the trolley and the bellows is difficult to solve. Generally, the air leakage rate is more than 20%, or even as high as 50%;

[0014] (2) The two ends of the cooling machine cannot be sealed and a lot of wild wind is mixed in. Since the wild wind does not pass through the sintered material layer, it not only increases the power and power consumption of the fan, but also greatly reduces the smoke after heating. Gas temperature, under the condition of sinter temperature of 750°C, the flue gas temperature is generally only 250-350°C, and the flue gas drawn by the bellows in the front third of the cooler can reach 250-350°C. The flue gas cannot be used because the temperature is too low

The reason why this technical route is difficult for engineering application is that:

[0017] (1) The amount of sintering waste gas is large, and when the gas-to-material ratio (the ratio of gas volume to sinter mass) is too large, the temperature rise of the gas after heat exchange is limited, and it is difficult to meet the requirements of the follow-up waste heat power generation system for the smoke temperature;

[0018] (2) The negative pressure of the sintering waste gas from the main flue is as high as 15000Pa, and then boosted to overcome the resistance of the material layer in the shaft furnace, which puts forward very strict requirements on the fan, resulting in a sharp increase in fan power;

[0019] (3) The concentration of SO2 in the sintering waste gas is high, and contains corrosive components such as SO3, HCl, HF, etc., and it will directly enter the waste heat boiler without treatment, which will cause serious equipment corrosion

The disadvantages of this invention are: the sinter particles are coarse, the density is high, and the temperature is high, and the load-bearing, material, and wear requirements of the integrated device are high. At the same time, the efficiency of solid-liquid indirect heat exchange is low, and it is difficult to meet the production requirements of rapid cooling of sinter.

Its disadvantage is that complex structural parts are arranged in the body, which hinders the flow of high-temperature sintered minerals, and the hot ore is directly cooled without crushing, and the heat exchange time is long. The steam is difficult to meet the requirements of waste heat power generation

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