CN112707656A

CN112707656A - Gas-fired active lime kiln

Info

Publication number: CN112707656A
Application number: CN202110191674.4A
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-02-20
Filing date: 2021-02-20
Publication date: 2021-04-27

Abstract

The invention relates to a gas-fired active lime kiln, belonging to the technical field of metallurgical equipment. The present invention changes the existing active lime kiln structure, and divides the shaft kiln into three parts of preheating, limestone transfer, air heat exchange and mechanical gas shaft kiln. The method can quantitatively calcine lime, and accurately control the preheating temperature of limestone in the preheating kiln and the calcining temperature in the calcining kiln; the activity of the produced lime is high and is generally 390-460; can reduce the over-burning rate and realize energy conservation and efficiency.

Description

Gas-fired active lime kiln

Technical Field

The invention relates to a gas-fired active lime kiln, which can be applied to metallurgical steel-making enterprises and belongs to the field of metallurgical equipment.

Background

At present, the kiln types for producing active lime by each steel enterprise are divided into two categories: the rotary kiln is adopted as one type, and the shaft kiln is adopted as the other type, such as a parallel flow type double-chamber shaft kiln, a double-beam type shaft kiln, an annular sleeve shaft kiln and the like. In the two types of kiln types, the rotary kiln generally comprises a cylinder body, a rolling ring, a transmission device and the like, the material added at the high end of the kiln body is moved along the axial direction while rolling along the circumferential direction by utilizing the rotation of the cylinder body, the material is subjected to countercurrent heat exchange with the fuel injected at the low end of the kiln body, the material is heated and fired in the moving process, and finally the material is output at the low end of the kiln body; the shaft kiln is characterized by an integrated structure, wherein a preheating zone, a calcining zone and a cooling zone are all arranged in a furnace body, materials are added from the upper part of the furnace body and then move from top to bottom, preheating, calcining and cooling are sequentially carried out, and a finished product is finally output from the lower part of the furnace body. The two kinds of processes for producing the active lime by the kiln are in a flow line form, are convenient to operate, but have the following defects: (1) the preheating temperature and the calcining temperature are difficult to control accurately; (2) due to the large limestone consumption, the limestone is easily subjected to uneven heating during calcination, so that the calcination time is too long, and the raw and overburning rate is high; (3) lime is output in a production line mode, and quantitative production cannot be realized; (4) the activity degree of the produced lime is low, and is generally 280-360.

Disclosure of Invention

The invention aims to provide a novel gas-fired active lime kiln which is applied to a steel-making enterprise, can change the current limestone calcining method and improve the profits of the steel-making enterprise.

The invention is realized by the following technical scheme. The existing shaft kiln is divided into 3 parts, namely a preheating part, a limestone transfer and air heat exchanger part and a mechanized gas shaft kiln part for calcining active lime, wherein the three parts can be separately placed on the ground or connected together to be combined in a vertical mode; the mechanized gas shaft kilns can be arranged in a row side by side according to the requirement, the number of the mechanized gas shaft kilns is determined according to the frequency of the steel-making furnace and the time required for calcining lime in one kiln, and the volume of the mechanized gas shaft kilns is determined according to the volume of limestone required for steel-making. The lime kiln completely separates the preheating and the calcining of the limestone, the limestone in the preheating kiln is weighed by a limestone transfer vehicle in the middle, then the limestone is added into a mechanical gas shaft kiln for quantitative firing, and the weight of the limestone is determined according to the lime weight required by steel making of a steel making furnace.

The first part of the novel lime kiln is a vertical preheating kiln, namely a polygonal vertical preheater matched with a rotary kiln at present, and preheaters in other forms can also be mainly characterized in that the temperature of high-temperature flue gas from a calcining kiln is higher than 1100 ℃, the high-temperature flue gas is preheated with air participating in gas combustion through an air heat exchanger firstly, the temperature of the high-temperature flue gas is reduced to 600-810 ℃, then the high-temperature flue gas enters the vertical preheating kiln to heat limestone in the preheating kiln, the temperature of the limestone is preheated to 600-810 ℃, the temperature of the limestone in the vertical preheating kiln is effectively controlled, the condition that the limestone is decomposed in advance in the preheating kiln due to overhigh temperature is avoided, the phenomenon of overburning lime in the calcining process is prevented, and the efficiency of the follow-up steelmaking process is influenced.

The second part is a limestone transfer and air heat exchanger part, the temperature of exhaust gas exhausted from the calcining kiln is up to 1100-1200 ℃, the heat exchanger exchanges heat between 1100-1200 ℃ high-temperature exhaust gas of the shaft kiln and air and fuel gas participating in combustion of the shaft kiln, the high-temperature exhaust gas of the shaft kiln is controlled to be 600-810 ℃, and then enters the preheating kiln to preheat limestone in the kiln, so that the preheating temperature of the limestone in the preheating kiln is accurately controlled to be 600-810 ℃, decomposition of preheated limestone is prevented, the overburning rate of the limestone during calcining is low, the activity of calcined lime is improved, and energy is saved. The limestone transfer part comprises a limestone transfer vehicle, a weighing meter, a distributing device and the like. The limestone transfer vehicle is responsible for weighing and receiving limestone for the preheating kiln, the weight of the limestone being dependent on the lime required by the steelmaking furnace, and feeding the limestone into the calcining kiln through the limestone transfer vehicle and the distributor.

The third part is a mechanized gas shaft kiln for calcining the active lime for steel making, a plurality of shaft kilns are arranged in parallel, and the number of the shaft kilns is determined according to the frequency of the steel making furnaces and the time required for calcining the lime in one kiln. The volume of the kiln is designed according to the lime used for smelting one-furnace steel, and a row of nozzles can be added for uniform heat supply, so that quantitative lime can be accurately calcined. The calcined hot lime is directly discharged into an active lime heat-preserving tank for steelmaking without being cooled, and is transported to a steel mill by an automobile and directly added into a steelmaking furnace for steelmaking. The time for starting lime calcination is advanced by a calcination period according to a steelmaking plan, when lime is calcined and the activity degree reaches the highest, lime is discharged into an active lime groove for steelmaking and immediately transported to a steel mill, and the amount of the produced active lime is matched with the amount of the active lime required by the steelmaking plan, so that the aim of calcining one kiln of active lime to smelt one furnace of steel is fulfilled.

The invention has the advantages that the novel gas-fired active lime kiln is provided, and the lime can be quantitatively calcined; the preheating temperature of limestone in the preheating kiln can be accurately controlled; the calcining temperature in the calcining kiln can be accurately controlled; the lime activity is improved, and the raw overburning rate is reduced; when the lime reaches the highest activity degree, hot lime is discharged, the hot lime discharged into the heat-insulating groove is immediately transported to a steel mill, and is directly added into a steel-making furnace for smelting, so that energy conservation and efficiency creation are realized.

Advantageous effects

(1) The heat of the calcined active lime can be brought into the steel making process, the temperature of the hot lime is 1100-1150 ℃, the time for making steel and making slag is advanced by 2-4 minutes in comparison with the time for making slag by adding cold lime in the steel making process by adding the lime with high temperature, the slag is thoroughly and well melted in the early stage of smelting, the slag melting process in the middle and later stages is greatly reduced, and the phenomenon of drying back of the slag in the middle and later stages can be reduced.

(2) More scrap steel can be added in the steelmaking process, and the average specific heat of lime is large and reaches 0.902KJ/Kg, and the heat contained in the lime at the temperature of 1100-1150 ℃ can melt more scrap steel. Taking a 100 ton converter added with 5 tons of hot lime at 1100 ℃ (the specific heat of the scrap is 0.698 KJ/Kg DEG C, the molten steel temperature is 1600 ℃), the amount of the scrap steel which can be added is 4.43 tons.

Detailed Description

Example one

Taking 100 tons of molten iron smelted by a domestic 100 tons of converter as an example, the average consumption of active lime is 6 tons, and the adding temperature is about 50 ℃. When the gas-fired active lime kiln in the method is used for calcining lime, the quantitative calcined limestone amount is 10.7 tons. In the specific firing process, 10.7 tons of limestone are added for calcination, so that 6 tons of active lime can be obtained, and the activity degree is detected to be 390-460 and is about 100 higher than that of lime calcined in a traditional lime kiln.

Claims

1. A gas burning type active lime kiln is composed of a preheating unit, a lime stone transferring and air heat exchanger, and a mechanical gas burning unit for calcining active lime, which can be arranged on ground or combined together in vertical mode.

2. The gas-fired active lime kiln of claim 1, wherein the lime is quantitatively calcined, and wherein the mechanized gas shaft kilns are arranged in a plurality of side-by-side rows as required, the number being determined by the frequency of the steel making furnace and the time required to calcine the lime in one kiln, and the volume being determined by the volume of limestone required for steel making.

3. The gas-fired active lime kiln as set forth in claim 1, wherein the preheating and calcining of the limestone are completely separated, the middle limestone transfer car weighing the limestone in the preheating kiln and then feeding it into the mechanized gas-fired shaft kiln for quantitative burning, the weight of the limestone being determined according to the weight of lime required for steel making.

4. The gas-fired active lime kiln according to claim 1, wherein the active lime is hot direct lime.

5. The gas-fired active lime kiln according to claim 1, wherein the activity of the calcined active lime is between 390 and 440.

6. The gas-fired active lime kiln according to claim 1, wherein the fuel gas may be natural gas, coal gas, a mixture of coal powder and air, or a mixture of several combustible substances, etc.