CN109160748B

CN109160748B - Method for preparing active magnesium oxide by staged combustion of gas magnesite

Info

Publication number: CN109160748B
Application number: CN201810928579.6A
Authority: CN
Inventors: 许光文; 韩振南; 程继光; 何伟; 刘雪景; 安萍; 王永生; 于泮杰
Original assignee: Shenyang University of Chemical Technology
Current assignee: Shenyang University of Chemical Technology
Priority date: 2018-08-15
Filing date: 2018-08-15
Publication date: 2021-06-08
Anticipated expiration: 2038-08-15
Also published as: CN109160748A

Abstract

A method for preparing active magnesium oxide by utilizing gas magnesite through staged combustion relates to a mineral product calcining method, in particular to a staged combustion method for preparing active magnesium oxide by utilizing gas magnesite conveying/suspension light combustion, which specifically comprises the following steps: the gas combustion required by the light combustion of magnesite powder is divided into multiple stages, wherein the first stage combustion is carried out in a gas combustor in front of a magnesite calciner, all the required combustion air is supplied from the first stage combustor, the excess air and high-temperature flue gas generated by the gas combustion enter the bottom of the magnesite powder calciner, and the gas combustion after the second stage is carried out by directly supplying the gas into the calciner from a proper position above the bottom of the calciner. The invention ensures the constancy of the temperature in the calcining furnace by utilizing the staged combustion of the fuel gas, reduces the generation amount of the flue gas, thereby ensuring the uniform quality and high activity of the light-burned magnesia and avoiding the problems of overburning and underburning.

Description

Method for preparing active magnesium oxide by staged combustion of gas magnesite

Technical Field

The invention relates to a mineral product calcining method, in particular to a method for preparing active magnesium oxide by utilizing gas magnesite through staged combustion.

Background

For decades, the apparatus for preparing light-burned magnesia by calcining magnesite at high temperature has been used for calcining magnesite by the traditional process of combining a water gas generator with a reverberatory furnace or a shaft kiln, wherein the method for preparing light-burned magnesia by calcining magnesite by the shaft kiln is generally adopted, but the method generally adopts large magnesite which is put into the kiln for calcination. Because the process does not have a constant temperature maintaining process, the magnesite blocks fed into the furnace are large, and the phenomenon of over-burning on the surface and under-burning in the center is easy to occur, the obtained light-burned magnesia has the defects of uneven quality, low activity and the like.

The existing Chinese patents relate to devices for calcining magnesite, such as boiling furnace light-burned magnesia (Chinese patent CN85108710), suspension furnace light-burned magnesia (Chinese patent CN85106397, 201020131767.5), rotary kiln light-burned magnesia (Chinese patent 200710011301.4, 90107753.4, 201710676058.1), tunnel kiln light-burned magnesia (Chinese patent 200610047061.9, 200510046995.6, 200910148368.1), reflection kiln light-burned magnesia (Chinese patent 201320654961.5), vertical kiln light-burned magnesia (Chinese patent 201610545960.5) and the like, which are researches on magnesite light-burned processes and devices, are improved on the basis of traditional reactors, cannot keep furnace temperature constancy, and are easy to cause magnesite over-burning or under-burning phenomena. While patents related to staged combustion include air staged combustion in boilers (CN 101832549B), pulverized coal staged combustion (CN 102887657A), gas staged combustion in suspension roasters (201710933892.4), etc., the gas fuel inlets mentioned in these patents related to staged combustion are all below the feed port, so as to reduce the emission of nitrogen oxides, and the stability of the furnace temperature cannot be effectively controlled.

In order to keep the constancy of the temperature in the calcining furnace, avoid the problems of overburning and underburning of magnesite and simultaneously avoid the emission of nitrogen oxides, the concept of gas staged combustion is introduced into the field of magnesite calcining, and the gas staged combustion is utilized to prepare active magnesium oxide.

Disclosure of Invention

The invention aims to provide a method for preparing active magnesium oxide by utilizing gas magnesite through staged combustion, which is a method for preparing active magnesium oxide through magnesite conveying/suspension light combustion of gas through staged combustion. The staged combustion of the fuel gas ensures the constancy of the temperature in the calcining furnace and reduces the generation amount of the flue gas, thereby ensuring the uniform quality and high activity of the light-burned magnesia and avoiding the problems of over-burning and under-burning.

The invention is realized by the following technical scheme:

a method for preparing active magnesium oxide by utilizing gas magnesite staged combustion divides gas combustion required by magnesite powder light combustion into multiple stages, wherein the first stage combustion is carried out in a gas combustor in front of a magnesite calcining furnace, required combustion air is completely supplied from the first stage combustor, the excess air and high-temperature flue gas generated by gas combustion enter the bottom of the magnesite powder calcining furnace, and the gas combustion after the second stage is carried out by directly supplying the gas into the calcining furnace from a proper position above a magnesite feeding port of the calcining furnace.

According to the method for preparing the active magnesium oxide by utilizing the staged combustion of the gas magnesite, the highest temperature of the high-temperature flue gas generated by the first-stage combustor is on the premise that the activity of a light-burned product generated by the action of the high-temperature flue gas and the flue gas in a magnesite powder calcining furnace is not remarkably reduced, such as the temperature is lower than 1200 ℃.

The method for preparing the active magnesium oxide by utilizing the gas magnesite staged combustion has the advantages that the staged combustion stage number is more than two stages, the height position of the gas fed into a magnesite powder calcining furnace after the two stages is selected, and the temperature in the calcining furnace at the position is lower than the temperature value which is difficult to keep the light combustion reaction speed, such as 800 ℃, as the basis; the amount of the fuel gas to be fed is limited so that the maximum temperature formed in the vicinity of the feeding position is not higher than the temperature at which the activity of the light burned product in the calciner is significantly reduced, for example, 1000 ℃.

In the method for preparing the active magnesium oxide by using the gas magnesite staged combustion, more than two stages of gas supply modes for the magnesite calcining furnace are based on the formation of uniform combustion and temperature distribution on the section and the prevention of local overtemperature, for example, the gas can be supplied from a plurality of gas supply ports which are symmetrically arranged.

The invention has the following advantages:

the staged combustion of the fuel gas ensures the constancy of the temperature in the calcining furnace and reduces the generation amount of the flue gas, thereby ensuring the uniform quality and high activity of the light-burned magnesia and avoiding the problems of over-burning and under-burning.

Drawings

FIG. 1 is a schematic illustration of example 1 of a process flow of the present invention;

FIG. 2 is a schematic illustration of example 2 of the process flow of the present invention;

FIG. 3 is a distribution diagram of the gas supply mode of the magnesite powder calcining furnaces in the process flow examples 1 and 2 of the invention on the cross section.

Detailed Description

In order that the objects, methods and advantages of the invention will become more apparent, the invention is further described in detail in the following description taken in conjunction with the accompanying drawings.

Example one

As shown in fig. 1, the gas is introduced into the combustor in front of the magnesite powder transporting/suspending calciner, so that the first stage combustion is carried out in the combustor, all the required combustion air is supplied from the first stage combustor, the excess air and high-temperature flue gas generated by the combustion of the gas enter the bottom of the magnesite powder transporting/suspending calciner, and the gas combustion in the second stage is carried out by directly supplying the gas into the calciner from above the bottom of the magnesite powder transporting/suspending calciner. The gas supply mode above the bottom of the calcining furnace is shown in figure 3, and gas supply ports are symmetrically arranged on the section of the calcining furnace; the hot flue gas generated by combustion is fully contacted with magnesite, the product of the hot flue gas is separated from light-burned magnesia powder of a solid product by a cyclone separator, the flue gas exchanges heat with raw material magnesite powder for cooling, and the flue gas is discharged after being filtered and dedusted to reach the standard; preheating air required by combustion by a product heat exchange system, feeding the preheated air into a combustor, and conveying the light-burned magnesium product subjected to heat exchange into a storage tank.

Example two

As shown in fig. 2, the gas is introduced into the burner before the magnesite powder conveying/suspending calciner, so that the first stage combustion is carried out in the burner, all the required combustion air is supplied from the first stage burner, the excess air and high-temperature flue gas generated by gas combustion enter the bottom of the magnesite powder conveying/suspending calciner, and the gas combustion of the second stage and the third stage is carried out by directly supplying the gas into the calciner from above the bottom of the magnesite powder conveying/suspending calciner. The gas supply mode above the bottom of the calcining furnace is shown in figure 3, and gas supply ports are symmetrically arranged on the section of the calcining furnace; the hot flue gas generated by combustion is fully contacted with magnesite, the product of the hot flue gas is separated from light-burned magnesia powder of a solid product by a cyclone separator, the flue gas exchanges heat with raw material magnesite powder for cooling, and the flue gas is discharged after being filtered and dedusted to reach the standard; preheating air required by combustion by a product heat exchange system, feeding the preheated air into a combustor, and conveying the light-burned magnesium product subjected to heat exchange into a storage tank.

Claims

1. A method for preparing active magnesium oxide by utilizing gas magnesite through staged combustion is characterized by comprising the following preparation processes:

the gas combustion required by the light combustion of magnesite powder is divided into multiple stages, wherein the first stage combustion is carried out in a gas combustor in front of a magnesite calciner, all the required combustion air is supplied from the first stage combustor, the excess air and high-temperature flue gas generated by the gas combustion enter the bottom of the magnesite powder calciner, and the gas combustion after the second stage is carried out by directly supplying the gas into the calciner from a proper position above the bottom of the calciner;

the highest temperature of high-temperature flue gas generated by the first-stage combustor is lower than 1200 ℃;

the stage number of the staged combustion is more than two stages, and the selection of the height position of the fuel gas fed into the magnesite powder calcining furnace after the two stages is based on that the temperature in the calcining furnace at the position is lower than 800 ℃; the amount of the fuel gas supplied is such that the maximum temperature formed near the supply position is not higher than 1000 ℃;

the gas supply mode of the magnesite powder calcining furnace with more than two levels is based on the formation of uniform combustion and temperature distribution on the cross section and the prevention of local overtemperature.