CN115218667A

CN115218667A - Gas flow decreasing intermittent injection auxiliary sintering method

Info

Publication number: CN115218667A
Application number: CN202111390071.3A
Authority: CN
Inventors: 王业峰; 叶恒棣; 魏进超; 周浩宇; 陈思墨; 李谦; 刘前
Original assignee: Zhongye Changtian International Engineering Co Ltd
Current assignee: Zhongye Changtian International Engineering Co Ltd
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2022-10-21
Anticipated expiration: 2041-11-22
Also published as: CN115218667B

Abstract

A method for auxiliary sintering by intermittent injection with decreasing gas flow is characterized in that: the method comprises the following steps of (1) periodically and intermittently injecting gas to the charge level of a sintering mixture, wherein the flow of the injected gas in each period is reduced gradually along with the increasing of the number of injection periods, and the gas enters a sintering charge layer to be combusted and supplied with heat; and in the process of gas injection, the temperature of the sintering ore zone and the combustion zone area in the sintering material layer is controlled by adjusting the gas injection flow in each period. The invention can realize accurate control of the upper temperature of the combustion zone in each sintering period and ensure that the red layer is not thickThe technical problems of overhigh and proper bed permeability, especially gradual thickening of red bed in the middle and later period of sintering, worsening of the bed permeability, continuous rising of negative pressure of sintering air draft and the like are obviously improved, so that more fuel gas is supplemented in the sintering process, and a larger proportion of solid fuel substitution and CO can be realized ₂ And (5) emission reduction.

Description

Gas flow decreasing intermittent injection auxiliary sintering method

Technical Field

The invention relates to a gas injection auxiliary sintering process, in particular to a gas flow decreasing intermittent injection auxiliary sintering method, and belongs to the technical field of sintering.

Background

Due to CO ₂ And due to greenhouse effect caused by gases, glaciers melt, sea level rises, natural ecology degeneration and natural disasters frequently occur, and the lives of human beings in partial regions are directly threatened. Along with the annual increase of the steel yield in China, the total carbon emission of the steel industry in China is on the trend of increasing year by year, the annual carbon emission is more than ten thousand, and CO in the steel industry ₂ Emission reduction tasks face tremendous pressure.

As a key link in the iron-making process in the iron and steel industry, the sintering process mainly has the main functions of mixing various powdery iron-containing raw materials with proper amount of fuel and flux, adding proper amount of water, mixing and pelletizing, enabling the materials to generate a series of physical and chemical changes on sintering equipment, sintering the materials into blocks, and conveying the blocks to a blast furnace for the next working procedure.

According to the relevant data, the carbon dioxide emission of sintering and blast furnace processes accounts for about 60% of the total industrial emission. In order to reduce carbon emission in the sintering process and the subsequent blast furnace smelting cost, the blast furnace usually has high strength and high reducibility on sintered ores. In the sintering process, the sintered ore is generally required to have higher strength, high yield, lower return fines rate and lower fuel consumption. The high-strength and high-reducibility sintered ore consumes less coke in the blast furnace smelting process, thereby reducing the emission of carbon dioxide.

After the pulverized coal of the upper material layer is ignited in the sintering process, the combustion heat release is not only used for sintering nearby raw materials, but also for air draft type operation production, the self-heat storage effect enables the heat of the upper part to be brought into the lower material layer by gas to participate in the sintering of the lower material layer, so that the heat required by the material layer from top to bottom is gradually reduced. Segregation distribution is adopted during distribution, the amount of coal powder distributed on the upper material layer is large, and the amount of coal powder distributed on the lower material layer is small. The method can greatly improve the quality index of the finished product under the same fuel consumption index, or greatly reduce the fuel consumption index under the same finished product quality index, thereby achieving the purposes of saving energy and reducing carbon emission.

However, due to the limitation of the device technology, in the current sintering plant, in the actual industrial production, the strict ideal layered segregation type fuel distribution is difficult to realize, and the owner has to allocate the solid fuel according to the high value of the theoretical required fuel quantity in each layer. Meanwhile, some large-particle coke powder can roll down to the bottom of the material layer when the sintering machine head distributes the material, and the opposite situation that the lower solid fuel quantity is high and the middle and upper solid fuel quantity is low can be caused. The problem that the upper material layer heat is insufficient and the middle and lower material layers heat is excessive can be caused in the sintering material layer during sintering production, the lower sintering material is easy to melt, and the like, so that energy and resource waste is caused and the generation of smoke pollutants is greatly intensified.

Under the large environment, the technology of 'sintering charge level gas fuel injection' developed by the Japan JFE company comes into force, natural gas fuel diluted to be below the lower limit of combustible concentration is injected above the sintering charge level at a distance behind an ignition furnace, and is combusted and supplied heat in a sintering charge layer, so that the solid carbon consumption and CO in the production of sintering ore are reduced ₂ And (4) discharging the amount. Meanwhile, the combustion of the gas fuel widens the width of the high-temperature belt of the sinter bed during production, so that 1200E to EThe temperature time of the sintered ore at 1400 ℃ is prolonged, so that the strength and the porosity of 5-10 mm of the sintered ore are effectively enhanced.

In the initial sintering process, the material layer distribution in the sintering process is shown in fig. 3, and the material layers on the trolley mainly comprise a sintering ore belt, a combustion belt, a drying preheating belt, an over-wet belt and an original material belt from top to bottom in sequence, wherein the approximate temperature distribution is shown by a curve corresponding to 'no blowing' in fig. 4. The burning zone is at a high temperature because the coke powder in the sintering material layer is ignited, the physicochemical processes of melting, sintering and the like of minerals are realized at 1200-1400 ℃, finished sintering ore is formed (the burning zone is changed into a sintering ore zone), and the burning of the coke powder is finished at the moment. Due to the influence of the air draft, fresh air is continuously supplemented to the top of the material bed to cool the material bed, so that the temperature of the sinter band is low at a position close to the top of the material bed and high at a position close to a combustion zone.

After the gas injection technology is adopted, the combustion of the gas fuel widens the width of a high-temperature zone of a sinter bed during production, and slows down the cooling speed of fresh air on sintered finished ore, so that the temperature of the position, close to a combustion zone, in the sinter ore zone is higher than that of the sinter ore zone without injection, and the effect is shown as a curve corresponding to injection in figure 4. The laboratory research and sintering process engineering practice shows that in a certain range, the larger the gas injection amount and the injection concentration are, the more heat released after the gas is absorbed into a material layer is, the larger the substituted solid fuel amount is, and therefore the lower coke consumption and CO are realized ₂ And (5) discharging. Generally, the higher the combustible gas concentration in the mixed gas is, the lower the ignition temperature is, and therefore, it can be found from the temperature distribution in the charge bed that, after increasing the injection amount of the gas and increasing the injection concentration, the position where the gas ignites in the charge bed moves from a position near the burning zone to the direction of the burning zone, and the temperature profile in the charge bed shows that the temperature is higher at the position near the burning zone as shown by the broken line in fig. 5.

The 'red layer' is used for describing the area with the temperature in the sintering material layer being above about 1000 ℃, obviously, after the gas injection amount is increased, the thickness of the red layer in the material layer is obviously increased, and because the temperature in the red layer is high and liquid phase is generated, the excessively thick red layer can cause poor air permeability of the material layer and overlarge negative pressure of sintering air draft, influence the air quantity passing through the material layer and the sintering process, and reduce the yield and quality of sintering ore. This phenomenon shows more obviously than sintering earlier stage in the middle and later stages of the supplementary sintering of gas jetting, the reason is along with the progress of sintering, the gas gets into the burning of bed of material and releases a large amount of heat, solid fuel-fine coke burning in the bed of material releases a large amount of heat simultaneously, even reduce the ratio of solid fuel, after sintering carries out a period of time, the position near sintering ore deposit area and burning zone can receive bed of material upper portion heat accumulation, this regional jetting gas, the heating of this regional solid fuel, corresponding after fine coke and gas burning sintering back, the cooling rate in this region is compared littleer in the sintering initial stage, consequently, form thicker red layer, make the middle and later stages of sintering change the bed of material gas permeability relatively poor, the too big phenomenon of sintering convulsions negative pressure that appears.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a gas flow decreasing intermittent injection auxiliary sintering method. The invention aims to solve the technical problems of poor material layer air permeability, negative pressure rise of sintering air draft and the like after the gas injection quantity is improved in the gas injection auxiliary sintering process, and realizes the maximum gas injection quantity under the condition of maintaining the material layer air permeability and the air draft negative pressure to be normal, thereby more obviously improving the solid fuel substitution quantity and reducing CO ₂ And (5) discharging.

The present invention provides a method for continuously injecting gas, which changes the original method for continuously injecting gas in the gas injection process, but uses the measure of gas flow decreasing intermittent injection on the premise of maintaining the original gas supplement amount, and injects the gas into the material layer of the sintering mixture intermittently in time and gradually decreases in flow. The invention skillfully controls the injection and stop of the fuel gas by the fuel gas flow decreasing and intermittent injection, and enables the fuel gas to be ignited and extinguished repeatedly near the combustion zone, thereby ensuring that an excessively thick red layer caused by overhigh temperature can not appear at the positions of the combustion zone and the sintering ore zone, and effectively avoiding the technical problems of poor material bed air permeability, negative pressure rise of sintering air draft and the like. Meanwhile, along with the increasing of the number of the injection cycles, the flow of the injected gas is decreased progressively, so that the problems that the red layer is thickened and the material layer is poor in air permeability more easily at the middle and later stages of sintering are improved pertinently.

According to the embodiment of the invention, a method for sintering assisted by intermittent injection with decreasing gas flow is provided.

The intermittent blowing auxiliary sintering method with gradually decreased gas flow includes intermittent blowing gas to the material surface of the mixture to be sintered, gradually decreasing the gas flow rate in each period with the increasing of the blowing period number, and burning the gas in the material layer to heat. And in the process of gas injection, the temperature of the sintering ore zone and the combustion zone area in the sintering material layer is controlled by adjusting the gas injection flow in each period.

The "injected gas flow rate" in the "injected gas flow rate decreases in each period" and the "gas injection flow rate" in the "gas injection flow rate by adjusting in each period" herein mean the injection amount of gas per unit time.

Along the thickness direction of the sinter bed, the sinter bed on the sintering trolley mainly comprises a sinter ore zone, a combustion zone, a drying preheating zone, an over-wet zone and an original material zone from top to bottom in sequence.

In the present invention, the number of cycles of blowing the gas to the sinter mix in the sintering pallet is set to N. In the process of gas injection, the period of gas injection is sequentially 1 st period, 2 nd period \8230 \ 8230and Nth period, and the gas flow rate correspondingly injected in each period is sequentially S ₁ ，S ₂ ……S _N . Wherein S is ₁ ＞S ₂ ＞……＞S _N 。

In the invention, the time length of gas injection in a single period is set to be delta t ₁ Therefore, the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is required for sintering mixture in the sintering trolleyTotal amount of gas to be injected. And N is the cycle number of gas injection for the sintering mixture in the sintering trolley. S. the _i The flow rate of the gas injection in the ith period is obtained.

In the present invention, the gas injection flow rate S in the i-th cycle _i Comprises the following steps:

S _i ＝a·i+b…………(2)。

in the formula: a. and b is a gas injection flow regulating constant.

In the invention, the control of the temperature of the sintering ore zone and the combustion zone area in the sintering material layer comprises the following steps:

1) And determining the cycle number of the injected gas, the time length of the injected gas in a single cycle and the time length of the gas injection stopping in the single cycle.

2) And determining the initial gas injection flow in each period according to the total gas amount to be injected by the sintering mixture in the sintering trolley.

3) And in the gas injection time of the ith period, calculating the heat released by the injected gas in the sintering material layer, and calculating the heat storage quantity of the sintering material layer at the gas combustion position.

4) And calculating the cooling capacity of the air to the sinter bed in the gas blowout stopping time of the ith period.

5) And judging the temperature change condition of the sinter bed in the ith period according to the heat released by the combustion of the injected gas, the heat storage capacity of the sinter bed on the position where the sinter bed is combusted by the gas and the cooling capacity of air to the sinter bed, and further realizing the control of the temperature of the sinter band and the combustion band area in the sinter bed.

In the present invention, step 1) comprises the following substeps:

1a) Calculating the operation time t of the sintering pallet in the gas injection section according to the length L of the gas injection section on the sintering machine and the operation speed v of the sintering pallet, namely the total time t for injecting gas into the sintering mixture in the sintering pallet is as follows:

1b) Setting the number of cycles for injecting gas into the sintering mixture in the sintering trolley to be N and the time length for injecting gas in a single cycle to be delta t ₁ Whereby the duration of gas injection cut off in a single cycle is Δ t ₂ Comprises the following steps:

in the invention, in step 2), the total amount of gas to be injected into the sintering mixture in the sintering pallet is as follows:

in the formula: g is the total amount of gas required to be blown by the sintering mixture in the sintering trolley. And m is the mass of the sintering mixture in the corresponding area of the gas injection section. Q _{Supplement device} The heat quantity is needed to be supplemented for the sintering mixture of unit mass after the solid fuel proportioning is reduced integrally. Wherein Q is _{Supplement device} Is determined by the types of sintering raw materials, the average particle size of sintering mixture, the solid fuel ratio and the like. H is the heat value of the fuel gas.

Preferably, the determining of the initial gas injection flow rate in each period specifically includes: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow rate adjustment constants a, b are set ₀ 、b ₀ And satisfy

Thus obtaining the following components:

initial gas injection flow S in the 1 st cycle ₁ ＝a ₀ +b ₀ 。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ 。

……

Initial gas injection flow S in the ith period _i ＝a ₀ ×i+b ₀ 。

……

Initial gas injection flow S in Nth period _N ＝a ₀ ×N+b ₀ 。

In the present invention, in step 3), the calculating the heat released by the combustion of the injected gas in the sintering bed in the gas injection time of the ith period specifically includes:

Q _in，i ＝S _i ·Δt ₁ ·H＝(a ₀ ·i+b ₀ )·Δt ₁ ·H............(6)。

in the formula: q _in，i The heat released by the combustion of the injected gas in the ith period.

In the invention, in step 3), the calculating the heat storage amount of the upper material layer on the sinter bed at the corresponding position in the ith period specifically includes:

Q _x，i ＝10.72i ⁹ -545i ⁸ +11916.97i ⁷ -146417.39i ⁶ +1105050i ⁵ -5257230i ⁴ +15612800i ³ -27524500i ² +26912800i-10713900............(7)。

in the formula: q _x，i The sintered material layer is subjected to the heat storage amount of the upper material layer at the combustion position of the gas in the ith period.

The formula (7) is an empirical formula, at the corresponding position of the gas injection in the ith period, the sinter bed is subjected to heat transfer by the airflow above and heat conduction by the sinter bed to form corresponding heat storage, and the corresponding heat storage amount can be calculated through the formula (7).

In the invention, in step 4), the cooling amount of the air to the sinter bed is calculated within the gas blowout stop time of the ith period, specifically: gas blowout stopping time delta t in ith period ₂ The cooling rate of the sinter bed by air cooling is q _co，i Namely, the following steps are provided:

q _co，i ＝h _co ·(T _{combustion of i} -T _∞ )·ξ·m·A............(8)。

Q _co，i ＝q _co，i ×Δt ₂ ............(9)。

In the formula：Q _co，i The cooling quantity of the air to the sinter bed in the ith period is calculated. h is _co The cooling coefficient of the sinter bed is determined empirically, h _co The value range of the (B) is 50-60W/(m < 2 >. Cndot.). T is _∞ The air temperature is, for example, 30 ℃, 25 ℃, or 20 ℃. And m is the quality of the sintering mixture in the corresponding area of the gas injection section. A is the specific surface area of the combustion zone in the sintering material layer. Xi is the proportion of the combustion zone in the height direction to the height of the whole sinter bed, and the value range of xi is 0-1, preferably 0.01-0.1. T is _{Combustion of i} The combustion temperature of the fuel gas in the sintering material layer is gradually increased along with the increase of the period number i, and is generally in the range of 1200-1400 ℃, and an empirical formula T can be used _{Combustion of i} ＝1005+32.5ln(e ⁱ +i ² + 503.2).

In the present invention, step 5) comprises the following substeps:

5a) According to the heat balance principle, calculating the temperature change value delta T of the sinter bed at the gas combustion position in the ith period _i ：

c _p .ξ·m.ΔT _i ＝Q _in，i +Q _x，i -Q _co，i ............(10)。

Namely have

In the formula: c. C _p Is the average specific heat capacity of the sinter layer. Q _x，i The sintering material layer is subjected to the heat storage amount of the upper material layer at the gas combustion position of the ith period.

5b) Calculating the actual final temperature Tco, i of the sintering material layer at the corresponding position in the ith period:

T _co，i ＝T _{combustion of i} +ΔT _i ............(12)。

5c) Comparing the actual final temperature T of the sinter bed in the ith period _co，i With a target temperature T _aim Adjusting the gas injection flow adjusting constants a and b, and further adjusting the gas injection flow in the ith period, thereby realizing the temperature of the sintering ore zone and the combustion zone area in the sintering material layerAnd (5) controlling.

In the present invention, the substep 5 c) is specifically:

if the actual final temperature T of the sinter bed in the ith period _co，i = target temperature T _aim And controlling the temperature of the sintering zone and the combustion zone within a normal range in the period, and keeping the current injection parameters of the system to continue to operate.

If the actual final temperature T of the sinter bed in the ith period _co，i >Target temperature T _aim At the moment, the gas injection flow rate adjusting constants a and b are adjusted, so that the gas injection flow rate in the ith period is reduced, and T is enabled _co，i ＝T _aim 。

If the actual final temperature T of the sinter bed in the ith period _co，i <Target temperature T _aim Adjusting the gas injection flow rate adjusting constants a and b, and increasing the gas injection flow rate in the ith period to ensure that T is equal to _co，i ＝T _aim 。

Preferably, in sub-step 5 c), said target temperature T _aim The value range of (A) is 600-1000 ℃, preferably 700-850 ℃, and more preferably 740-780 ℃.

Generally, in the initial sintering process, the material layers in the sintering process mainly comprise a sintering ore belt, a combustion belt, a drying preheating belt, an over-wet belt and an original material belt from top to bottom in sequence. Wherein, the burning zone has higher temperature because the coke powder in the sintering material layer is ignited, the physicochemical processes of melting, sintering and the like of minerals are realized at 1200-1400 ℃, the finished product sintering ore is formed, namely, the burning zone is converted into a sintering ore zone, and the burning of the coke powder is finished at the moment. Due to the influence of air suction in the air suction type sintering, fresh air can be continuously supplemented to the top of the material layer to cool the material layer, so that the temperature of the sintering ore zone is low at a position close to the top of the material layer and high at a position close to a combustion zone.

In the prior art, to reduce CO during sintering ₂ The technology of gas injection auxiliary sintering is provided. Blowing gas fuel diluted to below the lower limit of combustible concentration above the sintering charge level to make it in the sintering charge layerInternal combustion heat supply is adopted, so that the solid carbon consumption and CO in the sinter production are reduced ₂ And (4) discharging the amount. In fig. 4, the temperature distribution of the sinter layer in the sintering process is compared between the case of using the gas injection technique and the case of not using the gas injection technique. The temperature distribution of the sinter bed not adopting the gas injection technology in the sintering process is shown by a curve corresponding to 'not adopting injection' in fig. 4, and the temperature distribution of the sinter bed adopting the gas injection technology is shown by a curve corresponding to 'adopting injection' in fig. 4. According to fig. 4, it can be seen that, after the gas injection technology is adopted, the combustion of the gas fuel widens the width of the high-temperature zone of the sinter bed during production, and slows down the cooling speed of fresh air on the sintered finished ore, so that the temperature in the sinter ore zone close to the combustion zone is higher than that when the injection is not adopted.

For further reduction of CO ₂ The laboratory research and the sintering process engineering practice find that in a certain range, the larger the gas injection amount and the higher the injection concentration are, the more the heat released after the gas is absorbed into a material layer is, the larger the substituted solid fuel amount is, so that the less coke consumption is realized, namely, the less CO is realized ₂ And (5) discharging. The temperature distribution of the sinter bed after increasing the injection amount of the fuel gas and increasing the injection concentration is shown by the dotted line in fig. 5. As can be seen from fig. 5, after the injection amount of the fuel gas is increased and the injection concentration is increased, the ignition position of the fuel gas in the material bed moves from the position near the burning zone to the direction of the burning zone, that is, the temperature of the burning zone is higher. The 'red layer' is used for describing the region with the temperature in the sintering material layer being above about 1000 ℃, obviously, after the gas injection amount is increased, the thickness of the red layer in the material layer is obviously increased, and because the temperature in the red layer is high and liquid phase is generated, the excessively thick red layer can cause poor air permeability of the material layer and overlarge negative pressure of sintering air draft, influence the air quantity passing through the material layer and the sintering process, and reduce the yield and quality of sintering ores. After the sintering is carried out for a period of time, the positions of the sintered ore zone and the position near the combustion zone are heated by the heat accumulated on the upper part of the sinter bed, the injected gas in the area and the combustion of the solid fuel in the area, correspondingly, when the solid fuel and the gas are combustedAfter sintering, the temperature reduction rate in this region is smaller than that in the initial stage of sintering, and therefore this phenomenon is more pronounced in the middle and later stages of gas injection-assisted sintering than in the early stage of sintering. That is, the amount of solid carbon and CO used in the production of sintered ore is reduced due to the increase of the gas injection amount in the gas injection auxiliary sintering process ₂ The discharge amount, but also brings new technical problems.

In the prior art, the conventional sintering-assisted method using a gas injection technology, or the sintering-assisted method using injection after increasing the injection amount of gas and increasing the injection concentration, both adopt a method of continuously injecting (or injecting) gas to the sintering charge level. The invention provides a method for intermittently injecting and assisting sintering by decreasing gas flow, aiming at the problems in the prior art that the gas injection amount is increased, the injection concentration is increased and then the gas is continuously injected for assisting sintering. The method changes the original method of continuously injecting fuel gas in the process of injecting fuel gas, but uses the measure of decreasing fuel gas flow and intermittently injecting fuel gas into a material layer of a sintering mixture intermittently in time and gradually decreases in flow on the premise of maintaining the original fuel gas supplement amount. As shown in FIG. 6, in the present invention, gas injection Δ t ₁ Shortly after the duration, stop spraying delta t ₂ Duration, then continue to blow Δ t ₁ Duration, spray stop Δ t ₂ Its advantages are high curative effect, and no by-effect. Wherein blowing is Δ t ₁ Duration + spray cut Δ t ₂ The duration is one injection period, the process of injecting gas in the whole sintering process is repeated continuously, and the gas injection flow S corresponding to each injection period ₁ ，S ₂ ，S ₃ ……S _N (i.e. the gas injection flow rate corresponding to the ith injection period) is decreased in sequence. Blowing duration at each period ₁ Because of the injection of the fuel gas, the fuel gas is ignited and burnt at the position of the area near the burning zone and the sintering ore zone to release heat; the stop duration Deltat of each period ₂ In, because there is not the jetting of gas to mend, the area that originally takes place the gas burning then can take place to put out a fire because of the disappearance combustible gas, and this district can receive the cooling of air this moment. That is, the gas can be periodically injected and stoppedThe burning and flameout of the fuel gas are repeatedly generated near the position of the sintering ore zone close to the burning zone, so that the situation that the corresponding area is too high in temperature to cause a too thick red layer is avoided, and the technical problems that the material layer is poor in air permeability and sintering air draft negative pressure rises after the fuel gas injection amount is increased are effectively avoided.

In the process of gas injection auxiliary sintering, along with the progress of sintering, injected gas enters a sintering material layer to burn and release heat, and simultaneously solid fuel in the sintering material layer burns and releases a large amount of heat. It is worth noting that, after sintering carried out a period of time, even reduce solid fuel's ratio, the position near sintering ore deposit area and burning zone can receive sinter bed upper portion heat accumulation, this regional gas of jetting and this regional solid fuel's burning heating, it is corresponding, after solid fuel and gas burning, owing to still receive the heat accumulation of upper portion bed of material, therefore this regional cooling rate is less than in the sintering initial stage, thereby probably form thicker red layer, make the sintering middle and later stage more easily appear the relatively poor, the too big phenomenon of sintering convulsions negative pressure of bed of material gas permeability. That is to say, the problems of poor material layer air permeability and large air draft negative pressure caused by the over-thick red layer are more obvious in the middle and later period of the gas injection auxiliary sintering than in the early period of the sintering, or the phenomenon is more easily caused in the middle and later period of the sintering. Based on the method, the original method of continuously and uniformly injecting the fuel gas (namely, the fuel gas injection flow is unchanged) in the whole fuel gas injection auxiliary sintering process is changed into the method of periodically and intermittently injecting the fuel gas by decreasing the fuel gas injection flow. In the invention, the flow rate of the injected gas in each period is decreased progressively along with the increasing of the number of the injection periods, and the total amount of the injected gas in each period is decreased progressively because the duration of the injected gas in each period is the same, namely the heat released by the injected gas in the sintering material layer in each period is gradually reduced along with the increasing of the number of the periods. The sintering process is a typical air draft operation mode, and along with the progress of sintering, the heat storage effect from the upper part of a material layer in the middle and later stages of sintering is more obvious, and the quantity of gas required to be blown in the sintering process is less. Therefore, the invention adopts the measure of gas flow decreasing intermittent injection, and the sintering material layer is supplemented along with the progress of sinteringThe gas volume reduces gradually, and the sintering ore area can reduce with the heat that the burning zone is close to the region near by the gas heating of jetting can the step, and correspondingly, the cooling rate that corresponds the region can be more close with sintering earlier stage. Therefore, compared with the continuous and uniform injection in the prior art, the fuel gas flow decrement intermittent injection can realize the accurate control of the temperature of the combustion zone in each sintering period and the sintered ore zone area close to the combustion zone, and obtain a red layer with thinner thickness, thereby ensuring the proper bed air permeability and normal air draft negative pressure. The method of the invention is particularly used for remarkably improving the technical problems of gradual thickening of red layers in the middle and later sintering periods, worsening of the material layer air permeability, continuous rising of negative pressure of sintering air draft and the like, thereby allowing more fuel gas to be supplemented in the sintering process, and realizing solid fuel substitution and CO replacement with larger proportion and realizing ₂ Emission reduction is carried out to ensure the sintering effect and improve the yield and the quality of the sintering ore.

Furthermore, the invention determines a proper injection system by adjusting parameters of the injected gas (such as the cycle number of the injected gas, the injection time in the cycle, the injection stop time in the cycle, the gas injection flow in each cycle and the like), further realizes the accurate control of the final temperature in the cycle of the sinter bed in each time period on the premise of maintaining the original gas injection amount (namely the existing increased gas injection amount), improves the temperature change curve of the sinter bed and the area near the combustion zone in each time period, weakens the thickness of the red layer, ensures proper bed permeability and normal air draft negative pressure, and realizes the maximum gas injection amount under the condition of maintaining the bed permeability and the air draft negative pressure normal, thereby more obviously improving the solid fuel substitution amount, reducing the CO reduction ₂ And (5) discharging.

In the invention, the method for the gas flow decrement intermittent injection auxiliary sintering firstly determines the initial parameters of the injected gas, wherein the initial parameters of the injected gas comprise the cycle number N of the injected gas and the time length delta t of the injected gas in a single cycle ₁ Duration delta t of gas cut-off in a single cycle ₂ And initial gas injection flow rate S in each period _i (i.e., the amount of gas injected per unit time). After determining the initial parameters of the gas to be injected, i.e.And periodically and intermittently injecting gas to the charge level of the sintering mixture according to initial parameters, wherein the gas enters the sintering charge layer to burn for supplying heat and assisting in sintering. Then calculating the heat quantity Q released by the combustion of the injected fuel gas in the sintering material layer in the ith period _in，i The heat storage capacity of the upper material layer on the sinter bed at the position near the gas combustion and the delta t of air ₂ Cooling capacity Q of the sinter bed over time _co，i And judging the temperature change condition of the sinter bed at the position near the gas combustion in the ith period according to the heat balance principle, thereby realizing the control of the temperature of the sinter band and the combustion band area in the sinter bed. Wherein, the control to the sintering ore area in the sinter bed and the regional temperature of burning zone is realized according to the temperature change condition of sinter bed in the ith cycle, specifically includes: according to the heat balance principle, calculating the temperature change value delta T of the sintering material layer at the position near the gas combustion in the ith period _i Then calculating the actual final temperature T of the sinter bed at the corresponding position in the ith period _co，i Calculating the actual final temperature T of the sinter bed _co，i With a target temperature T _aim And comparing, and further adjusting the gas injection flow in the ith period, thereby realizing the control of the temperatures of the sintering ore zone and the combustion zone area in the sintering material layer and avoiding the conditions of overhigh temperature and over-thick red layer. In the present invention, the gas injection flow rate S in the i-th cycle _i Since the gas injection flow rate in the i-th cycle is adjusted by the adjustment formula, the values of the gas injection flow rate adjustment constants a and b may be set. In the present invention, the value range of a is generally-5 to-3, and the value range of b is generally 735 to 755. The number of cycles N of gas injection into the sinter mix in the sintering pallet is generally 6 to 16, for example N is 10. Duration delta t of gas injection in single period ₁ Typically 6 to 10s, e.g. Δ t ₁ Is 8s.

In the present invention, the target temperature T is _aim The combustion related to the type of the fuel gas, the concentration of the injected fuel gas and the flow rate of the injected fuel gas means that the combustion of the sintering ore zone and the combustion zone area in a single period can be realized according to the summary of laboratory research and practical experience of sintering engineeringTemperature threshold for gas extinction. The target temperature T _aim The range of values of (A) is 600-1000 ℃, preferably 700-850 ℃, more preferably 740-780 ℃. The value ranges of the target temperatures in each gas injection period are not greatly different, and generally, the target temperatures in the corresponding periods can be slightly increased along with the decreasing of the gas injection flow in each period. The invention determines a proper injection system by adjusting the gas injection flow in each period, namely the final temperature in the period in the controllable type (12), thereby accurately controlling the trend of the temperature curve near the sintering ore zone and the combustion zone in the sintering process, ensuring that the temperature reduction is too slow due to the continuous supplement of the gas after the high-temperature retention time in the sintering process is prolonged by the supplemented gas, further weakening the thickness of a red layer, and ensuring that the air permeability of a material layer and the air draft negative pressure are in the optimal state. In the invention, if the actual final temperature T of the sinter bed at the corresponding position in the ith period _co,i = target temperature T _aim The actual final temperature of the sinter bed is in the range of the target temperature, namely the temperature curve at the moment tends to be identical with the ideal sinter bed temperature curve, the gas at the corresponding position of the sinter bed is extinguished (namely the gas is extinguished at the corresponding position of the gas blowout stopping time interval) at the moment, the temperature of the sintering zone and the combustion zone area in the injection period is controlled in the normal range, the injection parameter at the moment is the appropriate injection parameter, and the system keeps the current injection parameter to continue to operate. If the actual final temperature T of the sinter bed at the corresponding position in the ith period _co,i > target temperature T _aim The temperature of the sintered ore zone and the combustion zone area in the injection period is higher, and at the moment, the gas at the position corresponding to the sinter bed possibly has the condition of not extinguishing (namely the gas at the position corresponding to the gas stop time interval is not extinguished), so that the conditions that the gas permeability of the sinter bed is influenced and the air draft negative pressure is increased due to the excessively thick red layer possibly occur; at the moment, the injection parameters need to be adjusted, namely, the values of the gas injection flow regulating constants a and b are adjusted, so that the gas injection flow in the ith period is reduced, and T is enabled to be _co，i ＝T _aim And further controlling the temperature of the sintering ore zone and the combustion zone to return to the normal range. If the corresponding position in the ith period is sinteredActual final temperature T of the bed _co，i <Target temperature T _aim At the moment, the gas at the corresponding position of the sinter bed is extinguished (namely, the gas at the corresponding position of the gas blowout stopping time interval is extinguished), but the temperatures of the sintering zone and the combustion zone region in the blowing period are lower, so that the normal operation of sintering and the quality of sintering ore can be influenced; at the moment, the injection parameters need to be adjusted, and the value of the gas injection flow regulating constants a and b is also adjusted, so that the gas injection flow in the ith period is increased, and T is enabled to be _co，i ＝T _aim And further controlling the temperature of the sintering ore zone and the combustion zone to return to the normal range.

In the process of adjusting the gas injection flow rate in the ith period, since the gas injection flow rate is adjusted according to the values of the gas injection flow rate adjustment constants a and b, in the process of adjusting the gas injection flow rate in the ith period, the gas injection flow rates in other injection periods need to be adjusted synchronously, and the temperatures of the sintering zone and the combustion zone region in other periods are ensured to be within a normal range.

In the invention, the total amount of fuel gas required to be injected into the sintering mixture in the sintering trolley

Wherein Q is _{Supplement device} The amount of the gas to be blown into the sintering material in the sintering pallet is determined by the kind of the sintering material, the average particle size of the sintering material, the proportion of the solid fuel in the sintering material, the kind of the gas, and the like. In the present invention, the cooling rate q of the sinter bed in the i-th cycle by air cooling _co，i ＝h _co ·(T _{Combustion of i} -T _∞ ) ξ · m · a, the cooling rate of the sinter bed by air cooling and the sinter bed cooling coefficient, the combustion temperature of the gas, the ambient air temperature, the internal surface area of the sinter bed, and the proportion of the combustion zone in the height direction to the height of the entire sinter bedAnd so on. In addition, in the present application, the specific values of the parameters involved in formulas (1) - (12) can be obtained by detection, calculation or according to production experience.

It should be noted that the number of cycles of gas injection and the total amount of gas to be injected into the sinter mix in the sintering pallet are based on the sinter mix in the region corresponding to the gas injection zone. The cycle number of the injected gas refers to the number of times of injection and stop of injection when the sintering mixture passes through the gas injection section. The total amount of gas to be injected into the sintering mixture in the sintering trolley is based on the realization of the maximum gas injection amount, so that the solid fuel substitution amount is increased, and the CO is reduced ₂ On the premise of emission, the amount of gas required to be injected by the sintering mixture is increased.

In addition, since the red layer means a region with the temperature in the sintering material layer being above about 1000 ℃, and the region with the temperature above 1000 ℃ in the sintering material layer is mainly concentrated in the combustion zone and a partial region of the sintering ore zone close to the combustion zone, the red layer thickness is controlled by controlling the temperature of the sintering ore zone and the combustion zone region in the sintering material layer, and the temperature of the upper region of the combustion zone and the temperature of the sintering ore zone close to the combustion zone are controlled within a reasonable range mainly in the thickness direction of the material layer.

In the present application, the terms "gas combustion position", "position near gas combustion", and "corresponding position" have the same meaning.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the invention changes the existing method for continuously and uniformly injecting the gas, skillfully controls the injection and the stop of the gas through the gradual decrease and the intermittent injection of the gas flow, further ensures that the gas is repeatedly ignited and extinguished near a combustion zone, and leaves a certain cooling time for the sintering finished ore in a specific area while supplementing heat through the gas feeding layer, thereby being capable of controlling the temperature of the combustion zone and the sintering ore zone not to be too high.

2. The invention selects the cycle number of the injected fuel gas, the fuel gas injection time length and the injection stopping time length in a single cycle, and adjusts the fuel gas injection flow rate in each cycle to determine a proper injection system, so that the final temperature in the cycle of the sinter bed can be controlled, the trend of the temperature curve near the sinter ore zone and the combustion zone in the sintering process is accurately controlled, the temperature maintaining time in the sintering process is ensured not to be too slow due to the continuous injection of the fuel gas after being prolonged by the supplemented fuel gas, the thickness of the red layer is further weakened, and the air permeability of the sinter bed and the air draft negative pressure are ensured to be in the optimal state.

3. The fuel gas flow decreasing intermittent injection method can realize accurate control of the temperature of a combustion zone at each sintering period and a sintering ore zone area close to the combustion zone, ensure that the red layer thickness is not too high and the bed permeability is proper, and particularly obviously improve the technical problems of gradual thickening of the red layer at the middle and later sintering periods, worsening of the bed permeability, continuous rising of sintering exhaust negative pressure and the like, thereby allowing more fuel gas to be supplemented in the sintering process, and realizing solid fuel substitution and CO substitution with larger proportion and realizing ₂ And (5) emission reduction.

Drawings

FIG. 1 is a schematic diagram of a method for sintering by intermittently injecting gas at a decreasing gas flow rate;

FIG. 2 is a flow chart of a method for sintering by intermittent injection with decreasing gas flow rate according to the present invention;

FIG. 3 is a bed distribution diagram of a sinter mix;

FIG. 4 is a graph showing the temperature of the sinter bed in the case of gas injection and in the case of no gas injection;

FIG. 5 is a graph showing the temperature of a sinter bed in two cases of increasing the gas injection concentration and adopting the conventional gas injection;

FIG. 6 is a schematic view showing that the gas is intermittently injected periodically and the injection flow rate of the gas is decreased in each period according to the present invention;

FIG. 7 is a graph showing the temperature of the sinter bed in the case of both the intermittent injection of gas with decreasing injection flow rate and the conventional continuous injection of gas.

Reference numerals are as follows:

1: sintering the trolley; a1: sintering the ore belt; a2: a combustion zone; a3: drying the preheating zone; a4: an overwetting belt; a5: the raw material tape.

Detailed Description

Along the thickness direction of the sinter bed, the sinter bed on the sintering trolley mainly comprises a sinter ore belt, a combustion belt, a drying preheating belt, an over-wetting belt and an original material belt from top to bottom in sequence.

In the invention, the time length of injecting fuel gas in a single period is set to be delta t ₁ Therefore, the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley. And N is the period number of gas injection for the sintering mixture in the sintering trolley. S _i The flow rate of the gas injection in the ith period is obtained.

In the present invention, the ithGas injection flow rate S in cycle _i Comprises the following steps:

S _i ＝a·i+b…………(2)。

in the formula: a. and b is a gas injection flow regulating constant.

1) And determining the number of cycles for injecting the gas, the time length for injecting the gas in a single cycle and the time length for stopping injecting the gas in the single cycle.

3) And in the gas injection time of the ith period, calculating the heat released by the injected gas in the sintering material layer, and calculating the heat storage amount of the sintering material layer at the gas combustion position.

In the present invention, step 1) comprises the following substeps:

1a) Calculating the operation time t of the sintering trolley in the gas injection section according to the length L of the gas injection section on the sintering machine and the operation speed v of the sintering trolley, namely the total time t for injecting gas to the sintering mixture in the sintering trolley is as follows:

1b) Setting the number of cycles for injecting gas into the sintering mixture in the sintering trolley as N and the time length of injecting gas in a single cycle as delta t ₁ Thereby, singlyTime length delta t of gas injection stopping in period ₂ Comprises the following steps:

in the formula: g is the total amount of gas required to be blown by the sintering mixture in the sintering trolley. And m is the quality of the sintering mixture in the corresponding area of the gas injection section. Q _{Supplement device} The heat quantity needs to be supplemented for the sintering mixture of unit mass after the solid fuel proportion is reduced integrally. H is the heat value of the fuel gas.

Preferably, the determining the initial gas injection flow rate in each period specifically includes: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow rate adjustment constants a, b are set ₀ 、b ₀ And satisfy

Obtaining the following components:

initial gas injection flow S in the 1 st cycle ₁ ＝a ₀ +b ₀ 。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ 。

……

Initial gas injection flow S in the ith period _i ＝a ₀ ×i+b ₀ 。

……

Initial gas injection flow S in Nth period _N ＝a ₀ ×N+b ₀ 。

In the invention, in step 3), the heat storage amount of the sinter bed on the upper bed at the corresponding position in the gas injection time of the ith period is calculated, and specifically:

in the formula: q _x，i The sintering material layer is subjected to the heat storage quantity of the upper material layer at the combustion position of the gas in the ith period.

Q _co，i ＝q _co，i ×Δt ₂ ............(9)。

In the formula: q _co，i The cooling amount of the air to the sinter bed in the ith period is shown. h is _co Is the sinter bed cooling coefficient, h _co The value range of (a) is 50-60W/(m) ² ·℃)。T _{Combustion of i} The combustion temperature of the fuel gas in the sintering material layer. T is a unit of _∞ Is the air temperature. And m is the mass of the sintering mixture in the corresponding area of the gas injection section. A is the specific surface area of the combustion zone in the sintering material layer. Xi is the proportion of the height of the combustion zone in the height direction of the whole sintering material layer, and the value range of xi is 0-1, preferably 0.01-0.1.

In the present invention, step 5) comprises the following substeps:

c _p .ξ·m.ΔT _i ＝Q _in，i +Q _x，i -Q _co，i ............(10)。

Namely have

In the formula: c. C _p Is the average specific heat capacity of the sinter bed. Q _x，i The sintering material layer is subjected to the heat storage amount of the upper material layer at the gas combustion position of the ith period.

5b) Calculating the actual final temperature T of the sinter bed at the corresponding position in the ith period _co，i ：

T _co，i ＝T _{Combustion of i} +ΔT _i ............(12)。

5c) Comparing the actual final temperature T of the sinter bed in the ith period _co，i With a target temperature T _aim And adjusting the gas injection flow adjusting constants a and b, and further adjusting the gas injection flow in the ith period, thereby realizing the control of the temperature of the sintering ore zone and the combustion zone area in the sintering material layer.

In the present invention, the substep 5 c) is specifically:

if the actual final temperature T of the sinter bed in the ith period _co，i = target temperature T _aim And controlling the temperature of the sintering zone and the combustion zone within a normal range in the period, and keeping the current injection parameters of the system to continuously operate.

If the actual final temperature T of the sinter bed in the ith period _co，i > target temperature T _aim At the moment, the gas injection flow rate adjusting constants a and b are adjusted, so that the gas injection flow rate in the ith period is reduced, and T is enabled _co，i ＝T _aim 。

If the actual final temperature T of the sinter bed in the ith period _co，i < objectTemperature T _aim At the moment, the gas injection flow rate adjusting constants a and b are adjusted, so that the gas injection flow rate in the ith period is increased, and T is enabled _co，i ＝T _aim 。

Example 1

As shown in figure 1, the method for auxiliary sintering by intermittent injection with gradually decreased gas flow comprises the steps of periodically and intermittently injecting gas to the charge level of a sintering mixture, gradually decreasing the injected gas flow in each period along with the increasing of the injection period number, and enabling the gas to enter a sintering charge layer for combustion and heat supply. In the process of gas injection, the temperature of the sintered ore zone A1 and the combustion zone A2 in the sinter bed is controlled by adjusting the gas injection flow in each period.

As shown in fig. 3, the sinter bed on the sintering pallet 1 mainly includes, in order from top to bottom, a sinter bed A1, a combustion zone A2, a drying and preheating zone A3, an over-wetting zone A4, and an original material zone A5 along the thickness direction of the sinter bed.

Example 2

The intermittent jetting gas is periodically and intermittently jetted to the material surface of the sintered mixture, the jetted gas flow is decreased gradually in each period along with the increasing of the jetting period number, and the gas enters the sintered material layer to burn and supply heat. In the process of gas injection, the temperature of the sintered ore zone A1 and the combustion zone A2 in the sinter bed is controlled by adjusting the gas injection flow in each period.

Setting the cycle number of gas injection for the sintering mixture in the sintering trolley as N. In the process of gas injection, the period of gas injection is sequentially 1 st period, 2 nd period \8230 \ 8230and Nth period, and the gas flow rate correspondingly injected in each period is sequentially S ₁ ，S ₂ ……S _N . Wherein S is ₁ ＞S ₂ ＞……＞S _N 。

Example 3

Example 2 was repeated except that the gas injection time period in a single cycle was set to Δ t ₁ Therefore, the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley. And N is the cycle number of gas injection for the sintering mixture in the sintering trolley. S _i The gas injection flow in the ith period is shown.

Example 4

Example 3 was repeated except that the gas injection flow rate S in the i-th cycle _i Comprises the following steps:

S _i ＝a·i+b…………(2)。

in the formula: a. and b is a gas injection flow regulating constant.

Example 5

The method for controlling the temperature of the sintering ore zone A1 and the combustion zone A2 in the sintering material layer specifically comprises the following steps:

Example 6

As shown in fig. 2, the implementation of controlling the temperature of the sintering ore zone A1 and the combustion zone A2 in the sinter layer specifically includes the following steps:

Step 1) comprises the following substeps:

1b) Setting the number of cycles for injecting gas into the sintering mixture in the sintering trolley as N and the time length of injecting gas in a single cycle as delta t ₁ Whereby, during a single cycle, gas injection is stoppedLong at ₂ Comprises the following steps:

In the step 2), the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley. And m is the quality of the sintering mixture in the corresponding area of the gas injection section. Q _{Supplement device} The heat quantity needs to be supplemented for the sintering mixture of unit mass after the solid fuel proportion is reduced integrally. H is the heat value of the fuel gas.

The method for determining the initial gas injection flow in each period specifically comprises the following steps: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow adjustment constants a and b are set ₀ 、b ₀ And satisfy

Obtaining the following components:

initial gas injection flow S in the 1 st cycle ₁ ＝a ₀ +b ₀ 。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ 。

……

Initial gas injection flow S in the ith period _i ＝a ₀ ×i+b ₀ 。

……

Initial gas injection flow S in Nth period _N ＝a ₀ ×N+b ₀ 。

In step 3), in the gas injection time of the ith period, calculating the heat released by the injected gas in the sintering bed by combustion, specifically:

In step 3), calculating the heat storage capacity of the upper batch layer on the sinter bed at the corresponding position in the ith period specifically includes:

4) In the gas blowout stopping time of the ith period, calculating the cooling capacity of air to the sinter bed, specifically: gas blowout stopping time delta t in ith period ₂ The cooling rate of the sinter bed by air cooling is q _co，i Namely, the following steps are provided:

Q _co，i ＝q _co，i ×Δt ₂ ............(9)。

In the formula: q _co，i The cooling amount of the air to the sinter bed in the ith period is shown. h is _co Is the sinter bed cooling coefficient, h _co Is 55W/(m) ² ·℃)。T _{Combustion of i} For the combustion temperature of the combustion gases in the sinter bed, from T _{Combustion of i} ＝1005+32.5ln(e ⁱ +i ² + 503.2) determination。T _∞ Is the air temperature. And m is the mass of the sintering mixture in the corresponding area of the gas injection section. A is the specific surface area of the combustion zone in the sintering material layer. Xi is the proportion of the combustion zone in the height direction to the height of the whole sinter bed, and the value of xi is 0.06.

Step 5) comprises the following substeps:

cp.ξ·m.ΔT _i ＝Q _in，i +Q _x，i -Q _co，i .............(10)。

Namely have

T _co，i ＝T _{Combustion of i} +ΔT _i ............(12)。

Example 7

Example 6 is repeated, except that in substep 5 c), the target temperature T _aim The range of (A) is 740 to 780 ℃.

The substep 5 c) is specifically:

If the actual final temperature T of the sinter bed in the ith period _co，i >Target temperature T _aim Adjusting the gas injection flow rate adjusting constants a and b, and further reducing the gas injection flow rate in the ith period to ensure that T is equal to _co，i ＝T _aim 。

Application example 1

The intermittent blowing auxiliary sintering method with gradually decreased gas flow includes intermittent blowing gas to the material surface of the mixture to be sintered, gradually decreasing the gas flow rate in each period with the increasing of the blowing period number, and burning the gas in the material layer to heat. In the process of gas injection, the temperature of the sintered ore zone A1 and the combustion zone A2 in the sinter bed is controlled by adjusting the gas injection flow in each period.

The method for controlling the temperature of the sintered ore zone A1 and the combustion zone A2 in the sinter bed specifically comprises the following steps:

Step 1) comprises the following substeps:

1a) Calculating the operation time t of the sintering pallet in the gas injection section according to the length L =8.77m of the gas injection section on the sintering machine and the operation speed v =2m/min of the sintering pallet, namely the total time t for injecting gas into the sintering mixture in the sintering pallet is as follows:

1b) Setting the number of cycles N =10 for injecting gas into the sinter mix in the sintering pallet, and the time length Deltat for injecting gas in a single cycle ₁ =8s, whereby the duration Δ t of the gas injection stoppage in a single cycle ₂ Comprises the following steps:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley. m is the mass of the sintering mixture in the corresponding area of the gas injection section, and m =172800kg. Q _{Supplement device} The heat quantity, Q, is required to be supplemented for integrally reducing the sintered mixture of unit mass after the solid fuel is proportioned _{Supplement device} =12000kJ/kg. H is the heat value of the fuel gas, and H =35588kJ/m ³ 。

The method for determining the initial gas injection flow in each period specifically comprises the following steps: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow rate adjustment constants a, b are set ₀ ＝-4、b ₀ =750.325, and satisfies

Thus obtaining the following components:

initial gas injection flow S in 1 st cycle ₁ ＝a ₀ +b ₀ ＝746.325m ³ /s。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ ＝742.325m ³ /s。

……

Initial gas injection flow S in 10 th cycle _N ＝a ₀ ×10+b ₀ ＝710.325m ³ /s。

3) And calculating the heat released by combustion of the injected fuel gas in the sintering material layer in the fuel gas injection time of the ith period, wherein i =2, namely:

Q _in，2 ＝S ₂ ·Δt ₁ ·H＝211342896.8kJ............(6)。

in the formula: q _in，2 The heat released by the combustion of the injected gas in the 2 nd period.

Correspondingly, in step 3), in the 2 nd period of gas injection time, the heat storage capacity of the upper material layer on the sinter bed at the corresponding position is calculated, specifically:

Q _x，2 ＝10.72×2 ⁹ -545×2 ⁸ +11916.97×2 ⁷ -146417.39×2 ⁶ +1105050×2 ⁵ -5257230×2 ⁴ +15612800×2 ³ -27524500×2 ² +26912800×2-10713900＝1182647.84kJ............(7)。

in the formula: q _x，2 The sintered material layer is subjected to the heat storage amount of the upper material layer at the gas combustion position in the 2 nd period.

4) In the gas blowout stopping time of the 2 nd period, the cooling capacity of the air to the sinter bed is calculated, and the method specifically comprises the following steps: gas stop time delta t in the 2 nd period ₂ The cooling rate of the sinter bed by air cooling is q _co，2 Namely, the following steps are provided:

q _co，2 ＝h _co ·(T _{combustion, 2} -T _∞ )·ξ·m·A............(8)。

Q _co，2 ＝q _co，2 ×Δt ₂ ＝h _co ·(T _{Combustion, 2} -T _∞ )·ξ·m·A·Δt ₂ ＝50×[1005+32.5ln(e ² +2 ² +503.2)-30]×0.05×172800×0.02326×18.31＝216717368.58kJ............(9)。

In the formula: q _co，2 The cooling amount of the air to the sinter bed in the 2 nd period. h is _co Is the sinter bed cooling coefficient, h _co ＝50W/(m ² ·℃)。T _{Combustion, 2} The combustion temperature T of the combustion gas in the sintering material layer in the 2 nd period _{Combustion, 2} ＝[1005+32.5ln(e ² +2 ² +503.2)]℃。T _∞ Is the air temperature, T _∞ =30 ℃. m is the mass of the sintering mixture in the corresponding area of the gas injection section, and m =172800kg. A is the specific surface area of a combustion zone in a sintering material layer, and A =0.02326m ² (ii) in terms of/g. Xi is the proportion of the height of the combustion zone in the height direction in the whole sinter layer, and xi =0.05.

5) And judging the temperature change condition of the sinter bed in the 2 nd period according to the heat released by the combustion of the injected gas, the heat storage capacity of the sinter bed on the position where the sinter bed is combusted by the gas and the cooling capacity of air to the sinter bed, and further realizing the control of the temperature of the sinter band and the combustion band area in the sinter bed.

Step 5) comprises the following substeps:

5a) According to the heat balance principle, calculating the temperature change value delta T of the sinter bed at the gas combustion position in the 2 nd period ₂ ：

c _p .ξ·m.ΔT ₂ ＝Q _in，2 +Q _x，2 -Q _co，2 ..........(10)。

Namely have

In the formula: c. C _p Is the average specific heat capacity of the sinter bed, c _p ＝1.1kJ/(kg·℃)。

5b) Calculating the actual final temperature T of the sinter bed at the corresponding position in the 2 nd period _co，2 ：

T _co，2 ＝T _{Combustion, 2} +ΔT ₂ ＝1005+32.5ln(e ² +2 ² +503.2)-441＝767℃............(12)；

5c) Comparative 2 nd cycle burnActual final temperature T of the binder layer _co，2 With a target temperature T _aim And adjusting the gas injection flow adjusting constants a and b, and further adjusting the gas injection flow in the 2 nd period, thereby realizing the control of the temperature of the sintering ore zone and the combustion zone area in the sintering material layer.

Due to the target temperature T _aim In the range of 740 to 780 ℃, i.e. the actual final temperature T of the sinter bed in the 2 nd cycle _co，2 At a target temperature T _aim The temperature of the sintering ore zone A1 and the combustion zone A2 is controlled in a normal range in the period, and the system keeps the current injection parameters to continue to operate.

Application example 2

Step 1) comprises the following substeps:

1b) Setting the number of cycles N =10 for gas injection into the sinter mix in the sintering pallet, andduration delta t of gas injection in each period ₁ =8s, whereby the duration Δ t of gas injection stoppage in a single cycle ₂ Comprises the following steps:

In step 2), the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

The method for determining the initial gas injection flow in each period specifically comprises the following steps: setting initial values a of gas injection flow rate adjustment constants a and b according to the gas injection flow rate Si = a · i + b in the ith period ₀ ＝-3、b ₀ =744.825 and satisfy

Obtaining the following components:

initial gas injection flow S in the 1 st cycle ₁ ＝a ₀ +b ₀ ＝741.825m ³ /s。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ ＝738.825m ³ /s。

……

Initial gas injection flow S in 10 th cycle _N ＝a ₀ ×10+b ₀ ＝714.825m ³ /s。

Q _in，2 ＝S ₂ ·Δt ₁ ·H＝210346432.8kJ............(6)。

4) In the gas blowout stopping time of the 2 nd period, the cooling capacity of the air to the sinter bed is calculated, and the method specifically comprises the following steps: gas blowout stop time delta t in 2 nd period ₂ The cooling rate of the sinter bed by air cooling is q _co，2 Namely, the following steps are provided:

q _co，2 ＝h _co ·(T _{combustion, 2} -T _∞ )·ξ·m·A............(8)。

In the formula: q _co，2 The cooling quantity of the air to the sinter bed in the 2 nd period is shown. h is _co Is the sinter bed cooling coefficient, h _co ＝50W/(m ² ·℃)。T _{Combustion, 2} For combustion of gas in the sinter bed in the 2 nd cycleTemperature, T _{Combustion, 2} ＝[1005+32.5ln(e ² +2 ² +503.2)]℃。T _∞ Is the air temperature, T _∞ =30 ℃. m is the mass of the sintering mixture in the corresponding area of the gas injection section, and m =172800kg. A is the specific surface area of a combustion zone in a sintering material layer, and A =0.02326m ² (iv) g. Xi is the proportion of the height of the combustion zone in the height direction in the whole sinter layer, and xi =0.05.

Step 5) comprises the following substeps:

c _p .ξ·m.ΔT ₂ ＝Q _in，2 +Q _x，2 -Q _co，2 ............(10)。

Namely have

T _co，2 ＝T _{Combustion, 2} +ΔT ₂ ＝1005+32.51n(e ² +2 ² +503.2)-546＝662℃............(12)；

5c) Comparing the actual final temperature T of the sinter bed in the 2 nd cycle _co，2 With a target temperature T _aim And adjusting the gas injection flow adjusting constants a and b, and further adjusting the gas injection flow in the 2 nd period, thereby realizing the control of the temperature of the sintering ore zone and the combustion zone area in the sintering material layer.

Due to the fact thatTarget temperature T _aim The value range of (a) is 740 to 780 ℃, and obviously the actual final temperature T of the sinter bed in the 2 nd period _co，2 <Target temperature T _aim Explaining that the temperature of the sintering zone A1 and the combustion zone A2 is lower in the period and can influence the normal operation of sintering and the quality of the sintering ore, the sizes of gas injection flow constants a and b are adjusted at the moment, and then the gas injection flow in the 2 nd period is increased, so that T is enabled to be equal _co，2 ＝T _aim And further controlling the temperature of the sintering zone and the combustion zone in the 2 nd period to return to the normal range, and simultaneously ensuring that the temperature of the sintering zone and the combustion zone in other periods is also in the normal range.

Application example 3

Step 1) comprises the following substeps:

1b) Setting a period for blowing gas to the sinter mix in the sintering palletNumber N =10, and duration Δ t of gas injection in a single cycle ₁ =8s, whereby the duration Δ t of the gas injection stoppage in a single cycle ₂ Comprises the following steps:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley. m is the mass of the sintering mixture in the corresponding area of the gas injection section, and m =172800kg. Q _{Supplement device} The heat quantity, Q, of the sintered mixture of unit mass needs to be supplemented after the solid fuel proportion is reduced integrally _{Supplement device} =12000kJ/kg. H is the heat value of the fuel gas, and H =35588kJ/m ³ 。

The method for determining the initial gas injection flow in each period specifically comprises the following steps: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow adjustment constants a and b are set ₀ ＝-4、b ₀ =753.825, and satisfy

Thus obtaining the following components:

initial gas injection flow S in 1 st cycle ₁ ＝a ₀ +b ₀ ＝749.825m ³ /s。

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ ＝745.825m ³ /s。

……

Initial gas injection flow S in 10 th cycle _N ＝a ₀ ×10+b ₀ ＝713.825m ³ /s。

Q _in，2 ＝S ₂ ·Δt ₁ ·H＝212339360.8kJ............(6)。

q _co，2 ＝h _co ·(T _{combustion, 2} -T _∞ )·ξ·m·A............(8)。

Q _co，2 ＝q _co，2 ×Δt ₂ ＝h _co ·(T _{Combustion, 2} -T _∞ )·ξ·m·A·Δt ₂ ＝50×[1005+32.51n(e ² +2 ² +503.2)-30]×0.05×172800×0.02326×18.31＝216717368.58kJ............(9)。

In the formula: q _co，2 The cooling amount of the air to the sinter bed in the 2 nd period. h is a total of _co Is the sinter bed cooling coefficient, h _co ＝50W/(m ² ·℃)。T _{Combustion, 2} For combustion in cycle 2Combustion temperature of gas in the sinter bed, T _{Combustion, 2} ＝[1005+32.5ln(e ² +2 ² +503.2)]℃。T _∞ Is the air temperature, T _∞ =30 ℃. m is the mass of the sintering mixture in the corresponding area of the gas injection section, and m =172800kg. A is the specific surface area of a combustion zone in a sintering material layer, and A =0.02326m ² (ii) in terms of/g. Xi is the proportion of the height of the combustion zone in the height direction in the whole sinter layer, and xi =0.05.

Step 5) comprises the following substeps:

c _p .ξ·m.ΔT ₂ ＝Q _in，2 +Q _x，2 -Q _co，2 ............(10)。

Namely have

T _co，2 ＝T _{Combustion, 2} +ΔT ₂ ＝1005+32.5ln(e ² +2 ² +503.2)-546＝872℃............(12)；

Due to the target temperature T _aim The value range of (1) is 740-780 ℃, obviously the actual final temperature T of the sinter bed in the 2 nd period _co，2 >Target temperature T _aim Explaining that the temperature of the sintering ore zone A1 and the combustion zone A2 is higher in the period, the red layer is too thick, the air permeability of the material layer is affected, and the condition of negative pressure rise of air draft is possibly caused, at the moment, the sizes of the gas injection flow constants a and b are adjusted, and further the gas injection flow in the 2 nd period is reduced, so that T is enabled to be T _co，2 ＝T _aim And further controlling the temperature of the sintering zone and the combustion zone in the 2 nd period to return to the normal range, and simultaneously ensuring that the temperature of the sintering zone and the combustion zone in other periods is also in the normal range.

Comparative example 1

The method is characterized in that gas is continuously and uniformly injected to the charge level of a sintering mixture, and the gas enters a sintering charge layer to be combusted for heat supply to assist sintering. Wherein, aiming at the sintering mixture in the corresponding area of the gas injection section, the total amount G of the gas continuously injected ₁ ＝58266m ³ Here, total amount of gas G continuously injected ₁ The total amount G of the intermittently injected gas is equal to the gas flow rate decreasing in application example 1. Calculating the total time length t of gas injection to the sintering mixture in the sintering pallet according to the length L =8.77m of the gas injection section on the sintering machine and the running speed v =2m/min of the sintering pallet ₁ = L/v =263.1s, where the total time t for the gas injection into the sinter mix in the sinter car is ₁ The total time t (including the injection time period and the spray stopping time period) for injecting the fuel gas into the sintering mixture in the sintering pallet in the application example 1 is equal. In comparative example 1, the gas was uniformly injected at all times, that is, the gas injection flow rate (that is, the injection amount of the gas per unit time) was constant, wherein the gas injection flow rate S was ₁ ＝G ₁ /t ₁ ＝221.46m ³ /s。

The temperature of the sinter layer during sintering was measured, and the temperature change curves of the sinter layer of application example 1 and comparative example 1 were plotted, as shown in fig. 7. The relevant test data for application example 1 and comparative example 1 are recorded as follows:

the invention changes the existing method for continuously and uniformly injecting fuel gas, and adopts the measure of fuel gas flow decreasing and intermittent injection to inject the fuel gas into the sintering material layer. As can be seen from the above table in conjunction with FIG. 7, the present invention can achieve the maximum gas injection amount to ensure a large proportion of solid fuel substitution and CO substitution while maintaining the original gas supply amount ₂ On the premise of emission reduction, the temperature change curve of the sintered ore zone and the area near the combustion zone is improved. The invention can realize the accurate control of the temperature of the burning zone in each sintering period and the sinter zone area close to the burning zone, further weaken the thickness of the red layer, ensure the proper material layer air permeability and normal air draft negative pressure, and particularly obviously improve the related technical problems in the middle and later sintering periods, thereby ensuring the sintering effect and improving the yield and the quality of the sinter.

Claims

1. A method for auxiliary sintering by intermittent injection with decreasing gas flow is characterized in that: the method comprises the following steps of (1) periodically and intermittently injecting gas to the charge level of a sintering mixture, wherein the flow of the injected gas in each period is reduced gradually along with the increasing of the number of injection periods, and the gas enters a sintering charge layer to be combusted and supplied with heat; and in the process of gas injection, the temperature of the sintering ore zone and the combustion zone area in the sintering material layer is controlled by adjusting the gas injection flow in each period.

2. The method of claim 1, wherein: setting the cycle number of gas injection for the sintering mixture in the sintering trolley as N; in the process of gas injection, the period of gas injection is sequentially 1 st period, 2 nd period \8230 \ 8230and Nth period, and the gas flow rate correspondingly injected in each period is sequentially S ₁ ，S ₂ ……S _N (ii) a Wherein S is ₁ ＞S ₂ ＞……＞S _N 。

3. The method of claim 2, wherein: setting the time length of gas injection in a single period as delta t ₁ Therefore, the total amount of the gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is the total amount of gas to be blown by the sintering mixture in the sintering trolley; n is the cycle number of gas for blowing the sintering mixture in the sintering trolley; s. the _i The gas injection flow in the ith period is shown.

4. The method of claim 3, wherein: gas injection flow S in the ith period _i Comprises the following steps:

S _i ＝a·i+b…………(2)；

in the formula: a. and b is a gas injection flow regulating constant.

5. The method according to any one of claims 1-4, wherein: the method for controlling the temperatures of the sintering ore zone and the combustion zone in the sintering material layer specifically comprises the following steps:

1) Determining the cycle number of gas injection, the time length of gas injection in a single cycle and the time length of gas injection stopping in a single cycle;

2) Determining the initial gas injection flow in each period according to the total amount of gas to be injected by the sintering mixture in the sintering trolley;

3) In the gas injection time of the ith period, calculating the heat released by the injected gas in the sintering material layer, and calculating the heat storage capacity of the sintering material layer on the sintering material layer at the gas combustion position;

4) Calculating the cooling capacity of the air to the sinter bed in the gas spraying stopping time of the ith period;

5) And judging the temperature change condition of the sinter bed in the ith period according to the heat released by the combustion of the injected gas, the heat storage amount of the sinter bed at the position where the sinter bed is combusted by the gas and the cooling amount of air to the sinter bed, and further realizing the control of the temperature of a sinter band and a combustion band area in the sinter bed.

6. The method of claim 5, wherein: step 1) comprises the following substeps:

1b) Setting the number of cycles for injecting gas into the sintering mixture in the sintering trolley as N and the time length of injecting gas in a single cycle as delta t ₁ Whereby the duration of gas injection cut off in a single cycle is Δ t ₂ Comprises the following steps:

7. the method according to claim 5 or 6, characterized in that: in the step 2), the total amount of gas to be injected into the sintering mixture in the sintering trolley is as follows:

in the formula: g is the total amount of gas to be injected into the sintering mixture in the sintering trolley; m is the mass of the sintering mixture in the corresponding area of the gas injection section; q _{Supplement device} Heat is required to be supplemented for integrally reducing the sintering mixture of unit mass after the solid fuel is proportioned; h is the heat value of the fuel gas;

it is preferable thatDetermining the initial gas injection flow in each period specifically comprises the following steps: according to the gas injection flow S in the ith period _i = a · i + b, initial values a of gas injection flow rate adjustment constants a, b are set ₀ 、b ₀ And satisfy

Obtaining the following components:

initial gas injection flow S in the 1 st cycle ₁ ＝a ₀ +b ₀ ；

Initial gas injection flow S in the 2 nd period ₂ ＝a ₀ ×2+b ₀ ；

……

Initial gas injection flow S in the ith period _i ＝a ₀ ×i+b ₀ ；

……

Initial gas injection flow S in Nth period _N ＝a ₀ ×N+b ₀ 。

8. The method of claim 7, wherein: in step 3), in the gas injection time of the ith period, calculating the heat released by the injected gas in the sintering bed by combustion, specifically:

Q _in，i ＝S _i ·Δt ₁ ·H＝(a ₀ ·i+b ₀ )·Δt ₁ ·H............(6)；

in the formula: q _in，i The heat released by the combustion of the injected gas in the ith period; and/or

Q _x，i ＝10.72i ⁹ -545i ⁸ +11916.97i ⁷ -146417.39i ⁶ +1105050i ⁵ -5257230i ⁴ +15612800i ³ -27524500i ² +26912800i-10713900............(7)；

in the formula: q _x，i For combustion position of gas in i-th cycleThe sinter bed receives the heat storage capacity of the upper bed.

9. The method according to any one of claims 6-8, wherein: in step 4), the cooling amount of the air to the sinter bed is calculated within the gas blowout stop time of the ith period, specifically: gas blowout stopping time delta t in ith period ₂ The cooling rate of the sinter bed by air cooling is q _co，i Namely, the following steps are provided:

Q _co，i ＝q _co，i ×Δt ₂ ............(9)；

in the formula: q _co，i The cooling quantity of the air to the sinter bed in the ith period is calculated; h is _co Is the sinter bed cooling coefficient, h _co The value range of (A) is 50-60W/(m) ² ·℃)；T _{Combustion of i} The combustion temperature of the fuel gas in the sintering material layer; t is _∞ Is the air temperature; m is the quality of the sintering mixture in the corresponding area of the gas injection section; a is the specific surface area of a combustion zone in the sintering material layer; xi is the proportion of the combustion zone in the height direction to the height of the whole sinter bed, and the value range of xi is 0-1, preferably 0.01-0.1.

10. The method of claim 9, wherein: step 5) comprises the following substeps:

c _p .ξ·m.ΔT _i ＝Q _in，i +Q _x，i -Q _co，i ............(10)；

Namely have

In the formula: c. C _p Being a sinter bedAn average specific heat capacity; q _x，i The sintering material layer is subjected to the heat storage quantity of the upper material layer at the ith period gas combustion position;

T _co，i ＝T _{Combustion of i} +ΔT _i ............(12)；

11. The method of claim 10, wherein: substep 5 c) is specifically:

if the actual final temperature T of the sinter bed in the ith period _co，i = target temperature T _aim The temperature of the sintering zone and the combustion zone is controlled within a normal range in the period, and the system keeps the current injection parameters to continue to operate;

if the actual final temperature T of the sinter bed in the ith period _co，i >Target temperature T _aim At the moment, the gas injection flow rate adjusting constants a and b are adjusted, so that the gas injection flow rate in the ith period is reduced, and T is enabled _co，i ＝T _aim ；

If the actual final temperature T of the sinter bed in the ith period _co，i <Target temperature T _aim Adjusting the gas injection flow rate adjusting constants a and b, and increasing the gas injection flow rate in the ith period to ensure that T is equal to _co，i ＝T _aim ；