Sintering process oxygen-enriched combustion air-fuel ratio optimization method

Abstract

The present application relates to the field of blast furnace metallurgy, and more particularly to a sintering process oxygen-enriched combustion air-fuel ratio optimization method, comprising the following steps: step one, controlling the oxygen content of the mixed combustion-supporting air by PID control, setting the oxygen content so that the mixed combustion-supporting air becomes a stable mixed combustion-supporting air with high oxygen content; step two, triggering air-fuel ratio optimization according to the field situation; step three, keeping the coal gas opening unchanged, increasing or decreasing the mixed combustion-supporting air volume, and if the ignition temperature is higher than the original ignition temperature after correction and compensation, then using the new air-fuel ratio to replace the original air-fuel ratio. The present application controls the oxygen content of the mixed combustion-supporting air by PID control, so that the mixed combustion-supporting air becomes a stable mixed combustion-supporting air with high oxygen content, and uses large-period offset to adjust the small-period fluctuation of ignition delay, and after several rounds of large-period, the temperature compensation caused by flow rate change and speed change is corrected, and according to the large-period ignition temperature, the stable mixed air and coal gas are used for air-fuel ratio optimization, which is suitable for wide promotion.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of blast furnace metallurgy, in particular to a sintering process oxygen-enriched combustion air-fuel ratio optimization method. BACKGROUND

[0002] Oxygen-enriched combustion is one of the mainstream energy-saving technologies in modern combustion. Oxygen-enriched combustion technology can lower the ignition point of fuel, accelerate the combustion speed, promote complete combustion, increase flame temperature, reduce the amount of flue gas after combustion, improve heat utilization rate, and reduce excess air coefficient. It is called "resource creative technology" by developed countries. The mechanism of oxygen-enriched combustion technology is understood to some extent, and some practical research has been conducted in actual engineering.

[0003] The energy consumption of the sintering process accounts for about 9% of the total energy consumption of steel production, and the sintering waste gas accounts for 45% of the total waste gas of the steel industry. Sintering oxygen-enriched ignition uses oxygen-enriched air obtained by mixing industrial pure oxygen with conventional air, and low-calorific-value fuel gas to achieve efficient ignition of low-calorific-value fuel gas, thereby reducing sintering ignition gas consumption, strengthening the surface fuel combustion process, reducing sintering process solid consumption, and reducing the emission of pollutants such as CO in the sintering process. It has a significant effect on reducing the production cost of sinter, reducing the emission of pollutants and carbon emissions in the sintering process, and improving the profitability and technological upgrading of enterprises.

[0004] The existing oxygen-enriched combustion air-fuel ratio optimization technology uses manual exploration, has poor accuracy, and takes a long time to optimize. In actual use, due to the fluctuation of oxygen, the fluctuation of mixed combustion air and coal gas, and the hysteresis effect, it is often stopped abruptly. SUMMARY

[0005] The sintering process oxygen-enriched combustion air-fuel ratio optimization method proposed by the present application solves the above problems.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A sintering process oxygen-enriched combustion air-fuel ratio optimization method, comprising the following steps:

[0008] Step 1: control the oxygen content of the mixed combustion air by PID, set the oxygen content so that the mixed combustion air becomes a stable mixed combustion air with high oxygen content;

[0009] Step 2: according to the site conditions, when the air pressure > 3k, the coal gas pressure > 4.5k, the average ignition temperature > the set temperature, and the stable running time interval > 4h, trigger the air-fuel ratio optimization;

[0010] Step three, keeping the gas opening unchanged, increasing or decreasing the mixed combustion air volume, after t period time, if the ignition temperature is higher than the original ignition temperature after correction and compensation, the new air-fuel ratio is used to cover the original air-fuel ratio, and the t period is 120 seconds;

[0011] If the ignition temperature is lower than the original ignition temperature after correction and compensation, the original air-fuel ratio is restored.

[0012] In each optimization process, 4-5 t periods are experienced, and the optimization is terminated.

[0013] Preferably, the speed temperature compensation = k1*(current cycle speed-last cycle speed) / last cycle speed*last cycle temperature.

[0014] Preferably, the flow temperature compensation = k3*(k4*k2*flow deviation e+(1-k2)*70*flow deviation rate ek).

[0015] Preferably, the flow deviation e = current cycle flow-last cycle flow, the current cycle flow is the average of the numbers taken every second in the first 50 seconds, and the last cycle flow is the average of the numbers taken every second in the last 20 seconds.

[0016] Preferably, the flow deviation rate ek = (100 second flow value-75 second flow value) / 25, the value in a period of 120 seconds.

[0017] Preferably, the optimization temperature comparison is: Tm = current cycle temperature T2-last cycle temperature T1 + speed temperature compensation-flow temperature compensation+Δt.

[0018] Preferably, K1 = 0.85, k2 = 0.4, k3 = 0.55 k4 = 1.05 Δt = 2℃.

[0019] The beneficial effects of the present application are:

[0020] The purpose of the present application is to control the oxygen content of the mixed combustion air by PID control, so that the mixed combustion air becomes a kind of stable mixed combustion air with high oxygen content, the number of oxygen and combustion air fluctuation factors is reduced, in the case of stable on-site, the large period is used to offset the small period adjustment lag, after several rounds of large period, the temperature compensation caused by flow change and speed change is corrected, and the stable mixed air is used for air-fuel ratio optimization with coal gas according to the large period ignition temperature.

[0021] The present application has the advantages of simple structure, no need to increase new detection equipment, combining oxygen flow factor and combustion air factor into one factor of mixed combustion air, reducing fluctuation factor, offsetting the hysteresis caused by large period t adjustment change, simulating human operation behavior, and realizing and adjusting air-fuel ratio through computer computing power.

[0022] The present application realizes the oxygen-rich ignition air-fuel ratio optimization under the complex sintering gas environment, and optimizes the combustion effect.

[0023] The present application realizes the air-fuel ratio optimization under the complex condition, and lays a foundation for the automatic intelligent temperature control of sintering ignition.

[0024] The present application reduces the coal gas consumption and the sintering ignition carbon emission.

[0025] The present application improves the sintering surface ignition effect, reduces the sintering return ore, and is suitable for wide promotion. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 It is the oxygen pipeline PID control pipeline structure diagram of the present application.

[0027] Fig. 2 It is the action relationship flow chart of the present application.

[0028] In the figure: 1-take oxygen point, 2-fore stop valve, 3-filter, 4-pressure stabilizing valve, 5-gas flow meter, 6-pressure transmitter, 7-temperature transmitter, 8-pneumatic regulating valve, 9-pneumatic quick cut valve, 10-one-way valve, 11-post stop valve, 12-pressure gauge, 13-arrester, 14-oxygen mixer, 15-laser analyzer, 16-nitrogen purge valve, 17-nitrogen gas source, 18-dispersion port, 19-dispersion valve. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments.

[0030] Referring to Figs. 1-2 , a sintering process oxygen-rich combustion air-fuel ratio optimization method, wherein the leftmost end of the PID control pipeline is the oxygen taking point, the pipeline is sequentially connected from left to right and installed with a fore stop valve 2, a filter 3, a pressure stabilizing valve 4, a gas flow meter 5, a pressure transmitter 6, a temperature transmitter 7, a pneumatic regulating valve 8, a pneumatic quick cut valve 9, a one-way valve 10, a post stop valve 11, a pressure gauge 12, an arrester 13, an oxygen mixer 14, and a laser analyzer 15, a nitrogen purge valve 16 is connected between the fore stop valve 2 and the filter 3, a nitrogen gas source 17 is connected to the nitrogen purge valve 16, a dispersion valve 19 is connected between the one-way valve 10 and the post stop valve 11, and a dispersion port 18 is connected to the dispersion valve 19.

[0031] The method comprises the following steps:

[0032] Step one: the oxygen content of the mixed combustion-supporting wind is controlled by PID, and the oxygen content is set so that the mixed combustion-supporting wind becomes a kind of stable mixed combustion-supporting wind with high oxygen content;

[0033] Step two, according to the field conditions, when the air pressure > 3k, the gas pressure > 4.5k, the ignition average temperature > the set temperature and the stable operation time interval > 4h, trigger the air-fuel ratio optimization;

[0034] Step three, keep the gas opening unchanged, increase or decrease the mixed combustion air volume, after t period of time, if the ignition temperature is higher than the original ignition temperature after correction and compensation, then use the new air-fuel ratio to cover the original air-fuel ratio, the t period is 120 seconds;

[0035] If the ignition temperature is lower than the original ignition temperature after correction and compensation, then restore the original air-fuel ratio;

[0036] In each optimization process, 4-5t periods are experienced, and the optimization is terminated.

[0037] Speed temperature compensation = k1 * (current cycle speed - last cycle speed) / last cycle speed * last cycle temperature.

[0038] Flow temperature compensation = k3 * (k4 * k2 * flow deviation e + (1-k2) * 70 * flow deviation change rate ek).

[0039] Flow deviation e = current cycle flow - last cycle flow, the current cycle flow is the average of 50 seconds, and the last cycle flow is the average of 20 seconds.

[0040] Flow deviation change rate ek = (100 second flow value - 75 second flow value) / 25, the value in 120 seconds period.

[0041] Optimization temperature comparison is: Tm = current cycle temperature T2 - last cycle temperature T1 + speed temperature compensation - flow temperature compensation + Δt.

[0042] K1 = 0.85, k2 = 0.4, k3 = 0.55 k4 = 1.05 Δt = 2℃.

[0043] The present application uses PID control oxygen, sets the mixed combustion oxygen content, combines oxygen flow factor and combustion air factor into mixed combustion air factor, reduces the number of influence factors, uses large cycle t to offset the time lag caused by small cycle adjustment, uses the parameter comparison between mixed combustion air and gas to ignite temperature, and eliminates the temperature influence caused by speed, flow and pressure fluctuation.

[0044] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A sintering process oxy-combustion air-fuel ratio optimization method, characterized by It comprises the following steps: Step one, set the oxygen content of the mixed combustion air by PID control, so that the mixed combustion air becomes a stable mixed combustion air with high oxygen content; Step two, trigger the air-fuel ratio optimization according to the site conditions when the air pressure > 3k, the gas pressure > 4.5k, the average ignition temperature > the set temperature, and the stable running time interval > 4h; Step three, keep the gas opening unchanged, increase or decrease the mixed combustion air volume, and after t period of time, if the ignition temperature after correction and compensation is higher than the original ignition temperature, use the new air-fuel ratio to cover the original air-fuel ratio, wherein the t period is 120 seconds; If the ignition temperature after correction and compensation is lower than the original ignition temperature, restore the original air-fuel ratio; In each optimization process, 4-5t periods are experienced, and the optimization is terminated.

2. The sintering process oxycombustion air-fuel ratio optimization method according to claim 1, characterized in that: Speed temperature compensation = k1 * (current cycle speed - last cycle speed) / last cycle speed * last cycle temperature.

3. The sintering process oxycombustion air-fuel ratio optimization method according to claim 2, characterized in that: Flow temperature compensation = k3 * (k4 * k2 * flow deviation e + (1-k2) * 70 * flow deviation change rate ek).

4. The sintering process oxycombustion air-fuel ratio optimization method according to claim 3, characterized in that: Flow deviation e = current cycle flow - last cycle flow, wherein the current cycle flow is the average of the numbers taken every second in the first 50 seconds, and the last cycle flow is the average of the numbers taken every second in the last 20 seconds.

5. The sintering process oxycombustion air-fuel ratio optimization method according to claim 4, characterized in that: Flow deviation change rate ek = (100 second flow value - 75 second flow value) / 25, the value in 120 second period.

6. The sintering process oxycombustion air-fuel ratio optimization method according to claim 5, characterized in that: Optimization temperature comparison: Tm = current cycle temperature T2 - last cycle temperature T1 + speed temperature compensation - flow temperature compensation + Δt.

7. The sintering process oxycombustion air-fuel ratio optimization method according to claim 6, characterized in that: K1 = 0.85, k2 = 0.4, k3 = 0.55, k4 = 1.05, Δt = 2℃.

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