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Psa oxygen generating equipment oxygen-enriched coal injecti

Time:2014-08-13 14:41 Hit:

Oxygen-enriched blast furnace blower is to point to to add industrial oxygen blast furnace, the oxygen content in air blast over the oxygen content of the atmosphere. Blast furnace using oxygen-enriched air blast can accelerate the combustion of carbon, in the case of fuel ratio constant increase production. But the oxygen-enriched air blast reduce into blast furnace air volume, heat into the blast furnace is also reduced. Therefore, the rate of oxygen enriched blast furnace blower has been limited.

Oxygen-enriched air blast blast furnace's aim is to: improve the smelting intensity; Increase production; Strengthen injection fuel burning in front of the tuyere.

1 oxygen-enriched air blast effect on blast furnace

1.1 improve the smelting intensity. Oxygen levels increase due to the wind, thus required airflow to reduce iron per ton. If the air flow into the unchanged, smelting intensity can be improved.

1.2 conducive to the blast furnace anterograde. After oxygen enrichment into nitrogen decreased, so reduce the amount of gas the unit of pig iron, oxygen-enriched blast and constant air volume, pressure differential is reduced, along the line.

1.3 improve the theoretical combustion temperature. Although air volume decrease after oxygen enriched blast to reduce quantity of heat, but the amount of gas is reduced, thus can improve the theoretical combustion temperature.

1.4 increase the CO content in the gas, which is beneficial to indirect reduction. Oxygen-enriched air blast changed the proportion of CO and N2 gas, CO, is conducive to the development of indirect reduction. When the oxygen-enriched air blast combined with fuel injection, hearth gas of CO and H2 increases, more favorable to indirect reduction.

1.5 reduce the flue gas temperature. Oxygen-enriched unit cast iron after reduced the volume of gas, the upper heat exchange area expanded, flue gas temperature decrease. High concentration in the lower part of blast furnace, which make the blast furnace vertical temperature field changing. The influence and the influence of injection fuel instead, thus oxygen-enriched air blast combined with injection fuel can be complementary advantages

Two features of oxygen-enriched coal injection in blast furnace smelting

Oxygen-enriched air blast makes theoretical combustion temperature, smaller blast air enthalpy, and reduced the volume of gas, high temperature down, the roof temperature is reduced, smelting travel faster, furnace charge in furnace for a shorter time; And coal injection is lower the theoretical combustion temperature, blast air enthalpy change, the gas volume increasing, center air development, hearth temperature uniformity, high and medium temperature area expanded, top temperature, reduce coke rate, stock column ore focal ratio increases, the burden retention time in the oven. Visible oxygen enrichment and coal injection for blast furnace smelting process of the parameter is on the contrary, the influence of the combination can foster strengths and circumvent weaknesses, better play to the efficiency of the blast furnace. Oxygen-enriched blast furnace coal injection after smelting characteristics:

2.1 increase the coke combustion rate, increase significantly.

2.2 the pulverized coal gasification and combustion of the spray charging cylinder, and does not reduce the theoretical combustion temperature and enlarge the coal injection volume, so as to further reduce the coke ratio. )

2.3 both can improve the combination of the blast furnace anterograde.

3 the operating characteristics of oxygen-enriched coal injection

As blowing oxygen content and the increase of the quantity of coal injection, blast furnace smelting trip such as burden and gas flow distribution, the change of the temperature field in the furnace and reduction and the heat exchange process were altered obviously, therefore, must correctly grasp the oxygen-enriched coal injection characteristics and adjust in a timely manner to take appropriate control method to control the furnace condition stable anterograde and optimal production index. The main operating characteristics are the following several aspects:

3.1 maintain appropriate theoretical combustion temperature. Grosvenor LTD oxygen coal injection, such as the theoretical combustion temperature is too low, will make the pulverized coal combustion is incomplete, insufficient burden caused by the heating and reduction caused by furnace cooling; Such as the theoretical combustion temperature is too high, will cause the furnace condition.

With the improving oxygen blast it, meet the normal smelting needs theoretical combustion temperature is increased. In addition to increasing coal injection amount need to maintain high combustion temperature, but also because of tons TieMei volume decreases must raise the hearth temperature gas, the corresponding increase in tons of iron gas enthalpy, to satisfy the burden heating and reducing the required heat.

3.2 by means of top and bottom adjust control reasonable gas flow distribution. Oxygen-enriched blast furnace blower, because of the reduced nitrogen, oxygen concentration increased, the unit of cast iron gas volume reduction, such as the tuyere area is the same, pneumatic drum can decrescent, can cause the edge flow development, center accumulation. After the blast furnace coal injection, for pulverized coal volatile flux is much higher than these combustible material in front of the tuyere coke decompose rapidly, produce the gas volume increasing, coal injection, the more the more proportion of bituminous coal, the greater the volume of gas, can cause the edge is aggravating, excessive development center. And the oxygen enrichment and coal injection volume, that coke load stock column permeability variation. Oxygen-enriched blast furnace coal injection to correctly handle the relationship between the above parameters, the key to control the right pneumatic drum can.

Oxygen-enriched coal injection, because of the increasing amount of coal injection, instead of coke is also more and more. Cause stock column permeability is getting worse, especially pay attention to the center open air. Should keep unchanged stock column of coke and adjust the amount of ore, the biggest mining group, is to reduce the ore focal interface reaction. Grosvenor LTD oxygen after the big coal injection, but also should pay attention to maintain proper airflow around the edge.

3.3 maintain excess oxygen coefficient. To make the pulverized coal burning in front of the tuyere completely, need to control the excess oxygen coefficient. Under the certain condition of smelting, excess oxygen coefficient related with coal powder injection quantity, number of spray gun. A certain amount of pulverized coal injection in the, air spray mouth too much oxygen excess coefficient is too high. So increase the quantity of coal injection tuyere is making a big coal injection quantity, improving the pulverized coal combustion, the important measure to improve the coal replacement ratio.

The excess oxygen coefficient of coal injection should not be less than 1.15. All uniform tuyere coal injection can not only improve make excess oxygen coefficient, and makes the theoretical combustion temperature of tuyere, hearth working uniform, to enlarge the injection quantity, increase the combustion rate.

3.4 increase the rate of pulverized coal combustion. Oxygen-enriched blast oxygen concentration, accelerate the pulverized coal combustion, increase the combustion rate. With the blast oxygen raise coal injection ratio increase, swirl pulverized coal combustion rate in the area also increased significantly. In 400 mm from tuyere raceway end, ordinary blast, pulverized coal combustion rate is highest do not exceed 70%, and after the oxygen-enriched air blast, its burning rate is rapidly increased to more than 80%, some of them has reached to 90%. Although single gun coal injection quantity increased, and the combustion rate of the position of the peak general migration at the end of the increase of oxygen to the tuyere with the wind.

3.5 improve the permeability of stock column. All measures to boost the stock column permeability of concentrate, high pressure, add nut coke deposits, etc., to improve oxygen enrichment rate, increasing coal injection quantity and improve the effect of oxygen-enriched coal injection, in a timely manner the net slag, iron is also an important measure to improve the lower permeability fluid permeability.

4 oxygen-enriched coal injection operation of furnace temperature control and regulate

The basic operation of blast furnace smelting system even perfectly reasonable, but due to the influence of various factors, furnace condition will often appear different degree of volatility. It clearly reflected in the hearth balance is destroyed, caused by temperature fluctuations.

The change of temperature, inevitably leads to the gas temperature, the change of the size and its distribution, caused by cutting speed and the change of the heating and reduction of the ore. These changes in turn lead to hearth temperature and heat bigger changes, if not timely correcting, certainly will cause a vicious cycle, leading to serious disorder of furnace condition. As a result, the operator must accurately judging furnace condition, skillfully mastering various relief means, especially the lower adjusting methods such as air volume and air temperature, moisture, rich oxygen, the quantity and the characteristics of coal injection, timely and correctly applied, which can quickly to correct wrong stroke, blast furnace and can avoid again cause furnace condition fluctuation, constantly maintain stability of the blast furnace anterograde.

Injection of pulverized coal in the hearth burning gives off heat, therefore, adjust the quantity of coal injection can also correct the furnace temperature fluctuation, the correct rate, depending on the coal injection of water, ash and calorific value, hydrocarbon ratio and the gas utilization degree of H2.

Practice also proved that coal injection correction of temperature fluctuations in efficiency, decrease with the increase of the injection quantity, because, with the increase of injection volume, injection content of heat energy utilization is reduced, the replacement ratio with the increase of coal injection quantity and decline (see chart 1).

Table 1 coal injection and displacement ratio

Injection quantity/kg. T - 1 20 40 to 60, 80

Replacement ratio of 0.90 0.85 0.80 0.75 0.70

Using coal injection volume of dispensing, for heating and coal gasification and absorption of heat, burning cause the change of the gas volume, so as the wind moderate moisture adjust flexibly. Such as the furnace cooling with coal, not immediately stop the cool. Feeding too much may cause temporary cooler. Gas increase at the same time, adverse to the anterograde. On the other hand, the furnace thermal coal, not immediately stop the thermal potential.

Coal injection in the furnace combustion, consume oxygen in the blast, therefore, to adjust the injection quantity, influence burden descent speed, increase the feeding speed slow injection quantity, reduce feed speed to speed up the injection quantity. Equipped with oxygen-enriched degree will be more obvious at the same time, add oxygen feeding speed is accelerated, the opposite is reduced, therefore, oxygen-enriched coal injection of dispensing, in particular, should be controlled strictly. Expand the coal injection volume of operation, to improve the thermal system in the main adjustment of the load, should be implemented step by step, such as the original 80 kg/t coal injection ratio increased to 120 kg/t level, can increase the quantity of coal every 10 kg/t, gradually increase the points steps, and each step should be stable for smelting cycle or 1 ~ 2 days, to a new level increasing coal injection quantity.

Big operation, injection quantity in the furnace temperature control, average suddenly changed to cope with external conditions, bring the influence of furnace temperature. To reduce or stop in time when the load adjustment of injection pulverized coal, a large number of injection, to reduce or stop shall be adding coke, adding the number of coke except in displacement than the relevant to consider the time of the gas utilization, feeding speed and length of stop blowing:

Adding coke injection fuel quantity x = it can reduce the displacement than x of coke

Stop blowing smelting cycle time, should press burn smelting process.