UA9052U - Method for automatic control of purification of products of melting of steel furnaces - Google Patents

Abstract

The method of automatic control of cleaning the gaseous products of melting steel furnace includes the transportation through the smoke circuit of the dust-laden gases, their supply for cleaning into the high-pressure Venturi tubes of scrubber, subsequent overheating, ejection with the help of the exhauster through the chimney into the atmosphere. In this case, the quantity of water supplied into the high-pressure Venturi tubes for settling of the dust is changed proportional to the square of oxidizer consumption into the bath of furnace during melting.

Description

Description of the invention

A useful model applies to the ferrous metallurgy industry and can be used in the purification of dusty 2 gases from floor steel furnaces.

There is a known method of controlling the cleaning of gases from dust, in which the supply of water for spraying is carried out depending on the median size of the dust particles | see and. with. number USSR Mo 1519761 MKV VO1D51/081I.

The reason that prevents the achievement of the given task by a known technical solution is, on the one hand, the homogeneity of the fractional size of the dust particles: settling of large dust particles occurs in the 70 gas discharge tract of the steel-smelting furnace (slags, beds, gas ducts), which turns out to be a stage for rough cleaning of dusty gases; gaseous products of melting, which contain fine dust with an average particle size of 0.25-0.40 microns, enter the gas cleaner; on the other hand, the lack of control of the median particle size does not allow to control the degree of purification of dusty gases in the course of melting by changing the amount of circulating water supplied to the venturi tubes. 19 A known method of automatic regulation by cleaning dusty gases in wet gas cleaning devices, in which the flow of water supplied for cleaning is kept constant for the entire range of flue gas flow rates. When the water flow deviates from the set value, the regulator works out a series of pulses of a certain size and duration, moving the regulating throttle on the water pipeline until the set water flow is restored | see Yu. D. Glebov. Control and automatic management of gas cleaning devices. - M.:, Metallurgy, 1982, pp. 204-205).

The reason that prevents the achievement of the technical result by the closest analogue is the lack of a relationship between the amount of water supplied to the gas purifier and the degree of dustiness of the flue gases (the dust content in the gaseous products of melting changes during the course of melting and increases sharply with an increase in the oxygen consumption during blowing it into the furnace bath; at the entrance to the gas cleaner, the dust content of gases during oxygen injection is 3-6bg/m7, and between injection - 0.4-0.g/m3), which causes an increase in water consumption for cleaning, a significant reduction temperature of flue gases, increase in fuel consumption to heat them above the dew point, corrosive operation of equipment and gas ducts, harmful effect of droplet moisture contained in the gases on the laying of the smoke pipe.

The basis of the useful model is the task of developing a method of automatic control of cleaning cm 3o of gaseous melting products of a steel-smelting furnace, which allows to reduce the water consumption for the cleaning of dusty gases, reduce the consumption of electricity and fuel, and increase the durability of the furnace masonry and chimney. at

The technical task is achieved by the fact that in the known method of controlling the cleaning of gaseous Ge») products of melting of a steel smelting furnace, which includes the transportation of dusty gases formed during the use of an oxidizing agent in the course of melting through the smoke path, their supply for cleaning to the high-pressure Venturi tubes of the gas cleaner, subsequent overheating above the dew point due to the burning of gaseous fuel in the sub-furnace, the amount of water supplied to the high-pressure Venturi tubes for dust deposition is changed proportionally to the squared flow rate of the oxidizer in the furnace bath during melting, and the heat load on the sub-furnace is adjusted according to this temperature of the smoke gases at the foundations of the chimney. 70 General features for the known and proposed method of automatic control of the cleaning of gaseous products of melting of a steel furnace are the following essential features: c - transportation of dusty gases through the smoke path; - supplying them for cleaning in the high-pressure Venturi tubes of the gas cleaner; - subsequent overheating above the dew point due to the burning of gaseous fuel in the furnace; c 15 - emission of dusty gases with the help of an exhauster through a chimney into the atmosphere.

The essential features of the proposed method of automatic control (ав) of the cleaning of gaseous products of melting of a steel-smelting furnace that are different from the closest analogue are: sl - the amount of water supplied to the high-pressure Venturi tubes for dust deposition, changes proportionally to the squared consumption of the oxidizer in the furnace bath during melting;

What) 50 - the heat load on the furnace is adjusted according to the temperature of the flue gases at the base of the flue.

The presence of these features allows us to classify a useful model as meeting the "novelty" criterion.

The specified set of essential features will ensure a reduction in water consumption, a reduction in electricity consumption, fuel savings, and an increase in the durability of the refractory lining of the furnace and chimney.

Reduction of water consumption for wet cleaning of dusty gases, reduction of electricity consumption by

With the electric motors of exhaust fans and water pumps, saving fuel during steel smelting and increasing the durability of refractory masonry of steel-smelting furnaces is achieved by the fact that the amount of water supplied to the high-pressure Venturi tubes of the gas cleaner for dust deposition changes proportionally to the squared consumption of the oxidizer in the furnace bath during melting, and the heat load on the furnace is adjusted according to the temperature of the flue gases at the base of the chimney. because the change in the amount of water supplied to the high-pressure venturi tubes of the gas purifier, in proportion to the squared consumption of the oxidizer in the furnace bath during melting, is explained (while maintaining the degree of flue gas purification) by the need for: - a decrease in the volume of the steam-gas mixture entering the exhauster inlet; - minimization of its temperature decrease and hydraulic resistance of the flue system "stove - chimney"; because - improving the aerodynamics of the working space of the steel furnace.

The automatic adjustment of the heat load on the sub-fireplace according to the temperature of the flue gases at the base of the chimney is explained by the need to maintain the temperature of the flue gases above the dew point in conditions of variable humidity to prevent the corrosive operation of the gas tract and the exhauster, as well as the destruction of the smoke pipe with minimal fuel consumption on the sub-fireplace.

The supply of water to the high-pressure venturi tubes in an amount proportionally smaller than the square of the oxidizing agent consumption in the furnace bath during melting causes a deterioration in the quality of cleaning dusty gases, an increase in their temperature, overheating and premature failure of the exhauster blades.

The supply of water to the venturi tubes in an amount proportionally larger than the square of the oxidizer consumption in the furnace bath in 70 times of melting causes an increased water consumption, a significant increase in the volume of flue gases and a decrease in their temperature, as a result of which the fuel consumption of the furnace and sub-heater will increase, as well as the consumption of electricity on the electric motors of the exhaust fan and water pumps.

In Fig. the block diagram of the system of automatic control of the purification of gaseous products of melting of the steel furnace is shown.

It accommodates the main circuit of the furnace 1, oxygen blowing nozzles 2, air valves C and dampers 4 on the smoke exhaust path of the furnace, gas fan 5, boiler and smoke dampers b on the common bed, boiler-utilizer 7, gas cleaner 8, furnace 9, exhauster 10 and chimney 11.

The constituent elements of the system are flow meters of oxidizer 12, fuel 18 and water 15, water flow regulators 13 and fuel 16, water flow 14 and fuel 17 setting devices, as well as a registration device

Temperatures of flue gases at the foundations of the chimney 19.

The method is as follows.

The formation of the signal that controls the supply of circulating water to the Venturi tubes of the gas cleaner 8 is carried out by the regulating controller 13 depending on the flow rate of the oxidizer, which enters the blowing nozzles 2, and the task of the minimum amount of water that ensures the residual dustiness of the flue gases that are emitted into the atmosphere. less than 100 mg/m2, during periods without drafts of furnace operation.

During the periods of blowing the furnace bath with oxygen through nozzles 2 to the input of the controller 13 from the flowmeter 12, a signal proportional to the amount of oxygen supplied to the bath arrives.

The controller 13 processes the received information and in accordance with the algorithm

Mvody--3.698 x 107 x Mo»? in 29.588 x 102 x Moz in 5.084 s forms a signal for controlling the supply of water for flue gas cleaning. yu

When the volume and humidity of flue gases increase, it is necessary to stabilize their temperature at the base of the pipe at a level that exceeds the dew point. (av)

For this purpose, the input of the temperature regulator in the working space of the firebox is fed a correcting signal from the Fu of the temperature recorder at the base of the smoke pipe 19, which allows, due to the change in the amount of fuel supplied to the firebox 9, to maintain the temperature of the flue gases in the smoke pipe higher than the dew point and thereby preventing the harmful effects of condensate containing sulfur compounds.

An example of a specific implementation of the method. "

When smelting in the Marteniv furnace with a Z0Ot steel grade of grade 45 in the non-blowing period (filling) on the s-v setting device for the consumption of water, which is fed to the venturi tubes for flue gas cleaning, the consumption value was established - 20 mU/h. With this consumption of circulating water, the analysis of the flue gas sample at the gas cleaner inlet showed a dustiness value of 0.5-0.6 bg/m7, which does not exceed the permissible level.

During the period of pouring cast iron into the furnace, through the blowing nozzles, 3,000 m3/hour was fed into the furnace bath. oxygen At the same time, the regulating controller set the regulating body on the circulating water pipeline to a position that corresponds to the flow of water to the gas purifier of 40 m3/hour. The analysis of the flue gas sample showed that the dust content of the technological dust and gas emissions was 1.8-3.2 g/m3. o With an increase in the flow of oxygen to the bath during the melting period, the flow of circulating water for wet cleaning of gaseous melting products increases proportionally to the squared flow of oxygen and at Mo»-6.0 thousand mU/h. "from 50, the controller set the amount of water consumption at 140 mU/h.

During the finishing process of melting, when the supply of oxygen to the bath is stopped, the water flow is set at the level of 2 Ω/h. until the end of melting.

During the melting period (refueling, filling, warming up), when oxygen is not supplied to blow the bath, the volume of flue gases after the gas cleaner is 24 Otys.m Z/h, before the exhauster 29 Bths.mZ/h, temperature

The temperature of the flue gases after the venturi tubes decreases to 75-80 °C, while the gas consumption per furnace is 200 m/h. allows you to heat the gases entering the chimney up to 90-10090.

During the melting period with intensive blowing of the liquid bath with oxygen (consumption is equal to 6b, Otys.m Z/h.) with increased water consumption (140 mZ/h) and constant heat load on the sub-furnace (gas consumption 6o 200m/h) the temperature of flue gases decreases to 502С.

After that, a correction signal for the temperature of the flue gases at the base of the chimney is included in the control scheme for the heat load on the sub-furnace, the gas consumption for heating the sub-furnace increases to ZBOmU/h, high-temperature combustion products are mixed with purified March gases in the common gas duct in front of the exhaust fan, which provides an increase in the temperature at the base of the pipe and its stabilization 65 at the level of 95--52С, i.e. higher than the dew point.

Using the proposed method, controlling the supply of water for cleaning dusty flue gases during melting periods depending on the consumption of the intensifier (05) and ensuring stable temperature values higher than the dew point at the base of the smoke pipe allows to reduce the water consumption for cleaning dusty gases by 24 -25956 for melting, to reduce the consumption of electricity for electric motors of the exhaust fan and

water pumps for 15-2095 and fuel for steel smelting for 1.5-2.0 kg per ton, to increase the durability of the refractory masonry of the upper and lower structures of the furnace and the smoke pipe, to ensure the reliable operation of the exhaust hood during the evacuation of wet and aggressive flue gases .

Claims (1)

The formula of the invention is the method of automatic control of the purification of gaseous products of melting of a steel-smelting furnace, which includes the transportation of dusty gases formed during the use of an oxidizing agent for the intensification of melting through the flue, feeding them for purification into the high-pressure venturi tubes of the gas purifier, subsequent overheating /5 Above the dew point due to combustion in the furnace of gaseous fuel, exhaust by means of an exhauster through a smoke pipe into the atmosphere, which differs in that the amount of water supplied to the high-pressure venturi tubes for dust deposition changes proportionally to the squared flow rate of the oxidizer in the furnace bath during melting, and the heat load on the furnace adjusted for the temperature of flue gases in the base of the chimney. that 2 s Zo yu «c) (o) . and? se) («c) 1 Ko) Co 60 b5