CN102952913B - Dual-preheating method and device for preheating blast furnace gas by using heat-storage-type preheating furnace - Google Patents

Abstract

The invention relates to the field of blast furnace hot blast stove preheating, in particular to a double preheating method and device for preheating blast furnace gas by using a regenerative preheating furnace, which is characterized in that part of the blast furnace gas is preheated by using a regenerative preheating furnace To 1000°C-1200°C, the preheated high-temperature gas is mixed with 40-80°C low-temperature gas, and the temperature of the mixed gas is controlled at 300°C-350°C to the hot blast stove; at the same time, the combustion air is preheated to 200°C-230 °C to the hot blast stove, so that the blast furnace blast temperature not lower than 1250 °C can be achieved under the condition of single-fired blast furnace gas. Compared with the prior art, the present invention has the following advantages: 1) It solves the problems existing in the metal heat exchanger, such as easy dust accumulation and clogging, acid corrosion, large system resistance loss, and low preheating temperature. 2) It has the characteristics of high efficiency and practicality. 3) The effect of preheating gas to increase wind temperature is significantly greater than that of preheating air. 4) It is conducive to the stable operation, long life and high efficiency of the ceramic burner of the hot blast stove.

Description

Double preheating method for preheating blast furnace gas with regenerative preheating furnace

technical field

The invention relates to the field of preheating gas for blast furnace hot blast stove and combustion-supporting air, in particular to a double preheating method and device for preheating blast furnace gas by using a regenerative preheating furnace.

Background technique

The most direct way to increase blast furnace blast temperature is to use high calorific value gas as the furnace fuel for hot blast stoves. The high calorific value gas produced by iron and steel complexes includes coke oven gas and converter gas. These high calorific value gases are generally used in rolling mills and civilian use. , seldom used in blast furnace hot blast stove, even if some iron and steel plants can provide a small amount of high calorific value gas to blast furnace hot blast stove, because the tar, dust and acid in the gas are easy to block the channel of hot blast stove checker bricks and cause the surface of checker bricks to slag, Reduce the life and efficiency of the hot blast stove. Therefore, blast furnace gas is generally used as the furnace fuel for hot blast stoves in most blast furnaces at home and abroad.

Another way to increase the blast temperature is to preheat the blast furnace gas and combustion air used in the hot blast stove. This method is especially suitable for iron and steel enterprises that only use blast furnace gas as the fuel for the hot blast stove. Since blast furnace gas is a flammable, explosive and highly toxic gas, in order to prevent explosion and poison, domestic and foreign blast furnace ironmaking industries generally use metal tube heat exchangers or metal plate heat exchangers to preheat blast furnace gas, and the gas preheating temperature At the same time, the temperature of the combustion-supporting air is preheated to above 500°C, so that the air temperature higher than 1250°C can be obtained under the condition of single-fired blast furnace gas. Preheating the combustion-supporting air temperature to above 500°C will bring the following problems: first, the temperature difference between the combustion-supporting air and the gas is too large, and the ceramic burner masonry of the hot blast stove will generate stress, which will affect the life of the ceramic burner; And the valve is designed according to high temperature, which increases investment.

Contents of the invention

The purpose of the present invention is to provide a dual preheating method and device for preheating blast furnace gas by using a regenerative preheating furnace, so as to overcome the easy ash accumulation and blockage in the preheating gas process of metal tube heat exchangers or metal plate heat exchangers , acid corrosion, large system resistance loss, low preheating temperature and other disadvantages; reducing the temperature difference between air and gas is conducive to the stable work, long life and high efficiency of the ceramic burner of the hot blast stove.

In order to solve the problems of the technologies described above, the technical solution of the present invention is:

The dual preheating method of blast furnace gas is preheated by the regenerative preheating furnace. The regenerative preheating furnace is used to preheat part of the blast furnace gas to 1000°C-1200°C. The preheated high temperature gas and the low temperature of 40-80°C Coal gas is mixed, and the mixed gas temperature is controlled at 300°C-350°C to the hot blast stove; at the same time, the combustion-supporting air is preheated to 200°C-230°C to go to the hot blast stove, so that under the condition of single-fired blast furnace gas, it can be achieved not less than 1250 °C blast furnace blast temperature, the specific operation steps are as follows:

1) When the regenerative preheating furnace is in the combustion period, the low-temperature gas inlet shut-off valve and the high-temperature gas outlet shut-off valve are closed, the combustion air inlet shut-off valve, the furnace gas inlet shut-off valve and the flue gas outlet shut-off valve are opened, and the combustion air and flue gas outlet shut-off valves are opened. The gas enters the burner and is fully mixed and then enters the combustion chamber for combustion. The high-temperature flue gas generated enters the regenerator to heat the checkered brick masonry to above 1200°C, and the low-temperature flue gas after heat exchange is discharged through the flue gas outlet;

2) When the regenerative preheating furnace is changed from the combustion period to the air supply period, reduce the opening of the combustion air inlet regulating valve in advance, reduce the excess air coefficient, and control the oxygen content in the residual flue gas in the furnace to be lower than the safe concentration , according to the temperature of the flue gas outlet, it is determined whether to block the furnace or change the furnace;

3) When the regenerative preheating furnace is in the air supply period, open the low-temperature gas inlet shut-off valve and the high-temperature gas outlet shut-off valve, close the combustion air inlet shut-off valve, the furnace gas inlet shut-off valve and the flue gas outlet shut-off valve, part 40 The low-temperature gas of -80°C enters from the bottom of the regenerator, and is heated to high-temperature gas of 1000°C±200°C when passing through the checker brick masonry. Hot gas at ±50°C is sent to blast furnace hot blast stove;

4) When the regenerative preheating furnace is changed from the air supply period to the combustion period, the flue gas is introduced at this time to drive the residual high-temperature gas in the furnace to the high-temperature gas pipeline to realize the recovery of the residual gas, and the flue gas fan, flue gas The outlet shut-off valve and the high-temperature gas outlet shut-off valve, close the combustion-supporting air inlet shut-off valve and the low-temperature gas inlet shut-off valve, the flue gas fan will force the flue gas from the flue gas outlet, and drive the remaining high-temperature gas in the furnace into the high-temperature gas pipeline , when the gas composition in the furnace is less than 1-2%    , the regenerative preheating furnace enters the combustion period and repeats step 1).

When the regenerative preheating furnace is changed from the combustion period to the air supply period, in order to prevent gas explosion and ensure that the gas quality is not affected by the flue gas, use the furnace gas to drive the flue gas into the flue, that is, close the combustion air inlet and cut off Valve, low-temperature gas inlet shut-off valve and high-temperature gas outlet shut-off valve, open the furnace gas inlet shut-off valve and flue gas outlet shut-off valve, drive the residual flue gas in the furnace to the flue, and then change the furnace to the combustion period, burn the furnace gas The closing or delayed closing of the inlet shut-off valve and the flue gas outlet shut-off valve is controlled by the oxygen measuring instrument and gas composition measurement arranged on the flue.

The device adopting the double preheating method of preheating the blast furnace gas by the above-mentioned regenerative preheating furnace, the high temperature gas outlet of the regenerative preheating furnace is connected with the high temperature gas inlet of the mixing chamber through the high temperature gas pipeline, and the low temperature gas inlet of the mixing chamber is connected with the high temperature gas inlet of the mixing chamber The low-temperature gas pipeline is connected, the mixed gas outlet of the mixing chamber is connected to the hot blast stove; the flue gas inlet and outlet of the air heat exchanger are respectively connected to the main flue of the hot blast stove, and the hot air outlet of the air heat exchanger is connected to the hot blast stove.

The structure of the regenerative preheating furnace is one of external combustion, internal combustion or top combustion.

The number of the regenerative preheating furnaces is at least two, and the working system is one burning and one sending.

A flue gas fan is provided at the flue outlet of the regenerative preheating furnace.

The combustion air inlet of the regenerative preheating furnace is sequentially connected with the combustion air inlet cut-off valve and the combustion air regulating valve, and the combustion gas inlet of the regenerative preheating furnace is sequentially adjusted with the burner gas inlet cut-off valve and the burner gas inlet. The valves are connected, and mechanical interlock relief valve 1 and relief valve 2 are respectively provided between the combustion air inlet shut-off valve and the combustion air regulating valve, and between the furnace gas inlet shut-off valve and the furnace gas inlet regulating valve.

The flue of the regenerative preheating furnace is provided with a bursting membrane and a water seal to prevent combustible gas explosion.

Compared with the prior art, the beneficial effects of the present invention are as follows: 1) It solves the problem of easy ash accumulation and blockage, acid corrosion, large system resistance loss, preheating gas process of metal tube heat exchanger or metal plate heat exchanger. low temperature issues. 2) It has the characteristics of high efficiency and practicality. The self-consumption of blast furnace gas in the blast furnace ironmaking process accounts for about 40% of the self-produced gas of the blast furnace, about 30% is sent to other users in the comprehensive iron and steel plant, and 30% is burned and released into the atmosphere or sent to CCPP units For power generation, the efficiency of CCPP unit for power generation is only 40%, which is very low. However, when blast furnace gas is used to heat the preheating furnace, the thermal efficiency can be as high as 80%. Therefore, the present invention has obvious economic benefits and broad application prospects. 3) When the preheating temperature is the same, the effect of preheating gas to increase the wind temperature is obviously greater than that of preheating air. 4) Reducing the temperature difference between air and gas is conducive to the stable operation, long life and high efficiency of the ceramic burner of the hot blast stove, and reduces the investment in combustion air pipes and valves.

Description of drawings

Fig. 1 is a schematic structural diagram of the double preheating flow process of the present invention.

In the figure: 1-regenerative preheating furnace 2-mixing chamber 3-air heat exchanger 4-combustion air pipe 5-hot stove main flue 6-bypass pipe 7-high temperature gas pipe 8-low temperature gas pipe 9 -mixed gas outlet 10-low temperature gas inlet shut-off valve 11-high temperature gas outlet shut-off valve 12-release valve 1 13-release valve 2 14-burner gas inlet shut-off valve 15-burner gas inlet regulating valve 16-combustion fan 17- Combustion air inlet shut-off valve 18-combustion air regulating valve 19-flue gas fan 20-flue gas outlet shut-off valve 21-flue 22-chimney 23-bursting membrane 24-water seal 25-burner gas pipeline 26-bypass valve

Detailed ways

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

See Fig. 1, which is a schematic diagram of the dual preheating process structure of the present invention using a regenerative preheating furnace to preheat blast furnace gas. The high temperature gas outlet of the regenerative preheating furnace 1 passes through the high temperature gas pipeline 7 and the high temperature gas inlet of the mixing chamber 2 The low-temperature gas inlet of the mixing chamber 2 is connected to the low-temperature gas pipeline 8, and the mixed gas outlet 9 of the mixing chamber 2 is connected to the hot blast stove; the flue gas inlet and outlet of the air heat exchanger 3 are connected to the main flue 5 of the hot blast stove respectively, The hot air outlet of the air heat exchanger 3 is connected to the hot blast stove, the air heat exchanger 3 is a plate heat exchanger or a tube heat exchanger, and a bypass pipe 6 is set up in parallel with the air heat exchanger 3 on the main flue 5 of the hot blast stove During normal production, excess flue gas flows through bypass pipe 6, and when air heat exchanger 3 is overhauled, all flue gas of hot-blast stove flows through bypass pipe 6 and enters chimney 22, and bypass pipe 6 is provided with bypass valve 26, uses For the adjustment of bypass flue gas flow. Combustion-supporting blower 16 links to each other with the combustion-supporting air inlet of regenerative preheating furnace 1 through combustion-supporting air pipeline 4, combustion-supporting air inlet cut-off valve 17, combustion-supporting air regulating valve 18. The furnace gas pipeline 25 is connected to the combustion gas inlet of the regenerative preheating furnace 1 through the furnace gas inlet shut-off valve 14 and the furnace gas inlet regulating valve 15, between the combustion-supporting air inlet shut-off valve 17 and the combustion-supporting air regulating valve 18 And between the burner gas inlet cut-off valve 14 and the burner gas inlet regulating valve 15, mechanical interlock type release valve one 12 and release valve two 13 are respectively arranged, and the residual gas and air between the valves are automatically released during furnace change to prevent gas and Interpenetration of air causes explosion.

The structure of the regenerative preheating furnace 1 is an external combustion type (that is, the combustion chamber and the regenerator are separately set) a preheating furnace, and an internal combustion type (that is, the combustion chamber and the regenerator are centrally set, and the combustion chamber and the regenerator are separated by a refractory brick wall). Regenerator isolated) preheating furnace and top-fired (that is, the combustion chamber is set above the regenerator) preheating furnace.

A flue gas fan 19 is provided at the flue outlet of the regenerative preheating furnace 1 . The high-temperature gas pipeline 7 is provided with a gas component detection device. An oxygen measuring instrument and a gas composition measuring device are installed at the exit of the flue. The flue 21 of the regenerative preheating furnace is provided with a bursting membrane 23 and a water seal 24 to prevent the explosion of combustible gas. Once the system explodes and the system pressure exceeds the limit, the explosion-proof membrane and water seal will automatically open and release the pressure to ensure the entire System security.

In the flow process of the present invention, at least two regenerative preheating furnaces are needed, and the working system of the regenerative preheating furnace 1 and the regenerative preheating furnace 1' is one burning and one delivery.

The double preheating method of the present invention is to use a regenerative preheating furnace to preheat part of the blast furnace gas to 1000°C-1200°C, mix the preheated high-temperature gas with 40-80°C low-temperature gas, and the temperature of the mixed gas Control at 300°C-350°C to the hot blast stove; at the same time, use the hot blast stove flue gas and metal heat exchanger to preheat the combustion air to 200°C-230°C to the hot blast stove, because the amount of blast furnace gas used by the hot blast stove is the weight of the combustion air 2 times, and under the same conditions, the specific heat of blast furnace gas is higher than that of air. Therefore, when the preheating temperature is the same, the effect of preheating gas on increasing the wind temperature is significantly greater than that of preheating air. In this way, under the condition of single-fired blast furnace gas, different For the blast furnace blast temperature lower than 1250℃, the specific operation steps are as follows:

1) When the regenerative preheating furnace is in the combustion period, the low-temperature gas inlet shut-off valve 10 and the high-temperature gas outlet shut-off valve 11 are closed, the combustion air inlet shut-off valve 17, the furnace gas inlet shut-off valve 14 and the flue gas outlet shut-off valve 20 When it is turned on, the combustion-supporting air and gas enter the burner to fully mix and then enter the combustion chamber for combustion. The high-temperature flue gas generated enters the regenerator to heat the checker brick masonry to above 1200. The low-temperature flue gas after heat exchange passes through the flue 21 and the chimney 22 emissions;

2) When the regenerative preheating furnace is changed from the combustion period to the air supply period, reduce the opening of the combustion air inlet regulating valve 18 in advance, reduce the excess air coefficient, and control the oxygen content in the residual flue gas in the furnace to be lower than the safe Concentration, according to the temperature of the flue gas outlet to determine the furnace or change the furnace;

3) When the regenerative preheating furnace is in the air supply period, open the low-temperature gas inlet shut-off valve 10 and the high-temperature gas outlet shut-off valve 11, close the combustion air inlet shut-off valve 17, the furnace gas inlet shut-off valve 14 and the flue gas outlet shut-off Valve 20, part of the 40-80°C low-temperature gas enters from the bottom of the regenerator, and is heated to 1000°C ± 200°C high-temperature gas when passing through the checker brick masonry, and the high-temperature gas enters the mixing chamber 2 through the high-temperature gas pipeline 7, and 40 -80°C low-temperature gas is mixed into hot gas at 300°C±50°C and sent to the hot blast stove;

4) When the regenerative preheating furnace is changed from the air supply period to the combustion period, the flue gas is introduced at this time to drive the residual high-temperature gas in the furnace to the high-temperature gas pipeline 7 to realize the recovery of the residual gas, and the flue gas fan 19, The flue gas outlet shut-off valve 20 and the high-temperature gas outlet shut-off valve 11 are closed, the combustion-supporting air inlet shut-off valve 17 and the low-temperature gas inlet shut-off valve 10 are closed, and the flue gas fan 19 forces the flue gas from the flue gas outlet to dissipate the remaining high temperature in the furnace The gas is driven into the high-temperature gas pipeline 7, and the gas composition detection is installed in the branch pipe of the high-temperature gas outlet to determine whether there is residual gas in the furnace. When the gas composition in the furnace is less than 1-2%, the regenerative preheating furnace 1 switches to the combustion period , repeat step 1).

When the regenerative preheating furnace is changed from the combustion period to the air supply period, the residual gas in the furnace is high-temperature flue gas, and the flue gas contains about 4% oxygen. When the gas enters the furnace, local combustion or even explosion will occur. And when residual flue gas enters in the coal gas, the quality of the gas will be affected. To prevent the gas from exploding and ensure the quality of the gas is not affected by the flue gas, burn the furnace gas to drive the flue gas into the flue, that is, close the combustion-supporting air inlet shut-off valve 17, The low-temperature gas inlet shut-off valve 10 and the high-temperature gas outlet shut-off valve 11 are opened, the furnace gas inlet shut-off valve 14 and the flue gas outlet shut-off valve 20 are opened, and the residual flue gas in the furnace is driven into the flue 21, and then the furnace is switched to the combustion period , The closing or delayed closing of the burner gas inlet cut-off valve 14 and the flue gas outlet cut-off valve 20 is controlled by the oxygen measuring instrument set on the flue branch pipe and the gas composition measurement (measurement of CO concentration).

Claims (1)

1. adopt two pre-heating means of heat accumulating type preheating oven preheating blast furnace gas, it is characterized in that, adopt two pre-heating means of heat accumulating type preheating oven preheating blast furnace gas, adopt heat accumulating type preheating oven that part blast furnace gas is preheated to 1000 DEG C-1200 DEG C, coal gas of high temperature after preheating mixes with the low temperature coal gas of 40-80 DEG C, and mixed gas temperature controls at 300 DEG C-350 DEG C wind furnaces that reduce phlegm and internal heat; Combustion air is preheated to 200 DEG C-230 DEG C wind furnaces that reduce phlegm and internal heat, under single fire blast furnace gas condition, just can realize the blast furnace blast temperature being not less than 1250 DEG C like this, its concrete operation step is as follows simultaneously:

1) when heat accumulating type preheating oven is in main combustion period, low temperature coal gas entrance trip valve and coal gas of high temperature outlet trip valve are closed, combustion air inlet trip valve, burning producer gas entrance trip valve and exhanst gas outlet trip valve are opened, combustion air and coal gas enter burner and fully mix and enter combustion chambers burn again, the high-temperature flue gas produced enters regenerator and checker brickwork is heated to more than 1200 DEG C, and the low-temperature flue gas after heat exchange discharges through exhanst gas outlet;

2) when heat accumulating type preheating oven by main combustion period to when on air changing stove, reduce combustion air inlet control valve opening in advance, reduce coefficient of excess air, in control stove, in residual flue gas, oxygen level is lower than safe concentration, and the temperature according to exhanst gas outlet determines cold stoking or changes stove;

3) when heat accumulating type preheating oven is on air, open low temperature coal gas entrance trip valve and coal gas of high temperature outlet trip valve, close combustion air inlet trip valve, burn producer gas entrance trip valve and exhanst gas outlet trip valve, the low temperature coal gas of part 40-80 DEG C enters by below regenerator, the coal gas of high temperature of 1000 DEG C-1200 DEG C is heated to when checker brickwork, coal gas of high temperature enters mixing section through pipeline, and the heating gas being mixed into 300 DEG C-350 DEG C with 40-80 DEG C of low temperature coal gas gives blast funnace hot blast stove;

4) when heat accumulating type preheating oven is by when on air changing stove to main combustion period, now introduce flue gas and coal gas of high temperature residual in stove is driven the recovery realizing residual coal gas to high temperature gas line, open flue gas blower fan, exhanst gas outlet trip valve and coal gas of high temperature outlet trip valve, close combustion air inlet trip valve and low temperature coal gas entrance trip valve, flue gas is forced to pass into from exhanst gas outlet by flue gas blower fan, the coal gas of high temperature remained in stove is driven in high temperature gas line, when in stove, gas composition is less than 1-2%, heat accumulating type preheating oven proceeds to main combustion period, repeating step 1);

When heat accumulating type preheating oven by main combustion period to when on air changing stove, for preventing gas explosion and ensureing gas quality not by the impact of flue gas, flue gas is driven in flue with burning producer gas, namely combustion air inlet trip valve is closed, low temperature coal gas entrance trip valve and coal gas of high temperature outlet trip valve, open and burn producer gas entrance trip valve and exhanst gas outlet trip valve, flue gas residual in stove is driven in flue, then change stove and proceed to main combustion period, burn the closedown of producer gas entrance trip valve and exhanst gas outlet trip valve or time-delay closing to be controlled by oxygen determination instrument that flue is arranged and gas composition measurement,

Realize the device of two pre-heating means of described heat accumulating type preheating oven preheating blast furnace gas, the coal gas of high temperature outlet of heat accumulating type preheating oven is connected with the coal gas of high temperature entrance of mixing section by coal gas of high temperature pipeline, the low temperature coal gas entrance of mixing section is connected with low temperature coal gas pipeline, and the mixed gas outlet of mixing section connects hotblast stove; The smoke inlet of air heat exchanger is connected with hotblast stove flue collector respectively with outlet, and the hot air outlet of air heat exchanger connects hotblast stove;

The combustion air inlet of described heat accumulating type preheating oven is connected with combustion air variable valve with combustion air inlet trip valve successively, the burning gas entry of heat accumulating type preheating oven, successively with burning producer gas entrance trip valve with burns producer gas inlet adjustment valve and be connected, is respectively equipped with mechanical chain formula diffusion valve one and diffusion valve two between combustion air inlet trip valve and combustion air variable valve and between burning producer gas entrance trip valve and burning producer gas inlet adjustment valve.