CN114480756B - Gas heating method for iron-smelting blast furnace - Google Patents
Gas heating method for iron-smelting blast furnace Download PDFInfo
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- CN114480756B CN114480756B CN202210141338.3A CN202210141338A CN114480756B CN 114480756 B CN114480756 B CN 114480756B CN 202210141338 A CN202210141338 A CN 202210141338A CN 114480756 B CN114480756 B CN 114480756B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/06—Making pig-iron in the blast furnace using top gas in the blast furnace process
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H3/00—Air heaters
- F24H3/006—Air heaters using fluid fuel
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Abstract
The invention discloses a gas heating method for an ironmaking blast furnace, wherein furnace gas and combustion air are fed into the furnace of the gas heating furnace to burn and heat checker bricks, the furnace gas and the combustion air are stopped to be fed into the choke plug, the space in an inerting furnace is purged, normal-temperature metallurgical pressurized gas is fed into the inlet of the gas heating furnace, the gas is heated through heat transfer of the checker bricks of the gas heating furnace, and is fed out from the outlet of the gas heating furnace, mixed with part of cold gas in a gas mixing chamber before entering the blast furnace according to a certain proportion, and then blown into the blast furnace, and when the temperature of the mixed gas does not meet the requirement of a user, the gas is fed into the gas heating furnace after other furnace burning is replaced; and (3) discharging residual gas in the replaced gas heating furnace to a low-pressure gas main pipe, purging the space in the inerting furnace, and switching the discharging direction of the residual gas to a flue main pipe, wherein the gas heating furnace is subjected to next-round furnace burning and sequentially circulates.
Description
Technical Field
The invention belongs to the technical field of blast furnace ironmaking, and particularly relates to a gas heating system and a heating technology.
Background
The hot air heating furnace for traditional blast furnace ironmaking adopts a hot air furnace heating mode, the heating medium is mostly air containing 21% of oxygen, the baking gas and the combustion air are utilized to burn the checker bricks in the heating furnace in the combustion chamber of the hot air furnace, when the temperature of the checker bricks is raised to 1250-1400 ℃, the baking operation is stopped, cold air is blown in from a cold air inlet of the hot air furnace, the blown cold air is changed into hot air after heat transfer with the high-temperature checker bricks in the hot air furnace, then the hot air is mixed with the cold air in a certain proportion at a mixing valve, the mixed air reaches the temperature required by a user, and finally the hot air is fed into the blast furnace; when the temperature of the mixed air does not meet the requirements of users, replacing other hot air furnaces after the burning of the hot air furnaces to send hot air, and carrying out the next round of burning flow of the hot air furnaces after the air supply is finished, and sequentially circulating.
In order to reduce the carbon consumption of the blast furnace, the coal gas needs to be blown into the blast furnace after being heated, most of the existing coal gas heating furnaces are tubular heating furnaces or electric heating furnaces, the heating temperature is limited, the heating capacity is limited, the safety control difficulty in the heating process is high, and the occurrence of fire and explosion accidents can be caused by improper control.
Disclosure of Invention
The invention aims to provide a gas heating method for an ironmaking blast furnace, which aims to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions:
gas heating method for iron-smelting blast furnaceAfter the gas heating furnace burns, inert gas is introduced to expel the waste gas from the flue to O at the flue opening 2 After CO is lower than 1%, introducing metallurgical normal-temperature pressurized gas into an inlet of a gas heating furnace, heating and then delivering the gas from an outlet, mixing the heated pressurized gas with cold gas in a gas mixing chamber according to a certain proportion before entering the blast furnace to obtain mixed gas with 1200-1300 ℃, then injecting the mixed gas into the blast furnace, and replacing the gas heating furnace after the temperature of the mixed gas is lower than 1200 ℃ for delivering the gas after other burning furnaces. Closing an inlet valve and an outlet valve of the gas heating furnace after gas supply is finished, opening a residual gas recovery valve in the furnace, discharging residual high-pressure gas in the furnace to a low-pressure gas main pipe, introducing inert gas after the pressure in the furnace is reduced to the pressure of the low-pressure gas main pipe, continuously driving the low-pressure residual gas to the low-pressure gas main pipe, and leading the low-pressure residual gas to the O at a smoke gate 2 The CO is lower than 10 percent, a purging gas diffusing valve is opened, a residual gas recycling valve is closed, residual gas in the furnace is continuously blown to a gas diffusing tower to be combusted and then is discharged until O is arranged at a smoke flue opening 2 And the CO is lower than 1%, the purging operation is completed, a flue valve is opened, and the gas heating furnace carries out the next burning flow and circulates in turn.
The heating process comprises the following steps:
s1, a mode that the burning furnace gas enters a gas heating furnace is adopted: the furnace gas passes through a furnace gas regulating valve, a quick-cut valve and a double-seal gate valve and then enters a furnace burner. And a nitrogen purging air seal valve is arranged between the quick-cut valve and the double-seal gate valve. And during the choke plug and the coal gas feeding, the valve is filled with nitrogen and is sealed with pressure maintaining gas.
S2, a mode that combustion air of the burning furnace enters a gas heating furnace: the combustion air enters the gas heater through the combustion air regulating valve, the quick-cut valve and the double-seal gate valve, a nitrogen purging gas seal valve is arranged between the quick-cut valve and the double-seal gate valve, and nitrogen filling and pressure maintaining gas seal are carried out between the valves during the process of choke plug and gas feeding.
S3, furnace burning operation: before the furnace is burned, the flue valve is opened, combustion air of the furnace and a double-seal gate valve of gas of the furnace are simultaneously opened, the respective valves are opened to purge, the gas loop of the burner is purged with nitrogen, the vault is purged with nitrogen, and after 5 seconds, the flue is opened with O 2 After the CO is lower than 1%, all the purging nitrogen is closed, the combustion air quick-cutting valve and the combustion gas quick-cutting valve of the combustion furnace are opened, the combustion gas and the combustion air regulating valve start to act, and the combustion air and the gas enter the gas heating furnace according to a certain proportion to burn, so as to heat the checker bricks in the heating furnace.
S4, furnace burning and choke plug operation: heating the lattice bricks and the baking tops in the furnace to a certain temperature to stop burning the furnace, and finishing the furnace-smoldering operation according to the following sequence: firstly, closing a combustion air regulating valve and a quick-cut valve, opening a gas regulating valve and a gas cutting valve, opening a purging valve between gas and an air valve to purge for 10-15 seconds, simultaneously opening an air loop of a burner and a purging valve of the gas loop for 10-15 seconds, opening a nitrogen purging valve of an exhaust gas pipeline and a purging valve of a refrigerant gas pipeline for 10-15 seconds, and opening O at a flue position 2 And the CO content is lower than 1%, the double sealing gate valves of the air and the gas of the burning furnace are closed, and the nitrogen purging valve between the air valve and the gas valve of the burning furnace is closed after 3 seconds. And finally closing the flue valve.
S5, choke plug transfer gas operation: confirming that gas-feeding heating furnace flue, combustor inlet and vault oxygen meter display O 2 The content is lower than 1%, the cold gas equalizing valve is opened for 20% of opening, the equalizing valve is opened to 50% when the pressure difference between the inside and the outside of the furnace is lower than 80Kpa, the equalizing valve is opened to 100% when the pressure difference between the inside and the outside of the furnace is lower than 50Kpa, the equalizing in the furnace is completed, the cold gas cut-off valve is opened after the pressure difference between the inside and the outside of the furnace is lower than 5Kpa, nitrogen is purged between the cold gas cut-off valve and the cold gas double-seal gate valve, the cold gas double-seal gate valve is opened, and the hot air valve is opened to start feeding hot gas into the furnace.
S6, the operation of transferring the gas into a choke plug is that the gas-transferring heating furnace 2 is closed, the gas-transferring hot air valve 1 is closed, and the purging sealing nitrogen between the hot air valve 1 and the valve 2 is opened. And closing a cold gas cut-off valve of the gas feeding heating furnace, closing a cold gas double-seal gate valve of the gas feeding heating furnace, and opening a nitrogen purging gas seal valve between the valves. And finishing the operation of transferring the gas into a choke plug.
S7, decompression operation after furnace closing: and opening an exhaust valve of the gas heating furnace, and opening an exhaust regulating valve by 20 percent, wherein high-pressure gas in the gas heating furnace is discharged through an exhaust pipeline, and the exhaust pipeline is connected to a low-pressure gas pipe network to realize recycling of the high-pressure gas in the furnace.
S8, purging operation after furnace closing: after the pressure in the gas heating furnace is released to the pressure of the low-pressure pipe network, nitrogen is purged between combustion air of a burner of the gas heating furnace and a gas valve of the gas heating furnace, double sealing gate valves of the combustion air and the gas of the gas heating furnace are opened, nitrogen purging valves of air and the gas loop of the gas burner are opened, a vault is opened to purge nitrogen, a refrigerant gas pipeline purging valve is opened, residual gas in the furnace is blown to a low-pressure gas pipeline until O at a smoke gate is reached 2 The CO content is lower than 10%, the purging gas diffusing valve is opened, the residual gas recycling valve is closed, the residual gas in the furnace is continuously blown to the gas diffusing tower to be combusted and then is discharged until O is arranged at the smoke gate 2 The CO is lower than 1%, the flue valve is opened, the purge gas diffusion valve is closed until all the measuring points O of the flue 2 And after the CO is lower than 1%, the purging operation is finished, and the purging operation before the smoldering furnace is turned into the burning furnace is finished.
S9, furnace burning operation after purging operation is completed: and closing all the purging nitrogen, opening a combustion-supporting air quick-cutting valve and a combustion-supporting gas quick-cutting valve of the combustion furnace, starting the combustion-supporting gas and a combustion-supporting air regulating valve to act, enabling the combustion-supporting air and the gas to enter the gas heating furnace according to a certain proportion for combustion, heating the checker bricks in the heating furnace, and starting the operations of choke plug, gas feeding, choke plug and combustion furnace of the other round.
Compared with the prior art, the invention has the beneficial effects that:
the invention overcomes the inflammable and explosive characteristics of the gas, and realizes that the gas is heated to more than 1200 ℃ on the premise of safety and reliability, so that the gas heating furnace has the capability of continuously heating the gas.
Drawings
FIG. 1 is a schematic flow chart of the present invention;
FIG. 2 is a process flow diagram of a single gas heater of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides the following technical embodiments:
referring to fig. 1 to 2, a gas heating method for an ironmaking blast furnace,
a gas heating method for iron-smelting blast furnace includes such steps as burning in gas furnace, introducing inert gas to expel waste gas from flue to O at flue mouth 2 After CO is lower than 1%, introducing metallurgical normal-temperature pressurized gas into an inlet of a gas heating furnace, heating and then delivering the gas from an outlet, mixing the heated pressurized gas with cold gas in a gas mixing chamber according to a certain proportion before entering the blast furnace to obtain mixed gas with 1200-1300 ℃, then injecting the mixed gas into the blast furnace, and replacing the gas heating furnace after the temperature of the mixed gas is lower than 1200 ℃ for delivering the gas after other burning furnaces. Closing an inlet valve and an outlet valve of the gas heating furnace after gas supply is finished, opening a residual gas recovery valve in the furnace, discharging residual high-pressure gas in the furnace to a low-pressure gas main pipe, introducing inert gas after the pressure in the furnace is reduced to the pressure of the low-pressure gas main pipe, continuously driving the low-pressure residual gas to the low-pressure gas main pipe, and leading the low-pressure residual gas to the O at a smoke gate 2 The CO is lower than 10 percent, a purging gas diffusing valve is opened, a residual gas recycling valve is closed, residual gas in the furnace is continuously blown to a gas diffusing tower to be combusted and then is discharged until O is arranged at a smoke flue opening 2 And the CO is lower than 1%, the purging operation is completed, a flue valve is opened, and the gas heating furnace carries out the next burning flow and circulates in turn.
The heating process comprises the following steps:
s1, a mode that the burning furnace gas enters a gas heating furnace is adopted: the furnace gas passes through a furnace gas regulating valve, a quick-cut valve and a double-seal gate valve and then enters a furnace burner. And a nitrogen purging air seal valve is arranged between the quick-cut valve and the double-seal gate valve. And during the choke plug and the coal gas feeding, the valve is filled with nitrogen and is sealed with pressure maintaining gas.
S2, a mode that combustion air of the burning furnace enters a gas heating furnace: the combustion air enters the gas heater through the combustion air regulating valve, the quick-cut valve and the double-seal gate valve, a nitrogen purging gas seal valve is arranged between the quick-cut valve and the double-seal gate valve, and nitrogen filling and pressure maintaining gas seal are carried out between the valves during the process of choke plug and gas feeding.
S3, furnace burning operation: before the furnace is burned, the flue valve is opened, combustion air of the furnace and a double-seal gate valve of gas of the furnace are simultaneously opened, the respective valves are opened to purge, the gas loop of the burner is purged with nitrogen, the vault is purged with nitrogen, and after 5 seconds, the flue is opened with O 2 After the CO is lower than 1%, all the purging nitrogen is closed, the combustion air quick-cutting valve and the combustion gas quick-cutting valve of the combustion furnace are opened, the combustion gas and the combustion air regulating valve start to act, and the combustion air and the gas enter the gas heating furnace according to a certain proportion to burn, so as to heat the checker bricks in the heating furnace.
S4, furnace burning and choke plug operation: heating the lattice bricks and the baking tops in the furnace to a certain temperature to stop burning the furnace, and finishing the furnace-smoldering operation according to the following sequence: firstly, closing a combustion air regulating valve and a quick-cut valve, opening a gas regulating valve and a gas cutting valve, opening a purging valve between gas and an air valve to purge for 10-15 seconds, simultaneously opening an air loop of a burner and a purging valve of the gas loop for 10-15 seconds, opening a nitrogen purging valve of an exhaust gas pipeline and a purging valve of a refrigerant gas pipeline for 10-15 seconds, and opening O at a flue position 2 And the CO content is lower than 1%, the double sealing gate valves of the air and the gas of the burning furnace are closed, and the nitrogen purging valve between the air valve and the gas valve of the burning furnace is closed after 3 seconds. And finally closing the flue valve.
S5, choke plug transfer gas operation: confirming that the O2 content in a flue of the gas-feeding heating furnace, a combustor inlet and a vault oxygen meter is lower than 1%, opening a cold gas equalizing valve by 20%, opening the equalizing valve to 50% when the pressure difference between the inside and the outside of the furnace is lower than 80Kpa, opening the equalizing valve to 100% when the pressure difference between the inside and the outside of the furnace is lower than 50Kpa, finishing the pressure equalization in the furnace, opening a cold gas cut-off valve after the pressure difference between the inside and the outside of the furnace is lower than 5Kpa, closing a nitrogen purging valve between the cold gas cut-off valve and a cold gas double-seal gate valve, opening the cold gas double-seal gate valve, and opening a hot air valve to start feeding hot gas into the furnace.
S6, the operation of transferring the gas into a choke plug is that the gas-feeding heating furnace is closed, the gas-feeding hot air valve is closed, and the purging sealing nitrogen between the hot air valve 1 and the valve 2 is opened. And closing a cold gas cut-off valve of the gas feeding heating furnace, closing a cold gas double-seal gate valve of the gas feeding heating furnace, and opening a nitrogen purging gas seal valve between the valves. And finishing the operation of transferring the gas into a choke plug.
S7, decompression operation after furnace closing: and opening an exhaust valve of the gas heating furnace, and opening an exhaust regulating valve by 20 percent, wherein high-pressure gas in the gas heating furnace is discharged through an exhaust pipeline, and the exhaust pipeline is connected to a low-pressure gas pipe network to realize recycling of the high-pressure gas in the furnace.
S8, purging operation after furnace closing: after the pressure in the gas heating furnace is released to the pressure of the low-pressure pipe network, nitrogen is purged between combustion air of a burner of the gas heating furnace and a gas valve of the gas heating furnace, double sealing gate valves of the combustion air and the gas of the gas heating furnace are opened, nitrogen purging valves at the circular paths of the air and the gas burner are opened, nitrogen is purged through a vault, a refrigerant gas pipeline purging valve is opened, residual gas in the furnace is blown to a low-pressure gas pipeline until O at a smoke gate is reached 2 The CO is lower than 10%, the purging gas diffusing valve is opened, the residual gas recycling valve is closed, the residual gas in the furnace is continuously blown to the gas diffusing tower to be combusted and then is discharged until the O at the smoke port 2 The CO is lower than 1%, the flue valve is opened, the purge gas diffusion valve is closed until all the measuring points O of the flue 2 After CO is lower than 1%, the wastegate valve W2, and the wastegate valve WR are simultaneously closed. And after O2 and CO in the flue are lower than 1%, the purging operation is completed, and the purging operation before smoldering and burning is completed.
S9, furnace burning operation after purging operation is completed: and closing all the purging nitrogen, opening a combustion-supporting air quick-cutting valve and a combustion-supporting gas quick-cutting valve of the combustion furnace, starting the combustion-supporting gas and a combustion-supporting air regulating valve to act, enabling the combustion-supporting air and the gas to enter the gas heating furnace according to a certain proportion for combustion, heating the checker bricks in the heating furnace, and starting the operations of choke plug, gas feeding, choke plug and combustion furnace of the other round.
Examples
In the middle repair of a blast furnace of 2500m eight steel in 9 2019, a 3-seat top combustion type gas heating furnace used by the blast furnace is synchronously modified, a low-pressure gas discharge channel of the gas heating furnace is arranged, a double hot air valve and a nitrogen sealing mechanism are arranged, and a safety control system is added with CO and O 2 After finishing the middle repair, the coke oven gas is blown into the gas heating furnace through the test, and the gas is successfully heated to the temperature through the gas heating furnaceAnd after 1100 ℃, the mixture is blown into a blast furnace.
In the process, firstly, a No. 1 gas heating furnace is used for blowing air, firstly, a flue valve of the No. 1 gas heating furnace is opened, the gas and the combustion air of the combustion furnace are introduced into the No. 1 gas heating furnace, the introduced gas and air are combusted in a combustion chamber of the No. 1 gas heating furnace, when the temperature of a vault of the No. 1 gas heating furnace reaches 1300 ℃, the combustion furnace is stopped, a No. 1 gas heating furnace system is opened for protecting nitrogen, the space in the furnace is purged and inerted by the nitrogen, and when the gas composition at a flue opening of the No. 1 gas heating furnace is detected, CO and O are displayed 2 When the concentration is reduced below 1%, a flue valve and a system security nitrogen are closed, a 1# cold gas equalizing valve is opened, when the internal pressure difference between a cold gas pipeline and a 1# gas heating furnace is smaller than 5KPa, a 1# cold gas valve is opened, coke oven gas is blown into an inlet of the 1# gas heating furnace, a 1# gas heating furnace hot blast valve 1 and a hot blast valve 2 are opened, the coke oven gas heated by the 1# gas heating furnace is blown into a blast furnace, the heated coke oven gas is firstly mixed with unheated coke oven gas in a gas mixing chamber before the heated gas enters the blast furnace, the temperature of the mixed gas is controlled to be 1100 ℃ by regulating and controlling the opening of a hot gas regulating valve at the front end of the gas mixing chamber, and the mixed gas is sprayed into the blast furnace from a wind gap. When the gas is fed into the No. 1 gas heating furnace for 63 minutes, the opening of a hot gas regulating valve at the front end of the gas mixing chamber reaches 100%, the temperature of mixed gas is 1093 ℃, furnace changing operation is carried out, after the combustion is completed, a cold gas equalizing valve of the No. 2 gas heating furnace with the vault temperature reaching 1300 ℃ is opened, when the difference between the internal pressure of a cold gas pipeline and the internal pressure of the No. 2 gas heating furnace is less than 5KPa, a No. 2 cold gas valve is opened, coke oven gas is blown into an inlet of the No. 2 gas heating furnace, a hot air valve 3 and a hot air valve 4 of the No. 2 gas heating furnace are opened, the coke oven gas heated by the No. 2 gas heating furnace is blown into a blast furnace, meanwhile, a hot air valve 1 and a hot air valve 2 of the No. 1 gas heating furnace are closed, a cold gas valve of the No. 1 is closed, a residual gas recovery valve of the No. 1 gas heating furnace is opened, residual gas in the No. 1 gas heating furnace is fed into a low-pressure gas pipeline, a No. 1 gas heating furnace system is opened, nitrogen is protected, when the concentration of CO and O2 at the measuring point at the No. 1 gas port is displayed at the position of the heating furnace is reduced to be less than 1%, the concentration of less than 1%, a flue valve of the No. 1 is opened, the residual gas valve of the No. 1 is closed, the No. 1 gas heating furnace is closed, the 1 gas heating furnace is blown into the system is repeatedly, and the combustion gas is blown into the system after the No. 1 gas heating furnace is cooled, and the gas is repeatedly cooled, and the gas is burned into the system, and the step is repeatedly cooled, and the furnace is cooled, and heated, and the furnace is heated, and the temperature is heatedThe operation steps of the gas heating furnace and the 3# gas heating furnace are consistent with the operation method of the 1# gas heating furnace, the 3# gas heating furnaces alternately convey heating gas to the blast furnace, and the continuous flow of conveying the heating gas to the blast furnace is realized after the middle repair.
The invention overcomes the inflammable and explosive characteristics of the gas, solves the problems of sealing a system for heating the gas by the gas heating furnace, discharging exhaust gas and residual gas, matching the functions of the gas heating furnace for heating the gas, and the like, and realizes the process flow of heating the high-pressure gas to more than 1000 ℃ by the gas heating furnace on the premise of safety and reliability, so that the gas heating furnace has the capability of continuously heating and blowing the pressurized gas.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is merely illustrative of the present invention and not restrictive, and other modifications and equivalents thereof may occur to those skilled in the art without departing from the spirit and scope of the present invention.
Claims (9)
1. A gas heating method for an ironmaking blast furnace is characterized in that: after the gas heating furnace burns, inert gas is introduced to expel waste gas from the flue to O at the flue opening 2 After the CO is lower than 1%Introducing metallurgical normal-temperature pressurized gas into an inlet of a gas heating furnace, heating and then delivering the gas from an outlet, mixing the heated pressurized gas with cold gas in a gas mixing chamber in a certain proportion before entering the blast furnace to obtain mixed gas with the temperature of 1200-1300 ℃, then injecting the mixed gas into the blast furnace, replacing the gas from the gas heating furnace after the other gas is burnt when the temperature of the mixed gas is lower than 1200 ℃, closing an inlet valve and an outlet valve of the gas heating furnace after the gas is completely fed, opening a residual gas recovery valve in the furnace, discharging residual high-pressure gas in the furnace to a low-pressure gas main pipe, introducing inert gas to continuously drive the low-pressure residual gas to the low-pressure gas main pipe until the pressure in the furnace is reduced to the pressure of the low-pressure gas pipe network, and introducing inert gas to O at a smoke gate 2 The CO is lower than 10 percent, a purging gas diffusing valve is opened, a residual gas recycling valve is closed, residual gas in the furnace is continuously blown to a gas diffusing tower to be combusted and then is discharged until O is arranged at a smoke flue opening 2 The CO is lower than 1%, the purging operation is completed, a flue valve is opened, and the gas heating furnace carries out the next burning flow and circulates in sequence; the method specifically comprises the following steps:
s1, a mode that the burning furnace gas enters a gas heating furnace is adopted: the furnace gas passes through a furnace gas regulating valve, a quick-cut valve and a double-seal gate valve and then enters a furnace burner; a nitrogen purging air seal valve is arranged between the quick-cut valve and the double-seal gate valve; during the choke plug and the coal gas feeding, the valves are filled with nitrogen and pressure maintaining gas seal;
s2, a mode that combustion air of the burning furnace enters a gas heating furnace: the combustion air enters an internal combustion device of the gas heating furnace after passing through a combustion air regulating valve, a quick-cut valve and a double-seal gate valve, a nitrogen purging gas seal valve is arranged between the quick-cut valve and the double-seal gate valve, and nitrogen filling and pressure maintaining gas seal are carried out between the valves during the process of choke plug and gas feeding;
s3, furnace burning operation: before the furnace is burned, the flue valve is opened, combustion air of the furnace and a double-seal gate valve of gas of the furnace are simultaneously opened, the respective valves are opened to purge, the gas loop of the burner is purged with nitrogen, the vault is purged with nitrogen, and after 5 seconds, the flue is opened with O 2 After the CO is lower than 1%, all the purging nitrogen is closed, the combustion air quick-cut valve of the combustion furnace and the combustion gas quick-cut valve of the combustion furnace are opened, the combustion gas and the combustion air regulating valve start to act, the combustion air,The gas enters a gas heating furnace according to a certain proportion for burning, and the lattice bricks in the heating furnace are heated;
s4, furnace burning and choke plug operation: heating the lattice bricks and the baking tops in the furnace to a certain temperature to stop burning the furnace, and finishing the furnace-smoldering operation according to the following sequence: firstly, closing a combustion air regulating valve and a quick-cut valve, opening a gas regulating valve and a gas cutting valve, opening a purging valve between gas and an air valve to purge for 10-15 seconds, simultaneously opening an air loop of a burner and a purging valve of the gas loop for 10-15 seconds, opening a nitrogen purging valve of an exhaust gas pipeline and a purging valve of a cold gas pipeline for 10-15 seconds, and opening O at a flue position 2 The CO content is lower than 1%, the double sealing gate valves of the air and the gas of the burning furnace are closed, and the nitrogen purging valve between the air valve and the gas valve of the burning furnace is closed after 3 seconds; finally closing the flue valve;
s5, choke plug transfer gas operation: confirming that gas-feeding heating furnace flue, combustor inlet and vault oxygen meter display O 2 The content is lower than 1%, the cold gas equalizing valve is opened for 20% of opening, the equalizing valve is opened to 50% when the pressure difference between the inside and the outside of the furnace is lower than 80Kpa, the equalizing valve is opened to 100% when the pressure difference between the inside and the outside of the furnace is lower than 50Kpa, the equalizing in the furnace is completed, the cold gas cut-off valve is opened after the pressure difference between the inside and the outside of the furnace is lower than 5Kpa, nitrogen is purged between the cold gas cut-off valve and the cold gas double-seal gate valve, the cold gas double-seal gate valve is opened, and the hot air valve is opened to start feeding hot gas into the furnace;
s6, performing gas feeding and choke plug operation, namely closing a hot air valve 2 and a hot air valve 1 on a connecting pipeline between a gas heating furnace for conveying gas and a blast furnace tuyere in the step S5, and opening purge sealing nitrogen between the hot air valve 1 and the hot air valve 2; closing a cold gas cut-off valve of the gas feeding heating furnace, closing a cold gas double-seal gate valve of the gas feeding heating furnace, and opening a nitrogen purging gas seal valve between the valves to finish the operation of converting the gas feeding into choke plug;
s7, decompression operation after furnace closing: opening an exhaust valve of the gas heating furnace, and opening an exhaust regulating valve by 20 percent, wherein high-pressure gas in the gas heating furnace is discharged through an exhaust pipeline which is connected to a low-pressure gas pipe network, so that the recycling of the high-pressure gas in the furnace is realized;
s8, purging operation after furnace closing: after the pressure in the gas heating furnace is released to the low-pressure pipe network force, the combustion is openedNitrogen is purged between combustion air of a burner and a gas valve of a combustion furnace, a double-seal gate valve of combustion air and combustion furnace gas is opened, a nitrogen purging valve at the loop of the air and gas burner is opened, a vault is opened to purge nitrogen, a purging valve of a cold gas pipeline is opened, and residual gas in the furnace is blown to a low-pressure gas pipeline until O at a smoke gate is reached 2 The CO content is lower than 10%, the purging gas diffusing valve is opened, the residual gas recycling valve is closed, the residual gas in the furnace is continuously blown to the gas diffusing tower to be combusted and then is discharged until O is arranged at the smoke gate 2 The CO is lower than 1%, the flue valve is opened, the purge gas bleeding valve is closed until all the measuring points O of the flue 2 After the CO is lower than 1%, the purging operation is completed, and the purging operation before the smoldering furnace is turned into the burning furnace is completed;
s9, furnace burning operation after purging operation is completed: and closing all the purging nitrogen, opening a combustion-supporting air quick-cutting valve and a combustion-supporting gas quick-cutting valve of the combustion furnace, starting the combustion-supporting gas and a combustion-supporting air regulating valve to act, enabling the combustion-supporting air and the gas to enter the gas heating furnace according to a certain proportion for combustion, heating the checker bricks in the heating furnace, and starting the operations of choke plug, gas feeding, choke plug and combustion furnace of the other round.
2. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: and S5, the hot gas outlet valves are all arranged in series of two hot gas valves, a nitrogen gas inlet pipeline is arranged between the valves, and when the hot gas valve is closed, nitrogen gas is introduced between the valves for security.
3. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: and S3, using two double-seal gate valves for the combustion-supporting air pipeline of the combustion furnace and two double-seal gate valves for the gas pipeline of the combustion furnace, wherein nitrogen purging and gas sealing are arranged between the valves.
4. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: the burner air and gas loop is provided with two nitrogen purges.
5. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: the vault of the gas heating furnace is provided with a nitrogen purge.
6. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: a gas recovery device is arranged for discharging the high-pressure gas remained in the choke plug of the gas-feeding heating furnace to a low-pressure gas pipe network.
7. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: introducing inert gas to drive the low-pressure residual gas to the low-pressure gas main pipe until reaching the smoke port O 2 The CO is lower than 10 percent, a purging gas diffusing valve is opened, a residual gas recycling valve is closed, residual gas in the furnace is continuously blown to a gas diffusing tower to be combusted and then is discharged until O is arranged at a smoke flue opening 2 CO is lower than 1%.
8. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: 2-3 CO and O are arranged in each gas heating furnace flue and flue header pipe 2 And (5) monitoring.
9. The gas heating method for an ironmaking blast furnace according to claim 1, wherein: CO monitoring is arranged at the inlet of the combustion air pipeline of each gas heating furnace, and O is arranged at the gas inlet of each gas heating furnace 2 And (5) monitoring.
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