CN115058548B - A supersonic hydrogen injection system and control method based on Raoult nozzle - Google Patents

Abstract

A supersonic hydrogen injection system based on a Raoult nozzle and a control method thereof are provided, wherein the Raoult nozzle is used for injecting hydrogen into a blast furnace in a supersonic mode, the hydrogen is subjected to diffusion combustion in an oxygen-enriched hot air environment in a turbulent flame mode, the reaction rate is low, the local heat release is less, the heat flow distribution is uniform, the combustion peak temperature is low, compared with the traditional straight pipe hydrogen injection local high-temperature combustion, the reaction is carried out in a large area, even the whole blowpipe, the flame front disappears, and the thermal state burning loss of the local heat release of the hydrogen combustion to the outlet of a spray gun can be effectively avoided; meanwhile, a protective gas pipeline is assisted outside the Raoult spray pipe, and inert gases such as nitrogen are introduced, so that the rapid combustion of hydrogen in a local area of an outlet of the spray gun is further avoided. The invention is suitable for the blast furnace hydrogen injection iron making process, can effectively prolong the service life of the hydrogen spray gun, reduce the spray gun replacement times in the blast furnace hydrogen injection process, and promote the popularization and application of the blast furnace hydrogen-rich smelting technology.

Description

A supersonic hydrogen injection system and control method based on Raoult nozzle

technical field

The invention belongs to the technical field of hydrogen injection for blast furnace ironmaking, and in particular relates to a supersonic hydrogen injection system and a control method based on a Raoult nozzle.

Background technique

Against the background of climate change and energy transition, all countries attach great importance to the development and utilization of carbon-free and low-carbon energy, and the metallurgical process technology transformation centered on reducing carbon footprint and carbon emission has attracted increasing attention from the iron and steel industry. Hydrogen energy is regarded as the clean energy with the most development potential in the 21st century. Hydrogen is used to replace some carbonaceous raw materials (coke, coal powder) as the fuel and metal oxide reducing agent in the process of blast furnace smelting molten pig iron, which is different from traditional carbon metallurgy. Compared with the reaction product, the greenhouse gas _CO2 is transformed into water, which fundamentally reduces the carbon emissions of the iron and steel production process.

At present, the hydrogen metallurgy technology in the iron and steel smelting process is mainly the blast furnace hydrogen injection, that is, the ironmaking method that hydrogen or hydrogen-rich gas is blown into the blast furnace through the hydrogen injection device at the tuyere or the hydrogen injection device at the lower part of the furnace shaft. However, hydrogen is an extremely flammable In the highly oxidative atmosphere of the hot air direct blowing pipe, the hydrogen gas at the nozzle outlet will burn rapidly and release a large amount of heat, which will cause the nozzle area of the hydrogen nozzle to be easily burned. The high concentration of hydrogen gas makes hydrogen deflagration prone to occur in this area, which seriously affects the safe and stable operation of the blast furnace hydrogen injection system.

Therefore, how to improve the existing blast furnace hydrogen injection system and combine the corresponding hydrogen injection control method to ensure that the hydrogen spray gun is not easy to burn out and maintain a long service life in the high-temperature and high-oxidation tuyere direct blow pipe and the swirling area is the current hydrogen-rich smelting of the blast furnace. Key technical problems that need to be solved urgently.

Contents of the invention

In order to solve the above problems, the present invention proposes a supersonic hydrogen injection system and control method based on the Raoult nozzle. Based on the Raoult nozzle, the hydrogen is imported into the blast furnace from the outlet of the spray gun in the form of supersonic speed. Volume combustion or diffuse combustion occurs in the form of turbulent flames in the environment, which is characterized by low reaction rate, less local heat release, uniform heat flow distribution, low combustion peak temperature and minimal noise. Compared with high-temperature combustion, the reaction is carried out in a large area, or even the entire straight blowpipe, and the flame front disappears, which can effectively avoid the excessive concentration of hydrogen in a local area to form a flame front that produces large radiant heat and convective heat transfer, resulting in burning of the hydrogen spray gun; According to the actual smelting conditions of the blast furnace, and according to the needs of the actual smelting conditions, when the set injection flow rate of hydrogen is too small to achieve supersonic speed, nitrogen is added to the main blowing jet to maintain a sufficient front end of the Raoul nozzle. Gas pressure; at the same time, a shielding gas nozzle is provided outside the Raoult nozzle, and nitrogen and other inert gases are introduced. On the one hand, the oxygen concentration in the exit area of the spray gun is reduced to achieve the defire effect of the hydrogen jet. At the same time, the shielding gas can prolong the core of the supersonic jet. The length of the zone further expands the combustion range of hydrogen.

Technical solution of the present invention is as follows:

A supersonic hydrogen injection system based on a Raoult nozzle, characterized in that it includes a Raoult nozzle body and a shielding gas nozzle body sleeved thereon, the Raoult nozzle body An annular gap is left between the outer surface of the outer surface of the protective gas nozzle body and the inner surface of the protective gas nozzle body to form a protective gas passage, and the injection port of the Raoul nozzle body is connected to the inner surface of the protective gas nozzle body. The injection annular seam port has a coaxial relationship, and the inlet end of the Raoul nozzle body is respectively connected to the output end of the hydrogen control valve group and the output end of the main blowing inert gas control valve group through a three-way pipe. The inlet end of the pipe body is connected to the output end of the protective gas control valve group, the input end of the protective gas control valve group and the input end of the main inert gas control valve group are connected to the inert gas source, and the hydrogen control valve group input end is connected to the hydrogen gas source. The inlet end of the Raoul nozzle body is provided with a pipeline gas pressure sensor to control the flow velocity of the supersonic jet formed at the injection port.

The inert gas is nitrogen and/or argon, and the volume fraction of oxygen in the inert gas is <5%.

On the one hand, the protective gas jet sprayed at the annular seam port reduces the oxygen concentration in the injection port area to achieve the defire effect of the hydrogen jet, and on the other hand, the length of the core area of the supersonic jet is extended to expand the combustion range of hydrogen in the hearth of the ironmaking blast furnace .

The pipeline gas pressure sensor, the main blowing inert gas control valve group, the hydrogen gas control valve group and the protective gas control valve group are respectively connected to the host computer, so that the hydrogen gas and the main blowing inert gas flow together to form a supersonic jet at the injection port , so that the shielding gas reaches a preset flow rate and flow rate at the injection annular seam port.

The speed of the supersonic jet is Mach 1-2.

The blowing port of the Raoul nozzle tube body is inwardly divided into expansion section, throat section and contraction section in turn, the inlet diameter of the contraction section is 58mm ± 10%, and the half-cone angle is 22 degrees ± 10%. The diameter of the throat section is 29mm±10%, the length is 8mm±10%, the outlet diameter of the expansion section is 31mm±10%, and the half-cone angle is 5°±10%.

The application of a supersonic hydrogen injection system based on a Raoult nozzle in blast furnace ironmaking is used to inject hydrogen from the tuyere of the blast furnace into the furnace chamber of the blast furnace.

A control method for a supersonic hydrogen injection system based on a Raoul nozzle, characterized in that it includes the following modes:

Non-hydrogen injection mode: when the injection system is not injected with hydrogen during the blast furnace smelting process, both the Raoul nozzle and the shielding gas nozzle are fed with inert gas;

Hydrogen injection mode: When hydrogen injection starts, the set hydrogen injection flow rate is input to the control system, and the flow controller in the hydrogen control valve group automatically adjusts the valve opening to adjust the hydrogen injection flow rate to the set flow rate. Nozzle still sprays inert gas;

Real-time monitoring of pipeline gas pressure, when the gas pressure at the front end of the Raoult nozzle is greater than or equal to the critical pressure of the Mach number set by the Raoult nozzle, the existing operation remains unchanged; when the gas pressure at the front end of the Raoult nozzle is less than the set Mach When the critical pressure is reached, the control system will automatically open the quick cut-off valve of the main blowing inert gas pipeline control valve group, and at the same time adjust the flow controller in the main blowing inert gas control valve group to adjust the valve opening to the gas pressure at the front end of the Raoult nozzle equal to Set the Mach number critical pressure.

In the non-hydrogen injection mode, the inert gas flow range of the Raoult nozzle is 500-2000Nm ³ /h, and the inert gas flow range of the protective gas nozzle is 200-800Nm ³ /h;

In the hydrogen injection mode, the hydrogen gas flow range of the Raoult nozzle is 0-2500Nm ³ /h, the inert gas flow range of the Raoult nozzle is 0-1500Nm ³ /h, and the inert gas flow range of the protective gas nozzle is 200～800Nm ³ /h.

The technical effect of the present invention is as follows: the present invention is a supersonic hydrogen injection system and control method based on the Raoult nozzle. Diffused combustion occurs in the form of turbulent flames in a hot air environment, with low reaction rate, less local heat release, uniform heat flow distribution, and low combustion peak temperature. When the blowpipe is carried out, the flame front disappears, which can effectively avoid the thermal burning of the spray gun outlet caused by the partial heat release of hydrogen combustion; at the same time, a protective gas pipeline is provided outside the Raoul nozzle, and nitrogen and other inert gases are introduced to further prevent hydrogen from being sprayed in the spray gun. The local area of the outlet burns rapidly. The invention is applicable to the blast furnace hydrogen injection ironmaking process, can effectively improve the service life of the hydrogen spray gun, reduce the replacement times of the spray gun during the hydrogen injection process of the blast furnace, and promote the popularization and application of the hydrogen-enriched smelting technology of the blast furnace.

Description of drawings

Fig. 1 is a structural schematic diagram of a supersonic hydrogen injection system based on a Raoult nozzle for implementing the present invention.

Reference signs are listed as follows: 1-hydrogen gas source; 2-inert gas source (including nitrogen and/or argon, oxygen volume fraction in inert gas<5%); 3-hydrogen control valve group; 4-main blowing Inert gas control valve group; 5-shielding gas control valve group; 6-tee pipe; 7-pipeline gas pressure sensor; 8-gas inlet of Raoul nozzle; 9-gas inlet of shielding gas nozzle; 10-Raoul Seoul nozzle; 11-shielding gas nozzle.

Detailed ways

The present invention is described below in conjunction with accompanying drawing (Fig. 1) and embodiment.

Fig. 1 is a structural schematic diagram of a supersonic hydrogen injection system based on a Raoult nozzle for implementing the present invention. With reference to Fig. 1, a kind of supersonic hydrogen injection system based on Raoult nozzle, comprises Raoult nozzle 10 pipe body and protective gas nozzle 11 pipe body socketed thereon, said Raoult nozzle An annular gap is left between the outer surface of the nozzle body and the inner surface of the shielding gas nozzle body to form a shielding gas passage, and the injection port of the Raoul nozzle body is connected to the shielding gas injection port. The injection annular seam port of the pipe body has a coaxial relationship, and the inlet end of the Raoul nozzle pipe body is respectively connected to the output end of the hydrogen control valve group 3 and the output of the main blowing inert gas control valve group 4 through a three-way pipe 6 end, the inlet end of the shielding gas nozzle body (through the gas inlet 9 of the shielding gas nozzle) is connected to the output end of the shielding gas control valve group 5, the input end of the shielding gas control valve group 5 and the main blowing inert gas control valve group 4 The input ends are all connected to the inert gas source 2, and the input end of the hydrogen control valve group 3 is connected to the hydrogen gas source 1, and the inlet end of the Raoul nozzle body (through the Raoul nozzle gas inlet 8) is provided with a pipeline The gas pressure sensor 7 is used to control the flow velocity of the supersonic jet formed by the injection port.

The inert gas is nitrogen and/or argon, and the volume fraction of oxygen in the inert gas is <5%. On the one hand, the protective gas jet sprayed at the annular seam port reduces the oxygen concentration in the injection port area to achieve the defire effect of the hydrogen jet, and on the other hand, the length of the core area of the supersonic jet is extended to expand the combustion range of hydrogen in the hearth of the ironmaking blast furnace . The pipeline gas pressure sensor 7, the main blowing inert gas control valve group 4, the hydrogen gas control valve group 3 and the protective gas control valve group 5 are respectively connected to the host computer, so that the hydrogen gas and the main blowing inert gas flow together and flow at the injection port. A supersonic jet flow is formed, so that the shielding gas reaches a preset flow rate and velocity at the injection annular seam port. The speed of the supersonic jet is Mach 1-2. The blowing ports of the Raoul nozzle 10 body are sequentially inwardly divided into expansion section, throat section and contraction section, the inlet diameter of the contraction section is 58 mm ± 10%, and the half-cone angle is 22 degrees ± 10%. , the diameter of the throat section is 29mm±10%, the length is 8mm±10%, the outlet diameter of the expansion section is 31mm±10%, and the half-cone angle is 5°±10%.

The application of a supersonic hydrogen injection system based on a Raoult nozzle in blast furnace ironmaking is used to inject hydrogen from the tuyere of the blast furnace into the furnace chamber of the blast furnace.

A control method for a supersonic hydrogen injection system based on a Raoult nozzle, characterized in that it includes the following modes: non-hydrogen injection mode: when the hydrogen injection system is not injected during the blast furnace smelting process, the Raoult nozzle and The protective gas nozzles are all fed with inert gas; hydrogen injection mode: when the hydrogen injection starts, the set hydrogen injection flow rate is input to the control system, and the flow controller in the hydrogen control valve group automatically adjusts the valve opening, and the hydrogen injection The blowing flow rate is adjusted to the set flow rate, and the protective gas nozzle is still blowing inert gas; the gas pressure of the pipeline is monitored in real time, and when the gas pressure at the front end of the Raoult nozzle is greater than or equal to the critical pressure of the Mach number set by the Raoult nozzle, the current The operation remains unchanged; when the gas pressure at the front end of the Raoult nozzle is lower than the set Mach number critical pressure, the control system automatically opens the quick cut-off valve of the main blowing inert gas pipeline control valve group, and at the same time adjusts the main blowing inert gas control valve group. The flow controller is used to adjust the opening of the valve until the gas pressure at the front end of the Raoul nozzle is equal to the set Mach number critical pressure.

In the non-hydrogen injection mode, the inert gas flow range of the Raoult nozzle is 500-2000Nm ³ /h, and the inert gas flow range of the shielding gas nozzle is 200-800Nm ³ /h; in the hydrogen injection mode, the Raoult nozzle hydrogen The gas flow range is 0-2500Nm ³ /h, the Raoult nozzle inert gas flow range is 0-1500Nm ³ /h, and the protective gas nozzle inert gas flow range is 200-800Nm ³ /h.

A supersonic hydrogen injection system based on a Raoul nozzle, the system includes an injection device, a gas supply system and a control system.

The blowing device is composed of a Raoult nozzle 10 and a shielding gas nozzle 11 .

The gas supply system includes a hydrogen gas source 1, an inert gas source 2, a hydrogen pipeline and a control valve group 3, a main inert gas blowing pipeline and a control valve group 4, a protective gas pipeline and a control valve group 5.

The control system includes a pipeline gas pipeline gas pressure sensor 7 and a host computer.

A supersonic hydrogen injection system based on a Raoult nozzle. The Raoult supersonic spray gun is composed of an expansion section, a throat section and a contraction section. A sonic jet; an annular gap is left between the shielding gas nozzle and the Raoul nozzle to form a shielding gas channel, and the Raoul nozzle and the shielding gas nozzle have a coaxial relationship.

The hydrogen source 1 is connected to the hydrogen control valve group 3 through a pipeline, the inert gas source 2 is connected to the main inert gas control valve group 4 through a pipeline, and then the hydrogen gas and the main inert gas are combined by a three-way pipeline 6 and then connected to the pull The Ur nozzle gas inlet 8 should also be equipped with a pipeline gas temperature and pressure sensor 7 on its tee pipeline gas output end pipeline.

The protective gas source 2 is connected to the protective gas control valve group 5 through a pipeline, and then connected to the gas inlet 9 of the protective gas nozzle of the blowing device through a pipeline.

The valve group should include a pneumatic quick shut-off valve, a manual quick shut-off valve, and a mass flow controller. The valve groups 3, 4, 5 and the pipeline gas pressure sensor 7 are connected with the host computer through data lines.

The control method of the supersonic hydrogen injection system based on the Raoul nozzle specifically includes the following modes:

Non-hydrogen injection mode: When the injection system is not injected with hydrogen during the blast furnace smelting process, both the Raoul nozzle and the protective gas nozzle are fed with inert gas.

Hydrogen injection mode: When hydrogen injection starts, the set hydrogen injection flow rate is input to the control system, and the flow controller in the hydrogen control valve group automatically adjusts the valve opening to adjust the hydrogen injection flow rate to the set flow rate. The nozzle is still spraying inert gas.

Real-time monitoring of pipeline gas pressure, when the gas pressure at the front end of the Raoult nozzle is greater than or equal to the critical pressure of the Mach number set by the Raoult nozzle, the existing operation remains unchanged; when the gas pressure at the front end of the Raoult nozzle is less than the set Mach When the critical pressure is reached, the control system will automatically open the quick cut-off valve of the main blowing inert gas pipeline control valve group, and at the same time adjust the flow controller in the main blowing inert gas control valve group to adjust the valve opening to the gas pressure at the front end of the Raoult nozzle equal to Set the Mach number critical pressure.

The inert gas includes nitrogen and argon, the volume fraction of oxygen in the gas is less than 0.5%, and the Mach number range set by the Raoult nozzle is 1-2.

In the non-hydrogen injection mode, the inert gas flow ranges of the Raoult nozzle and the protective gas nozzle are 500-2000Nm ³ /h and 200-800Nm ³ /h respectively. In the hydrogen injection mode, the hydrogen gas flow range of the Raoult nozzle is 0-2500Nm3/h, and the inert gas flow range of the Raoult nozzle and the shielding gas nozzle are ^0-1500Nm3 /h and ^200-800Nm3 /h respectively .

Example 1: The present invention is applied in a ^1780m3 blast furnace to inject hydrogen. The blast furnace has 26 tuyeres in total, the daily output of molten iron is 4300t, and the hydrogen injection rate per ton of iron and hydrogen is ^200Nm3 /t. Corner insertion, the flow rate of a single hydrogen spray gun is 1380m ³ /h, and the Raoul nozzle design Mach number is 1.5.

The inlet diameter of the contracting section of the Raoul nozzle is 58.13mm, the length of the contracting section is 34.88mm, the semi-conical focus of the contracting section is 22.6 degrees, the diameter of the throat section is 29.06mm, the length of the throat section is 8mm, and the outlet diameter of the expanding section is 31.52 mm, the length of the expansion section is 14.04mm, the half-cone angle of the expansion section is 5 degrees, and the design inlet pressure is 0.367MPa when the Mach number reaches 1.5. The shielding gas nozzle has an inner diameter of 65mm and an outer diameter of 75mm.

When the hydrogen injection system is not injecting hydrogen during the blast furnace smelting process, the Raoult nozzle and the protective gas nozzle are fed with nitrogen, and the flow rates are 1000Nm ³ /h and 500Nm ³ /h respectively.

During the blast furnace smelting process, when the hydrogen injection flow rate is set to 1500Nm ³ /h, the flow controller in the hydrogen control valve group automatically adjusts the valve opening to adjust the hydrogen injection flow rate to the set flow rate, and the Raoul nozzle The gas pressure at the front end is 0.367MPa higher than the design inlet pressure, forming a supersonic hydrogen jet.

During the blast furnace smelting process, when the hydrogen injection flow rate is 500Nm ³ /h, the gas pressure at the front end of the Raoult nozzle is less than the design inlet pressure of 0.367MPa, the control system automatically opens the main blowing inert gas pipeline control valve group quick shut-off valve, and at the same time Adjust the flow controller in the main blowing inert gas control valve group, and adjust the opening of the valve until the gas pressure at the front end of the Raoult nozzle is equal to 0.367MPa.

The contents not described in detail in the description of the present invention belong to the prior art known to those skilled in the art. It is pointed out here that the above description is helpful for those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any equivalent replacement, modification and improvement and/or simplified implementation of the above descriptions without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. A supersonic hydrogen injection system based on the Raoul nozzle, characterized in that it comprises a Raoul nozzle body and a shielding gas nozzle body which is socketed thereon, the Raoul nozzle An annular gap is left between the outer surface of the pipe body and the inner surface of the shielding gas nozzle body to form a shielding gas channel, and the injection port of the Raoul nozzle body is connected to the shielding gas nozzle pipe. The injection annular seam port of the body has a coaxial relationship, and the inlet end of the Raoul nozzle body is respectively connected to the output end of the hydrogen control valve group and the output end of the main blowing inert gas control valve group through a three-way pipeline. The inlet end of the gas nozzle body is connected to the output end of the protective gas control valve group, the input end of the protective gas control valve group and the input end of the main blowing inert gas control valve group are connected to the inert gas source, and the input end of the hydrogen control valve group is connected to hydrogen gas. source, the inlet end of the Raoul nozzle tube body is provided with a pipeline gas pressure sensor to control the flow velocity of the supersonic jet formed by the injection port; On the one hand, the protective gas jet sprayed at the annular seam port reduces the oxygen concentration in the injection port area to achieve the defire effect of the hydrogen jet, and on the other hand, the length of the core area of the supersonic jet is extended to expand the combustion range of hydrogen in the hearth of the ironmaking blast furnace ; The pipeline gas pressure sensor, the main blowing inert gas control valve group, the hydrogen gas control valve group and the protective gas control valve group are respectively connected to the host computer, so that the hydrogen gas and the main blowing inert gas flow together to form a supersonic jet at the injection port , so that the shielding gas reaches a preset flow rate and flow rate at the injection annular seam port; The blowing port of the Raoul nozzle tube body is inwardly divided into expansion section, throat section and contraction section in turn, the inlet diameter of the contraction section is 58mm ± 10%, and the half-cone angle is 22 degrees ± 10%. The diameter of the throat section is 29mm±10%, the length is 8mm±10%, the outlet diameter of the expansion section is 31mm±10%, and the half-cone angle is 5°±10%. 2. The supersonic hydrogen injection system based on Raoult nozzle according to claim 1, wherein said inert gas adopts nitrogen and/or argon, and oxygen volume fraction＜5% in said inert gas . 3 . The supersonic hydrogen injection system based on the Raoult nozzle according to claim 1 , wherein the speed of the supersonic jet is Mach 1-2. 4 . 4. The application of a supersonic hydrogen injection system based on a Raoult nozzle as claimed in any one of claims 1-3 in blast furnace ironmaking, which is used to inject hydrogen from the tuyere of the blast furnace into the hearth of the blast furnace. 5. A method for controlling the supersonic hydrogen injection system based on the Raoul nozzle as claimed in any one of claims 1-3, characterized in that it comprises the following modes: Non-hydrogen injection mode: when the injection system is not injected with hydrogen during the blast furnace smelting process, both the Raoul nozzle and the shielding gas nozzle are fed with inert gas; Hydrogen injection mode: When hydrogen injection starts, the set hydrogen injection flow rate is input to the control system, and the flow controller in the hydrogen control valve group automatically adjusts the valve opening to adjust the hydrogen injection flow rate to the set flow rate. Nozzle still sprays inert gas; Real-time monitoring of pipeline gas pressure, when the gas pressure at the front end of the Raoult nozzle is greater than or equal to the critical pressure of the Mach number set by the Raoult nozzle, the existing operation remains unchanged; when the gas pressure at the front end of the Raoult nozzle is less than the set Mach When the critical pressure is reached, the control system will automatically open the quick cut-off valve of the main blowing inert gas pipeline control valve group, and at the same time adjust the flow controller in the main blowing inert gas control valve group to adjust the valve opening to the gas pressure at the front end of the Raoult nozzle equal to Set the Mach number critical pressure. 6. The control method according to claim 5, characterized in that, in the non-hydrogen injection mode, the inert gas flow range of the Raoult nozzle is 500-2000Nm ³ /h, and the inert gas flow range of the shielding gas nozzle is 200- 800Nm ³ /h; In the hydrogen injection mode, the hydrogen gas flow range of the Raoult nozzle is 0-2500Nm ³ /h, the inert gas flow range of the Raoult nozzle is 0-1500Nm ³ /h, and the inert gas flow range of the protective gas nozzle is 200～800Nm ³ /h.

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