Automatic ignition system and method for roaster

Abstract

The invention belongs to the technical field of metallurgical baking, and relates to an automatic ignition system and method for a roaster, and the system comprises a plasma generator, a high-voltage power supply system, a spray gun, an auxiliary system and a control unit. A cathode of the plasma generator adopts a high-melting-point metal or hafnium embedded electrode and is provided with a conical tip, an anode adopts a copper alloy, and a 1-5mm discharge gap is formed between the cathode and the anode; the high-voltage power supply system consists of a high-frequency high-voltage generator and a DC power supply; laval nozzles are arranged at the front ends of the spray guns. The auxiliary system comprises a gas path system, a cooling system and a flame detector. The ignition method comprises the steps that after an instruction is received, working medium gas and high-frequency high-voltage breakdown gas are injected, the direct-current power source maintains the electric arc, 5,000-15,000 K plasma jet is generated, fuel is ignited, and the flame detector is in linkage control. The system solves the problems of delay, deflagration risk, short service life of parts and the like of a traditional igniter, millisecond-level reliable ignition is achieved, the service life of the electrode exceeds 5000 hours, and the system is suitable for a fuel gas / fuel oil roaster.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical baking, and relates to an automatic ignition system and method of a baking device. BACKGROUND

[0002] In a metallurgical production process, the baking of ladles, tundishes and the like is a necessary link to ensure the smooth progress of continuous casting or pouring processes. The reliability and efficiency of the ignition device of the baking device as a core device directly affect production safety, energy consumption and equipment maintenance costs. At present, the traditional ignition technology widely used in the industry mainly has the following significant defects:

[0003] 1. Insufficient ignition performance, prominent safety hazards

[0004] The existing mainstream igniters (such as electric spark plugs or resistance wire type igniters) have obvious shortcomings in harsh industrial environments:

[0005] High ignition delay and failure rate: especially in low-temperature, high-humidity or fuel gas pressure fluctuation conditions, ignition response is often delayed (the delay can reach several seconds) or even multiple ignition failures occur. This forces operators to frequently intervene manually, not only reducing automation levels, but also causing the accumulation of unburned gas in the furnace, which poses a threat to equipment and personnel safety when accidentally ignited.

[0006] Ignition energy limitation: the discharge energy of electric spark plugs is limited, making it difficult to reliably ignite low-calorific-value fuel gas or poorly atomized heavy oil; the resistance wire type igniter is limited by the heating rate and is prone to "blowout" in strong airflow environments, resulting in poor ignition stability.

[0007] 2. Short service life of key components, high maintenance cost

[0008] The structural defects of traditional igniters make it difficult for them to meet the stringent requirements of continuous production:

[0009] Rapid degradation of electric heating elements: the surface of the resistance wire is oxidized, the crystal grains are coarsened, and thermal stress fatigue causes brittle fracture due to long-term exposure to high-temperature combustion zones (>1000℃), with a typical service life of only 500-2000 hours. Frequent replacement not only increases spare parts costs, but also causes unplanned downtime.

[0010] Nozzle coking and blockage: carbon black and tar produced by incomplete combustion of fuel deposits at the nozzle of the igniter, gradually reducing the flow area or even completely blocking it. In order to maintain functionality, mechanical cleaning needs to be performed every week, which seriously affects the effective production time.

[0011] Insulation component aging and failure: the high-voltage insulator of the electric spark plug is prone to creepage or breakdown in high-temperature, carbon deposition environments, further reducing system reliability.

[0012] 3. System adaptability is poor, which restricts process optimization

[0013] Low fuel compatibility: existing devices are sensitive to changes in gas composition (such as fluctuations in coke oven gas impurities) or changes in liquid fuel viscosity, have weak ignition parameter adjustment capability, and are difficult to match the multi-fuel mixed combustion process requirements.

[0014] Insufficient environmental tolerance: high dust and strong corrosive atmosphere accelerate the damage of mechanical and electrical components, and the failure rate significantly increases in open air or high humidity conditions.

[0015] These problems collectively cause the ignition link of the roaster to become a weak point in the production chain, and it is urgent to solve the reliability, service life and maintainability bottlenecks through technical innovation. SUMMARY

[0016] Therefore, the purpose of the present application is to provide an automatic ignition system and method for a roaster to solve the existing problems.

[0017] To achieve the above purpose, the present application provides the following technical solution: an automatic ignition system for a roaster, comprising a plasma emitter, a high-voltage power supply system, an auxiliary system and a control unit; the plasma emitter comprises a cathode and an anode arranged coaxially, the cathode adopts a high-melting-point metal or hafnium embedded electrode and has a conical tip structure, the anode adopts a copper alloy material, and a discharge gap of 1-5 mm is formed between the cathode and the anode; the high-voltage power supply system is electrically connected with the plasma emitter, the high-voltage power supply system comprises a high-frequency high-voltage generator for breaking down the gas to generate an initial arc and a direct-current power supply for maintaining a stable plasma arc; a spray gun is connected with the outlet of the plasma emitter, and a high-temperature-resistant nozzle is arranged at the front end of the spray gun; the auxiliary system comprises a gas circuit system for providing working gas to the plasma emitter, a cooling system for cooling and a flame detector for monitoring the ignition state; the control unit is signal connected with the high-voltage power supply system, the gas circuit system, the cooling system, the flame detector and the main control system of the roaster, for receiving an ignition instruction and coordinating the control of the entire automatic ignition process.

[0018] Optionally, the output voltage of the high-frequency high-voltage generator is 10-20 kV.

[0019] Optionally, the output parameters of the direct-current power supply are 50-300 V voltage and 10-100 A current.

[0020] Optionally, the nozzle is a converging-diverging Laval nozzle.

[0021] Optionally, the working gas is compressed air, nitrogen or argon, and the gas flow of the gas circuit system is 0.5-5 L / min.

[0022] Optionally, the flame detector is an ultraviolet sensor or an ionization sensor.

[0023] An automatic ignition method of a roaster based on the automatic ignition system of the roaster, comprising the following steps:

[0024] S1, after the control unit receives the ignition instruction, the gas path system injects working gas into the electric arc chamber of the plasma emitter, and the cooling system is started at the same time;

[0025] S2, the high-frequency high-voltage power supply applies a pulse voltage of 10-20kV between the cathode and the anode to break down the gas medium and generate an initial electric arc;

[0026] S3, after breakdown, switch to DC power supply to maintain a large current arc with a voltage of 50-300V and a current of 10-100A, and ionize the working gas into high-temperature plasma;

[0027] S4, the high-temperature plasma forms a high-speed jet after being accelerated by the lance, and is sprayed into the mixed area of fuel and air to ignite the fuel;

[0028] S5, the flame detector is used to monitor whether the ignition is successful, if successful, the control unit opens the main burner valve and closes the plasma emitter, if failed, the fuel supply is cut off and an alarm is triggered.

[0029] Optionally, the temperature of the plasma jet is 5000-15000K, and the injection speed is 100-300m / s.

[0030] The beneficial effects of the present application are:

[0031] 1. The ignition capacity and reliability are significantly improved: the present application uses high-temperature plasma jet as ignition source, the core temperature can reach 5000-15000K, and the energy density is much higher than that of traditional electric spark or electric heating wire. This extremely high temperature jet can instantly gasify and ignite various fuels (including low heat value gas and atomized oil droplets), greatly shortening the ignition time, achieving nearly instantaneous reliable ignition, effectively avoiding the risk of fuel accumulation and explosion caused by ignition delay or failure, and greatly improving the safety and automation level of the entire roaster system.

[0032] 2. Significantly Extended Service Life and Reduced Maintenance Costs: The core ignition component of this system is the plasma emitter. Its cathode uses high-melting-point metals such as tungsten-thorium alloy, and the anode uses copper alloy with a cooling system. This allows the electrode assembly to withstand arc temperatures up to 3000℃, fundamentally solving the problem of short lifespan caused by oxidation and embrittlement of traditional heating wires. The service life is extended from hundreds of hours to thousands of hours or more. Simultaneously, the high-temperature, high-speed plasma jet has a self-cleaning effect on the spray gun nozzle, effectively reducing coking and clogging. This significantly reduces the frequency and number of downtime maintenance, lowering maintenance costs and minimizing production losses.

[0033] 3. Precise and controllable ignition process with strong adaptability: Through the integrated control unit, the high-voltage power supply, gas flow and cooling are coordinated and controlled, and the arc power can be precisely adjusted (1~5kW). This allows for flexible adjustment of ignition energy and jet characteristics according to different fuel types (such as gas or oil), composition and operating conditions, which significantly broadens the application range of the igniter and improves its adaptability to complex operating conditions.

[0034] 4. Robust safety interlock mechanism for safer operation: The system integrates ultraviolet or ionization flame detectors, enabling real-time and accurate monitoring of the ignition status and establishing a safety interlock with the main control system of the oven. In the event of ignition failure, the control unit immediately and automatically cuts off the fuel supply and issues an alarm, completely eliminating the possibility of continuous fuel leakage into the furnace, fundamentally eliminating the risk of deflagration, and ensuring the safety of equipment and personnel.

[0035] 5. Higher energy efficiency: Due to rapid and reliable ignition, fuel waste caused by multiple ignition attempts in traditional methods is avoided. At the same time, a stable high-energy ignition source helps the fuel to burn completely, indirectly improving the thermal efficiency of the oven.

[0036] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0038] Figure 1 This is a schematic diagram of an automatic ignition system for a baking oven.

[0039] Reference signs: spray gun 1, plasma emitter 2, high-frequency high-voltage generator 3, direct-current power supply 4, gas path system 5, cooling system 6, control unit 7. DETAILED DESCRIPTION

[0040] The present application is described in greater detail by the specific working examples below, from which other advantages and embodiments of the present application will become readily apparent to those of ordinary skill in the art and knowledge disclosed. The present application can also be implemented or applied in other different embodiments, and various modifications or changes can be made to the details without departing from the spirit of the present application based on different views and applications. It should be noted that the drawings provided in the following examples only schematically illustrate the basic concept of the present application, and the features in the following examples and embodiments can be combined with each other without conflict.

[0041] The drawings are only used for illustrative purposes, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present application; in order to better illustrate the embodiments of the present application, some components of the drawings may be omitted, enlarged or reduced, and do not represent the actual product size; for those skilled in the art, it is understandable that some known structures and their descriptions in the drawings may be omitted.

[0042] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative purposes, and cannot be understood as a limitation of the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0043] Please refer to Figure 1 The automatic ignition system of the roaster provided by the present application includes the following core components: spray gun 1, plasma emitter 2, high-frequency high-voltage generator 3, direct-current power supply 4, gas path system 5, cooling system 6 and control unit 7.

[0044] The plasma emitter 2 is connected with the high-frequency high-voltage generator 3 and the direct-current power supply 4 through a high-voltage cable; the gas path system 5 supplies working gas to the plasma emitter 2 through a pipeline; the cooling system 6 cools the plasma emitter 2 and the spray gun 1 through a water path or an air duct; the spray gun 1 is installed at the outlet end of the plasma emitter 2, and the spray direction is aligned with the combustion zone of the roaster; the control unit 7, as the brain of the system, is connected with the high-frequency high-voltage generator 3, the direct-current power supply 4, the gas path system 5, the cooling system 6, and the roaster master control system and the flame detector through signal lines, receives instructions and sends control signals, and coordinates the entire ignition process.

[0045] Example one: automatic ignition for a gas roaster

[0046] This embodiment takes igniting natural gas as an example to illustrate the working process of the present application in detail.

[0047] 1. System configuration and parameter setting:

[0048] The plasma emitter 2: the cathode adopts tungsten- thorium alloy material and is processed into a conical tip; the anode adopts chromium-plated copper alloy. The discharge gap between the cathode and the anode is set to 3 mm.

[0049] High-voltage power supply system: the high-frequency high-voltage generator 3 is set to output a pulse voltage of 15 kV; the direct-current power supply 4 is set to output 100 V / 30 A.

[0050] The spray gun 1: the nozzle adopts a copper Laval nozzle structure.

[0051] The gas path system 5: the working gas is compressed air, and the flow rate is set to 2.5 L / min.

[0052] The cooling system 6: circulating water cooling is adopted to forcibly cool the plasma emitter 2 and the spray gun 1.

[0053] The flame detector: an ultraviolet flame sensor is selected.

[0054] The control unit 7: a PLC controller is adopted, and an ignition logic program is written.

[0055] 2. Specific steps of the automatic ignition method:

[0056] Step one (pre-starting stage): the roaster master control system sends an ignition instruction to the control unit 7. The control unit 7 starts the gas path system 5 and the cooling system 6. Compressed air is injected into the arc chamber of the plasma emitter 2, and the cooling water starts to circulate.

[0057] Step two (high-voltage breakdown stage): The control unit 7 triggers the high-frequency high-voltage generator 3 to work, applying a high-voltage pulse of 15 kV between the cathode and anode of the plasma emitter 2. The high-voltage pulse breaks down the compressed air medium in the 3 mm gap, generating an initial electric spark and forming a conductive path.

[0058] Step three (arc stabilization and plasma generation stage): After successful breakdown, the circuit impedance drops sharply, and the control unit 7 controls the power supply to switch to the direct-current power supply 4 for power supply. The direct-current power supply maintains the arc stable combustion at a voltage of 100 V and a current of 30 A. The strong current continuously heats the passing compressed air to a high temperature, causing it to ionize and form a plasma with a temperature of about 10,000 K.

[0059] Step four (spraying and ignition stage): The high-temperature plasma is accelerated by the compressed air and passes through the Laval nozzle of the lance 1, forming a plasma jet with a speed of up to 200 m / s, which is sprayed from the nozzle of the lance 1. At this time, the gas main valve of the oven has been pre-opened by a small part (after purging), forming a combustible gas atmosphere. The high-temperature and high-speed plasma jet ignites the mixed gas of natural gas and air instantaneously, forming a stable flame.

[0060] Step five (state confirmation and system switching): The ultraviolet flame detector monitors the combustion state in real time and feeds back the "flame established" signal to the control unit 7. After the control unit 7 confirms successful ignition, it immediately issues an instruction to close the high-frequency high-voltage generator 3 and the direct-current power supply 4, stops the plasma generation, and fully opens the gas main valve, and the oven enters the normal combustion mode. If no flame signal is detected within the set time (e.g., 3 seconds), the control unit 7 determines that the ignition has failed, immediately closes the gas supply, stops the ignition system, and issues an audible and visual alarm to prompt the staff to check.

[0061] Example two: automatic ignition for oil-fired ovens

[0062] This example takes igniting heavy oil as an example to illustrate the application of the present application in oil ignition.

[0063] 1. System configuration and parameter adjustment: The system hardware structure is the same as in Example 1.

[0064] The key parameters are adjusted as follows:

[0065] Since heavy oil ignition requires higher energy, the output parameters of the direct-current power supply 4 are adjusted to 250 V / 60 A to generate a plasma jet with higher power and more concentrated energy.

[0066] The working gas of the gas path system 5 is changed to nitrogen, and the flow rate is set to 3.0 L / min to avoid carbonization and coking of the fuel oil.

[0067] 2. Specific steps of the automatic ignition method:

[0068] Step one: after receiving the ignition instruction, the control unit 7 starts the gas system 5 (injects nitrogen), the cooling system 6 and the fuel combustion fan in turn.

[0069] Step two: the high-frequency high-voltage generator 3 works to generate an electric spark to break the gas.

[0070] Step three: switch to the high-power DC power supply 4 (250V / 60A) to form a high-intensity plasma arc.

[0071] Step four: the high-temperature plasma jet (temperature up to 12,000K or more) is sprayed from the torch 1 to directly act on the heavy oil mist atomized by the oil gun. The high temperature of the plasma jet first gasifies the oil droplets instantaneously, then ignites them to form a stable small torch.

[0072] Step five: after the flame detector detects the small torch, it feeds back a signal to the control unit 7. The control unit 7 confirms that the ignition is successful, then closes the plasma generation system, and controls the oil gun to increase the oil quantity, so that the oven enters the normal combustion state. The safety interlocking logic here is exactly the same as that in Example 1, which ensures that the oil circuit is immediately cut off and an alarm is given when the ignition fails.

[0073] In summary, the two examples demonstrate the wide applicability and high reliability of the present application, effectively solving various problems existing in the traditional ignition method in the metallurgical oven.

[0074] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A toaster automatic ignition system characterized by: The plasma emitter, the high-voltage power supply system, the auxiliary system, and the control unit are included. The plasma emitter includes coaxially arranged cathode and anode, the cathode adopts high melting point metal or hafnium embedded electrode and has a conical tip structure, the anode adopts copper alloy material, and a discharge gap of 1-5 mm is formed between the cathode and the anode. The high-voltage power supply system is electrically connected with the plasma emitter, and the high-voltage power supply system includes a high-frequency high-voltage generator for breaking the gas to generate an initial arc and a direct-current power supply for maintaining a stable plasma arc. The spray gun is connected with the outlet of the plasma emitter, and the front end of the spray gun is provided with a high-temperature-resistant nozzle. The auxiliary system includes a gas circuit system for providing working gas to the plasma emitter, a cooling system for cooling, and a flame detector for monitoring the ignition state. The control unit is signal connected with the high-voltage power supply system, the gas circuit system, the cooling system, the flame detector, and the main control system of the oven, for receiving an ignition instruction and coordinating the control of the whole automatic ignition process.

2. An automatic igniter system for a roaster as defined in claim 1, wherein: The output voltage of the high-frequency high-voltage generator is 10-20 kV.

3. An automatic igniter system for a roaster as defined in claim 1, wherein: The output parameters of the direct-current power supply are 50-300 V voltage and 10-100 A current.

4. An automatic igniter system for a roaster as defined in claim 1, wherein: The nozzle is a converging-diverging Laval nozzle.

5. An automatic igniter system for a roaster as defined in claim 1, wherein: The working gas is compressed air, nitrogen or argon, and the gas flow of the gas circuit system is 0.5-5 L / min.

6. An automatic igniter system for a roaster as defined in claim 1, wherein: The flame detector is an ultraviolet sensor or an ionization sensor.

7. A method for automatic ignition of a roaster based on the automatic ignition system of any one of claims 1 to 6, characterized in that, The method includes the following steps: S1, after the control unit receives the ignition instruction, the gas circuit system injects working gas into the arc chamber of the plasma emitter, and the cooling system is started at the same time; S2, the high-frequency high-voltage power supply applies a pulse voltage of 10-20 kV between the cathode and the anode to break the gas medium and generate an initial arc; S3, after breaking, switch to power supply by the direct-current power supply to maintain a large-current arc with 50-300 V voltage and 10-100 A current, and ionize the working gas into high-temperature plasma; S4, the high-temperature plasma forms a high-speed jet after being accelerated by the spray gun, and is sprayed into the mixed area of fuel and air to ignite the fuel; S5, the flame detector is used to monitor whether the ignition is successful, if successful, the control unit opens the main burner valve and closes the plasma emitter, if failed, the fuel supply is cut off and an alarm is triggered.

8. A method of automatically igniting a roaster according to claim 7, wherein, The temperature of the plasma jet is 5000-15000 K, and the jet speed is 100-300 m / s.

Images