GB/T 33969-2026Technical specification for oxygen-enriched pulverized coal injection into blast furnaces (English PDF)

5.1 Requirements for raw coal

5.1.1 The lower heating value of bituminous coal shall not be lower than 26,000 kJ/kg, and the lower heating value of anthracite shall not be lower than 29,000 kJ/kg.

5.1.2 The sulfur content of raw coal shall meet the requirements of GB 50427; the alkali metal content in the ash of raw coal shall be less than 1.0%.

5.1.3 The Hardgrove Grindability Index of raw coal should be 50~90, the angle of repose should be less than 42°, and the jetting and flowability index should be greater than 60.

5.1.4 The raw coal used should be a type of coal that does not coke, and the plastic layer index of bituminous coal should be less than 10 mm.

5.1.5 The moisture content of anthracite should be less than 10%, and the moisture content of bituminous coal should be less than 16%.

5.2 Fuel Requirements for Furnace

5.2.1 After pulverization, the ash melting point of the pulverized coal injected into the blast furnace should be greater than 1250°C, and the moisture content should be less than 2%. Anthracite injection. When using pulverized coal injection, 70% to 80% of the pulverized coal entering the furnace should have a particle size smaller than

0.074 mm; when using full bituminous coal injection, the particle size of the pulverized coal entering the furnace should be smaller than

0.074 mm. The ash content should reach 60%~65%. The requirements for ash and sulfur content of pulverized coal entering the furnace for different blast furnaces should comply with the provisions of Table 1.

5.2.2 The particle size of the blast furnace injection coking dust should not be larger than that of the anthracite entering the furnace, and the ash content should not exceed 12%.

5.2.3 When injecting biomass, organic solid waste (waste plastics, waste rubber), or other fuels into the blast furnace, the particle size of the feed material should not exceed that of the bituminous coal, and the moisture content should be... The content should be less than 2%, and the content of ash, alkali metals, chlorine, sulfur and other elements should not exceed the requirements of pulverized coal.

5.2.4 When injecting circulating gas, hydrogen-rich gas, or pure hydrogen gas into a blast furnace, the gas should be purified and pressurized first to meet the requirements for blast furnace injection. Require.

6.1 General Requirements

6.1.1 Methods for determining the oxygen enrichment rate and pulverized coal injection rate in a blast furnace The oxygen enrichment rate and pulverized coal injection rate in a blast furnace should be determined comprehensively based on furnace volume, raw material conditions, smelting objectives, and techno-economic analysis. This should be achieved through a combination of oxygen enrichment and pulverized coal injection. Coal synergistic optimization aims to achieve stable blast furnace operation, reduce fuel ratio, and increase production while saving energy.

6.1.2 Selection Methods for High-Performance Coal Types The selection of high-performance coal types should involve evaluating the cost-effectiveness of pulverized coal injection, based on the principle of high effective calorific value and high cost-effectiveness index. The method is described in Appendix A.

6.1.3 Optimal Matching Methods for Multiple Coal Types

6.1.3.1 The effective calorific value, combustibility, and volatile matter of the mixed pulverized coal should be within the safe range of the pulverizing and injection system.

6.1.3.2 First, select several coal types with high cost-effectiveness based on the principle of evaluating the cost-effectiveness of pulverized coal; then, based on the safety conditions of the pulverizing and injection systems, determine... The upper limit of volatile matter in pulverized coal is determined, and different coal types are mixed and blended. The mixed pulverized coal is then selected based on the principle of cost-effectiveness evaluation to select the most cost-effective option. Pulverized coal blending scheme.

6.1.4 Method for determining the economical amount of pulverized coal injected into a blast furnace The pulverized coal injection rate in the blast furnace should be between 150 kg/t and.200 kg/t. The economical pulverized coal injection rate is the rate at which the cost of molten iron is lowest after pulverized coal injection in the blast furnace. The type of coal should be determined based on the raw material conditions (quality and price) and operating level of different blast furnaces.

6.1.5 Method for determining the economic oxygen enrichment rate of a blast furnace The oxygen enrichment rate of a blast furnace should be between 3% and 10%. The economical oxygen enrichment rate should take into account the oxygen injection rate, pulverized coal injection rate, coal-coke replacement ratio, and oxygen cost. The calculation method can be found in Appendix B.

6.2 Raw Coal Drying System

6.2.1 The temperature of the drying gas in the flue gas furnace shall be controlled within the required temperature range (250±50)°C at the coal mill inlet. Based on production conditions, the flue gas furnace... Vertical chamber-shaped, horizontal cylindrical, and vertical cylindrical shapes should be selected.

6.2.2 To ensure safe operation, the flue gas furnace cavity temperature should not exceed 1200°C and should not be lower than 700°C. The temperature of the drying gas should be... The temperature should not exceed 400°C and should be maintained between 180°C and 350°C. The oxygen content of the drying gas should not exceed 6%. (This refers to the temperature range for dry gas during full-bituminous coal injection.) The oxygen content should not exceed 3%. Key parameters of the dry gas should be strictly controlled, and a graded early warning mechanism should be set up to issue early warnings if the parameters exceed the specified range.

6.3 Powdering System

6.3.1 The powder making system shall adopt a full negative pressure powder making process with one fan and one-stage bag filter.

6.3.2 The raw coal bunker adopts a hyperbolic design, with the lower conical side forming an angle greater than 65° with the horizontal. Its effective coal storage capacity should be sufficient for the operation of the coal mill. For coal consumption of 8-10 hours, an electromagnetic iron separator should be installed in front of the raw coal silo. The raw coal silo should be equipped with temperature monitoring and oxygen content monitoring devices.

6.3.3 A sealed weighing type coal feeder should be selected.

6.3.4 A medium-speed coal mill should be selected. Ensure lubrication of the main shaft and rollers, prevent overheating, and ensure stable motor current (fluctuations should not exceed [a certain value]). 10A) Irregular wear on the surface of the grinding rollers, etc. The inlet temperature should be controlled to be 50°C lower than the ignition point of pulverized coal, and the inlet temperature fluctuation should not exceed [a certain value]. The outlet temperature should be (80±10)°C. When using a flue gas self-circulation process, the outlet temperature should be controlled at the upper limit of around 90°C. The oxygen content in the flue gas should be controlled at around 6%, and should not exceed 10%. When using full bituminous coal injection, the oxygen content at the mill inlet should not exceed 4%, and the oxygen content at the mill outlet should also be controlled. The slag inlet is designed to prevent air backflow. The negative pressure at the pulverizer inlet is controlled between 300Pa and 1000Pa, with the principle of preventing coal from escaping from the inlet.

6.3.5 Pulse-type baghouse dust collectors should be selected. Nylon needle-punched felt is a suitable material for the bags. Baghouse dust collectors should prevent localized dust accumulation and spontaneous combustion. The external ignition source is used for ignition. When using anthracite injection, the inlet temperature of the filter bag should be maintained at around 80°C, and should not exceed 90°C. The outlet oxygen temperature of the filter bag should be... The content should not exceed 12%; when injecting whole bituminous coal, the inlet temperature of the filter bag should be maintained at around 70°C, and should not exceed 80°C, and the oxygen content at the outlet of the filter bag should be... The dust content should not exceed 6%; the dust content of the flue gas at the outlet of the bag filter should be less than 10 mg/m3.

6.3.6 The air volume of the main exhaust fan should be greater than or equal to the air volume required when the coal mill has the maximum hourly output, and the air pressure should be greater than the total pressure of the pulverizing system. With a resistance of 30%, the temperature should be greater than 150°C or 50°C higher than the normal temperature at that point.

6.3.7 The pulverizing system should be kept clean and free of foreign objects on the equipment surface, and free of accumulated powder and flammable materials in the plant. Regular cleaning should be performed; the dust collector should be inspected and cleaned regularly. In addition to bag enemas; regularly monitor the oxygen and combustible gas content in the system; regularly calibrate the temperature and pressure gauges of the pulverizing system; the system pressure... Pressure vessels should comply with TSG21; fire protection facilities and explosion-proof equipment should be inspected regularly.

6.4 Pulverized Coal Conveying System

6.4.1 The temperature of pulverized coal inside the silo pump should not exceed 80°C, and the storage time should not exceed 2 hours.

6.4.2 The coal conveying system should have flexible coal supply capabilities. During production, it should ensure that changes in the coal conveying pipeline pressure and the readings on the electronic scales of the coal receiving tank are monitored. The gas flow rate and changes are normal. If a blockage occurs, it can be treated using a segmented purging method or a backflushing method.

6.4.3 The pulverized coal receiving tank shall be equipped with an electronic weighing device to verify the output of the silo pump and the receiving tank's capacity. Pulverized coal silos, silo pumps, coal storage tanks, and sprayers... The inner walls of the blowing tank and other tanks, as well as the ash hopper walls and powder discharge pipes of powder collection equipment, should be smooth. The angle between the wall of the discharge cone and the horizontal plane should not be less than 70° or similar. Use inert gas fluidizers. The design, manufacture, and installation of pressure vessels such as silo pumps, coal storage tanks, injection tanks, and air distributors should comply with... The provisions of TSG21.

6.4.4 The inner wall of the pulverized coal pipeline should be smooth to reduce the number of flange connections on the pipeline.

6.4.5 The layout of pulverizing pipelines should avoid creating dead zones where pulverized coal can accumulate, and the angle between the pipelines and the horizontal plane should not be less than 45°. When laying horizontal pipelines, the... The design flow velocity under constant load conditions should not be less than 25 m/s.

6.4.6 The minimum load design flow velocity in the pulverized coal pipeline after the coal mill outlet should not be less than 15 m/s. (Flow velocity within coal conveying and pulverized coal injection pipelines) The settling velocity should not be less than

1.25 times the settling velocity.

6.4.7 The design of the negative pressure system terminal shall comply with the provisions of GB 16543, and the oxygen content shall not exceed 12%. During full-bituminous coal injection, the negative pressure... The oxygen content at the end of the system should not exceed 8%.

6.4.8 When compressed air is used as the conveying medium for pulverized coal and injection, it should be able to be immediately switched to nitrogen in an emergency. (Full bituminous coal injection) When using nitrogen or other inert gases as carrier gases, nitrogen or other inert gases should be used.

6.4.9 The coal powder silo of the pulverizing system shall be equipped with a nitrogen flow modeization device and a nitrogen filling device.

6.4.10 The pressurization and fluidizing medium for pressure vessels such as silo pumps, coal storage tanks, and injection tanks in pulverized coal conveying and injection systems should be nitrogen or other gases. Inert gas. Silo pumps, coal storage tanks, pulverized coal tanks, pulverized coal silos, and other equipment or devices should be equipped with emergency connection valves and compressed air pipelines. It has a head and can be interchanged with nitrogen pipelines.

6.5 Pulverized Coal Injection System

6.5.1 The arrangement of the injection tanks in the injection system is divided into series tank type and parallel tank type. Parallel tank type should be selected for direct injection, while series tank type can be selected for indirect injection. Tank type.

6.5.2 When pulverized coal is injected into the blast furnace from the pulverized coal injection tank, the pulverized coal discharge method should be a main pipe plus a distributor.

6.5.3 The pulverized coal spray gun should be made of stainless steel heat-resistant steel pipe, and the tip of the spray gun should be made of a material with better heat resistance. Water cooling should be installed on the direct-blowing pipe. Or air-cooled jacket.

6.5.4 The pulse-jet system should be cleaned using a sweeping method. The dust collector should be inspected regularly, and accumulated dust in the filter bags should be removed. The oxygen and combustible gas levels in the system should be tested regularly. The content of the substance; regularly calibrate the temperature and pressure instruments of the pulverizing system.

6.5.5 When injecting bituminous coal or granular coal, a temperature sensor shall be installed at the bend of the pipe to monitor temperature changes in the area, and the temperature shall be monitored when the temperature approaches the auto-ignition threshold or abnormally rises. In a timely manner, problems such as coal accumulation and frictional heating should be investigated and addressed; pressure monitoring devices should be installed along the pipeline to capture pressure fluctuations in real time and detect any deviations beyond the safe zone. In case of anomalies, early warnings will be issued to promptly investigate and resolve issues such as pipe blockages, leaks, or unstable airflow, and to prevent safety accidents.

6.5.6 Ambient oxygen and carbon monoxide concentrations should be measured regularly; when using nitrogen for pressurized fluidization and purging, nitrogen supply should be provided. Gas leak alarm; technicians and operators should receive regular training on relevant production operations and fire and explosion prevention.

6.6 Oxygen Delivery System

6.6.1 After the oxygen pressure is regulated and controlled by the pressure regulating station, the oxygen enrichment before the blower should be reduced to 0.03MPa~0.015MPa, and the oxygen enrichment after the blower should be reduced to... 0.6MPa~0.8MPa, and shall comply with the provisions of GB 16912.

6.6.2 Each branch pipe section should be equipped with its own safety control unit to implement single-branch pipe safety control and protection.

6.6.3 The oxygen supply system should be able to supply oxygen evenly to each oxygen lance.

6.6.4 When a blast furnace tuyeres malfunction, the oxygen supply to the corresponding oxygen lance should be cut off in a timely manner and nitrogen should be supplied.

6.6.5 The same compressed air source shall be used for both jetting and canning.

6.6.6 An air drying and purification device should be used to remove water and oil from the blown air.

6.6.7 Oxygen delivery pipelines should use stainless steel pipes and copper valves. When connecting to the oxygen lance, a section of high-pressure resistant metal hose should be used. All pipe valves, flanges, and gaskets used for oxygen supply should be degreased.

6.6.8 The oxygen supply facilities consist of two parts. oxygen transmission pipelines and regulating and control devices. Each blast furnace should be equipped with one set of regulating and control pipelines and... valve.

7.1 Safe Operation of Blast Furnace Pulverized Coal Injection

7.1.1 Blast Furnace Pulverized Coal Injection Start-up Operation The pulverized coal injection tank is used to inject coal into the blast furnace as follows:

a) Determine the amount of coal to be injected and insert the spray gun;

b) Open the blower valve;

c) Open all valves on the pulverized coal injection pipeline;

d) Open the automatic shut-off valve and activate the automatic function;

e) Open the pulverized coal injection tank pressurization valve to make the pressure inside the tank 0.2MPa~0.3MPa higher than the blast furnace pressure, then close the pulverized coal injection tank pressurization valve;

f) Open the valve on the spray gun and close the backflush valve;

g) Open the coal valve and pressure-replenishing valve and adjust them to the injection position;

h) Check that there is no coal leakage at each pulverized coal injection vent and nozzle, and that the coal flow is on the center line of the vent;

i) Notify the blast furnace that pulverized coal has been sprayed on.

7.1.2 Coal type switching operation during blast furnace periodic maintenance During regular blast furnace maintenance, bituminous coal production should be stopped. After the blast furnace begins supplying air and there is no hot blast stove flue gas being introduced, anthracite coal pulverization should be used exclusively. Coal injection can be resumed shortly after the furnace is blasted.

7.1.3 Short-term (less than or equal to 8 hours) coal shutdown operation First, close the coal valve; then, according to the blast furnace requirements, stop the blowing air from the corresponding tuyer and pull out the corresponding tuyer nozzle.

7.1.4 Long-term (more than 8 hours) coal shutdown operation First, the pulverized coal in the injection tank group should be completely sprayed out

0.5 to 1 hour in advance according to the plan; then, according to the blast furnace requirements, the coal valve should be closed and the furnace stopped. Stop the airflow from the corresponding air outlet and pull out the corresponding air outlet spray gun.

7.2.1 Oxygen supply start-up operation

7.2.1.1 After equipment commissioning, cleaning, and other work are completed, oxygen should be supplied to the first shut-off valve before the pressure reducing valve group. Production can only begin when the blast furnace is operating normally. Oxygen delivery operation.

7.2.1.2 Confirm that all valves in the pressure reducing valve group are in the closed position, including the quick-shut-off valve, pressure reducing valve (pressure regulating valve), flow regulating valve, etc., which are remotely operated. The operation of the valves should be confirmed. All instrument readings should be within normal ranges.

7.2.1.3 Open the nitrogen valve to balance the nitrogen pressure among the valves in the pressure reducing valve group system. If there is no nitrogen pipeline supply, a temporary nitrogen supply can also be used. Each nitrogen cylinder is used for nitrogen filling and pressure equalization. Only when the pressure difference across the valve is less than

0.3 MPa can the first oxygen cylinder before the main oxygen supply line enters the pressure reducing valve assembly be opened. Open the main gas valve, then open the valves at the outlet of the pressure reducing valve group and the main blast furnace cold air pipe. After opening these two valves, personnel should evacuate the valve group area and close the valves. The quick-shut-off valve, pressure regulating valve, and flow regulating valve in the closed pressure reducing valve assembly.

7.2.1.4 For remote operation, open the quick-close valve, adjust the pressure regulating valve until the pressure before and after the regulating valve reaches the specified value, then open... The flow regulating valve supplies oxygen into the main cold air duct. The oxygen flow rate is adjusted according to the required oxygen consumption to achieve the normal usage.

7.2.2 Short-term (less than or equal to 4 hours) oxygen suspension operation The quick-close valve should be closed first, followed by the flow regulating valve. If the oxygen pressure regulating station is far from the cold air duct, the quick-close valve should be equipped with... Place it in an area close to the cold air duct. The quick-shut-off valve should be equipped with cold air pressure, overload, and overpressure protection.

7.2.3 Long-term (more than 4 hours) oxygen outage operation First, close the quick-close valve, then close the oxygen flow regulating valve, followed by the pressure regulating valve, and finally close the main oxygen line and pressure reducing valve. The main shut-off valve connected to the valve assembly and the shut-off valve connected to the main cold air duct. The oxygen in the main oxygen duct and pressure reducing valve assembly should be completely released, using nitrogen and dry gas. Dry air replacement and pressure maintenance.

8.1 Maintenance of Metering Equipment

8.1.1 All metering instruments for pulverized coal, oxygen, and carrier gas should be included in the regular maintenance plan, and their calibration cycle should comply with the national metrological verification regulations. The requirement is to ensure the accuracy and reliability of measurement data.

8.1.2 A ledger and maintenance records for metering equipment should be established. Key metering instruments, such as single-branch coal powder flow meters, should be cleaned and calibrated regularly. Accuracy and zero-point verification.

8.1.3 During maintenance work, safe operating procedures shall be followed. For oxygen metering pipelines, dry, oil-free nitrogen gas should be used for purging before maintenance. Sweep to ensure there is no grease or flammable material in the pipeline.

8.1.4 Maintenance of the metering system should include inspection of data transmission lines and display units to ensure that the data displayed in the central control room matches the readings of the field instruments. The numbers are consistent.

8.2 Intelligent Control

8.2.1 The pulverized coal injection system should establish an integrated control system based on an expert system or intelligent algorithm to ensure the pressure of the main oxygen pipe and the flow in each branch pipe. Intelligent linkage and precise matching between the quantity and the pulverized coal injection system.

8.2.2 The system should have intelligent diagnostic and early warning functions, automatically judging and issuing early warnings by analyzing abnormal fluctuations in pulverized coal flow and pressure in real time. Malfunctions such as coal gun blockage, damage, or pipeline leakage.

8.2.3 The intelligent control system should be able to automatically calculate and dynamically adjust the pulverized coal distribution of each branch pipe according to the real-time changes in the blast furnace condition, ensuring the injection... Automatic optimization and stable control of coal quantity.

8.2.4 When the system triggers the accident shutdown condition, the intelligent control system should be able to automatically execute the preset safety interlock program and generate an accident handling response. Report.

8.2.5 The intelligent control system should have data storage and historical trend analysis functions.