Emergency response measures for the Space Powder Gasifier

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Emergency Handling Measures for Aerospace Powder Coal Gasification Furnace I. General Provisions 1.1 Scope of Application These measures are applicable to the entire system of the aerospace powder coal gasification unit: units such as coal grinding and drying, coal powder storage bins, pressurized feeding, the gasification furnace itself, quenching chambers, slag discharge systems, waste boilers/washing towers, gas transportation, and utility systems (electric power/instrument air/circulating water/nitrogen), for the emergency handling of abnormal operating conditions and accidents in these units. 1.2 General principles for emergency response 1. Human safety first: Prioritize prevention of poisoning, explosions, burns, and suffocation. 2. First, cut off the sources of danger: stop the supply of oxygen, coal, and gas first, then control the temperature and pressure. 3. Prioritize protecting critical equipment: burner cooling water, quenching water, water wall, and instrumentation system. 4. Operation at excessive temperature, pressure, or with faults is strictly prohibited. 5. Parking requires replacement, maintenance requires analysis, hot work requires permits, and entry requires approval. II. Emergency Shutdown (ESD) Trigger Conditions: An emergency shutdown shall be initiated immediately if either of the following conditions is met: 1. Severe over-temperature in the vaporizer (chamber/exit temperature exceeding the design value by +50°C) or over-pressure (exceeding the design value by +0.5 MPa), with no possibility of controlling it. 2. The low-low interlock for burner cooling water flow/pressure is triggered, preventing the standby pump from starting. 3. Severe leaks, fires, explosions, and jetting of flames from nozzles, quenching chambers, and coal gas pipelines. 4. A complete power outage across the plant, voltage fluctuations, interruption of instrument air supply, and shutdown of circulating water lead to loss of system control. 5. The chilled water pump has stopped completely; the lock-hopper system is malfunctioning and cannot discharge slag, and the slag outlet is blocked. 6. Emergency gas cut-off, explosion, fire, and large-scale CO leakage in downstream equipment. 7. Oxygen system leakage, uncontrolled oxygen flow rate, oxygen purity < 99.6%. 8. Fire in coal powder silo/pipeline, abnormal temperature rise, CO alarm. III. Standard Operating Procedures for Emergency Shutdown (ESD) 3.1 Interlocked Automatic Action 1. Rapid shutdown: Oxygen quick cut valve, coal powder feed valve, high-pressure nitrogen sealing valve. 2. Open: Nitrogen purging valve, flare/pressure relief valve. 3. Stop: feeding, pressurization, hopper circulation, coal grinding and drying system. 4. Self-protection: Automatic startup of the burner cooling water, quenching water, and seal gas systems. 3.2 Manual replenishment operation at the control center: 1. Ensure that oxygen, coal powder, and feed gas are completely cut off, so that no medium enters the furnace. 2. Control the pressure of the gasification furnace to be released slowly (≤0.1 MPa/min); rapid pressure release is strictly prohibited to avoid damaging the water wall. 3. Maintain normal operation of the burner cooling water, quenching water, and sealing gas, with flow rates/pressures meeting the specified standards. 4. Close the system valves downstream, and vent all gas to the flare. 5. Use nitrogen for continuous displacement to maintain a slight positive pressure in the system (0.02–0.05 MPa) to prevent air from entering. 3.3 On-site operations 1. Immediately go to the site to check the valve status, as well as for any leaks, fires, or abnormal noises. 2. It is strictly prohibited to open manholes, handholes, and sampling ports without first performing displacement. 3. Establish a safety zone, prohibit unauthorized personnel from entering, and strictly forbid the use of open flames, mobile phones, and metal objects that could cause collisions. IV. Emergency response measures for typical accidents (full version)
(1) Overheating of the gasifier
Phenomenon: The furnace temperature and the temperature of the outgoing gas rise sharply, exceeding the designed values. - The oxygen-coal ratio is on the high side; there are fluctuations in pulverized coal flow or coal supply interruption. - Abnormal rise in the wall temperature of the water wall; local overheating. Reason - Imbalanced oxygen-to-coal ratio, excessive oxygen/insufficient coal powder. - Coal powder bridging, coal interruption, and poor conveyance. - Instrument failure, false flow/temperature readings. - Sudden increase in load, insufficient steam ratio. Countermeasures: 1. Immediately reduce the oxygen flow rate (by 10%–20%) while simultaneously reducing the load. 2. Check the coal powder flow rate, and ensure proper fluidization, backblowing, as well as the proper operation of the silo pump and pipelines. 3. Adjust the steam/oxygen-coal ratio and increase the amount of coolant. 4. Check the temperature and flow meters to eliminate false readings. 5. Temperature continuously exceeds limits and cannot be controlled → Immediately initiate an emergency shutdown. (II) Gasifier overpressure phenomenon – The system pressure rises rapidly, approaching/reaching the set point at which the safety valve activates. - There is high back-system resistance, stuck valves, and blocked pipes. - Flame/tank venting is not smooth. Reason - Faulty outlet valve, high resistance in the scrubber/waste boiler. - The slag outlet is blocked, resulting in poor slag discharge. - The rear system suddenly lost pressure; there was a failure in the venting system. - The instrument is malfunctioning. Remedial actions: 1. Check whether the system valves, flare systems, and venting systems are unobstructed. 2. Perform appropriate manual pressure relief (≤0.1 MPa/min); pressure buildup is strictly prohibited. 3. Reduce the load and check whether the lockhopper slag discharge and slag outlet are blocked. 4. Pressure out of control → Emergency shutdown. (III) Burner cooling water failure (most dangerous) Symptoms – low cooling water flow, low pressure difference, high outlet temperature. - Signs of burner leakage, flaming, deformation, and burnout. Reason - Main pump tripped, standby pump did not start automatically. - Pipeline leakage, filter clogging. - The water supply is cut off. Remedial actions: 1. Immediately start the backup pump and check that pressure and flow return to normal. 2. Check for leaks in the pipelines, flanges, and pump body, and clean the filter. 3. Traffic cannot be restored → Immediate emergency shutdown. 4. It is strictly prohibited to operate the burner without water supply. (IV) Quench water/quench chamber failure – Symptoms: very low quench water flow rate, large fluctuations in quench chamber liquid level. - High outlet gas temperature, severe water contamination, and risk of internal component damage. Remedial measures: 1. Immediately start the backup quench water pump. 2. Check whether the filters, valves, and pipelines are clogged. 3. Stabilize the liquid level to prevent vacuum or overfilling. 4. Low flow low interlock triggered → Emergency stop. (5) Abnormalities in the coal powder system (coal supply interruption/bridging/ignition) 1. Coal supply interruption/bridging – Phenomenon: coal powder flow is zero, and the furnace temperature rises rapidly. - Treatment: 1. Immediately reduce oxygen levels and decrease the workload. 2. Fluidize, back-blow, and clear silo pumps and pipelines. 3. Prolonged coal outage (>5 min) → Shutdown. 2. Coal powder bin/pipeline fire - Symptoms: rising temperature, smoking, CO alarm. - Treatment: 1. Cut off the feed and isolate the system. 2. Use nitrogen for fire suppression, sealing, and inerting. 3. It is strictly prohibited to open manholes to prevent air from entering and causing an explosion. (VI) Abnormalities in the oxygen system – Sudden increase/decrease in oxygen flow, loss of control over valve positions, leaks. - The furnace temperature soars, posing a risk of explosion. Remedial measures: 1. Immediately close the oxygen quick-cut valve to cut off the gas supply. 2. Purge the oxygen pipeline with nitrogen. 3. Oxygen delivery is strictly prohibited when it contains oil or water, or when the flow rate or pressure is excessive. 4. Uncontrollable → Emergency stop. (7) Faults in the lock-hopper slag discharge system: Symptoms – interruption in slag discharge, blockage of the slag outlet, high pressure difference, and fluctuating liquid levels. Remedial actions: 1. Check the flushing water, valve operation, and liquid level. 2. Back-blow, clear, and re-establish the lockhopper cycle. 3. Inability to discharge slag for an extended period (>30 min) → Reduce load and prepare for shutdown. VIII) Measures for gas leaks/CO poisoning: 1. Immediately cut off the gas supply and isolate the source of the leak. 2. Evacuate to the upwind direction, wearing air respirators. 3. Forced ventilation is required; all sources of fire are strictly prohibited. 4. Major leakage → Emergency shutdown + nitrogen purging. 5. Poisoned persons: Move them to a place with fresh air; perform cardiopulmonary resuscitation if necessary, and take them to the hospital. (IX) Emergency response measures for fires and explosions: 1. Immediately shut down the equipment urgently and cut off oxygen, coal powder, and gas. 2. Nitrogen purging, isolation system. 3. Use dry powder or carbon dioxide fire extinguishers; never use water directly on electrical and high-temperature equipment. 4. Set up an on-site perimeter, evacuate people, and call 119. (10) Emergency response for utility disruptions 1. Power outage/flickering power – Automatic shutdown via interlock system; confirmation that oxygen, coal, and gas supplies have been cut off. - Maintain cooling water, seal gas, and purge gas. - After the call, restart step by step following the startup procedure. 2. Stop instrument air – the valve operates in its self-protection mode, causing an emergency shutdown of the system. - Switch to bypass/manual control to prevent overpressure and air leakage. 3. Stop the circulating water – rapidly reduce load → emergency shutdown. - Protect high-temperature equipment such as burners, pumps, and compressors. V. Steps to restore the system after parking 1. Nitrogen purging, with satisfactory analysis results: CO < 0.5%, H₂ < 0.5%, O₂ < 0.5%. 2. Check that the equipment, valves, instruments, burners, water wall, and quenching ring are free of abnormalities. 3. Establishment: Burner cooling water, quenching water, seal gas, instrument air, and circulating water are all in normal condition. 4. Maintain a slight positive pressure (0.02–0.05 MPa) in the gasification furnace to prevent air from entering. 5. Follow the startup procedure: airtightness test → heating the furnace → feeding coal and oxygen → increasing temperature and pressure. 6. Increase the load gradually, and adjust the oxygen-coal ratio, temperature, pressure, and slag discharge to normal levels. 7. Feed the qualified gas to the system. VI. Safety Precautions (Mandatory) 1. All emergency operations must be carried out in accordance with operation tickets and work orders. 2. Protective equipment and air respirators must be worn when entering the site. 3. After parking, the area must be properly purged with nitrogen before maintenance work, welding operations, or entry is permitted. 4. It is strictly prohibited to remove flanges and valves under pressure, with gas present, or at high temperatures. 5. Forcing operation under load, forced ignition, and forced slag discharge are strictly prohibited. 6. All emergency drills and operations must be recorded and archived.