carburizing quenching furnace shutdown method is correct or not will directly affect the safety of the equipment itself and the service life of the equipment, the correct shutdown is one of the important contents of the safety operation procedures.

 1. Operating Rules for Shutdown of Carburizing and Quenching Furnace

 1) Confirm that the furnace temperature should be less than 850 ℃ and the normal, cut off the heating furnace temperature control button and the oil tank temperature control button;

  (2) Cut off the flow alarm power supply on the control cabinet;

 3) On the control cabinet, turn the rich gas and ammonia change-over switch to the OFF position;

 (4) Turn off the rich gas and ammonia flowmeters;

 Flowmeter drip (Caution 5): the solenoid valve with manual device is not allowed to be placed in the manual position under normal circumstances. Please reconfirm that all solenoid valves are in the automatic state when shutting down the boiler so that they can be automatically closed after power failure).

  (6) Close all delivery valves for ammonia and drip injection on the drip injection tank;

 (7) Switch off the heating element air switch of the heating furnace and the oil tank heating element air switch;

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 (9) On the console, press the & ldquo; front door open & rdquo; button to make sure the indicator light is on;

 (10) On the console, disconnect the & ldquo; Fire curtain & rdquo; Select switch. At this time, the fire curtain goes out and the front room burns carbon. Check whether there is leakage around the middle door and make records for adjustment after cooling.

 (11) Press on the console, & ldquo; open the middle door & rdquo; Button, confirm that the indicator light is on and keep it for 20 seconds;

 (12) on the console, press & ldquo; Close the middle door & rdquo; button, confirm that the indicator light is on, keep it for 10 seconds, and repeat, close the middle door until the exhaust gas in the heating chamber is burned out;

 (13) Close the ignition nozzle and the main valve for sealing air;

 (14) Set the lower limit pointer of the hazard protection device to 0 ℃;

  (15) Turn off the power switch of the recorder;

 (16): make sure that the fire curtain switch is turned off again before closing);

 (17) Close all gas main valves and all sub-valves on the pipeline;

  (18) insert the front door safety pin

at this time, keep the carburizing quenching furnace furnace stirring fan rotating and the cooling water of the water-cooled shaft sleeve connected until the furnace temperature drops below 300 ℃, then stop the stirring fan, the furnace temperature drops below 150 ℃, and turn off the cooling water.

 2. Explanation of Carburizing and Quenching Furnace Shutdown Operation Regulations

 Why does the furnace stop at 850 ℃? & nbsp; (1)?

if the furnace is shut down at a higher furnace temperature, due to the large amount of heat released by the combustion of waste gas during the carbon burning process, the temperature in the furnace may rise rapidly, exceeding the maximum service temperature of the furnace, seriously affecting the service life of thermocouples, oxygen probes and furnace linings. If the temperature is low when the furnace is shut down, it may lead to unclean burning of carbon black in the furnace and carbon black in the furnace, which will affect the normal production later, so it is more appropriate to choose about 850 ℃.

& nbsp; & nbsp; & nbsp; & nbsp; & nbsp; (2) Why is the oil temperature less than the normal quenching oil temperature by 20 ℃ when the carburizing quenching furnace is shut down?

mainly consider the flash point and maximum service temperature of quenching oil. if the oil temperature is high during shutdown, the surface temperature of the oil may rise rapidly when the exhaust gas in the front chamber burns, exceeding the maximum service temperature, affecting the service life of quenching oil and even causing fire. therefore, the oil temperature during shutdown shall not exceed the normal quenching oil temperature plus 20 ℃.

& nbsp; & nbsp; & nbsp; & nbsp; & nbsp; (3) Why should not the middle door be opened for too long during carbon burning in the heating chamber?

when the middle door is opened, a large amount of air enters the furnace and mixes and burns with the exhaust gas in the furnace. if the combustion time is too long and the temperature rises too fast, the furnace lining cannot adapt to rapid thermal expansion and contraction, resulting in cracking and affecting the life of the furnace lining. in addition, a large amount of air entering the heating chamber will oxidize the surface of the heating element, oxygen carbon head and thermocouple, affecting the service life of these elements.

& nbsp; & nbsp; & nbsp; & nbsp; & nbsp; (4) hazards caused by the dropping agent not being completely shut down

after the carburizing quenching furnace is shut down, if the dropping agent is not completely shut down, the dropping agent will continuously drop the furnace temperature and the source of the furnace will drop, in particular, the next time the furnace is reopened to heat up, it may cause an explosion in the heating chamber, resulting in damage to the furnace and related components.

(5) the function of the front door safety pin

carburizing quenching furnace after the furnace is stopped, the compressed air is generally closed. if the safety pin is not inserted, the front door will automatically fall and close. if the exhaust gas in the heating chamber is not completely mixed with the front chamber, it will be discharged into the front chamber, and the air, once the explosive mixing ratio is reached and an open flame is encountered, an explosion will occur in the front room. Therefore, the safety pin of the front door must be inserted after the furnace is shut down. The front door cannot be closed and the front room is open.