How to control the temperature of nitriding furnace in multi-purpose nitriding furnace?

After nitriding by furnace gas method nitrocarburizing, if the furnace is cooled to below 200 ℃ under the protection of ammonia gas, furnace gas deflagration will occur after the furnace cover is opened, but in different degrees.

The nitriding furnace is explained as follows:

1. The basic furnace gas of nitriding furnace is ammonia + nitrogen + hydrogen, in which hydrogen ammonia are combustible gases. When they are mixed with air to a certain proportion, they can be burned in case of open fire (including Mars) reaching the ignition temperature (above 510 ℃). They are explosive in sealed containers deflagration in open containers.

2. At this time, the furnace temperature is below 200 ℃, open the furnace cover, although there is air in, under the condition of no open fire ignition, gas combustion (deflagration) should occur.

3. However, one of the problems is that hydrogen is a strong reducing gas. During the cooling process of the furnace, it will reduce the iron nitride in the form of particles (dust) scattered in the furnace to iron powder. We know that the small reducing iron powder will be strongly oxidized heated in the air, the temperature will rise sharply to become Mars, In addition, the activated carbon powder that may be deposited in the process of nitrocarburizing will also be oxidized to Mars when encountering air. Mars ignites the "hydrogen (ammonia) - air" mixture, so there is a deflagration.

4. Prevention methods:

(1) Before opening the furnace cover, put some nitrogen into the furnace cover, dilute to drive out the combustible gas, then open the furnace cover;

(2) Open the furnace cover carefully. The operator shall be close to the furnace body, let the furnace gas escape for a while, throw the ignited paper into the furnace tank, actively ignite the remaining combustible gas, lift out the parts after being sure of safety.

The above is the multi-purpose furnace production line to introduce the relevant content, I hope to help you.