Start-Up
One of the potentially dangerous moments during start-up is the ignition of the coal or oil burners. The problem is much more complex than in regular atmospheric pressure furnaces, as ultimately the burners have to work at pressures ranging from 20-70 bar, and there are no burners that can operate properly over this whole pressure range. Where membrane walls are used, which cool very quickly in the absence of a flame, start-up burners often have to be used to cover part of this pressure range. At all times the situation should be avoided in which a mixture of a combustible gas and oxygen is present in the reactor.
After shutdown the gasifier is often nitrogen blanketed to avoid corrosion. When repairs have to be carried out inside the gasifier, one has to make sure that there are no other gases than air present. Drawing a good vacuum and breaking this with air is the best way to ensure that only air is present. This operation may have to be repeated several times to ensure that all noxious gases are removed from insulating materials, bricks, and dead ends in the plant. Even with all these precautions, air masks may be required under certain conditions.