| 摘要 |
The blanks travel in the same direction through a preheating zone as preheated air, and then move through a calcining zone followed by a cooling zone which employs a counter-current of cold air. The flue gases obtd. in calcining travel in counter-current to air (1) and form a recuperator heating air (1) before it reaches the blanks, which are heated to their ignition temp. when they reach the end of the preheating zone. In the pref. tunnel kiln, the preheating zone is fitted with two roof arches forming a channel through which gases flow to the recuperator; and air (2) heated in the cooling zone can enter the preheating zone at several points. Fresh air can also be fed into the preheating zone. Used in the mining of coal, mixts. of clay and coal are obtd. which can be moulded into high quality prods., e.g. bricks possessing high strength, plus porosity, which contain sufficient coal so they can be burned in a tunnel kiln without using any other fuel in many cases. Max. exploitation of the heat content in the bricks is obtd. without environmental pollution; The kiln has burners for use when the blanks only have a low fuel content. |
