| 摘要 |
<p>Coal, esp. of the less metamorphised type, is heated in successive stages with the temp. increment at each stage being less than at the preceding one. At the penultimate stage the coal charge reaches the temp. at which evolution of tar vapours commences. The gaseous heating medium from the penultimate and final stages is purified before re-circulating to earlier stages. The coal is pref. heated to 350-400 degrees C in the penultimate stage, and the heating medium from the last two stages is purified by addition of air to oxidise the tar vapour, in an amt. corresp. to an oxygen content of =3% in the purified medium. Formation of coal tar deposits in the coal and gas pipes is reduced, plant output is 3 to 5.5 times greater and heat utilisation is increased by 10-12%.</p> |
