For large work pieces preheating is recommended.

用于大焊件时建议预热。

Batch and cullet preheating systems: using furnace waste gases.

配料和碎玻璃预热系统：采用窑炉废气热能。

Need not preheating, turn a few minutes to reach set temperature.

不需预热，开机几分钟内即可达到设定温度。

Preheating is required if either of these two conditions are not met.

如无法满足两个条件中任意一条，则需要进行预热处理。

Condensate from the first-effect calandria is used for preheating the feed.

一效列管换热器中出来的冷凝液被用来预热进料。