千万年以来，人类的主要燃料是木头，燃烧木头的过程中，碳和氢的比率是10比1。相比较而言，煤在燃烧过程中这个比率是2比1，而石油的比率则是1比2。

Humanity's main fuel for eons was wood, which has a carbon-to-hydrogen ratio of 10 to 1 when burned; by comparison, that ratio is 2 to 1 for coal and 1 to 2 for oil.

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双交叉限位控制系统是实现燃烧炉控制的一种新型控制方法，一改以往静态“空燃比限位”的控制方式，实现动态比率限位控制。

Limit control system of expanding double-cross is a new control method, it changes control mode from former static state to dynamic one in controlling limit rate air to fuel.

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