点燃式煤气机使用煤矿煤气作为燃料(不论带或不带余热利用)就更加经济。煤气与空气混合比可在很大的范围内调配,这取决于煤矿地质的形成。煤气混合气中甲烷成份通常占30%～60%之间。尽管这种煤气混合物的低热值是非常不稳定的,但它仍可作为点火式发动机的燃料,用以发电和供热。 Ignition gas engines are more economical to use coal gas as a fuel (with or without heat recovery). Gas to air mixing ratio can be deployed in a wide range, depending on the formation of coal geological. Gas mixture of methane usually accounts for 30% to 60%. Although the low calorific value of this gas mixture is very unstable, it can still be used as a fuel for ignition engines to generate electricity and heat.