The two types of fuel gases are the producer and water gases.
Producer
It is a mixture of nitrogen and carbon (ii) oxide. it Is obtained by passing of air through red hot coke.
2C(s)+ O2 → 2CO(g)
It has a lower heating capacity due to its composition of 33% carbon (ii) oxide (very combustible) and 67% non-combustible nitrogen.
Water gas
it Is a mixture of carbon (ii) oxide and hydrogen of equal volumes. It is prepared by passing of steam through over white hot coke at a high temperature of 1000°c.
C(s) + H2O(L) → CO(g) + H2(g)
NB: Water gas is an important industrial fuel because both the hydrogen and the carbon (ii) oxide in it are very combustible.