He then became a student at the École Centrale des Arts et Manufactures in Paris, France from 1837 to 1840 where he obtained a degree in mechanical engineering.

He first developed a firebox to burn poor quality coals and then around 1860 generalised his invention into a robust thermally efficient design which bears his name.

The Belpaire firebox had an improved transfer of heat and steam production due to its greater surface area at the top.

While attaching it to a boiler was more difficult due to its oblong shape, it had simpler interior bracing as an advantage.

Alfred Belpaire was one of the founders of the Congrès International des Chemins de Fer, of which he was president in 1891.