What is Lancashire boiler?

Answer 1

The Lancashire boiler comprised a large steel shell usually between 5 - 9 m long through which passed two large-bore furnace tubes called flues. Part of each flue was corrugated to take up the expansion when the boiler became hot, and to prevent collapse under pressure. A furnace was installed at the entrance to each flue, at the front end of the boiler. Typically, the furnace would be arranged to burn coal, being either manually or automatically stoked.

The hot gaseous products of combustion passed from the furnace through the large-bore corrugated flues. Heat from the hot flue gases was transferred into the water surrounding these flues.

The boiler was in a brickwork setting which was arranged to duct the hot gases emerging from the flues downwards and beneath the boiler, transferring heat through the bottom of the boiler shell, and secondly back along the sides of the boiler before exiting through the stack.

These two side ducts met at the back of the boiler and fed into the chimney.

These passes were an attempt to extract the maximum amount of energy from the hot product gases before they were released to atmosphere.

Later, the efficiency was improved by the addition of an economiser. The gas stream, after the third pass, passed through the economiser into the chimney. The economiser heated the feedwater and resulted in an improvement in thermal efficiency.

One of the disadvantages of the Lancashire boiler was that repeated heating and cooling of the boiler, with the resultant expansion and contraction that occurred, upset the brickwork setting and ducting. This resulted in the infiltration of air, which upset the furnace draught.

These boilers would now be very expensive to produce, due to the large amounts of material used and the labour required to build the brick setting.