| The final appeal that we have launched is for funds
to help pay for the cost of the superheater tubing. What, you may wonder, is
superheating, why does Wadebridge need it and how is it
produced?
When steam is raised in a boiler it is known as saturated
steam because, through being in close contact with the water, it contains a
high proportion of water vapour. This saturated steam will then cool quite
quickly as it makes its way through the engine and can lead to the formation of
water droplets which obviously will create resistance to the movement of the
pistons and thereby reduce power and efficiency. However, if you can add
sufficient heat to convert the saturated steam into a gas, then said to be
superheated steam, this moisture content is turned into additional steam. The
temperature will be higher (as much as 800°C) which will keep the steam above
the saturation temperature all the way through the motion until it is exhausted
through the blast pipe, which will eliminate power loss from water droplets.
Furthermore, as the temperature of the steam rises it expands, which enables
more power to be developed from the same amount of steam. The additional power
developed can be as much as 25% more than with an equivalent saturated
boiler.
To superheat the saturated steam it is passed through a
chamber which dries and heats it before it is delivered to the cylinders. This
is done by making use of the flues that pass through the boiler from the
firebox to the smokebox carrying the hot gases from the fire which heat the
water in the first place. Each of these flues has a number (usually four) of
tubes inside them through which the saturated steam is passed to be converted
into superheated steam. It is these tubes that we now need to purchase for
Wadebridge, some 28 groups of four, each of 2 inches diameter,
approximately 16 feet 9 inches long and costing £5 per foot.
Please click here for a Tube Sponsorship Form. |
