IMPROVEMENTS IN FEED WATER APPARATUS FOR STEAM BOILERS."
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of the
Commissioners of Patents on the 10th May 1876. A communication from
abroad by Gaspare Mazza, of Florence, in the Kingdom of Italy.
«
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. IMPROVEMENTS IN FEED WATER APPARATUS FOR STEAM BOILERS."
According to this Invention of improvements in ejectors for steam boilers the
feed water is contained in a closed receptacle made of sufficient strength, upon the
contents of which is exerted a pressure above that of the atmosphere and preferably
equal to that of the boiler to be supplied, the pressure being in this case obtained
by putting the steam chest in communication with the upper part of the feed
receptacle.
The pressure thus exerted on the feed water facilitates the working of the injector
aided as it is by the pressure existing in the feed receptacle. It is unnecessary to
describe the arrangement of the injector, properly so called, as any ordinary injector
when suitably modified in dimensions may be made to act as a differential
injector.
With this object care should be taken to place the feed water receptacle either
entirely or partly below the feed tanks, at the bottom of the tender in the case of a
locomotive. By this arrangement, when the steam fills the feed water receptacle
and its contents are at same time discharged, it is only necessary to shut off the
steam supply and open communication with the feed tank in order to condense
the steam and establish an equilibrium of pressure in the feed receptacle and tank,
whereupon the water by its gravity and the rapid condensation of the steam will
again fill the feed receptacle in readiness to afford a fresh supply to the boiler.
The feed receptacle should thus communicate with the steam chest of the boiler
and also with the injector and feed water tank. If the injector is to be used for
feeding the boiler the latter communication should be closed, but if on the con-
trary it is only required to supply the feed receptacle the two former communica-
tions should be closed.
Another important feature in this improved differential injector consists in
the small waste pipe of the injector in communication with a receiver, provided
with a valve for regulating the pressure therein, which should be always less

page_text: than that of the boiler and at most equal to that in the feed receptacle. This
receiver may be made of very small dimensions and the valve regulating the
pressure may even be fixed on the waste pipe with the object of reducing the
capacity of the receiver in question to that of the pipe and the space sur-
rounding the jet formed by the mixture supplied by the first cone before it
enters the second one, which is in communication with the boiler. In this
differential injector the mixture is never in communication with the outer atmo-
sphere, the current in the injector being produced by the difference of pressure
in the feed receptacle and in that of the waste pipe and by the action of the steam
in the injector itself. When the injector is in working order, that is to say, when
the water and steam are in proper proportions, it tends to establish in the waste
pipe recipient a pressure corresponding to that due to the maximum tension of the
steam at the temperature of the mixture, and if the water is slightly in excess in
said recipient the pressure is maintained within the limits regulated by the valve
which allows the surplus water to escape. The addition of this waste pipe recipient
enables the boiler to be fed with very hot water.
The mixture remains in a liquid state notwithstanding that the temperature is
above 212°, inasmuch as the jet formed by the said mixture is compressed by the
pressure existing in the waste pipe recipient. With this differential injector the
boiler may be fed with water at a temperature much above 212° provided that the
pressure in the boiler and feed receptacle are suitable, and that in the overflow
recipient there is a pressure at least equal to the maximum tension of the steam at
the temperature of the mixture.