IMPROVEMENTS IN GENERATING AND APPLYING HEAT IN EVAPORATING SALINE AND OTHER LIQUIDS IN THE MANUFACTURE OF CHLORIDE OF SODIUM AND OTHER CRYSTALINE SUBSTANCES, AND FOR OTHER HEATING PURPOSES, AND IN APPARATUS CONNECTED THEREWITH
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by William Bull at the Office of
the Commissioners of Patents, with his Petition, on the 4th
December 1875.
I, WILLIAM BULL, of Knight's Hill, Lower Norwood, in the County of
Surrey, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN GENERATING AND APPLYING HEAT IN EVAPORATING SALINE
AND OTHER LIQUIDS IN THE MANUFACTURE OF CHLORIDE OF SODIUM AND OTHER
CRYSTALINE SUBSTANCES, AND FOR OTHER HEATING PURPOSES, AND IN APPARATUS
CONNECTED THEREWITH," to be as follows, that is to say :-
This Invention relates to improvements in generating and applying
heat for evaporating brinc and other liquids in the manufacture of
chlorides of sodium or other substances, and for other heating or
evaporating purposes.
I place the brine or other liquid to be evaporated in one or more
evaporating pans, which may be of the ordinary form or not as circum-
stances may require; by preference I use three of such pans placed side
by side, or one large pan divided into three compartments. Under the

page_text: centre pan or compartment I form a chamber or flues, in the fore part
of which I place the furnaces, and beyond the furnaces transversely a
boiler with multitubular flues running horizontally through the same
for the passage of heat from the furnaces to the chamber or flue space
beyond. I make or line the floor and sides of this chamber with any
suitable non-conducting concrete or other material to prevent as far as
possible the loss of heat from radiation. Under one of the side pans or
compartments I also form a chamber or flues protected in a similar
manner, both of these chambers being made as nearly air-tight as possible,
and under the other side pan or compartment I form a chamber also
similarly protected and made as nearly steam-tight as possible, or I form
this pan or compartment with a double bottom. Under the centre pan
or compartment I place the boiler before mentioned transversely so as
to divide the open space under such pan into fore and aft heating
chambers. The space before the boiler (which may be from 10 feet 1
to 15 feet from the front) forms the furnace in which the combustion
chambers herein-after described are placed.
The brine or other liquid to be evaporated I prefer to supply to the
pans or compartments from a heated or other receptacle, in and from
which the flow can be regulated, so as to keep pace with the evaporation.
I also prefer to cover the pans and cause dry or heated air to circulate
through the space under such covers to raise and carry off aqueous
vapour from the evaporating surface or surfaces, and I utilize part of
the waste heat from the heating chambers under the pans for this
purpose. I make these covers moveable or to open and close as required. ;
The heat is generated and applied under the pans or compartments as
follows, that is to say:-The furnaces are provided with combustion
chambers formed with an open grate or fire-bars at the bottom, and
enclosed at the sides and roof with fire-brick, or lined with other good
fire resisting material, and in which chambers incandescent heat is
obtained and maintained. These furnaces are closed in the front and
fitted with fuel holders, from which small coal or other fuel can be
supplied to the combustion chambers by hand or machine power. Under
the fuel holders and above the fire-bars there is an opening closed with a
rising and falling door through which air can be admitted and clinkers
withdrawn when necessary.
Under the combustion chambers ash-pits are provided, divided into

page_text: or a grate by which air from the lower compartment to the upper one
can be admitted or shut off and regulated as required, and by which
plate or grate a hot-air chamber is formed, through which the air heated
as much as possible by waste heat before it comes into contact with the
carbonaceous matter in the combustion chamber passes. The fuel is
first deposited from the fuel holder upon a plate or shelf in the fore part
of the furnace where it is heated by the radiated heat from the interior
of the combustion chamber nearly to ignition temperature, the hydro-
carbonaceous gases or crude products of combustion given off in the first
instance pass through the combustion chamber, where they are ignited
and become incandescent by the action of the great heat maintained
therein.
As the fuel is consumed in the combustion chamber the cinders and
ashes fall from the fire-bars through the hot-air chamber on to the plate
or grate before mentioned. By partially opening this grate the ashes are
discharged into the space below and withdrawn separately, while the
cinders (if any) remaining on the grate by further opening or tipping it
are also afterwards discharged into the space below, whence they may
also be withdrawn separately and transferred to the fuel holder. The
combustion chamber is placed in the front portion of the furnace
(forming a kind of furnace within a furnace) and extending about
(more or less) of the length or distance through the furnace, where the
former opens into the latter, so that the heat generated in the former
is diffused through the latter in part directly, and in part by radiation.
The main body of the heat flashes from the openings at the ends of the
combustion chambers through the tubes in the boiler, and thence along
and under the centre pan to the back end thereof, whence it traverses a
suitably formed and lined passage opening into the space under one of
the side pans through which the heat passes from back to front and
thence through a air heating battery into a chimney or shaft.
The third pan or compartment is heated by the steam generated in the
transverse boiler. The steam from this boiler is conducted by a steam
pipe opening into the steam tight space formed under this pan as before
mentioned; the floor of this steam space inclines to the mouth of the
steam pipe, so that the hot water from the condensed steam may flow
back into the boiler as fast as condensation takes place, the boiler being
thus constantly refed with its own hot water a few degrees only below
the boiling point.

page_text: For making good any waste of water the boiler is fitted with a self-
acting feed pipe and supply tank. The pan or pans thus formed fitted
and placed, and being heated by one set of furnaces only may be worked
at varying temperatures for producing "fine," "common," or coarse.
grained crystals of chloride of sodium separately or simultaneously, while
labour and fuel are thereby saved. The hot air chambers are supplied |
by air heated by passing through the battery before mentioned, and a
quick or slow draught in the combustion chambers is obtained by
placing a screw or other fan in the bottom or other part of the chimney
or shaft, and driving it by any suitable power, the fan is thus made to :
operate by induction instead of by blast. The heat is thus capable of -
being kept more uniform, and is "drawn" forward in greater or less.
volum as the temperature of the brine or other liquor in the pans may
require.
The pans or compartments are placed at one level, and connected at
their fore and aft ends respectively by pipes or troughs, upon which pipes
or troughs suitable stops or valves are placed for connecting the pans or
compartments, or disconnecting them as required. By opening these
valves a circulation of the brine is effected and a mean temperature in
all the pans obtained. This circulation results from induction as by the 2
mode of heating the pans herein described a current is induced from
the side to the centre or furnace pan. The brine or other liquor can be
raised to any required temperature, and the pans be worked at a uniform
heat throughout, a matter of great importance in the manufacture of
crystals of regular size and texture. In order to insure this uniformity 2
of temperature I fit the pan or pans with a bell thermometer in which a
a column of mercury is caused to make and brake contact with the ends
of two platinum wires the ends of which are placed about 5° (more or
less) one above and one below the other by the thermometer scale, the
mean height being the temperature at which the pans are required to be g
kept. One of these wires I connect to the positive pole, and the other
to the negative pole of a galvanic battery; upon the positive wire I
place a "sharp" bell, and upon the negative wire a "flat" bell; in case
the brine or other liquor becomes too hot contact is made by the rising
mercury with the positive wire, and in case the brine or other liquor s
gets too cold the mercury falls and breaks contact with the negative wire.
The ringing of the sharp or flat bell apprises the fireman of the condition
of the pans, and enables him to regulate the damper, fan, and feed.

page_text: mechanism as required. The ends of the wires are capable of being
adjusted on the scale to work the bells for any required heat.
The combustion chamber, furnaces, and mode of generating incandescent
heat may be applied for other evaporating or heating purposes, and the
heat be regulated as herein described. For indicating and regulating
the heat in such furnaces I introduce and fix a bell pyrometer therein,
and cause two finger pieces on a reciprocating pyrometer rod to make
contact with the opposite poles of a similar battery, the connecting
wires of which are similarly fitted with sharp and flat bells, and by
suitable mechanism cause this rod to open and close a valve for
admitting hot or cold air to the furnace in greater or less volum as
required.
In the manufacture of fine salt I pass the brine through a filter or
other purifier to cleanse it before it is supplied to the pans.