Improvements in Bakers' Hot Plates.
Year: 1898

page_text: Date of Application, 19th Aug., 1898
Complete Specification Left, 13th May, 1899-Accepted, 1st July, 1899
Improvements in Bakers' Hot Plates..
JOHN MELVIN, St. Rollox Iron Works, Charles Street, Glasgow, Engineer, do
hereby declare the nature of this invention to be as follows:
Improvements in the construction of fuel hot plates for baking purposes, effect-
ing a more equal distribution of heat over the plate; also means for allowing
the plate to have free expansion without causing leakage of heat round its bearing
surface.
The plate rests upon a hot air chamber having 2 side and 2 end walls composed
of either iron or brick. Hot air is admitted into the chamber from an external
furnace at one end, and a flue at the other end connects to chimney; which flue
is controlled by a damper. The furnace inlet and flue outlet are both placed
at the floor of chamber causing the draught to pass across at this level. The
chamber is made sufficiently higli to hold the amount of hot air necessary to main-
tain the heat of the plate, which body of hot air is above the level of the draught
currant. As soon as the hot air enters the chamber at floor level, it rises clear
of the currant towards the flue, and spreads itself equally over the plate, resting
steadily thereon until the plate absorbes its heat. The air when thus reduced in
temperature falls to the lower part of chamber, where it is expelled by the draught
currant; while fresh heated air from the furnace takes its place.
For plates of extra length, I employ a brick or iron shield, for causing the
greater proportion of hot air to enter the chamber at a point further away from
the furnace end.
This shield rectangular in section covers the inlet at one end, and extends with
an upward inclination towards the centre of chamber; it is also narrower than
width of chamber leaving a space at both sides. The hot air after passing through
the inlet runs along the bottom surface of shield, the greater proportion passing
over the end thereof, heating the central, and further end portions of the plate;
while a smaller proportion overflows past the sides of the shield, heating the
late nearest to the furnace.
The plate has an angle iron flange rivetted on all round, the vertical web of
which lies in a trough of sand. The sand permits the plate to expand or contract,
while it seals the chamber against any escape of hot air. The trough forms part
of the top edge of chamber all round.
nah 171
B At 1000

page_text: be performed, to be particularly described and ascertained in and by the following
statement:
-
My invention refers to an improved construction of baker's hot plate, to effect
a more equal distribution of heat over the plate, also means for allowing the plate
to have free expansion and contraction without causing leakage of heat round
its bearing surface.
Fig. 1 of the accompanying drawings is a longitudinal section, and Fig. 2 a
transverse section of a hot plate constructed according to my invention.
The plate 1 upon which the goods are baked, has an angle iron rim 7 rivetted
round the bottom edge.
Bolts 9 fix one end of the plate to the furnace brick work, while the rest of
the plate is free to expand on rollers S.
The angle iron rim 7 dips into an iron or other trough of sand 10, which sand
permits the free expansion and contraction of plate, and at the same time pre-
venting any escape of heat.
The hot air from the furnace 3 passes across chamber 2 to flue 5, the draught
being controlled by damper 6; 4 is the ash pit.
Chamber 2 is made sufficiently high above the level of outlet flue 5 to hold
a storage of quiescent hot air next to the plate.
The action of the plate is as follows:-
The hot air as it enters chamber 2 from furnace 4 rises and spreads itself over the
entire surface of the plate resting quietly and steadily theron until its heat is
partly absorbed by the plate. The air thus reduced in temperature falls to
the lower part of chamber where it is expelled by the main current to flue; while
fresh heated air from the furnace takes its place.
For plates of extra length I employ one or more brick or iron shields 11 for
shielding plate 1 nearest the furnace." These shields rectangular in cross section
are narrower than the width of chamber to allow a certain proportion of hot air
to pass the sides as well as ends, 12.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed,
I claim is:
declare that what
1. A bakers hot plate having hot air chamber, furnace, and outlet flue as
described.
2. A bakers hot plate placed over a hot air chamber, in which chamber there
is an upper stratum of quiescent hot air against the plate while the active draught
or current between furnace and flue passes across said chamber at a lower level,
as described.
3. A baker's hot plate having a vertical flange round edges of said plate, dipping
into a trough filled with sand as described.
Dated this 19th dov of Mov 1800