The Salt Lake tribune. [volume] (Salt Lake City, Utah) 1890-current, 1913-10-24
MIXING.
BY O. w. OFT.

I against the fire, thus giving longer
interval OF time for the necessary NIX
ing. The use of a Jet Of steam for
such purpose can only be considered
| makeshift device as the steam used
must necessarily be wasted. To make
this waste as small as possible, numer~
Gus automatic arrangements have been
devised to make the Jets operative
only when fresh fuel is added TO the
fire and the volatile gases are being
driven off from this fuel
Use of Steam Jet.
A steam Jet should be used only at
such times, and unless there is some
automatic device to cut off the steam
when it is not required, the waste will
be so great that it will more than
! counterbalance any possible saving in
| fuel. In taking account of this waste,
it must be remembered that in addi-
tion to wasting steam (Which requires
the burning of certain amount or
J coal for its manufacture). more heat
is being wasted to bring the steam
from the temperature of boiling water
up to the temperature of the flue gas.
AS the heat for this purpose must also
be supplied by burning coal, 1T can be
seen how wasteful it is to keep steam
Jet on when it is not required. Where
steam jets are arranged to act as aspl-
rators and introduce additional air to
the fire through special openings Gas
is customary in locomotive practice),
they Will have still greater value in
reducing the smoke, Along this line
devices have been made for stationary
boilers so arranged that q small damp
er in tho fire door will be opened
automatically to admit additional air
| whenever the steam Jet is operating.
The opening Of the fire door to put in
n0o1 op tba CT jof md
ably arranged dashpot keeps the Jet
| turned on for short time after the
| door is closed. In conclusion 1T should
| be said that steam Jets are q make
shift and should be resorted to only
when it is impossible to obtain proper
| furnace conditions.
DOwn-draft Furnace.
Down"draft furnaces utilize re-
versal of normal direction of the gases,
| thus compelling them to pass down
ward through the bed of the fire, and
| thereby obtain excellent mixing of
these gases with the air supply. Gen
orally two CRATES are cmployed-au
upper and a lower. Coal is fed upon
the upper CRATE and the air supply is
| introduced through door above this
CRATE, with the result that the gases
distilled from the green coal are COM
| Goals and Immediately under the green
coal. As new supplies of coal are added
the cooked coal drops through the upper
CRATE onto a lower CRATE, where its
combustion is completed.
This method Of mixing the distilled
gases with the air supply by forcing
| them through the incandescent part
of the fire is also employed in the un-
derfeed stoker Here the fresh coal
is fed up through the burning coal and
at the same time air is forced through
the entire mass by means of a forced
draft. Excellent mixing of the distil-
ing gases and air supply is thus OBJ
tanned if uniform conditions of fire
and ar supply are maintained, If
holes in the fire arc allowed to occur.
the available pressure for forcing air
through the remainder of the fire is
reduced, thus decreasing its mixing
effect.