Improvements in or relating to the Manufacture of Fuel-gas.
Year: 1892

page_text: Date of Application, 1st Mar., 1892-Accepted, 2nd Apr., 1892
COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Fuel-gas.
A communication from THE CHICAGO HEAT STORAGE COMPANY, of Chicago,
Illinois, United States of America.
ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and hy
the following statement :-
:
This invention relates to an improvement in the manufacture of fuel-gas from
coal in a so-called "producer," wherein, according to the generally stated common
practice, a coal-fire is built on a grate and, when raised to the condition of
incandescence, a fresh supply of coal is leposited upon it, such fresh supply being
repeated whenever that preceding it has been raised, by combustion, to
incandescence, the necessary supply of air being meantime passed through the bed
of fuel either in an upward, or downward or other direction.
In the manufacture of producer-gas as thus outlined, the great heat to which each
fresh deposit of coal is subjected by dumping it upon the incandescent bed in the
producer, necessarily induces sudden distillation of hydro-carbon vapors contained in
the deposited coal, which vapors escape from the producer before, they have had
time to be thoroughly gasified and are thus, in a great measure, wasted.
Furthermore, so much of the gaseous product resulting from the aforesaid
common proceeding attains a temperature so high as to tend to destroy, by its
intense heat, the metal parts (such as the coal distributer of the producer and
the conduit through which the gas is passed to the point of its utilization or
storage).
The object of this invention is to provide a proceeding whereby the aforesaid
waste resulting from the distillation of the coal deposits shall be prevented; and
whereby, also, fixed producer-gas with exceptionally high heating capacity shall be
produced having a temperature so much lower than that of ordinary producer-gus
as to reduce, materially, its destructive tendency referred to.
To these ends the invention consists, in manufacturing producer-gas from solid
carbonaceous matter by blasting the bed of fuel with air, or blasting it with air and
simultaneously forcing steam through it from below, depositing, at intervals, fresh
supplies of the solid fuel upon the said bed, retarding distillation of the hydro-carbon
vapors from the said fuel-deposits by impinging steam against them before they are
raised to incandescence, and preferably, also, preparatory to depositing fresh coal
on the initial incandescent bed, reducing the temperature of the upper surface
thereof by impinging steam against it; and the resultant gas is led off.
In the accompanying drawing is shown, by a view in vertical sectional elevation,
a gas-producer provided with means for practising the improvement.
A is a producer comprising a shell containing a grate to support the fuel Band
below which the supply of air enters through a conduit g, a steam-injector p being
provided as an air-forcing medium; and at the top of the producer is a hopper-
device C, of ordinary or any suitable construction, by means of which to supply
coal to the producer. At opposite sides of the hopper are provided steam-pipes o,
of small bore, communicating with a steam-supply (not shown). D is the outlet-
flue for the gas..
The operation is as follows:
The bed of fuel B is blasted with air from the pipe the air-blast being
continued throughout the operation of the producer, as also the steam-supply may
be used as the air-forcing medium, but is preferably employed whether so used or
not, as it very materially increases the heating capacity of the producer-gas

page_text: product. On the initial bed of fuel, after it has been raised throughout to
incandescence (though it may be before.) steam from the pipes o is admitted to
impinge against the top of the bed, thereby cooling that portion thereof and causing
the formation on the surface-portion of the bed of an ash-incrustation, or coating.
This materially reduces the conductivity of the bed-surface and, consequently, its
power of conduction and radiation; so that when a fresh supply of coal is deposited
upon it from the hopper, it will not be subjected suddenly to a heat so intense as to
generate and produce sudden distillation of the hydro-carbon vapors therefrom,
but, on the contrary, tends more gradually to heat and effect disintegration of the
Iumps forming the fresh deposit, thereby so gradually to raise the temperature of
the latter and distil therefrom the vapors, as to adapt them to be gasified before
they can escape from the producer. At the same time the temperature in the
producer is so modified by the injected steam and by the cooler surface afforded by
the ash-coating on the upper portion of the incandescent mass, that it reduces the
liability of injury to the apparatus and tends to so graduate the conversion of the
products of combustion as to reduce them to a fixed gas having a comparatively
moderate temperature.
The foregoing, involving the impingement of steam against the surface of the
initial bed of fuel, forms by preference, the first or preparatory part of the process.
The continuation of the process involves the supplying, at intervals, of fresh deposits.
of coal, each of which requires, as the essential treatment for the purpose, that steam
be impinged against it before it is heated to incandescence, since if so impinged
after it has attained incandescence, the action of the steam would be on the
incandescent fixed carbon of the coal only, because by the time the coal is in the
highly incandescent state, the volatile matter has all been released, and it is an
especial object to act upon the volatile matter contained in the coal.
The surface of the initial supply, or bed, of the fuel should not, preferably, be
below incandescence prior to the impingement against it of the steam, because in
the beginning of the process the primary purpose should be to attain the degree of
heat necessary for the action of the generator.
As will be apparent, the steam absorbs heat from the surface of the fuel-bed
during its own decomposition, which is produced by the fuel while burning, since,
as is well known, steam, while being reduced to its elements hydrogen and oxygen,
absorbs as much as the same element will again give off on combustion. Thus the
oxygen of the steam unites with the carbon of the surface coal as the latter becomes
heated by the incandescent mass below it, leaving a surface-ash which is non-
conductive of heat; consequently each fresh charge of coal dumped upon the
surface of the bed finds such surface comparatively cool, and is, furthermore,
separated from the incandescent mass by a light layer of ash, the direct effect of
such contact, and of the steamed condition of the deposit, being that the dis-
integration of the lumps of deposited coal and the distillation of the volatile
hydro-carbon contained therein are produced in a sufficiently slow manner to enable
thorough gasification of the volatile hydro-carbon to be accomplished, as the result.
of the introduction of the steam.
The supply of steam to the producer is preferably, though not necessarily,
continuous, since thereby the increments of fuel, supplied at intervals, are most
readily treated, and the steam is the more effective, being applied to the fuel while
still cool, whereas if applied to it while incandescent the volatile products would, as
aforesaid, be released and escape before the steam could act upon them, thereby
more or less defeating the object.
The air-blast and steam from below need not be interrupted while the steam
supply to the upper surface of the bed is being introduced, but both may be
continuous; and the air and steam are forced simultaneously into the bed of fuel
from below.
A further advantage that may be mentioned as incidental to this improvement is
that by preventing the escape of vapors of distillation, deposits of tar and soot in
the conveyer-flues is obviated.
'

page_text: Of course the steam employed for retarding the distillation is to be applied
always against the surface of the bed of coal through which the air finally passes,
so that if the air-blast, or air-blast with steam, were directed against the top of the
bed and drawn downward through it, the steam used for the purpose of this
improvement would be directed against the bottom thereof.
A substitute for steam, for the purpose of this improvement, would be finely
sprayed water, and the term steam employed in the claims is intended to include
such modifications, though actual steam (not superheated) is preferable to water.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to ine by my foreign correspondents, and in what manner the
same is to be performed, I declare that what I claim is :-
1-The process of manufacturing producer-gas from solid carbonaceous matter,
which consists in blasting the bed of fuel with air, or blasting it with air and
simultaneously forcing steam through it from below, depositing, at intervals, fresh
supplies of the solid fuel upon the said bed, retarding distillation of the hydro-carbon
vapors from the said fuel-deposits by impinging steam against them, and leading off
the resultant gas, substantially as described.
2- The process of manufacturing producer-gas from.solid carbonaceous matter,
which consists in blasting the bed of fuel with air, or blasting it with air an
simultaneously forcing steam through it from below, reducing the temperature of
the upper surface of the bed prior to adding fresh fuel thereon, by impinging steam
against it, depositing, at intervals, fresh supplies of the solid fuel upon the said bed,
retarding distillation of the hydro-carbon vapors from the said fuel deposits by
impinging steam against them before they are raised to incandescence, and leading
off the resultant gas, substantially as described.
3-A gas-generator comprising, in combination, a shell containing the generating
chamber provided at its upper end with a coal-feeding device and in its base with
a grate for supporting the fuel-bed, air and steam supply-pipes leading into the
chamber below the grate, a steam-supply pipe leading into the same from above,
and an outlet above the plane of the fuel-bed for leading off the resultant gas,
substantially as described.
Dated this 1st day of March 1892.
W. P. THOMPSON & BOULT,
Agents for the Applicant.