Improved Method of Utilising the Waste Gases from Iron Smelting Blast Furnaces.
Year: 1894

page_text: Date of Application, 2nd May, 1894,
"omplete Specification Left, 2nd Mar., 1895-Accepted, 2nd May, 1895
PROVISIONAL SPECIFICATION.
Improved Method of Utilising the Waste Gases from Iron Smelting
Blast Furnaces.
I, BENJAMIN HOWARTH THWAITE of 95 Finsbury Pavement London, E.C.
Civil Engineer do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved means of utilising waste blast furnace
gases.
Existing practice either allows the gases to burn away at the open mouth of the
furnace or the gas is burnt in Lancashire or other forms of steam generators for
the purpose of generating steam.
An alternative method of utilising the gas is by its combustion in hot air
stoves for the purpose of heating the air required for feeding the air blast
tuyeres.
This invention consists essentially in the utilisation of the combustible gases for
generating power direct, by their combustion in gas engines, and in the apparatus
for preparing such gases for gas engine purposes.
The apparatus required for enabling the gas to be used for this purpose consists
of the following elements-first the preliminary air cooling apparatus, this
apparatus I prefer to construct in a special manner as follows, the gas conduit
leading the gas from the upper part of the furnace, I lead into a chamber which is
connected to a nest of vertical tubes fixed in the centre of a vessel, which may or
may not be lined internally with bricks or other heat non-conducting substances.
Around these tubes I compel the air from the blowing engine to pass; as the air
is under a slight pressure it impinges on the surface of the air tubes and abstracts
the heat from the tubes, and thus the sensible heat of the blast furnace gases is
lowered, the heat thus abstracted being recovered and returned to the furnace.
This air heating and gas cooling vessel is raised from the ground on piers in
such a manner as to enable the central nest of pipes to be rapidly and internally
cleaned, openings at the top and bottom chambers being provided for the introduc-
tion of wire or other pipe cleaning brushes.
The second element. The waste blast furnace gases after leaving the before
described vessel, are led to air cooling condensers of the usual type employed in
town gas works, the gas after leaving these condensers is led to the third element
or through a coke or breeze filled tower-scrubber, through which streams of water
are allowed to constantly permeate, effectually scouring the gas, in its upward flow,
from suspended tar and other particles; from this tower scrubber 1 lead the gas
through the fourth element or through a special form of scrubber in which the
gas is compelled to flow through sawdust or through mealy asbestos or asbestos
cloth or through fine gauge wire gauze.
From this last scrubbing process I force the gas by means of a suitable Roots
exhauster into and through a hydraulic sealed vessel to a small holder propor-
tionate in capacity to the demands of the gas engine or gas engines.
The gas treated in the manner described is quite suitable for gas engine
purposes.
Where it is desired to utilise part of the chemically heating value of the gas
for raising the temperature of the air, I lead from the blast furnace gas outlet

page_text: main, a pipe proportionate in size to the volume of gas required for power
generating purposes, this pipe I lead to the ground floor in which it dips into a
hydraulic box, provided so as to prevent the gas from escaping back to the
gas outlet main.
This gas is drawn through a set of cooling and scouring elements as already
described by means of a rotary exhauster which forces it into holder suitably
weighted for gas engine purposes. The other portion of the waste blast furnace
gases is utilised in the usual way by combustion for heating the air blast supply to
the tuyeres.
Improved Method of Utilising the Waste Gases from Iron Smelting
Blast Furnaces.
I, BENJAMIN HOWARTH THWAITE of 95 Finsbury Pavement London in the
County of Middlesex, Civil Engineer do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
This invention relates to an improved means of utilising waste blast furnace
gases.
Existing practice either allows the gases to burn away at the open mouth of the
furnace, or the gas is burnt in Lancashire or other forms of steam generators for
the purpose of generating steam.
An alternative method of utilising the gas is by its combustion in hot air
stoves, for the purpose of heating the air required for feeding the air-blast-
tuyeres.
'
This invention consists essentially, in the utilisation of the combustible gases for
generating power direct, by their combustion in the cylinders of gas engines, and
in the apparatus for preparing such gases for gas engine purposes.
The apparatus required for enabling the gas to be used for this purpose consists
of the following elements-first the preliminary air cooling apparatus, this
apparatus I prefer to construct in a special manner as follows, the gas conduit
leading the gas from the upper part of the furnace I lead into a chamber, which is
connected to a nest of vertical tubes fixed in the centre of a vessel which may or
may not be lined internally with bricks or other beat non-conducting substances
around these tubes I compel the air from the blowing engine to pass, as the air is
under a slight pressure it impinges on the surface of the air tubes and abstracts
the heat from the tubes, and thus the sensible heat of the blast furnace is lowered,
the heat thus abstracted being recovered and returned to the furnace.
j
This air heating and gas cooling vessel is preferably raised from the ground on
piers, in such a manner as to enable the central nest of pipes to be rapidly and
internally cleaned, openings at the top and bottom being provided for the intro-
duction of wire or other pipe cleaning brushes.
The second element. The waste blast furnace gases after leaving the before
described vessel, are led to air-cooling condensers of the usual type employed in
town gas works, the gas, after leaving these condensers is led to, the third element;
or through a coke or breeze filled tower scrubber through which streams of water
are allowed to constantly permeate, effectually scouring the gas in its upward flow
from suspended tar and other particles. From this tower scrubber I lead the gas
through, the fourth element, or through a special form of scrubber in which the
gas is compelled to flow through sawdust or through mealy asbestos, or asbestos
cloth or through fine gauge wire gauze.

page_text: Ninth. I prefer to drive the fan or blower by which the gas is aspired or
impelled, direct from the fly wheel of the gas engine, but of course such fan may
be driven any other way, as for instance by means of an electric motor.
Before referring in detail to the two sheets of drawings accompanying this
Specification, I wish it to be distinctly understood that I do not intend to be
confined to the exact form therein shewn, as many and varied modifications of such
designs may be made without departing from the nature of my said invention.
Referring to Sheet 1 of drawings,
Figure shews a general elevation of the plant comprising a more or less
complete assemblage of parts.
Figure 2 is a plan of same, and including in addition a vessel for holding a
certain volume of gas, such as a gas holder as well as a gas engine, and high
pressure fan.
The effluent gases produced in the blast furnace A, escape by the annular
passage B, formed by the hanging plates C, the gas flows by the main D into the
downcomer F, its flow being regulated by a mushroom valve and standard G. The
gas throws down part of its suspended matters in its downcomer, and they can be
withdrawn from the base of such downcomer by means of the water seal H and
without arresting the flow of the gas.
The gas is drawn off by means of the high pressure fan J, and driven forward
into the recuperator vessel K, by which its sensible heat is transmitted to the air
required for the blast furnace tuyeres, such air is first. led ascensionally through
the downcomer F by the pipe L, a branch of this pipe conveys the air to the
summit of the air recuperator vessel K, where it enters the collecting chamber M
and from this chamber it enters into the nest of vertical pipes N, in its descent
the air abstracts the heat from the side of the pipes, and by the time it reaches
the base of the recuperator vessel, the air attains a considerable temperature, it
finally collects in the chamber O from whence by the pipe P it reaches the tuyere
main Q and tuyeres R.
The blast furnace gases on the other hand, flow around the pipes N, and
ascend to the summit of the vessel K entering the downcomer inlet box T, from
thence the gas flows descensionally through the downcomer U, and flows into base
of coke scrubber V, ascending through the permeable mass of coke W to the
summit, and then descending by means of the main X into the secondary and
sawdust or powdered asbestos screen scrubber Y. The gas after passing through
the porous screen Y flows through a hydraulic seal Z into the gas holder Z' where
it is contained at a steady and uniform pressure suitable for working of a gas
engine Z³.
The high pressure fan is preferably driven directly the gas engine as shewn in
Figure 2, or it may be driven eventually or otherwise.
Figure 3 Sheet 2 of drawings shews an alternative disposition of the elements
of the plant constituting my invention.
The blast furnace gas is in this instance, aspired or drawn from the gas conduit 1
by the high pressure fan 2 through the hydraulic seal 3 and forced forward through
the second hydraulic seal 4, the ordinary air cooled condenser 5, the coke
scrubber 6, the special sawdust scrubber 7, and through the valve 8 into the gas
holder 9.
The fan is driven direct from the gas engine 10 which said gas engine is fed with
gas from holder 9 by means of the pipe 11.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same may be performed, declare that what I
claim is included in the following statement :—
1. For utilising gases from iron-smelting blast furnaces, the employing of special
purifying apparatus such as is herein before described in combination with internal-
combustion thermo-dynamic motors in which the whole or part of the purified
gases operate, substantially as herein before described.

page_text: From this last scrubbing process, I force the gas by means of a suitable Root's
exhauster into and through a hydraulic sealed vessel, to a small holder, propor-
tionate in capacity to the demands of the gas engine or gas engines.
The gas treated in the manner described, is quite suitable for gas engine
purposes.
Where it is desired to utilise part of the chemically heating value of the gas for
raising the temperature of the air, I lead from the blast furnace gas outlet main a
pipe proportionate in size to the volume of gas required for power generating
purposes, this pipe I lead to the ground floor in which it dips into a hydraulic
box, provided so as to prevent the gas from escaping back to the gas outlet
main.
This gas is drawn through a set of cooling and scouring elements as already
described, by means of a rotary exhauster which forces it into suitable weighted
gas holder for gas engine purposes. The other portion of the waste blast furnace
gases is utilised in the usual way by combustion for heating the air blast supply to
the tuyeres.
By the employment of my invention I am enabled to convert the heat energy
of blast furnace effluent gases directly into dynamic energy by the direct com-
bustion of such effluent blast furnace combustible gases in the cylinders of internal
combustion or gas engines.
The three essential characteristics of my invention by which I am thus enabled
to utilize the effluent gases from blast furnaces, may be thus summarised in
detail.
First. The taking off, of the gases from the blast furnace in such a way that
very little of the reduced metallic and suspended particles shall pass into the gas
downcomer.
Second. In open mouth or cold blast furnaces the effluent gases are exhausted
from the furnace in such a way that only combustible gases are removed, the
exhaust being such as to leave a slight plenum or pressure condition over the
materials in the furnace.
Third. I preferably lead the gases through a hydraulic seal which may be
placed at the foot of the downcomer pipe, and besides compelling the gases to flow
through this water I may employ a large and special hydraulic box, provided with
such a considerable area of tubes by which the gases enter the water as to make
such passage very slow indeed.
Fourth. The sensible heat of the blast furnace gases is recovered for heating
the air fed to the blast furnace.
Fifth. The gases are preferably forced or impelled, although they may be
aspired, through physical purifiers, by which the suspended particles, hydrocarbon
vapour, water vapour, and any ammonia, may be removed from such gases.
Sixth. To effect as complete a purely physical purification, that is the removable
of uncondensable or unliquefiable suspended matters from the gases, I employ by
preference a compound exhauster or blower, by means of which a pressure equal
to from 8 to 10 inches of water may be established.
The purifiers are of such a physical scrubbing character that only by means of
the establishment of a considerable pressure on the gases, will they be able to
penetrate such scrubber, and by this means any suspended matters will be
thoroughly cleared from such gases.
Seventh. The form of physical scrubbers employed are of two kinds, the
preliminary one, in which the gases are compelled to flow through a column of
coke or brushwood, and the second form of apparatus, in which the gases are
compelled to flow through a screen of sawdust or powdered asbestos, as well as
through a fine wire gauge screen, such screen of sawdust or asbestos being rapidly
removable.
Eighth. After passing through these two purifiers the gas enters the gas holder
where it is subjected to such a pressure as is best adapted to supply the gas

page_text: 2. The combination of apparatus for purifying gases from iron-smelting blast
furnaces, in which the gases pass firstly through heat-exchanging apparatus in
which more or less of their heat is transferred to the air supplied to the furnace,
secondly through one or more scrubbing towers containing coke or like material,
and thirdly through a screen or filter containing comparatively dense material
such as sawdust or powdered asbestos, substantially as and for the purposes herein-
before described.
3. The treating of gases from iron-smelting blast furnaces when specially
purified for use in internal-combustion thermodynamic motors, so as to completely
separate metallic or other pulverulent matters suspended in them, by passing them
finally through a screen or filter containing comparatively dense materials such as
sawdust or powdered asbestos, substantially as herein before described.
Dated this Twenty-eighth day of February 1895.
EDMUND HUNT,
Applicant's Agent.