Improvements in the Method of and Apparatus Employed in the Manufacture of Coal Gas and of Compounds of Ammonia.
Year: 1890

page_text: Date of Application, 8th Mar., 1890
Complete Specification Left, 6th Dec., 1890-Accepted, 7th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Method of and Apparatus Employed in the
Manufacture of Coal Gas and of Compounds of Ammonia.
I, THOMAS HOLGATE, of 12, Hyde Park Road, Halifax, in the County of
York, Gas Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in the method of, and apparatus employed
in the manufacture of coal gas for illuminating purposes, and of compounds of
ammonia by which I am enabled to utilize the heretofore waste heat generated in
the manufacture for the purpose of purifying the crude ammoniacal liquor by
subjecting same to a gradually increasing temperature, and at the same time to
produce the illuminating gas.
Heretofore the ammoniacal liquor produced in gasworks has generally been
heated by "plant" on the same premises, (or adjacent thereto) for the manufacture
of sulphate of ammonia, strong liquid aminonia (more or less impure), and more
rarely for the manufacture of other compounds of ammonia.
The first step in these processes has been to obtain the ammonia (mixed with
other gases, called impurities, of which sulphuretted hydrogen and carbonic acid
are the chief) in the gaseous state, by heating the crude ammoniacal liquor to a
temperature of 212° F. by itself, or in contact with an alkali such as lime, soda,
or potass, using either direct fire, or steam. It was usual also to give the crude
ammoniacal liquor a preliminary heating by the waste gases from the plant."
It is also well known that by subjecting crude ammoniacal liquor to a gradually
increasing temperature, a gradually increasing quantity of sulphuretted hydrogen,
and carbonic acid, are driven off whilst the ammonia is largely retained until a heat
of 180° F. is reached when ammonia is largely liberated. This fact is made use of
to prepare a liquor suitable for removing fresh quantities of sulphuretted hydrogen
and carbonic acid from coal gas.
According to this my invention and in order to accomplish the objects as firstly
above described, by using the waste heat from the second mentioned operation and
working the two processes in conjunction with mutual advantage to each, and
although hereafter I speak only of the waste heat from distillation of ammoniacal
liquor, I may use waste heat from other sources, to supplement, or instead of, that
before named, or I may use the waste heat from retort, or boiler settings, or the
heat from coal gas in course of manufacture for the purpose of heating ammoniacal
liquor to the temperature most suited for its complete or partial purification.
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To accomplish this I use any approved form of still, for the heating or complete
distillation of the crude ammoniacal liquor, but preferably those in which the steam,
or other heating agent is brought into intimate contact with the crude liquor, on
successive trays placed in, one or more vertical stills. I may also use horizontal
stills made in the form of a Lancashire ог Cornish boiler, through which the
crude ammoniacal liquor is continually flowing, for the removal of the free
ammonia. The fixed ammonia being removed in a separate vessel containing lime
agitated and boiled by the steam and gases from the horizontal still before
mentioned.
The crude ammoniacal liquor requiring complete distillation receives a preliminary
heating by the waste heat of the gases or liquids from the same process. but pre-
ferably the heat from the waste or spent liquor should be utilized for accomplishing
this purpose, using the heat contained in the waste gases for heating to a suitable
temperature (about 180° Fahr.) fresh supplies of crude ammoniacal liquor undergoing
complete, or partial purification from sulphuretted hydrogen and carbonic acid,

page_text: The ammoniacal liquor thus purified is preferably cooled to about 60° F. before
being used in the "washers" or "scrubbers "for purification of coal gas, and this
cooling is accomplished by causing that warm liquor to increase the temperature
of other ammoniacal liquor flowing into the vessels for partial or complete
purification..
This method is to be used not only for its value in the economical manufacture or
preparation of a gas purifying agent but as a readily controllable means of
effectually condensing the waste gases from the saturator; this being accomplished
by making the containing vessels, and circulating pipes of ample capacity, and by
regulating the flow of ammoniacal liquor through them, and also by making the
outlet pipe to saturator sufficiently large, thus reducing the pressure at the outlet of
the saturator to one of not more than 0.2 lbs. per square inch. This reduction of
pressure is employed so that the operations within the saturator may proceed more
uniformly and advantageously than heretofore when this precaution has not been
taken, especially is to be noted that the sulphate of ammonia thus obtained contains
less sulphuretted hydrogen, coils of pipe either straight, circular spiral or other
shape being used to obtain the cooling and heating effects required: To render
the continuous distillation of ammoniacal liquor with lime more uniform it is
proposed to continuously feed the still with soda, potass, or other alkaline re-agent
by direct induced flow caused by the usual steam supply. It is also intended to
utilize the ammoniacal liquor undergoing distillation (after the free ammonia has
been removed) to form the solvent for the lime (calcium oxide) instead of cold
water as heretofore. The advantages arising therefrom being compactness of
arrangement, economy in fuel, and greater uniformity in "liming" than heretofore.
where a separate mixer, and injector or pump have been required, and where cold
water is used to make the lime solvent..
To accomplish the above advantages a regulated quantity of the ammoniacal-
liquor after being deprived-of its free ammonia, is diverted from-its-ordinary course
in the still, and whilst heated is passed-into-a-vessel placed close to the still, and
provided with a door through which lump or ground lime can be inserted, after
closing this door the liquor is passed into it, mixed with the lime dissolving it, and
then returned into the lower portion of the still by gravity, or preferably is agitated
by the steam supply, and carried thereby direct into the still. Instead of one such
mixing vessel there may be two or more with the steam supply near to each one,
the vessels being filled with lime alternately.
By this arrangement a relatively dilute " cream of lime" may be obtained with a
comparatively rapid flow thus preventing deposition of lime in the pipes leading
into still.
Apparatus suitable for carrying above objects and processes into practical effect
comprise in addition to the ordinary still, and saturator, a vessel in connection with
the still, which receives the spent liquor from the latter, and by a coiled or spiral
pipe to carry the same to the top of the ordinary still, the liquor being heated in
the said vessel during its passage therethrough the latter being provided with a
"sludge valve" and pipe for facilitating removal of any accumulation of lime or
sediment. A second still or receptacle is provided for receiving the hot ammoniacal
liquor undergoing purification, the gases from which as driven off are conveyed by
pipe to the saturator, and the more or less purified liquor in a heated state passes
away by another pipe to a cooling vessel below the second still or receptacle.
third receptacle or cylinder is provided, below the second still or receptacle, com-
municating by pipe with the saturator from which hot waste gases are drawn, and
heated to a higher temperature, the ammoniacal liquor undergoing purification after
having been heated at a lower temperature in a fourth and fifth vessel from which a
separate connection pipe is carried in a coiled or spiral manner through the third,
and second stills or receptacles, the hot purified liquor being carried from the second
still by a pipe to, the fourth vessel or receptacle in which it is cooled before
admission to the * washer
'OT scrubber" for coal gas purification.
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A
The purified liquor being cooled by the conduit pipe coming in contact with fresh

page_text: ammoniacal liquor about to undergo purification, the cooled 'liquor passing forward
to store tank, or gas purifying tank.
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The fifth vessel or receptacle receives waste gases from the third vessel or
receptacle when they are further cooled by the liquor undergoing purification.
Date the 7th day of March 180n
WALTER BRIERLEY,
Central Chambers, Halifax, Agent for the Applicant.
Improvements in the Method of and Apparatus Employed in the
Manufacture of Coal Gas and of Compounds of Ammonia.
I, THOMAS HOLGATE, of 12 Hyde Park Road, Halifax, in the County of York,
Gas Engineer, 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 by
the following statement:-
This invention relates firstly to improvements in the method of, and apparatus
employed in the manufacture of coal gas, and of compounds of ammonia by which I
am enabled to utilize the heretofore waste heat generated in the manufacture; and
secondly for the purpose of purifying crude ammoniacal liquor by subjecting the
same to a gradually increasing temperature. The ammoniacal liquor thus purified
to be subsequently used for the purification of coal gas.
Heretofore the ammoniacal liquor produced in gasworks has generally been
treated on the same premises (or adjacent thereto) for the manufacture of sulphate
of ammonia, strong fiquor ammonia (more or less impure) and more rarely for the
manufacture of other compounds of ammonia. The first step in these processes has
been to obtain the ammonia (mixed with other gases, called impurities of which
sulphuretted hydrogen, and carbonic acid are the chief) in the gascous state by
heating the crude ammoniacal liquor to a temperature of 212° Fahr. and upwards,
by itself, or in contact with an alkaline reagent such as lime, soda or potass using
either direct fire, or steam. It was usual also to give the crude ammoniacal liquor
a preliminary heating by the waste gases from the plant. It is also well known that
by subjecting crude ammoniacal liquor to a gradually increasing temperature,
a gradually increasing quantity of sulphuretted hydrogen and carbonic acid are
driven off whilst the ammonia is largely retained, until a temperature of 200 Fahr.
is reached when ammonia is largely liberated..
This fact is made use of to prepare a liquor relatively rich in "free ammonia,"
and therefore suitable for removing fresh quantities of sulphuretted hydrogen, and
carbonic acid from coal gas.
Hitherto the preparation of this purified ammoniacal liquor has been accompanied
by a slight loss of ammonia.
According to this my invention, and in order to accomplish the objects as secondly
above described, by using the waste heat from the first mentioned operation, and
working the two processes in conjunction with advantage to each, and although
hereafter I refer only to the waste heat from the distillation of ammoniacal liquor
I would have it understood that I may use waste heat from other sources, such as
that from retort, or boiler settings, or the heat from coal gas in course of manu-
facture, or waste steam, to supplement, or instead of that before named, for the.
purpose of heating ammoniacal liquor to the temperature most suited for its
complete or partial purification..
To accomplish this I use any approved form of still for the heating, or complete
distillation of the crude ammoniacal liquor, but preferably those in which the steam,
or other heating agent is brought into intimate contact with the crude liquor on
successive trays placed in one, or more vertical stills. I may also use horizontal
stills made in the form of a Lancashire, or Cornish boiler through which the crude
ammoniacal liquor is continually flowing, for the removal of the "free ammonia."
1

page_text: The fixed ammonia being removed in a separate vessel containing line agitated,
and boiled by the steam, and gases from the horizontal still before mentioned.
Such being the nature and object of my said invention, the following is a complete
description, of same, reference being had to the accompanying, drawing which shews
in elevation a suitable combination of "stills," apparatus, or "plant" for purposes
aforesaid.
1107
In the upper part 1 of the first vessel, or "still" the free ammonia is driven off
by heat from the crude animoniacal liquor, and is conveyed by the pipe 1º to the
ordinary saturator, the lower portion 2 of the vessel or still is where the lime,
or other alkaline re-agent-is-agitated with the ammoniacal liquor from the part 1.
At 3 is a "still" or vessel where the lime, or other re-agent, and the ammoniacal
liquor from 2 are subjected to a higher temperature, and the remains of the "fixed"
ammonia removed.
At 4 is an additional vessel for receiving hot spent liquor from 3 for the purpose
of heating the cool ammoniacal liquor to be distilled when passing through the
conducting pipe 3 to the top of the still 1. At 3b is a sludge valve, and pipe for
removing accumulation of lime and sediment from the bottom of the vessel 4.
At 5 is a vessel for receiving hot ammoniacal liquor undergoing purification, the
gases which are driven off being carried by the pipe 1 to the saturator, (not shown).
and the more or less purified liquor in a heated state passes from the bottom of the
vessel 5 by the pipe 5 to the cooler 7 below. 6 is a vessel which receives hot
waste gases from the saturator, the gases being conveyed along the pipe 6ª, to
vessel 6 and are used to heat to a higher degree ammoniacal-liquor undergoing
purification, but which-has-already been in the vessels 7, 8 the ammoniacal liquor
to be purified passing along the spiral pipe 7 through the vessels, or stills 6 and 5,
and the crude ammoniacal liquor is also carried by pipe 7 warmed in the still 8,
and heated to a higher temperature in the vessels, or stills 6, 5 as shown.
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The vessel 7 receives the lot purified liquor from the vessel 5, and is cooled
therein by the admission of fresh ammoniacal liquor about to undergo purification,
and carried in the pipe 7, and cooled purified liquor afterwards passing by the
pipe 10 to store tank, or gas purifying vessels, before admission to the scrubber
ог washer," and at 8 is a vessel which receives waste gases from the saturator
after passing through the vessel 6, and to undergo further cooling by liquor passing
through the pipe 7b to be purified, the cooled waste gases passing by pipe 9 to a
"claus kiln, sulphuric acid plant, or oxide of iron purifier. At 11 is a valve
for controlling a diverted supply of hot liquor to the lime vessel 12 and at 13 is a
door for removal of mud or sediment, the lime and hot liquor being mixed in the
vessel 12, and carried by the pipe 14 to the vessel 2, and injected therein by steam
power jet controlled by valve, the spent limed liquor being drained off by pipe 15
after passing along the pipes 16, and through the still 3.
The hot liquor undergoing purification is described, and the drawing shows it as
passing through the pipes 77, and discharged into the still 5, and flowing from
tray to tray 17, 17 with a view of exposing a large surface of the liquid, but other
arrangements would be equally effective, and may be adopted.
An alternative method would be to remove the liquid at a point say X, by means
of a "seal pipe" so that the level of the liquor in the vessel, or still 5 is maintained
about the level of the two inlet pipes 7, 76, and in that way the trays 17, 17 would
not be necessary but a larger volume of hot liquor would be retained.
The above described apparatus is suitable for carrying out my invention, but it
is obvious that the same may be varied as to curvature of the pipes and in the form
or shape of the stills without departing from the nature of the invention.
The crude ammoniacal liquor requiring complete distillation receives a preliminary
heating by the waste heat of the gases, or liquids from the same process, but pre-
ferably the heat from the waste, or spent liquor, should be utilized for accomplishing.
this purpose. The heat contained in the waste gases being utilized in heating to a
suitable temperature (about 180° or 200° Fahr.) fresh supplies of crude ammoniacal
liquor undergoing complete, or partial purification from the sulphuretted hydrogen

page_text: .
and carbonic acid. The ammoniacal liquor thus purified is preferably cooled to
about 60° Fahr. before being used in the "washers or scrubbers for the purifi-
cation of coal gas, and this cooling is accomplished by causing that warm liquor to
increase the température of other ammoniacal liquor flowing into the vessels for
partial, or complete purification, and my invention is to be used not only for its
value in the economical manufacture or preparation of a gas purifying agent but as
a readily controllable means of effectually condensing the waste gases from the
saturator of a sulphate of ammonia, or other plant; this being accomplished by
making the containing, or heating vessels, and circulating pipes of ample capacity,
and by regulating tlie flow of ammoniacal liquor through them, and also by making
the outlet pipe to saturator sufficiently large; thus reducing the pressure at the
outlet of the saturator to one of not more the-0.2 lbs. (one fiftieth of a pound)
per square inch.. ↓
This reduced pressure is employed so that the operation within the saturator may
proceed more uniformly, and advantageously than heretofore when this precaution
has not been taken; and also to deliver a more uniform stream of the hot waste
gases to the ammoniacal liquor purifying part of the apparatus.
The containing, or heating vessels employed may be of any convenient shape,
such as described, and shewn, the coils of pipes used for the circulation of liquids,
or gases may be either straight, circular, spiral or other convenient shape for
obtaining the cooling, and heating, effects required.
To render the continuous distillation of ammoniacal liquor with lime, soda, potass,
or other alkali, more uniform it is proposed to continuously feed the still with the
alkaline re-agent by direct or induced flow caused by the usual steam supply. It is
also intended to utilize the ammoniacal liquor undergoing distillation (after the free
ammonia has been removed) to form the solvent for the lime (calcium oxide) or
other alkali instead of cold water as heretofore.
The advantages arising therefrom being compactness in arrangement, economy in
fuel, and greater uniformity in feed of the alkali than heretofore where a separate
mixer, and injector, or pump have been required, and where cold water is used to
dissolve the alkali.:
To accomplish the above a regulated quantity of the ammoniacal liquor after
being deprived of its free ammonia is diverted from its ordinary course in the still I
and whilst hot is passed into a chamber, or vessel 12 placed close to the still 2, and
provided with a door 12 through which lump, or ground lime can be inserted, after
closing this door the liquor is passed into the chamber containing lime,
dissolving it.
The mixed lime, , or other alkali, and ammoniacal liquor are continuously returned
to the lower portion of the still through gravitation, or preferably agitated by the
steam supply, and carried thereby direct into the lower still 2 by the pipe 14.
Instead of one such mixing vessel there may be two, or more, with the steani
supply near to each one, the vessels being filled with lime alternately.
By this arrangement a relatively dilute " cream of lime,' or other alkali, may be
obtained with a comparatively rapid flow thus preventing deposition of solid matter
in the pipes leading into the still.
Apparatus suitable for carrying above objects and processes into practical effect
comprise in addition to the ordinary still 1 and ordinary saturator.
1st. A vessel 4 in connection with and placed near the still 1 to receive the spent
liquor from the latter.
Inside this vessel 4 a coiled pipe 3 is placed, through which cold fresh ammoniacal
liquor passes, to the top of the ordinary still 1. the liquor being heated by the spent
hot liquor during its passage through the before mentioned coiled pipe 3. The
vessel 4 is provided with a sludge valve, and pipe 3b for facilitating removal of any
accumulation of lime or sediment.
2nd. A second vessel 5 is provided for receiving the hot ammoniacal liquor under-
going purification, the gases from which as they are driven off are conveyed by a

page_text: pipe 1 to the saturator, and the more, or less purified liquor in a heated state
passes away by another pipe 5 to a fourth still, vessel, or chamber 7 below.
3rd. A third vessel 6 is provided preferably in juxtaposition with the second
vessel 5, and receives through a pipe hot waste gases from the saturator, and in
this vessel 6 is heated to a higher temperature the ammoniacal liquor undergoing
purification, being received through pipes 7 7b from a fourth, and fifth vessel
(numbered 7, 8 in the drawings) where the said ammoniacal liquor has been heated
to a lower temperature than that of the gases in vessel 6 the liquor passing
through coiled pipes into the vessel, or chamber 5.
4th. A fourth vessel 7 is provided and receives hot purified liquor from the
vessel 5, through a pipe 5 before mentioned. Inside this vessel 7 is a coiled
pipe 7 receiving a supply of impure. ammoniacal liquor, which becoming heated by
the hot purified liquor in the still or vessel 7 passes to the still or vessel 6 and is
there heated to a high temperature.
The partially-cooled purified liquor flows from the vessel 7 by the pipe 10 to a
store tank, or direct to "washers," and "scrubbers" for purification of coal gas.
5th. A fifth vessel 8 is provided receiving hot waste gases from the vessel 6 by
the pipe G which impart heat to fresh impure ammoniacal liquor flowing through a
coiled pipe 7 to vessel 6, and when cool the waste gases issue from this vessel, and
pass to any plant for utilization of the carbonic acid, and sulphuretted hydrogen
contained in them.
6th. A mixing vessel or several mixing vessels 12 are provided adjacent to the
ordinary still 1 for the reception of the dry alkali, and also of the ammoniacal
liquor, each mixing vessel being-provided with a gas tight feeding door 12" and mud
removal door 13, and connected by pipe 14 with a steam injector 14ª, the latter
drawing the mixed-ammoniacal-liquor; and-alkali-into the still 2, and agitating,-and
boiling the liquids to the required degree..
In the above description I have referred-to-the use of a saturator the latter may
be as explained an "ordinary saturator". or other form of absorbing vessel.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
I claim the vessels 5. 6. 7. 8 in combination with the appliances 1. 2. 3. 4 (and a
saturator) or their equivalents for purpose herein fully described....
Dated the on day of December 10.
THOMAS HOLGATE.
By his 'Agent, Walter Brierley,
Central Chambers, Halifax.