Improvements in or relating to the Manufacture of Salt, and Apparatus therefor.
Year: 1898

page_text: Date of Application, 14th Oct., 1898 --Accepted, 4th Feb., 1899
COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Salt, and
Apparatus therefor.
I, THOMAS CEATON LOWDEN, of 7, South Hill Park, Hampstead, in the County
of Middlesex, Woollen Warehouseman, 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 has reference to improvements in or relating to the manufacture
of salt its object being to provide an improved method of and apparatus for carry-
ing out the evaporation of brine and other processes in connection with the manu-
facture of salt, by which this manufacture may be more economically effected
than has hitherto been usual, and by which the manufacture of salt may be
accompanied by the preparation of valuable bye-products.
Hitherto it has been customary in the evaporation of brine to permit the steam
produced thereby to escape unused and it has further been commonly regarded as
objectionable to place over the evaporating pans, covers although the latter have
been desirable with a view to preventing the ingress of coal dust and other dirt
to the brine pans.
According to this invention the steam rising from the pans in which the brine
is being evaporated is collected preferably underneath hoods or covers placed over
the pans, and is employed in a producer-gas" generator to secure or facilitate
the formation therein of valuable bye-products such for example as ammonia,
cyanides etc.
The hot gases proceeding from the gas producer, pass through flues beneath or
tubes in an evaporating pan containing brine and in order that the heat contained
in these gases or in hot gases from any other source may be more advantageously
utilized it is preferred to form beneath the pan a double flue, that is one formed
with an upper and lower passage, the heated gas being passed along the upper and
serving to heat the brine above it, and at the same time to impart heat to a
current of air that is being passed through the lower flue.
For the further utilization of heat contained in these or other gases I provide
according to this invention a tubular framework suspended and caused to oscillate
in the brine. The oscillation of this frame-work in the brine accelerates the
cooling of the gases passing therethrough, owing to the agitation and circulation
produced in the brine, and the motion of the frame-work may serve at the same
time to sweep the salt which is being formed therein towards the sides of the pan.
The gas when cooled by any or all of the above described means to a temperature
sufficiently low for treatinent for the recovery of bye-products, may be passed into
and through a recovery plant and this it leaves containing usually a considerable
amount of water, in the form of steam. According to this invention the available
heat, still remaining in the gas and the moisture mingled therewith, is utilized for any
convenient purpose, such for example as to dry the wet salt that has been taken
from the evaporating pans, the gas being at the same time relieved of its stean
and condensed water.

page_text: The gas thus cooled and dried may be then put to any desired use or may be
burnt as is preferred in an improved furnace according to this invention, to
evaporate brine, to dry salt or for other processes related to the manufacture of
salt.
The accompanying drawings illustrate by way of example an arrangement of
and construction of apparatus according to this invention.
Fig. 1 is a diagrammatic plan showing a general arrangement of apparatus
according to this invention for promoting the generation and recovery of bye-
products and the utilization of the heat contained in newly formed gases for the
inanufacture of salt.
Fig. 2 is a longitudinal section on the line 2-2 of Fig. 1, showing details of
some of the apparatus, and
Fig. 3 a cross section on the line 3-3 of Fig. 2;
Figs. 4, 5 and 6 are plan, elevation and cross section respectively of one con-
struction of combined stirrer and heater according to this invention;
Fig. 7 is a sectional plan of improved furnace according to this invention on
the line 7-7 of Figure 8;
Figure 8 is an elevation of two adjacent furnaces partly in section on the
lines 88 of Figure 7;
Figure 9 a longitudinal section on the line 9-9 of a furnace shown in Figure 7,
and
Figures 10 and 11 are vertical section and cross section respectively of a
regulating valve for use in conjunction with the furnace.
Like letters indicate like parts throughout the drawings.
With reference first to Figures 1, 2 and 3 two producer gas furnaces are indicated
diagrammatically at A, the hot gases from which pass through flues beneath an
evaporating pan B so heating its contents.
Figures 2 and 3 illustrate a convenient construction of support for the evaporat
ing pan according to this invention.. The pan B is shown supported upon four
brick walls G each of which extends practically along the whole length of the pan.
The pan is shown shallowed at the end next to the producer and a tank C is shown
with a floor level slightly above that of the shallow end of the pan B. A short
tube or outlet A¹ for the "producer-gas" is shown opening into a chamber B
from which the gases pass under the pan B along the upper flue F. This upper
flue is separated from the lower flue F in which the air blast is heated by means
of iron plating F2 which may form a double bottom to the pan, and the air which
is heated in this lower flue may be drawn off by a pipe indicated at F3 and passed
into the gas-producer. The floor of the lower flue F may be conveniently formed
by brick arches G¹ or by the ground beneath, and the plating F is supported at
intervals along the flue, say by bricks G².
The liquid in the pan and tank is lettered H.
The pan is provided with a suitable cover or shield D, which not only
prevents the ingress of coal or other dirt to the brine, but also serves to
collect the steam rising from the brine and the air heated thereby. The
cover is preferably provided with a double roof such as that indicated in the
drawing, of which D¹ is the under part, the portion D1 serving to collect any
water which may have condensed on the under surface of the upper roof and to
prevent its return to the pan. This shield D¹ is provided with a suitable gutter
such for example as that indicated at 12 from which the water is drained by means
of a pipe communicating with say a common sump. The sloping sides of the
cover, the edges of which project beyond the walls of the pan B, further tend to
prevent the return of water of condensation to the pan, the water running down
these sides and collecting in suitable channels also leading to the sump.
The stean or mixture of steam and air collected beneath the cover D is fed
through suitable pipes by the aid of a small jet of steam or by a Root's blower or
other convenient means, into the gas producer and there serves to promote the
formation of valuable bye-products as hereinbefore stated. The withdrawal of

page_text: the steam and air collected beneath the hood or cover D by any such means
obviates the retardation of the evaporation which would otherwise be likely to
occur; the withdrawal of the steam may indeed, if carried on with a sufficient
rapidity, serve to accelerate the evaporation. The gases and the majority of the
bye-products, after passing along the flues beneath the pan B, may if sufficiently
cool be led direct to the recovery plant which is indicated at E. If, however,
it is found necessary or desirable to cool them below the temperature at which they
leave the flues beneath the pan B, they may be passed by a pump or otherwise
through a tubular frame-work or cradle suspended in the brine.
One construction of such cradle is shown in Figures 4, 5 and 6. The cradle
is composed of tubular members K suspended from swivel joints at K¹ about the
centre of which the framework as a whole is free to be oscillated by any desired
method such for example as by means of an engine. The tubes K extend prefer-
ably over substantially the whole length of the pan and are further preferably
interrupted at intervals by a box-like chamber such for example as are shown
at K. It is preferable to provide the tubular members with external ribs or
flanges which serve to increase the agitation or disturbance which their oscilla-
tion produces in the brine.
Some brine pans may be provided with furnaces beneath them in which producer-
gas may be burnt.
Such pans may be provided with cradles and hoods as described
in connection with the pan B.
Two such furnaces of the preferred construction are shown side by side in eleva-
tion in Figure 8 whilst one is shown in plan in Figure 7. The furnace consists
of a brick chamber, in the example shown approximately square in plan, into which
the gas is fed through two lateral flues L, the gas escapes from these flues through
lateral apertures L¹ in them. The cross sectional area of each flue may be
diminished as the volume of gas which it has to carry is reduced by the escape
through the apertures L'.
At the rear end of the furnace is an arch of brick or other suitable material L
extending forward about half way across the chamber and dividing the rear portion
of the chamber by a horizontal division into two. The flues L extend from front
to rear of the furnace, and some, in the example illustrated about half the total
number of apertures L', are placed beneath the brick arch L². At the forward end
of the furnace, midway between the two flues, is a grate M having a bridge M.
A brick or other screen O carried at the forward end of the arch L² and extend-
ing to the roof of the furnace chamber, serves to deflect the gases to the right and
left of the furnace on their way to the outlet flue L³. Openings or ports L* com-
municating with the upper portion of the furnace chamber are provided in the
front, and a suitable opening and door M² for permitting access to the fuel on. the
grate. An opening M³ is formed in the front of the furnace below the grate M
to allow ingress of air, and two brick screens L5 are preferably provided, one on
each side of the outlet L³, so as to facilitate the maintenance of the brick-work of
the chamber at a sufficiently high temperature.
With reference now to Figures 10 and 11, P is the supply main through which
the gases_pass to the furnace, and P the outlet communicating with, say the
passages L. Each valve consists of a sleeve Q having a lateral aperture Q to
correspond with the opening of the pipe P', the sleeve being traversed by a partition
or diaphragm Q which prevents the gases passing straight up through the sleeve
and confines it within the pipes as will be readily understood by reference to the
drawings. In order to obviate the necessity for packing, a central cup Qis
provided and may conveniently be carried by the diaphragm Q² as in the example
illustrated.
Into this central cup dips an annular flange Q4 carried by the cover Q5 of the
valve, the spindle Q being brought through the cover Q5 without the necessity of
a stuffing box and secured in a gas tight manner in the bottom of the cup Q³.
The cover Q is secured to the valve casing in a gas tight manner by bolts or any
other suitable device.

page_text: In order to keep the sleeve Q pressed sufficiently closely against the aperture of
the pipe P¹ a spring Q7 may be provided as shown in the drawings in a recess in
the casing of the valve opposite to the aperture in the pipe P¹. Oil, water or other
liquid may be placed in the cup Q3 and a gas tight joint secured at that point.
The operation is as follows:-
The pan B having been supplied with brine to be evaporated or other liquid
to be heated, and the gas generators A put into operation, the hot gas generated
is led from the opening A through the upper set of flues F beneath the pan B,
the brine or other liquid being thereby heated and the gas at the same time cooled.
Heat is also imparted through the division F2 to the cold air passing along the
lower flue F¹ in a direction contrary to that in which the hot gases are passing
in the upper flue. This hot air may be led off through a pipe such as that indicated
at F3 and utilized in any desired manner such as by serving as a hot blast for the
producers A.
The gas still hot arriving by the pipe. F+ passes through the swivel joint K'
into the tubular members K. On arriving at the interrupting chambers K², the
flow is there interrupted in such a manner as to cause the cold layer of gas adjacent
to the walls of the tubes K to be mingled with the gas which had passed down the
centre of the tubes and which had undergone less cooling, the heat of the whole
being by this means more equably diffused. The cradle and the flow of gas
through it may be so proportioned that the gas on leaving by the second swive!
joint is sufficiently cool for treatment in the recovery plant. In some cases the
cradle is divided into two or more parts each with box-like chambers and joints
at the ends, and the relative motion of the several parts arranged as may be desired.
The recovery plant may conveniently consist of one or more absorption towers of
the usual construction down which reagents such for instance as sulphuric acid
in the first tower and an alkaline solution in the second tower may flow and be
exposed to the gas which is thereby deprived of valuable bye-products. But other
means of recovery may be employed.
Reverting now to Figure 1, the gas on leaving the recovery plant
at Eis led into flues beneath a drying floor on which salt is being
dried. The temperature of the gas on leaving the recovery plant may
sometimes be as high as 100° C., and the gas is at this stage im-
pregnated with a considerable quantity of moisture. The heat contained in the
gas and moisture mingled therein is thus utilized to dry the salt on the drying
floor and the gas is at the same time relieved of its moisture, which is condensed
by the fall of temperature, the latent heat of the steam also proving of value in
heating the drying floor. The condensed water or its contained heat may be
further used in any desired manner. After having been passed beneath the
drying floor, the gas will be in most cases sufficiently reduced in temperature
and be sufficiently relieved of its steam to be taken direct to the furnace wherein
it is burnt and the heat utilized in any desired manner. The heat may however
be also employed to evaporate brine in pans B2 and the hot products of com-
bustion may, if desired after leaving the flues of the furnace be also led or pumped
through a cradle of the kind already described and immersed in brine so as to
utilize as much of the available heat as is convenient.
The tubular cradle K K2 is preferably so proportioned and weighted if necessary
that its immersion in the brine relieves the swivel joints at K₁ of practically the
whole weight of the cradle. By this means the friction at the swivel joints may
be greatly reduced and this end may be further secured if desired by providing
the joints with ball or roller bearings.
With reference now to Figures 7 to 11 gas is admitted to the passages L, pre-
ferably through the valves of the description illustrated in Figures 10 and 11
and the gas escapes from these passages L through a lateral opening L' into
the centre of the furnace chamber. At this point the gases meet with air which
has entered through the opening M2 and when commencing operations the fire in
the grate M serves to ignite them. At the later stage of the operation the

page_text: temperature of the furnace may itself be sufficient to produce combustion of the
gases without the aid of any further fuel on the grate."
The gases emerging through the apertures L' placed at the rear of the furnace
below the arch L are deflected forward by the latter, and mingling with the
gases escaping from the forward apertures L' pass upwards as indicated in Figure 9
by arrows. If at this point some of the gases remain unconsumed additional air
may be admitted through the ports L' to produce the desired degree of oxidation.
the gases meeting the screen 0 are divided into two streams one to the right and
the other to the left of said screen which subsequently unite and pass out of the
outlet flue L³.
If desired, the gas after having been passed under the drying floor or through
other drying device and so freed from its steam and cooled, may be sold or other-
wise disposed of instead of being burnt to evaporate brine. Further the heater or
cradle may if preferred be caused to reciprocate in the brine with a motion other than
oscillatory about a centre. It may for example be caused to reciprocate by tubular
rods passing through stuffing boxes in the sides of the pan, the rods serving at
the same time to convey the gas to and from the heater. Such a motion may be
arranged to fulfil the important function of sweeping the salt as it is formed
towards the sides of the pan.
Further modifications of a simple nature may obviously be made in the details
of the process and apparatus according to this invention without departure from
the spirit thereof; two important features of this invention being the cycle of
operations whereby great economy in heat is obtained by its utilization in a very
efficient manner in the various stages for the manufacture of salt; and secondly
the further economy of heat contained in the steam rising from the brine owing
to the utilization of the steam to promote or secure the formation of bye-products
in the producer.
This invention is not limited to any precise form of gas producer, evaporating
pan, flues, recovery plant or furnace or other apparatus, although it is preferred
to employ those herein before described or illustrated in the accompanying drawings
In place of this any well-known or convenient construction of apparatus may if
desired be used.
When it is not convenient or desirable to use the cradle, the heat contained in the
gas at this stage may be utilized for any convenient purpose, such as to dry the
salt or ammonia compounds.
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:-
1. In the manufacture of salt the production in a gas-producer of ammonia or
of cyanogen compounds by the introduction into the producer of steam given, off
from the brine.
2. In the manufacture of salt in which brine is evaporated by the heat radiated
from a gas-producer or by the gas therefrom the production in the producer of
ammonia or of cyanogen compounds by the introduction into the producer of steam
given off from the brine.
3. In the manufacture of salt the combination with a gas producer and an
evaporating pan heated thereby or by the gases therefrom of recovery plant to
retain bye-products formed by the admission to the producer of steam given off
from the evaporating pan.
4. In the manufacture of salt the combination of a brine evaporating pan two
flues or sets of flues one for hot gas and the other for air or other fluid so disposed
that the gas in the one serves to heat the contents both of the pan and of the
other.
5. In the manufacture of salt the combination with a brine evaporating pan
of a tubular or other heater capable of reciprocation in the brine for the purpose
described.

page_text: 6. For use in the manufacture of salt the heater and stirrer having interrup-
tion chambers such as K² substantially as and for the purpose described or illus-
trated in Figures 4, 5 and 6 of the accompanying drawings.
7. In the manufacture of salt the combination of a gas furnace substantially
as described and illustrated in Figures 7 and 8 and 9 of the accompanying
drawings with a brine evaporating pan.
8. In the manufacture of salt the combination with a brine pan heated by a
gas furnace of a valve substantially as described and illustrated in Figures 10 and
11 of the accompanying drawings.
9. In the manufacture of salt by producer-gas the combination with a recovery
plant of a salt drying device which is heated by the mixture of producer-gas and
steam delivered from the recovery plant.
10. In the manufacture of salt a method or process comprising the following
steps the evaporation of brine by the cooling of the hot gas from a gas producer
the utilization of steam from the brine for. the formation of bye-products in the
gas-producer the recovery of the bye-products from the gas and the drying of salt
by the hot mixture of gas and steam delivered from the recovery plant. for the
purpose described with or without the evaporation of brine by the combustion of
the gas freed from steam and bye-products.
1021