US1326414A - Process and apparatus for reclaiming waste products in the manufacture of wood-pulp. - Google Patents

Description

H. K MOORE AND J. T. QUINN. PROCESS AND APPARATUS FOR RECLAIMAING WASTE PRODUCTS m THE MANUFACIUREOF WOOD PULP.

APPLICATION HLED HJB. 13. I918.

Patented Dec. 30, 1919.

HHHHHHHHHI- UNITED STATES PATENT orrron.

HUGH K. MOORE AND JOHN T. QUINN, OF BERLIN, NEW HAMPSHIRE, ASSIGNORS TO BROWN COMPANY, OF PORTLAND, MAINE, A. CORPORATION OF MAINE.

: PROCESS AND APPARATUS FOR RECLAIMING WASTE PRODO'C'IS IN THE MANUFACTURE OF WOOD-PULP,

To all whom it may concern:

Be it known that we, HUGH K. Moons and JOHN T. QUINN, citizens of the United States, residing at Berlin, in the county of Coos and State of New Hampshire, have invented new and useful Improvements in Processes and Apparatus for Reclaiming Waste Products in Y the Manufacture of Wood-Pulp, of which the following is a specification.

This invention has relation to the recovcry of the mineral or inor anic content of the liquor employed in the igestion of raw material in the manufacture of cellulose fiber, although it is capable of Wide application in various arts.

In order that the nature of the inven- .tion may be understood, we shall describe it particularly in relation to the manufacture of sulfate pulp or soda pulp, in which,

after the raw material has been subjected to a process of digestion, the fiber is separated from what is termed the black liquor", the latter containing various valuable inorganic products which it is desirable content recovered in its desired condition.

Said Letters Patent show how the principles of Stefans law may be applied to the evaporation'of the water and the recovery of the soda from the blackliquor resulting from the so-called sulfate process. This law'reduced to simple terms may be stated as follows: B. T. U. radiated per square foot of radiating surface per. minute: 2.6 8X i0 (T -'"-T,) when T is the absolute temperature of the body which radiates heatand. T, is the absolute temperature of the body to whichheat is radiated. It is evident that, if'one can reduce the amount of heat. required to be radiated, one will t a direct benefit due to maintaining a big er average temperature in the. radiating body which must necessarily lose in temperature Specification of Letters Patent; Patented-Dec, 30, 1919; Application filed February 13, 1918. Serial No. 216,998. l

as it radiates heat. This increases the heat.

radiated in a given space of time from-the same surface area,- or, to state it differently,

one can cause the radiation of a reater quantity of heat from a smaller ra iatin eign fuel introduced into the furnace and by the combustion ofthe combustible content of the black liquor, it having been found up to that time that the introduction of a foreign fuel, such as gas, oil or powdered or pulverized coal or coke, was necessary for the production of the requisite radiant heat. It was the intention, as expressed in the Letters Patent referred to,

-- by the employment of a blast of air to atomize the fuel, and also by a blast of air or steam to atomize the lignin'or black liquor so as to reduce it to the finest ossible particles and thereby to increase t e evaporating and radiating surfaces of the particles of black liquor, but this was done, as stated,

by pressure or bycontact with a blast of alr or steam external to the particles themselves. liquor, at the time of its introduction into the furnace, is in a high viscous state due to its preliminary partial e'va oration and concentration, the particles t ereof when subjected to a blast of high velocity, are necessarily large, relatively speaking, because of their hlgh viscosity and great cohesive properties, and they consequently acquire a high velocity, due to the air blast, through the space in which they were subjected to the radiant heat. Because of the.

rapidity with which these particles are projected'through the heating space, they are Inasmuch, however, 'as the black subjected in transit for only a minute length of time to radiant heat, and, because of their globular or compact condltlon, they acquire ess heat by convection than if they were sub-divided into small particles. Furthermore, because of the'relatively heavy weight ofthe relatively large particles thus atomized by a blast of air, their velocity is necessarily hio'h throughout their travel. In particles of the same material, the inertia sistance of the air is as the square of the is as the cube of the diameter while the rediameters are approached, the resistance,

- due to the square of the diameter, overtakes and exceeds the inertia, which is as the cube of the diameter. Thus, as the diameter of the particles is decreased, the resistance of the air rapidly decreases the velocity thereof, and the distance which they travel. If the sub-division of the particles is continued, a particle may be obtained so fine that, while it will start with an initial,

high velocity, this velocity will be almost instantly checked, with a result that the particle might be said-to float inthe air. Furthermore, when the particles of relatively large size and heavy weight are subjected to both'heat of radiation and heat of convection, although the peripheralportions of the particlesmayhave had the water evap-. .orated therefrom'andv the carbonaceous portions 'partiallycha'rred, there is contamed in the middle of the particles a pasty mass through which jthe heat has not penetrated a loss of radiant. heat which might have been obtained in the particles had they all been brought to a radiant conditionduring their flight from the nozzle to the floor, or

which might have been obtained if those which were brought to a temperature where they would radiate heat to a considerable extent in their transit were possessed of a greater. radiating surface. a

' In the process and apparatus disclosed in the Letters Patent previously mentioned, the

means of sub-dividing these particles was, as previously Stated, entirely external. In carrying out said process, there were employed, in practice, first, Various kinds ofv can be sub-divided to such an extent that mechanical nozzles in which the centrifugal force of one portion of the liquor rotating in contact with another portion of the liquor revolving in the opposite direction tended to strip the entire liquor into, fine particles;

and, second, fiat nozzles designed to subdivide the liquorinto a spray by a thin knife-like blast of airat high pressure and high velocity. These nozzles, while they did not meet'the optimum conditions, yet

' were sufficiently successful that the whole operation of an industrial plant was based upon their use. Nevertheless, as heretofore explained, though the particles produced by such nozzles were comparatively minute in r relation to drops, they were relativelv large in comparison with particles which would be. practically all surface and no volume.

weenie Inasmuch as these particles were so relatively large, the heat of convection and what radiant heat would ordinarily come from the walls of a furnace, sublimed soda salts, and burning particles of black liquor, were not sufficient to evaporate these particles in their entirety while in transit, and they arrived at the furnace floor in a more or less wet or pasty condition and tended to smother the fire thereon. In order to overcome these difficulties, an extraneous source of heat had to be supplied, and it was derived from the combustion of powdered coal, oil, or. gas. In the use of gas, for example, the radiant particles were composed of illuminants, which, heated to a high temperature by the burning gases and also burning themselves, added enough additional heat so that the particles of liquor would reach the furnace fioor in a condition not to blanket the fire, and the operation therefore could be continued. A plant, running successfully under these conditions, has been operated for several years. 2

Inasmuch as the'blast of air,'in order to properly disintegrate tha black liquor, cannot practically be over 6/1000 of an inch in width, it will be readilyseen that a slight wearing of theseair nozzles greatl reduces the efliciency-of the operation. Tliat is, as the air nozzle is greater in width, the tendency .becomes greater to blow the black liquor in mass away r atherv than disintegrate or atomize it. In the so-called sulfate proc- Y ess, the dry residue from the black liquor on evaporation contains somethin over 5,000-

B. T. .U. 'pengound. In the su fite process, the dry res ue contains something over 6,000 B. T. U. per pound. If, then, 2 pounds of-black liquor containing 50% water werethey will acquire a large part of the heat required for evaporation from the surroundinghot gases, the amount of radiant heat which will have to be added thereto may be very small.

The object of the present invention, in contra-distinction to the process disclosed in. said patent, is: first, to eliminate the necessity of using a foreign fuel for bringing about the combustion of the concentrated or partially evaporated black liquor; second, to increase the capacity of a furnace of a given size and also to prevent losses due to the exterior radiation and conduction of heat from the furnace walls; third, to insure a greater evaporation of the Water contained in the particles of black liquor during their transit by convected and radiant heat, there: by to bring about the charring and combusi tion of the carbonaceous portions of the black liquor contained in the particles while in transit, and thus to furnish additional radiant heat for the eva oration of subsequent particles of the b ack liquor which have not reached the radiant sta e; fourth,

to reduce the weight of the partic esof black liquor and to increase their surface area,

' thereby to insure their heating by convec tion and to reduce the velocity of their travel through the heated ases in the furnace; and, fifth, to insure t at the alkaline efiiuent of the furnace is maintained higlr in sodium sulfid. v

In explanation of the manner in which these objects are attained, we avail ourselves space it previously occupied; for example, a

pint of water, roughly speaking, when transformed into steam at 28 inches vacuum, occupies 350 cubic feet or 21,000; times the space it occupied as water. We may utilize both of these principles in securing the desired results in the practice of our invention, by preheating the liquor to a high tern perature while maintaining it under pressure greater than the vapor pressure at that temperature, and then liberating it in a stream in a furnace, whereby we obtain a double explosive efi'ect which dis'-- rupts the li%uor internally and disinte rates it into the nest possible particles. 5 an illustration, let it be assumed that the liquor is heated to a temperature of 350 F, while maintained at a pressure greater than its vapor pressure, and is then suddenly liberated in the furnace in which there is (for example) a partial pressure corresponding to 28 inches of vacuum (for instance an atmosphere of 93-1/3% inert gas, and 0-2/3% steam) under these conditions there would be an explosive action in-the liquor due to the instant reduction in tem erature from 350 F.'to 212 F. at atmospheric ressure, and the further reduction to 100 due to the partial vacuum. While it may now be possible or practical to store sufficient heat to change al of the water of the black liquor into steam, it is practical to raise the liquor to ,a sufiiciently high temperature while holding it under great pressure, to cause the transformation of one-fourth or to one-third of such water into steam with the resultant explosive action. B generating a high explosive force in the liquor and injecting the liquor into the furnace, irres ective of a par: tial pressure therein -(whio may or may not exist, although we have reason to assume a partial pressure), the explosion which occurs causes the disintegration of the viscid material into minute particles, and thetearing aplart of the lignin or cementitious cement t ereof, so that, roughly speaking, the particles are very light and are practically all surface. Consequently, although the particles start at high velocity in the furnace, their velocity is almost instantly checked and a large part thereof may be said almost to float in the air, and hence not only is the water evaporated, but the particles are charred, and the carbonaceous content is charred and actually consumed by combustion while in transit, thus furnishing a high degree of radiantheat for the following particles of black liquor. Under these conditions, we have eliminated the necessity of using a foreign fuel, as the combustion of the pombustible content of the black liquor in transit, and, as it reaches the furnace floor, furnishes-the heat of radiation and convection for the evaporation of the water content.

, In carrying out the invention, we may use 1 5 is a stora e receptacle for finely pulverized salt ca e which connects through removable diaphragms 6 and pipes 7 with the agitator tank 4. The diaphragm 6 is re movable and may be made of various sizes so that the salt cake, which is to be mixed with the liquor, shall correspond to the amount of liquor coming from storage tank 1. From the mixer tank a the mixture is drawn through pipe 8 by a pump 9 and delivered through pipe 10, and T 11, pump 12, by which said black liquor and salt cake are forced through pipe 13 into coil 14 of the heater 15, and thence through the pipe 16 to header pipe or manifold 17 having valves 18 leading to pi es 19 projected into the furnace. The hea or 17 is also, by means of an extension 20, connected with pump 21 and pipe 22 (having a check valve 221, if desired) to T 11. Steam is introduced into the chamber in the heater through a pipe 23 leading from a steam main not shown. The

drip from the heater 15 is delivered through pipe 24 to a trap 25 from which the condensed water is discharged. The pipe 19 from the manifold 17 is projected into the door of the furnace 26 which heats the boiler 27. The particles of the black liquor, which is atomized into a spray indicated at 28, are largely consumed while in transit, while larger unconsumed but more or less charred particles are deposited on the pipe 29 on the sloping floor of the furnace where they are completely consumed. The consumed gases and fine solid particles which float in the furnace gases are carried through the lines of boiler 27 to a stack 281 through fan 291, and pipe 30, Where they v are either switched directly to the atmosj phere through the extension 31 of pipe 30, or into a .Oottrell precipitator 32 where the particles are precipitated into a hopper 33 while the gases escape to the atmosphere through pipe 34. The smelted efiiuent is delivered from the furnace'through spout 35 into agitator tank 36. As described, in the previous Letters Patent, hereinbefore referred to, air at 3 to 5 pounds positive pressure is delivered through pipe 37 into the fire chamber below the spray to support the combustion. It may also be stated that the black liquor, which runs into the storage tank 1, may be obtainedin a partially evaporated and concentrated viscous condition from the evaporating system A, A, here represented conventionally as twoefi'ect.

The operation may be brie-fly described as follows:

After the liquor has been mixed with a finely divided salt cake in mixing tank 4, it is necessar to keep the liquid in very rapid circulation to maintain the salt cake in suspension,'for it must be realized that, after the liquor' has been concentrated to about a 55% solution, it will not then dissolve the requisite amount of salt cake. Consequently all means for feeding the black liquor employed after the salt cake" has been'added must be such as'to prevent the salt cake from settling. This is accomplished in the present case by keeping it at high velocity during the remainder of its travel, and by passing it through the coil in the heater, wherein the centrifugal force-of the liquor in traversing the coil and its constant change indirection keep the mixture well stirred so that it becomes rapidly heated and does not stick to the wall of the coil or polymerize by prolonged contact with a given heat surface. Pump 9 and pump 12 are shown in the drawing in place ofa two-stage or threestage pump, in order that the operation may be more clearly depicted. In practice, however, pumps 9 and 12 are preferably built as two-stage or three-stage pumps.

Pump 9, in delivering the liquor through pipe 10 into pump 12, builds up the required pressure; first, to maintain the velocity in the liquor coil Id, and, second, to maintain a pressure far above the corre-. sponding vaporizing pressure of the liquid at the temperature to which the steam entheaters tering at pipe 23 would heat it. For instance, if we desired to heat the liquor to 335 R, we should maintain at all times on manifoldjli' as shown, goes through a pipe 20 to pump 21, thence through pipe 22, into the T 11, between pumps 9 and 12, or between the first and second stageof a twostage pump. The drawing here illustrates only one of the manymethods in which this operation can be accomplished. For instance, pump 21 might 'be inserted in pipe line 16, or pump 9 might discharge into the pipe 20, thereby lowering the temperatures of the liquor passing through the pipes 21, 22, and T 11 to pump 12.

It will be seen that, by passing the liquor through the coil in the heater 14 and letting itescape through nozzle 19 into a furface, containing the hot and dry atmosphere, the liquor is automatically blown, exploded or disintegrated into the most minute particles, according to the principles hereinbefore stated. Pipe 19 is formed or I provided at its end with a nozzle which is formed with a narrow elongated delivery port so that the explosive actlon plractlcally takes place at the nozzle. This w ole process, to secure thebest results commercially, requires the employment of a Cottrell or electrostatic. recipitator, since the initial velocity ofthe fine particles of liquor is checked almost instantly and the particles more or less float in thefurnace -gases, a

' greater proportion of them being so small and light that they float in the furnace gases t rough .the boiler and exhauster and would eventually be lost in the atmosphere. This. precipitator enables us 'to carry out this process as it enables us to recover most of the soda in the fine atomized particles which tend to float away. In this connection it may be observed that the preheating 'ofthe liquor and its disruption as herein stated and the elimination of foreign .fuel

reduces greatly the gas flow: through the boiler tubes and the Cottrell precipltator.

This is advantageous in that it makes for a more efiicient precipitation of the particles of the soda content and diminishes the loss of heat through the furnaces.

In the process above described, it will be seen that the heat, which may be added to the liquor, is dependent first upon the temperature of the steam, and, second, upon the pressure, and requires care in the number of and the selection of the design and speed of the pumps employed. In order to over- --'come the ditficulties in pumping this alkaline liquor, we prefer to use high speed high pressure pumps having a lon stufiing box containing a antern gland. nto this lantern gland oil or'water is preferably introduced to prevent the caustic liquor from injurin the packing. Of course in this case the use of brass is not allowable.

Referring again to the drawing, the liquor which 'comes from the manifold 17 through the pipe 20 to pump 21, pipe 22, is pumped through 21 (which is used more as a circulating ump than for any other reason), and at the 11 it meets the colder liquor coming from pump 9, so that at the reduced temperature it passes through pump 12 through the heating. coil where it is raised to the final desired temperature in pipe 16, In actual practice, the higher the temperaure which can be given to this liquor the better are .the results secured in the furnace; first, because less heat need be furnished from the furnace proper.to efiect the evaporation of the water in the liquor, and, second, because of the greater ex losive effect of the resultin hot liquor. his liquor, when it enters t e furnace, immediately gives up its stored up heat, and liberates a large part of its steam without any extraneous heat, the remaining water being evaporated by the contact of the hot gases with the particles and by the radiant heat from the walls of the furnace and the minute burning particles, some of which take fire within a few inches from the nozzle. The result is that practically all of the particles, as nearly as can be observed, take fire while in transit, and many of them have their combustible matter entirely consumed before they land on the furnace floor. The largest ones, however, may land on the pile 29, which, however, instead of being more or less of a pasty mass, is a live bed of hot combustibles. This breaks off or slumps forward from time to time, and forms a more or less charcoal-like bed through which the. smelted inorganic matter runs to the spout causing the sulfate content to be reduced to sulfide very much the same as if it were passed through a bed of charcoal.

It will be seen from the foregoing that, first, having supplied a large part of the heat from an outside source, second, having eliminated the air blast necessary to atomize the liquor, third, causing the burnin of the fine atomized particles in transit,.a-n fourth, obtaining more heat for evaporation by. means of convecti0n,-we have enr ly dispensed with the necessity of employing a foreign fuel and the air required to burn the same. W e should, however,'not' regard, it as a departure from the invention if the ractice of our process were accompanied y the combustion in the furnace of a seous or other fuel.

n the process and apparatus described therein, and

in the previous Letters Patent, herein referred to, the volume of combustible gases was a great deal larger than the volume of the combustible gases in the present case and consequently caused an increased flow through the boiler tubes. By cutting down the products of combustion, the velocity of the gases and products of combustion through the boiler tubes is slower, with the consequent saving of heat, or the prevention of the loss of more heat through the flue gases. Furthermore, as it was not always possible in the previous process and apparatus to maintain in their entirety the predetermined oxidizing and reducing zones, the large excess of air used to burn the combust1ble gases some times acted as an oxidia mg agent in a detrimental oxidation of the sodium sulfid to sulfate.

Summarizin the foregoing, we mix the by means of pumps, heat it while under pressurein a heating coil, discharge it into the furnace under pressure, circulate the remainder of the liquor which does not go in the furnace back to the pumping system, keep the rapid circulation up during the whole fprocess and thus prevent precipitation 0 the salt cake, and keep the pressure up during the Whole operation, to prevent the liberation of steam in the circu lating system. We explode the gases into the furnace by the heat internally contained roduceparticles so fine that they lose their moistui e, first, by the heat contained therein, second, by convection, and, third, by radiation, so that the particles take fire only a short distance from the not Zles, themselves furnishing heat which was formerl obtained from the illuminants furni'shed y the foreign fuel. The fine partlcles of valuable mineral content, which float away in the gases leaving the furnace, are recovered in the Cottrell precipitator,

till

and utilized. Preferably a balanced draft .L"

is maintained in the furnace.

While we have in the subsequent cianns defined the invention In the tern-1. a process and apparatus for the treatment of waste liquor resultin. from the digestion of weed in the production of cellulose, it will be understood that the invention is not necessarily limited to the treatment of such liquor but is capable of practice in the treatment of liquid-containing material in which it is desired to evaporate theliquid content and consume the combustible content, opuite irre spective of the recovery of any inorganic content, for it will be readily seen that have provided, by the present invention, for

cure an effluent rich in sodium sulfid, and,

while this is one of the valuable results of the invention according to the exemplification thereof herein illustrated and described,

we desire, by no means, to limit the invention thereto. Other liquidand combustiblecontaining substances than those hereininentioned may be employed as the starting materials, as will be apparent to persons skilled in the art, and many different kinds of such substances may be subjected to the treatment herein described even though the purpose be merely to consume'them for the generation of heat or power, or for obviat: ing the necessity of discharging them into rivers or streams, o r otherwise disposing ofsaid invention, and described; a way. of making, using andpractising the-same, although without attempting to-set-forth .all of the forms in which it maybe made, all of'the modes of its use, or allof. the ways in which it can be practiced, what we claim is 1 1. The herein described process of treat-1 ing waste liquor which comprises exploding 1. waste liquor 1n a furnace and subjecting the-- disintegratedparticles toheat to cause the evaporation of the liquid content,-'and the combustion of the combustible content thereof.

2. The herein described process of treating waste liquor which consists in subjecting waste liquor to heat while maintainingit under a pressure greater than its vapor pressureat that temperature to generate an; explosive force therein, liberating the liquor and thereby causing its. disintegration into fine particles, evaporating the'liquid content of such particles, and burning the combustible content of such particles.

3. The herein described process of treating waste liquor which consists in subject- 'mg waste liquor to high heat and pressure to generate an explosive force therein, and then liberating the liquor in the presence of radiant heat to cause the disintegration of the liquor and the evaporation of the liquid content of the resultant particles, and burning the combustible content of such particles.

4.. The herein described process of recovering waste products which consists in subjecting waste liquor to heat and pressure to generate an explosive force therein and liberating the liquor, thereby causing its disintegration or disruption 1nto fine particles, evaporating the liquid content of such particles, burning the combustible content of such particles, and recovering the non-combustible inorganic content of $110.11 particle disintegrated. particles of esa-era 5. The herein described process of treating waste liquor which comprises subjecting waste liquor to high temperature and pressure, circulating such liquor at high velocity, and liberating a portion thereof in the fire chamber of a furnace-to cause the disruption of such liquor into fine particles, the evaporation of the liquid content and the com bustion of the combustible content of the particles so liberated. v

.6. The herein described process of treat ing Waste liquor which comprises subjecting waste liquor to high temperature while maintaining it at a pressure greater than. its

vaporpressure- .at that. temperature, circulat-- 7ov I ing such liquor at high velocity, then liberat ing a portion of such circulatingliquorin a fire chamber-t0- cause the disintegration or a disruption thereof into fine particles by the explosive :force thus generated, and subjecting such particles to a high degree of radiant waste liquor at high velocity through a heater-and by an explosive force generated therein disintegrating or disrupting such liquorinto fine particles, and subjectin the liquor to ra iant and convectedxheat. I

8. The "herein'described process of recovering waste products which consists in partially evaporating and concentrating black greater thanits vapor pressure atthat tem therein and then liberating such black liquor in a furnace in finely disrupted 'particles, evaporating the liquid content and .perature to generate. an explosive force H burning the combustible content thereof, and 2 recovering the soda content.

9. The herein described process in thetreatmentiof black liquor which consists'in -heating black liquor-to a vaporizing temperature while held under a pressure greater than its vapor pressure atsuch temperature to generate an explosive force therein and liberating such liquor in'a spray of finely disrupted particles, evaporating the liquid content and burning the combustible controstatic precipitation. P

10. The herein'described process oftreating black-liquor which consists in partially evaporating and concentrating blackliquor, disrupting the same in a furnace by an explosive force generated in such liquor, and evaporating the liquidcontent thereof by the combustion of the combustible content git; iike liquor without the'use of a foreign e 1 1 The herein described process of treating black liquor which comprises mixing .tent ofsuch particles and recoverin finely divided particles of mineral content 1 elec- I finely divided salt cake and black liquor, circulating such mixture at high velocity and at great pressure, heating said mixture to a high temperature to generate an explosive force therein, liberatin a portion of said mixture in the fire cham er of a furnace and exposing the particles thereof to radiant and convected heat generated by the combustion of previous y liberated liquor in such chamber.

12. A etc in the process of treating waste liquor whicv consists in atomizing and disrupting the same by an internal disruptive force generated therein.

13. A step in the process of treating waste liquor which consists in atomizing the same by an internal disruptive force generated therein by relieving the pressure on the liquor after heatin the liquor to a high temperature while un er a pressure greater than the vapor pressure at that temperature.

14. The herein described process of treating black liquor which consists in disrupting black liquor in a heated atmosphere by an internally generated explosive force into fine particles, evaporating the liquid content thereof and charring the combustible content thereof by radiant heat generated by the combustion of like previously disrupted evaporated and charred particles.

15. The combination with a furnace and means for evaporatin and concentrating black liquor, of means %O1 heating such concentrated liquor to a high temperature, means for subjecting such heated liquor to great pressure to generate an explosive force therein without the generation of steam, and

' means for delivering such liquor in a stream or spray to said furnace, whereby when liberated 111 said furnace it explodes into fine particles.

16. The combination with a furnace, of a circulating system for waste liquor including one or more pumps for subjecting such liquor to great pressure and a heater for heating the liquor to a high temperature without the generation of steam when under such pressure, and a nozzle for liberating a stream of said liquor in the fire chamber of such furnace.

17. The combination with a furnace, of

means for generating an explosive force-in blfiaclt liquor and exploding said liquor into finely disintegrated particles in the fire chamber of such furnace Without the use of an air or steam jet, and burning the combustible content of such particles.

18. The combination with a furnace, and

means for separating and recovering from the gaseous products of combustion soda particles escaping from such furnace, of means for evaporating and concentrating blacl: liquor, means for confining and gen-- erating an explosive or disruptive force in such concentrated black liquor, means for continuously liberating such blackv liquor into the fire chamber of such furnace in internally disrupted particles, whereby the heat generated by the combustible content of such particles evaporates the liquid con tent of the next succeeding particles, .and means for recovering the smel-ted soda con.- tent of such particles.

19. The combination With a furnace, of a heater, a circulating system including pumps for circulating black liquor at a high velocityumd great pressure through said heater and generating an explosive force in said liquor, means for mixing and delivering a mixture of black liquor and salt cake to said circulating system, and a nozzle connected to said circulating system for delivering said mixture so heated to the fire. chamber of said furnace.

20. The combination With a furnace, of a circulating system for black liquor comprising conduits, pumps for subjecting said liquor to and forcing it at great pressure and high velocity through said conduits, and a heater for heating it to a high temperature to generate an explosive force therein, and a nozzle leading from said system into said furnace.

21. The combination with a furnace and a nozzle for delivering a stream of black liquor into the fire chamber thereof, of a circulating system for such liquor with which, saidnozzle is connected, said system comprising conduits, a coil, and one or more umps for circulating and maintaining the iquor in the conduits and coil under high pressure, and means for heating said coil and liquor passing therethrough to a high temperature while the liquor is at a high pressure, whereby a disruptive or explosive force is generated therein.

22.-The herein described process of recovering waste products which comprises generating an explosive force in and exploding black liquor within a furnace, subjecting the disintegrated particles to heat to cause the evaporation of the liquid content and the combustion of the combustible con; tent thereof, and separating the soda from the waste products of combustion by electro static precipitation.

2-3. The herein described process of recovering waste products which consists in subjecting black liquor to heat and pressure to generate a disruptive or explosive force therein, then liberating the liquor to permit .24. The herein described process of recovering waste products which comprises generating an explosive force in and explo'ding the finer particles of the soda, content ing black liquor in the furnace, subjecting from the products of combustion. the disintegrated particles to heat to cause In testimony whereof We have afiixed our 10 the evaporation of the liquid content and signatur s.

5 the combustion of the combustible content.

thereof, smelting a portion of the soda con- HUGH K. MOORE. tent and recovering the same, and recover- JQHN T. QUINN.

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