US1813826A - Apparatus for the distillation of solid carbonaceous substances - Google Patents

Description

3. Sheets-Sheet l Inventor f/fnfage..

by Af- 5 Sw-44 l fttorney July 7, 1931. E. R. suTcLlFFE APPARATUS FOR THE DISTILLATION OF SOLID GARBONACEOUS SUBSTANCES Filed Sep't. 23. 1926 l E. Rl suTcLlFFE 1,813,826 APPARATUS FOR 'IHE DISTI'LLATLON OF SOLI) CARBONACEOUS`-SUBSTANCES Filed sepi. 23. 192s 3 sheets-sneer z Jly 7,1931. Y

ttorney July 7, 1931. E. R. su'rcLlFFE y 1,313,826

APPARATUS FOR THE DIISTILLTION OF SOLID CARBONACEOUS SUBSTANCES 3 Sheets-Sheet Filed Sept. 25. 1926 Inventor Patented July 7, 1931 EDGAR RUSE SUTCIIFFE, OF LEIGI-I, ENGLAND APPARATUS FOR THE DISTILLATION Oi SOLID CARBONACEOUS SUBSTANCES Application filed September, 1926, Serial fNo. 137,316, and in'Great Britansepteniber 28, 1925.

This invention relates to process and .apparatus for the distillation of coal and-other solid carbonaceous substance, more especiallyrof the lrind in which heaters or regenerators are used as means for heating `the gas, or the gas and steam, or the steamused as the vehicle of heat internally applied for carrying out the distillatioinand rthe in- -vention is more especially applicable tothe 1 distillation of solidcarbonaceous substances of the character of coal, -shale or Wood by the internal application of heat.

The invention is especially applicable for carrying out v'distillation under the conditions hereinafter set forth.

The invention has for an especial object to utilize lsteam in the distillation of carbonaceous substances such as coals and shales, or as the vehicle of heat. applied in the distillation, and to utilize a relatively considerable quantity of steam under economical conditions, so as -to secure an eX- ceptionally high yield of by-products and especially of ammonium sulphate and tar, together with a substantial quantity of light oils, and avery high yieldof gas.

According -to the "invention the 4heat of the gases and yvapours from the retort =is utilized for the production of steam for use in the distillation, or as the vehicle of heat applied in the distillation.

According to the invention moreover the gases `and vapours comprising `.the surplus steam used in the distillation or as vthe vehicle ofheat, are brought into intimatev'contact With hot Water, Which is thereby heated to boiling point, and steam is Athereupon evaporated vfrom the heated Water for passage into the retort after lfirst being heated 40 as `for example Within-a blast stove or regenerator. Y

The invention comprises a y'method lnvolving the alternate use of retorts provided for operationv in `pairs or other number With corresponding heaters, blast stoves, .or re- -constructional features applicable to appa ratus of the type indicated.

The inventionv comprises the features of method and apparatus hereinafter described.

The utilization of the heat ofthe gases and vapours from the retort for the pro` duction of steam for use in the distillation may advantageously be carried out in apparatus such as hereinafter described, or it may be carried out in apparatus such as described in the specification of the prior Patent No. 1,584,487, or it may be carried out under conditions in Which the heat is applied externally to the retort in which the distillation is effected, or in Whichheat is partly applied externally -and partly internally, or partly or entirely by the use of heated gases passed through the retort, or partly ormain ly or entirely in the use of steam preheated before admission to the retort.

The invention may advantageously be carried out under moderate temperature conditions, that is to say, in which the maximum temperature applied to the charge vto be distilled is about 750O C. Thus, Where the steam is used as a vehicle for the heat applied in the distillation,'the steam will be pre-heated to a temperature correspondinglyhigher than that indicated. lt will however be understood that the maximumtemperature in distillation is substantially under 1000O C., rinforder thatthe use of steam shall result in the decomposition of methane, and that its reaction with carbon for the production oftvater gas may be avoided or. minimized. rlfhus, under these conditions a relatively high yield of hydrogen results,

,with a correspondingly lower proportion of carbon mon-oxide, than if the temperature were sufficiently high to iavour the water gas reaction.

It it be assumed that lOO lbs. of steam be admitted to the retort for every 100 lbs. of coal to be distilled, and if the water vapour and gases in the retort oH-take be assumed to have for example a temperature of OOO to 3500 F. there is theoretically more than sutcient heat available to vaporize 100 lbs. of water at the saine temperature. Thus, it the gas and vapour from the retort oit-take are sprayed with the water for example at 1800 F. the water used may be heated for example to 2l()o F. and thus on the evaporation ot a part of the water and consequent cooling of the remainder to about 190 F., a substantial proportion suoli as lbs. of steam may be produced which may be compressed to the working pressure in the retort, and inay be passed through the retort after iirst being preheated as for example, in a blast stove or regenerator. Thus steam is rendered available by the utilization of the heat ot the gas and vapour produced in the distillation.

It will thusbe understood that the heat of the gas and vapour produced in the distillation may be utilized in a scrubber or generally in a heat exchanger of any suitable forni.

No limitation is involved to the type of scrubber or heat exchanger used nor to its construction or operation, it being` understood that the heat of the gas and vapour from the retort is utilized directly for bringing` to about boiling point a water liquor which is evaporated for the supply of vapour for circulation through the retort. Similarly, no limitation is involved to the type ot' evaporator used nor to its construction, nor to the means of maintaining reduced pressure or partial vacuum therein.

It will be understood that the vapour is advantageously passed through a heater, blast stove or regenerator betere passing into the retort where it is heated to the degree necessary for carrying out the distillation under the conditions described. The retort may be provided with two such heaters, blast stoves or regenerators, which may be used alternately for suitable periods such as one-halt hour. The heaters, blast stoves or regenerators may be heated by the coinbustion therein of gas, and the steam pro-` duced in the manner before described may be passed through the heated blast stoves or regenerators and may be projected therein with other Oas or steam. Or instead one heater, blast stove or regenerator mayV be provided for each retort, the make of gas being discontinued in one retort during the heating period of its blast stove oi regenerator.

The gas and vapour from the retort may be sprayed with tar or other liquor before horizontally Vdisposed pipe j.

laisses being sprayed by the water liquor which is heated for evaporation in the manner described. Similarly, a part only ot the gas and vapour from the retort may be used according to the invention, and means may be provided whereby, when the make otl gas from one retort of a pair is suspended during the heating of its corresponding blast stove or regenerator, the gas and vapour from the other retort of the pair may be passed through the heat exchanger', whereby one heat exchanger and evaporator may thus be used for two or more retorts.

The invention is diagrammatically illustrated in the accompanying drawings in `which Figure l is a diagrammatic view of the apparatus employed for utilizing the heat oi the retort vapours and gases for the production of steain Jfor use in the distillation.

Figure 2 is a diagrammatic view of the retort and connected heaters or regenerators.

Figure 3 is a view in elevation, partly in section, of a superheater, heater and retort.

Figure 4; is a View in elevation of two retorts.

In carrying the invention into effect as illustrated in Figure l, a scrubber a may be provided of the spray type, which may consist of a casing that may, for example, be disposed in position between two retorts such as b, and that may be divided into two parts by a vertical partition c or be otherwise formed into two parallel compartments, the second of which may be shorter than the first and both terminate at the lower end in a contracted open part al dipping into an open tank or tray l by which a liquid seal is maintained. The partition 0 extends short of the bottom so that thus the gases and vapours which enter the casing at its upper end adjacent the upper end of the respective retorts b may pass downwardly in one compartment and upwardly in the next as indicated by the arrows, a spray of water being provided at the upper end of each compartment for cleaning the gases and vapours and separating 'from them the solid particles thatinay remain suspended therein, and this tank or tray d may drain to the ammonia liquor receiving tank of the plant, which may be disposed beneath and at the rear of the retorts and of the regenerators of the plant. From the second compartment of the scrubber a, the gases and vapours may issue into part of the gas main c which is disposed or has its lower part disposed at a slight inclination from the horizontal towards the liquid outlet pipe e1, and in which gas main e the gases and vapours may be further sprayed through a A special pump may be provided for the circulation of the water or liquor to the scrubber a.

The liquor in the tank or tray d is kept of.. mi..

separate from the liquor used for spraying the gases and vapours in the gas main. c. The greater part of the hot water or liquor is circulated by another pump g and passed through the pipe extending at the upper part of the greater part of the length of the gas main c which, for the purpose, may be enlarged in diameter, and spray pipes f1 may extend within the main and thus through these spray pipes f1 a large vlume of het water or liquor is conveyed and sprayed through the gases and vapours as they pass through the main. The hot water or liquor thus sprayedl returns through the llowerniost art of the Gas main c into. the

liquid outlet pipe e-land passes into a settling tank 71., and thus a constant circulation of hot water or liquor is maintained through the gas main, and as this main carries a large volume of steam, the steam is condensed and raises the temperature of the hot water or liquor approximately to boiling point for example 210 F. as it enters the settling tank it. The settling tank 7i is 1 provided in its upper part with an inverted cylinder /il substantially less in diameter thanv the tank 7L, and open at its lower end so that thus, as. the hot water or liquor enters the tank it, it flows over the closed top of the inverted cylinder lil and thence passes downwardly, the tar settling at the bottom of the tank 7i, while the hot water or liquor passes upwardly within and through the inverted cylinder k1, and thence passes into the casing of an. evaporator or flash tank e' disposed adjacent the upper end of the settling tank 7i, where the hot water or liquor may flow over a weir 'il or weirs, and thence into an outlet pipe 2 and! downward to a pump tank y' which, in turn, feeds the circulating pump g. Over the evaporator casing or flash tank z' a cylindrical steam receiver or anti-priming vessel is provided having at its lower end a spiral or other admission passage by which any particles of water that may entraiiied, may be deposited and drain back tothe casing z', the object being effectively to drain the steam as it enteis the receiver 7c.

A high pressure steam ejector Z may be mounted upon. the steam receiver 70 and is actuated by live steam, the ejector l maintaining suction onA the steam reccivertl andy consequently onthe evaporator casing or "l flash box e', whereby steam iashes olf the hot water or-liquor in passing through the evaporator casing. The vapour thus drawn off is passed. down a pipek Z1 into the main connecting pipe leading to the retorts o. At the position of connection an exhaust steam ejector may be provided which may. be supplied with steam from a steam engine, and which isk exhausted at a slight pressure above the atmosphere andl may form .an ejection apparatus to assist in. maintaining suction in the pipes leading from the steam receiver 7c and evaporator 2'.. The steam thus drawn olf thence passes through one or other of the valves leading into one or other ofthe retorts of the plant according to the cycle of operation. Overflow pipes may be provided from the settling tank 7L into an oven flow tank, so that if' too much liquor comes over, it may flow back automatically for recirculation through the system, while overflow pipes may also be provided from the pump tank j by which surplus. water or liquor may pass to the settling tanks of the sulphate plant.

ln operation the temperature of the hot water orA liquor as it passes into the pumps may be about 190 F., whileron entering the gas main, the water or liquor may be about 1800 F. and will become heatedk in the gas main to about 210O F., it being understood that steam is produced in the evaporator under 'the low pressure induced by the ejector which may be from 7 to l0 lbs. absolute,`

and the water on reaching the pump tank may cool to about 190o F. and the steam passed to the regenerator wheie it is heated before passage through the retort in which its heat is utilizedy in the distillation of thev charge therein.

lt will be understood that the actual temperatures may vary according to the conditions prevailing, those indicated being given by way of example.

lt willl be understood that drainage pipes may be provided for the tar and liquors.

Thus, according to the invention a considerable quantity of steam may be generated under economical conditions and used in the distillation, whereby exceptionally high yields of by-products and a high yield of gas 'of good caloritlc value are secured. Thus, the gas and hydrocarbon vapours leaving the retorts will carry a considerable quantity of water vapour. The temperature on leaving the ietoits may be for example 350 F. In passing through the gas main the water vapour is condensed, as is also the 4greater part of the content of tai', and the gas and vapours leave the gas main at a' cooled for example to about 185 F. It has been found that the use of steam as a circulating medium under the conditions indi cated give exceptionally good results where the amount of steam used is el lbs. per lb. of coal distilled, but no limitation is involved to the amount of steam used, and the amount of steam used may be varied according to the yields required in particular cases, but in general the amount of steam used may be substantially less.

lt is preferred to use a steam injector as a convenient means of creating the necessary vacuum in the evaporator and of applyingpressure Within the retort.

The following figures demonstrate the Specific heat of gas and hydrocarbon vapours a Specific heat of Watervapour at temperatures shown at f d Temperature of liquor after circulation 210 Fahr. Temperature of liquor for cireulation 188 Fahr. Latent heat of water vapour at 212 Fahr 970 B. t. u. Latent heat of water vapour leavinT flash b at 183 Fahr DSS B. t. u.

Specic heat of water 1 Temperature of gases L vapo 350 Fahr. Temperature of gases and vapours leaving apparatus 185 Fahr.

The latent heat oi' the hydrocarbon vapours is not taken into account.

The conditions based on each 100 lbs. oi coal under carbonization may be taken to be as follows Weiglit of gases and hydrocarbon vapours-:40 lbs.

Condensable hydrocarbon vapours in apparatuszl() lbs.

Steam passed to retort per 100 lbs, of c0al=100 lbs.

Steam recovered by apparatus=120 lbs.

Steam added as exhaust steam and for ejeetors=60 lbs.

The steam decomposed in tbc retort, say=5 ibs.

Steam and vapor condensed and passed from apparatus as surplus liquor=25 lbs.

Vapours contained and mixed with gases leaving apparatus at X in proportion at temperature named about l vapour-1 gas=30 lbs.

On the basis of the above indicated data the following figures show respectively the steam quantity and heat equations and the utilization of heat absorbed in the process STEAM QUANTITY EQUATION o eratine' the HEAT EQUATION Quant/tics of heat absorbed 'in the process Freni sensible heat of gases and hydrocarbon vapours entering at 350 and leaving at 1S5=40 .3 (350-l85)=1980 B. t. u.

From sensible heat of water vapour condensed in apparatus=(l80- -30) .5 x (S50-212) =l0,05 B. t. u.

From sensible heat of water vapour entering at 350 and leaving apparatus at 185 Fahr. =30 x .5 x (S50-185).

:2475 B. t. l1. From latent heat of steam condensed by apparatus= (lS0-5-30) x 970 =l40,650 B. t. u. Total=l55,ll0 B. t. u. absorbed.

DISTRIBUTION OF HEAT ABSORBED'IN THE PROCESS In 120 lbs. vapour exhausted from flash box and vaporized and passed to retort=l20 x 988 :118,560 B. t. u. Radiation losses 36,550 B. t. u,

Tomi =i55,iio B. t. u-

For passing to the retort the recovered vapour at 8 lbs. absolute requires heating to 213O Fahr. corresponding to an absolute pressure of l5 lbs. per square inch, and it is demonstrable that the energy in the G0 lbs. ejector steam and exhaust steam will eil'ect the required duty.

Thus, with ample margin for radiation losses the use of 60 lbs. of steam can induce a circulation effect equal tov 180 lbs. or steam.

Means may be provided for the periodic admission of milk'of lime into the tray tank and at the lower end of the scrubber or heat exchanger and of the evaporator, refuse tanks may be connected for the reception of the sludge and spent lime and liquor under the control of valves, and the sludge and spent lime and liquor may be periodically discharged from the 'refuse tanks through valves.

It will be understood that gas and vapour admitted to the heat exchanger may be at a temperature of about 300o F. to 3500 F., and that as the liquor admitted at the top of the heat exchanger will have a temperature of about 200D F., the liquor on arriving at the lower end will have acquired a temperature of about 212o F., and possibly higher depending upon lthe pressure and other conditions under which the apparatus is operated. A certain part of the hot liquor will be evaporated in the evaporator as the boiling point will be reduced according to the vacuum usedl The vapour produced is then passed into dthe retort together with the other gases that may be used and with the steam that is projected into the retort lfor the purpose of circulation, while the liquor accuinulating inthe evaporator and which has fallen somewhat in temperature due to its partial evaporation is recirculated into the heat eX- changer as before described. In this way a considerable part or" the heat of the gas and vapour from the retort ofi-take may be recovered and used for the generation of vapour for return into the retort.

in carrying the invention into effect in the arrangement of the connected retorts and heaters or regenerators as illustrated in Figures 2, 3 and Ll, two vertical retoits a., a (Figure 2) may be provided, together with two corresponding` vertical heaters or regeneratois A, and the retorts and heaters are Vso connected that the charge in cach of the retorts in alternating periods is adapted to be internally heated by means of gas, or of gas and steam, or of steam, which is heated to the necessary temperature by being passed through the corresponding heater. n a plant comprising the elements indicated in Figure 2, one of the heaters or regeiierators is heated in alternating periods and during the respective heating periods the corresponding retort is cut out. Thus, if the heating period and the gas-making period are each one-half hour, one retort is subjected to heat for one-half hour and is cut out from the direct application of heat for another half-hour.

Valves B may be provided in the oiftake of the respective retorts, and these may be respectively closed when the respective retort fio is to` be isolated from, the directl application of heat. F or this purpose a butterfly .type of valve sadvantageously employed, and it s mountednpon a, spindleadjac'ent theupper part of the offtake. outlet and in such manner that. the lower edge of the valve by partial rotation of the valve` isk moved; outwardly and; upwardly in. Opening. Such valves are adapted. for isolating the respective retorts ad a in such manner as, while allowing the outward passage of any produced in the retort cut out, under. theetlect ot heat previously applied, will avoid; drawing through the retort any products of; combustion derived from the corresponding and connected heater or regenerator, during the period the retort is thus isolated. :t will thus be understood that during the periods in,A which the` respective retorts. arey isolated the heat already applied to the charges therein` may be, gradually transmitted from the outside inwardly of the briquettes or piecesA or particles ofcoal undergoing distillation, andV that although the direct application: of heat to the charge, is discontinued during those. respective periods, the vaporization continues under the conditions prevailing. Thus the respective valves B are so provided; and set that the outlet of gas and vapour from. the isolated retort may be permitted while avoiding the. induction of the products of combustion from the corresponding and; connecting heater or regen` erator.

When two retorts a (L are employed. foralternate operation inthe manner described, and, are disposedl in adjacent positions as illustrated: in Figure 2, the offtake pipe for thel gas and vapour, as illustrated in Figure et, may be common tothe two retorts and the upper part may be conveniently formed as a hopper-shaped fitting. having inclined lower wallaandat each. side4 an outlet valve of the form. described may be mounted, while at the upper. end of the hopper-shapedpart a Spayillg UOZZle ornozzles maybe provided by which the vapour may be sprayed with water, tar or other liquid as it passes into the hopper-shaped part and downwardly through the otftake pipe.

rlhe lheaters or regenerators may advantageously be workedunder pressure such as about from 5, to l() inches of water, whereby under the method of regulation described none of thejproductsjof distillation from the isolated retort may pass into the corresponding` and connected heater or regenerator.

In practice, washed and stripped gas from the retorts may be used for the purpose of being heated and circulated for the application of heat to the charge in the retorts. Or instead, crude gas may be used, or as an alternative that is preferred, steam may be used as the medium for the application of heat.

the inlet offgas for combustion,therein is cutl olf, while the .heating medium is then adinitieel. b y suitable valves.

According t0 a modification, two heaters or regenerators may be employed for each retort, and both the heaters or regenerate-rs heated in the saine periods, and the heating medium passed through them in the same periods., whereby the retort is isolated or. cut off from the, application of heat during the heating periods ofthe heaters orA regenen ators.

The retorts ai, a as illustrated in Figures 2 and 3 may be provided of a cylindrical form of large capacity and,I vertically disposed advantageously one beside theother, and supportedy upon a frame so that the lower ends of the retorts are disposedf at a sufficient height above the ground for, discharging` shoots to be provided, the lower ends of which are conveniently disposed; whereby the carbonized residguefmay bev discharged into a conveyoror in towagons. The retort chainbersorcavities may be cylindrical, but near the lower end thereof a number of ports C are provided at equal distances apart in the same circular line to. communicate with an annular flue D surrounding the retort at about the same level as the ports; and conimunication is made between this annular iue andthe upper paflt of the corresponding and. adjacent heater or, regenerator A by a short horizontal flue, through which the whole of the heating medium may pass for use in distillation, in the retort, the heating medium passing into Athe annular flue and being uniformly distributed into the retort through theJ ports aforesaid. l A

At the top of thc retort (L any suitable means may be provided for charging, and such means may. be similar to those employed in charging blast furnaces and may comprise a skip or bucket and .hoist s uch as commonly7 employed in such fur,l naces. A bucket E may be provided having a movable base and4 cover, whereby on the bucket being lmounted in position and upon the mouth of the retort a, andy thel cover lowered upon the bucket, the baseffalls for the discharge of its contents into the retort.

Beneath the ports C providedin the retort as aforesaid, it will be understood'thatua space or chamber F out oftlhlfe course of the heating gases is provided in which the residue which has been degasied to the extent required: may accumulate; and beneath the lower end of the retort a discharging shoot may be provided of the type in which the outlet endis out of alignment with the upper end adjoining the retort outlet, and in which means are provided for, feeding out the resiusually l due continuously or periodically. Having regard to the large capacity of the retort two such discharging shoots G (Figure 3) may be provided symmetrical and oppositely disposed with their outlet ends also oppositely' disposed, and capable of discharging into the saine wagon. For this purpose each of the charging shoots may be diverted downwardly and outwardly into a vertically disposed part, and on the outwardly curved lower wall of the outwardly diverted part of the shoot a series ot star wheels H may be mounted one beside the other, on a horizontally disposed spindle, so that upon rotation of the spindle the discharging coke is fed out into the vertically disposed part of the shoot. The lower end of the vertically disposed part of each shoot is diverted inwardly and is provided with a downwardly and inwardly inclined bottom wall upon which the discharging coke falls and from which it is projected through a lateral opening in position opposite to that of the other shoot, and such lateral discharge opening may be provided with a hinging cover-plate.

The spindle on which the star wheels H ot the colte discharging mechanism are mounted may be operated by means such as an externally mounted ratchet wheel and a pawl adapted to impart to the ratchet wheel a movement that may be variable in extent, whereby the rate of discharge may be varied. A swinging balance weight which may for example consist of a bar or plate hanging across the shoot and in position above the star wheels, or a number of such, mounted in position in line, may be provided for the control of the coke passing over the star wheels. It will be understood that instead of star wheels provided as hereinbetore described any equivalent adapted continuously or periodically to feed out the coke may be employed.

The lower portion of the retort below the heating zone is arranged so that steam may be blown as a cooling medium for the residue, which steam becoming heated conveys the heat up into the retort, in such way that the heat from the cooling residue contributes considerably to the heat required for carbonization.

.In lieu of steam, water may be sprayed in for the same purpose.

The heaters or regenerators A may be provided as cylindrical containers or chequered refractory brickworl, and at the upper end of each a combustion chamber may be provided surmounted by a curved dome in which a series of burner nozzles I may be provided through which, in the heating periods, a mixture of gas and air may be passed by which the heater or regenerator may become heated to the degree required for imparting its heat to the heating fluid in the succeeding period, for circulation through the charge in the adjacent retort.

At the upper end of each heater or regenerator A an oil burner or burners may be provided for the purpose of applying heat at starting; but in normal running, gas generated in the plant may be used.

Exhaust steam Jfrom an engine may be utilized as the heating medium in the plant, and this may be supplemented by the heat recovered from the gas and vapour leaving the retort, as hereinbefore described.

As an alternate means for the production of steam for circulation through a blast stove regenerator or heater, water may be sprayed into a second blast stove regenerator or heater heated by the waste products from the first heater, in such way as to produce steamv for passing through the heater either as the sole means for heat conveyance or as supplementary to other sources of gas or steam.

A superheater J or superheaters may be provided in the outlet flue or in the outlet flues of the heaters or regenerators, through which superheater Orsuperheaters the hot waste gases may pass in the respective alternate periods, and the steam superheated therein may be used for direct admission to the respective retorts through the annular Hue D or otherwise.

It will be understood that the respective vparts of the plant are insulated to avoid radiation losses.

I claim:

Apparatus for the distillation of a solid carbonizable substance comprising in combination a retort, a scrubber, a gas main, the said gas main being adapted for use as a scrubber, an evaporator separate from the said scrubber, a superheater, and means for their connection in series, the said means being adapted for the admission into the retort of superheated steam from the superheater, for the admission into the scrubber of a mixture of gas, vapour and steam from the retort for admission into the main of gas from the scrubber, for the admission into the evaporator of hot water from the main, and for the re-circulation ot part of the hot water back from the evaporator to the main, and for the admission into the superheater of the steam from the evaporator, substanially as hereinbefore described.

EDGAR ROUSE SUTCLIFFE.

Images