US1804116A - Digesting system - Google Patents

Description

May 5, 193i. A. F. RICHTER DIGESTING SYSTEM Filed Deo. 12, 1929 2 Sheets-Sheet l May 5, @3L A. F. RICHTER DIGESTING SYSTEM med Dec. 12, 1929 j @2/m2, l W 1f@ 2:6/

2 Sheets-Sheet 2 Patented Mayd 5, 1931 recrue A siren vsm'rlss PATENT-OFFICE i AUGUST F. RICHTER, F WATERTOWN, NEW YGBK, ASSIGNOR T0 S'EBBINS EINE-BIMB- ING & MANUFACTURING COMPANY, A CORPORATION 0F NEW YORK DrensfrIN'G SYSTEM Application led December 12,-1929. Serial No. 418,558.

This 'invention relates to an improved method andapparatus for the cooking or digestion of fibrous material such aswood chips.A

a In such a cooking operation, chips or the like are usually placed in aA digester which is subsequently filled with sulphite or other chemical liquor, and after the digester has been closed, steam is turned into the digester t@ for a number of hours to create within the digester, sufficient heat and pressure to eect xthe digestion. While the cooking is proceed-ing, gases and vapors are relieved from the digester, and in the early days of the in- 115 dustry,'these gases and vapors, were wasted. Subsequently, and up to the present time, various efforts have been made to recover the heat units and the sulphur dioxide from the escaping gases and vapors.

The primary object of my invention is to improve the process and to better utilize the escaping vapors and gases so as not only to recover the heat units and save the gases, but to employ the same to bring a digester which has just been filled, up to the temperature and pressure which must be maintained during the cooking operation. In my system, the contents of three or more digesters may be cooked in rotation, and the low pressure gases and vapors which are escaping from one of the digesters during the end period of the cook, are employed to force fresh sulphite liquor or pre-conditioned sulphite liquor through a pipe line leading to a second di gester which has previously been filled with chips or the like, and is about to begin the 'cooking' operation. Meanwhile, vhigh pressure gases and vapors from a third digester, in accordancewith my invention, are also introduced into the liquor line to add their heat units and gas to the liquor flowing. to the second digester. In my system, I employ an injector'of the exhaust steam type, so that the low pressure gases and vapors from the first digester are assisted in their escape from that digester, and so that the mixture of liquor, gases and vapors may be fed through the pipe line to the second digester under sufficient pressure to overcome the pressure which builds up in the second digester to the time the pressure in the latter reaches that employed during the'main portion of the cookf ing operation'. 4 j

It is well known that in pulp plants having a battery of digesters, that either high pressure or low pressure steam and gases are constantly escaping from at least some of the digesters, and in accordance with my system, these gases and vapors are employed, not alone to pre-condition and pre-heat liquor flowing to a digester or digesters, which has or have just been lled with chips, but the type of injector which I employ, enables me to build up the pressure and temperature in the filled digester or'digesters to the point where steam must be turned into the same to effect the main portion of the cooking operation. For example,'assuming a battery of three digesters, low pressure steam and gases, during the end portion of a'cook,may escape from one digester for, say one hour, and this may beled to the injector for use in forcing the sulphite liquor to a second digester which has just been filled with chips or the like, and which requiresabout two hours time to be brought up to the cooking temperature and pressure. Durin that two hours, the low pressure gases an steam can be led through the injector to the second digester for a pe. riod of one hour, or for that hour, high pressure gases and steam may also be led through the injector from a third digester which is undergoing cooking and the passage of gases and vapors from the third digester to the injector may be continued for another hour, or until the second digester has been brought up to the temperature and pressure required for the cooking operation. l

With the foregoing objects outlined and with other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter de- -scribed in detail, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

Referring to the drawings,

' Fig. 1 is a diagrammatic view of a digester system in accordance with my invention.

Fig. 2 is a vertical sectional viewv of an 100 injector of the type which may be employed with my system.

Fig. 3 is a horizontal sectional view of a portion of this injector.

In the drawings, I have illust-rated the invention in connection with three digesters, 4, 5 and 6, but I desire it to be understood that the invention may be used with three or more digesters.

Each digester is provided at its top with a valved low pressure gas and steam relief branch 7 which discharges into a manifold pipe 8 that communicates with a down pipe 9.

The top of'each digester is also provided with a valved high pressure relief branch 10,

l and these branches lead into a manifold 11 which communicates with a down pipe 12.

The bottom of each digester is connected by a valved branch 13 to a manifold 14, through which pre-heated and pre-conditioned liquor, as well as some steam, may be fed into any of the digesters from the injector 15. The latter may be of any suitable construction, but it is preferably of the type shown in Figs. 2 and 3, and is provided with an outlet check valve 15a. The low pressure gas and steam enter one end 16 of this injector, and this entrance is controlled by a hand operated valve 17. After passing into the chamber 18 of the injector, the low pressure gas and steam enters an-exhaust steam and gas nozzle 19 before it passes into a draft tube 2O which forms part of the injector.

It is well known that when steam or gases are condensed, a vacuum is created, the degree of which is dependent upon the liquid of condensation. In an injector of the type which I employ, a very high degree of vacuum is obtained by the condensation of the exhaust steam and SO2 by the sulphite liquor which enters the injector from a pipe 21 which discharges into the injector through an inlet 22 that communicates with the space between the nozzle 19 and tube 20. The highest vacuum-is at the point of the nozzle 19 where the steam, gases and liquor meet. The degree of vacuum so obtained is sufiicient to cause the low pressure gases and steam to flow into the injector at an exceedingly highv velocity. They there meet the sulphite liquor, and being condensed by it, give up their momentum to the combined jet, which then flows along the combining nozzle 23 where complete condensation takes place. The jet leaves the end of the combining nozzle at a velocity which is sufficiently high to carry it forward through the delivery nozzle 24, and into any one of the digesters, by way of pipe 14. It will thus be seen that t-he working of the injector is not dependent on steam or gases being supplied under pressure,

an essential determining factor being the steam and gas velocity.

From Figs. 2 and 3, the construction of the double jet injector may be understood.

livery, overflow and liquor pipes. The nozzles include the parts 19, 20, 23 and 24, while in the chamber 18 is fixed a supplementary nozzle 26 which projects into the nozzle 19 and is adapted to be supplied byhigh pressure steam and gases through a valved branch v 27, which connects with the pipe 12. The low pressure gases and vapors entering the injector at 16, pass into the main central nozzle 19 at the mouth of which it meets the sulphite liquor. Condensation immediately takes place, a very high,degree of vacuum being formed, and the combined jet flows forward at .a high velocity through the draft tube 20, into the combining nozzle 23. The region of high vacuum extends to the entrance of the combining nozzle, and at this point, high pressure gases and vapors are admitted through the valvedbranched pipe 28, from the pipe 12, which, iiow'mg in at a very high velocity, impinges on it and are condensed by the combined jet, imparting to the jet a further supply of energy, thus greatly increasing its velocity. After passing through the combining nozzle, the Ajet enters the delivery nozzle 24, where its velocity is reduced, the kinetic energy being changed into pressure energy, and leaving the injector. The liquor thus pre-heated and pre-conditioned, passes through the pipe 14, into a digester which hasl just been filled with chips or other fibrous material, and which is at the commencement of the cooking period.

By introducing high pressure gases and vapors into the injector first through the branch pipe 27, the injector may be set in action, and then, low pressure gases and vapors may be introduced into the end 16 of the injector, and the liquor may be admitted through the inlet 22. This will enable the injector to start automatically if the jet is in any way broken.

In the operation of the plant, high pressure gases and vapors may not at all times be present for the purpose of starting the injector, so in the chamber 18 I place an annular chammer 27a which has a mouth, opening around the auxiliary nozzle 26. This annular chamber may be supplied either with pressure steam or as from any suitable source, .and introduced through the valved pipe line 276. Obviously, when such steam or gas is admitted, it will flow from the chamber 27a, into the nozzle 19, and will act to set up the circulaing the exhaust gases and vapors -from other digesters, and at the same time, the heat of these gases and vapors will be imparted to the liquor passin to a digester, and said liquor will absorb S 2 gases which were discharged from other digesters.

The sulphite liquor may be ed tothe injector from a storage ltank 30 by way of a rlhe liquor can be passed from this tank through a valved pipe 33 to the pipe 21, and furthermore, in casethereis a period where pre-heated and pre-conditioned liquor from the injector is not flowing through the pipe 14 to one of the injectors, it may be passed by a valved conduit 34, into the accumulator tank. Furthermore, an arrangement of this character permits me to pass either high pressure or low pressure gases or vapors from the pipes 9 and 12, through the injector, directly into the accumulator tank, so that such gases and vapors may be employed to pre-heat and pre-condition the liquor in that tank before it is fed from the latter through the pipes 33 and 21, and into the injector, for passing the same into any one of the digesters which has A just been filled with chips or other fibrous material.l

.It is usual in digesterplants, to shut down on Saturday night, and to leave some of the digesters sealed, that is, sealed to prevent the escape of gases or va ors.` At the same time, the steam is cut o from such digesters.

Furthermore, if an accumulator tank is used, l

this may also/be sealed on Saturday night.

vNOW, on-Monday morning, when it is desired to resume operations, the gases which may be relieved rom the sealed digesters, do not contain suflicient heat units for use in heating up liquor which is to be introduced into a digester that has'just been illed with fresh chips or other ibrous material. While the liquor content at such time in the' accumulator tank is heated to some extent, it is not feasible to mix such liquor in the injector with the low temperature gases coming off of the previously sealed digesters, due to the fact that the relatively hot liquor will not condense the gases coming over from the digesters, and thus create the vacuum which is Y necessary for the practical operation of the injector. To eliminate this disadvantage, when the digesters are tobe unsealed on Monday morning, I lintroduce steam into these digesters in the usual Way to build up the temperature and pressure, and as Ithe high pressure gases and vapors escape into the pipe 12, they are mixed in the injector with :liquor from the storage tank 30. However,

such mixture will not have suicient temperature at that time to be used in a digester which has just been lled with fresh chips or the like, so I by-pass the mixture through a valved conduit 35, which leads from the pipe 14 to the storage tank 30. Due' to this arrangement, the liquor from 4the Storage tank can be recycled through the injector for a time suiiicient to properly pre-heat' the liquor by means of the high pressure gases vand vapors, until the mixture is in condition to be fed through the pipeline 1 4 to a digester which has just been filled with fresh chips or thev like. At such time, the valve 36, inthe bypass line is closed, so that the hot liquor will flow through the line 14, and pass the check valve 15a. When thepressure has been built up to the Adesired degree in a digester during the starting of the cooking therein, the check v'alve 15a will cut 0E the feed of the hot liquor to that digester, and then steam may be turned into the latter, and the hot liquor from the line 14 can be diverted into another one of the digesters which 'has just been filled with-chips or the like.

ltwillbe noted that. the injector is arl ranged at the bottom portions of the digesters, and that the storage tank 30 and accumulator tank 32 are elevated relatively to the injector, so that the liquor may also ow by gravity from the tanks 30 and 32, to the injector..

In plants of this character, the pressure of gases and vapors escaping .through the high pressure branch 10 of one digester, may vary from that which is escaping through the high pressure branch 10 of one or more of the other digesters, so in order to prevent any detrimental fluctuations of pressure in the line 12 which feeds the branches 27 and 28, I interpose in said line, an equalizer Vor expansion chamber 37.

As an example, let us assume that the contents of the digester 4 has been cooked, and that low pressure gases and vapors are being relieved from that digester, While digester 6 has ust been iilled with chips or the like, and digester 5 is on the main portion of the cooking operation, that is, the portion in which the temperature and pressure are at the maximum. Now, the lovv pressure gases and vapors from the digester 4, can flow by Way of 'pipes 7 and 9, into the end 16 of the injector,

and in passingthrough the latter, they will induce the iiow of liquor through the pipe 21, and upon contact with this liquor, the gases and vapors will be condensed, and the vacuum thus created, will act to induce additional flow of gases and vapors through the pipes 7 and 9. llhese conditions will create a jet within the injector, which will have suiiicient velocity to enter thedigester 6, and which will continue to enter that digester even after a relatively high pressure has been built up therein. During such time, high pressure gases and vapors may also flow from the digester 5, through pipes 10 and 12, and branch 28, to the injector, and their force will be added to the jet, and at the same time, these gases and vapors will be condensed, and they will augment the jet flowing through the pipe 14 and branch 13 to the digester 6. It will be manifest to those skilled in the art, that by th1s arrangement, I am not only able to save all ofthe heat units and SO2, but save considerable on the steam supply, for I simply utilize the heat units coming over from certain digesters, to heat the liquor in another digester. Furthermore, by utilizing an injector of the type illustrated, I' can eliminate pumps, and this simplifies and makes the apparatus less expensive. v

I desire it to be clearly understood that Fig. 1 of the drawing is more or less schematic, and that it does not show the relative size of the parts, as it is obvious that in actual practice, the digesters, storage tank and accumulator, will each be much larger than the injector.

While I have disclosed the invention in such manner that it may be readily understood by those skilled in the art,I am awarethat changes may be made in the details disclosed, with o ut departing from the spirit of the invention, as expressed in the claims.

What I claim and desire to secure by Let- I ters Patent is:

1. In the digestion of fibrous material, utilizing gases and vapors flowing from a digester to induce the flow of chemical liquor` and to force such liquor into another digester against super-atmospheric pressure existing in the latter digester.

2. In the digestion of brous material, passing gases and vapors from a digester into an injector, contacting said vgases and vapors in the injector with chemical liquor, and thereby creating a vacuum due to the condensation of said gases and vapors, utilizing such vacuum to draw gases and vapors from a digester into the injector with increased velocity, and thereby creating a jet composed of said chemical liquor and the condensates resulting from said condensation, and utilizing this 'jet to force the liquid mixture into another digester against super-atmospheric pressure existing therein.

3.' In the digestion of brous material, passing gases and vapors from a digester chamber into an injector, contacting said gases and vapors in the injector with chemical liquor and thereby condensing the gases and vapors, and

4thus creating a vacuum, utilizing such vacuum to draw gases and vapors from a digester into the injector with increased velocity, and thereby organizing the liquor in the injector into a jet, and utilizing this jet to cause the liquor and condensates to flow into a digester under super-atmospheric pressure existing in the latter.

4. In the digestion of fibrous material, passing a mixture of low pressure gases and vapors from a digester during the end portion of the cook, introducing this mixture into an injector and contacting the same therein with a fiowing stream of chemical liquor, and thereby condensing said mixture and creating a vacuum, utilizing this vacuum to draw some of the mixture into the injector with increased velocity, passing a second mixture of high pressure gases and vapors into the injector and mixing the same with the stream resulting from the contact of the liquor with the low pressure gas and vapor mixture, organizing the combined mixtures and liquor into a jet, and utilizing the pressure of this jet to force the combined mixture into another digester containing fibrous material.

5. In the digestion of fibrous material, passing low pressure gases and vapors from a digester during the last portion of the cooking operation, passing high pressure gases and vapors from another digester during an intermediate portion of the cooking operation, and utilizing these gases and Vapors to induce a ilow of chemical liquor and to prce said liquor into another digester at tor to induce the flow of a stream of chemical liquor and to organize said stream into a jet, and utilizing the force ofthe jet to discharge liquor from this jet into a third digester during the starting of the cooking operation in the latter.

7. In the digestion of fibrous material, passing gases and vapors from a digester during the end port-ion of the cooking period, introducing these gases and vapors into an injector, causing said gases and vapors in the injector to induce the tlow of a stream of chemical liquor into the injector, permitting said liquor in the injector to condense said gases and vapors, and utilizing forces generated in the injector toforce the resulting liquid mixture into the bottom portion of a digester during the starting of the cooking operation in the latter.

8. In the ldigestion of fibrous material, simultaneously passing low' pressure gases and vapors from 'one digester, and high pressure gases land vapors from another digester into an injector, contacting these gases and vapors in the injector with a flowing stream of chemical liquor, discharging the resulting liquid mixture from, the injector into a third digester during the starting of the cooking operation therein.

9. In the digestion of fibrous materi al,

passing gases and vapors from the upper pori icaiie the resulting liquid mixture into the bottom portion of another digester.

10. In the digestion of fibrous material, passing gases and vapors from the upper portion of a digester into an injector, contacting.

these-gases and vapors in the injector With a iiowing stream of pre-conditioned chemical liquor, and utilizing :forces generated in the injector to force the resulting liquid mixture int-o the bottom portion of another digester.

11. In the digestion of brous material, passing gases and vapors from the upper portion of a digester into an injector, ,contacting these gases and vapors in the injector with a dowing stream of pre-conditioned and preheated cliemical liquor, and utilizing forces generated in the injector to force the resulting liquid mixture into the bottom portion of another digester.

12. In the digestion of fibrous material, discharging a mixture of low pressure gases and vapors from a digester during the last portion of the cooking operation, passing a second mixture of high pressure gases and va, pors from another digester during an intermediate portion of the cooking operation in the latter, utilizing these mixtures to create an injector action on a flowing stream of chemical liquor, and thereby creating a high pressure jet of said chemical liquor admixed with the constituents of the gas and vapor mixtures, and utilizing this jet to force the resulting liquid mixture into a digester during the beginning of the cooking operation of the latter.

13. In the digestion oit fibrous material, discharging low pressure gases and vapors and high pressure gases and vapors from a digester during the cooking operation therein, passing all of these vapors into an injector, introducing into said injector for a period of time a flowing stream of chemical liquor, passing the resulting liquid mixture from the injector into another digester, and passing the gases and vapors from the injector during another period of time into an accumulator, and contacting the last mentioned gases and vapors into the accumulator with chemical liquor.

14. In the digestion of fibrous material, leading low pressure gases and vapors from the top of a digester into the nozzle of an injector, mixing chemical liquor with said gases and vapors in a draft tube of the injector, discharging high pressure gases and vapors from adigester and mixing them with the mixture discharged from the draft tube, combining the mixtures in the combining nozzle of an injector, and thereby creating a jet, and discharging this jet through a delivery nozzle o the injector into another digester during the beginning of the cooking operation in the latter.'

15. A digestion apparatus comprising a series of digesters each having at its upper portion, a valved high pressure gas and vapor outlet and a valved low presure gas and vapor outlet, an injector, a pipe line leading from said low pres/sure outlets to the injector, a pipe line leading from said high pressure outlets to said injector, means for introducing chemical liquor into the injector, a. valved inlet provided at' the lower portion of each digester, and a pipe line connecting the outlet of the injector to said inlets.

16. In an apparatus of the character described, an injector casing having an inlet and an outlet, a digester, means for leading low pressure gases and vapors trom the upper portion `ot said digester to the inlet of the injector casing, a first nozzle arranged in said casing and receiving gases and vapors from said digester, a draft tube into which the nozzle projects, a chemical liquor inlet leading into the casing at a point to discharge liquor into the draft tube and around saidl nozzle, a combining nozzle in the casing into which the draft tube projects, a second digester, means for leading high pressure gases and vapors from the second digester into the injector casing so as to discharge the same into said combining nozzle, a delivery nozzle in tlie casing directed toward the outlet of the latter, a third digester, and a valved pipe connecting the outlet end of the injector to the lower portion of the third digester.

17. A digesting apparatus as claimed in claim 16, including an accumulator tank, a valved conduit connecting the last mentioned pipe to said tank, and a pipe connecting said conduit to the chemical liquor inlet of the injector.

18. In adigesting apparatus, a first digester having a valved gas outlet pipe, an injector, said pipe being connected to the inlet of said injector, a second digester, a valved pipe connecting the outlet of the injector to the bottom portion of the second digester,

.a check valve in the last'mentioned pipe,

opening toward the second digester, and means for introducing chemical liquor into an intermediate portion of said injector.

19. In a digesting apparatus, a plurality of digesters, a gas, outlet pipe, valved branches connecting the upper portions of said Vdigesters to said pipe, an injector, said pipe being connected to said injector, an equalizer chamber interposed in said pipe, a second chamber, a valved pipe connecting the outlet of the injector to the second chamber, and means for introducing chemical liquor into an intermediate portion of said injector.

20. In a digesting apparatus, an injector having an inlet and an outlet, a digester, means for leading gases and vapors from the upper portion of said digester to the inlet of the injector, means for introducing a pressure fluid into an intermediate portion of the injector for starting the operation of the latter, means for introducing chemical liquor into an intermediate portion of the injector, a chamber, and means for leading liquor from 5 the outlet of the injector to said chamber.

21. In a digesting apparatus, a lil-st di gester havingV a valved gas and vapor outletpipe, an injector, said pipe being connected to the inlet of said injector, a second digester,

:10 a valved pipe connecting the outlet of the injector to the bottom portion of the second digestcr, a liquor storage tank, a Valved conduit connecting the last mentioned pipe to said storage tank, and a second valved con- 15 duit leading from the storage tank to an intermediateportion of the injector for introducing chemical liquor from the ,storage tank into said injector.

In testimony whereof, l hereto ax my 20 signature.

AUGUST F. RlIICH'lllER.

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