Jan. 7, 1947. J. c. F. c. RICHTER ' 2,414,062 APPARATUS FOR HEATING‘ AND CONTROLLING THE TEMPERATURE IN A CONTINUOUSLY OPERATING DIGESTER Filed July 30‘, 1945 Jnren/or: 6.9 M2 H for»? y Patented Jan. 7, '1947 2,414,062 UNITED STATES PATENT OFFICE 2,414,062 APPARATUS FOR HEATING AND CONTROL LING THE TEMPERATURE IN A’ CONTINU OUSLY OPERATING DIGESTER Johan Christoffer Fredrik Carl Richter, Oslo, Norway, assignor to Aktiebolaget Kamyr, Karl- l stad, Sweden, a company of Sweden Application July 30, 1945, Serial No. 607,696 In Norway May 2, 1944 4 Claims. _ (Cl. 92-7) 2 l The present invention relates to an apparatus duits may be connected to the pump and to the heat exchanger. for heating- and for controlling the temperature of the contents of a continuously operating di By allowing liquor to circulate alternately gester for digestion of ?brous material, of the type through the several circulation conduits at suit able intervals of ‘time, and by supplying to the which is provided at one end with a device for feeding raw material into the digester, and at its other end with a device for discharging the digested product, and through which digester the contents thereof, that is to say, the material liquor or removing from the same the necessary uor, thus move continuously from the feeding end to the ‘discharge end. The contents of the di gester may, but need not necessarily,vbe main tained at a pressure which exceeds the VELDOI‘i'? zation pressure of the digestion liquor at the 15 circumference, thus causing it to ?ow in various amount of heat, the desired temperature control, that is, heating or cooling, may easily be effected in the digester,‘ and by alternately introducing charged into the digester, and the digestion liq~ 10 the circulating liquor from various points of the maximum temperature prevailing in the digester. directions through the digester transversely there of, an as uniform heating or cooling as possible is obtained over the entire cross section of the digester. The supply of the required amount of heat to the circulating liquor may be e?ected either directly, as for instance by introducing It is the purpose of the present invention to provide an apparatus which renders it possible fresh steam into the liquor. or indirectly through the heat exchanger, and by means of the latter easily to attain and maintain the desired tem perature or temperatures at desired points or in 20 it is also possible to remove heat from the circu lating liquor and thus from the digester. predetermined zones between the feeding end and The accompanying drawing illustrates by way the discharge end of the digester, in such man of example and schematically an apparatus ac~ ner that at such points or zones the tempera cording to the present invention. Fig. 1 is a, sche ture becomes as uniform as possible over the 25 matic showing of the apparatus with a portion entire cross section of the digester. of the digester in axial section, and Fig. 2 shows According to the present invention there are schematically the apparatus with the digester in connected to the digester, at a point between the feeding end and the discharge end thereof, or at several such points, two or more ‘circulation conduits located outside the digester, in such manner that the outlet or outlets from the di gester of each circulation conduit, which outlet cross section. The circulating liquor is drawn through an out 30 let from the digester covered by a sieve I by a circulation pump 2 which pumps it through a heat exchanger 3 back to the digester through an inlet 4, or several inlets, arranged diametrically or outlets are suitably covered by a sieve pro opposite the sieve I. The latter has suitably a vided in the wall of the digester, and the inlet or inlets into the digester of each circulation 35 peripheral extension of 120", since in such‘ case the circulation liquor is distributed in the best conduit are positioned substantially diametrical possible manner over the entire cross section of ly opposite to one another. The outlets and in ' the digester, as indicated by the arrows in Fig. 2. lets of all circulation conduits are located in one The digester is further provided with a similar and the same transverse plane through the di sieve 5 and an outlet diametrically opposite to the gester, or substantially in such a plane, and the sieve l, and with an inlet 6 diametrically oppo several circulation conduits are displaced, as far site the inlet 4. ‘By a simple reversal of the di as their outlets and inlets are concerned, rela rection of flow by means of the slide 1 of a re tively to one another around the circumference versing valve, such reversal being indicated by of the digester, preferably at an angular distance the dotted lines in the drawing, the required corresponding to 360° divided by the number of equalization of the temperature over the cross circulation conduits, that is to say, in such man~ section of the digester may be easily effected. ner that the outlets as well as the inlets are distributed at preferably equal angular distances from one another around the circumference of' the digester. The circulation conduits are con nected with a pump and with a heat exchanger or the like located outside the digester, by means of a reversing valve of such construction that by means of said valve any of the circulation con _ In the position of the slide 1 of the valve that is illustrated with full drawn lines in Figs. 1 and 2, the pump 2 draws the circulating liquor from the digester through the sieve I and forces it through the heat exchanger 3 to the inlet or inlets 4. If the slide 1 is moved to the position shown with dotted lines, then the pump 2 draws the circu lating liquor through the sieve 5 and forces it 2,414,062 through the heat exchanger 3 to the inlet or inlets 6. It is of course possible to use three sieves, each having a peripheral extension of 120°, and a corresponding number of inlets, but the arrangement above described using two sieves l and 5 has been found e?icient for practical pur \ 4 1. In an apparatus ‘for heating and control ling the temperature in a continuously operat ing digester for digesting ?brous material, the combination of means for charging raw material U into the digester at one end thereof, means for dischargingv digested product from the digester at the other end thereof, at least two circulation conduits located outside the digester and con~ In addition to supplying heat by the aid of a nected to the digester at a point intermediate heat exchanger, as'above described, it is also 10 the feeding end and the discharge'iend there possible by means of a heat exchanger in a simi of, each circulation conduit having its outlet from lar circulation system at another stage of the the digester and its inlet into the digester posi digestion, for instance at a further point on the tioned substantially diametrically opposite to one path of travel of the mass through the digester, another, the outlets and inlets of all circulation to remove heat in order to lower the temperature conduits being located substantially in one and poses. within a certain limited zone. the same\,transverse plane through the digester, ‘ In addition to effecting control of the tempera ture by supplying or removing heat, the appara tus according to the invention may, of course, 'be utilized for introducing into the digester, simultaneously or separately, the chemicals that the outlets and the inlets of the several circula tion conduits being respectively spaced relatively to one another around the circumference of said 20 digester, a pump, a heat exchanger, and a revers~ ing valve connecting said pump and said heat exchanger to said circulation conduits in such are required for the digestion, such as acid, al kali, S02, and so forth. It is also possible by ‘means of the arrangement to remove, for in tance, S02 from the digester, ‘by lowering the‘ pressure of the circulating liquor outside the digester in order to partially free the liquor from $02, after which the liquor is returned to the manner that said conduits may be selectively con ' nected to said pump and said heat exchanger by means of said reversing valve. _ 2. An apparatus as defined in claim 1, wherein the outlet from the digester of each circulation conduit has a peripheral extension of 120° along thecircumferenc f the digester. It will be understoodthat the several circula 3. An apparatus‘ as de?ned in claim 1, wherein 30 tion conduits should preferably lie as nearly as the outlet from the digester of each circulation possible in one and the same plane asgfar as their conduit is covered by a sieve in the wall of the inlets into and outlets. from the digester are 'digester. I ~ concerned. Usually,_,however, digesters used for 4. An apparatus as de?ned in claim kit/herein continuous digestion‘have a considerable length, 25 the outlets from the digester and the inlets into such as twenty meters or more, between the feed the digester of the several circulation conduits ing end and the discharge end, and in view here- ' are respectively spaced at equal angular distances of it‘ is, of course, of less importance if the in from one another around the circumference of circulationjvsystem. ' - lets and outlets of the several circulation con duits lie at a distance of, say, one meter from one another in the longitudinal direction of the digester. I claim: the digester. JOHAN CHRISTOFFER FREDRIK , - CARL RICHTER.