USRE18200E - of stockholm - Google Patents

Description

mus Sept. 22, 1931 I UNITED STATES PATENT orrlcs GUSTAF HAGLUND, OI STOCKHOLM, SWEDEN, ASSIGNOR '10' PATENTAKTIEBOLAGET GBbNDAL-BAMEN, OF STOCKHOLI, SWEDEN,,A LIMITEDQOMPANY CELLULOSE COOKING Io Drawing. Original No. 1,791,476, dated February 3, 1981, Serial No. 432,564, filed March 1, 1880,1111! in Sweden April 10, 1929. Application for reissue filed June 8, 1931. Serial No. 542,688.

In the cooking of cellulose it has been suggested to add waste liquor from a prior coo ing operation to the fresh cooking liquor to be used, for ,the purpose of obtaining a re,-

;, sultant waste liquor containing a high con centration of organic matter. Likewise, in

stead of utilizing waste liquor from a prior cooking operation, the waste liquor from a cooking apparatus in operation may be em P e a ere resort is had to the use of waste liquor in such a manner however, undesirable effects occur in the cooking as compared with the ordinary use of a water solution of the cooking medium, without the addition of waste liquor. When waste liquor is employed as noted, the cooking process proceeds more .slowly, and the product readil tends to assume a dark color and also to ome weak- :0 ened as a result of the extension of the cookin period. I

he present invention has for its object to overcome these disadvantages whether the fresh cooking liquor is mixed with cooking liquor from previous cookings or with liquor from a cooking operation in action. According to my invention, prior to the cooking operation the raw material, for example wood chips, is first caused to absorb the fresh cooking liquor prepared in the usual manner with water, and thereafter waste liquor is added, obtained either from a prior. cooking operation, or from a cooking apparatus the contents of which are in the process of cooking. An illustrative procedure for can ing out the process of my invention is as f0 lows: A fresh cooking liquor, which has not previously been used for cooking and which ma or may not contain gases, 1s fed into a coo g 40 apparatus containing the wooden chips or other raw material. The remaining unabsorbed liquor may then be withdrawn to the extent necessary to accommodate the cooking liquor to be subsequent]; added. Therea after the apparatus is fills with a cooking liquor consistin of a mixture of the same fresh liquor as t at which has been absorbed and a waste liquor from a previous or concurrent pulp cooking operation. The cooking operation in the apparatus thus charged is thereupon be un and proceeded with to the degree desired.

This preliminary soaking will not occasion any loss of time as compared with the usual operation, because under all circumstances the chips require time for the absorption of the cooking liquor. The process requires however, an increased pumping action, and, for effecting a rapid penetration of the unmixed cooking liquor into the chips, the

cooking apparatus 'is preferably completely filled with the fresh liquor in the preliminary step. The pumping means are so arranged that the liquor is introduced into the cooking apparatus under pressure in order to facilitate the saturation of the chips and thereby shorten the time for the absorption.

This saturation of the chips with the fresh cooking liquor prior to the cooking operation, ma of course, be conducted outside of the cob 'ng vessel or apparatus which is to be used, and the saturated chips thereafter transferred to said apparatus, the apparatus filled with fresh cooking liquor mixed with waste liquor from the sources noted, and the cooking operation proceeded with.

The impregnation of the chips with the fresh cooking liquor before the cookin process proper, as noted, is desirable in eacfi cooking of cellulose and should be brought about as substantially and rapidly as possible, for which purpose the use of pressure in the preliminary soaking is highly desirable in cooking operations conducted as at present. This. preliminary soaking of the chips with fresh cooking liquor before the cooking operation and the subsequent cookin with a mixed cooking liquor as described, 1s of like advantage in other processes of cellulose cooking, for instance in alkaline cooking operations, although the beneficial efl'ect is less marked than'in the production of eulphitecellulose. v 7

Having now particularly described the I nature my invention and the manner of its operation, what I claim is:

1. In the cooking of cellulose, for example sulphite cellulose, the improved process of producing waste liquor containi a high percentage of organic matter which comprises, impre atlng the raw material, for

' example woo chips, with a cooking liquor produced in the usual manner without the addition thereto of waste'liquor, and then 1 conducting the cooking operation In the presence of waste liquor. i

2. A process as defined in claim 1 characterized m that the preliminary impregnation of the raw material with the usual cooking liquor is carried out under pressure for the purpose of facilitatin the impregnation.

. 3. In the cooking 0 cellulose, for example sulphite-cellulose, the improved process of producing waste liquor containing a high percentage of organic matter whlch comprises, soaking the raw material, for eizample wood chips, in a cooking liquor reduced in the usual manner without the ad ition thereto of waste liquor, removing part of the cooking liquor in which the raw material has been soaked, and then conducting the cooking operation with the usual cooking liquor mixed 7 with waste liquor froma previous cooking or from a cooking ap aratus in operation. 86 .4. A process as de ed in claim 3 characterized 1n that the preliminary-soaking of the raw material with the usual coo liquor is carried out under pressure for the purpose of facilitating thesoaking. 40 In testimony whereof I aflix my si ature. GUSTAF HAGL NDg