Abstract: A method for feeding a slurry of chips and liquid to a prehydrolysis reactor in the production of dissolving pulp. The slurry is pumped by using at least one pump to the reactor, and alkali is fed into the at least one pump 5 for adjusting the pH of the slurry to a range of 7-10.

Abstract: A process for producing dissolving pulp from comminuted wood-based fibrous material. The process includes the following consecutive stages: cooking comminuted fibrous material with alkaline cooking liquor in a kraft cooking process to produce pulp; treating the cooked pulp in caustic extraction at a temperature of 70-110° C. and in an effective alkali concentration of 60-120 g/l for at least 5 minutes, and washing and oxygen delignifying the caustic extracted pulp.

Abstract: A method and system for heating a hydraulic digester, such as a single-vessel hydraulic digester, which has a top separator, a level of chips and a liquid phase above the level of chips. The method includes: a. entraining chips in liquor to produce a slurry having a first temperature, b. feeding the slurry of chips to the digester through the top separator, c. supplying direct steam to the liquid phase between the level of chips and the top separator to heat the slurry to a second temperature for the impregnation stage, wherein the steam is fed by using at least one steam injector having a plurality of steam discharge openings; and d. heating the slurry to a third temperature and cooking the chips in a cooking zone, and withdrawing the cooked pulp from the bottom of the digester.

Abstract: A method and system for heating a hydraulic digester, such as a single-vessel hydraulic digester, which has a top separator, a level of chips and a liquid phase above the level of chips. The method includes: a. entraining chips in liquor to produce a slurry having a first temperature, b. feeding the slurry of chips to the digester through the top separator, c. supplying direct steam to the liquid phase between the level of chips and the top separator to heat the slurry to a second temperature for the impregnation stage, wherein the steam is fed by using at least one steam injector having a plurality of steam discharge openings; and d. heating the slurry to a third temperature and cooking the chips in a cooking zone, and withdrawing the cooked pulp from the bottom of the digester.

Abstract: A method of and an apparatus for processing cellulose pulp of wood processing industry. The method and assembly may be used, on one hand, as a pressure diffuser for washing the pulp before an oxygen stage and, on the other hand, the separation of soap, gas and/or other light materials from filtrates and from black liquor of a cellulose mill in a pressurized device, as well as the new process connections enabled by the method. The method and apparatus may process filtrates from brown stock washing and bleaching as well as black liquors from a digesting department and an evaporation plant. By way of example, the filtrate of the washing department is pumped to the digesting department of a sulfate cellulose mill as well as the black liquor taken from the digesting department to an evaporation plant.

Abstract: A method of and an apparatus for processing cellulose pulp of wood processing industry. The method and assembly may be used, on one hand, as a pressure diffuser for washing the pulp before an oxygen stage and, on the other hand, the separation of soap, gas and/or other light materials from filtrates and from black liquor of a cellulose mill in a pressurized device, as well as the new process connections enabled by the method. The method and apparatus may process filtrates from brown stock washing and bleaching as well as black liquors from a digesting department and an evaporation plant. By way of example, the filtrate of the washing department is pumped to the digesting department of a sulfate cellulose mill as well as the black liquor taken from the digesting department to an evaporation plant.

Abstract: A method of and an apparatus for processing cellulose pulp of wood processing industry. The method and assembly may be used, on one hand, as a pressure diffuser for washing the pulp before an oxygen stage and, on the other hand, the separation of soap, gas and/or other light materials from filtrates and from black liquor of a cellulose mill in a pressurized device, as well as the new process connections enabled by the method. The method and apparatus may process filtrates from brown stock washing and bleaching as well as black liquors from a digesting department and an evaporation plant. By way of example, the filtrate of the washing department is pumped to the digesting department of a sulfate cellulose mill as well as the black liquor taken from the digesting department to an evaporation plant.

Abstract: A chemical pulp mill system and method of using black liquor flashing steam from a digester system comprises generating black liquor in the digester system, sending the black liquor to an evaporator system without using any pre-evaporator system, flashing the black liquor in the evaporator system to yield steam, and using at least some of the steam for chip steaming in a chip bin and/or for supplying in-direct heat exchangers in the digester system for pre-heating white liquor and/or filtrates for use in the digester system.

Abstract: A chemical pulp mill system and method of using black liquor flashing steam from a digester system comprises generating black liquor in the digester system, sending the black liquor to an evaporator system without using any pre-evaporator system, flashing the black liquor in the evaporator system to yield steam, and using at least some of the steam for chip steaming in a chip bin and/or for supplying in-direct heat exchangers in the digester system for pre-heating white liquor and/or filtrates for use in the digester system.

Abstract: Yield, particularly when treating hardwood chips, can be improved by at least 1-2% in a kraft cellulose pulping process by keeping the temperature and effective alkali (EA) low during impregnation, and by keeping the EA low in at least a first cook stage. After cooking, the pulp is subjected to cooling low EA liquor, e.g. to reduce its temperature to below 120° C. (preferably below 100° C.) with an EA below about 5 g/L (expressed as NaOH). Continuous treatment in a continuous digester system is preferred, with the EA below about 20 g/L during impregnation and the first cook.

Abstract: A method of cooking pulp in an alkaline batch process (using one or more batch digesters) improves pulp bleachability. The wood material is supplied to the digester; the cellulosic material is pre-treated in the digester with a first liquor, the first liquor is displaced by a second liquor, the displaced first liquor is led to a further treatment, the cellulose material is treated with the second liquor, and the cooked pulp is removed from the digester. The second liquor is displaced as two consecutive parts, i.e. as strong black liquor and weak black liquor, and after cooling in a heat exchanger the strong black liquor thus obtained is fed into the digester as the first liquor in a subsequent batch (in the same, or a different, batch digester).