TH35239A - Continuous boiling with cold saturation and DOM control. - Google Patents

Abstract

DC60 (23/09/47) The wood chip treatment method allows chemical pulp (eg brown pulp) to be produced with enhanced fiber strength properties in zone or first. The wood chips are cooled (eg approx. 60-120 ° C) with first alkali liquid (25-35 g / l, which can be expressed as NaOH), then in the upper part of the apparatus. In continuous sub-zone or second stage, wood chips are then treated with first alkali liquid. Which has an alkali concentration which is at least 5 g / l less than that of the first liquid (eg 10-20 g / l) and Between approximately 120-160 ° C (ie 130-150 ° C). As such, extraction takes place to influence the changes in the treatment zone after the second zone has passed. The wood chips are then boiled at temperatures around 140-180 ° C (eg 150-170 ° C) and higher in the second zone. The wood chip treatment method allows chemical pulp (such as brown pulp) to be produced with enhanced zone or first fiber strength properties. The wood chips are cooled (eg approx. 60-120 ° C) with first alkali liquid (25-35 g / l, which can be expressed as NaOH), then in the upper part of the apparatus. In continuous sub-zone or second stage, wood chips are then treated with first alkali liquid. Which has an alkali concentration which is at least 5 g / l less than that of the first liquid (eg 10-20 g / l) and Between approximately 120-160 ° C (ie 130-150 ° C). As such, extraction takes place to influence the changes in the treatment zone after the second zone has passed. The wood chips are then boiled at temperatures around 140-180 ° C (eg 150-170 ° C) and higher in the second zone.

Claims (18)

1. The process of boiling the finely ground cellulose fibrous material consists of the following sequential steps: (a) In the first step, the finely ground cellulose fibrous material sludge is treated with a primary alkali solution at a temperature between approximately 60-120 °C and at a primary alkali concentration greater than 10 g/L, expressed as NaOH. (b) In the second step, the finely ground cellulose fibrous material sludge is treated with a secondary alkali solution at a secondary alkali concentration equal to or less than 5 g/L, expressed as NaOH, and at a temperature between approximately 120-160 °C. (c) The finely ground cellulose fibrous material sludge from step (b) is boiled at a temperature between approximately 140-180 °C to produce pulp. 2. The procedure as specified in Claim 1, where step (a) is performed at a temperature between 95–105 °C, step (b) at a temperature between 130–150 °C, and step (c) at a temperature between approximately 150–170 °C, and the temperature in step (c) is at least 5 °C higher than the temperature in step (b). 3. The procedure as specified in Claim 1, whereby step (b) is performed using white liquid and step (a) is performed using white, green or black liquid. 4. The method as specified in claim 1, in which procedure (c) is performed at an alkali concentration of approximately 18-40 g/L throughout. 5. The procedure as specified in Claim 1, which includes an additional step for material washing after step (c) and in which step (b) is performed in a countercurrent manner. 6. The procedure described in Claim 1 shall be performed in which step (a) shall be performed to obtain a first concentration of approximately 25-35 g/L in the form of NaOH, and step (b) shall be performed to obtain a second concentration of approximately 10-20 g/L in the form of NaOH, and in which the second concentration shall be approximately 7-15 g/L in the form of NaOH, which is less than the first concentration. 7. The method described in claim 6 consists of an additional step (d) placed between steps (a) and (b) which is a step for the partial extraction of the first alkali-containing liquid from the material. 8. The procedure as specified in claim 7, in which steps (d), (b) and (c) are performed in an upright continuous digester. 9. The method specified in claim 8, in which procedure (a) is performed in a continuous, upright submachinery but only partially. 10. The procedure as specified in claim 8, whereby step (b) is performed by removing the liquid from the digester, heating the removed liquid, and recirculating the removed liquid back into the digester, adding filtered liquid or water to the previously heated and recirculated liquid in sufficient quantity to approximately compensate for the liquid extracted in step (d), and adding white liquid to the recirculated liquid in sufficient quantity to ensure that the desired alkali concentration of that fraction is achieved. 11. Treatment method of sludge made of finely ground cellulose fibrous material using a continuous upright digester feeding system. The digester has first and second sieve assemblies placed near the top of the digester, with the second sieve assembly below and spaced apart from the first sieve assembly. The procedure consists of the following continuous and sequential steps: (a) Partially feeding the finely ground cellulose fibrous material through cold saturation with an alkali liquid, with an alkali concentration of at least 10 g/L (expressed as NaOH) at a temperature between approximately 60-120 °C, and feeding the cold saturated material to the top of the digester; (b) Partial extraction of the alkali liquid from the material using the first sieve assembly; (c) Treatment of the material with the second liquid. (d) Boiling the material under the second sieve assembly at a temperature of 120-160 °C; and (d) Boiling the material under the second sieve assembly at a temperature of approximately 140-180 °C. 12. The method as specified in claim 11, where step (b) is performed to extract the liquid at a temperature of approximately 80-120 °C and with an alkali concentration of approximately 3-5 g/L. 13. The procedure specified in Claim 11, where step (a) is performed at a temperature between 80–110°C, step (c) at a temperature between 130–150°C, and step (d) at a temperature between 150–170°C, and the temperature in step (d) is at least 5°C higher than the temperature in step (c). 14. The procedure as described in claim 11 includes an additional step (e) which involves the removal of some fluid from the mud using a third sieve assembly placed above the first sieve assembly and the recirculation of the fluid recovered in step (e) back into the feed system. 15. The procedure specified in Claim 14 shall be performed in which step (a) shall be performed to obtain a concentration of the first alkali between approximately 20–35 g/L, expressed in terms of NaOH, and step (c) shall be performed to obtain a concentration of the second alkali between approximately 10–20 g/L, expressed in terms of NaOH. 16. The procedure described in Claim 11, whereby step (c) is partially performed, is sub-procedure of (1) liquid removal from the sludge using a second sieve assembly, (2) recirculation of the majority of the removed liquid back into the digester to approximately the level of the second sieve assembly at least, (3) addition of boiling liquid and liquid compensation to the recirculated liquid to produce the added liquid, and (4) heating of the added liquid, whereby steps (1) - (4) are performed so that the recirculated liquid to the digester is at a temperature of approximately 140–160 g/L, expressed as an alkali concentration of approximately 10–20 g/L, expressed as NaOH. 17. The method described in Reputation 16, in which procedure (a) is performed using a wood chip storage bin connected to a wood chip conveyor pipe which is connected to a screw-driven pump and which is connected to a high-pressure feeder as a feed system. 18. The procedure as specified in claim 16, in which step (3) is performed by adding filtered liquid or liquid water for compensation and white liquid for boiling.