Method and device for oxygen delignification for bagasse pulping

Abstract

The invention discloses a method and a device for oxygen delignification for bagasse pulping. According to the method, the oxygen delignification procedure is added between the cooking and bleaching of the conventional bagasse pulping process, cooked bagasse pulp is treated by the washing procedure at a washing section, the pulp enters a vertical pipe of a medium-consistency pump through a pulp outlet screw of a pulp washer, a certain amount of NaOH is added on the vertical pipe, then the pulp is conveyed by the medium-consistency pump, enters a steam feeding device where steam and oxygen are added, is mixed uniformly in a mixer and enters an oxygen delignification tower for delignification reaction, and finally the pulp after reaction is filtered and washed to enter a subsequent bleaching section. Based on the method and the technological conditions, residual lignin in the cooked bagasse pulp can be effectively removed, the consumption of chemicals at the bleaching section is reduced, the pollution load of waste water is greatly reduced, and meanwhile, the bagasse pulp has high yield and quality.

Description

technical field

[0001] The invention belongs to the field of papermaking beating technology, and in particular relates to an oxygen delignification method applied to bagasse pulping and equipment required for realizing the method. Background technique

[0002] Fiber raw materials are the material basis of the pulp and paper industry, and wood is the main and excellent fiber raw material. However, the lack of forest resources in our country, coupled with the country's requirements for environmental protection and sustainable development, has resulted in a shortage of high-quality wood fiber raw materials that can be used in the pulp and paper industry. The development of non-wood fiber raw materials for pulping and papermaking is an effective way to solve the shortage of raw materials in my country and develop a circular economy.

[0003] Bagasse is a by-product of the sucrose manufacturing process. At present, the commonly used bagasse pulping method in China is alkaline or...

Examples

Embodiment 1

[0028] Example 1 The present invention is applied to the bagasse pulping process using elemental chlorine-free bleaching (ECF)

[0029] like figure 1 As shown, the inventor combined the technical solution of the present invention to carry out technical transformation to an existing bagasse pulp pulping process. The existing bagasse pulp pulping process is as follows: bagasse pulp is cooked by kraft method, and the cooked bagasse pulp goes through the washing section and directly enters the bleaching section, and the bleaching section uses chlorine dioxide bleaching→alkaline extraction strengthened by oxygen and hydrogen peroxide → Chlorine dioxide bleaching (D0-Eop-D1) three-stage bleaching.

[0030] The technical improvement plan is: add the oxygen delignification section (O) between the washing section and the existing bleaching section, that is, after the cooked bagasse pulp passes through the washing section, the pulp (with a weight concentration of 10-12%) Enter the m...

Embodiment 2

[0043] Example 2 The present invention is applied to the bagasse pulp pulping process of two-stage elemental chlorine-free bleaching (ECF)

[0044] This example is a greenfield project with an oxygen delignification stage added before the first stage bleaching.

[0045] Due to the use of two-stage bleaching, in order to reduce the pressure of subsequent bleaching and improve the selectivity of delignification, the bagasse pulp can enter the subsequent bleaching stage with a lower kappa value and higher brightness. Add hydrogen peroxide to the prime segment. Therefore, the bleaching procedure of this example is Op-D-Eop (ie, hydrogen peroxide-enhanced oxygen delignification→chlorine dioxide bleaching→oxygen and hydrogen peroxide-enhanced alkaline extraction).

[0046] The specific process conditions are as follows: the weight concentration of bagasse pulp entering the oxygen delignification section is 12%; the NaOH addition point is adjusted to the pulping screw of the pulp ...

technical field

[0001] The invention belongs to the field of papermaking beating technology, and in particular relates to an oxygen delignification method applied to bagasse pulping and equipment required for realizing the method. Background technique

[0002] Fiber raw materials are the material basis of the pulp and paper industry, and wood is the main and excellent fiber raw material. However, the lack of forest resources in our country, coupled with the country's requirements for environmental protection and sustainable development, has resulted in a shortage of high-quality wood fiber raw materials that can be used in the pulp and paper industry. The development of non-wood fiber raw materials for pulping and papermaking is an effective way to solve the shortage of raw materials in my country and develop a circular economy.

[0003] Bagasse is a by-product of the sucrose manufacturing process. At present, the commonly used bagasse pulping method in China is alkaline or...

Examples

Embodiment 1

[0028] Example 1 The present invention is applied to the bagasse pulping process using elemental chlorine-free bleaching (ECF)

[0029] like figure 1 As shown, the inventor combined the technical solution of the present invention to carry out technical transformation to an existing bagasse pulp pulping process. The existing bagasse pulp pulping process is as follows: bagasse pulp is cooked by kraft method, and the cooked bagasse pulp goes through the washing section and directly enters the bleaching section, and the bleaching section uses chlorine dioxide bleaching→alkaline extraction strengthened by oxygen and hydrogen peroxide → Chlorine dioxide bleaching (D0-Eop-D1) three-stage bleaching.

[0030] The technical improvement plan is: add the oxygen delignification section (O) between the washing section and the existing bleaching section, that is, after the cooked bagasse pulp passes through the washing section, the pulp (with a weight concentration of 10-12%) Enter the m...

Embodiment 2

[0043] Example 2 The present invention is applied to the bagasse pulp pulping process of two-stage elemental chlorine-free bleaching (ECF)

[0044] This example is a greenfield project with an oxygen delignification stage added before the first stage bleaching.

[0045] Due to the use of two-stage bleaching, in order to reduce the pressure of subsequent bleaching and improve the selectivity of delignification, the bagasse pulp can enter the subsequent bleaching stage with a lower kappa value and higher brightness. Add hydrogen peroxide to the prime segment. Therefore, the bleaching procedure of this example is Op-D-Eop (ie, hydrogen peroxide-enhanced oxygen delignification→chlorine dioxide bleaching→oxygen and hydrogen peroxide-enhanced alkaline extraction).

[0046] The specific process conditions are as follows: the weight concentration of bagasse pulp entering the oxygen delignification section is 12%; the NaOH addition point is adjusted to the pulping screw of the pulp ...

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