JPS642714B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing mechanical pulp, and more particularly to a method for producing mechanical pulp, which comprises energy-saving refining of compressed deformed chips or compressed deformed wood blocks. In recent years, RMP (Refiner Groundwood Pulp), CRMP
Mechanical pulps such as (chemically pretreated refined groundwood pulp), TMP (thermomechanical pulp) and CTMP (chemically pretreated thermomechanical pulp) are
It occupies an important position as the main raw material pulp for newsprint, medium-quality paper, low-grade printing paper, tissue paper, and sanitary products, and there is a strong demand for its use from the standpoint of resource conservation and pollution prevention. From the perspective of effective use of wood resources or resource conservation in the pulp and paper industry, mechanical pulping methods are
It is superior to chemical pulping methods and will be an extremely important pulping method in the future. However, one of the disadvantages of mechanical pulping when compared to chemical pulping is high power consumption. Electricity consumption in chemical pulping method is 200-400KW/ton, while in mechanical pulping method it is 1500-3000KW.
hour/ton. Therefore, it cannot be said that this is a preferable pulping method from the viewpoint of energy saving.
In particular, the thermomechanical method (TMP method), which has recently attracted attention for its high quality, consumes more electricity than the conventional refiner groundwood pulping method (RMP method). ~
Compared to 1,800 KW hours/ton in the TMP method, it is 2,000 to 2,500 KW hours/ton. Due to the recent rise in energy costs, especially electric power, caused by the recent oil crisis, there is an urgent need to improve energy efficiency in mechanical pulping methods. Various methods have been proposed. They can be broadly classified as follows. (i) Method of refining by adding CMC (carboxymethyl cellulose) and CMS (carboxymethyl starch) to chips - JP-A-1988-
No. 31092 (ii) Method of refining using a refiner element whose groove is filled with plastic -
JP-A-55-30424, JP-A No. 30425 (iii) Refinement using cone disk
JP-A No. 55-128090, (iv) Method for stabilizing refiner load by equalizing chip supply using a ribbon screw - JP-A No. 54-113570 (v) Coarse crushing and compressive shearing treatment of chips (Plex Processing by Screw or Pressmaster) Method of Refining Chips - International Mechanical Pulping
Conference) Preprint (Preprint) 247~
255 (1979), etc., but with the exception of (ii) above, no significant reduction in power consumption while maintaining quality has yet been achieved. The present invention has been made in view of the above-mentioned current situation, and its purpose is to provide mechanical pulp that reduces power consumption during mechanical pulp production and is also excellent in quality. The present inventors investigated the above-mentioned known methods from various angles, and in particular, as a result of intensive detailed investigation of the above-mentioned (v) method for refining coarsely crushed chips and compression-sheared chips, In the multi-stage refining process with two or more stages of processing, by optimizing the energy distribution in each stage, especially by making the power consumption of the first stage smaller than the power consumption of the second and subsequent stages, Even if the power consumption in the production of compressed deformed chips or compressed deformed wood blocks is taken into consideration, the total power consumption can be significantly reduced, and it has been found that the pulp quality is equivalent to or higher than that of the conventional method. That is, in the multi-stage refining process of compressively deformed chips or wood blocks, the present inventors have improved the conventional method by keeping the power consumption of the first stage refining to 5 to 15% of the total refining power consumption. The present invention was completed by confirming that the total power consumption can be reduced by about 20% compared to mechanical pulp of the same quality (same freeness) obtained by multi-stage processing of chips that have not undergone any mechanical deformation. To give an overview of the present invention, the present invention is capable of reducing the power consumption of the first stage of refining by 5% of the total refining power consumption in the production of pulp that can be made into paper by two or more stages of refining of compressed deformed chips or compressed deformed wood blocks. A method for producing mechanical pulp, characterized in that the pulp content is reduced to ~15%. That is, the present invention is characterized in that the power during the first-stage and second-stage refining processing is distributed as shown in the following formula. 1200≦x+y≦2500 (based on Canadian standard freeness CSF 100ml) 0.05≦x/x+y≦0.15 In the formula, x is the power consumption of the first stage refining
KW hours/ton y indicates the sum of the refining power consumption from the second stage onwards, KW hours/ton. The compressed deformed chips or compressed deformed wood blocks used in the present invention can be obtained by processing chips or wood blocks with a screw feeder type press, roller press, hammer mill, etc. and applying mechanical deformation. The power consumption is about 10-30KW hours per ton of wood. The wood used in the present invention may be either softwood or hardwood, and the moisture content of the wood must be maintained above the fiber saturation point (approximately 20%) during mechanical deformation treatment. Needless to say. Room temperature is usually sufficient for mechanically deforming chips or wood blocks, but if the pressing time is to be less than 1 second, the temperature must be raised to around 100°C using steam or the like. Press pressure is 500
~5000Kg/ ^cm2 , and the pressing time is about a fraction of a second to several minutes. The chips or wood blocks may be impregnated with aqueous sulfite or sulfite solution prior to mechanical deformation, and the sulfite water or sulfite may be forced into the refiner during the refining process. In the conventional multi-stage refining process (usually two or three stages), the amount of electricity in the first stage, that is, the energy for defibration, is
Approximately 600 to 1100KW/ton is required. However, in the method of the present invention, the chips or wood blocks are subjected to mechanical deformation, such that during hammer milling of the chips, the chips become broom-shaped;
In addition, during the pressing process of wood blocks, the wood is buckled and the wood is semi-fibered, so the power consumption in the first stage is 60 ~
375KW hours/ton is sufficient [this figure is 5-15% of the total refining power consumption (1200-2500KW hours/ton)], yet it defibrates wood to the same level as conventional methods. be able to. Therefore, from the second stage onwards, it is possible to carry out refining under exactly the same conditions as in the conventional method, and it is possible to obtain pulp of the same or higher quality.
The total power consumption can be reduced by about 20% compared to mechanical pulp of the same freeness obtained by multi-stage refining of chips or wood blocks that have not undergone any mechanical deformation in the conventional method. The degree of refining that can be made into paper is 50 to 200 ml CSF for RMP, and 50 to 200 ml for CRMP.
The amount is approximately 400 ml CSF, 50 to 200 ml CSF for TMP, and 50 to 400 ml CSF for CTMP, and is processed to the above-mentioned freeness by refining in two or more stages (usually two or three stages). WC Frazier and GJ Williams press wood in the direction of the fiber axis prior to refining at the Canadian Pulp and Paper Association (CPPA) January 1981 Annual Conference PrePrint A105-A111 However, their method and effect differ from the present invention in the following points. In other words, since they use the same refining method as the conventional method, the amount of energy consumed to achieve the same freeness is rather high, which is a step backwards in terms of energy conservation. Therefore, when refining pressed wood, the energy saving method of the present invention can be used, for example, in order to save energy by stopping refining at a pulp freeness (200 ml CSF) that is higher than the pulp freeness (100 ml CSF) obtained by the normal method. This method is fundamentally different from the method of optimizing allocation. EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited by these in any way. Furthermore, Figure 1 of the attached drawings shows Example 1 (marked with a circle).
Power consumption (KW hours/ton) (horizontal axis) and Canadian standard freeness for Comparative Example 1 (● mark)
It is a graph showing the relationship between CSF (ml) (vertical axis). FIG. 2 shows Example 2 (marked with a circle) and Comparative Example 2.
(● mark) is a graph similarly showing the relationship between power consumption and CSF. Example 1 TMP method A 150t press was used as the press device. The first stage of the refining equipment uses a 12-inch pressurized refiner (motor 45KW, rotation speed 3000rpm).
A 12-inch normal pressure refiner (motor 35KW, rotation speed 3000 rpm) was used for the second and third stages.
Note that these refining devices were also used in the following examples. The sample tree species is pine radiata. In the press stage, a 6 cm x 3 cm and 2 cm thick wood block is pressed in the axial direction of the wood fibers at a pressure of 1500 kg/cm ² .
Pressed for 10 seconds at room temperature. The power consumption of this press is 20KW hours/ton. In the refining stage (see Figure 1), 1
The power consumption of each stage is (A) 160KW/ton and (B)
At 200KW/ton, the power consumption required to reach 100ml of Canadian Standard Freeness (CSF) is:
(A) was 2050KW hours/ton, (B) was 2150KW hours/ton, while in the case of the conventional method (normal chip) (C), it was 2700KW hours/ton. Totaling the power consumption of the press stage, (A) is 2070KW hours/ton, (B) is 2170KW hours/ton, and the energy saving rate is 23% for (A) and 20% for (B). In addition, in the conventional method (normal chip), if the power consumption in the first stage is reduced and the subsequent refinement is performed under the same conditions, CSF cannot reach 100ml as shown in (D). The pulp quality is the same as in the conventional method, as shown in Table 1. Example 2 TMP method A hammer mill was used as the press device. The sample is a fir chip. The chips were processed in a hammer mill and those that passed a 15mm diameter screen were accepted and sent to the next TMP stage. The power consumption in the hammer mill was 25 KW hours/ton. At the refining stage, as shown in Figure 2,
The power consumption of the first stage is 200KW hours/ton.
The power consumption to reach 100ml of CSF in 3-stage processing is
It was 2025KW/ton. Normal method is 2765KW
hour/ton. Therefore, the total power consumption of the hammer mill is 2050KW/ton, which is 26
% energy saving rate. The pulp quality is equivalent to that of the conventional method as shown in Table 1. Example 3 TMP method A 150t press was used as the press device. In the press stage, a block of pine radiata measuring 6 cm x 3 cm and 2 cm thick is loaded with 750 kg/each in the axial and transverse directions of the wood fibers.
cm ² for 10 seconds each at room temperature. The power consumption required for both presses was 20KW/ton. In the refining stage, the power consumption of the first stage is 230KW/ton, and the 3-stage processing consumes CSF100
The power consumption to reach ml was 2300KW hours/ton. Total power consumption including press stage is 2320KW
hour/ton, which is an energy saving rate of 14% compared to the 2,700KW hour/ton of the normal method. The pulp quality is the same as shown in Table 1. Example 4 RMP method Using a 150t press, a block of pine radiata measuring 6cm x 3cm and 2cm thick was compressed at 750Kg in the axial direction of the wood fibers.
Pressed for 10 seconds at room temperature with a pressure of ^cm2 . This power consumption is 10KW hours/ton. In the refining stage, the power consumption of the first stage is
The power consumption is 220KW hours/ton, and the power consumption to reach 100ml of CSF in three stage processing is 1650KW hours/ton, while in the normal method it is 2050KW hours/ton. Total power consumption including press stage is 1660KW
hour/ton, resulting in an energy saving rate of 19% compared to the conventional method. As shown in Table 1, the pulp quality is the same except for the higher tension. Example 5 CTMP method Using a 150t press, a block of loblolly pine measuring 6 cm x 3 cm and 2 cm thick was pressed in the axial direction of the wood fibers at a pressure of 750 Kg/m ² at room temperature for 15 seconds. The power consumption in this case is 15KW hours/ton. In the refining stage, during the first stage refining, an aqueous Na ₂ SO ₃ solution (added as Na ₂ SO ₃ in an amount of 7% by weight of absolute dry wood) was added by being press-fitted between the refiner plates. The power consumption of the first stage is 245KW/ton, and the 3-stage processing consumes CSF100
The power consumption required to reach ml is 1900KW hours/
That's a ton. Therefore, the total power consumption including the press stage is 1915KW/ton, which is less than the conventional method.
The power consumption required to reach 100ml of CSF is
Since it is 2450KW/ton, the energy saving rate is 22%. As for the pulp quality, as shown in Table 1, the tightness and specific tear strength are slightly increased, and the tear length is the same. Example 6 CTMP method A eucalyptus block measuring 6 cm x 3 cm and 2 cm thick was pressed into a wood fiber method using a 150 t press at a pressure of 750 Kg/cm ² at room temperature for 15 seconds. This press stage consumed 15KW hours/ton of electricity. In the refining stage, an aqueous solution of Na ₂ SO ₃ (addition of 7% Na ₂ SO ₃ by weight of bone dry wood) was added by press-fitting between the refining plates in the first refining stage. The power consumption of the first stage is 300KW/ton, and the power consumption required to reach 100ml of CSF in three stage processing is:
It was 2100KW/ton. Therefore, the power consumption including the press stage is 2115KW/ton. On the other hand, in the normal method, the output is 2700KW/ton, resulting in an energy saving rate of 22%. As shown in Table 1, an improvement in pulp quality was observed.

[Table] Note: Power consumption in the production of compressed deformed chips or compressed deformed wood blocks.
It is possible to achieve an energy saving rate of around 10%, which can be said to have a significant impact on mass-produced products such as pulp.
Moreover, it must be said that it is unexpected that this is possible with a simple operation as in the present invention, and that the quality of the obtained pulp does not deteriorate. Therefore, the effects of the present invention can be said to be particularly remarkable.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between power consumption and Canadian standard freeness in Example 1 and Comparative Example 1. FIG. 2 is a graph showing the relationship between power consumption and Canadian standard freeness in Example 2 and Comparative Example 2.

Claims (1)

[Scope of Claims] 1. In the production of paper-formable pulp by multi-stage refining of compressed deformed chips or compressed deformed wood blocks in two or more stages, the power consumption of the first stage of refining is calculated to be 5 to 50% of the total refining power consumption.
A method for producing mechanical pulp, characterized in that the pulp is reduced to 15%. 2 The total power consumption of refining is 1200 ~
2500KW hours/ton (Canadian standard freeness)
Claim 1, which is (based on 100ml of CSF)
A method for producing mechanical pulp as described in Section 1. 3 First stage refining power consumption is 60~
The method for producing mechanical pulp according to claim 1, wherein the output is 375KW/ton. 4 Mechanical pulp manufacturing methods are RMP, CRMP,
The method for producing mechanical pulp according to any one of claims 1 to 3, which is either TMP or CTMP method.