JPS6314119B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an apparatus for squeezing pulp that is made of long fibers such as bast fibers and is easily twisted. In the paper industry, in the process of pulping natural plant fiber raw materials such as wood, liquid extraction equipment such as screw presses are generally used to separate and recover cooking liquor from cooked pulp or to concentrate waste paper etc. It is used. A screw press consists of a case with a hollow section of circular cross section and a spiral blade that rotates with its outer periphery in contact with the inner wall of the case.A solid substance containing liquid is supplied from one end of the case, and the spiral blade rotates. It has the effect of squeezing the solids while transferring them to the other end of the case by rotation, and to increase the squeezing effect, the axis of the spiral blade is usually made gradually thicker from the supply side to the discharge side, or the spiral lead is used. is made smaller toward the discharge side, and the transfer volume decreases as the transfer volume progresses in the transfer direction. In addition, a hole or slit is provided from the inner wall of the case to communicate with the outside of the device in order to discharge the liquid squeezed out by the squeezing action. However, among the raw materials for natural vegetable fibers, long-fiber pulps such as bast fibers such as hemp, kozo, and mitsumata have extremely long fibers, and in order to separate the liquid after cooking, they accumulate and are left to drain naturally. The only option was to use a compressor that applied a load from above. Processing using a continuous squeezing device such as the screw press has been considered impossible unless the fibers are cut in advance because the fibers are twisted in the form of strings or ropes, resulting in poor squeezing efficiency. An example of a conventional manufacturing process for long fiber pulp such as bast fiber is shown in the attached FIG. 4. The flax purchased is generally flax waste, and its fiber length is 50 to 70 mm.
It is press-packed and twisted into a lump. In some cases, flax is purchased from the factory where the fibers have been cut into fibers of around 30 mm, but they are cut using dry cutting equipment at the factory (pre-cutting refers to rough cutting before cutting finely with a beater). ), the number of steps increases by one, and the problem of disposing of the generated dust arises. Furthermore, when put into a batch-type digester (a spherical pot is generally used), flax cut into short pieces becomes bulky, reducing the amount of processing per batch. Therefore, preliminary cutting is often not performed. After cooking, the flax is stirred in the chemical solution, and as a result, the fibers twist and gather together, forming strings and even ropes. rotary juice extraction device,
For example, when the liquid is squeezed using a screw press, the binding of the fibers will further progress. Moreover, the spiral blades of the screw press tear the string-like or rope-like fibers, which increases power consumption. Due to the occurrence of twisting, both the extraction efficiency and the throughput decrease. Generally speaking, the pulp after cooking is divided into upper and lower parts called a squeezer.
The liquid is fed into a liquid squeezing device consisting of a set of endless belts and squeezed, but the squeezing efficiency is not very good because the amount of pressure is small. After that, the fibers remain twisted into a string-like or rope-like mass,
It is thrown into the beating beater. In the beating beater, the material is diluted with a large amount of water, washed during circulation, and cut with a drum-shaped cutter. Final fiber length 2-3mm
It becomes unbleached flax pulp. The problem here is the first
In addition, due to insufficient squeezing in the previous process, residual black liquor (contains chemical solution and lignin eluted from the fibers)
The problem is that the liquid is diluted, making recovery of the chemical solution and waste liquid treatment difficult. Secondly, since the fibers are cut into pieces of 2 to 3 mm while circulating the bulk fibers, it takes time to cut and wash the fibers, making it difficult to cut uniformly, and it consumes a lot of electricity. It is. As mentioned above, in the production of long fiber pulp such as bast fibers, it is important to eliminate the unique phenomenon of fibers twisting together into string-like or rope-like shapes and to extract enough liquid. However, this is a major technical issue that needs to be resolved, including improving the productivity of the entire process, stabilizing quality, and even addressing pollution issues. As a result of extensive research into squeezing equipment for long fiber pulp such as bast fibers, the present inventor has developed a system that utilizes rotating spiral blades in Screw Plus, which has high squeezing efficiency for general wood pulp. It has been discovered that if a cutter is provided to express the liquid while cutting, the efficiency of squeezing the liquid can be further improved, and preliminary cutting can also be performed.Based on this knowledge, the present invention has been completed. The squeezing device of the present invention, which is equipped with a cutting function for long fiber pulp such as bast fibers, includes a case having a hollow section with a circular cross section, and a case that rotates with the outer periphery in contact with or in close proximity to the inner surface of the hollow section. In a liquid squeezing device consisting of a spiral blade, cutouts are provided at appropriate intervals along the entire length of the spiral blade, and each end face of the spiral blade is formed at an acute angle with respect to the rotation direction at the cutout portion. A rotating blade is provided, and a fixed blade forming a shearing mechanism is attached to the inner wall of the case in correspondence with the rotating blade. The present invention will be explained with reference to the drawings. FIG. 1 shows an embodiment of the liquid squeezing device of the present invention. The outer periphery is in contact with a case 1 having a cylindrical hollow part and its inner wall 2,
The liquid-containing solid material is supplied from a supply port 4 provided at one end of the case 1, and a discharge port 5 at the other end of the case 1 is supplied by the rotation of the blades 3. It is squeezed while being transported towards. As shown in the figure, the shaft core of the spiral blade 3 gradually becomes thicker from the supply side to the discharge side.
Since the helical leads become smaller towards the discharge side, the solids are effectively squeezed by reducing the transfer volume in the direction of transfer. The liquid squeezed out by the squeezing action is discharged to the outside of the device through a number of holes (including slits) 6 provided in the inner wall 2 of the case 1. The shape of the hole 6 is determined by the solid matter, the properties of the liquid to be discharged, and the operating conditions of the device (rotation speed, pressure, temperature, concentration, etc.). In the present invention, notches 7a, 7b, 7c, etc. are provided at appropriate intervals over the entire length of the spiral blade 3, and each end face of the blade at the notch has an acute angle with respect to the rotation direction X, as shown in the cross section of FIG. Rotating blade 8 forming α
a, 8b, 8c... and fixed blades 9a, 9b, 9c... correspondingly constituting a shearing mechanism are attached to the inner wall 2 of the case.In addition to the original squeezing function of the screw press, the squeezing process This is a liquid squeezing device characterized by having the function of cutting the fiber raw material found in FIG. 3 shows an example of how the fixed blade 9 is attached. In addition, in the embodiment, as a means for effectively squeezing the solids, the central part of the spiral blade 3 is gradually made thicker toward the discharge side, or the lead of the spiral is made smaller as it goes toward the discharge side. However, a similar liquid squeezing effect can also be obtained by gradually decreasing the inner diameter of the case and the outer diameter of the spiral blade from the supply side toward the discharge side. FIG. 5 shows an example in which the squeezing device of the present invention is applied to a manufacturing process of long fiber pulp such as bast fibers. Flax waste having a fiber length of 50 to 70 mm is processed in the digester without changing its length and fed into the squeezing device of the present invention.
In this squeezing process, the fiber length is reduced to approximately 1/2, or approximately 30 mm.
(However, the present invention is not limited to this cut fiber length.) It is then sent to the beater,
The cleaning and cutting loads on the device are greatly reduced. The result is unbleached flax pulp with a fiber length of 2 to 3 mm. The following table shows a comparative example of the liquid squeezing effect between the liquid squeezing device of the present invention and a conventional squeezer. Squeezers in conventional equipment hardly perform the liquid squeezing function. With the liquid squeezing device of the present invention, a large amount of liquid can be squeezed.

[Table] The effects of the liquid squeezing device of the present invention are listed below. (1) The liquid squeezing device of the present invention mainly presses the fibers with spiral blades and squeezes the liquid using the compressive force generated, but the device itself has a cutting function and squeezes the fibers while cutting them. By liquid,
It is now possible to process long fiber pulp such as bast fibers, which was previously impossible to process. In other words, it is possible to process pulp that not only has long fibers but also tends to twist into strings or ropes in liquid. This made it possible. (2) By using the squeezing device of the present invention in the process of treating long fiber pulp such as bast fibers, the following effects can be obtained. (a) Preliminary cutting is done at the same time as squeezing, so the fibers are loosened better in the beater in the next process, allowing for even, finer cuts. (b) Liquor extraction efficiency is increased, black liquor is recovered in large quantities while remaining highly concentrated, and the washing load in the beater in the next process is reduced. As a result, effects such as a reduction in processing time in the beater process, a reduction in the amount of dilution water used, a reduction in the amount of power, and a reduction in the amount of waste water to be treated are brought about. Furthermore, it becomes easier to reuse chemical solutions and to dispose of waste fluids.

[Brief explanation of the drawing]

Fig. 1 is an assembly diagram showing the internal structure of an embodiment of the liquid squeezing device according to the present invention, Fig. 2 is a cross-sectional view along the rotation direction of the end face of the spiral blade of the device of Fig. 1, and Fig. 3 is a Fig. 1 is a cross-sectional view of the case of the apparatus at -, Fig. 4 is a flow sheet showing an example of the conventional manufacturing process of long fiber pulp such as bast fiber, and Fig. 5 is a sectional view of the case of long fiber pulp such as bast fiber. It is a flow sheet showing an example in which the liquid squeezing device of the present invention is applied to the manufacturing process of. DESCRIPTION OF SYMBOLS 1... Case, 2... Inner wall, 3... Spiral blade, 4... Supply port, 5... Outlet port, 6... Hole, 7
a, 7b, 7c...notch, 8a, 8b, 8c...
Rotating blade, 9a, 9b, 9c...fixed blade.

Claims (1)

[Claims] 1. In a liquid squeezing device consisting of a case having a hollow part with a circular cross section and a spiral blade rotating in contact with or close to the outer periphery of the inner surface of the hollow part, the entire length of the spiral blade is Notches are provided at appropriate intervals across the length, and in the notches, rotating blades forming an acute angle with respect to the rotational direction are provided on each end face of the spiral blade, and a fixed blade that constitutes a shearing mechanism is attached to the inner wall of the case in correspondence with the rotating blades. A liquid squeezing device equipped with a cutting function for long fiber pulp such as bast fiber.