JPS60231890A - Apparatus for producing pulp from sawdust and treatment of sawdust - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for producing pulp from sawdust and a method for processing sawdust.

BACKGROUND OF THE INVENTION In many regions it is possible to obtain significant quantities of sawdust and similar fiber components necessary for the production of paper pulp. Although it is possible to produce paper pulp from such raw materials using conventional techniques, they are expensive, cumbersome, and have a very narrow range of application. For example, a typical processing system that can be used to produce chemical pulp from sawdust is described in U.S. Pat.
s Pa5s the 500゜000Tons Pe
This system includes an expensive gas phase feeder and maintains a gas phase at near atmospheric pressure above the digester.

[Means for Solving the Problems, Actions, and Effects] According to the present invention, a method and apparatus are provided that eliminate the need for a gas phase feeder in a conventional sawdust treatment system, thereby reducing maintenance and making it possible to perform various treatments. It becomes possible to select. In the present invention, the sawdust is passed through an upward flow digester,
It can be processed in a downflow digester with a hydraulic vessel or with a superatmospheric gas phase. This is extremely temperature stable, which is highly desirable in all circumstances.

The term sawdust as used herein includes sawdust containing wood components and similar cellulose particles, which are sufficiently fine to react during processing to form very small particles. This is in contrast to methods in which large chopped cellulose particles, such as wood chips, are reacted during processing.

The important point of the sawdust treatment process in the present invention is that it is possible to pump the sawdust slurry to a concentration that can actually be treated. Thus, it has been found that, in accordance with the present invention, it is possible to pump slurries of sawdust containing about 10-25% solids, preferably 15-22%. This pumping is described in U.S. Pat.
No. 10゜337, and the trademark (IMC$1
Ka of Glens Falls, New York as a pump
myr ) nc, and commercially available fluidized bed, high speed, degassing, centrifugal pump pumps (fluidizino, hi.

h 5peed, degassing, centrif
ugal pumps) and related systems. Pumping a slurry of sawdust with such a high concentration (e.g. 10-25%) is necessary, as fine particles tend to behave solidly against more flexible materials such as pulp. is surprising. Furthermore, the sawdust slurry is not strained thoroughly;
Furthermore, even sawdust slurry containing about 10% solids is actually semi-solid.

According to the method of the present invention, sawdust is processed by mixing sawdust into a liquid with a solid content of about 10-25% (about 15-25%).
(preferably 22%), and this slurry is pumped without dilution to a processing step to finally produce pulp.

During the treatment process, the slurry is heated (indirectly
Or fluidized bed mixer (fluidizing m1xer)
), the slurry is introduced into a vertical vessel in which it is chemically treated, after which the slurry is discharged. Preferably, this vessel is an upflow vessel, through which the slurry is pumped undiluted and to the top by a fluidized bed, high speed, centrifugal pump. On the other hand, the vessel can also be an upflow vessel, either a hydraulic vessel or a vessel with a superatmospheric gas phase.

Inside the container, the lignin in the sawdust is easily dissolved or actually dissolved through chemical treatment.

For example, it is possible to carry out sulfite treatment inside the container,
The slurry discharged from this vessel is passed through a refiner to become mechanical pulp. Alternatively, the slurry can be krafted into a kraft pulp in a container. Regardless of the treatment process, if the sawdust is mixed with the liquid, it is preferable to mix the sawdust with the low-pressure steam and the treatment liquid, and then introduce the sawdust into a vertical chute and pump the slurry from the bottom of the chute. The slurry is maintained at approximately the same concentration (ie, approximately 10-25% concentration) throughout the entire process without phase separation (solid/liquid).

The apparatus according to the invention includes means for mixing sawdust into a liquid and
337, a vertical digester, a conduit between the digester and the pump, and a heating device for indirect or direct heating prior to introduction into the digester. It is equipped with A conduit, a valve means in the conduit, and a heating device are interposed between the pump and the digester, and the slurry is forced to flow through the digester by being pumped.

The present invention efficiently uses sawdust to produce pulp.
Its main purpose is to perform simple and various types of processing. These and other objects of the invention will become apparent upon examination of this specification.

[Embodiment] FIG. 1 shows a preferred embodiment of the apparatus according to the present invention, for producing kraft pulp. This example・
The device is a normal horizontally arranged steaming vessel 12 (
a low pressure feeder mounted on top of a steam mixer (known as a steam mixer) with a horizontally arranged mixing screw;
Vessel 12 has a vent 1 with adjusted steam release pressure.
4 is a provision. Sawdust is sent from the source to the feeder 10
After that, it is introduced into a vessel 12, where it is mixed with a chemical solution to form a slurry. This chemical solution contains white liquor recovered from the Kraft process chemical solution, and low-pressure steam is further introduced into this vessel 12. Vessel 12
The slurry discharged from the vertical chute 16 (ver.
tical ctlute), but may alternatively be routed to a conduit connected directly to the pump, as described below. The liquid level is maintained within the chute 16 by a conventional radiation level gauge 18 which controls a valve means 20 in a conduit 21 extending from the bottom of the chute 16. Preferably, a chemical solution such as white liquor is introduced into the chute 16.

The above-mentioned members 10, 12, 14 and 16 mix sawdust into the chemical solution, and the concentration of the solid part is about 10-25% (about 15%).
-22% is preferred). The slurry has this consistency at the bottom of the chute 16, at which the pump 22 is located.

Although pump 21 is shown schematically in FIG. 1, it may also be provided with a gas handling device, which degassing device is described in U.S. Pat.
, No. 337, and this patent number is shown for reference.

The pump 22 is a fluidized bed, high speed, degassing, centrifugal pump (f
luidizing, hioh 5peed, dega
centrifugal pump). Generally, the pump impeller is 2000-340
The slurry is turned into a fluidized bed by rotating at Orpm. This pump is commercially available under the trademark "MC" Pump from KamVr, Inc., Glensft, New York, and Kamyr AB, Karlstad, Sweden.

Connected to conduit 21 is a heating device 24 and a vertical container or digester 26 . In the embodiment shown in FIG.
The heating device 24 includes a mixer and mixes the high pressure steam directly into the slurry. Various configurations of this mixer are covered by the first Canadian patent.
, 102,604, and this mixer is a fluidized bed mixer (fluidizina m1xer). The mixer that can be used with this heating device is trademark 44M.
Kamyr, Inc. and Kamy as CIT mixer
rSold by AB.

The container or digester 26 is of the continuous type, and in the embodiment of FIG. 1 is of the upflow type with a conventional evacuation mechanism 28 at the top. In the digester 26, the slurry is chemically treated. The kraft delignification process takes place in the digester 26, where the white liquor introduced during the sawdust slurry process keeps it alkaline, typically 9-24% dry raw material.
It is in the range of Na2O. The heating device @24 brings the slurry to the optimum cooking temperature, which is typically 140-175°C. Pump 22 pumps the slurry, typically 600-12
The slurry is maintained at this pressure in the digester 26 for a predetermined period of about 30-130 minutes. These values are merely exemplary and may vary to some extent depending on the nature of the sawdust and the subsequent final pulping process.

The embodiment of FIG. 2 is generally similar to that described in FIG. 1, but indirect heating means 30 are used to bring the slurry to the optimum cooking temperature, and the digester 40 is of the downward flow type. be.

Vertical vessel 30 is connected to pump 22 via conduit 21 and is preferably indirectly heated with a movable screen as shown in US Pat. No. 4,368,628. In such an indirect heating vessel with a movable screen, the slurry is maintained at the pressure delivered by the pump 22 without being diluted. Pump 3 from container 30
The liquid drawn in step 2 passes through the steam heater 34 and returns to the container 30 through the inlet 35 for circulation. Therefore, the slurry is indirectly heated while passing through the container 30 and is heated at the discharge section 31.
An amount approximately equivalent to the discharged liquid is replenished from the inlet 35, so that the concentration of the slurry does not change significantly even while it is being heated in the container 30. The slurry is discharged from a conventional discharge mechanism 36 and introduced via conduit 37 into the upper portion 38 of the downflow digester 40 . The produced pulp is discharged from the bottom of the digester 40 through a conventional discharge mechanism.

According to the present invention, the downward flow digester 40 can be applied to many applications. Preferably, the downflow digester 40 is hydraulically filled. Alternatively, this upper part can be in a superatmospheric gas phase, in which case the gases that do not condense are discharged via vent 43. In either case, the temperature stability in the treatment process can be significantly increased compared to conventionally used atmospheric pressure digesters.

The apparatus used in FIGS. 1 and 2 is primarily useful for producing chemical pulp. The device in Figure 3 is a mechanical pulp,
It is particularly useful when producing chemical mechanical pulp (CMP) or chemothermomechanical pulp (CTMP). In this embodiment, the chemical treatment vessel 46 is considerably smaller than the digesters 26, 40 because the delignification process is not carried out completely within this vessel. Typically, sulfite is added to the slurry in vessel 46 (e.g., by mixing the sulfite with sawdust in a mixing device), and the slurry discharged from vessel 46 into discharge line 47 is typically passed to glue refiner 48. The produced mechanical pulp is sent to conduit 49.

Generally, sodium sulfite with a pH of 9-10 is
A less strong pretreatment solution (mild pr
treatment liquid), and the internal temperature is approximately 130-170°C. However, in some cases, simply heating the slurry with high-pressure steam to about 1 1 0-1 50°C (such as in fluidized bed mixer 24) without adding any chemicals can facilitate fibrillation in Rifagona 48. (fibrilizatin) You can also ask for thermomechanical pulp (TMP).

According to the method of the invention, sawdust is treated (in steam mixer 12 and chute 16) by mixing the sawdust with a chemical solution to form a slurry with a solids temperature of about 10-25%, preferably 15-22%; Without dilution, this slurry is pumped using a fluidized bed/high speed/centrifugal pump 22 up to the final pulp processing step. In the processing step, the slurry is heated to an optimal temperature and introduced into a processing vessel. This heating may be by direct heating, such as mixing high pressure steam directly into the slurry using a steam mixer 24, or by a pressure diffuser 30 (Dressure
heat indirectly, such as by using a diffuser.

In the treatment vessel, the slurry undergoes some chemical treatment. This chemical treatment only facilitates the dissolution or disintegration of the gluegenin within the sawdust, where mechanical pulp is ultimately produced.

The final kraft pulp is obtained by dissolving the lignin from the sawdust in a container using a chemical process. Finally, the pulp is discharged from the container, i.e. container 26, 40 or 46. The chemical treatment takes place during upward or downward flow through hydraulic pressure.

The pulp is treated with sulfur dioxide in the container 46, and the discharged pulp is finally litz-fined in a beam refiner 48. In the container 26, kraft processing is carried out, and kraft pulp is finally produced.

Therefore, according to the present invention, a simple, effective and versatile method and apparatus for processing sawdust into pulp is provided. According to the present invention, the problems of the gas phase feeder and the associated high costs and maintenance are solved, and the range of application of the system is expanded.

While the present invention has been described in terms of the most practical and preferred embodiments, it will be obvious that many modifications may be made within the scope of the invention, including all equivalent methods and apparatus.

[Brief explanation of drawings]

1 is a diagrammatic representation of an embodiment of an apparatus according to the invention for carrying out an embodiment of the method according to the invention, and FIG. 2 is a diagrammatic representation of a second embodiment of an apparatus according to the invention. , FIG. 3 schematically shows a third embodiment of the device according to the invention. 10...Low pressure feeder, 12...Steaming vessel, 14...Vent, 16...Chute, 18...
...Liquid level needle, 20...Valve means, 21...Conduit, 22
...Pump, 24...Heating device, 26.40...
Digester, 28... Discharge mechanism, 30... Heating means, 32... Pump, 31... Discharge unit, 34...
Steam heater, 35... Inlet, 36... Discharge mechanism, 3
7... Conduit, 38... Upper part, 46... Container, 47
...Discharge pipe, 48...Refiner, 49...Conduit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] (1) A means for mixing sawdust into a liquid to form a slurry, a pump, and a method for chemically treating the slurry internally to facilitate the dissolution of lignin in the sawdust, or for dissolving the lignin. a conduit connecting the digester and the pump and having valve means therebetween;
heating means disposed in the conduit to heat the slurry sent from the pump to the digester to bring the slurry in the digester to an optimal processing state, the pump comprising:
Fluidized bed, high speed, degassing, which is connected to a heating means and mixes sawdust into the liquid and pumps the sawdust slurry.
a centrifugal pump, the pump being coupled to the digester through the conduit and heating means to pass the slurry through the digester, with only the conduit, valve means and heating means being coupled between the pump and the digester; A device for producing pulp from sawdust, characterized by: (2. The device according to claim 1, wherein the digester is an upflow digester having an inlet at the bottom and an outlet at the top, and the conduit and the pump are coupled to the inlet at the bottom of the digester. (3) In the device according to claim 1,
The digester has an inlet at the top and an outlet at the bottom;
A digester comprising a downward flow hydraulic vessel, said conduit and pump being coupled to an upper inlet. (4) In the device according to claim 1,
The digester comprises a tIII acid process digester, and a refiner is coupled to the outlet side of the digester. (5) In the device according to claim 1,
The means for mixing the sow dust into the liquid includes a horizontally arranged steam mixer, a low pressure feeder that supplies the sow dust to the steam mixer, a means for feeding the liquid and low pressure steam to the steam mixer, and an outlet of the steam mixer. The fluidized bed, high speed, gas handling,
A device in which a centrifugal pump is coupled to the bottom of said chute. (6) Mix sow dust into the liquid so that the solid part is about 10-
A method for processing sawdust to obtain a slurry containing 25% of sawdust, the method comprising a step of pumping the slurry without diluting it to a final pulp manufacturing process. (7) In the method described in claim 6,
The treatment steps include (i) heating the slurry to an optimal treatment temperature, (ii) pumping the heated slurry into a continuous treatment container, and (1ii) chemically treating the slurry in this container to facilitate dissolution of the glue genin in the sawdust. or dissolved;
(iv) discharging the treated slurry from the vessel. (8) In the method described in claim 7,
step (ii) introducing the slurry into the bottom of the upflow vessel and flowing the slurry upwardly by said pumping;
Step (tv) is carried out by discharging the treated slurry from the top of the vessel, step (i) is delivering the slurry to an indirect heating vessel and introducing the heated liquid under pressure into the indirect heating vessel. The liquid is discharged from the container in an amount approximately equivalent to the heated liquid introduced, and the discharged liquid is heated and circulated to be used as a heated replenishment liquid. A method performed by circulating heated slurry from a container to the inlet of a processing container. (9) In the method described in claim 7,
the vessel is a vertical upward flow vessel that maintains a gas phase pressure significantly higher than atmospheric pressure at the top; step (ii) is carried out by supplying slurry directly to the top of the vessel by the pump; A method in which step (iv) is carried out by discharging from the bottom of the container. (10) In the method according to claim 9, the step (iii) is carried out by a sulfite method, and further,
A method comprising step (V), sending the slurry discharged from the container in step (V) to a refining step, and refining the sawdust slurry to produce mechanical pulp.