SE429874B - SET AND DEVICE FOR MANUFACTURING FIBER MASS AND LIGNOCELLULOSALLY MATERIAL - Google Patents

Description

829 ~ fi943-2 10 15 20 25 30 35 during the grinding process, especially during its initial stage.

The miters are largely composed of lignin, which on heating and rising temperature gradually softens and changes from a solid to a relatively liquid state. This ratio is used in a number of mass production processes for reducing the electricity required for this purpose, whereby the material is heated before decomposition by means of freshly supplied fresh, or steam generated during the decomposition process.

By enclosing the grinding means of a pressure-tight housing, decomposition or grinding of supplied preheated material is made possible while maintaining favorable and elevated pressures and temperature conditions for the process. The fibrous mass produced during decomposition is discharged from the pressurized mill housing to a receiving device, in which, likewise, an overpressure equal to that maintained in the outlet zone of the mill housing is maintained. or slightly lower The receiving device in which the fibrous mass and the same vapor supplied with the mold is separated, is provided with a device for discharging the fibrous mass from the receiving device while maintaining the vapor pressure therein, and without major simultaneous outflow of steam with the fibrous material. g The steam separated in the receiver has previously been used for preheating the material at atmospheric conditions up to approx. 100 ° C before the material's pressure-tight feed into the preheater directly connected to the mold and working under pressure. The material has been heated by adding fresh pressure steam to the preheater, or by more energy-intensive decomposition processes with backflowing steam from the inlet zone of the maldon.

The object of the invention is to be able to carry out the milling under favorable high pressure and temperature in a grinding method of an initially known nature (see, for example, Swedish patent 413,601) and to be able to recycle the supplied electricity resp. the steam energy for preheating the material in the preheater to the highest possible temperature. This is achieved essentially in that the transfer of the material not only to the preheater but also from the latter to the grinder 10 15 20 25 35 8200943-2 takes place through a vapor-tight conveyor and that a higher meadow resp. gas pressure is created in the maia apparatus than in the preheater in such a way that the steam emanating from the mahppmetmitiii receiving means by means of this higher pressure is transferred further to the preheater and there is responsible for preheating to over 1000 of the material. The invention also comprises a device suitable for carrying out the method. At the same time as the maintenance according to the invention can be carried out under the most favorable pressure and temperature conditions, the steam energy supplied during the maintenance is recovered in the preheater with a very significant reduction of the energy consumption for carrying out the process. Due to the relatively high temperature to which the fibrous material is exposed, the invention is particularly suitable for the production of porous and hard fibreboards, so-called board, where the requirements for the whiteness of the fibrous mass are smaller. At the same time, the decomposition of the fibers during the release of fibers in such products does not have to be driven so long and the process as a whole is less energy-intensive in the mapping apparatus. This again means that additional energy in the form of fresh pressure steam is required in the device to achieve the intended pressure distribution for the steam transmission in the system and the high preheating temperature in the preheater. According to the invention, the costly charge rate is reduced to a minimum by using the pressure steam which can be recovered from the receiving device.

It will be appreciated that the pressure obtained from the outlet zone of the maidone with the addition of a small amount of fresh boot at the inlet zone of the separated maidone can be transmitted through the turbo power of the maidone and during decomposition. such a level that the temperature and degree of treatment of the mold from the separated preheater to the material is the same, but differs only insignificantly from what has previously been achieved with the addition of a fresh boot to the maidon directly (open) preheated heater.

Characteristic of the invention can also be said to be that the raw material before it, by means of a basically pressure-separating feed device, transferring to the mold working under elevated pressure and temperature, is subjected to a preheating to a temperature exceeding 10,000, but not exceeding that maintained in the outlet zone of the maldon, the amount of steam required for this preheating being supplied from the outlet zone of the maldon via a pressurized fiber separator.

The invention will be described in more detail below with reference to the embodiment shown in the accompanying drawings as an example.

Fig. Partly in section, of a plant for carrying out 1, shows more or less schematically a side view, the method according to the invention.

Fig. 2 shows the grinding apparatus included in the plant and the pressure-separating conveyor connected to it, on a larger scale and in a vertical section. In the drawings, 10 denotes an inlet funnel for the raw material, such as wood chips, which is fed by a screw conveyor 11 to a preheater 15. The material is thereby compressed by the screw 12 of the conveyor, which is driven by a rotor 19, and forms a vapor-impermeable material plug. The degree of compression is controlled by a pneumatic back pressure device 13 operating with a conical valve cone 14 resting against the feed material plug.

Upon passage of this valve cone, the material plug dissolves and the material falls into the vertical preheater 15, where a material level is maintained, which gives the desired residence time in the preheater vessel. This material level is maintained by a level regulator 16 influencing the feed. The material heated in the preheating vessel 15 is discharged at the speed of the pre-screw 12 by means of the actuator 19. the bottom of the heater by means of a conveyor 18 via a tight transfer tube 20 to the inlet of a material providing a substantially vapor-tight transfer of the material from the preheater 15 to the grinder or disc refiner 24. The conveyor 22 comprises, in the same manner as the feed conveyor 11 in the exemplary embodiment, an internally tapered tube in the direction of the material flow, i which works To the outlet side of the pipe if required for the execution of the process, a back pressure screw 26 of the same shape. is connected, means 27 Lex.in the form of a pipe spout, in which are mounted flaps 28, which are actuated by piston servomotors 30, so that they can be pivoted into the inner channel 32 of the spout, which forms a suitable cylindrical continuation of the material compressing the outlet area of the screw feeder and upon engagement thus the flow area of this channel decreases.

Thereby, the degree of compression of the material supplied to the mold 24 and preheated can be varied to the desired degree while simultaneously extruding the accompanying liquid (water) through perforations 31 in the compression tube to a housing 35 tightly connected casing 35, from which the extruded liquid is diverted via a pipeline 90 to a container 92, the overpressure of which is equal to or close to the meadow pressure maintained in the inlet pipe 20, by a pipeline 94 connecting the container 92 to the inlet pipe 20. The liquid level in the container 92 is controlled by a level sensor 100 and a regulator 98 controlled therein for a drain 96 from the container ~ fitted valve 97.

The grinding apparatus or defibrotator 24 comprises grinding discs enclosed in a housing 36, in the exemplary embodiment a stationary grinding disc 38, which is fixedly connected to the housing, and a grinding disc 40 which is supported by a shaft 44 driven by a motor 42.

After the starting material has been compressed in the conveyor 22 resp. the counterpressure means 27 continues it further through an internally suitably cylindrical tube 70 whose free end is located close to the rotating grinding wheel 40. This tube is then eccentrically arranged relative to the axis of rotation of the grinding wheel 40 to facilitate the highly compressed material plug disassembly before the material is inserted into the slot 48. between the grinding wheels. The plug can be disassembled suitably against one or more wings 72 on the grinding wheel 40 opposite the mouth of the eccentric tube 70. Through a line 74 8290943-2 10 15 20 25 30 35 water can be added to the material when it is introduced into the grinding gap 48 as a replacement for the water type squeezed out of the conveyor. A conveyor of the type now described is known from Swedish patent specification 419,659.

Between the motor 42 and the rotating grinding wheel 40 a servomotor 45 is arranged in a known manner, which as e.g. of patent 179,337 by means of an axially displaceable but non-rotatable pressure piston transmits the pressure of a hydraulic medium via shaft bearings to the rotating shaft 44 to produce the required high milling pressure for the grinding surfaces radially outwardly flowing in the gap 48 between the milling discs malgodset. A drain line 50 is connected to the grinding wheel housing 36, through which the fibrous mass produced in the grinding apparatus is maintained, while maintaining overpressure, resp. blown over to a cyclone-type receiving container 80, preferably in which fiber and steam are separated from each other.

In the exemplary embodiment, the separated fiber is discharged from a substantially pressure-tight rotatable valve 82 to a receiving conveyor 84, where the fibrous mass accompanying moisture is evaporated 89 for possible use in another atmosphere operating under atmospheric pressure and diverted through a collecting cover part of units included in the plant. The pressure level in the receiving container 80 is regulated to the desired value by means of a differential regulator 85, which by sensing means 54 and 55 via lines 81 and 83 senses the pressure in both the housing 36 of the grinder and in the receiving vessel 80 and automatically maintains a pressure difference between them, in the exemplary embodiment usually 0.1 ~ 0.7 kg / cm 2. The steam pressure in the grinder housing can amount to 7-12 kg / cm The temperature of the steam at the outlet from the grinder housing can be 115 ä 125 to 150 ä 17000 to which the material is heated in the preheater apart from the inevitable pressure and temperature drops on the way to the preheater.

A valve 52 may be provided in the conduit 50 between the grinder 24 and the receiving vessel 80. With this valve the exit velocity of the fibrous material from the grinder housing can be regulated with respect to the total length of the conduit 50.

The material supplied to the preheater 15 is heated 2. by means of steam discharged from the receiving vessel 80 through a line 86, which has a pressure level below that maintained in the mill housing only with the pressure drop which required for transporting the treated fibrous material from the mill housing 36 via the receiving vessel 80, up to the preheater 15, usually 0.1 - 2.0 kg / cm 2.

The grinding wheel housing 36 is supplied through lines 120, 124 and 122 fresh steam before and possibly after the passage of the grinding material through the grinding gap 48 between the grinding discs. The task of the fresh steam is to maintain the pressure required for the process in the mill house. This pressure is balanced by means of a regulator 110, which acts on a valve 112 located in the line 122 and senses the pressure next to the drain of the grinding housing via a line 114. The supplied fresh steam is transferred together with steam generated during the grinding of supplied electrical energy to the preheater 15 with only a minimal lowering of pressure and temperature.

The distribution of the meadow supply through the two lines The line 122 only needs to be connected at extremely low steam generation between the grinding discs in order to then be able to maintain the lines 122, 124 are regulated by means of valves 123, 125. desired pressure resp. preheating temperature in the vessel 15. the 122 can be dispensed with in many cases.

The arrangement with separated pressure vessels, i.e. preheater 15, grinder 36 or receiving vessel 80, thus enables the material supplied to the process to be heated to a temperature in the preheater 15, which closely coincides with that in the grinding wheel housing as its inlet is maintained, using only pressure steam recovered from the process.

By utilizing the turbo power of the grinding member 4D and the electrical energy supplied during decomposition, the pressure maintained at the outlet of the grinding housing 36 can be raised to a level which enables the steam recirculated to the preheater 15 to be given a pressure higher than the meadow pressure maintained. In this arrangement, the material supplied to the mold 24 can thus be brought to the same temperature as in previous embodiments could only be achieved by supplying fresh steam to the preheater, a preheating which results in considerable (40-80%). ) saving of heat energy for the heat treatment of matter.

Any excess steam generated by the steam is dissipated by a steam 88, whereby the vapor pressure maintained in the system is thus kept constant, while at the same time a smaller pressure difference is required between the housing 36 and the receptacle 80 is maintained at the desired level. A valve 99 is arranged in the line 88, the setting of which can be monitored by the regulator 85.

The invention is of course not limited to the embodiment shown but can be varied in the broadest sense within the scope of the basic idea. Thus, a gas such as air can be entrained in the vapor atmosphere to provide the intended pressure and temperature distributions in the sieved system.

Claims (4)

8-200943-2 Patent claims A method of producing fibrous pulp from lignocellulosic raw material comprising preheating the material in a preheater (15) by steam, then grinding the preheated; the material under elevated steam resp. gas pressure between relatively rotatable grinding means (38; 40) in a grinding apparatus (24) to fibrous mass, which blows from the housing of the apparatus by means of the steam resp. the gas to a separator (80) which is likewise under vapor pressure and in which the vapor is separated from the pulp, characterized in that the transfer of the material not only to the preheater but also from the latter and the grinder takes place by a vapor-tight conveyor, and that a higher steam resp. gas pressure is created in the grinder than in the preheater in such a way that the steam leaving the grinder to the receiving means by means of this higher pressure is transferred on to the preheater and there is responsible for preheating to over 1000 of the material. 2. A method according to claim 1, characterized in that fresh steam resp. gas is supplied to the material in the housing of the grinding apparatus (24) before and possibly also after the passage of the material between the grinding means (38, 40), whereby the fresh steam resp. the gas is subjected to a pressure resp. temperature that ensures the heating of the material in the preheater to over 10006, preferably 125 - 150%. Apparatus for carrying out the method according to claim 1 in the production of fibrous pulp from lignocellulosic raw material, comprising a preheater (15) which is fed to raw material through a transfer-tight transfer means (11) under pressure and steam for preheating the material, a screw conveyor (22) for transferring the preheated material to a grinding apparatus (24) with relatively rotatable grinding means (38, 40) arranged in a housing and an outwardly sealed receiving device (80), to which the ground fiber the mass is blown by means of steam present in the grinding housing, which is separated in the receiving device from the fibrous mass, characterized in that the screw conveyor is designed for vapor-tight transfer under overpressure of the material both from the preheater and to the grinder from the grinder, takes place through a pressure-tight dewaterer (31, 35) and further to the mapping device via a pressure-relieving pressure means (27) and that the receiving means is through a n line (86) connected to the preheater, so that then in the maïappar aïstras resp. tiiiföres steam resp. gas of higher pressure and temperature than in the receiver and the preheater, this steam resp. gas is transferred through the line to the preheater and there is responsible for the heating of the material to over 10000. 4. Device according to claim 3, characterized in that the grinding apparatus (24) is arranged to be supplied with fresh steam resp. gas of such overpressure and temperature that it is at least deïvis responsible for the preheating of the material in the preheater (15) to the intended temperature before the transfer to the mai apparatus.