PROCEDURE AND DEVICE FOR DEGASSING FIBROUS MATERIAL SUSPENSION

The invention concerns a procedure for degassing fibrous material suspension gemäß the generic term of the requirement 1 and a device for degassing fibrous material suspension gemäß the generic term of the requirement 7.

Devices for degassing fibrous material suspension are the specialists of the industry in the best way admit and in a multiplicity of commercial writings, as for example in the DE 42 34 522 A1, in the DE 32 19 740 A1, in the WHERE 97/15717 A1 and in the US patent 5.868.905, revealed. After their name the devices are to degas fibrous material suspension.

US 4.478.615 points a device to degassing fibrous material suspension, with which a procedure of this kind is feasible. In particular in one with vacuum subjected containers as well as in the exhausting line for those, attached to it, approximately gas-free suspension in each case the pressure measured and regulated the actual level in the container.

The devices mentioned are groß e container, to which those the Papieroder board machine gashaltige fibrous material suspension which can be given up is supplied as thin mixture. The operational principle of the respective device consists of letting the gashaltige fibrous material suspension under negative pressure simmer and separating the gas thereby into a so-called gas area and from the container. Those the Papieroder board machine fibrous material suspension which can be supplied is taken against it by an opening in the tank bottom, what is naturally connected with the thought to derive as gas-free a fibrous material suspension as possible from the container. In order to maximise the degassing ability of the device, in the container by means of a pump a negative pressure is produced, whereby the gas escapes by a Unterdruckpumpe (vaccum pump) with line from the container. Beyond that the degassing ability is improved, as the supplied, still gas containing fibrous material suspension is entered by jet pipes above the level of liquid in the container, whereby the gas existing in the admitted fibrous material suspension as blisters is possibly separated already, before the admitted fibrous material suspension with the already existing fibrous material suspension comes into connection.

An overflow serves for the stabilization of the level of liquid in the container, whereby over its edge as a rule approximately a component current of about 10% of the total quantity brought into the container fließ t. It is from disadvantage that this overflow quantity is led back via long pipings again before the feed pump for the supply of fibrous material suspension into the container into the cycle. Besides the energy employment of the system is higher around this overflow quantity, than for degassing the Gutstoffmenge (approximately gas-free fibrous material suspension) is alone necessary. Besides the container becomes by the additional overflow größ it and more expensively.

The invention is the basis the task to create a procedure and a device of the kind initially specified which the well-known container costing, regelungsund more energy-efficiently operable, constructionally more simply and kostenmäß industrial union make favorably producible and besides the well-known disadvantages of the state of the art avoid.

This task becomes erfindungsgemä&szlig with a procedure; by the characteristics solved in the characteristic of the requirement 1.

This erfindungsgemäß e level regulation of the fibrous material suspension in the container makes it to completely do without the past overflow and degassing fibrous material suspension for costing possible to make energy efficient regelungsund. Furthermore it is suggested that the pressure by means of third, dominant in the removal line, which second is measured approximately fibrous material suspension of subordinate printing transmitter gas-free in direction of flow that and that over the geodetic difference to the second printing transmitter in the regulation unit a density correction of the computed actual level is accomplished in the container.

This extended level regulation makes on the one hand a faster and more exact regulation procedure possible, on the other hand one the density of the fibrous material suspension and thus that can be supervised gas content in that approximately gas-free fibrous material suspension with it.

In the case of a change of the value for the density correction can erfindungsgemäß different Maß took, however or in combination, to be seized:

• in the container the dominant pressure is changed by the source of vacuum;
• the actual level at fibrous material suspension in the container is changed by a speed adjustment of the feed pump and/or the headbox pump;
• the throughput quantity of fibrous material suspension by the container is changed by a speed adjustment of the feed pump and/or the headbox pump; and
• the retention time of the fraying off suspension in the container is changed by a speed adjustment of the feed pump and/or the headbox pump.

Further becomes erfindungsgemäß following the well-known state of the art suggested that surplus fibrous material suspension is separated over an overflow appropriate in the container and led back into the cycle.

This kind of the separation and feedback of fibrous material suspension is suitable in particular if fibrous material suspension with light impurities strengthens is present and these impurities are to be eliminated in favorable way.

Those erfindungemäß e level regulation can be consulted naturally to regulate the flow rate at surplus fibrous material suspension is it by computation or by measurement.

This task becomes erfindungsgemä&szlig during a device; by the characteristics solved in the characteristic of the requirement 7.

This in such a manner trained container including erfindungsgemäß he level regulation makes it possible to do without the past overflow completely and him thereby constructionally more simply and kostenmäß to make favorably producible industrial union. Furthermore it is suggested that in the removal line third, which second is attached approximately fibrous material suspension of subordinate printing transmitters gas-free in direction of flow that for the measurement of the dominant pressure and that the regulation unit accomplishes a density correction of the computed actual level over the geodetic difference to the second printing transmitter in the regulation unit in the container. This extended level regulation makes on the one hand a faster and more exact regulation procedure possible, on the other hand one the density of the fibrous material suspension and thus that can be supervised gas content in that approximately gas-free fibrous material suspension with it.

Erfindungsgemäß for reaching of a good density correction it is suggested that the geodetic difference between the second and third printing transmitter größ it 1 m, preferably größ it 5 m, in particular größ it 10 m, is.

In order to receive now optimal conditions for a well working automatic control loop, becomes erfindungsgemäß suggested the fact that the source of vacuum from a vaccum pump with an number of revolutions-adjustable drive unit, in particular an electric motor exists, and that the feed pump and the headbox pump an number of revolutions-adjustable drive unit, in particular, exhibits an electric motor.

Further becomes erfindungsgemäß suggested that the container exhibits an overflow, preferably a partition, over which surplus fibrous material suspension separatable and by means of at least one overflow pipe into the cycle it is reducible.

This kind of the separation and feedback of fibrous material suspension is suitable in particular if fibrous material suspension with light impurities strengthens is present and these impurities are to be eliminated in favorable way. Further characteristics and advantages of the invention result from the Unteransprüchen and the following description of preferential remark examples with reference to the design.

Show:

Figure 1:

a schematic device for degassing fibrous material suspension gemäß the well-known state of the art;

Figure 2:

a schematic device for degassing fibrous material suspension gemäß one erfindungsgemäß EN execution form.

The figure 1 points a schematic device 1 to degassing fibrous material suspension 2 gemäß the well-known state of the art. The device 1 consists of one, preferably elongated and lying cylindrical container 3 with horizontal or approximately a horizontal container axle 3,1, at least at the container 3 working source of vacuum 4 including pertinent Vakuumleitung 4,1, at least one supply line 5,1 including pertinent feed pump 5 for supplying gashaltiger fibrous material suspension 2,1 into the container 3 and a removal line 6,1 to would drive off from approximately gas-free fibrous material suspension 2,2. into a headbox pump 6 and into following ranges of one those approximately gas-free fibrous material suspension 2,2 processing machine 7, in particular a Papieroder board machine. In figure 1 is headbox pump 6 by means of removal line 6,1 separators 8, preferably vertical separators 8,1, downstream, whereby the removal line 6,1 in the long run into a headbox 9, which a wire section 10, in figure 1 a double filter molder follows 10,1, flows. A back driving line 11 leads back the surplus and approximately gas-free fibrous material suspension 2,2 into the container 3 resulting in the headbox 9. Into the container 3 the fibrous material suspension 2,1 gashaltige supplied by means of the supply line 5,1 including pertinent feed pump 5 is directly before the container 3 by at least one Cleaner stage 12 led and inferred from a Siebwasser I container 13. Gashaltige fibrous material suspension 2,1 is over a line 16 from the Stoffaufbereitung 14, exemplary by the machine vat 15 represented to the Siebwasser I container 13, and over a line 17 out in the wire section 10 resulting Siebwasser i supplied.

It should be noted that the supply of the gashaltigen fibrous material suspension 2,1 also laterally into the container 3 to take place can do, for example in the way revealed in the German disclosure writing DE-A 17 61 496 (= US patent 3.538.680). Gemäß now an overflow 18, preferably in form of a partition 18,1, is inserted to the well-known state of the art in the container 3, which is stabilized the level of liquid in the container 3 and used for the distance of on the liquid surface of the container 3 accumulated light impurities, so that it at the machine downstream, in particular a Papieroder board machine, to arrive. The light impurities fließ EN over the overflow 18 for execution 18,2 and anschließ end over a line 19 for subsequent treatment (Cleaner or sorter), where one is anxious to separate it from the fibrous material suspension 2 and to lead back the fibrous material suspension 2 into the cycle. Into figure 1 the line 19 before the feed pump 5 into the supply line 5.1 flows.

The figure 2 points a schematic device 1 to degassing fibrous material suspension 2 gemäß first erfindungsgemäß EN execution form, whereby the device mentioned 1 corresponds to the device 1 of the figure 1 in principle.

Therefore regarding the detailed description to the figure 1 one refers.

Erfindungsgemäß it is now intended that in the container 3 at least a first printing transmitter is attached 20,1 for the measurement of the pressure produced by the source of vacuum 4 pB that in the removal line 6,1 a second printing transmitter is attached 20,2 for the measurement of the dominant pressure pA1 that a regulation unit 21 for the computation of an actual level 22,1 in the container 3 from a differential pressure Δ p between first and the second printing transmitter 20,1, 20,2 is present and that the computed actual level 22,1 is adjustable over a speed adjustment of the feed pump 5 on a preferably constant target level 22,2 by the regulation unit 21.

This container 3 including erfindungsgemäß it level regulation makes it, on the past overflow for 18 possible gemäß to do without the figure 1 completely and it thereby constructionally more simply and kostenmäß to make favorably producible industrial union.

Erfindungsgemäß furthermore it is intended that in the removal line 6,1 third, which second is attached approximately fibrous material suspension 2,2 subordinate printing transmitter gas-free in direction of flow S (arrow) that 20,3 for the measurement of the dominant pressure pA2 and that the regulation unit accomplishes 21 over the geodetic difference UG to the second printing transmitter 20,2 in the regulation unit 21 a density correction DK of the computed actual level 22,1 in the container 3.

This extended level regulation makes on the one hand a faster and more exact regulation procedure possible, on the other hand one the density of the fibrous material suspension and thus that can be supervised gas content in that approximately gas-free fibrous material suspension with it.

Erfindungsgemäß the geodetic difference UG between the second and third printing transmitter is grö&szlig 20,2, 20,3; it 1 m, preferably größ it 5 m, in particular größ it 10 M.

Further the source of vacuum consists 4 of a vaccum pump 4,2 with an number of revolutions-adjustable drive unit 23, in particular an electric motor, and the feed pump 5 and the headbox pump 6 exhibit an number of revolutions-adjustable drive unit 23, in particular an electric motor.

In special arrangement (broken representation) the container 3 exhibits an overflow 18, preferably a partition 18,1, over which surplus fibrous material suspension 2 separatable and by means of at least one overflow pipe 19 into the cycle is reducible.

In the figure 2 without the detailed indication of lines and connections between the individual components of the automatic control loop one did, since they rank among the well-known state of the art in control engineering and are anyway flatly natural the specialist. Furthermore well-known rule components became, as for example Pl (Pressure Indicated) or SIC (speed Indicated control), not further describes and characterized.

In the figure 2 the represented erfindungsgemäß EN execution forms of a device 1 for degassing fibrous material suspension 2 are suitable in excellent way by execution erfindungsgemäß EN of procedure for degassing fibrous material suspension 2. of a further description erfindungsgemäß EN of procedure is here foreseen and on the general description erfindungsgemäß EN of procedure referred.

Recapitulatory it is to be noted that by the invention a procedure and a device of the kind initially specified are created, which the well-known container costing, regelungsund more energy-efficiently operable, constructionally more simply and kostenmäß industrial union make favorably producible and besides the well-known disadvantages of the state of the art avoid.