DE1561702C

DE1561702C - Process for the separation of elongated or flat impurities with a low specific weight from fiber suspensions by hydrocyclones. '

Info

Publication number: DE1561702C
Application number: DE19671561702
Authority: DE
Inventors: Nils Roland Skutskär; Ahlborg Nils Knut Falun; Grundelius (Schweden)
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-11-20
Filing date: 1967-11-20
Publication date: 1973-01-25

Description

nahezu vollständiges Abtrennen der leichten Verunreinigungen bzw. Splitter möglich ist, und zwar unter Aufrechterhaltung eines normalen Durchsatzes im Hydrozyklon, d. h. unter praktisch vollständiger Ausnutzung seiner Nennkapazität. Vorzugsweise wird die aus dem zentralen Spitzenauslaß abgezogene Fraktion in einem Hydrozyklon in an sich bekannter Weise einem weiteren Sortiervorgang unterworfen. Hierbei sind verschiedene Kaskadenschaltungen von Hydrozyklonen zur kombinierten Abtrennung der leichten und schweren Verunreinigungen möglich. Die kleine Fasermenge, die bei dem erfindungsgemäßen Verfahren als leichte Fraktion anfällt und in der die leichten Verunreinigungen angereichert sind, kann in bekannter Weise gesiebt oder weiterzerfasert werden.almost complete separation of the light impurities or splitter is possible, while maintaining a normal throughput in Hydrocyclone, d. H. with practically complete utilization of its nominal capacity. Preferably the fraction withdrawn from the central tip outlet in a hydrocyclone in a manner known per se subjected to another sorting process. Here are various cascade connections of hydrocyclones for the combined separation of light and heavy impurities possible. The little one Amount of fiber that is obtained as a light fraction in the process according to the invention and in which the light impurities are enriched, can be sieved in a known manner or further shredded.

Das erfindungsgemäße Verfahren wird im folgenden an Hand einiger in den Zeichnungen dargestellter Ausführungsformen und an Hand einiger Zahlenbeispiele näher erläutert. ■' _; The method according to the invention is explained in more detail below with the aid of some embodiments shown in the drawings and with the aid of some numerical examples. ■ '_;

In den Fig. 1 bis 4 sind als'Ausführungsbeispiele verschiedene Zyklontrennanlagen mit verschiedenen Kombinationen von Zyklonabscheidern schematisch dargestellt;1 to 4 are exemplary embodiments different cyclone separation plants with different combinations of cyclone separators schematically shown;

F i g. 5 zeigt in graphischer Darstellung die Ergebnisse, die man bei erfindungsgemäßem Betrieb mit den in F i g. 1 bis 4 dargestellten Anordnungen sowie bei Splitterabtrennung in einer einzigen Stufe erhält.F i g. 5 shows a graphic representation of the results obtained with operation according to the invention the in F i g. 1 to 4 arrangements shown as well as with splinter separation in a single stage.

In den Fig. 1 bis 4 bedeutet C den Einlauf der Fasersuspension, D den Ablauf einer Endfraktion, die ini wesentlichen frei von Splittern ist, und E den Ablauf der anderen Endfraktion, die den größten Teil der Splitter enthält. Für jede der vier Ausführungsformen gibt die/entsprechende Zeichnung die für die jeweilige Ausführungsform erfindungswesentliche Führung und kaskadenartige Verzweigung bzw. Rückkopplung der Zu- und Abläufe der zusammengeschalteten Abscheider wieder.In FIGS. 1 to 4, C denotes the inlet of the fiber suspension, D the discharge of an end fraction which is essentially free of splinters, and E the discharge of the other end fraction which contains most of the splinters. For each of the four embodiments, the / corresponding drawing shows the guide and cascade-like branching or feedback of the inflows and outflows of the interconnected separators that are essential to the invention for the respective embodiment.

Von den in Fig. 5 gezeigten Kurven geben die Kurven I bis IV für die in F i g. 1 bis 4 gezeigten Anlagen und Linie V für einen einzelnen Hydrozyklon jeweils den funktionalen Zusammenhang zwischen α und ρ bzw. zwischen b und /-wieder. Hierbei bedeutet:Of the curves shown in FIG. 5, curves I to IV for those in FIG. 1 to 4 shown plants and line V for a single hydrocyclone in each case the functional relationship between α and ρ or between b and /-again. Here means:

α das Verhältnis zwischen der Anzahl von Splittern in der Endfraktion E und in dem Zulauf C der Anlage; α the ratio between the number of splinters in the end fraction E and in the feed C of the plant;

ρ den Splitterabtrennungsgrad für jeden einzelnen Zyklonabscheider, d. h. das Verhältnis zwischen der Anzahl der Splitter, die am Kopfauslaß (Leichtfraktionsausiaß) abgezogen werden, und der am Einlaß zugeführten Anzahl von Splittern; ρ the degree of splinter separation for each individual cyclone separator, ie the ratio between the number of splinters that are drawn off at the head outlet (light fraction outlet) and the number of splinters fed in at the inlet;

b das Verhältnis zwischen der Menge an guten Fasern in der Endfraktion E und im Zulauf C der Anlage; b the ratio between the amount of good fibers in the end fraction E and in feed C of the plant;

r den Faserverlustgrad pro Zyklonabscheider, d. h. das Verhältnis zwischen der Menge an guten Fasern, die am Kopfauslaß mitabgezogen werden, und der' dem Einlaß zugeführten Menge an guten Fasern. r is the degree of fiber loss per cyclone separator, ie the ratio between the amount of good fibers drawn off at the head outlet and the amount of good fibers fed to the inlet.

Die Werte von a, p, b und r können hierbei beispielsweise .in Prozent angegeben sein.The values of a, p, b and r can for example be given in percent.

Aus den in F i g. 5 angegebenen Kurven können die a- und Z?-Werte der Gesamtanlage abgelesen werden, die verschiedenen Werten von ρ und r entsprechen. Wie Versuche gezeigt haben, können für den einzelnen Hydrozyklon bei erfindungsgemäßem Betrieb ein SplitterabtrennungsgraJ ρ = 70 % und ein Faserverlustgrad τ — 20 % als realistische Werte angenommen werden. Hierfür ergibt sich theoretisch, d. h. unter Vernachlässigung von möglichen Verlusten in der Anlage:From the in F i g. 5, the a and Z? Values of the entire system can be read off, which correspond to different values of ρ and r. As tests have shown, a fragment separation rate ρ = 70% and a fiber loss rate τ - 20% can be assumed as realistic values for the individual hydrocyclone when operated according to the invention. Theoretically, i.e. neglecting possible losses in the system, this results in:

Bei der Anlage gemäß Fig. 1 (Kurve I): ° a — 34 und b — 0,8, d. h., die Endfraktion E enthält 34 Va der Splitter und 0,8 % der bei C zugeführten Fasern;In the plant according to FIG. 1 (curve I): ° a - 34 and b - 0.8, ie the end fraction E contains 34 Va of the splinters and 0.8% of the fibers fed in at C;

Bei der Anlage gemäß F i g."2 (Kurve II): a — 59 und b = 1,2, d. h., die Endfraktion E enthält 59 °/· der Splitter und 1,2 % der bei C zugeführten Fasern;In the installation according to FIG. 2 (curve II): a - 59 and b = 1.2, ie the end fraction E contains 59% of the splinters and 1.2% of the fibers fed in at C;

Bei der Anlage gemäß F i g. 3 (Kurve HI): a = 84 und b = 5,9, d. h., die Endfraktion E enthält 84 V» der Splitter und 5,9 % der bei C zugeführten Fasern;In the case of the system according to FIG. 3 (curve HI): a = 84 and b = 5.9, ie, the final fraction E contains 84 V »of the splitter and 5.9% of the fed with C fibers;

Bei der Anlage gemäß F i g. 4 (Kurve IV): a =94 und b=l,&, d.h., die Endfraktion £ enthält 94 % der Splitter und 1,8 % der bei C zugeführten Fasern.In the case of the system according to FIG. 4 (curve IV): a = 94 and b = 1, &, ie the end fraction £ contains 94% of the splinters and 1.8% of the fibers fed in at C.

Daß die oben angenommenen Werte ρ — 70 °/o und τ = 20 % vorsichtig angenommene realistische Werte sind, die in Vielen Fällen erheblich günstiger liegen werden, zeigen die folgenden Beispiele.The following examples show that the values ρ - 70 % and τ = 20% assumed above are carefully assumed realistic values which in many cases will be considerably more favorable.

Versuch AAttempt a

1000 Gramm eines absolut trockenen Sulfitzellstoffes, welcher tausend ausgezählte Verunreinigungen in Form von ausgedehnten Splittern enthielt, wurden erfindungsgemäß in einem Hydrozyklonabscheider bei einer Stoffkonzentration von 0,5 % derart behandelt, daß 950 Gramm der Fasermenge als schwere Fraktion abgezogen wurden, während der Rest von 50Gramm als.leichte Fraktion erhalten wurde. Die Anzahl der Splitter in den beiden Fraktionen wurde gezählt, sie betrug in der leichten Fraktion 850 und in der schweren Fraktion 150. Das entspricht einem Splitterabtrenngrad ρ = 85 % bei einem Faserverlust r = 5 %. Bezogen auf die trokkene Fasersubstanz, änderte sich die Splitterkonzentration von ursprünglich 1000/kg auf 17 000/kg in der leichten Fraktion und 158/kg in der schweren Fraktion.1000 grams of an absolutely dry sulfite pulp, which contained a thousand counted impurities in the form of extensive splinters, were treated according to the invention in a hydrocyclone separator at a substance concentration of 0.5% in such a way that 950 grams of the fiber was removed as a heavy fraction, while the remainder was 50 grams als.light fraction was obtained. The number of splinters in the two fractions was counted; it was 850 in the light fraction and 150 in the heavy fraction. This corresponds to a degree of splinter separation ρ = 85% with a fiber loss r = 5%. In relation to the dry fiber substance, the splinter concentration changed from the original 1000 / kg to 17,000 / kg in the light fraction and 158 / kg in the heavy fraction.

Versuch BAttempt B

Ein Gegenversuch wurde nach dem üblichen Verfahren durchgeführt, wobei 50 Gramm der Fasermenge als schwere Fraktion entnommen wurden, während der Rest von 950 Gramm als leichte Fraktion anfiel. Die Anzahl der Splitter der beiden Fraktionen wurde gezählt Sie betrug 950 in der leichten und 50 in der schweren Fraktion. Es ergab sich also keinerlei AnreicherungseffektA counter-test was carried out according to the usual procedure, taking 50 grams of the fiber amount as the heavy fraction, while the remainder of 950 grams as the light fraction incurred. The number of splinters from the two fractions was counted. It was 950 in the light one and 50 in the heavy fraction. So there was no enrichment effect whatsoever

Wenn auch die gemäß Versuch A erzielten Werte bei einem einzelnen Hydrozyklon nur in Ausnahmefällen auch im technischen Maßtab realisiert werden können, so läßt sich doch mit kaskadenartigen Anordnungen mehrerer Hydrozyklone gemäß Fig. 1 bis 4 eine optimale Abtrennung der Splitter bei sehr geringem Faserverlust mit dem erfindungsgemäßen Verfahren erreichen.Even if the values obtained according to test A for a single hydrocyclone are only in exceptional cases can also be realized on a technical scale, it can be done with cascade-like arrangements several hydrocyclones according to Fig. 1 to 4 an optimal separation of the splinters with very achieve low fiber loss with the method according to the invention.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

1 v '■ - ■ ■■■ - ■■■ 2 ■■■ · ■' · ■ pulp, since the fiber bundles are not · completely bleached in the normal patent claims: bleaching processes. The "splinters" also affect the strength of the

1. Process for severing elongated paper or pulp web.

5 Since the specific gravity of the named impurities

according to specific gravity, such as B. of splinters do not clean themselves from that of the fiber material or

or fiber bundles from fiber suspensions differed by little, they are considerably heavier

Hydrocyclones with peripheral inlet, central to separate as the so-called severe impurities

Tip outlet and central head outlet, cleaning that z. B. from grains of sand, soot, heavy

characterized in that the pressure io ren rind particles or the like. For sorting

and / or area ratio at the outlets of the suspended fibrous materials different spe-

type is set so that the larger part ·, min-. specific weight and especially for travel

at least 60% of the fed pulp, mostly from pulp fiber suspensions of heavy

Tip outlet and the remainder at the head outlet. Impurities are known in hydrocyclones

is pulled. '' 15 of the usual design, which has a completely or partially conical

2. The method according to claim 1, characterized in that the separating chamber has a peripheral inlet and is marked with that those from the central tip central head outlet at the wider end and central outlet withdrawn fraction exist in a hydro-tip outlet at the narrower end, to cyclone turn to someone in a manner known per se. With such hydrocyclones the -head is Sorting process is subjected. ao outlet the outlet for the light fraction and the

Top outlet the outlet for the heavy fraction; '''"■ · ■■ · ■ ^r " ^: when cleaning fiber suspensions, hydro-

So far, cyclones have only been operated in such a way that the

■ ■ 'cleaned fiber material as a light fraction at the head outlet

25 and the impurities as a heavy fraction on

The invention relates to a method for peeling off the tip outlet. By setting The can separate elongated or flat areas of the cross-sections at the two outlets cleanings with low specific gravity, such as the degree of separation changed and the present z. B. of splinters or fiber bundles from fiber ratios can be adapted (chemical engineering suspensions by hydrocyclones with peripheral technology, 1953, pp. 331 to 341). If found too Inlet, central tip outlet and central head, that the withdrawn heavy fraction besides the outlet. . '. ■: ... . also one called "heavy" impurities

In the production of chemical pulp with a certain proportion of light impurities, ie, splinters are-nowadays very high demands are made on the purity of the product (Paper Trade Journal, October. A large 35 1952, p. 33), so it is but in the paper and line part that is present in the finished product. Pollution technology generally recognized that with hydrocleaning originate from discolored bark stands - cyclones of the normal type mentioned above and divide or bundle fibers. These fiber bundles can occur with the previously known mode of operation, for example, in that certain sufficient separation of the light contaminants parts of the wood is not possible due to their particularly firm 4 °. A way out of this difficult structure when producing or cooking the cell is insufficiently impregnated to separate light contaminants, or that a special type of hydrocyclone is known to process the wood leading to pulp (Austrian patent 258 692), its zylinim pulp digester runs unevenly. A diametrically opposite peripheral outlet for the knots and branches, possibly with which they contain the accept and a central outlet for the surrounding wood layers, and larger pieces of wood, which has impurities, are created through the peripheral inlet and the separating process following the boiling. Because of the special design and mode of operation that have not yet been deforested or opened up to such an extent, however, the fact that they can be easily frayed, the normal output of such a hydrocyclone is limited.
sometimes separated. In the subsequent sieving, 50 In contrast, the invention is based on the object to which the pulp is generally subjected, the separation of the light-weight mentioned, further wood components and possibly impurities from fiber suspensions are separated from bark parts. Depending on how well the previously existing prejudice with hydrocyclone screens is carried out, the pulp can be of more conventional design, i.e. with a peripheral inlet and zen or less completely free of the above-mentioned central head and tip outlet.
Be impurities. However, economic considerations set a limit according to the invention, up to which the cleaning solves that the pressure and / or area ratio of the pulp can be driven by sieving. The outlets are set in such a way that the larger one. It turns out in practice that even after the part, at least 60% of the fed pulp, sieves still a greater or lesser number of 60 at the bottom outlet and the remainder at the head outlet, fiber bundles of various sizes and the like is flattened. .

In contrast to the previously practiced operation

The hydrocyclone under the term “splitter” is the accepted material at the outlet be summed up. deducted for the heavy fraction. Surprising-

These impurities, whose color is between 65 wise, was found to be the can be yellow-brown and almost black, causing splinters for the most part to be located in the abz. B. accumulate in the paper made from the pulp drawn light fraction, so that a Stains and soiling often also very extensive bleached items, in the case of multi-stage operation even