Cyclon Purification Plant. The present invention relates to a hydrocyclon plant for separation of suspended solid from a liquid. The plant is particularly adapted to separate suspended particles from water, for instance filler particles in effluence from paper mills or to remove a part of the filler being present in the white water system in a paper machine. As the plant exhibits large capasity, is compact and easily maintained it is well suited in all cases in which particles in a liqui can be removed by means of a hydrocyclon. The plant is well suited when it is desirable to remove fine particles from a liquid. This is particularly so when in the plant is utilized a cyclon of the type being disclosed in Norwegian , Application No. 83.0058.
Hydrocyclons being used in the present devise are well known and a short account can be found inter alia in Encyclopedia of Chemical Technology, 2nd edition volume 4 pp. 747-748.
Hydrocyclons are well adapted for removing of fine particles being present in low or medium solid concentrations. Due to share forces being present in the vortex in the hydro¬ cyclons, separation is not effected by the centrifugal force alone but the form of the particles exerts a certain effect. Hydrocyklons have thus been used in the pulp and paper indust in order to separate fibers of different length.
Normally a hydrocyclon consists of a rotation symmetrical, elongated hollow body which under working condition is arranged in a vertical position and the upper end of which is provided with at least one tangential directed inlet through which the liquid to be treated is injected with high velocity in such manner that a vortex stream is created in the hydrocyclon.
In the upper part of known cyclons is a centrally arranged outlet opening, the cross sectional area of which is larger than the combined cross sectional area for the inlet openings. Through the upper outlet opening is exhausted the injected liquid now fully or partly derived of solid particles
In the lower part of the hydrocyclon is arranged a central outlet opening, the cross sectional area of which is less than the cross sectional area for the inlet openings and serves as an outlet for a minor part of the injected liquid which at the lower part of the hydrocyclon is enriched with respect to solid matter.
The rotation symmetrical hollow body which in the length direction can be designed conically such as shown in US paten 2.920.761, or can be sylindrical in the upper part with a conical lower part such as shown in Norwegian Patent No. 144.128. In order to adapt the hydrocyclons for different purposes and in order to improve the. efficiency, different modifications of such hydrocyclons have been suggested, for instance with respect to th_e inlet for the liquid to be treated, as shown in the above mentioned Norwegian Patent or with modification of the outlet for the part of the liquid enriched with solid matter, such, as shown in US patent No. 4.309.238.
Particular outlets for the purif ed liquid is shown in US patent No. 4.259.180 and French, patent No. 1.518.253.
Different types of hydrocyclons are inter alia disclosed in the US patent No. 4.265.47Q, 4.28Q.902, 4.305.825, 4.267.048 as well as in US patent No. 4.272.26Q vhich discloses a cyclon for separation of solid particles from gasses.
It is commonly known to couple a number of cyclons in parallell, that is the inlets of the hydrocyclons are connect to a common pipe and the outlets from the cyclons from the purified liquid is connected to a common pipe whereas the respective outlet for the liquid phase being enriched with respect to the particles is exhausted via a common pipe connected to the lower part of the hydrocyclons. Such a plant comprising a number of hydrocyclons is spacious and it is difficult to obtain equal conditions for all cyclons with the result that not all cyclons in such a battery of cyclons will -work under optimal conditions.
By means of the present invention is provided a compact plan by means of which it is possible to have a number of cyclons working under essential equal conditions in that all cyclons are enclosed in a chamber in such manner that all the cyclon are provided with the liquid to be treated under the same pressure.
The invention shall be eluciated with reference to the enclo drawings, in which:
Fig.l shows a section through a plant according to the invention.
Fig. 2 discloses one of two essentially identical partitions which partly are used to divide the chamber, in which the hydrocyclons are arranged, to compartments and partly to secure the cyclons within the chamber.
Fig. 3 shows a horisontal projection of the upper part of a cyclon with a particularly designed inlet as well as a detai of the fastening device for the. cyclon to the partition.
In fig. 5 is shown how the lower part of the cyclon extends through the lower partition, which is designed in the same manner as the upper partition.
In fig. 1 is shown how a number of hydrocyclons 1 are arrang within a common chamber 2. Water 4 or the liquid to be treate is injected from a not shown feed pump to th.e compartment 15 via the inlet 3, whereby the cyclons 1 are surrounded by water 4 under the preferred pressure, hence the water is injected to the inlet dyse 5 of each, hydrocyclon. All the hydrocyclons will thus be provided with water or the liquid at essentially the same pressure. In the upper part of the compartment 15 is arranged a close fitting partition 6 provid with holes 7 for each cyclon 1. The partition 6 is removable connected to the chamber such that all cyclons, if necessary simultaneously can be lifted out of the chamber.
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A tight fitting lid 8 comprises the upper part of the chamber 2 such that under the lid is formed a compartment 9 being separated from the water underneath the partition 6. The outlets for purified water from all cyclons opens up in the compartment 9 being formed between the lid 8 and the partitio 6. The purified water or the accept is exhausted via the outlet tube 10.
In the lower part of the chamber 2 is arranged a further partition 11. The lower partition 11 is prererably arranged tight fitting to the wall of the chamber 2 and is provided with corresponding holes 7 as in the plate 6 and through which the lower outlets 12 of the hydrocyclons extends in a tight fitting manner such, that the water 4 in the compartme 15 being defined between the two partitions 6 and 11 respec¬ tively cannot penetrate to the void 13 underneath the partition 11.
From the reject outlet 12 of th.e cyclons is" exhausted a minor part of the injected liquid. As usual for hydrocyclons said part being enriched with respect to the solid phase of par¬ ticles being separated from the feed water injected to the inlet tube 3. The enriched phase or reject is removed from the void 13 via the outlet tube 14.
The cyclons 1 being arranged in the chamber 2 can be of a type known per se being secured to the partition 6 and the inlet 5 which, is arranged underneath the partition such that water 4 being introduced via the inlet 3 can be forced into the inlet 5 of each, cyclon. The cyclons 1 are prefer-^ ably of the type described in Norwegian Patent Application No. 83.0085. Said cyclon is characterized by a large capacity and ability to separate very small particles. The liquid being introduced to the cyclon 1 through, the inlet 5 is lead into a rotation forming chamber 40 being defined between the inner wall of th.e cyclon 1 and a guiding tube 2Q having a conical form and with, a conicity in the range 4-1Q . The rotating liquid stream is forced down through, the cyclon and returns as usual in its lover part and the ascending,
purified liquid or accept is lead out through an annular outl 120 being defined between the guide tube 20 and especially designed body 110 to the chamber 9 and out of the plant via the outlet 10. 5
In the preferred used cyclon the liquid is not exhausted through a central outlet, such as usual for common cyclons, but through the annular outlet 120 being formed between the conical tube 20 and the centrally arranged body 110. The 10 body 110 is secured to a director plate 90 which directs the stream into the compartment 9 above the partition 6 and out through the outlet 10.
In order to aid replacement of the cyclons 1 the same are 15 fastened by means of a fastening device 50, which in fig. 1 is shown to comprise a through bolt 51, a collar 52 engaging the flange 53 on the cyclon 1. The collar 52 being secured by means of the bolt 51 thus support the cyclon 1 which firml is held engaged against the collar 52 by means of a collar 20 54 being secured by means of the nut 55.
In the lower part the cyclon 1 is passed through, correspondin holes 7 in the partition 11, as indicated in fig. 5. In order to prevent leakage of the injected liquid 4 to the compartmen 25 under the partition 11 a ceiling ring is provided in a groove in the partition, for instance an O-ring as indicated in fig. 5. Other ceiling and fastening devices is of course possible.
In a hydrocyclon plant according to the present invention
30 containing 85 hydrocyclons of the preferred type the height of the chamber was 3,3 m and the diameter 1,37 . The dia¬ meter of th.e individual cyclons was approx. 7,6 cm.
V
The device was used to separate solid particles from sea wate
35 and the number of particles ofthe sea water introduced as wel as the accept water was determined by means of a "COULTER COUNTER TAII". The sea water was introduced at a pressure of 2,1 bar at which pressure each cyclon had a capasity of 150 1/min. , that is the total capasity of the plant was approx. J
12 750 1/min. The separation efficiency of the plant is apparent from the following table:
COULTER COUNTER TAII
Liquid: Sea water Place: NUTEC, Bergen
Efficiency
Particle Number of Number of Percentage Accumulated diametre particles particles of particles percentage, urn per ml of per ml in removed particles feed water accept larger than water
1.0-1.25 22436 17072 23.9 75.4
1.25-1.6 10578 8095 23.5 76.7
1.6-2.0 6268 4357 30.5 78.1
2.0-2.5 4651 2971 36.1 79.5
2.5-3.2 2765 1529 44.7 81.6
3.2-4.0 1727 759 56.1 83.8
4.0-5.1 1084 299 72.4 86.0
5.1-6.4 707 107 84.9 87.6
6.4-8.0 423 58 86.3 88.1
8.0-10.1 233 26 88.8 88.6
10.1-12.7 100 Q - 91.0 88.5
12.7-16.0 39 6 84.6 87.1
16.0-20.2 19 3 84.2 88.8
20.2-25.2 2 0 100.0 100.0
25.2-32 1 0 100.0 100.0
As apparent an excellent separation and high capacity is obtained by means of the new cyclon plant.