RU2233248C1 - Device for removing impurities from circulating water - Google Patents

Abstract

FIELD: treatment of water.

SUBSTANCE: device has low-velocity vortex separator, settling tank, accumulating tank, and high-velocity vortex separator, which are connected in series. The low-velocity vortex separator is mounted inside the vertical settling tank on the frame and has funnel-shaped housing provided with the spiral guiding surface for flow and pipe for discharging slam. The settling tank has collector for purified water and slam receiver provided with a device for permanent discharging of slam.

EFFECT: enhanced efficiency of purification.

2 cl, 4 dwg

Description

The invention relates to the pulp and paper industry, in particular to a device for treating reverse wash water for wood chips.

Washing wood chips before grinding is of exceptional importance in the manufacturing process of wood semi-finished products, it allows you to remove the abrasive components of wood chips, which dramatically affect the life of the grinding set. Thorough washing of the chips increases the service life of the headset disk mill up to 2500-3000 hours.

Water consumption for washing chips is approximately 30-35 m ³ per 1 ton. The problem of saving water and energy resources requires equipping pulp and paper production, including the production of wood semi-finished products, with a recycling water treatment cycle.

When using recycled water in the production, the problem arises of cleaning it from impurities, the quantitative composition of which increases with each cycle of water use.

A known installation for cleaning industrial industrial water from solid components, protected by patent DE 3700725, IPC 7 C 02 F 1/38, C 02 F 1/52, B 01 D 21/00, published. 07.21.88. The installation comprises a settling tank, a sludge dehydrator and a vortex separator. For better sedimentation of finely dispersed impurities in the settling tank, surfactants are added to the water to be purified. The coagulated sediment is removed from the bottom of the settling tank, dehydrated and sent to a vortex separator to separate the coarse phase. The light precipitate obtained in the vortex separator is sent for further purification.

The use of surfactants in the treatment of washing water for wood chips is unacceptable due to the negative impact of surfactants on the further technological process of mechanical and chemical treatment of wood.

The prototype of the claimed invention is the installation of continuous cleaning of circulating wash water for wood chips, protected by patent US 5882509, IPC 7 B 01 D 21/26, published. 03/16/99.

The water treatment plant is part of a wood chip washing machine, which also includes a wood chip separator and a screw chip dehydrator. In the waste separator, wood chips are washed from mineral and organic impurities in a turbulent stream of water created by a rotary blade mixer. In a screw dehydrator, the washed chips are separated from the washing water before being fed for further processing.

Water separated from the chips is supplied to a water treatment plant comprising a vertical settling tank, a high-speed vortex separator, and a storage tank. In this case, heavy particles (sludge) are deposited in the settling tank, which are continuously removed through a fitting in the conical bottom. Purified water enters the storage tank. Water contaminated with sludge is fed into a high-speed vortex separator, cleaned and returned to the sump.

After cleaning in a vertical settling tank and in a high-speed vortex separator, water is returned to the waste separator for washing a new batch of wood chips.

The disadvantage of the prototype is that water treatment at the first stage of treatment in a vertical settling tank is carried out without taking into account the individual ability to sedimentation of mineral and organic impurities. The mineral and organic dispersed phases are separated from the circulating water stream only at the outlet of the high-speed vortex separator, in connection with which it is overloaded with suspended solids and the degree of water purification is reduced.

The claimed invention solves the technical problem of saving water and energy resources in the production of wood products by increasing the efficiency of cleaning wash water. The result is achieved by taking into account the individual ability to sedimentation of mineral and organic impurities, the specific gravities of which differ significantly.

In accordance with the claimed invention, the separation of water from mineral and organic impurities is carried out at separate stages of purification. This approach prevents overloading of subsequent purification steps with suspended solids.

The problem is solved using the inventive installation of continuous purification of circulating water from mechanical impurities.

The installation comprises a high-speed vortex separator, a low-speed vortex separator, a vertical settling tank and a storage tank, and a low-speed vortex separator, a settling tank, a storage tank and a high-speed vortex separator form a sequential technological chain. The low-speed vortex separator contains a funnel-shaped housing, inside of which there is a spiral guide surface for flow and sludges, and the separator itself is installed inside a vertical settling tank on a trellised frame. A plate damping-distributor of the circulating water flow emerging from the low-speed vortex separator is combined with the lattice frame. The vertical sump tank contains a clarified water collector and a sludge trap equipped with a sludge flush device outside the process circuit. The sludge flush device is designed as an envelope for the sludge receiver of the spray water conduit with spray holes and an autonomous source of spray liquid. The storage tank is equipped with an additional section for purified water in a high-speed vortex separator, while an overflow of water through a semi-submersible intersection partition is possible between the tank sections.

The invention is illustrated in the drawing, which shows:

figure 1 - installation of washing wood chips, including the inventive installation of continuous purification of circulating water;

figure 2 - section of the tank-settler with a low-speed vortex separator;

figure 3 is a section along aa of figure 2;

figure 4 is a section along BB of figure 2.

A wood chips washing unit comprises a chip waste separator 1, a screw chip dehydrator 2 and the inventive continuous circulating water treatment unit, comprising a vertical settling tank 3 for an upward laminar flow with a low-speed vortex separator 5 mounted inside it on the trellis frame 4, and a vertical storage tank 6 for purified circulating water, a high-speed vortex separator 7, hydraulic pumps 8, 9, 10 and 11, pipelines 12, 13, 14, 15, 16 and 17.

The low-speed vortex separator 5 has a funnel-shaped housing 18, inside which a spiral guide surface 19 for flow is installed. In the lower part, the spiral guide surface 19 is connected to the sludge headers 20, the number of which corresponds to the number of visits of the spiral guide surface 19. In the upper part of the housing 18 of the vortex separator 5, a pipe 21 for tangential supply of circulating water is made.

The vertical settling tank 3 comprises a cylindrical body 22 with an annular vertical channel 23 for an ascending clarified flow. In the lower part of the settling tank, a sludge collector 24 is made with an autonomous sludge flushing device through a drain pipe 25 into a mud hopper (not shown). In the above example (figure 2), the sludge trap 24 is made inclined. The sludge flush device is made in the form of an envelope for the sludge receiver of the spray pipe 26 with a supply pipe 27 and spray holes 28 distributed evenly along the length of the water conduit. At the outlet of the vortex stream of circulating water from the low-speed vortex separator 5 in the housing 22 on the trellis frame 4 there is installed a plate damping-distributor of the upward flow 29. In the upper peripheral zone of the housing 22, a clarified water collector 30 is installed to collect clarified water with a drain into the by-pass collector 31.

In the vertical storage tank 6, a vertical semi-submersible intersectional septum 32 is made, dividing the storage tank into sections B and D for water clarified at different stages of treatment. The storage tank in the upper part of the housing is equipped with nozzles 33 and 34 for supplying purified water to sections B and G, respectively, in the lower part of the housing - nozzles 35 and 36 for collecting purified recycled water from sections B and G, respectively, with a nozzle 37 for draining excess water and a pipe 38 for communicating the air cavity of the storage tank with the atmosphere.

The high-speed vortex separator 7 is equipped with a device 39 with valves for controlled removal of sediment.

The inventive installation for continuous purification of circulating water works as follows.

After washing the wood chips in the waste chip separator 1 and separating it from the chips in the screw dehydrator 2, the washing water contaminated with mineral and organic impurities flows through the drainage sieve of the dehydrator into the pipe 12. Due to hydrostatic pressure, the washing water flows to the inlet of the tangential pipe 21 of the vortex low-speed separator 5. Moving along the spiral guide surface 19 of the funnel-shaped housing 18, the wash water flow acquires a vortex turbulent character. The vortex nature of the flow destroys the structure of the wash water and contributes to the accelerated precipitation of the heaviest, coarsest mineral impurities, such as stones, coal, cement, concrete particles, coarse sand, etc. Under the influence of centrifugal forces, coarse dispersed mineral impurities are primarily thrown to the periphery of the funnel-shaped housing 18, along the spiral grooves of the spiral guide surface 19 and along the sludge headers 20 are directed by gravity to the sludge collector 24. The housing 18 of the low-speed separator 5 is made in the form of a truncated inverted cone to maintain the value of the centrifugal inverted cone component of the flow rate unchanged in height of the chamber.

At the outlet of the low-speed separator 5, the vortex of circulating water flows around the housing 18 from the bottom and enters the annular vertical channel 23. Upon changing the direction of the flow to the vertical, additional mineral impurities are separated from the wash water and they precipitate. The cross-sectional area of the channel 23 exceeds the cross-sectional area of the chamber of the low-speed vortex separator 5, due to which the flow of recycled water slows down, the process of precipitation of mineral impurities is enhanced.

At the entrance to the annular channel 23, the reverse wash water encounters in its way a plate damping-distributor of the upward flow 29, placed on the lattice frame 4 in such a way that the flow loses energy when it collides with the surfaces of the plates and is divided into laminar upflows uniformly distributed around the circumference of the ring channel 23. At the same time, the inertial forces of the circular motion of impurities are quenched.

The plate-type damping-distributor of the upward flow 29 serves as an additional obstacle for the flow of suspended particles to the collector 30 of clarified water. In this case, a finely dispersed phase of mineral impurities precipitates, such as, for example, fine-grained sand. Above the sludge collector 24 of the settling tank, a zone of renewable filtration layer of condensed material is formed, which additionally cleans the ascending wash water from fine particulate matter.

From the sludge collector 24, the deposited mineral impurities are continuously washed off with water into the discharge nozzle 25 and pumped out by the pump 9 into the sump hopper. The sludge flushing fluid enters the sludge collector 24 from an autonomous source through the supply pipe 27 through the spray pipe 26 and is sprayed through openings 28 evenly distributed along the perimeter of the sludge collector 24. This ensures the continuous removal of deposited impurities from the circulating wash water circuit without stopping the process.

Mineral impurities separated from the wash water in the first purification step are not involved in the further circulation of the wash water.

The degree of purification of wash water in the first stage of the inventive installation reaches 65-70%, depending on the fractional composition of impurities coming from wood chips. The fractional composition may vary depending on the season of wood harvesting.

Recycled flushing water clarified in the first stage of treatment, containing light organic impurities, is poured through the upper threshold of the clarified water collector 30 and by gravity through the pipe 31 and pipe 13 enters the inlet 33 of section B of the storage tank 6.

The second stage of purification of the reverse wash water occurs in a high-speed vortex separator 7. Through the intake pipe 35 of the storage tank 6 and the pipe 16, the water flow is pumped by the pump 11 into the high-speed vortex separator 7, where it is subjected to high-speed swirling and, under the action of centrifugal forces, is cleaned of light organic impurities such as particles of wood bark, bast, rot, etc. Concentrated impurities are collected in the lower part of the high-speed vortex separator and sent through the device 39 adjustable drainage sediment sent to the hopper-sump. The degree of purification of wash water in the second stage of the inventive installation reaches 75-80%.

The flushing water purified in the second stage is fed through line 14 to the inlet 34 of section G of the storage tank 6, from where it is taken by pump 10 through the outlet pipe 36 and pumped into the wood chips separator 1 to flush the next batch of chips through the pipe 15.

A two-section reservoir tank 6 of purified water with a variable working level allows you to control the balance of the water supply for flushing and through the overflow system 17 - the regulation of the amount of circulating water in the circuit.

The invention improves the degree of purification of reverse wash water, reduces the use of fresh water while reducing the weediness of the semi-finished wood product, increasing the service life of nozzles of a high-speed vortex separator and grinding headset for wood chips.

Claims (3)

1. Installation of continuous purification of circulating water from mechanical impurities, comprising a vertical settling tank, a high-speed vortex separator and a purified water storage tank, characterized in that it further comprises a low-speed vortex separator installed in a vertical reservoir-settling tank with a funnel-shaped housing with a spiral guide surface located inside it, connected to the sludge taps, the lattice frame is combined with the plate calm the distributor body of the stream exiting the low-speed vortex separator, in addition, the vertical sump tank contains a clarified water collector and a sludge collector equipped with a sludge washout device outside the process circuit, and a low-speed vortex separator, sump tank, storage reservoir and high-speed vortex separator form a sequential technological chain. 2. Installation according to claim 1, characterized in that the sludge flush device is designed as an envelope for the sludge receiver of the spray conduit with spray holes and an autonomous source of spray liquid. 3. Installation according to claim 1, characterized in that the storage tank is provided with an additional section for purified water in a high-speed vortex separator, and between the sections an overflow of water through a semi-submersible intersection partition is possible.

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