WO1999038605A1

WO1999038605A1 - Processing unit

Info

Publication number: WO1999038605A1
Application number: PCT/SE1999/000112
Authority: WO
Inventors: Per-Åke Fagrell
Original assignee: Fagrell Per Aake
Priority date: 1998-01-29
Filing date: 1999-01-28
Publication date: 1999-08-05
Also published as: SE9800261L; SE509816C2; AU2555699A; SE9800261D0; NO20003844L; EP1073510A1; PL342848A1; WO1999038605A9; ID27056A; NO20003844D0; EE200000445A

Abstract

The invention relates to a processing unit (1) for dissolving dry substances in the state of powder, granulate or crushed material in water and mixing and dosing of same comprising a stand (2), an upper container (3) connected to a screw feeder (18) and an evacuating device (20), a conical/cylindrical intermediate part (6) through which more dissolved substances can be supplied from external containers (13) and a lower container (9) for curing, mixing and dosing of the mixture via an outlet (11). The process is controlled via a control unit (28) receiving signals from level and pH sensors and transmits control signals to magnet valves regulating the water supply for optimised pH value and alkalinity in the dosed mixture and to the screw feeder to regulate the amount of dry substance supplied in the upper container.

Description

Processing unit

The present invention relates to a processing unit for dissolving different water soluble dry substances in the state of powder, granulate or crushed material and dosing of the solution, comprising an upper container for adding not dissolved substance and water, a conical/cylindrical intermediate part and a lower container for curing and dosing of the solution.

Acidification of forests, watercourses and lakes is a great problem in the industrial community. The cause is mostly found in the acidic fallout originating from the big processing plants in the world for pulp, paper, chemistry, iron and steel, etc. Before the sources of the pollution in the state of acidic fallout and discharges has been decontaminated or eliminated great measures are taken to counteract the result of the acidification. As to the forests, watercourses and lakes it is preferably made by spreading limestone (calcium carbonate) as powder to raise the pH value.

Production and handling is energy consuming and expensive as is the spreading. Treatment of forests is often carried out from the air or from floating platforms in lakes and watercourses.

The material used is limestone ground to powder, which often has a great deal of impurities of sand and clay not being active in the neutralisation process. To achieve satisfying results a much greater amount of material is used up than would be the case if it was clean and all of it could be used. Using dry substances will also reduce the ground penetration.

Cleaning of sewage is carried out with different methods today. The most common is partly biological processes including adding of chemicals for one thing because of flocking the solid constituents of the sewage. Agents used are generally aluminium sulphate and ferric chloride. Both are substances, which will remain in the settled flocking, which earlier was collected and used as fertiliser in the agriculture. However both chemicals are injurious to the environment and unhealthy for animals and human beings. Today deposition is prescribed but this will create problems in the long run by leaching and gradually affecting the ground water.

Cleaning by creating so-called wet ground areas takes a lot of land and emits nasty smell. Great efforts are also needed to gradually take care of the settled components. There are also methods that collect the sewage in sedimentation basins with intermediate steps of oxygenation in stairs where the water is exposed to the oxygen in the air. Even this method creates smell problems and takes a lot of space.

Consequently it would be advantageous to be able to produce a solution in a rational way that simply could be spread or added in the above mentioned cases of treatment of water and sewage. An earlier filed, later cancelled application, SE 9404207-4, discloses a device according to the introduction, which is preferably designed to dissolve MESA, which is a waste product from the paper industry and that to a great extent consists of calcium carbonate. However the device is impaired by great insufficiencies as to effective dissolving of the dry substance and is completely missing functions to automatically control the adding of dry substance, additives and water to achieve an optimal result regarding the pH value of the active solution and the alkalinity. A lower part of the container designed to cure the solution, by its design contributes to partially sediment the solution before it is dosed out, which decreases the effectiveness. Device for adding other substances is also missing.

Other known devices for producing solutions of different chemicals, preferably calcium carbonates and polymers for flocking in water, operate with mechanical stirring. However the experiences from these devices are not so good due to the dissolving being bad and remaining not dissolved or partly dissolved substances cause break down by coatings appearing on movable parts and in pipes. The efficiency will be low since this remains does not take part in the cleaning process. The devices are not suitable either to operate with unkilled lime that produces strong heat and steam. The object of the present invention is to eliminate the above disadvantages by a device that also can operate with unkilled lime without problems for the environment and without causing stowing of feeding attachments by that steam from the process is spread to feeding attachments and lime containers. The advantage of working with unkilled lime is amongst other things that the process becomes stressed so that a maximum pH value in the completed solution is achieved. Furthermore the device would be designed so that sedimentation is effectively prevented and that the concentration of the solution easily can be controlled. Another object is to allow adding of other substances, for instance flocking agents to achieve that for instance solid impurities in sewage are flocked and settled to be easier to take care of.

Yet another object is to make the device safe from the working environment point of view both regarding spillage and removing of injurious gases. These objects are achieved with a device in the shape of a processing unit having the characteristics stated in claim 1 and the

A preferred embodiment of the present invention will now be described with reference to the accompanied drawings, in which:

Fig. 1 shows a view of the exterior of a processing unit;

Fig. 2 shows an interior view of a processing unit;

Fig. 3 shows a block diagram of the function of a processing unit;

Fig. 4 shows a level sensor in the shape of a cone; Fig. 5 shows a level sensor system in the shape of a photo-electric device;

Fig. 6 shows a level sensor system in the shape of electrical load sensors in the legs of the stand.

Fig. 1 shows a processing unit 1 mounted in a stand 2 with three legs. The unit has three major parts; an upper container 3 with a first cover 4 placed on a jointing ring 5 on a intermediate part 6 with a conical upper part 7 and a cylindrical lower part 8 and a lower container 9 with a second cover 10 and an outlet pipe 11. Between the wall of the upper container and the legs of the stand are vibration-damping means 12 mounted. On the side of the upper container is an outer container 13 mounted. In the disclosed embodiment the legs are provided with wheels 15.

Fig. 2 shows an inside view of the processing unit 1 where the location of the different inner parts is visible. In cover 4 of the upper container is a vertical pipe 16 mounted for feeding dry substance and air to the interior of the device. Horizontally in an opening 17 in the wall of the pipe, above the cover 4, is an outlet from a screw feeder 18 connected. In the cover, at the side of the first pipe is a second pipe attached, which is connected to a dust extractor 20 with a dust catcher 21. A disc, perforated all over the surface or a net 22 lies on supporting shoulders 23 attached to the wall of the upper container at a distance (typically 20 - 25 cm) above the lower edge of the container. Under the disc, on a frame 24, at least one spray nozzle 25 is mounted at such a distance from the underside of the disc and with such a scattering angle that every point on the underside of the perforated disc will be hit by water jets. The nozzle is connected to the water system 26 via a first magnet valve 27. A control unit 28 controls the magnet valve with signals from a level sensor 29 in the lower container. Inside the upper container, above the disc 22 a coiled pipe 30 provided with radial, inwardly directed small openings is arranged for distributing a curtain of small water drops over the small particles dusting, in the light upwards directed air stream caused by the dust extractor, from the dry substance supplied to the upper container by the screw feeder through the pipe 16 in the cover. The dust particles will thereby form lumps and fall back on the mass of dry substance and be prevented from being sucked out through the dust extractor. Hereby nothing of the dry substance intended for taking part of the process will be wasted. The pipe sling can be positioned in at least two different positions or by continuous vertical displacement in a covered slot in the wall of the container to obtain optimal effect of the adding of water.

The cylindrical part of the container 8 on the intermediate part 6 extends via a sealing joint 31 into the lower container 9. In the wall of the conic intermediate part a level control in the shape of a spillway 32 as well as a filler tube 33 are mounted. More external containers can be mounted for supplying more additives. More external containers can be attached for feeding in of more additives. Above the outlet pipe 11 a level sensor 29 is applied whose signals control the water supply to the spray nozzle 25 via the control unit 28.

In the lower container 9, whose lower part has the shape of a truncated cone, a nozzle 35 is attached via a pipe 34 above the plane surface 36. The pipe and the nozzle are connected to the water system via a second magnet valve 37. The control unit 28 who receives signals from for instance the pH sensors in a sewage basin (not shown) controls the valve in which the mass will be cleaned. The purpose of he nozzle 35 is to agitate the solution in the lower container from the plane bottom surface 35 towards the conical walls to effectively mix the two components of the solution and prevent the solution from sedimentation as well as to control the concentration of calcium hydroxide in the solution that is supplied to the sewage basin. This leads to optimised cleaning and flocking independent of the composition of the sewage mass, (for instance fat content) and pH value. To control the supply of an optimised amount of dry substance for the dissolving process different solutions are available. In one embodiment a cone 40 has been applied with its small opening around the first pipe 16 in the cover 4 in the upper container, which is shown in fig. 4. The cone has its larger opening 41 turned downwards and it ends at such a height above the perforated disc 22 that an optimised supply of dry substance is achieved.

In another embodiment shown in fig 5, a photoelectric device is attached in the wall of the upper container at a suitable height for optimal amount of dry substance. On one side of the container a light source 50 is applied in a first protective tube 51 and diametrically opposite, on the same height, a photoelectric cell 52 is applied in a second protective tube 53. The signal from the photoelectric cell 52 controls the screw feeder 18 via the control unit 28.

In a further embodiment shown in fig. 6 sensors 60 in the legs of the stand 2 solve the problem. Their signals control the screw feeder to keep an optimised total weight of the processing unit for each type of process. When treating unkilled lime in the processing unit a lot of heat and vapour is produced that pass the dry substance and easily creates a solid layer on the surface of the dry substance and hamper the process. To break this layer a vibrator 38 is mounted on the outside of the wall of the upper container, on a level with the dry substance level. A suitable vibration frequency is 100 Hz, i. e. the frequency that can be obtained from the regular power net. The amplitude is adjustable and the vibration absorbing means 12 attached between the wall of the upper container and the legs of the stand prevents undesired vibrations to be transferred to other parts of the processing unit.

The function of the processing unit is obvious from the block diagram in fig. 3. The screw feeder 18 transports dry substance to the upper container 3 where it is collected on the perforated disc 22. The amount of dry substance is kept constant by sensing the height of the dry substance above the disc by level sensors and via the control unit 28 control the rotation of the screw feeder 18. The magnet valve 27 via the control unit 28 controls the supply of water. The dry substance is evenly dissolved above the perforated disc and the solution flows down through the intermediate part 5 and flows out through the opening of the cylindrical part 8, near the bottom of the lower container 13. Supplying water to the lower container mixes the components. The amount of water is controlled by a magnet valve 35 controlled by the control unit 28 with signals from pH-sensors in for instance a sewage basin.

Claims

1. Processing unit (1 ) for dissolving different water soluble dry substances in the state of powder, granulate or crushed material and dosing of the solution, comprising an upper container (3) for adding not dissolved substance and water, a conical/cylindrical intermediate part (6) and a lower container (9) for curing and dosing of the solution, c h a r a c t e r i s e d by that the processing unit is mounted in a stand (2), that the upper container has a first cover (4) and a first pipe (16) arranged centrally in the cover for supplying dry substance and air, to which a feeder device (18), preferably a screw feeder is horisontally connected and a second pipe (19) connected to an evacuating unit (20) wit a dust catcher (21), that the upper container has a perforated disc (22) placed on supporting abutments (23) under which at least one spray nozzle (25) is arranged to sprinkle water on the disc from underneath and that the amount of water is controlled by a first magnet valve (27) controlled by a control unit (28) by signals from a level sensor (29) in the lower container, that a coiled pipe (30) with a lot of radial inwardly directed fine openings is arranged along the inner wall of the container and vertically adjustable in at least two positions on the wall of the upper container and that the upper container is detachable placed on a jointing ring (5) on the conical part (7) of the intermediate part (6) and supported by the legs of the stand via vibration absorbing means (12), that the conical part of the wall of the intermediate part has an inlet pipe (33) for supplying other substances from at least one external container (13) attached beside the upper container in which additional solution of for instance biological polymer is prepared and that the cylindrical part of the intermediate part (8) via a sealing joint (31) in a second cover (10) discharges in the lower container (9), that above a plane bottom (36) a nozzle (35) is arranged to bring the components of dissolved substance from the upper container and additive from the external container flowing through the opening of the cylindrical part of the intermediate part in motion by means of power water for mixing the components and preventing sedimentation on the bottom and that the supplied amount of water is controlled by a second magnet valve (37) controlled by the control unit (28), which receives a signal representing the pH value in for instance the sewage to be cleaned by the mixture discharged from the lower container via an outlet pipe (11).

Processing unit according to claim ^characterised in that a level limiting device in the shape of a cone (40) for the dry substance is mounted in the cover of the upper container with its smaller opening surrounding the mouth of the centrally arranged pipe (16) and its wider opening (41) directed downwards and located at such a height above the perforated bottom (22) that an optimised amount of dry substance is supplied.

3. Processing unit according to claim ^characterised in that a level limiting device in the shape of a photoelectric device is arranged in the wall of the upper container at such a height above the perforated bottom (22) that an optimised amount of dry substance is supplied and which device comprises a light source (51) mounted in a first protective tube (50) and diametrically opposite a photo cell (53) in a second protective cover (52) and that the output signal from the photo cell controls the screw feeder via the control unit (28).

4. Processing unit according to claim 1 , c h a r a c t e r i s e d in that the processing unit has a level limiting device in the shape of electrical load sensors (60) in the legs of the stand (2) whose signals controls the screw feeder via the control unit (28).

5. Processing unit according to claim ^characterised in that on the outside of the wall of the upper container a vibrator (38) is mounted.