UNIT FOR TREATING FLOWING LIQUID

Abstract

A unit (8) is intended for treating waste water. It includes a well (9) with an inlet conduit connector (21) and with an outlet conduit connector (22) at the outside of the well (9). The unit further includes a connecting conduit (20) inside the well (9). The connecting conduit (20) connects the inlet conduit connector (21) to the outlet conduit connector (22). There is at least one storage tank (13) inside the well (9) for a liquid chemical and a metering pump (18) inside the well (9) for pumping the chemical from the storage tank (13) into the connecting conduit (20). A control device (23) activates the metering pump according to a signal of a sensor (24) which senses a quantity of chemical element in the liquid flowing through the conduit (20).

Claims

1. A unit for treating flowing liquid, the unit comprising: a well an inlet conduit connector and an outlet conduit connector at the outside of the well; a connecting conduit inside the well, said connecting conduit connecting the inlet conduit connector to the outlet conduit connector; at least one storage tank inside the well for at least one liquid chemical; a metering pump inside the well for pumping the at least one chemical from the storage tank into the connecting conduit; and a metering control unit configured to activate the metering pump.

2. A unit according to claim 1, further comprising: a flow sensor for detecting flow in the connecting conduit; a quantity sensor for detecting a quantity of one or more chemical compounds or elements of the liquid in the connecting conduit, wherein a metering pump conduit connects the metering pump to the connecting conduit and the quantity sensor is disposed upstream or downstream or both upstream and downstream of a run-out of the metering pump conduit, and the metering control unit is configured to activate the metering pump dependent on the detected flow and quantity.

3. A unit according to claim 2, wherein the quantity sensor is configured to detect the quantity of the one or more chemical compounds or elements of the liquid in the connection conduit downstream of the run-out of the metering pump conduit and the metering control unit provides a closed-loop control for metering.

4. A unit according to claim 1, further comprising a cover, wherein the well is configured to be arranged in the ground, with an upper end extending to the surface of the ground and closed by the cover.

5. A unit according to claim 1, wherein the storage tank is arranged at a bottom of the well.

6. A unit according to claim 1, wherein an upper side of the storage tank or a platform arranged on the upper side of the storage tank forms a human support floor surface for a person entering the well.

7. A unit according to claim 4, wherein the cover has a fixed part and a movable part, said movable part being pivoted on the fixed part.

8. A unit according to claim 7, further comprising a venting pipe connected to the storage tank and leading to atmosphere, said venting pipe leading through the fixed part of the cover.

9. A unit according to claim 7, wherein a filling pipe opens into the storage tank and ends below the movable part of the cover or above the fixed part of the cover.

10. A unit according to claim 1, wherein a distance between the quantity sensor and the run-out of the metering pump conduit corresponds to at least 5% of a diameter or width dimension of the well.

11. A unit according to claim 1, wherein the connecting conduit inside the well is arranged in a middle third of an overall height of the well and at least 80 cm under a top of the well.

12. A unit according to claim 1, wherein a connecting conduit inside the well is arranged at a distance to the middle of the well and off center

13. A unit according to claim 1, further comprising an external sensor connection for an external sensor comprising a gas phase sensor or liquid phase sensor or both a gas phase sensor and a liquid phase sensor for detecting a quantity of one or more chemical compounds or elements.

14. A unit according to claim 1, further comprising a housing on an inside wall of the well, wherein the metering control unit is arranged next to the connection conduit in the housing on the inside wall of the well.

15. A unit according to claim 1, wherein an electric control of the unit is arranged in a housing on the inside wall of the well.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the drawings:

[0023] FIG. 1 is a simplified representation of a sewage system with two pumping stations and a unit according to the invention arranged in the pipeline between;

[0024] FIG. 2 is a simplified enlarged representation of the unit of FIG. 1; and

[0025] FIG. 3 is a top down view on a unit of another embodiment of the invention without cover.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Referring to the drawings, FIG. 1 shows a part of a sewage system with two pump stations 1 and 2 which are connected by a pipeline. These pump stations 1, 2 are each part of an underground pit 3 with one or more pipes 4 leading waste water to the pit. Inside the pit 3 is a level-controlled waste water pump which in this case is a centrifugal pump 5 for emptying the pit 3 when the level inside the pit has reached a predetermined height. The outlet of the pump 5 of the pump station 1 is connected to an outlet pipe 6 which is connected with an inlet pipe 4 of the next pump station 2. The pit 3 of the pump station 2 has a higher level than the pit 3 of the pump station 1. This part of a sewage system stands for any waste water pipeline leading to a pit or coming from a pit. As mentioned in the introduction it is often a problem of sewage systems that there is hydrogen sulfide in the water which exits as soon as there is a free space over the water as you find in any pit or following gravitational sewer system. Then this toxic hydrogen sulfide gas arises which should be avoided.

[0027] For this purpose a unit 8 for treating flowing waste water is arranged in the pipeline between the pump stations 1 and 2, which pipeline comprises the outlet pipe 6 and the inlet pipe 4. This pipeline has been interrupted and the unit 8 has been inserted.

[0028] The unit 8 comprises a well 9 which has mainly a cylindrical form with a diameter of 1 meter and a height of 2.5 meters. The diameter of the well 9 has to be at least 1 meter but may be bigger. This well 9 is intended for being arranged in the ground so that its upper end has the level of the surface 10 of the ground. The upper end of the well 9 is closed by a cover which comprises a fixed part 11 and a movable part 12. The movable part 12 is pivotably connected with the fixed part 11. So the movable part 12 can be opened by folding from its horizontal position (as can be seen in FIGS. 1 and 2) to a vertical position.

[0029] At the bottom of the well 9 there is arranged a storage tank 13 for a liquid. The surface of this storage tank 13 forms a floor of the interior of the well 9 so that a person entering the well 9 through the opened part 12 can stand on this floor 14. The storage tank 13 is connected to the atmosphere by a vertical venting pipe 15. This venting pipe 15 leads through the fixed part 11 into the atmosphere. Beneath this venting pipe 15 there is a filling pipe 16 which ends in the storage tank 13 and which also leads through the fixed part 11 with a lockable cap at the end. Through this filling pipe 16 the storage tank 13 can be filled with a liquid.

[0030] A transfer tube 17 reaches to the ground of the storage tank 13 and leads to a metering pump 18 which pumps into a conduit 19 which leads to a connecting conduit 20 of a bigger diameter. This connecting conduit 20 crosses the well 9 at a distance from the middle axis.

[0031] This connecting conduit 20 connects the outlet pipe 6 of the pump station 1 with the inlet pipe 4 of the pump station 2. The connecting conduit 20 has two connectors outside the well 9, which is an inlet conduit connector 21 and an outlet conduit connector 22. In this embodiment the connectors are designed as flanges. However, any other suitable connector could be arranged there. The unit 8 is inserted in the sewage system by way of these connectors 21 and 22.

[0032] The metering pump 18 which pumps liquid from the storage tank 13 to the connecting conduit 20 is controlled by a digital control unit 23. This control unit 23 starts and stops the metering pump 18 dependent on the signal received by a sensor 24 in a distance d upstream of the run-out 25 of the conduit 19 from the metering pump 18. There is a further sensor 26 downstream the run-out 25 and a flow meter 27 between the sensor 24 and the run-out 25. The sensors 24 and 26 are liquid phase sensors and they detect inside the connecting conduit 20. There may be further sensors outside the well 9 which may be a gas phase sensor 28 as can be seen in FIG. 1 and/or a liquid phase sensor. There is a connector 29 at the control unit 23 for connecting this sensor 28.

[0033] In the described embodiment according to FIGS. 1 and 2 the sensors 24 and 26 are liquid phase sensors for detecting the quantity of H.sub.2S in the sewage water, the gas phase sensor 28 detects the quantity of H.sub.2S in the air in the pit 3.

[0034] At the beginning of operation of the unit 8 in the sewage system the storage tank 13 is filled with liquid solution of iron salts. During operation the waste water in the pit 3 of the pump station 1 is pumped by the pump 5 through the pipe 6 through the connecting conduit 20 of the well 9 and through the pipe 4 into the pit 3 of the pump station 2. The quantity of H.sub.2S in the waste water entering the connecting conduit 20 is measured by the sensor 24. The flow meter 27 measures the flow velocity. According to this data the quantity of the liquid of this ironsalts in aqueous phase is computed in the control unit 23. This quantity is needed to eliminate the H.sub.2S in the waste water flowing through the conduit 20. Accordingly, the metering pump 18 is activated and the computed quantity is realized by controlling the speed of the pump 18. With the H.sub.2S liquid phase sensor 26 downstream the run-out 25 the quantity of H.sub.2S in the liquid flowing through this conduit 20 is measured. If the dosing of the fluid from the storage tank 13 is correct, there should not be any more H.sub.2S in the water. If the sensor 26 still detects H.sub.2S the remaining quantity is calculated and the control unit 23 will increase the speed of the pump 18 and the quantity of the liquid added in the run-out 25. There is a closed-loop control for regulating the quantity of liquid which means for controlling the switching on and off and the speed of the metering pump 18.

[0035] Depending on the waste water system and the local circumstances there may be connected an additional gas phase sensor in the control unit 23. This sensor 28 may be arranged additionally to sensor 26 or alternatively.

[0036] In FIG. 3 an alternative measurement is shown. This arrangement should be used if the pH value of the liquid running through the connecting conduit 30 is not low. In this case there is a measuring conduit 30 arranged in parallel to the connecting conduit 20 inside the well 9. In this measuring conduit 30 the pH value is measured and if necessary acid is added from an acid storage tank 31 by a dosing pump 32 into the conduit 30. This arrangement makes sure that the measurement of the liquid phase sensor 24 always takes place at a low pH value below 4. In this embodiment the run-out 25 of the conduit 19 is near the downstream end of the connecting conduit 20.

[0037] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

APPENDIX

[0038] 1—pump station [0039] 2—pump station [0040] 3—underground pit [0041] 4—inlet pipe [0042] 5—circulation pump [0043] 6—outlet pipe [0044] 8—unit [0045] 9—well [0046] 10—surface [0047] 11—fixed part of the cover [0048] 12—movable part of the cover [0049] 13—storage tank [0050] 14—floor [0051] 15—venting pipe [0052] 16—filling pipe [0053] 17—transfer tube [0054] 18—metering pump [0055] 19—conduit [0056] 20—connecting conduit [0057] 21—inlet conduit connector [0058] 22—outlet conduit connector [0059] 23—control unit [0060] 24—liquid phase sensor [0061] d—distance between sensor 24 and the run-out 25 [0062] 25—run-out [0063] 26—liquid phase sensor [0064] 27—flow meter [0065] 28—gas phase sensor [0066] 29—connector [0067] 30—measuring conduit [0068] 31—acid storage [0069] 32—dosing pump