A METHOD OF GREASING A DECANTER CENTRIFUGE

Abstract

In a method of greasing a decanter centrifuge, each beating of the decanter centrifuge is located in a bearing housing and at least one bearing housing has a grease flow meter. The grease flow meter is connected to a control unit. The method includes generating a greasing operation when the operating time of the decanter centrifuge is equal to or exceeds a specific time interval between greasing operations. The greasing operation includes generating a start signal in the control unit, measuring an amount of grease injected into the bearing housing by using the flow meter, and generating a stop signal in the control unit when the amount of grease injected into the bearing housing is equal to or exceeds a specific amount of grease to be injected at each greasing operation.

Claims

1. A method of greasing a decanter centrifuge, the decanter centrifuge comprising a rotating bowl suspended between bearings, each bearing being located in a bearing housing, at least one bearing housing having a grease flow meter, the grease flow meter being connected to a control unit, the control unit defining a specific amount of grease to be injected at each greasing operation and a specific time interval between greasing operations, the method comprising the steps of: operating the decanter centrifuge by rotating the bowl while measuring an operating time since the last greasing operation in the control unit; and generating a greasing operation when the operating time of the decanter centrifuge is equal to or exceeds the specific time interval between greasing operations, the greasing operation including: generating a start signal in the control unit; measuring an amount of grease injected into the bearing housing by using the flow meter; and generating a stop signal in the control unit when the amount of grease injected into the bearing housing is equal to or exceeds the specific amount of grease to be injected at each greasing operation.

2. The method according to claim 1, wherein the bearing housing comprises a temperature sensor and the step of operating the decanter centrifuge includes measuring a bearing housing temperature by using the temperature sensor.

3. The method according to claim 2, wherein the method comprises the step of setting the specific time interval between greasing operations to less or equal to the operating time since the last greasing operation when between greasing operations the bearing housing temperature increases beyond a first specific temperature, the first temperature being indicative for an under-greasing of the bearing housing.

4. The method according to claim 3, wherein the specific amount of grease to be injected at each greasing operation is increased when between greasing operations the bearing housing temperature increases beyond the first specific temperature.

5. The method according to claim 2, wherein the method comprises the step of generating a stop signal and setting the specific amount of grease to be injected at each greasing operation to less or equal to the amount of grease injected into the bearing housing when during the greasing operation or immediately thereafter the bearing housing temperature increases beyond a second specific temperature, the second specific temperature being indicative for an over-greasing of the bearing housing.

6. The method according to claim 5, wherein the method comprises the step of increasing the specific time interval between greasing operations when during the greasing operation or immediately thereafter the bearing housing temperature increases beyond the second specific temperature.

7. The method according to claim 1, wherein the decanter centrifuge comprises a grease pump connected to the bearing housing, whereby the start signal causes the pump to start and the stop signal causes the pump to stop.

8. The method according to claim 1, wherein the bearing housing comprises a grease inlet and the decanter centrifuge comprising a human-machine interface for communicating the start signal and the stop signal to a user.

9. The method according to claim 1, wherein the bowl is rotating during the greasing operation.

10. The method according to claim 1, wherein the specific amount of grease to be injected at each greasing operation and the specific time interval between greasing operations are based on the size and the operational pattern of the decanter centrifuge.

11. The method according to claim 1, wherein each of the bearing housings comprises a separate flow meter connected to the control unit.

12. A computer program embodied on a non-transitory computer-readable medium, and comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of claim 1.

13. (canceled)

14. A control unit for controlling a greasing operation of a decanter centrifuge, the decanter centrifuge comprising a rotating bowl suspended between bearings, each bearing being located in a bearing housing, at least one bearing housing having a grease flow meter, the grease flow meter being connected to the control unit, the control unit defining a specific amount of grease to be injected at each greasing operation and a specific time interval between greasing operations, the control unit being adapted for measuring an operating time of the decanter centrifuge since the last greasing operation and generating a greasing operation when the operating time of the decanter centrifuge is equal to or exceeds the specific time interval between greasing operations, the greasing operation comprising: generating a start signal in the control unit; measuring an amount of grease injected into the bearing housing by using the flow meter; and generating a stop signal in the control unit when the amount of grease injected into the bearing housing is equal to or exceeds the specific amount of grease to be injected at each greasing operation.

15. A decanter centrifuge comprising the control unit according to claim 14.

16. The method according to claim 3, wherein the method comprises the step of generating a stop signal and setting the specific amount of grease to be injected at each greasing operation to less or equal to the amount of grease injected into the bearing housing when during the greasing operation or immediately thereafter the bearing housing temperature increases beyond a second specific temperature, the second specific temperature being indicative for an over-greasing of the bearing housing.

17. The method according to claim 4, wherein the method comprises the step of generating a stop signal and setting the specific amount of grease to be injected at each greasing operation to less or equal to the amount of grease injected into the bearing housing when during the greasing operation or immediately thereafter the bearing housing temperature increases beyond a second specific temperature, the second specific temperature being indicative for an over-greasing of the bearing housing.

18. The method according to claim 2, wherein the decanter centrifuge comprises a grease pump connected to the bearing housing, whereby the start signal causes the pump to start and the stop signal causes the pump to stop.

19. The method according to claim 3, wherein the decanter centrifuge comprises a grease pump connected to the bearing housing, whereby the start signal causes the pump to start and the stop signal causes the pump to stop.

20. The method according to claim 4, wherein the decanter centrifuge comprises a grease pump connected to the bearing housing, whereby the start signal causes the pump to start and the stop signal causes the pump to stop.

21. The method according to claim 5, wherein the decanter centrifuge comprises a grease pump connected to the bearing housing, whereby the start signal causes the pump to start and the stop signal causes the pump to stop.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 is a side view of a decanter centrifuge of the present invention.

[0056] FIG. 2 is a perspective view of an automatic greasing system of the present invention.

[0057] FIG. 3 is a perspective view of a manual greasing system of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0058] FIG. 1 is a side view of a decanter centrifuge 10 according to the present invention. The decanter centrifuge 10 comprises a casing 12. The casing 12 protects the user from a rotating bowl 14 below the casing 12. The rotating bowl 14 extending between a large hub 14a and a small hub 14b. The bowl 14 is rotationally supported by two opposite bearings (not visible) inside respective bearing housings 16 16, one at the large hub 14a and one at the small hub 14b. A screw conveyor 18 is located inside the bowl 14. The starting material is injected into the bowl 14 via a feed inlet channel 20 extending inside the conveyor screw 18, as shown by the filled arrows. The starting material is separated into a light phase (liquids) exiting at the large end hub 14a as shown by the white arrow and a heavy phase (solids) exiting at the small end hub 14b as shown by the dotted arrow.

[0059] The bowl 14 is driven by a motor 22 via a belt 24. By the rotation of the bowl 14, the light phase and the heavy phase are separated into layers inside the bowl. The screw conveyor 18 is driven at a differential speed relative to the bowl 14 via a gearbox 26. The differential speed between the bowl 14 and the screw 18 causes the screw conveyor 18 to convey the heavy phase toward the small end hub 14b. The differential speed is set by a back-drive motor 28 which is coupled to the gearbox 26.

[0060] The back-drive motor 28, gearbox 26 and bearing 16 are held up by a first frame 30 whereas the main motor 22, the belt 24 and the bearing 16 are held by a second frame 30.

[0061] FIG. 2 is a perspective view of an automatic greasing system 32 according to the present invention. The bowl 14 is rotationally supported by two opposite bearings 34 34 inside a respective hearing housing 16 16. The bearings 34 34 can be ball bearings, roller bearings or the like. The temperature inside each of the bearing housings 34 34 is measured by a respective temperature sensor 36 36. Each bearing housing 16 16 is lubricated by a respective grease tube 38 38

[0062] The grease is stored in a tank 40. The tank 40 is connected to each of the grease tubes 38 38 via a respective grease pump 42 42 and grease flow meter 44 44. The grease flow meter 44 44 is in the present case a positive displacement meter. The temperature sensors 36 36, the pumps 42 42 and the grease flow meters 44 44 are connected to a control unit 46, such as a computer.

[0063] The control unit 46 stores values for each bearing 34 34 for defining a specific amount of grease to be injected at each greasing operation and a specific time interval between greasing operations. The operating time since the last greasing operation of each bearing 34 34 of the decanter centrifuge 10 is measured. When the operating time since the last greasing operation of one of the bearings 34 34 of the decanter centrifuge 10 is equal to or exceeds the specific time interval between greasing operations for that particular bearing of the bearings 34 34, a greasing operation is started for that particular bearing. A start signal for the particular bearing of the bearings 34 34 is generated in the control unit 46. The particular pump of the pumps 42 42 connected to the particular grease tube of the grease tubes 38 38 is started and the amount of grease injected into the particular bearing housing is measured by using the relevant flow meter of the flow meters 44 44.

[0064] When the amount of grease injected into the particular bearing housing is equal to or exceeds the specific amount of grease to be injected at each greasing operation for the particular bearing of the bearings 34 34, a stop signal is generated for the particular bearing of the bearings 34 34 and the particular pump of the pumps 42 42 is stopped.

[0065] The temperature in each of the bearing housings 16 16 is constantly measured. In case the temperature is increasing in a particular bearing housing of the bearing housings 16 16 during or immediately after a greasing operation, it is an indication for an over-greasing of the particular bearing of the bearings 34 34. If that is the case, the greasing operation is stopped, the amount of grease injected into the particular bearing housing of the bearing housings 16 16 is reduced and, optionally, the specific time interval between greasing operations for that particular bearing of the bearings 34 34 is increased.

[0066] However, in case the temperature is increasing in a particular bearing housing of the bearing housings 16 16 between greasing operations, it is an indication for an under-greasing. Then the greasing operation is started, the specific time interval between greasing operations for that particular bearing of the bearings 34 34 is decreased and, optionally, the amount of grease injected into the particular bearing housing is increased.

[0067] FIG. 3 is a perspective view of a manual greasing system 32 of the present invention. The manual greasing system 32 is similar to the automatic greasing system above, except that the grease pumps have been replaced by a respective grease flow inlet 48 48 for each of the bearings 34 34. The start signal and the stop signal for each bearing 34 34 is determined in the same way as in the automatic greasing system above, however, instead of causing the respective grease pumps to start and stop, the start signal and the stop signal causes a respective visual indication 50 50 for each bearing 34 34 to indicate that a greasing operation should start or stop, respectively. The visual indications 50 50 act as human-machine interface, however, alternative human-machine interfaces are possible such as sound indications or various kinds of messages using telecommunication networks or computer networks.

[0068] The visual indication 50 50 guides the user to start a manual greasing operation by applying a manually controlled grease pump to the particular inlet 48 48 which visual indication 50 50 indicated that a greasing operation should start. The user applies grease until the particular visual indication 50 50 indicates that the greasing operation should stop. Then, the user stops the greasing operation and awaits the next indication that a greasing operation should start. The grease flow into each bearing housing 16 16 and the temperature of each bearing housing 16 16 is measured in the same way as in the automatic greasing system above. The specific amount of grease to be injected at each greasing operation and the specific time interval between greasing operations are also determined by the control unit/computer 46 in the same way as in the automatic greasing system above.

[0069] The systems and methods according to the present invention mainly concerns the main bearings of the decanter centrifuge, i.e. the bearings which rotationally support the bowl, however, the auxiliary bearings which support e.g. the screw, can also use the systems and methods.