WO2002050381A1

WO2002050381A1 - Vacuum line clearance system

Info

Publication number: WO2002050381A1
Application number: PCT/AU2001/001670
Authority: WO
Inventors: John Brendan Berry
Original assignee: John Brendan Berry
Priority date: 2000-12-21
Filing date: 2001-12-21
Publication date: 2002-06-27
Also published as: AUPR222900A0

Abstract

A vacuum sewerage system control where the vacuum sewerage system comprises a central collection zone and a set of at least one intermediate collection zones where each intermediate collection zone is connected to a set of sewage sources, each intermediate zone connected to a vacuum source through a delivery line to maintain the at least one delivery line in a state of vacuum, the inlet for each delivery line from the respective intermediate collection zone being controlled by a valve which is adapted to open selectively to deliver the contents of the intermediate collection zone into the delivery line, a monitor means for sensing an adverse condition in the at least one delivery line, the adverse condition being a condition indicative of the presence of a low vacuum state in the at least one delivery line for an undesirable length of time, the monitor means to provide an activation signal to a control means on the sensing of an adverse condition, the control means adapted to adapted control access between the at least one delivery line and the vacuum source, whereby the control means will isolate the at least one delivery line from the source of vacuum for a period of time in the event of an adverse condition and provide access between the at least one delivery line and the source of vacuum on the expiration of the period of time. A method of controlling a vacuum sewerage system is also claimed.

Description

Vacuum line clearance system

Field of the Invention

This invention relates to a line clearance system and in particular has application to a vacuum sewerage system.

Background Art

Vacuum transport provides an alternative to gravity as a means of installing sewerage systems. Vacuum transport can have particular advantages in flat areas and areas subject to a high water table.

A vacuum sewerage system generally comprises a centralised collection zone which is connected to a number of outlying interface pits or intermediate collection zones where each of the interface pits are connected to the individual houses or buildings being serviced by the sewerage system. The interface pits are connected with the central collection zone by a delivery pipe and the entry of effluent from the interface pits into the delivery pipes is controlled through an interface valve which is in turn controlled by a sensor associated with the pit which will open the interface valve on the sensor noting that the pit reaches a predetermined discharge level. The delivery lines are subjected to a vacuum whereby on the opening of the interface valve the effluent is drawn into the delivery line. In addition to the effluent, air is drawn into the delivery line with the effluent and it is the intermixing of the air with the effluent that causes the effluent to be transported along the delivery line to the collection zone. In this regard it is common practice to provide a delivery line with a series of high and low zones whereby with a nil flow through the delivery line the effluent will collect in the low zones. This serves to reconstitute the intermixing of air and effluent on the reopening of the interface valve as the effluent is caused to move along the delivery line on the re-opening of the interface valve.

The effectiveness of such a vacuum sewerage system is dependent upon maintenance of an adequate vacuum condition in the delivery lines. In the event that an interface valve is prevented from closing by the presence of an object in the valve the continued opening of the valve will lead to the introduction of air into the delivery line and the loss of vacuum which can extend throughout the whole system. When such a condition occurs it is usual practice that the faulty valve has to be identified and the valve to be cleared has to be cleared manually. In large reticulation systems this can be extremely time consuming and labour intensive in that it requires the malfunctioning valve to be identified visually and once identified the valve must be accessed and the blockage cleared.

Disclosure of the Invention

Accordingly the invention resides in vacuum sewerage system control wherein said vacuum sewerage system comprises a central collection zone and a set of at least one intermediate collection zone where each intermediate collection zone is connected to a set of sewage sources, each intermediate zone connected to a vacuum source through a delivery line to maintain the at least one delivery line in a state of vacuum, the inlet for each delivery line from the respective intermediate collection zone being controlled by a valve which is adapted to open selectively to deliver the contents of the intermediate collection zone into the delivery line, a monitor means for sensing an adverse condition in the at least one delivery line, said adverse condition being a condition indicative of the presence of a low vacuum state in said at least one delivery line for an undesirable length of time, said monitor means to provide an activation signal to a control means on the sensing of an adverse condition, the control means adapted to adapted control access between the at least one delivery line and the vacuum source, whereby the control means will isolate the at least one delivery line from the source of vacuum for a period of time in the event of an adverse condition and provide access between the at least one delivery line and the source of vacuum on the expiration of the period of time.

According to a preferred feature of the invention the vacuum source is connected to the at least one delivery line through the central collection zone. According to a preferred feature of the invention a plurality of delivery lines are controlled by the control means. According to a preferred feature of the invention all of the delivery lines are connected to a common vacuum source.

According to a preferred feature of the invention the vacuum source comprises at least one vacuum pump. According to a preferred feature of the invention the vacuum source comprises at least one vacuum reservoir and at least one vacuum pump. According to a preferred feature of the invention at least one of the at least vacuum pumps maintains the vacuum reservoir in a state of vacuum. According to a preferred feature of the invention the control means controls operation of at least one of the at least one vacuum pumps to control access between the at least one delivery line and the vacuum source. According to a preferred feature of the invention wherein the control means controls access between the at least one delivery line and at least one of the at least one vacuum reservoirs. According to a preferred feature of the invention the control means controls access between the at least one delivery line and at least one of the at least vacuum reservoirs and between the at least one delivery line and at least one of the at least one vacuum pump, whereby the at least one delivery line is caused to access both the vacuum reservoir and the vacuum pump on expiration of said period of time.

According to a preferred feature of the invention the vacuum source comprises at least one vacuum reservoir which is maintained in a state of vacuum.

According to a preferred feature of the invention the control means controls a valve for providing access between the at least one delivery line and the vacuum source.

According to a preferred feature of the invention the control is adapted to prevent the reactivation of the control means in the event of a prescribed number of sequential adverse conditions having been sensed.

According to a preferred feature of the invention the monitoring means monitors the period of continuous operation of the vacuum pump in sensing the presence of said adverse condition. According to a preferred feature of the invention the monitoring means monitors the state of vacuum in the at least one delivery line in sensing the presence of said adverse condition.

According to a preferred feature of the invention a plurality of delivery lines are controlled by the vacuum sewerage system control and said control means is adapted to separately control access between each delivery line and the vacuum source. According to a preferred feature of the invention each delivery line is provided with a valve which controls access between the respective delivery line and the vacuum source and said valves are controlled by the control means. According to a preferred feature of the invention on an adverse condition being sensed the control means is adapted to sequentially control access between each delivery line and the vacuum source to locate the delivery line causing the adverse condition.

Accordingly the invention also resides in a method of controlling a vacuum sewerage system wherein the vacuum storage system comprises at least one intermediate collection zones where each intermediate collection zone is connected to a set of sewage sources, each intermediate zone connected to a vacuum source through a delivery line to maintain the at least one delivery line in a state of vacuum, the inlet for each delivery line from the respective intermediate collection zone being controlled by a valve which is adapted to open selectively to deliver the contents of the intermediate collection zone into the delivery line said method comprising monitoring a condition indicative of the state of the vacuum in the at least one delivery line to sense the presence of an adverse condition, said adverse condition being a condition indicative of the presence of a low vacuum state in said at least one delivery line for an undesirable length of time, activating a control means on sensing an adverse condition to isolate the vacuum source from the at least one delivery line for a period of time and to provide access between the at least one delivery line and the vacuum source on expiration of that period of time. According to a preferred feature of the invention the control means controls a valve to control access between the at least one delivery line and the vacuum source.

According to a preferred feature of the invention the control means controls operation of the vacuum source to control access between the at least one delivery line and the vacuum source. According to a preferred feature of the invention the vacuum source comprises at least one vacuum pump.

According to a preferred feature of the invention the control means is not activated in the event of a prescribed number of sequential adverse conditions being sensed.

According to a preferred feature of the invention the increase in vacuum in the at least one delivery line on reactivation of the vacuum generator is rapid.

According to a preferred feature of the invention the sewerage system comprises a plurality of delivery lines and the control means sequentially controls access between each delivery line and the vacuum source on an adverse condition being sensed to locate the delivery line which is the cause of the adverse condition and on location of the delivery line which is the source of the adverse condition sequentially controls access between the delivery line and the vacuum source until an adverse condition is absent or until a prescribed number of sequential adverse conditions has been sensed.

The invention will be more fully understood in the light of the following description of several specific embodiments.

Brief Description of the Drawings

The description is made with reference to the accompanying drawings of which:

Figure 1 is a logic diagram illustrating the operation of a vacuum sewerage system control according to the first embodiment; and Figure 2 is a logic diagram illustrating the operation of a vacuum sewerage system control according to the second embodiment

Detailed Description of Specific Embodiments

Each of the embodiments relate to a vacuum sewerage system control and a method of controlling a vacuum sewerage system which facilitates clearance of blockages that can occur in the valves controlling the entry of effluent into the system.

Vacuum sewerage systems utilise a number of intermediate collection zones which each comprise an interface pit which services a number of sewerage delivery pipes from a number of homes or buildings in the vicinity of the pit and where the sewage enters the lower part of the pit under the influence of gravity. Each pit is connected to a central collection tank through a delivery line and entry into the delivery line is controlled through a vacuum interface valve provided at the interface pit. The operation of the vacuum interface valve is controlled by a sensor. Once the volume of effluent in the pit reaches a predetermined discharge level as sensed by the sensor the interface valve is activated as a result of a signal from the sensor and will remain open for a period of time (approximately 5 seconds) during which time sewage is drawn into the delivery line and the pit is substantially emptied. In addition the interface valve is adapted such that on the opening of the interface valve, a volume of air is also drawn into the delivery line in a manner which causes the air to intimately to mix with the sewage to form a fine suspension of air bubbles in the effluent in the delivery line. The resultant effect of the introduction of the air is that the consequent mixture is carried through the delivery line at a velocity of the order of five to six metres per second. The delivery line is generally laid in a series of high and low points such that the profile of the line is likened to a saw tooth shape. Therefore when the interface is closed and there is substantially no flow through the delivery line the mixture of air and effluent separates and the sewage becomes resident in the lower points of the line to form a series of plugs. On the valve reopening the passage of the air down the vacuum transport line regenerates the mixture of air and effluent to facilitate the transportation of the effluent along the line. Occasionally a vacuum interface valve will become jammed and will be unable to close due to the presence of objects being caught in the valve. Such objects can comprise remnant debris resulting from the fabrication of the line and buildings associated with the line. In addition during service items of household rubbish such as toys, sanitary napkins, syringes, food waste and the like may also enter the interface pit which may cause the jamming of the valve. The jamming open of the valve will cause the delivery line to lose vacuum and result in an inadequate operation of the system if not a failure of the system. This low vacuum condition results in a maintenance crew being required to attend the site and to attempt to locate the faulty valve and rectify the matter. This event can occur at any time and it can be particularly difficult to locate the jammed valve.

Each of the embodiments comprises a control which is to be associated with the system and which monitors the state of the vacuum in the delivery line. It is usual that the vacuum for the delivery line is provided by a vacuum pump which is caused to be activated, on the state of vacuum having fallen below a predetermined level and to be switched off, on the vacuum having attained a particular maximum level. When a vacuum system is at peak operation it can be usual for the vacuum pump to be inoperable for an extensive period of time.

The control system according the first embodiment monitors the operation of the vacuum pump such that it will sense when the vacuum pump has been active for a period of time which is unexpectedly long and which is representative of a situation in which an interface valve has become jammed. In such an event the control system will then deactivate the system by deactivating the vacuum pump. Therefore if there is a jammed interface valve the system will lose vacuum. The control system will then cause the system to remain inactive for a period of time which statistically will correspond to a period of time of sufficient length to allow for sufficient effluent to enter the pit in which the faulty valve is resident in order to cover the inlet of the valve. On expiration of that period of time the vacuum pump is reactivated to create a vacuum in the vacuum line. The reintroduction of vacuum into the vacuum line will then cause effluent to flow from the interface pit into the jammed valve. It is anticipated and experience has shown is most often the case that as a result of the forces exerted by the fluids when passing through the valve the item blocking the interface valve will be dislodged.

The control system according to the first embodiments is further capable of monitoring the state of vacuum in the delivery lines such that in the event of an attempt to re establish a vacuum in a delivery line and the vacuum in the line does not rise to an optimum level within the required time the system will again be deactivated to be reactivated after the elapse of a further period of time of sufficient length to statistically enable effluent to enter the delinquent pit in order to cover the inlet of a faulty valve. On expiration of that period of time the vacuum pump would again be activated to create a vacuum condition in the delivery line to cause effluent to be drawn through the faulty valve. This process can be repeated for a number of times. If on the completion of the activation of the vacuum pump for a predetermined number of times the system is shut down and an alarm is activated whereby a warning is given to enable a maintenance personnel to rectify the problem.

As a result of trials of an example of the first embodiment it has been found that in almost 60% of the blockages occurring in the system can be rectified using the embodiment.

According to a second embodiment of the invention the source of vacuum which is applied to the delivery line on reactivation of the system has a greater capacity from that which is normally available to the system. In vacuum sewerage systems it is usual to have a pair of vacuum pumps whereby one pump will act as the main pump and the other pump will act as a standby pump such that in the event of failure of the main pump the standby pump can be activated. In the case of the embodiment both the main pump and the standby pump would be activated simultaneously or one shortly after the other in order that the rate of attainment of vacuum in the delivery line is maximised when the system is deactivated. This rapid attainment of vacuum will generate a high velocity flow of effluent to dislodge the blockage from the jammed valve. Figure 1 is a logic diagram of the sequence of operation of an example of a system according to the first or second embodiment in the event of a fault being detected. As shown the evidence of a fault occurring will be when the vacuum pump has been operating for a first period of 2 to 45 minutes. In such an event the vacuum pump or pumps associated with the delivery lines are shut down for a second period which can be for a second period of between 5 to 60 minutes. The magnitude of the second period is of sufficient length to enable the pit to fill to a level at which the inlet to the vacuum valve is covered and this will vary depending upon the capacity of the system with which the pits are associated, the nature of the facility being serviced (ie domestic or commercial), the time of day and possibly the day of the week. On the expiration of that second period the pump or pumps are reactivated and period for which they are active in order to establish an adequate level of vacuum is monitored. If the period of operation of the pump or pumps is excessive (ie corresponding to the first period - 2 to 45 minutes) for the system, the pump or pumps are again deactivated for the second period of time. This action is repeated 3 times. If after 3 cycles being applied the fault is still evident, an alarm is activated to enable the fault to be attended to by suitable personnel. If after the reactivation of the pump or pumps, no fault becomes evident, the system is able to operate normally.

According to a third embodiment of the invention the vacuum source comprises at least in part an accumulator which comprises a reservoir which is subjected to a vacuum condition whereby the accumulator is caused to communicate with the delivery lines instead of or in association with the vacuum pump on reactivation of the system. The capacity of the accumulator is sufficiently large to result in a relatively rapid attainment of vacuum in the delivery line or lines on reactivation of the system.

According to a fourth embodiment the sewerage system comprise a number of delivery lines which are each connected into a central collection zone and which can use a number of vacuum pumps to create the vacuum condition in the delivery lines. Each delivery line is connected to the central collection zone through a motorised valve in order that each line can be independently shut off from the central collection zone to isolate the delivery line from the vacuum source.

Figure 2 is a logic diagram of the sequence of operation of an example of a system according to the fourth embodiment. In the event a fault is detected as a result of the vacuum pumps operating for a first period of time (from 2 to 45 minutes) the control system is activated to close one motorised valve (N).

A If on closure of the valve N the vacuum pumps continue to operate this indicates that the fault does not lie with the delivery line associated with valve N. As a result the valve N is opened and the next motorised valve in the sequence N+1 is closed. If after the sequence has been completed for all valves, the vacuum pumps continue to operate this is an indication that there is a general failure of the sewerage system and an appropriate alarm is raised.

B If on closure of the valve N the vacuum pumps cease to operate due to the creation of an adequate vacuum this is an indication that there is a fault in the delivery line associated with Valve N. On the occurrence of such an event the valve N is opened and the period before the vacuum pumps reactivate is monitored.

(a) If the pumps are not reactivated within a second period (1 to 15 minutes) this is taken as indicating that the fault has ceased to exist and the sewerage system reverts to its normal operation.

(b) If the period is less than a second period (1 to 15 minutes) this is indicative that the fault still exists and the valve N is closed for a third period of time (5 to 60 minutes). The magnitude of the third period is of sufficient length to enable the pit to fill to a level at which the inlet to the vacuum valve is covered and this will vary depending upon the capacity of the system with which the pits are associated, the nature of the facility being serviced (ie domestic or commercial), the time of day and possibly the day of the week.

(c) On completion of the third period of time the valve N is reopened and the operation of the vacuum pumps is monitored. If the period is less than a second period (1 to 15 minutes) this is indicative that the fault still exists and the valve N is closed again. This sequence is repeated up to 3 times and if the fault is still found to exist after three cycles the valve N is opened and an alarm is activated to have suitable personnel attempt too locate the fault in the delivery line associated with valve N.

(d) If after the valve N is reopened on the completion of the third period of time the vacuum pumps are deactivated before completion of the second period of time this is an indication that the fault has been rectified and the sewerage system reverts to its normal operation.

(e) If during the sequence the vacuum pumps continue to operate on closure of the valve N this is indicative of a general failure and in such an event the valve N is opened and an appropriate alarm is activated.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiments or examples of the embodiments described above.

Claims

ClaimsThe claims defining the invention are as follows:

1. A vacuum sewerage system control wherein said vacuum sewerage system comprises a central collection zone and a set of at least one intermediate collection zone where each intermediate collection zone is connected to a set of sewage sources, each intermediate zone connected to a vacuum source through a delivery line to maintain the at least one delivery line in a state of vacuum, the inlet for each delivery line from the respective intermediate collection zone being controlled by a valve which is adapted to open selectively to deliver the contents of the intermediate collection zone into the delivery line, a monitor means for sensing an adverse condition in the at least one delivery line, said adverse condition being a condition indicative of the presence of a low vacuum state in said at least one delivery line for an undesirable length of time, said monitor means to provide an activation signal to a control means on the sensing of an adverse condition, the control means adapted to adapted control access between the at least one delivery line and the vacuum source, whereby the control means will isolate the at least one delivery line from the source of vacuum for a period of time in the event of an adverse condition and provide access between the at least one delivery line and the source of vacuum on the expiration of the period of time.

2. A vacuum sewerage system control as claimed at claim 1 wherein the vacuum source is connected to the at least one delivery line through the central collection zone.

3. A vacuum sewerage system control as claimed at claim 1 or 2 wherein a plurality of delivery lines are controlled by the control means.

4. A vacuum sewerage system control as claimed at claim 3 wherein all of the delivery lines are connected to a common vacuum source.

5. A vacuum sewerage system control as claimed at any one of the preceding claims wherein the vacuum source comprises at least one vacuum pump.

6. A vacuum sewerage system control as claimed at any one of the claims 1 to 5 wherein the vacuum source comprises at least one vacuum reservoir and at least one vacuum pump.

7. A vacuum sewerage system control as claimed at any one of the claims 7 wherein, at least one of the at least vacuum pumps maintains the vacuum reservoir in a state of vacuum.

8. A vacuum sewerage system control as claimed at claim 5 or 6 or 7 wherein the control means controls operation of at least one of the at least one vacuum pumps to control access between the at least one delivery line and the vacuum source.

9. A vacuum sewerage system control as claimed at claim 6 or 7 wherein the control means controls access between the at least one delivery line and at least one of the at least one vacuum reservoirs.

10. A vacuum sewerage system control as claimed at claim 6 or 7wherein the control means controls access between the at least one delivery line and at least one of the at least vacuum reservoirs and between the at least one delivery line and at least one of the at least one vacuum pump, whereby the at least one delivery line is caused to access both the vacuum reservoir and the vacuum pump on expiration of said period of time.

11. A vacuum sewerage system control as claimed at any one of claims 1 to 4 wherein the vacuum source comprises at least one vacuum reservoir which is maintained in a state of vacuum.

12. A vacuum sewerage system control as claimed at any one of claims 1 , 2, 3,11 and claims 5 ,6 7and 10 as dependant from claims 1 , 2 and 3 wherein the control means controls a valve for providing access between the at least one delivery line and the vacuum source.

13. A vacuum sewerage system control as claimed at any one of claims wherein the control is adapted to prevent the reactivation of the control means in the event of a prescribed number of sequential adverse conditions having been sensed.

14. A vacuum sewerage system control as claimed at any one of any one of the preceding claims wherein the monitoring means monitors the period of continuous operation of the vacuum pump in sensing the presence of said adverse condition.

15. A vacuum sewerage system control as claimed at any one of claims 1 to 13 wherein the monitoring means monitors the state of vacuum in the at least one delivery line in sensing the presence of said adverse condition.

16. A vacuum sewerage system control as claimed at any one of the preceding claims wherein a plurality of delivery lines are controlled by the vacuum sewerage system control and said control means is adapted to separately control access between each delivery line and the vacuum source

17. A vacuum sewerage system control as claimed at claim 16 wherein each delivery line is provided with a valve which controls access between the respective delivery line and the vacuum source and said valves are controlled by the control means.

18. A vacuum sewerage system control as claimed at claim 16 or 17 wherein on an adverse condition being sensed the control means is adapted to sequentially control access between each delivery line and the vacuum source to locate the delivery line causing the adverse condition.

19. A vacuum sewerage system control substantially as herein described.

20. A method of controlling a vacuum sewerage system wherein the vacuum storage system comprises at least one intermediate collection zones where each intermediate collection zone is connected to a set of sewage sources, each intermediate zone connected to a vacuum source through a delivery line to maintain the at least one delivery line in a state of vacuum, the inlet for each delivery line from the respective intermediate collection zone being controlled by a valve which is adapted to open selectively to deliver the contents of the intermediate collection zone into the delivery line said method comprising monitoring a condition indicative of the state of the vacuum in the at least one delivery line to sense the presence of an adverse condition, said adverse condition being a condition indicative of the presence of a low vacuum state in said at least one delivery line for an undesirable length of time, activating a control means on sensing an adverse condition to isolate the vacuum source from the at least one delivery line for a period of time and to provide access between the at least one delivery line and the vacuum source on expiration of that period of time.

21. A method of controlling a vacuum sewerage system as claimed at claim 20 wherein the control means controls a valve to control access between the at least one delivery line and the vacuum source.

22. A method of controlling a vacuum sewerage system as claimed at claim 20 wherein the control means controls operation of the vacuum source to control access between the at least one delivery line and the vacuum source.

23. A method of controlling a vacuum sewerage system as claimed at claim 22 wherein the vacuum source comprises at least one vacuum pump.

24. A method of controlling a vacuum sewerage system as claimed at any one of claims 20 to 23 wherein the control means is not activated in the event of a prescribed number of sequential adverse conditions being sensed.

25. A method of controlling a vacuum sewerage system as claimed at any one of claims 20 to 24 wherein the increase in vacuum in the at least one delivery line on reactivation of the vacuum generator is rapid.

26. A method of controlling a vacuum sewerage system as claimed at any one of claims 20 to 25 wherein the sewerage system comprises a plurality of delivery lines and the control means sequentially controls access between each delivery line and the vacuum source on an adverse condition being sensed to locate the delivery line which is the cause of the adverse condition and on location of the delivery line which is the source of the adverse condition sequentially controls access between the delivery line and the vacuum source until an adverse condition is absent or until a prescribed number of sequential adverse conditions has been sensed.

27. A method of controlling a vacuum sewerage system substantially as herein described.