GB2602095A

GB2602095A - Monitoring arrangement

Info

Publication number: GB2602095A
Application number: GB2020041.6A
Authority: GB
Inventors: Leafe Mike
Original assignee: Enviromontel Ltd
Current assignee: Enviromontel Ltd
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2022-06-22
Also published as: GB202020041D0

Abstract

A monitoring arrangement is described comprising a microwave radar-based level detector 22 operable to monitor the distance between the detector 22 and a water surface, the detector 22 being mounted upon a rigid bracket 24 rigidly secured in a location above a flow channel 10 within which the water, the position of the surface of which is monitored, is located so that the detector 22 is held in a fixed position relative to the flow channel 10. The apparatus is suitable for monitoring spill of water over a spill weir in a waste water treatment works.

Description

MONITORING ARRANGEMENT

This invention relates to a monitoring arrangement, and in particular to a monitoring arrangement operable to monitor and allow logging of spill of water over a spill weir in a waste water treatment works.

In a typical waste water treatment works, waste water enters the treatment works along an inlet flow channel, and treated waste water flows from the treatment works to, commonly, a water course such as a river or the like. There are circumstances in which the quantity of waste water flowing along the inlet flow channel may exceed the capacity of the waste water treatment works. By way of example, such circumstances may arise in the event of usually high levels of flow along the inlet flow channel, such as may occur under storm conditions, or in the event of a failure within the treatment works causing the inlet flow to back up. In such circumstances, the excess waste water may be allowed to flow over a spill weir to by-pass the remainder of the treatment works and enter the water course, such excess waste water entering the water course without having first been treated. There is a desire to monitor the inlet flow of waste water, for example to allow the detection of the occurrence of such conditions, and to monitor the durations of such conditions as, from this data, information regarding the timing and regularity with which untreated waste water is entering the water course can be obtained. Furthermore, when it is detected that waste water is passing over the spill weir, or if it is detected that the waste water level is approaching a point at which spill of waste water past the treatment works will occur, an appropriate alarm can be triggered so that a service engineer can attend to ensure that the treatment works is functioning correctly, One technique by which such monitoring can be undertaken is to monitor the depth of the flow within the inlet channel, and noting when the depth is such that a flow of water over the spill weir occurs. This can be undertaken in an automated fashion using, for example, an ultrasonic sensor to detect the position of the surface of the flow within the inlet channel.

It has been found that the accuracy of the sensors typically used in such applications is relatively low. By way of example, they are only able to detect the position of the surface of the flow to an accuracy in the region of +/-10mm. The accuracy of such sensors is also impacted by temperature fluctuations due to being located in exposed locations, for example arising from sunlight and wind. Condensation and/or deposits on sensor face can also impact upon operation and accuracy. Furthermore, such sensors are typically mounted upon a support that is relatively flexible, and movement of the sensor resulting from deflection of the support can add to the level of inaccuracy associated with the use of such sensors. As a consequence, the outputs of such sensors is typically of relatively little assistance in monitoring for the occurrence of spill conditions and for taking appropriate remedial action.

The Environment Agency's MCERTS scheme determines the standard to which such monitoring equipment must operate, and it is believed that many existing monitoring arrangements are insufficiently accurate to meet the MCERTS standards It is an object of the invention to provide a monitoring arrangement suitable for use in such applications and in which at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

According to the present invention there is provided a monitoring arrangement comprising a radar-based detector operable to monitor the distance between the detector and a water surface, the detector being mounted upon a rigid bracket rigidly secured in a location above a flow channel within which the water, the position of the surface of which is monitored, is located so that the detector is held in a fixed position relative to the flow channel.

The radar-based detector is preferably a microwave based radar sensor, for example an 80GHz sensor. Such a sensor is advantageous in that it can allow detection of the distance of the water surface from the sensor to an accuracy in the region of +/-1mm, and hence determination of the water depth, and so affords a significant improvement in accuracy compared to traditional arrangements. Such a sensor is not affected by being located in an exposed location or by temperature fluctuations, and is not affected by condensation or deposits on the sensor face, and can continue to operate up to the point of being submerged.

The bracket is conveniently of steel, preferably stainless steel construction, designed and fabricated in such a manner that movement of the sensor relative to the channel is less than +1- 0.5mm. It will be appreciated that by mounting the sensor in this manner, accurate measurements of the distance of the water surface from the sensor, and hence of the depth of water can be made. In contrast, with known arrangements in which a sensor of relatively low accuracy is mounted upon a support that is not rigid, measurements can only be made to a very low level of accuracy.

The monitoring arrangement conveniently further comprises a data logger operable to store data representative of the output of the sensor. By way of example, the data logger may be operable to store data indicative of the position of the water surface at fixed time intervals, say every two minutes. However, other fixed time intervals may be used. Data from the data logger may be output to a remote location periodically, for example via a cellular telephone based communications link. By way of example, the data may be transmitted to the remote location at intervals of six hours. Again, the data transmission to the remote location may occur at other time intervals.

In the event that the position of the water surface is detected to be higher than a predetermined level, then the data logger may operate to send an alarm signal to the remote location. The alarm signal may take the form of or include an early transmission of the collected data to the remote location. The predetermined level may be selected to substantially match a level at which spill of water over a spill weir commences. Alternatively, it may be at a lower level to provide an indication that spill of water of the weir is imminent.

Conveniently, the monitoring arrangement includes a power source in the form of a rechargeable battery operable to supply power to the sensor, data logger and transmitter by which data is transmitted to the remote location. A photovoltaic panel and associated controller is preferably provided to recharge the battery.

In order to minimise power use, the sensor and at least part of the data logger are controlled in such a manner as to enter a reduced power consumption mode other than when measurements are being made, data stored and data transmission is being undertaken.

The invention further relates to a waste water treatment works comprising an inlet channel, a spill weir communicating with the channel to allow the escape of excess waste water from the inlet channel, and a monitoring arrangement as set out hereinbefore and operable to monitor the depth of water within the inlet channel.

The invention will further be described, by way of example, with reference to the accompanying drawing, Figure 1, which is a diagrammatic illustration of a monitoring arrangement in accordance with an embodiment of the invention.

Referring to Figure 1, an inlet channel 10 to a waste water treatment works 12 is illustrated, the inlet channel 10, in use, conveying a flow of waste water 14 towards the treatment works 12. A spill weir 16 communicates with the inlet channel 10 and serves to allow excess waste water from the inlet channel 10 to by-pass the remainder of the treatment works 12, in the event that the flow within the inlet channel 10 exceeds the capacity of the treatment works 12, for example as a result of storm conditions or the like resulting in an increase in the flow of water to the inlet channel 10, or as a result of a failure within the treatment works 12 resulting in its capacity being reduced. The spill weir 16 only operates to allow fluid to by-pass the treatment works in the event that the water level within the inlet channel is greater than a predetermined level set by the height of a lip of the spill weir 16.

In accordance with the invention, a monitoring arrangement 20 is provided to allow the depth of water within the inlet channel 10 to be monitored. The monitoring arrangement 20 comprises a radar-based sensor 22 mounted upon a support bracket 24 that, in turn, is secured to part of the structure of the inlet channel 10 so that the sensor 22 is supported above the water flowing within the inlet channel 10. The sensor 22 is conveniently a microwave based radar sensor, for example a 80GHz microwave sensor, and the manner in which it is supported over the water within the inlet channel 10 is such that is can monitor the distance d between the sensor 22 and a surface of the water within the inlet channel 10. The sensor 22 is of good accuracy, for example being accurate to within +/-1mm.

The support bracket 24 is of stainless steel construction, the steel thickness and the shape of the bracket being selected to ensure that, in use, a mounting part 24a thereof upon which the sensor 22 is mounted is unable to deflect by a distance of more than +/-0.5mm in normal use. It will be appreciated that by using a support bracket 24 that is of rigid form, and rigidly secures the sensor 22 in a fixed location, in combination with the use of a sensor 22 of good accuracy, the measurements of the distance d between the sensor 22 and the surface of the water within the inlet channel 10 (which are directly related to the depth of the water within the inlet channel) are of good accuracy, and so with appropriate calibration can be used to provide an accurate indication of whether water is flowing over the spill weir 16.

The monitoring arrangement 16 further comprises a data logger 26 receiving measurement data from the sensor 22, and a transmitter 28 (which may be integrated into the data logger 26) operable to transmit data from the data logger 26 to a remote station, for storage and use at the remote station to allow recordal of, for example, the timing and duration of any spill of water over the spill weir 16. By way of example, the transmitter 28 may use the cellular telephone network to transmit data to the remote station. The elements of the monitoring arrangement 16 are conveniently powered from a rechargeable battery 30, and a photovoltaic panel 32 may be used to charge the rechargeable battery 30. Whilst the use of a battery 30 and photovoltaic panel 32 may be advantageous in a number of locations, through avoiding the need to install mains power supplies or the like for the monitoring arrangement, its use is not essential to the invention and other power supplies may be used.

The data logger 26, transmitter 28 and battery 30 are conveniently located within a housing 34 spaced from the sensor 22, a wired connection conveniently being provided between the data logger 26 and the sensor 22.

Conveniently, the data logger 26 and sensor 22 are arranged such that distance measurements indicative of the distance d between the sensor 22 and the surface of the water, and hence of the water depth within the inlet channel 10, are made at set intervals, for example at two minute intervals. However, it will be appreciated that longer or shorter intervals may be used, if desired. The measurement data is stored in a memory associated with the data logger 26.

The data logger 26 and transmitter 28 are operable to transmit data from the memory to the remote station at set intervals that may be, for example, every six hours, in normal use. However, in the event that it is detected that the distance between the sensor 22 and the water surface is smaller than a predetermined level, indicative that, for example, water from the inlet channel 10 is spilling over the spill weir 16, or that such spilling is imminent, then the data logger 26 and transmitter 28 may operate to transmit an alarm signal to the remote station. The alarm signal may include or comprise an early transmission of the data held within the memory associated with the data logger 26. Upon receipt of the alarm signal at the remote station, a service engineer may be sent to the site to monitor the operation of the treatment works and take such remedial action as is appropriate.

The sensor 22 is conveniently programmed to communicate with the data logger 26 using the Highway Addressable Remote Transducer (HART) protocol, operating in a fully digital manner, enabling enhanced accuracy to be achieved. In the arrangement described hereinbefore, the sensor 22 conveniently comprises a VEGAPULS C22 level sensor, and the data logger 26 and transmitter 28 conveniently comprise a YDOC data logger, a Microlink HART Gateway unit being provided to convert the HART protocol output of the level sensor into an array of Modbus registers that can be read by the YDOC data logger. The transmitter 28 is conveniently of 2G/4G form, transmitting to a suitable MQTT broker and FTP server. It will be appreciated, however, that this represents just one embodiment of the invention, and that other forms of sensor and data logger, etc, may be used.

In order to reduce the power requirements and so allow the elements of the monitoring arrangement to be powered from a rechargeable battery, the sensor 22, logger 26 and transmitter 28 are conveniently controlled in such a manner as to occupy a standby or sleep mode other than when is use. Accordingly, every two minutes (or such other time interval as is desired), the sensor 22 and data logger 26 are powered up for, for example, 12 seconds to allow a distance measurement to be taken and stored, and in normal operation will then return to the standby or sleep mode. Every six hours, when data transmission to the remote station is to be undertaken, the system is powered up to allow such transmission, and is then returned to the standby or sleep mode. The regular transmission conveniently also includes system status information such as battery charge level, system battery consumption, along with a code identifying the site to which the data relates.

Whilst a specific embodiment of the invention is described hereinbefore, it will be appreciated that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A monitoring arrangement comprising a radar-based detector operable to monitor the distance between the detector and a water surface, the detector being mounted upon a rigid bracket rigidly secured in a location above a flow channel within which the water, the position of the surface of which is monitored, is located so that the detector is held in a fixed position relative to the flow channel.
2. An arrangement according to Claim 1, wherein the radar-based detector is a microwave based radar sensor.
3. An arrangement according to Claim 2, wherein the sensor is an 80GHz sensor.
4. An arrangement according to any of the preceding claims, wherein the bracket is of steel construction.
5. An arrangement according to any of the preceding claims, wherein the monitoring arrangement further comprises a data logger operable to store data representative of the output of the sensor.
6. An arrangement according to Claim S, wherein the data logger is operable to store data indicative of the position of the water surface at fixed time intervals.
7. An arrangement according to Claim 5 or Claim 6, further comprising a transmitter by which data from the data logger is output to a remote location periodically.
8. An arrangement according to any of the preceding claims, further comprising a power source in the form of a rechargeable battery operable to supply power to the sensor.
9. An arrangement according to Claim 8, further comprising a photovoltaic panel and S associated controller is to recharge the battery.
10. A waste water treatment works comprising an inlet channel, a spill weir communicating with the channel to allow the escape of excess waste water from the inlet channel, and a monitoring arrangement according to any of the preceding claims and operable to monitor the depth of water within the inlet channel.