|
The mining company RWE power sues ABB’s electromagnetic water meters to help preserve groundwater based marshes and wetlands around its German coal mines. The meters monitor the amount of water being pumped back into the nature reserves from RWE’s open cast lignite mines, where constant pumping is needed to control groundwater levels in three large mines Recently RWE ordered 25 AquaMaster instruments for this purpose.
In the past, RWE used mechanical flow meters to measure the amount of water pumped back into the marshes. The need for more accurate measurements and automatic data monitoring made electronic flow meters an attractive proposition. However, with many of the meters located beyond the reach of mains electricity, it was difficult for RWE to find a suitable electronic alternative for the sites.
AquaMaster meters from ABB provided the solution. Fitted with their own battery power supply, the flow meters can be installed in locations where no mains supply is available. Whenever RWE maintenance engineers find that a mechanical meter has failed, they now replace it with an Aqua Master meter, with a measurement accuracy of ±0.5% over a turndown range of 1000:1, the meters can deliver precise measurements, even at extremely low flow rates, compared with their mechanical counterparts, which can offer an accuracy of only ±2%.
In addition, ABB has now become RWE Power’s preferred supplier of meters to monitor pumping stations in the mines. Here, since the availability of mains power is not an issue, RWE has opted for ABB’s COPA XE, compact electromagnetic flow meters.
Erosive particles in the untreated mine water attack and wear the mechanical meters, sot he company decided to test 11 such units in its mines over a periods of mine months. The units proved so successful that RWE has already ordered a further 35 instruments, ranging in size from DN50 to DN300.
The AquaMaster and COPA XE are just two examples of ABB’s wide choice of electromagnetic flow meters for conductive fluids such as water, pastes, acids, dyes, juices and emulsions, including fluids with a conductivity as low as 0.5 μS/cm.
Tracing Water Leaks
In direct response to this challenge and customers requirements to conserve drinking water, ABB has developed and commercialized a revolutionary new product for the water industry. The new enhanced flow meter, AquaMaster SMS that delivers measurement data from remote locations direct to customers via the Internet, heralds a new era in water leak age management.
The AquaMaster is a product that is on the cutting edge of technology with features and applications that are unique within the water conservation and distribution market.
The latest models of AquaMaster have built in options such as an integrated pressure sensor but also data logging capability and GSM SMS radio technology. The data logging capability is significant in that it allows recording of flow and pressure at a normal rate of every 15 minutes, saving three months of data locally. But in addition and by virtue of the digital connection between the flow measurement and the data logger, high resolution data can be logged at rates not possible with traditional solutions. This is much more significant than it first appears.
Measuring Transient Flows
With a traditional external data logging solution, pulses are captured over the logging interval, but, due to upper frequency limitations by the flowmeter, only a limited number of pulses can be counted in the log interval. So for a meter with a large turndown ratio, it is not uncommon to get measurement or “quantization” errors of around 10 percent or more, the data being very stepped or “quantized” as a consequence. AquaMaster, with its direct digital connection to the data logger, reduces quantization associated errors to insignificant levels. In addition, in a second channel, it offers high speed, high resolution logging at an interval of up to 15 seconds. This is invaluable for capturing transients during network step testing. Within water net works, stet testing is a well established technique for localizing water loss in a zoned distribution system. It requires the establishment of zones, where water can be supplied through a single meter after all boundaries and circulation valves have been closed.
Water Leakage Management
Closure of a valve isolates a specific section of the zone. A large drop in flow indicates a leak within that section. The benefit of AquaMaster in such step testing is best illustrated by comparison of, on a traditional 15 minute log interval with, captured in great detail from the second channels one minute log.
In this step test, one zone valve was closed at 02:30, with a further a one valve closed at around 02:40. From the one minute log, the zone with a significant leak was clearly identifiable from the sudden drop in flow, with a second smaller leak within the second zone. The magnitude of the leak in the two zones is substantial at around 2 m3/hr.
Step testing with AquaMaster is far simpler, cheaper and faster than established practices. It no longer requires a skilled technician with an external step test data logger. All that is necessary is a simple procedure and a person to close a valve at specific pre-agreed times. Also. any disruption to water consumers is minimized by restricting the time a valve needs to be closed to only a few minutes. Within the following week, the high resolution logger can be downloaded and analyzed to identify the source of the water leak. This step testing process is significantly enhanced by the use of radio communication to obtain meter data.
Traditionally, data is logged externally from the flow measurement and recovered manually by sending someone on site to download the data, or sometimes by retrieving the entire data logger and exchanging it with a second one. More recently, customers have switched to using radio for meter reading.
Radio Equipped AquaMaster
ABB’s innovation is to equip AquaMaster meters with the option of GSM SMS radio technology. In 2005 this feature was upgraded to use SMS text messaging to convey flow and pressure data SMS text messages are automatically sent, typically once per day to conserve power in the case of a battery powered device. In the event of a fault, an SMS message is sent as an alarm, eg if the meter is being tampered with.
The AquaMaster also responds to SMS text messages sent to it, such as configuration changes or requests for specific data. Up to three months of data can be stored internally.
Measuring and logging the flow and optionally, pressure are only part of the equation. Getting the collected data onto the customer’s computer, management information or leakage management system is the other part. Discussions with key global customers showed that they could be partitioned into two groups with different requirements:
1) Customers with an existing infrastructure and established water management system.
2) Greenfield customers who have measurement requirements but no back office system to handle the measured data.
To address both customer needs, ABB devised a solution based on delivering remote meter data via SMS text message to virtually any database, using industry standard programming mechanisms.
AquaMaster SMS to unique in that the volume totals from the instrument index register are also sent by SMS text message.
Terry Mizzi
|