The Scott Candler Water Treatment Plant (SCWTP) began full-scale production on July
25, 2007. SCWTP has an advanced supervisory control and data acquisition (SCADA) system that monitors feedback from
instruments, valves, and equipment from all of the numerous processes used to meet the
design capacity of 150 mgd. In addition to the traditional
process performance parameters now routinely monitored by modern plant SCADA
systems such as turbidity, chlorine residual, pH, filter flow, and headloss, the majority of
components for all treatment processes are continuously monitored by the SCWTP
SCADA system. Examples of additional components monitored include chemical flows,
chemical tank levels and temperatures, theoretical pump performance, power
consumption for specific processes, and multiple additional process parameters
associated with the ozone system.
The SCADA system at SCWTP is comprised of several different network platforms
including Ethernet, Profibus, ControlNet, and DeviceNet. To accommodate the large
amount of data that is required to move throughout the system, the control system
design segregated the data by creating different networks within the SCADA system to
carry the information. Fiber optic technology was used to provide increased throughput
and increase the speed on the different networks. There are more than 40,000 tags in the
human machine interface (HMI) system alone, which is comprised of redundant servers
and more than 16 clients. The main control of the water treatment plant is being
accomplished by the latest in programmable logic controller (PLC) hardware technology.
Several PLC processors share a common Ethernet backbone, while the HMI system
passes data on another network separate from the PLC's, saving bandwidth and isolating
data streams. Several critical PLCs are backed up using a redundant processor
configuration, making this a cost effective and robust system.
The data on the HMI servers can be visually trended to allow the operators and
maintenance staff the ability to observe process operation in real time. The ability to
create historical trends has been instrumental in solving a variety of unusual occurrences
during plant start-up operations, including mystery overflows into chemical containment
areas; identification of triggers causing ozone system shut downs; and, determination of
the causes of anomalies in what would be considered normal operations of filters,
chemical systems, and ancillary ozone system processes. This advanced SCADA system
was specifically designed to enhance the operability and optimization of the SCWTP and
illustrates the power of the instrumentation and data collection tools that have only
recently begun to be used in the water treatment industry. This paper presents examples of the methodology used by operations and maintenance
at the southeastern United States' largest and most advanced surface water treatment
plant, to utilize the capabilities of their advanced SCADA system and help save time,
money, and headaches. Includes figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1000 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 11/01/2008 |
