Water/Wastewater Industry Application

Rockwell and Data-Linc Group provide Lijiang with reliability, expandability, confidence and clean water

Abstract
Lijiang Water Authority needed 1.) an easy-to-implement means of expanding their existing water system while utilizing legacy equipment and 2.) to build this system in an area covering difficult terrain. In addition to these two technically challenging conditions, it faced a third: to win over the people of Lijiang from skeptacism caused by frequent shut-downs of the existing pipelines that turned them toward reliance upon old dependable wells with compormised water quality. Shanghai Saier Automation Company, a Rockwell Automation system integrator, worked closely with Encompass partner Data-Linc Group to design and install a new water system control and monitoring network that overcame the terrain communications challenge, incorporated existing equipment and ensured the dependable delivery of clean, safe water to the people of Lijiang.

Background

The county of Lijiang in Southern China boasts a spectacular setting of mountains, glaciers and forests as well as an 800-year history dating back to the ancient Naxi Kingdom. Its population numbers only 350,000, but because of its status as one of the world’s major cultural heritages— established in 1997 by UNESCO, it hosts over two million tourists a year with the number projected to rise to over 5.5 million by the end of 2005. This tourism boom places an extraordinary and growing demand on Lijiang’s infrastructure in general and its water system in particular.

Need

Meeting the water needs of the residents alone challenged the available supply from a system designed to produce about 20,000 tons of water per day, but the demand placed upon it by visitors posed an additional burden. Because the water supply is piped from a local river spawned by mountain run-off, it becomes excessively turbid during heavy rains. The river conditions then forced the Lijiang Water Authority to close down the system for long periods at a time. These regular shutdowns obliged residents to resort to ancient water wells that have compromised water quality and often resulted in high pH levels.

Plan

Plans for the area included not only economic development but also improvement of the county’s water supply. The water upgrade program offered a two-phase approach: Phase I would increase the water capacity to 40,000 tons a day and Phase II to 60,000 tons a day. The plan was based upon a new 60,000 cubic meter reservoir with a pumping station to transfer fresh water 2.5 Km to a new water purifying plant built next to the river, a parallel water source. After purification, the water would be pumped throughout the county.

Challenges

With this plan, the Lijiang Water Authority had taken a major step toward consolidating water system reliability but it still faced a number of challenges the most significant of which involved client confidence, system expandability and operation in a difficult terrain. The first challenge involved water system control and monitoring to ensure continuous system performance and specific water quality standards. Meeting this challenge would win the confidence of the people and convince them that the new system was safe and reliable so they would give up use of their well-based source. Second, the adopted system would require scalability to be fully integrated across the county and to have the capacity to expand with the growing need. Finally, the beautiful but difficult terrain that needed to be traversed— from the pumping station to the purification plant and throughout the county— presented interesting and challenging barriers to data transfer across the new water system.

Solution

In September 2001 the Lijiang Water Authority selected the Rockwell Automation system integrator Shanghai Saier Automation Company to design and install the new water system control and monitoring network. The system integrator worked closely with Encompass partner Data-Linc Group to address the terrain communications challenge.

The system design employs a network of Allen-Bradley SLC 5/04 and MicroLogix 1500 controllers. Four SLC 5/04s provide control and monitoring of pumping, reservoir and water purifying operations, and the MicroLogix 1500s provide local monitoring of pipe system pressures at five key locations across Lijiang. Rockwell’s Software RSView32, a PC-based Human Machine Interface (HMI) system, presents a graphical real time view of the entire system’s performance on two PCs at the main Bashai village water purifying plant control room.

Allen-Bradley’s Data Highway Plus (DH+) network, designed to operate at distances of up to 3.2 Km, covered the 2.5 Km pipeline distance between the pump station and the water purifying plant. But integrating the five water system remote terminal units (RTUs) spread over an area eight kilometers in diameter presented a greater challenge. Options considered and rejected included a fixed wired network, impractical and costly over the arduous terrain; legacy low frequency wireless modems, costly due to required spectrum licenses and also inadequate due to serious interference; and telephone dial-up modems, providing only low data rates and potential reliability problems with the telephone lines.

Data-Linc China proposed an alternative technology: the license-free SRM6100 wireless modem series. Data-Linc visited the Lijiang site and conducted extensive signal strength and Carrier to Interference Ratio (CIR) tests, before deciding on the specific transmit/receive sites. “The advantages of the SRM6100 in the Lijiung application are very clear,” says Data-Linc China engineer Zhang Wenyang. “Operating in the 2.4 Ghz band it requires no spectrum licenses, it provides a high data throughput, and is specially designed to avoid jamming and multi-path interference problems (See SmartSpectrum^TM Technology.).” The SRM6100 also provides virtually infinite expandability in point-to-multi-point configuration, and integrates directly to the SLC 5/04 and MicroLogix 1500 RS232 ports without the need for additional converters. (Please see following diagram.)

Conclusion

Phase I of the Lijiang water control and automation system was completed in July 2002 and is completely operational, helping to ensure the new water system’s total reliability — and it has provided a remarkable 100% improvement in the water system throughput capacity. Supported by Data-Linc license-free technology, the five RTU stations provide vital monitoring of the system’s performance across the county, presenting Lijiang Water with critical real-time data and confidence in the system’s status.

Balancing the purifying plant’s two water sources and fully automating water treatment have improved the county’s water quality and dependability. With the new system reliably providing world standard, crystal clear water, the water authority reported an increase in customer demand of 25% within just a few months after commissioning. Because of the system’s benefits, the people of Lijiang are leaving their old well-based source for the safe and reliable water produced by the new automated system.

Because of Data-Linc modems, Lijiang Water Authority has now an easy-to-implement means of expanding the current water system, has confidence in the modems’ ultra reliable data transfer despite communicating across difficult terrain and thus has met two of its most difficult challenges in addition to the third which is well on its way— winning over the people of Lijiang to the new system.