Wireless sensor network monitors key parameters
September 1, 2011 by Guy Crittenden
Waste-to-energy (WTE) plants are very complex technical systems, and Hitachi Zosen Inova AG is among the world’s leading experts in the generation of energy based on waste as fuel. More than 500 plants throughout the world show the company’s professionalism in planning, engineering, dependable project management, commissioning, and on-schedule handover of facilities, with comprehensive packages of services and plant operation on request.
But in order to ensure stable, energy efficient and sustainable operation of WTE plants several subsystems are required: the monitoring process is therefore of key importance to ensure that they work correctly and that all operations are properly integrated.
Hitachi Zosen Inova recently decided to test a new solution to monitor one of their WTE plants: the wireless sensor network solution by Paradox Engineering.
Harsh WTE environments
After the start up of the plant, systems have very often to be optimized, and in this phase the monitoring of process parameters is of major importance. Additionally, distances within the plant are often long, which makes troubleshooting and testing operations complex and time consuming.
In the WTE plant in Lausanne, Switzerland this was exactly the situation: it required a reliable monitoring system which also had to withstand (as in any of such plants) extreme operating conditions. High temperatures, thick concrete walls, moisture, steam; in such environments, monitoring systems must guarantee easy set up, minimal operations, reliability, and help to keep maintenance costs under control.
From among others on the market, Hitachi Zosen Inova selected Paradox Engineering’s Industrial Wireless Sensor Network (PE.WSNi) to overcome these challenges. A first test to verify the reliability of PE.WSNi in the plant in Lausanne was performed: the PE.WSNi node was installed in the waste bunker. It was attached to two microwave radar level measurements via 4-20 mA transmitters. The PE.WSNi gateway was installed in the plant control room, separated from the bunker trough a thick concrete wall.
The gateway stored one-minute level measurements of the waste level in the feed hopper. In this test phase, data was downloaded into .csv format and used first of all as an indicator of system reliability, and secondly for statistics and monitoring.
The expectations of Martin Steiner, R&D project manager, and of Urs Hugentobler, manager project engineering tools, not only related to swift and easy systems monitoring and cost reduction, but the ability to go beyond local data collection and get to the next level of data penetration and measurement.
After a smooth installation phase, the test gave positive results. The only obstacle was the two 4-20mA analog input channels on the I/O module that are not galvanically separated. To overcome this, it was enough to pay particular attention to the connection of external power supplies. A discussion with PE engineers clarified this matter, and the problem was solved using a second 24V supply.
“For troubleshooting and optimization, PE.WSNi allows us to monitor important parameters of the system in a very easy way,” Steiner says. “It allows us to reduce the costs for experimental installations for R&D projects, enabling us to avoid cables and local data collection.”
As a consequence of the successful first testing phase, Hitachi Zosen Inova has decided to implement a second phase in order to evaluate the deployment of the solution on a larger basis. In this phase, PE.WSNi will be integrated with Hitachi Zosen Inova’s data analysis tool, called Pamela: outcoming data will be used for an R&D project studying how to mitigate fouling in WTE boilers.
This time, the analysis will consider data from thermocouples, flow sensors, and pressure sensors, a more complex set of information to handle and a more challenging working environment.
“We are really satisfied with the excellent results of this implementation,” says Gianni Minetti, CEO at Paradox Engineering. “Hitachi Zosen Inova calculated that around 20,000 wired data points are needed to reliably monitor each waste-to-energy plant, estimating an investment of around $ 4,000 per point. Thirty per cent of these can be replaced with wireless data collection nodes, which is quite a substantial saving – and that’s thanks to the PE.WSNI solution.” HMM
Guy Crittenden is editor of this magazine. Contact Guy at firstname.lastname@example.org