Wireless helps Hexion with smoke detection, control room reporting
By Control Engineering Staff -- Control Engineering, 8/7/2008
Specialty chemical producer Hexion says it solved smoke detection and control room reporting challenges using wireless technologies. “We had to find a better way of detecting when there was a problem at our multiple warehouses and communicating this, to ensure the safety of our employees as well as to improve reporting conditions to our control room. After investigating several hard-wired options, we found an easy, flexible and affordable way to meet our requirements and improve smoke detection and increase plant reliability thanks to Honeywell’s wireless transmitters,” explains Herman Punt, discipline engineer QMI at Hexion.
| Wireless application: Chemical manufacturer |
| Wireless system helped the application: -Cost one-third original estimates; -Improve reporting; -Meet regulatory requirements; and -Enable real-time detection in case of any incidents. |
Headquartered in Columbus, OH, Hexion Specialty Chemicals makes binder, adhesive, coating and thermoset resins for wood and industrial markets. The company employs 7,000 in 126 production facilities and distribution channels in 25 countries.
At its production site in Pernis, Netherlands, Hexion faced dealing with a legacy communication, reporting, and smoke detection system. After having acquired this expoy resin plant from Shell a number of years before, the smoke detection system of several warehouses associated with the plant no longer met current requirements. That, in conjunction with an antiquated system for sending reports to the control room, acted as a catalyst for a much needed technology makeover. A wireless system from Honeywell Process Solutions. provided the answer.
Hexion selected Honeywell’s XYR 5000 wireless transmitters to improve reporting, meet regulatory requirements and enable real-time detection in case of any incidents. Benefits include the following:
• Wireless transmitters were installed at less than one-third of the estimated costs of the project;
• Reliable, immediate and accurate data helped meet and maintain regulatory requirements;
• Easy access to multiple warehouse data and improved reporting and communication to the central control room improved safety and performance; and
• Lower operational and maintenance costs.
Hexion’s production site in Pernis were part of a complex previously owned by Shell; after the sale smoke detection alerts and possible fire reports were still handled by the incident room at Shell. A technology upgrade for the smoke detection system was needed to meet regulatory requirements. The antiquated control room reporting system also needed an upgrade. Prior system alerted Hexion warehouses only via a manual phone call in case of a smoke warning.
Responsible for proper functioning and possible replacement of analytical instruments, Punt was assigned to select the necessary equipment for the smoke detection and reporting system for the warehouses. Three onsite Hexion warehouses must meet safety requirements for the storage of certain chemicals. Because two warehouses must comply with stringent explosion safety regulations, fast detection of possible smoke is required.
Warehouses are divided into several zones. Signals from the detectors in those zones are first collected at a smoke reporting unit outside the building. Status must be transmitted to the central Distribution Control System in the control room, culminating in an alarm message to process operators.
For conventional cable, expensive cable guiding or digging would have been needed to connect bundles of cables from three warehouses into three cable boxes and to the distributed control system (DCS) in the operating room of the factory. Total distance is about 875 yards, and cables had to be protected against damage. Because the existing cable lanes were already packed, this would have meant adding new cable lanes; a wireless connection between the smoke reporting units and the DCS cost less.
After initial research on the wireless field equipment available, Punt contacted Honeywell. Honeywell XYR 5000 wireless transmitters were “implemented for only one-third of our originally estimated costs,” said Punt.
Smoke detectors in each zone are connected to a reporting unit; each of eight units is connected with cable to a wireless transmitter, which sends signals to a central base radio placed in a high position in the neighborhood control room. From there, the signal goes through a standard RS-485 cable to the DCS. Each smoke reporting unit can send three alerts, Punt says: a smoke alarm, a system failure alarm, and a manual alarm.
To reach maximum signal strength, Hexion conducted a field survey to determine the optimum wireless transmitter placement options. Punt says moving a transmitter as little as 70 centimeters could increase signal strength. Reliable radio contact between transmitters and receivers also was established.
Punt says cables from smoke reporting units to transmitters on the other side of the warehouse, nearer to the receiver, could be skipped, saving more money.
Some transmitters are located on a side of a warehouse, where train and truck traffic passes. Every transmitter has a helical antenna, so the signal is transmitted in all directions, eliminating the need to target the antenna. Each transmitting station also has a battery in the middle and the antenna in a corner.
For optimal transmission, it is best to place the antenna in the direction of the receiver.
Range of a standard transmitter is 600 to 800 meters. Up to 1,500 meters, a yagi-antenna can be used, sending a cigar-shaped signal in one direction. Transmission distances of several kilometers can be reached with repeaters. Hexion uses a star network at 886 MHz, with 5 MHz bandwidth, enough for the 15 to 18 transmitters.
Frequency hopping secures the network. If a frequency is disturbed, the base receiver switches channels. The base receiver regularly invokes connected transmitters and asks for information about transmitting power, the connection, and other diagnostics, within milliseconds, so the risk of possible interference – already small and normally existing only for older unshielded equipment – is minimized further.
Temperature and pressure can be measured and transmitted with addition of appropriate transmitters.
The system has operated without failure since starting operation in January 2007.
Learn from other wireless applications.
– Edited by Mark T. Hoske, editor in chief
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