Wireless technology has been used for decades for point-to-point telemetry applications and certainly is attracting growing interest nowadays. After all, wireless opens up the prospect of getting data impossible or uneconomic to get via traditional wired approaches. This goes beyond monitoring equipment currently not instrumented. It also promises to allow plants to take advantage of wired HART-based field devices’ embedded diagnostics now stranded because legacy control systems don’t support HART.
Wireless can lead to more extensive and effective predictive maintenance and better asset management, as well as enhanced speed of response to safety and environmental incidents.
Many plants are eager to try wireless. However, there’s been a sticking point — sites want to be sure that whatever wireless they put in will provide reliability and high performance and won’t become technologically obsolete. Smart Wireless offers that assurance.
Its wireless instruments communicate via a self-organizing field network based on the Time Synchronized Mesh Protocol (Figure 3); new devices connect automatically.
Installation doesn’t require elaborate site surveys or special tools. The network achieves greater than 99% reliability by automatically switching to clear nodes should a blockage occur, and is scalable to thousands of devices. The protocol employs channel hopping and has been shown to tolerate almost all types of interference and to be able to co-exist with other established wireless networks. The network can run as a stand-alone system, delivering significant value without the need for a plant-wide wireless infrastructure, or can be integrated within such an infrastructure.
Installation offers significant savings in engineering, materials and labor compared to wired systems — this can translate to a reduction in the cost per point of as much as 90%.
Smart Wireless also boasts robust security (validated by experts, including those at the U.S. Department of Homeland Security), greater-than-five-year battery life, and, importantly, a guaranteed upgrade path to the wireless standard under development.
Current products in the Smart Wireless portfolio consist of level, pressure, flow and temperature measurement units, on/off indication, and a gateway to transmit wireless data to the host; many more devices, including a HART upgrade module and a vibration monitor will be out shortly. A SmartPack starter kit (Figure 4) contains a wireless gateway and the customer’s choice of from five to 100 preconfigured wireless transmitters for pressure, level, temperature and flow that can be deployed right out of the box without additional user input or setup, as well as AMS Device Manager predictive maintenance software. It also comes with SmartStart Services, which include provision of a technician onsite for the first start-up, verification of device and gateway functionality, and a network health check to ensure optimal connectivity.
Software improves controller performance
Loop-Pro Product Suite Version 4.5 provides plants with an easy-to-use tool to check and enhance the performance of controllers. While the software incorporates highly sophisticated process modeling and tuning routines, it follows a simplified recipe-based procedure that suits it for use by operators and technicians.
Most plants heavily rely on proportional-integral-derivative (PID) control. Getting proper performance from such control loops plays a crucial role in achieving smooth, safe and efficient operation. This usually requires the efforts of control engineers or other specialists. However, such staff often are in short supply and have lots to do, hampering their ability to give adequate attention to many control loops. Other engineers on site generally can’t pick up part of the burden because they learned little about control theory in college. There is an untapped resource, though. Plants usually have far more operators than engineers — one estimate is that there’re 25 operators for every engineer at a typical petrochemical plant. But most operators typically only have a high-school education and so can’t use conventional control loop diagnostic and tuning tools.
The Loop-Pro Product Suite provides a simplified way to apply PID diagnostics and tuning best-practices. It enables operators to conduct thorough analyses of underperforming PID loops, compare potential changes to tuning parameters, and quickly and consistently optimize loops based on simulated PID controller performance and the associated process stability, while validating each step involved in the tuning. Moreover, tuning is tailored to the plant’s particular setup — operators customize the controller parameters based on the site’s distributed control system (DCS) or programmable logic controller (PLC) and unique control objective.
The recipe-based procedure involves 5 steps:
- Open a data file;
- Select and edit data;
- Choose a model;
- Fit the model to the data; and
- Specify a controller.
A lot of effort has been directed at making the software easy to use. For instance, just by moving a slide bar, an operator can alter the balance between controller robustness and speed of response, with the corresponding change in simulated performance visible in real time. Stability is represented graphically, easing interpretation of data and the handling of non-linearity and time-variant systems.
Color-coded alerts draw attention to potential stability issues. Descriptive statistics and robustness values are updated and displayed automatically.
The software provides a complete matrix of PID controller configurations, including P-only, PI, PID and PID with filter. An extensive library of pre-programmed DCS and PLC algorithms reduces the chance of miscalculation and eases the customizing of controller parameters.
Automated PID tuning reports simplify the documentation of analysis and recommendations, and can include user’s observations and other details.