Originally posted on Automation.com by Shuji Yamamoto, Wireless Solutions Specialist, Yokogawa
Temperature control of exhaust gasses coming off various combustion processes in refineries and related facilities is often critical to effective pollution abatement and compliance with applicable regulations. There are specific temperature windows where toxic gasses can form or other substances can condense, causing corrosion and other harmful effects, so operators need to make sure the process is running at the correct levels.
Stacks, chimneys and other gas handling equipment can take all sorts of forms depending on the application. Some may include scrubbers, gas cooling, chemical injection, afterburners or ambient air mixing—but a common element is the need for effective temperature measurement of the gas at various points in chimneys (Figure 1).
Given the length and height of a chimney, its associated ductwork and ancillary systems—there can be dozens of sensors inserted at strategic points from one end to the other—providing the process automation system and the plant operators with critical temperature data. These sensors are often in hard-to-reach locations where installation and maintenance are difficult. While these sensors are often spread over a great distance, they must connect back to one central point where the larger gas treatment system is controlled.
Figure 1. Chimneys found in refineries and other hydrocarbon processing facilities often require temperature monitoring.
Monitoring a Refinery Main Chimney
At a refinery in the Americas, the main chimney is located 300m away from the main control room, and there are about 30 temperature sensors mounted on the structure, the highest of which are 30 m above the ground. Wiring for such an installation was going to very challenging, so the company instead installed an ISA100 wireless network.
When the refinery was designing the system initially, it was clear the cost of individual wireless transmitters for each temperature sensor would be expensive and take too long to install. To alleviate these issues, the refinery selected Yokogawa YTMX580 Multi-Input Temperature Transmitters, each of which can accept up to eight individual sensors and send the data back via a single wireless transmitter (Figure 2). Each unit can accommodate a variety of RTD and thermocouple types to meet application demands.
This approach minimizes the amount of required wiring while also cutting the cost of the wireless infrastructure. Four of these multi-input transmitters are installed at the facility to service the group of temperature sensors, eliminating the need to add cabling to the control room. The plant’s wireless network backhaul infrastructure brings data from the chimney to the operators so they can monitor system performance in real-time.
The success of this installation has given the plant the confidence to extend the ISA100 wireless network using Yokogawa’s Plantwide Field Wireless infrastructure.
Figure 2. Wiring temperature sensors installed in a chimney back to a control room can be challenging and expensive, so many plants and facilities are instead implementing wireless solutions, such as this Yokogawa YTMX580 8-input temperature transmitter.
Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.
In the ever changing marketplace, refineries are seen not only as crude processing units but also as profit centers. At the same time, there is a keen awareness of the need for safety at such facilities. A total production solution that encompasses planning, scheduling, management, and control is required to achieve long-term goals for profitability, efficiency, and environmental protection. With years of expertise in the automation field, Yokogawa can bring you affordable total solutions for improved operability and a cleaner world.
YTMX580 can accept inputs from up to 8 points of measurement such as thermocouples (8 types: K, E, J, etc.) or RTD signals (3 types: Pt100, etc.), converting the corresponding measurement input values to a wireless signal. It can also accept DC voltage, resistance, and 4 to 20 mA DC signal input.
The flexibility of wireless solutions enables less investment in infrastructure while providing greater insights into plant operations.
Yokogawa offers the dual-input YTA510 and the multi-point YMTX580 temperature transmitters.