In this issue of Process Heating, we look at how effective selection, operation and control of individual components result in optimized processes.
First up is “Thermal Expansion Tank Design and Operation,” which looks at how a properly sized expansion tank serves as the main venting point for a heat transfer fluid heating system as well as acts as a reservoir for fluid circulating through the system. The expansion tank serves the essential functions of purge point for noncondensable gases and provider of suction head to the circulation pumps.
Sizing isn’t the only design criterion to consider, of course. Once a system is sized properly for the production rate, effective control can help optimize operation. “Control Oven and Dryer Dampers for Energy Savings” suggests that by employing damper controls on ovens and dryers, thermal processors can tune their equipment to avoid heating air just to send it out the exhaust stack. While NFPA 86 requirements and some products require a minimum amount of excess air, and that criteria should always be observed, for those applications that can minimize airflow through the oven or dryer safely, damper controls interlocked with gas detection and solvent-monitoring devices offer a way to reduce fuel use. In particular, the article explains how using a solvent vapor-monitoring analyzer can precisely measure and safely allow proper modulation of fresh air or exhaust from an oven or zone, thereby maximizing fuel savings while helping to secure plant safety.
Speaking of plant safety, the OSHA standard for the control of hazardous energy — known as lockout/tagout — outlines specific actions and procedures for addressing and controlling these hazards during servicing and maintenance of machines and equipment. OSHA 29 CFR 1910.147 outlines the specifications, and in “Securing Plant Safety,” Barry Atkins of Portable Appliance Safety Services (PASS) Ltd. looks at specific guidance provided by the government agency.
In order to effectively control a process, it is important to capture all of the data being generated by its control instrumentation. “WirelessHART: A Natural Progression in HART Protocol” explains how the networking protocol uses two types of wireless transmission technologies to capture data that otherwise would be isolated from the system. Wireless technologies allow plants to connect even difficult-to-reach devices without having to run wiring.
Linda Becker, Associate Publisher and Editor,