Vaporizing Regulators Help Maximize Analyzer Uptime
by Luke Wurban, on Wed, Feb 12, 2020 @ 14:02 PM
Improvements to Swagelok's KEV Series mean better performance
Swagelok's improvements to its KEV Series Heated Regulators include better components and features that can prevent costly downtime. It has been designed to simplify assembly and maintenance in a way that is ergonomic and intuitive to help minimize the potential for operator errors, asset damage, and incorrect readings.
Turn up the heat
Suppose your process stream is liquid but you need a vaporized sample for analysis by a gas chromatograph. Likewise, you may need to apply heat in order to replace heat lost after a drop in pressure for gas systems, preventing condensation. In both cases, it's time to turn up the heat using a vaporizing regulator.
While it may sound simple — just heat the sample and analyze — an incorrectly designed system can result in incomplete vaporization, additional unwanted fractionation, and possibly long time delays. Here are a few challenges to be aware of, and how the Swagelok KEV Series of heated regulators deals with them.
Heat, but not too much
In general you need heat to vaporize a sample, but you don't want the heat to change the sample’s composition. You also want to avoid incomplete vaporization, fractionation, and excessive time delay. And the vaporizing equipment needs to remain reliable, even when there are changes in pressures along the flow path, changes in ambient conditions, or changes in operator inputs.
Different materials will put a different load on a vaporizing regulator. For example, it takes more energy to change the temperature of a fluid that's very cold, has a high density, or has a high flow rate.
If this thermal load drops dramatically (such as when an upstream valve is closed), there may be excess heat within the body, causing the thermal safety fuse to trip and cutting off all power to the heater element.
Similarly, if the load increases (such as when a flow control valve opens too far), the heater controller quickly delivers more power to the heater. This quick reaction can lead to a temperature overshoot, which likewise could trip a thermal safety fuse.
In the past year, Swagelok has made big improvements to its KEV Series Heated Regulator design to improve reliability and responsiveness by allowing for thermal feedback and adjustment to changing conditions.
The amount of power delivered to the KEV Series regulator is proportional to how far the temperature is from the regulator setpoint, the amount of time spent above or below the setpoint, and the rate of change of the temperature.
The KEV Series uses a Proportional Integral Derivative (PID) controller to manage the power level of the heater. The model was refined and tested by simulating its response under a variety of thermal load conditions. The simulation results were then correlated with actual data. The result is a well-tuned PID control loop that reacts quickly to changes in thermal load without overshooting or undershooting the target temperature.
Ambient temperature effects
It is common to install vaporizing regulators within heated enclosures. When designed correctly, they should run just fine. However, vaporizing regulators are often installed close to the enclosure heaters —in the worst case, directly above the heater. Since heat rises, the temperature surrounding the regulator will rise. That may work in steady-state conditions, but it will be difficult to shed any excess heat if the regulator must react to a change in flow or thermal load.
The KEV Series Regulator adapts to these challenging environmental conditions. An automatically re-settable, embedded thermal switch notifies the heater controller when overheating is imminent. The controller responds by interrupting power to the heater. Once the thermal switch resets, the controller automatically adjusts power output and resumes normal PID control. Learn more about our KEV Series Heated Regulator by downloading the one-page quicklook info sheet.
Vaporizing regulators are not plug-and-play units. Analytical sample systems that include vaporizing regulators must be initially adjusted and maintained on a regular basis. Operators must know how to set proper power levels.
Fortunately you aren't left on your own with the KEV series. Our field engineers will properly size it and set it up using specialized software. Proper sizing of vaporizing regulators is a key to success. Every stream has a different composition, and these numbers are key ingredients to an efficient analytical system.
We're ready to help
The improved design of the Swagelok KEV Series Heated Regulator can react to changing thermal loads, can adjust power output to match system conditions, and can compensate for power levels. This keeps sample systems running well, maximizes your system’s effectiveness, and minimizes costly downtime. Click here to learn more about the regulators that we have available.
Edmonton Valve & Fitting is an expert on regulators, and we know how to advise and help. Put that combination to work for you by calling 780-437-0640 to ask about our KEV Series Heated Regulator, or send us a note through our website. Also ensure you're up to date with all Edmonton Valve & Fitting news and product launches by following us on LinkedIn.