Are you considering switching from a heat exchanger to direct steam heating? Here are a few things you need to know.
Many process engineers understand that there are advantages in using direct steam rather than heat exchangers to heat fluids but are hesitant to switch from a technology they understand because they are not familiar with direct steam heating.
Most process people are aware of the advantages of direct steam over a heat exchanger:
- Significantly smaller installed footprint
- Up to 30% energy savings compared to an indirect heat exchanger
- Much faster temperature response compared to a heat exchanger
- Ability to heat many fluids that would foul tubes or plates
- No condensate return system to maintain
Despite the advantages, there are aspects to direct steam that are important to understand to have a successful application. Among them:
- Pressures matter in direct steam. The steam pressure must be higher than the liquid pressure to function.
- There is no lag in the heating process for direct steam. Changes in steam flow instantly change the discharge temperature. The temperature control loop needs to be designed for this behavior.
- It is important to isolate the steam from the heater during down times. Even a small amount of steam leakage can overheat the process.
- Check valves are important in the process to avoid backflow of either steam or fluid into the other line.
Much more information on this topic can be found at pro-sonix.com.
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