Project Synopsis
Develop and evaluate process alternatives for replacing an aging hot oil vapor system at a large chemical manufacturing facility.
Project Summary
The client’s chemical production facility currently operates a hot oil vapor system that includes a natural gas fired Dowtherm vaporizer nearing end of life operation. The unit vaporizes Dowtherm A to supply heat to two (2) reactors which operate at an elevated temperature required for the client’s reaction chemistry.
Currently, there is no backup unit for the vaporizer. Since operation of the reactors may be deemed business critical at times, the client contracted Process Engineering Associates, LLC (PROCESS) to explore options for a reliable replacement heating system for the reactors.
To support this study, PROCESS completed the following initial tasks to determine baseline operation:
- Developed a Heat & Material Balance (HMB) based on current system operation
- Utilized HMB data to estimate the overall heat transfer coefficients for major heat transfer surfaces (first reactor internal Dowtherm coil, and second reactor jacket)
- Utilized the baseline heat transfer coefficients as the basis for the minimum performance of the alternative heating system(s) investigated.
Following those initial baseline efforts, a liquid vs. vapor condensing heat transfer system was ranked according to eleven (11) agreed upon categories with varying importance criterion. Based on that criterion, it was concluded that the facility would benefit more from a liquid heat transfer system (instead of vapor condensing) based on cost, maintenance, and the ability to have a readily available backup (i.e., rental unit).
Within the realm of utilizing a liquid heat transfer system, the reactors hot oil exchangers were further investigated on how to incorporate a liquid heat transfer system. As it relates to the first reactor internal Dowtherm coil, it was concluded that the existing internal coil can be used directly with a liquid phase heat transfer fluid by using a larger mass flow rate, adding larger pumps, and upsizing the return piping.
As it relates to second reactor jacket:
- It was concluded that while it is not feasible to use the existing jacket in a liquid heat transfer system, other options were explored and ranked accordingly to a matrix.
- The highest ranked option for the second reactor (liquid heat transfer system) was found by swapping the service sides of the reactor. (i.e., steam to be applied to the jacket and heat transfer fluid applied to the existing internal steam coil). In this configuration, preliminary calculations suggested a longer heat-up would be required. However, it was found that a larger internal coil could be used for quicker heat-up times, if required.
Lastly, preliminary equipment costs were estimated and provided to the client based on utilizing the aforementioned liquid heat transfer system for the reactors. Equipment dimensional data, potential install locations, and utility requirements were also investigated for the replacement system and provided to the client. This study ultimately provided the client with sufficient details to progress to the next phase of the project in their stage gate process.
Industry Type
Chemicals Manufacturing
Utilized Skills
- Process evaluation
- Heat transfer alternatives evaluations
- Process design.