The high-temperature gas streams found in sulfuric acid production can present serious mechanical design challenges throughout a facility.
Elevated temperatures and potentially corrosive streams often result in failures that impact reliability and uptime. While careful planning during the initial design phase is ideal, most operators must improve reliability in existing systems.
At CG Thermal, the process starts with a thorough audit of general arrangement and equipment drawings, operations data logs and standard operating procedures. Just as critical are the insights gathered from conversations with maintenance, project and reliability teams. These firsthand accounts offer context about failure patterns, attempted solutions and long-term system behavior.
Using operations data, Computational Fluid Dynamics (CFD) and Finite Element Analysis, CG Thermal’s high-temperature engineers pinpoint the mechanisms that lead to failures, which can include thermal expansion, corrosion or pressure-related issues.
Once the failure mechanism is understood, the team applies decades of experience to engineer solutions. These may include optimized flow paths, revised materials of construction or transitioning from rectangular to round geometry to reduce stress concentrations.
CG Thermal’s AirBTU Variable Pitch Radial Recuperator (VPRR) is a prime example of how recurring cold-end and interpass exchanger failures are eliminated. Designed to withstand the rigors of sulfuric acid production, it addresses:
- Weld failures due to differential thermal expansion
- Cold-end corrosion and fouling
- Flow restrictions from excessive pressure drop
Traditional shell-side expansion joints don’t solve the root cause of weld failures — tubes expanding at different rates. The variable pitch tube design promotes uniform temperature across the tubesheet, allowing uniform thermal expansion. Proprietary baffle and pass designs optimize gas flow, guiding it to achieve target wall temperatures while minimizing stress.
Boosting reliability with data-driven heat exchanger solutions
A large AirBTU VPRR is being loaded for transport to a sulfuric acid production plant.
To mitigate cold-end fouling and corrosion, CG Thermal’s models identify zones where material temperatures drop below the dew point. Design elements such as annular inlet plenums and specialized baffle configurations are incorporated to prevent dew-point condensation, extending equipment life.
Accurate pressure drop modeling is essential. An unexpected drop can affect the exchanger and system performance, reducing throughput. CFD and wall temperature mapping help fine-tune tube pitch and baffle arrangements to meet thermal and hydraulic goals without costly oversizing.
Following this methodology consistently leads to a two to three-times improvement in operating life compared to conventionally designed exchangers.
Beyond gas phase design, CG Thermal addresses the challenge of weak acid cooling with the Umax® Advanced Ceramic Heat Exchanger. Used in sulfuric acid dilution and cooling, it features corrosion-proof SiC tubes backed by a lifetime warranty. Its proprietary elastomeric sealing system allows individual tubes to be removed and replaced in the field with basic tools — no special training or equipment required.
With a smooth, fouling-resistant surface and unmatched chemical durability, the Umax® ensures more uptime and less maintenance. Repairs can be made within a single shift, meaning minimal interruption to production.
Whether addressing corrosion, thermal stress or pressure drop, CG Thermal combines simulation, engineering and field-proven design to deliver longer-lasting, more reliable performance.
For more information, visit cgthermal.com.
