Designing Heat Exchangers to Mitigate Fouling

Fouling in heat exchangers is a common problem that all refineries, petrochemical plants, and other chemical facilities must contend with. Here, basic design considerations for mitigating fouling are discussed.

In a heat exchanger, fouling refers to any unwanted material that accumulates on the heat transfer surface during operation. This accumulation leads to a reduction in heat transfer efficiency and/or an increase in pressure drop. It is an unavoidable outcome of indirect heat transfer across a separating wall. To address this, design engineers consider fouling resistance for both the hot and cold streams when there is a probability of foulant deposition occurring during the operation.

Failing to account for fouling resistance in a heat exchanger may lead to reduced heat transfer efficiency, increased energy consumption, higher pressure drops, frequent maintenance and downtime, shortened equipment lifespan, and inconsistent process performance, as well as economic losses. Considering the correct fouling factor and other design parameters based on the process fluid during the design phase is key to ensuring the heat exchanger operates efficiently, reliably, and economically throughout its intended lifespan.

Most heat exchanger companies follow the Tubular Exchanger Manufacturers Association’s (TEMA’s) fouling guidelines as standards when designing, installing, and operating heat exchangers. However, these guidelines are generic and don’t take into account various parameters, such as the impact of fluid velocity and temperature (except in a limited number of cases) on fouling, which should be considered during the design phase.

This article discusses the different types of fouling that can occur in shell and tube heat exchangers, and highlights some design parameters and sizing considerations to keep in mind during the design phase of the exchanger...