91���˶���Ƶ

As production of renewable fuels increases, refiners will need to overcome operational challenges related to variable feedstock blends — chief among these is heat exchanger fouling.

In the past few years, production of renewable diesel and sustainable aviation fuel (SAF) has skyrocketed. This rise has been driven by economic incentives, subsidies, and national, state/provincial, and local governmental regulations that require reductions in the carbon intensities of fuels. The emergence of these policies coincided with societal shifts motivated by the COVID-19 pandemic, which reduced petroleum-based fuel demand and drove conversion of refinery units. As these units were modified to process renewable feedstocks, new economic value chains were created.

Typical feedstock sources for renewable fuel units include soybean and other vegetable oils, used cooking oils, distillers corn oil, recycled animal fats, and various blends of each of these components. Each source has a different market price and carbon intensity, making each particular unit’s feedstock blend of choice an optimization exercise similar to traditional petroleum crude blending optimization.

A typical renewable fuel processing unit may consist of a pretreatment section; a renewable diesel unit comprising a hydrotreating section, a water separation section, and an isomerization section; followed by a product recovery section. These units are susceptible to many operational challenges, chief among them is heat exchanger fouling.

The significance of heat exchanger fouling in renewable fuel production is substantial. It exceeds mere operational disruptions, notably affecting the industry by increasing operational costs, diminishing efficiency, reducing unit run lengths, and posing potential risks to personnel and the environment. Effectively addressing and mitigating these challenges is crucial for cultivating safe, cost-effective, and environmentally conscious production methods.

This article provides a brief background on the rise of renewable feedstock processing units, describes typical unit operations and feedstock types, and discusses some of the observed heat exchanger fouling types and the mechanisms that generate these foulants. This article also presents treatment solutions, including antifoulant chemistries, as well as operational experiences and expertise to counter these fouling issues...