Yield is a measure of the amounts of different products that a refinery achieves running a given mix of crudes.

A better yield would be one with more high-valued products (eg gasoline and diesel) of higher quality (eg high octane gasoline, high cetane diesel).

The yield of a refinery is largely going to be pre-determined by the quality of crude that it runs and the conversion units (type and capacity) that it has. However there are a number of operational levers in a refiner’s control that allow it to affect yield (for better and worse) on the margin. These include adjustments to:

Distillation cut points – end points for each distillation fraction, which affects both the volume and quality of each fraction produced.

Unit run rates – Throughput for a given unit

Unit run lengths – Time between taking a unit out of service for maintenance, catalyst replacement, de-coking etc

Unit operating conditions – Severity setting such as temperature, pressure etc that directly affect a unit’s yield and product quality.

Stream routing – Choosing which downstream unit or product blend to send a specific stream to.

Catalyst type and volume – For catalytic units such as the FCC or reformer this can significantly affect unit yield and product quality.

Blending effectiveness – Poor blending of the planned product recipes frequently results in product quality giveaway (blending to qualities that exceed what is required). This is effectively a missed opportunity to sell more of a higher-quality grade and generating higher overall product revenue.