The Challenge

Optimization of the Crude Distillation Unit process conditions is the main challenge for every refinery.

Continuous real time monitoring of the feedstock and outgoing istillates is a minimal requirement for ensuring:

  • Minimal influence on the production capacity of each distillate due to changes in crude oil.
  • Maximum production of high value distillates at the expense of heavier distillates of lower value.
  • Stability of the CDU operation conditions.
  • The prevention of production of off-spec material.

Economic Drivers

The problem is maximizing the production of the distillates according to the following properties:

  • Distillation points: IBP;T10;T50;T95;IBP
  • Cloud point
  • Freeze point

Naphtha is worth more than Jet Fuel
Jet Fuel is worth more than Diesel Oil
Diesel Oil is worth more than Fuel Oil
Fuel Oil is worth more than Residual

  • Using Diesel as an example: any distillate with a T95 higher than 315ºc should not get into the Diesel cut. This distillate adversely affects the combustion and cold properties of Diesel Fuel.
  • Since refineries are unable to measure properties such as T95 quickly and accurately enough, they set their operational targets at a safety margin of 10% below 315ºc. This means that they are ‘giving up’ on a fractional difference of the lower margin (less valuable) atmospheric Fuel Oil cut.
  • As a result: 10% of Fuel Oil is lost to Residual; 10% of Diesel Oil is lost to Fuel Oil; 10% of Jet Fuel is lost to Diesel Oil and 10% of Naphtha is lost to Jet Fuel
  • Therefore, based on a refinery’s operations, (temperatures, draw rates, crude feed rates, etc.) and with an appropriate analyzer (such as the AI-60 Petroleum Analyzer) the refinery can push its control limits higher and get extra high end product.
  • Based on a conservative calculation, the Aspect AI-60 enables the refinery to reduce the safety margin to 5% (instead of 10% that currently is being used).

Basic Configuration

Control Parameters

The product streams are monitored continuously during the production and are analyzed by the AI-60 Analyzer.

Data collected from each stream will predict the following physical parameters of the CDU incoming crude and distillates products:

Crude Oil

  • API
  • Distillation
  • Conradson Carbon
  • Water in Crude
  • Ashphaltenes
  • Sulfur

HGO

  • Density
  • Distillation
  • Pour Point
  • Cloud Point
  • Viscosity Index
  • Pariffins
  • Naphtenes
  • Aromatics

LGO

  • Density
  • Distillation
  • Pour Point
  • Cloud Point
  • Viscosity Index
  • Pariffins
  • Naphtenes
  • Aromatics

Diesel Oil

  • Density
  • Distillation
  • Cetane Index
  • Cloud Point
  • Pour Point
  • Viscosity Index
  • CFPP

Kerosene

  • API
  • Distillation
  • Cetane Index
  • Flash Point
  • Freeze Point
  • Aromatics
  • Naphtenes

Naphtha

  • Density
  • Distillation
  • PONA
  • Octane

Case Study Yanshan Refinery

24 May 2020

4IR’s AI-60 Petroleum Analyzer for Optimizing Crude Distillation Unit

Comprehensive and adequate control of the process parameters of the Crude Distillation Unit (CDU) is an obligatory requirement for the optimal production of naphtha, kerosene and gasoil. This has a direct impact on the economics and the profit of the refinery. Integrated real-time and on line monitoring of the feed and the distillates allow immediate […]
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