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Hydrocracker

HCU Tutorial

 

HCU Simulation

 

Envision Systems HCU Tutorial

 

Copyright © 2009 by EnVision Systems Inc. All rights reserved worldwide.

HCU Tutorial

This interactive HCU tutorial provides an overview, fundamental principles, control principles and operating principles for a hydrocracker unit, using voice, video, animation and graphics. The topics covered are:

Overview

  • Introduction
  • Importance of HCU
  • HCU Compared to Fluid Catalytic Cracking Unit (FCCU)
  • Process Overview   
  • Single-Stage Hydrocracker
  • Two-Stage Hydrocracker

HCU Components   

  • Feed Preparation and Preheat System
  • Reactor System   
  • Reactor Effluent Cooling
  • High Pressure/Low Pressure (HP/LP) Separation System
  • Sour Water Section   
  • Recycle Gas Compressor
  • Make-Up Gas System
  • Fractionation Section

Principles of HCU

  • Hydrotreating Reactions   
  • Hydrocracking Reactions
  • Reactor Conversion
  • Reaction Kinetics
  • Hydrotreating Catalyst   
  • Hydrocracking Catalyst
  • Catalyst Deactivation and Regeneration   

Key Controlled and Operating Variables

  • Introduction   
  • Feed Surge Drum
  • Feed Flow
  • Feed Properties and Composition   
  • Reactor Inlet Temperature and Recycle Gas Furnace
  • Reactor Bed Temperature Controls and Quench System
  • Recycle Gas Flow
  • Reactor Effluent Cooling
  • High Pressure Separator
  • Low Pressure Separator
  • Recycle Gas Compressor
  • Make-Up Gas Compressor
  • Sour Water Section
  • Fractionation Section
  • Poly-Nuclear Aromatics (PNAs)

Safeguard System

  • Introduction    
  • Depressurization Valves
  • Reactor High Temperature Shutdown
  • Reactor Feed Shutdown
  • Recycle Gas Furnace Shutdown
  • Reactor Quench System
  • Low Recycle Gas flow
  • Recycle Gas Compressor
  • Make-Up Gas Compressor
  • High and Low Pressure Separators    

Startup Operations

  • Pre-Startup Check
  • Nitrogen Purge
  • Pressurize with Nitrogen and Start Gas Circulation
  • Catalyst Sulfiding for Fresh Catalyst
  • Heat Reactor, Introduce Hydrogen and Pressurize
  • Introduce Feedstock in Reactor
  • Introduce Normal Feedstock
  • Stabilize Reactor and Achieve Design Operating Conditions

Shutdown Operations

  • Reduce Reactor Temperature and Feed Flow   
  • Feed Out
  • Hot Hydrogen Strip
  • Cool Down
  • CO Purge
  • Depressurize and Ambient Cool Down

Troubleshooting

  • Introduction    
  • Loss of Incoming Feed
  • Loss of Feed to Reactor
  • Reactor Temperature Excursion and Runaway Reactions
  • Loss of Recycle Gas Furnace
  • Loss of Recycle Gas Compressor
  • Loss of Make-up Gas Compressor
  • Nitrogen Poisoning
  • Foaming or Emulsion Problems in HP-Separator
  • Wash Water

 

Envision Systems HCU Simulation
Copyright © 2009 by EnVision Systems Inc. All rights reserved worldwide.

HCU Simulation

The HCU simulation is a rigorous and high-fidelity mathematical process model that provides a realistic dynamic response for a hydrocracker unit.

Process Overview:

The hydrocracker unit converts heavier oils, such as atmospheric/cracked gas oils, vacuum gas oil (VGO) and light cycle oil (LCO) into lighter products, such as liquefied petroleum gas (LPG), light naphtha, heavy naphtha, kerosene and diesel/gas oil.

Major Sections:

  • Feed Preparation and Preheat System
  • Reactor System with Hydrotreating and Hydrocracking beds
  • Reactor Effluent Cooling and Separation System
  • Sour Water Section
  • Recycle Gas Compressor
  • Make-Up Hydrogen System
  • Fractionation Section

 

Major Operations for Trainee Practice:

  • Startup and Shutdown Operations
  • Normal Operations
  • Emergency Shutdown Operations
  • Troubleshooting Equipment, Instrument and Control Valve Malfunctions
  • Malfunction Recovery Actions

 

Simulation Features:

  • Effect on Cracking and Hydrotreating
    • Temperature
    • Hydrogen Partial Pressure
    • LHSV
    • Bed Aging
  • Detailed Reactor Conversion and Yield Calculations
    • Sulfur Conversion
    • Nitrogen Conversion
    • Hydrogen Conversion
    • Product Yields
  • Effect of Change in Feed S and N Content
  • Effect of Change in Catalyst Bed Activity
  • Effect of Nitrogen Poisoning on Cracking
  • Effect of Improper Flow Distribution in Reactor Beds
  • Cracking Reaction Runaway
  • Interlock / Safeguard System
  • Detailed Calculation of Products Properties
    • Complete ASTM Analysis of All Products
    • Reid Vapor Pressure of Light Naphtha
    • Flash Point of Heavy Naphtha, Kerosene and Gas Oil
    • Smoke Point of Kerosene
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