Kesler Engineering, Inc.

Fired Heater Sentinel

Introduction to KEI• KEI Established 1979 by Michael Kesler

– Co-Author of Lee-Kesler Correlation for Thermodynamic Properties of Mixtures

– Developed First Industry General Process Simulator (MW Kellogg -1958)

• Main Business– Process Engineering– Software Products

• Sophisticated highly focused models that work on-line with PI and ProcessBook

• KEI is Partly Owned by OSI Software

Fired Heater Sentinel - Problem Statement

• Correct operation of fired heaters has a large impact on the profitability and safety of plants

• Information required for proper operation is obtainable from raw process data only with the aid of detailed models designed for real-time operations

Fired Heater Sentinel - Coking and Scaling

• Process Fluids Are Heated to Thermal Stability Limits to Improve Product Quality and Unit Throughput.

• Exceeding Thermal Stability Limits Results in Coke Laydown (or Scaling). This is irreversible during operations.

• Coking and Scaling Result in High Tube Metal Temperature. Heater Duty Must Be Reduced to Eliminate Risk of Tube Rupture.

Bulk Temperature:760 F

Film Temperature:806 F

Tube Wall Temperature:

824 F

Clean Tube

Bulk Temperature:760 F

Film Temperature:806 F

Tube Wall Temperature:

1,100 F

Coked Tube

Fired Heater Sentinel - Economics

• Over-All Process and Fired Side Efficiency Calculations– Process Side Calculations Much More Accurate– Requires Flash and Composition (obtained from

reconstituted product specs and flows)

• Immediate Notification of Abnormal Situation– Sensor Malfunction– Inefficient Operation– Equipment Failure

Fired Heater Sentinel - Economics

• Calculation of Lost $ Due to Excess Air

• Calculation of Lost $ Due to Heater Flooding/Bogging

• Calculation of Lost $ Due to Capacity Reduction From Coking/Fouling

• Advice on Which Heater to Clean and When

Fired Heater Sentinel - Heater Health

• Heater Health Baseline Obtained From Historical Data

• Pass by Pass Calculation and Monitoring of:– Duty– Heat Flux– Mean Metal Temperature– Convection and Radiant Section Duty– Coking Thickness

Fired Heater Sentinel - Heater Health

• Indication of Coking Events

• Monitoring of Convection Section After-Burning

• Convection Section Fouling– Long Term Ratio of Convection Section Heat

Input to Total Heat Input– Draft Limit at Arch, Stack Damper Open,

Firing Within Historical Limits

Fired Heater Sentinel - Safety

• Key is Calculation of Convection and Radiant Section Duties– Requires Process Flash and Composition (obtained

from reconstituted product specs and flows)

• Abnormally High Individual Pass Convection Section Duty Suggests Convection Section Seam Split

• Increase in COT (Duty Ratios Unchanged), Suggests Radiant Section Leak

Fired Heater Sentinel - Implementation

• Easy to Use Setup Wizard– Guides You Through Configuration and

Selection of PI Tags– Makes Intelligent Assumptions When Data or

Instrumentation Is Not Available– Detailed Knowledge of Heater Geometry and

Burner Characteristics is Not Required

• Intuitive - Little or No Training Required

Models: COM Objects

• Use the same model for off-line what-if analysis– Excel spreadsheets, VB applications

• Open equation model format permits flexible case studies– “How much fuel would be required if stack

temperature was 550ºF?”

• On-line case studies

Fired Heater Sentinel - Value• A 2% Increase In Efficiency For a 200 MM Btu/hr

Heater Results in a Savings of US$70,000/yr• If Fired Heater Is the Plant Constraint, 1%

Increase in Heat Transfer (by Preventing Coking) Will Increase Throughput by 1%– Up to US$1 Million/yr in Refining Margins for a

100,000 BPD Refinery