Reconciling Mass And Energy Balances In An Ethylene Complex

Reconciling Mass and Energy Balances in an Ethylene Complex Patrick Truesdale Senior Consultant Industry Solution Group Emerson Process Management November 11, 2009 Nashville, TN

Presentation Objectives
Background and Business Challenge
Business Opportunities
How to Achieve?
Case Examples
Summary

Introduction
Accurate measurements are an essential part of a refinery or petrochemical complex
Measurement technology has dramatically improved in past 25 years
Environmental and governmental regulations have increased necessitating accurate measurements
Changing demographics
Benefits can be significant!

Ethylene Plants: Configuration and Complexity Ref: T. Ren, University of Utrecht and BASF 2000

Ethylene Plants: Estimated Capacities – 1 Jan. 2009 Ref: OGJ 30 July 2009

Ethylene Plants: Global Distribution and Age In 1980’s Plants were typically ca 300kta Now Mega Crackers > 1,000kta Predominantly Greenfield Predominantly Brownfield

Hydrocarbon/Measurement Timeline

Challenges to achieve benefits
Measurement systems for Mass are relatively new for old Plants
Belief that errors are mostly due to fuel gas/oil production/consumption over/under statement (ie. Little need to coordinate energy usage with losses)
Prices have escalated rapidly in past few years; currently many plants are spending significant capital to met new specs, increase capacity, regulatory compliance, process cheaper feed stocks. Staff is stretched.
Business function and organization requires addressing NOT just software tools; but the new operator and engineer in plant.

Typical Plant Demographics Operations Engineering Maintenance Small decline due to automation Downsized by 70 - 90% Downsized by 5% per year for past 10 years. Typical Plant w/ 3,308 workers
Operators now responsible
for optimization efforts
75+% experienced operators
slated to retire by 2015
Skilled labor pool falling
0-20 21-34 35-44 45-54 55-65 65+ Age

Meet the New Engineers and Operators! We may dress funny but we’re computer geeks!

Key Performance Indexes
Asset Utilization
Plant Reliability
Operating Efficiency
Margin
Energy Efficiency
Loss Opportunities
Environmental
Safety

Where are losses? Why Important? Open Inventory + Receipts – Shipments – Closing Inventory = Gain/Loss Gain/Loss = Accountable + Unaccountable Leaks Theft Flare Coke Fuel Produced Fuel Consumed

Energy Efficiency

Step 1: Define Process Boundaries C2 Hydrogenation Cold Box C3 Hydrogenation Cracked Gas Compressor Quench Tower Cracking Furnaces Hydrogen 1%-9% Methane 6%-28% (fuel) Ethylene 23%-76% Ethane 3%-20% (recycle) Propylene 3%-16% Propane 2%-10% C4s 2%-9% Gasoline <1%-35% Steam & Waste Heat Steam Steam Feeds (60%) Ethane (C2) Propane (C3) Butane (C4) Naphtha (C5 – C12) Gas Oil (C10 – C15) Fuel Gas Drying and Chilling Ethylene and Propylene Refrigeration Systems Steam (40%) Quench Water Circuit Oil / Tar Fractionator Fuel Oil Tar C2 Splitter Depropanizer C3 Splitter Debutanizer Deethanizer Demethanizer 800-900 ° C 1.5 bar 350 ° C 1.5 bar 30 ° C 1.5 bar 10 ° C 1.5 bar -100 ° C 32 bar 20 ° C 5 bar 50 ° C 2 bar -10 ° C 30 bar 10 ° C 10 bar -10 ° C 30 bar 75 ° C 30 bar 70 ° C 8 bar 90 ° C 5 bar 45 ° C 5 bar 45 ° C 16 bar 35 ° C 16 bar -20 ° C 20 bar -30 ° C 20 bar -6 ° C 20 bar 80 ° C 1.5 bar Fired Heater Distillation Cryogenic Distillation Hydrogenation Reactor Turbo Compressor

Shore Ship Consumers Raw Material Production & Supply Ethylene Complex Load Port Logistics Unload Port Ship Shore Shore Ship Transportation Loss Load Port Transportation Loss Shore Unload Port Ship $ “The Cash Register” Step 2: Identify Custody Transfer Boundaries? BOL BOL

Step 3: Design Mass and Energy Balances Receipts Shipments Intercompany Inventories Tank-to-tank transfers Unit-to-tank transfers Process Nodes Tank-to-unit transfers Losses Consumption

Step 4: Survey Measurement Systems
With poor instrumentation and procedures:
= 1.5 - 2.5% Mass losses
With average instrumentation and procedures:
= 0.7 – 1.5% Mass losses
With good instrumentation and procedures:
= < 0.5% Mass losses
Pacesetter = <0.2%
Pacesetter look at Solomon KPI;
Others such Shell Global Services, Juran, etc.

Select Technology Required Pressure Drop Accuracy Low Maintenance Slurry Flows Viscosity Independent Flow meter Type Non- Conductive Fluids Non- Intrusive Turbine Positive Displacement Coriolis Magmeter Differential Pressure Vortex Good Marginal Poor Ultrasonic

Coriolis Measurement Capabilities
Direct MASS flow measurement
Rangeability: (100:1 non custody), (20:1 custody)
Accuracy (@20:1 turndown)
Mass Flow Rate: ± 0.10 %
Volume Flow Rate: ± 0.13%
Unaffected by most fluid variations
P,T,density,viscosity, conductivity
Velocity profile independent
Bi-Directional
Multi-variable outputs available
Qm, Qv, T, Density, % Solids, Viscosity

Tank Gauge Measurement Capabilities 1 API ± 3/16" (4 mm) 2 PTB, Germany 3 NMi, Netherlands 4 OIML, International 5 TankRadar

Flow meters or ATG’s ?
Influence of batch size:
At large transfer volumes ATG’s have potential to have better performance. Systematic error on a meter will have a large influence.
At small transfer volumes meters have potential to have better performance. Resolution may not be sufficient on an ATG.

Do errors always get even out? Think again! NO: Statistical sum of several measurement errors equals: Square Root of the sum of Square of the errors When adding several errors, sum can not be zero!

Step 6: Develop Mass & Energy Balance Models
Validation, Detection and Correction: Gross and Bias Errors
Reconciles for Random Errors
Mass and Volume balancing
Flows, inventories, material transfers
Component balancing (Simple and Multi-phase)
Flows, inventories
Energy balancing
Enthalpy, power, heat exchanger balance, steam
Simultaneous Solution of all equations

Example Heat Balance Envelope 100 Kg 9.242 MJ 91423.7 J/Kg 100 Kg 1.068 MJ 10683.6 J/Kg 100 Kg 4.217 MJ 42170 J/Kg 100 Kg 12.291 MJ 122.9 KJ/Kg 100 Kg 3.871 MJ 38706 J/Kg 100 Kg 11.944 MJ 11944.6 J/Kg

Step 5: Define Business Process Period End Cutoff Data Gross Error Detection and Diagnostics Trial Balancing Resolution or Reconciliation Checking Modifications Adjustments Complex Configuration Models Measurements Movements Lab Data Meter Tickets Surveyor Documents Tank Inventories Utilities Results Generation Manual Input Automatic Data Collection Reconciled Balances, Yield, Loss and Inventory Reporting Production Management Data Base Integrate with Other Systems (SCM, SAP, LP, etc)

Step 7: Identify KPI Reporting

KPI Dashboard

Step 8: Implement Continuous Improvement
Where did it happen?
Models
Process
Data Quality
Time (Weeks)
Capacity
Utilization
Production rate
Quality
Energy
Yield
Margin
Reliability
Environmental
What went wrong?? What went right?? Before (Monthly) Plan/Schedule 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Actual Operation After (Daily)

Get Benefits: Operational Excellence Impact Up to 7.9% Operational Improvement by Impacting… +3% +2.4% -1.3% -1% -0.2%

Measurement Losses: What is it worth? Assume 0.2% Loss Reduction 93% 1150$/t 500$/t

Measurement Losses: What is it worth? Assume 0.2% Loss Reduction
Product
Capacity
Price
Margin
Utilization factor
Amount
Ethylene
900 kMT/yr
1 150 $/t
500 $/t
93%
47 774 $/hr
Propylene
450 kMT/yr
1 150 $/t
500 $/t
93%
23 887 $/hr
$71 661
0.2%
$143/hr
1 hr
1 yr
$1 255 500

Case 1: Losses Analysis (%Mass) Range
Custody transfer (receipt and shipments)
Fuel and H2 consumption (understated, not real losses)
Flare, in effluent, evaporation, stack loss, vents and leaks, coke
0.35 to 0.55 0.85 to 1.05 0.45 to 0.65 TOTAL 1.65 to 2.25 Estimate 0.45 0.95 0.55 1.95

Case 1: Benefit Calculation
Estimate loss = 1.95%
Custody Transfer Loss = 0.45%
Flare, Coke, Other Loss = 0.55%
Apparent (understated fuel/H2 consumption) = 0.95%
Improvement
Achievable Goal = 0.4%
Delta = (0.45%+0.55%-0.4% = 0.6%)
0.6% x 12MM T/yr x 210US$/T = $15,120,000/yr
Supply chain optimization
0.25 $/T x 12MM T/yr = $3,000,000/yr

Case 2: Measurement Errors vs Economic Losses Control Variable Objective Function (e.g. Profit) Operating Region Deviations are often corrected with high-cost sub-optimum correction ! Potential lost profit from inaccurate measurements.

Trading Benefits A Gulf Coast refiner switched a cargo of crude with just one-and-a-half hours of supply left in inventory . Without very close coordination between trading and operations, the $8 million profit opportunity would have been lost. Hydrocarbon Processing

Trading Example Trader Gulf Coast Complex Okay, if you can agree with the shipper to deliver 8 hours earlier, then we will have a four hour safety margin and the trade is agreed. Hold on while we check:: - Current inventory - Maintenance Plan - Agreed Receipts and Shipments and rerun the schedule to check the impact on stocks and cash flow. Delivery 8 hours earlier is agreed. We make $3,000,000 and we extend our credit line by 3 days. GREAT, is there anything I can do to help with a backup strategy? We have an excellent opportunity to purchase a cargo of feed stock. Can we take it?

Key Takeaways
Ethylene plants have large incentives to reduce losses and optimize energy usage. These two KPI are interrelated.
With the sharp increase in feedstock prices and accessibility, the industry has a compelling need for improving the timeliness and accuracy of production data.
Specifications and governmental regulations continue to tighten - accurate measurements are essential to mitigate compliance
Since late 1950 there has been and continues to be significant technological improvement in measurement systems
Smart Instruments and Wireless technology opens additional benefits for the future!
Improved accuracy of Production Data (Mass and Energy Balance Reconciliation) impacts many KPI’s . The solution approach, therefore, “ is Green ” (provides significant benefits).

Wrap-up
Questions? Comments?
Where to get more information?
White Papers
Presentations
Specific requirements?
Contact:
Patrick Truesdale ( [email_address] )

Thank You

http://www.emersonprocessxperts.com	367
http://www.slideshare.net	12
http://prsync.com	9
http://cursos.itesm.mx	2
http://translate.googleusercontent.com	1
http://www.techgig.com	1

Reconciling Mass And Energy Balances In An Ethylene Complex

by Jim Cahill on Nov 19, 2009

Accessibility

Categories

Tags

Upload Details

Usage Rights

6 Embeds 392

Statistics

Reconciling Mass And Energy Balances In An Ethylene Complex — Presentation Transcript