PROCESS ECONOMICS PROGRAM

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1 PROCESS ECONOMICS PROGRAM SRI INTERNATIONAL Menlo Park, California Abstract Process Economics Program Report No. 135 NATURAL GAS LIQUIES Natural gas liquids (NGL) are the C2-k liquefied hydrocarbons which are recovered above ground in natural gas field facilities or in gas processirg plants. The report concerns the technology and econanics of NGL recovery in gas processing plants by the following three most important processes in commercial use today: Expander Cascade refrigeration Refrigerated absorption. The principal products are ethane, propane, isobutane, n-butane, and C5+ natural gasoline. Capital investment and production costs have been calculated for the expander and cascade refrigeration processes at two natural gas liquids contents (2.32 and 6.26 gal/l,000 scf) and two levels of ethane recoveries (86 and 50%), and for the refrigerated absorption process at the same two natural gas liquids contents but only 50% ethane recoveries. The study shows that, for an equivalent ethane recovery, the expander process has the lowest energy consumption as well as the lowest investment and product value (production cost +25%/yr ROI), followed by the cascade refrigeration and refrigerated absorption processes, in that order. PEP '78 JJLM

2 Report No. 135 NATURAL GAS LIQUIDS JAMES J. L. MA contributions by : CHING-SHIEN WU c 1 A private report by the October 1979 PROCESS ECONOMICS PROGRAM Menlo Park, California 94025

3 For detailed marketing data and information, the reader is referred to one of the SRI programs specializing in marketing research. The CHEMICAL ECONOMICS HANDBOOK Program covers most major chemicals and chemical products produced in the United States and the WORLD PETRCCHEMICALS Program covers major hydrocarbons and their derivatives on a worldwide basis. In addition, the SRI DIRECTORY OF CHEMICAL PRODUCERS services provide detailed lists of chemical producers by company, product, and plant for the United States and Western Europe. ii

4 CONTENTS INTRODUCTION... 1 SUMMARY... General Aspects... Economic Aspects... Technical Aspects... Expander... Cascade Refrigeration... Refrigerated Absorption INDUSTRY STATUS NGL RECOVERY - GENERAL PROCESS BACKGROUND... Natural Gas Composition... Thermodynamics and Phase Equilibrium... Process Types.... Compression... Adsorption... Ambient Temperature Absorption... Refrigerated Absorption... Straight Refrigeration... Joule-Thomson Expansion... Expander... Gas Treating... NGL BY THE EXPANDER PROCESS... Review of Process... Process Description... Process Discussion... Cost Estimates... Capital Costs.... Production Costs... NGL BY THE CASCADE REFRIGERATION PROCESS... Review of Process... Process Description... Process Discussion... Cost Estimates... Capital Costs... Production Costs

5 CONTENTS 7 NGL BY THE REFRIGERATED ABSORPTION PROCESS Review of Process Process Description 152 Process Discussion Cost Estimates Capital Costs Production Costs APPENDIX A DESIGN AND COST BASIS APPENDIX B SPECIFICATIONS CITEDREFERENCES PATENTREFERENCES BY COMPANY

6 ILLUSTRATIONS 3.1 Natural Gas Liquids Schematic Diagram of Gas Recovery and Gas Processing NGL Recovery Vapor-Liquid Equilibriura for a Multicomponent Mixture NGL Recovery The Effect of Critical Point Location on Liquid-Gas Ratio NGL by the Expander Process A Schematic Diagram of Expander Thermodynamics NGL by the Expander Process Flow Diagram NGL by the Expander Process Effect of Plant Capacity on Total Fixed Capital Investment , NGL by the Expander Process Effect of Thermal Value on Average Products Value NGL by the Expander Process Effect of Operating Level and Plant Capacity on Production Cost for Cases A and B NGL Recovery by the Expander Process Effect of Operating Level and Plant Capacity on Production Cost for Cases C and D NGL by the Cascade Refrigeration Process Process Flow Schemes NGL by the Cascade Refrigeration Process Flow Diagram NGL by the Cascade Refrigeration Process Effect of Plant Capacity on Total Fixed Capital Investment NGL by the Cascade Refrigeration Process Effect of Thermal Value on Average Products Value NGL by the Cascade Refrigeration Process Effect of Operating Level and Plant Capacity on Production Cost NGL by the Cascade Refrigeration Process Effect of Operating Level and Plant Capacity on Production Cost Xi

7 ILLUSTRATIONS Flow Diagram Effect of Plant Capacity on Total Fixed Capital Investment Effect of Thermal Value on Average Products Value Effect of Operating Level and Plant Capacity on Production Cost xii

8 TABLES NGL Recovery Processes Summary of Compressor Power Requirements and Fuel Consumption Natural Gas Liquids U.S. Gas Liquids Supply and Consumption NGL Recovery Processes Summary of Economics....., Natural Gas Liquids World Gas Processing Plant Capacities and NGL Production Natural Gas Liquids Major Gas Processing States in United States Natural Gas Liquids Major U.S. NGL Producers and Plant Capacities Natural Gas Liquids Processes and Plant Capacities in United States Natural Gas Liquids World Natural Gas Production Trends and New Gas Processing Projects Natural Gas Liquids World Estimated Major Natural Gas Reserves NGL Recovery - General Process Background Examples of Natural Gas Composition NGL Recovery - General Process Background Operating Ranges of the Soave-Redlich-Kwong Correlation NGL Recovery - General Process Background Summary of Patents--Gas Treating and Drying NGL Recovery by the Expander Process Summary of Patents NGL by the Expander Process Design Bases NGL by the Expander Process, Rich Gas, 86% Ethane Recovery Stream Flows Xiii

9 TABLES NGL by the Expander Process, Rich Gas, 50% Ethane Recovery Stream Flows... NGL by the Expander Process, Lean Gas, 85% Ethane Recovery Stream Flows... NGL by the Expander Process, Lean Gas, 50% Ethane Recovery Stream Flows... NGL by the Expander Process Waste Streams NGL by the Expander Process Major Equipment and Utilities Summary NGL by the Expander Process Compressor Power Requirement and Fuel Consumption..... NGL by the Expander Process Residue Gas Composition and Heating Value NGL by the Expander Process, Rich Gas, 86% Ethane Recovery Total Capital Investment NGL by the Expander Process, Rich Gas, 50% Ethane Recovery. Total Capital Investment NGL by the Expander Process, Lean Gas, 85% Ethane Recovery Total Capital Investment NGL by the Expander Process, Lean Gas, 50% Ethane Recovery Total Capital Investment NGL by the Expander Process, Rich Gas, 86% Ethane Recovery Production Costs NGL by the Expander Process, Rich Gas, 50% Ethane Recovery Production Costs NGL by the Expander Process, Lean Gas, 85% Ethane Recovery Production Costs xiv

10 TABLES 5.18 NGL by the Expander Process, Lean Gas, 50% Ethane Recovery Production Costs NGL by the Expander Process Fractionation Investment and Production Costs NGL by the Expander Process Summary of Production Costs in Metric Units NGL by the Cascade Refrigeration Process Summary of Patents NGL by the Cascade Refrigeration Process, Rich Gas, 86% Ethane Recovery Stream Flows NGL by the Cascade Refrigeration Process, Rich Gas, 50% Ethane Recovery Stream Flows NGL by the Cascade Refrigeration Process, Lean Gas, 85% Ethane Recovery Stream Flows NGL by the Cascade Refrigeration Process, Lean Gas, 50% Ethane Recovery Stream Flows NGL by the Cascade Refrigeration Process Major Equipment and Utilities Summary NGL by the Cascade Refrigeration Process Compressor Power Requirement and Fuel Consumption NGL by the Cascade Refrigeration Process Residue Gas Composition and Heating Value NGL by the Cascade Refrigeration Process, Rich Gas, 86% Ethane Recovery Total Capital Investment NGL by the Cascade Refrigeration Process, Rich Gas, 50% Ethane Recovery Total Capital Investment NGL by the Cascade Refrigeration Process, Lean Gas, 85% Ethane Recovery Total Capital Investment xv

11 TABLES 6.12 NGL by the Cascade Refrigeration Process, Lean Gas, 50% Ethane Recovery Total Capital Investment * NGL by the Cascade Refrigeration Process, Rich Gas, 86X; Ethane Recovery Total Capital Investment NGL by the Cascade Refrigeration Process, Rich Gas, 50% Ethane Recovery Total Capital Investment NGL by the Cascade Refrigeration Process, Lean Gas, 85% Ethane Recovery Production Costs NGL by the Cascade Refrigeration Process, Lean Gas, 50% Ethane Recovery Production Costs NGL by the Cascade Refrigeration Process Fractionation Investment and Production Costs NGL by the Cascade Refrigeration Process Summary of Production Costs in Metric Units NGL Recovery by the Refrigerated Absorption Process Design Bases Rich Gas, 50% Ethane Recovery Stream Flows , Lean Gas, 50% Ethane Recovery Stream Flows Major Equipment and Utilities Summary Compressor Power Requirement and Fuel Consumption Residue Gas Composition and Heating Value , Rich Gas, 50% Ethane Recovery Total Capital Investment xvi

12 TABLES : B.l -B.2 B.3 B.4, Lean Gas, 50% Ethane Recovery Total Capital Investment , Rich Gas, 50% Ethane Recovery Production Costs , , Lean Gas, 50% Ethane Recovery Production Costs Fractionation Investment and Production Costs Summary of Production Costs in Metric Units..... A Comparison of Product Values and Sales Incomes Typical Sales Gas Specifications Ethane Criteria Propane, Butane, and Propane-Butane Mixture Specifications Natural Gasoline Specifications xvii