1. Natural Gas Processing I Chapter 2 In-feed System
PTRT 1317
Natural Gas Processing I
Chapter 2
In-feed System

2. Gas Processing Remove oil and condensates Remove water
Recover Natural Gas Liquids
Remove Sulfur and Carbon Dioxide
Remove impurities
Mercury
Oxygen
BTEX (Benzene, Toluene, Ethyl benzene, Xylene)

3. Gas Processing Plant

4. Feed Gas Receiving System
Initial treating unit in the gas plant
Feed gas receiving system
Condensate stabilization
Condensate
Light hydrocarbon liquid obtained by condensation of hydrocarbon vapors
Varying proportions of butanes, pentanes
Little or no methane or ethane
Retains light components that are DISSOLVED in the hydrocarbon liquids
Methane
Ethane
Propane

5. Feed Gas Reception (In-feed) System
Feed gas can contain
Hydrocarbon liquids
Aqueous liquids
Hydrocarbon and acidic gases
Entrained solids
Chemicals
Corrosion control
Hydrate inhibitors
Compressor lubrication
Reception system
Pig Receiver/Launcher
Slug catchers
Feed gas heaters
Separators
Filters

6. Typical In-feed System
1000 psi gas
Typical In-feed System
100 psi gas
100 psi water
100 psi condensate
Every couple weeks
Pig receiver used

7. Slug Catcher Velocity reduction causes liquids and solids to drop out
Separated gases are heated to prevent hydrate formation during pressure reduction
Separated liquids are filtered, heated and undergo a pressure drop before entering three-phase separator

8. This PFD describes the “most critical and important” in an Amine Treating Plant. The Inlet Gas separation and filtration equipment.
When this equipment is sized properly and maintained properly, an Amine Plant’s overall operation will be improved. Foaming in an Amine Plant is the most common problem. Proper Inlet Gas separation and filtration equipment can eliminate most of this problem.

9. Slug Catcher
Free Liquid is captured in the Slug Catcher. It is also used to capture the high volumes of liquid that arrive when pigging the pipeline.
Inlet Gas From Gathering System
Inlet Gas Out of Slug Catcher going to the Amine Plant

10. Slug Catchers Separates liquid slugs formed in pipelines
Liquid waves grow large enough to bridge pipe diameter
Liquid accumulated in low spots in pipeline
Increased feed flow results in excess liquids
Pigging pushes out the entire accumulated inventory of liquids in the low spots of the pipeline
Maximum size of the slugs must be considered in design
Holds several weeks of accumulation
Temperatures, topography, gas composition
100 vol% hydrocarbons to 80 vol% water

12. Horizontal
Vertical
Pipe-fitting-type

13. This PFD describes the “most critical and important” in an Amine Treating Plant. The Inlet Gas separation and filtration equipment.
When this equipment is sized properly and maintained properly, an Amine Plant’s overall operation will be improved. Foaming in an Amine Plant is the most common problem. Proper Inlet Gas separation and filtration equipment can eliminate most of this problem.

14. Inlet Separator Inlet Gas from Inlet Separator to Inlet Gas Filter
Inlet Gas from Slug Catcher
Inlet Separator
Remove additional free liquids from the gas entering the Plant from the Slug Catcher.

15. This PFD describes the “most critical and important” in an Amine Treating Plant. The Inlet Gas separation and filtration equipment.
When this equipment is sized properly and maintained properly, an Amine Plant’s overall operation will be improved. Foaming in an Amine Plant is the most common problem. Proper Inlet Gas separation and filtration equipment can eliminate most of this problem.

16. Inlet Filter
Purpose: To remove small particles, liquid, and aerosols from the Inlet Gas.

17. Inlet Filter Inlet Gas from Inlet Separator to Inlet Filter
Purpose: To remove small particles and aerosols from the Inlet Gas. Uses filter elements that the Inlet Gas flow through and the particles are captured in the filter elements. The aerosols and small liquid particles will also coalesce on the filter elements and will drain into the bottom sump of the Inlet Filter. Inlet Gas Filtration is the most critical equipment in reducing amine foaming problems.
Inlet Gas from Inlet Separator to Inlet Filter
Inlet Gas out of Inlet Filter to Amine Contactor Feed Heater (exchanger)

18. Equipment Selection and Design
Pressure capacity of pig receiver and slug catcher must be same pressure capacity as pipeline
High Integrity Pressure Protection System (HIPPS) valves allow for lower downstream pressures to be used by difficult regulatory practice to follow
API 521, ASME Code Case 2211 Section VIII
Incoming slug size determined using GPSA Engineering Data Book – Section 17

19. Design Basis and Specifications
Hydrocarbon content of feed gas varies
Plant process depends on composition so engineer bounds the plant design by three cases
Lean feed
Average feed
Rich feed
Gas receiving system usually defined by the rich feed in winter conditions
Lean feed defines the turndown ratio of the plant design
Turndown ratio = maximum output/minimum controlled output
Condensate Product Specification (see text)

20. Typical Gas Feeds

21. Pig Receiver
Needed unless pipeline transfers only dry gas and hydrocarbon liquids
Periodically removes accumulations of liquids at low spots in the pipeline
Prevents corrosion
Improves efficiency
Reduces pressure losses
Limits maximum slug size
Slug size determined by temperature, topography, pipeline length, and feed gas composition

23. Gas and Liquid Heaters
Feed gas reception use heaters to raise the temp of gas and liquid separated by slug catcher
Prevent hydrate formation
Prevent retrograde condensate formation
Maintain temp above minimum for downstream equipment
Raise temp to requirement of gas-treating unit (95 ⁰F)
High CO2 concentrations cause a kinetic reaction and generate heat
Design of the heater must generate the require temps at low CO2 concentrations

24. Typical In-feed System
1000 psi gas
Typical In-feed System
100 psi gas
100 psi water
100 psi condensate
Every couple weeks
Pig receiver used