Podcast Beta
Questions and Answers
What is the primary function of glycol in the glycol dehydration process?
What happens to the glycol particles after they absorb water from the wet gas?
What is the purpose of the specialized boiler in the glycol dehydration process?
What is the boiling point of glycol?
Signup and view all the answers
What is the primary method of dehydrating natural gas using adsorption?
Signup and view all the answers
What is the purpose of the adsorption towers in solid-desiccant dehydration?
Signup and view all the answers
What is typically used as a solid desiccant in solid-desiccant dehydration?
Signup and view all the answers
Why is it possible to remove water from the glycol solution?
Signup and view all the answers
What is the primary function of a turbo-expander in an expander cycle liquefaction system?
Signup and view all the answers
What is the result of passing high-pressure natural gas through a turbo-expander?
Signup and view all the answers
What percentage of the incoming natural gas stream can be liquefied in an expander cycle?
Signup and view all the answers
What is the primary component of a mixed refrigerant cycle?
Signup and view all the answers
What is the purpose of partially flashing the liquid at each pressure reduction step in a mixed refrigerant cycle?
Signup and view all the answers
What is the significance of a separate refrigeration loop with propane as the refrigerant in a mixed refrigerant cycle?
Signup and view all the answers
What is the primary concern when acid gases are present in natural gas?
Signup and view all the answers
What is the capacity of a typical LNG tanker?
Signup and view all the answers
What is the purpose of an Acid Gas Removal Plant?
Signup and view all the answers
What is the result of mixing acid gases with water?
Signup and view all the answers
What is the estimated impact of an explosion on a LNG tanker?
Signup and view all the answers
What is the primary use of hydrogen sulfide in a refinery?
Signup and view all the answers
What is the minimum sulfur recovery required by regulations?
Signup and view all the answers
What is the purpose of the modified Claus process and the Shell Claus Off-Gas Treatment (SCOT) process?
Signup and view all the answers
What percentage of recovered sulfur is produced by the Claus process?
Signup and view all the answers
What is the purpose of the SCOT process?
Signup and view all the answers
Which of the following catalysts is more favourable in converting COS and CO2 to elemental sulphur?
Signup and view all the answers
What is the overall sulphur recovery efficiency of the SCOT process?
Signup and view all the answers
What is the purpose of acid gas treatment processes?
Signup and view all the answers
Which of the following compounds brings problems in Claus operations?
Signup and view all the answers
What is the reaction that occurs in the burner of the Claus process?
Signup and view all the answers
What is the type of absorption used in Amine Gas Treating?
Signup and view all the answers
What is the primary purpose of the RECTISOL process?
Signup and view all the answers
What is the effect of excess moisture in natural gas pipelines?
Signup and view all the answers
What is the purpose of a Gas Dehydration Plant?
Signup and view all the answers
What is the role of the solvent in the RECTISOL process?
Signup and view all the answers
What is the purpose of molecular sieves in the RECTISOL process?
Signup and view all the answers
What is the effect of pressure drop on the gas stream in natural gas pipelines?
Signup and view all the answers
What is the role of diethylene glycol (DEG) or triethylene glycol (TEG) in the Glycol Dehydration process?
Signup and view all the answers
Why is it necessary to remove water from natural gas pipelines?
Signup and view all the answers
Study Notes
Natural Gas Treatment
- Acid gas: a gas that can form acidic solutions when mixed with water, including sulfurous gases (Hydrogen Sulfide, H2S, and Carbonyl Sulfide, COS) and Carbon Dioxide (CO2)
- Properties of acid gases:
- Corrosive to pipelines, reactors, and tanks
- Toxic, flammable, and explosive
- Contaminants for the environment
- Hydrogen Sulfide (H2S):
- Poisonous
- Corrodes metallic equipment
- Carbon Dioxide (CO2):
- Reduces heating value
- Solidifies under high pressure and low temperature
Acid Gas Removal Plant
- Sour water stripper (SWS) produces a sour water stripper acid gas stream (SWSAG) containing Hydrogen Sulfide (H2S) and Ammonia (NH3)
- Sulfur Recovery Process:
- H2S commonly used as a refinery fuel
- Sulfur dioxide concentrations in flue gases must be within acceptable limits due to regulations
- Recovery process requires ~99% or more efficiency, achieved through a 2-stage process:
- Modified Claus Process
- Shell Claus Off-Gas Treatment (SCOT)
Modified Claus Process
- Most practical method for converting H2S to elemental sulfur
- First reported by Chance and Claus in 1885
- Process depends on H2S concentrations in natural gas
- 90-95% of recovered sulfur is produced by the Claus process
- Best suited for acid gas containing 50% or more H2S
Claus Sulfur Process
- Reaction: 2H2S + 3O2 → 2H2O + 2SO2
- Reaction: 2H2S + SO2 → 2H2O + 3S
- Catalysts: Activated aluminum(III) or titanium(IV) oxide
- Elemental sulfur is used as fertilizer and pesticide
Carbon-Sulfur Compounds
- Carbonyl sulfide (COS) and carbon disulfide (CS2) cause problems in Claus operations
- These compounds cannot be completely converted to sulfur compounds and CO2
- Formed during combustion through the reaction of HCs and CO2
- Alumina catalyst is more favorable in converting COS and CO2 to elemental sulfur compared to bromide catalyst
Shell Claus Off-Gas Treatment (SCOT) Process
- Designed to remove sulfur compounds from Claus tail gas to comply with air emission regulations
- Overall sulfur recovery efficiency of 99.9%
- SCOT units are designed for minimum pressure drop to be easily added to existing Claus units
Natural Gas Treatment Processes
- Purpose: to obtain sweet, dry natural gas by removing acid gases and reducing water vapor
- Amine Gas Treating: uses solvents like MDEA (Methyldiethanolamine), DEA (Diethanolamine), and MEA (Monoethanolamine)
- RECTISOL Process: physically absorbs undesired compounds like CO2, H2S, COS, and other sulfur compounds from the gas using a solvent
- Chemical Absorption: uses chemical reactions to absorb acid gases
- Physical Adsorption: uses solid adsorbents with high surface areas, like molecular sieves, to adsorb acid gases
Water Removal
- Purpose: to reduce corrosion problems and prevent hydrate formation
- In 1,000 cubic meters of gas, there can be 10-100 liters of water
- Excess moisture in natural gas pipelines can cause:
- Corrosion problems
- Hydrate formation
- Blockages
- Reduced heating value
- Liquid slugs can damage compressors
Gas Dehydration Plant
- Uses glycol dehydration to remove water vapor from the gas stream
- Glycol: a liquid desiccant that absorbs water vapor from the gas stream
- Process: glycol solution is contacted with wet gas, absorbs water, and is then regenerated through heating
Solid Dessicant Dehydration
- Uses solid desiccants like activated alumina or granular silica gel to adsorb water vapor from the gas stream
- Process: wet gas is passed through adsorption towers, and water is retained on the surface of the desiccant particles
Liquefaction Systems
- Expander Cycle Liquefaction System:
- Uses a turbo-expander to chill the incoming natural gas stream and liquefy a small portion of the stream
- Generally, no more than 10% of the incoming natural gas stream can be liquefied
- Mixed Refrigerant Cycle:
- Uses a mixture of refrigerants (such as propane, ethane, methane, and nitrogen) within a single refrigeration loop
- Produces a series of refrigeration loops at different temperatures
- Can be used to pre-cool the gas feed before it is introduced into the mixed refrigerant system
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the properties and effects of acid gases, including sulfurous gases and carbon dioxide, in natural gas treatment. Learn about their corrosive and toxic nature.
