Removal of H 2 S From Coal and Crude Oil. Christina Fontanos Bethany Levering William Pfeiffer Ryan Smith

Transcription

1 Removal of H 2 S From Coal and Crude Oil Christina Fontanos Bethany Levering William Pfeiffer Ryan Smith

2 What is Hydrogen Sulfide? Chemical Formula: H2S Colorless gas with rotten egg odor It can be produced by the bacterial breakdown of organic matter, often in water, as free oxygen must be absent.

3 Physical Properties Molar Mass: 34.8 g/mol Density: g/l Melting Point: 191 K Boiling Point: 213 K Flash Point: K Low boiling point low density cause H2S to move into the vapor phase and stays in the head space of crude oil containers. The low flash point illustrates hydrogen sulfide s extreme flammability and explosiveness.

4 Why do Chemical Engineers Care? Naturally occurring in many crude oils Also produced in oil refining processes by the degradation of the sulfur containing compounds in crude oil. Heavily regulated because of its high toxicity, so removal and containment is crucial in petroleum industry.

5 Hydrogen Sulfide: The Silent Killer Highly Toxic Concentrations of ppm are lethal. Cardiovascular and respiratory failure. Improper handing and storage conditions can increase H 2 S concentrations in containers. OSHA Standards Concentrations may not exceed 20ppm in general industry practices

6 Foul odor Environmental Concerns: Treecapitation Rotten eggs Greenhouse Gas Acid rain

7 Operational Concerns: Machines Break While Tripping on Acid Flare Gas Sulfur Oxides are produced when H 2 S contaminated fuels are flared. Liquefied Petroleum Gas (LPG) Corrosion in copper fuel systems. Corrosion in ferrous storage vessels Refined Fuels Corrosion in copper systems Treatment of refined fuels to account for H 2 S alter the viscosity of the fuel. Gasoline sulfur content limited to 80ppm per gallon

8 Operational Concerns: Machines Break While Tripping on Acid Crude Oil and Heavy Fuel H 2 S contamination results from thermal cracking of high molecular weight Sulfur compounds. H 2 S scavenger reside can damage equipment. Asphalt High storage temperature promotes generation of H 2 S by thermal cracking. Contains H 2 S concentrations of up to 10,000ppm High vapor:liquid partition coefficient. Most H 2 S concentrates in vapor phase. Difficult to treat

9 Methods for H 2 S Removal from Crude Oil: Do Away With the Undesirables Crude oil contains 0-3% sulfur Sources of S in crude oil: thiols, thiophenes, sulfides, disulfides H 2 S gas must be removed from crude oil before transport

10 Methods for H 2 S Removal from Crude Oil: Flaring and Sour Gas Collection Light hydrocarbons and impurities captured in VRUs H 2 S in the headspace of tanks or wells is captured and flared off in emergencies The SO 2 product is a greenhouse gas still limited by the EPA

11 Methods for H 2 S Removal from Crude Oil: Hydrodesulfurization (HDS) Must be done before hydrocarbon cracking; S will poison the cracking catalysts High T/high P PBRs with transition metal sulfide catalysts on alumina supports (Co/Mo, RuS 2 ) Sulfur compounds are converted to H 2 S which are removed in subsequent units ages/pic4uhm7n77.jpg

12 Methods for H 2 S Removal from Crude The oil can be stripped of H 2 S using natural gas Oil: Gas Stripping Oil is passed down through a contact tower over trays while the natural gas flows up through the column

13 Methods for H 2 S Removal from Crude Oil: Amine Treatment Amine Treatment Diethanolamine (DEA) Monoethanolamine (MEA) Methyldiethanolamin e (MDEA) Diisopropanolamine (DIPA) Diglycolamine (DGA) -treating.png RNH 2 + H 2 S RNH SH +

14 Removing H 2 S from Coal Major Uses for Coal Direct Burning Power Plants Synthetic Gas Gasoline Diesel Plastics

15 Removing H 2 S from Coal Direct Burning Scrubbers Remove SO 2 Spray steam and cation containing material Limestone (Ca 2+ ) Magnesium oxide (Mg 2+ ) Forms salt

16 Removing H 2 S from Coal Coal is also converted to synthetic gas (syngas) Add Water and Air to Coal Syngas - Main Components CH 4 CO CO 2 H 2 S H 2 H 2 O

17 Removing H 2 S from Coal Must remove H 2 S before using the syngas Physical Removal Absorb Chemical Removal Reaction

18 Removing H 2 S from Coal Physical Removal Physical Sorbent Graphite Activated Carbon Fibers Physical Solvent NMP Propylene Carbonate Chemical Removal Chemical Sorbents Dolomite Limestone Sample_of_propylene_carbonate.jpg/200px- Sample_of_propylene_carbonate.jpg

19 References Abbasian, Javad, and Amir Rehmat. "H 2 S REMOVAL FROM FUEL GAS DURING COAL GASIFICATION." Argonne National Laboratory. Web. "Sulfur Dioxide Scrubbers." Duke Energy. Web. Li, Huixing. "SELECTIVE CATALYTIC OXIDATION OF HYDROGEN SULFIDE FROM SYNGAS." University of Pittsburgh. Web. Burr, Barry, and Lili Lyddon. "A COMPARISON OF PHYSICAL SOLVENTS FOR ACID GAS REMOVAL." Bryan Research & Engineering. Web.