6 (part 1)

Question 1

5 examples of impurities

Answer 1

• water
• sulfur species
• mercury
• NORM
• oxygen

Question 2

Most gas produced contains water, which must be removed. Concentrations range from trace amounts to saturation.

Answer 2

water

Question 3

If the hydrogen sulfide (H2S)concentration is greater than 2%–3%, carbonyl sulfide (COS), carbon disulfide (CS2), elemental sulfur, organic sulfides, and mercaptans may be present

Answer 3

sulfur species

Question 4

Can damage the brazed aluminum heat exchangers

Answer 4

mercury

Question 5

what means NORM

Answer 5

Naturally occurring radioactive materials

Question 6

A significant amount of corrosion in gas processing is related to oxygen ingress.

Answer 6

oxygen

Question 7

Natural gases commonly are classified according to their _____

Answer 7

liquids content as either lean or rich

Question 8

Apart from natural gases being classified according to their liquids content, they also commonly classified according to the _____

Answer 8

sulfur content as either sweet or sour

Question 9

Gas plant processing includes:

Answer 9

• Dehydration of gas
• Carbon dioxide or nitrogen recovery
• Upgrading subquality gas
• Helium recovery
• Liquefaction

Question 10

_____ to meet a specification, reduce corrosion, and prevent gas hydrate formation.

Answer 10

Dehydration of gas

Question 11

for enhanced oil recovery (EOR)

Answer 11

Carbon dioxide or nitrogen recovery

Question 12

To make the gas marketable, the undesired diluents N2, H2S, and CO2 are removed.

Answer 12

Upgrading subquality gas

Question 13

Natural gas is the primary source of helium.

Answer 13

Helium recovery

Question 14

For easier storage and transportation

Answer 14

Liquefaction

Question 15

Gas and liquids entering the gas plant typically pass through emergency shutdown valves.

Answer 15

Inlet receiving

Question 16

• _____ are critical because downstream gas processing units rely on a continuous gas stream free of liquids, even when surges of liquid enter the plant.
• It is a gas–liquid separator sized to hold the biggest slug a plant will experience.

Answer 16

Slug catchers

Question 17

A _____ refers to a large volume of liquid that suddenly flows through a gas pipeline or processing system.

Answer 17

slug

Question 18

The _____ occurs in a slug catcher.

Answer 18

initial gas–liquid separation

Question 19

Pressure plays a major role in gas processing, as it moves gas from the field, through the gas plant, and into the sales gas line. Plant process streams that undergo compression include the gas leaving inlet receiving.

Answer 19

Inlet Compression

Question 20

To maximize liquids recovery, the inlet gas is typically at _____ when it enters the hydrocarbon recovery section.

Answer 20

700–1,000 psi

Question 21

Compressor types:

Answer 21

• Reciprocating Compressor
• Oil-Free Rotary Screw Compressors

Question 22

Accurately calculating compressor power and capacity is critical in natural gas processing to ensure ______

Answer 22

efficiency, reliability, and cost-effectiveness

Question 23

_____ with liquids present require either polytropic or more rigorous thermodynamic methods to be used.

Answer 23

Screw compressors

Question 24

_____ require knowledge of displacement volumes to compute flow rates. If accurate calculations are needed, equation of state methods should be used, along with information about the compressor performance provided by the vendor.

Answer 24

Reciprocating compressors

Question 25

Gas treating involves removal of the ______ to sufficiently low levels to meet contractual specifications, to minimize pipeline corrosion, or to permit additional processing in the plant without corrosion or plugging problems.

Answer 25

“acid gases” carbon dioxide (CO2) and hydrogen sulfide (H2S) along with other sulfur species

Question 26

_____ is highly toxic, and in the presence of water it forms a weak, corrosive acid.

Answer 26

Hydrogen sulfide

Question 27

_____ is nonflammable and, consequently, large quantities are undesirable in a fuel. Like H2S, it forms a weak, corrosive acid in the presence of water

Answer 27

Carbon dioxide

Question 28

Four scenarios are possible for acid gas removal from natural gas:

Answer 28

1. CO2 removal from a gas that contains no H2S 2. H2S removal from a gas that contains no CO2 3. Simultaneous removal of both CO2 and H2S 4. Selective removal of H2S from a gas that contains both CO2 and H2S

Question 29

Because the concentrations of CO2 and H2S in the raw gas to be processed and the allowable acid gas levels in the final product vary substantially, no single process is markedly superior in all circumstances and, consequently, many processes are presently used.

Answer 29

Purification Process

Question 30

The reactions are reversible. In the regeneration (stripper) column, heat is applied to break the bonds and release the acid gases.

Answer 30

solvent absorption - amines

Question 31

Approximately 93% of the sulfur produced in the United States goes into production of sulfuric acid, which is used extensively in a wide variety of industrial products.

Answer 31

Sulfur recovery

Question 32

The ______ is an industrial method used to recover elemental sulfur (S₈) from hydrogen sulfide (H₂S).

Answer 32

Claus process

Question 33

claus process 1st stage

Answer 33

Combustion: H2S + (3/2)O2 → SO2 + H2O

Question 34

claus process 2nd stage

Answer 34

Catalytic: 2H2S + SO2 → 3S + 2H2O

Question 35

In the claus process, the catalysts used are generally

Answer 35

alumina(Al2O3) or titania (TiO2)

Question 36

Presently, there are no comparable processes for turning CO2 into useful products, although research is underway. The discussion here deals only with using the acid gases in EOR operations or sequestering by injection into a suitable underground reservoir.

Answer 36

Acid Gas Injection