c2 acetylene hydrogenation
DESCRIPTION
Acetylene Hydrogenation - Consultancy Ethylene Plant Flowsheets Placement of Acetylene Hydrogenation Reactor Cracker Feedstock / Product Variability Acetylene Reactor Feeds Reasons for Acetylene Removal Reacting Components and Conditions Reactor Operation and Reacting Components Reactor Design Selectivity vs. Temperature and Ethane Formation Effect of CO Poisons Green Oil Turndown H/D Ratio and Pressure Drop Thermocouple Placement Start-up Problems During Start-up Shut Down Regeneration Catalyst Experience, Problems and Other Information Front End / Tail End ComparisonTRANSCRIPT
C2PT Catalyst Process Technology
C2 Acetylene Hydrogenation
Ethane usually recovered from natural gas fields mainly USA
Propane/butane recovered from gas fields middle east, Texas etc. Kuwait has a large butane recovery system. Also can come from LNG plants
Refinery naphtha / condensate C5 to C7 paraffin based low octane naphtha from refineries also from natural gas / oil well head production
Light and heavy gas oils refinery based (200 to 350°C) AGO and (350 to 550 °C) VGO
The more paraffinic the feedstock the higher the ethylene yields and the greater the value of the co-products
Feedstock Sources
Sulfur Cracks in furnaces to give H2S and COS. Mercaptans in C3/C4 cuts, RSH and thiophenes in gasoline, benzo-thiophenes in fuel oil
Arsenic Organic or arsine Makes arsine in the furnaces and some remains as organic Mercury Metallic / organic Decomposes to metallic some remains as organic Ballast water Sea water from shipping feed stock Metals
Nickel, sodium, vanadium, iron from heavy feedstocks FCCU off gas (gas compressor suction, developing trend) NOx, H2S, amines, SbH3, As , COS, O2, CO2 plus others
Major Feedstock Impurities
Base Intermediate Final
C2H2 + H2 = C2H4 + H2 = C2H6
C2H2 = CH2 CH CH CH2 Butadiene
= Green oil
CH3 C CH + H2 Methyl Acetylene
= CH3 CH CH2 propylene
CH2 C CH2 + H2 Propadiene
= CH3 CH CH2 propylene
CH2 CH CH CH2 + H2 Butadiene
= CH3 CH CH2 Butylene
CH2 CH CH CH2 Butadiene
= Green oil
Relative reactivities
C2H2 > C4H6 > C3H4 (MA) >> C3H4 (PD) > C2H4
Acetylene Basic Chemistry
Conventional Ethylene Flowsheet
Cracking Furnaces Quench Compression
Stages 1-3 Caustic Scrubber
Compression Stage 4 Dry
Figure 1. Simplified Ethylene Flowsheet Cracking/Preliminary Clean-Up
Fuel Oil Gasoline
CO2 H2S H2O
H2 CO C1 C2 C3 C4 C5+
*
* - Possible C2H2 hydrogenation step, normally called wet gas stream
Front End Systems
H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10
C5+
Figure 2. Front End De-Ethanizer
C3H4 C3H6 C3H8 C4H6 C4H8 C4H10
C5+
DE-
ETH
AN
ISER
DE-
MET
HA
NIS
ER
C2 S
PLIT
TER
H2 CO CH4
C2H4
C2H6
Acetylene Hydrogenation
Reactor
Recycled to Cracking Furnaces
( Pd on alumina)
H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10
C5+
C4H6 C4H8 C4H10
C5+
DE-
PRO
PAN
ISER
DE-
MET
HA
NIS
ER
DE-
ETH
AN
ISER
H2 CO CH4
C3H4 C3H6 C3H8
C2 S
PLIT
TER
Figure 3. Front End De-Propanizer
Acetylene Hydrogenation
Reactor
C2H4
C2H6 Recycled to
Cracking Furnaces
( Pd on alumina)
DE-
MET
HA
NIS
ER
DE-
ETH
AN
ISER
C2 S
PLIT
TER
H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10
C5+
H2 CO CH4
C3H4 C3H6 C3H8 C4H6 C4H8 C4H10
C5+
Acetylene Hydrogenation
Reactor
H2 CO
Figure 4. Tail End De-Ethanizer
C2H6 Recycled to
Cracking Furnaces
C2H4
( Pd on alumina)
Ethylene Plant Flowsheets
Placement of Acetylene Hydrogenation Reactor Cracker Feedstock / Product Variability
Acetylene Reactor Feeds Reasons for Acetylene Removal
Reacting Components and Conditions Reactor Operation and Reacting Components
Reactor Design Selectivity vs. Temperature and Ethane Formation
Effect of CO Poisons
Green Oil Turndown
H/D Ratio and Pressure Drop Thermocouple Placement
Start-up Problems During Start-up
Shut Down Regeneration
Catalyst Experience, Problems and Other Information Front End / Tail End Comparison
Acetylene Hydrogenation
