Hydrocarbon processing - Címlapkkft.bme.hu/sites/default/files/8a HP Utilities.pdf · 1 English...
Transcript of Hydrocarbon processing - Címlapkkft.bme.hu/sites/default/files/8a HP Utilities.pdf · 1 English...
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English version based on the presentation of
Szalmásné Dr. Pécsvári Gabriella held in 2014
Hydrocarbon processing Utility units
Feedstock: vacuum residue
Compounds determining the bitumen behaviour:
• Asphaltenes – give the structure of bitumens (heat sensitivity)
• Resin like compounds (elasticity, adhesion)
• Oily parts (aromatic/paraffinic)
Specification of bitumens:
• Softening point
• Penetration
Bitumen production
Goal of bitumen production is to produce different grades bitumens from vacuum
residue. There are two main processes:
1. Mild oxidation with air blowing (temperature: 280-290 °C)
Bitumen production
• Blowing temperature:
– Higher – construction/building bitumen.
– Lower – road bitumen.
• Duration of blowing (residence time):
– Similar effect may be reached at lower temperature.
• Blowing air quantity
• Production of special bitumens:
– Road construction
– Shingle sheet production (Zsindely lemez)
– Insulating plate production
• Modification:
– Blending with special additives (polimers)
– Properties adjustment
2. Modification with special addivives (polimers)
Rubber bitumen
First road fully built from rubber bitumen at Villány
Idea: mixing rubber grist from used vehicle tyres into road bitumen
Innovation: technology was developed jointly at Pannon University and MOL
Advantages: longer lifecycle, lower operating cost
better usage behaviour (higher load capacity, better fatigue properties
/less rapture/)
better adhesion, reduced pot-hole formation
lower traffic noise
lower braking distance
Bitumen production process
117 121
104-A,B,C
103-A,B,C
113
106-C106-A
107
108-A,B
Fúvató levegő
Gudron
Biztonsági gőz
Fúvatott bitumen
Fúvatási gáz
Melegítő olaj
Olajos mosó Vizes mosó
140-150 °C
280-290 °C
Vacuum residue
Safety steam
Blowing air
Oil washer Water washer
Air blowed
bitumen
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Utility units – Hydrogen production
Steam Methane Reforming (SMR) Task: Hydrogen production for
hydrotreaters
Feedstock: methane + water
Product: hydrogen (99,9% purity)
Temperature: 800 – 850 °C
Catalyst: Ni/Al2O3
Steam Methane Reforming
Methane reforming
simple stochiometry
shift reaction is taking place rapidly, paralelly
the whole process is strongly endothermic
CH4 + H2O ↔ CO + 3H2 (steam reforming)
CO + H2O ↔ CO2 + H2 (water shift reaction)
Reforming of heavier hydrocarbons
stochiometry depends on hydrocarbon
cracking may happen as side reaction
endotherm process
CnHm + nH2O ↔ nCO + (n+m/2)H2
CnHm ↔ xC + C(n-x)Hy + (m-y)/2H2
Steam Methane Reforming – Catalyst
Industrial catalysts:
• Prereforming NiO / MgAl2O4
• Steam reforming NiO
• Shift reactions Fe/Cr or Cu/Cr
Ni: Robust, high activity, less sensitive to potential catalyst poisons
most widely used
Catalyst support:
Requirements: good heat resistance, pressure resistance, acidic sites are not
allowed due to cracking
Materials: a-aluminium-oxide, calcium-aluminium-oxide, magnesium-
aluminium-oxide
Steam Methane Reforming – Feed preparation
Task of desulphurisation unit: removal of sulphur and chloride content of feed natural gas, in order
to avoid deactivation and poisoning of reforming catalyst.
Transformation of all sulphur and chloride compounds to hydrogen-sulphde (H2S) and hydrochlorid
acid (HCl)
Catalysts:
Desulphurisation: Co/Mo
H2S and chloride removal: ZnO / CaO
Steam Methane Reforming – Processing Scheme
Prereformer
Fuel gas
Hydrotreater
Export steam
Hydrotreater
Air
Boiler feed water
Hydrogen
Product gas cooler
Steam drum
Steam
reformer
Adiabatic prereforming
Main task of the prereformer is to react all higher hydrocarbons to methane. Advantages:
– No need to fill catalyst to the reformer, oriented to reaction of higher hydrocarbons
– Lower steam/hydrocarbon ratio is possible
– Increased reformer catalyst life time, since the prereformer is provides sulphur defense too
Typical operational temperature is 400-520°C. Desulphurised feed (natural gas/hydrogen) is mixed with high pressure steam upstream of entering the prereformer (45 barg, 450 °C).
Reforming In the reforming part the hydrocarbon feed is converted to synthesis gas, which is mainly comprised of
hydrogen, carbon-monoxide and carbon dioxide, and in small parts unreacted methane
– temperature (800 – 890 °C)
– pressure (25 - 30 barg)
– steam/hydrocarbon ratio (2 - 4.5)
Reforming reactions are always endothermic.
Steam Methane Reforming – Subunits
Shift reactor
• In the shift reactor the carbon-monoxide is transformed to carbon-dioxide
• Operational temperatures of Shift catalysts at start of life cycle is around ~195°C (inlet)
and 313°C (outlet).
Waste heat removal of flue gas
• Flue gas, leaving the radiation section of reformer takes significant amount of heat.
Major part of this heat may be regained with the heat exchanger bundles placed in the
convection zone of the reformer. With this reuse together with the heat absorbed in the
reformer bundles, 90% of the heating value of the fuel gas may be utilised.
Hydrogen purification
• The reaction gas consits hydrogen and carbon-dioxide, together with some carbon-
monoxide, nitrogen and methane. The hydrogen content may be purified up to more
than 99,9% in the PSA unit.
Steam Methane Reforming – Subunits
Hydrogen Purification – PSA
Pressure Swing Adsorption
• High purity >99.9 vol.%
• Simple system
• Fully automated
Impurities may be desorbed via the depressurisation and the adsorber beds can be
regenerated.
The cycles of the adsorbers are delayed compared to each others, in order to provide
continuous product and waste gas flow
Hydrogen Purification – Hydrogen recovery
PSA Cryogenic Membrane
Big unit footstep Small unit footstep Small unit footstep
Medium CAPEX High CAPEX Low CAPEX
Very low OPEX High OPEX Low OPEX
H2 >99 mol % H2 ~ 93 mol % H2 ~ 98 mol %
High H2 loss Low H2 loss Medium H2 loss
No perssure loss Low perssure loss High perssure loss
Goal: Transforming the H2S containing
gases into liquid or solid sulphur
product.
Sulphur removal efficiency 99,5-99,9 %
• Thermal reaction (1000 - 1400 °C)
3H2S + 1,5O2 2H2S + SO2 + H2O
• Catalytic reaction (200 - 340 °C)
2H2S + SO2 3S + 2H2O
Utility units – Claus process
Claus process – Process scheme
The newest catalysts design:
• Fe2O3 and Fe3PO4 on amorph or alpha-aluminium-oxide support
• Na2O/Zn promotors (reducing the SO2 formstion, thus increasing the
sulphur removal efficiency
Claus process – Process chemistry