basic purification
TRANSCRIPT
![Page 1: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/1.jpg)
INTRODUCTION TO PURIFICATION
• FEEDSTREAM OVERVIEW
• PURIFICATION REQUIREMENTS OVERVIEW
• IMPURITIES AND THEIR EFFECTS
• IMPURITIES REMOVAL MECHANISM
![Page 2: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/2.jpg)
FEEDSTREAM OVERVIEW
• ETHYLENE is the main raw material for producing polyethylene– ETHYLENE = C2H4
– B.P.= -185.3 OC
![Page 3: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/3.jpg)
FEEDSTREAM OVERVIEW
• COMONOMER• HEXENE OR BUTENE - is used as a
comonomer for branching the polymer chain which directly affect the resin density– HEXENE = C6H12
– B.P. = 63.5 oC
– BUTENE = C4H8
– B.P. = -6.3 OC
![Page 4: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/4.jpg)
FEEDSTREAM OVERVIEW
• HYDROGEN - is generally used as a chain terminating agent in the polymerization reaction to control the length of the polymer molecules or the Melt Index of the M catalyzed resin– HYDROGEN = H2
– B.P. = -252.7 O C
![Page 5: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/5.jpg)
FEEDSTREAM OVERVIEW
• HEXANE - is used as an Induced Condensing Agent.– HEXANE = C6H14
– B.P. = 67.0 O C
![Page 6: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/6.jpg)
FEEDSTREAM OVERVIEW
• NITROGEN - is used to carry into the reactor and as purge gas to purge the product for un-reacted hydrocarbon. It is also used to purge equipment during operation and for preparation of equipment for maintenance.– NITROGEN = N2
![Page 7: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/7.jpg)
FEEDSTREAM OVERVIEW
• TEAL OR T2 - used as co-catalyst in the reaction process when using UCAT A or “M” catalyst.– TEAL = (C2H5)3Al
– B.P. = 186 OC
![Page 8: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/8.jpg)
FEEDSTREAM OVERVIEW
• PROPYLENE - main raw material in the production of the polypropylene.– PROPYLENE - C3H6
– B.P. = -169.2 OC
![Page 9: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/9.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• All reactor feed streams must be treated to remove impurities, which have an adverse effect on the catalyst. The purification facilities for each feed stream may consist of one or more operations each of which are specific to the impurities which are being removed.
![Page 10: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/10.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• Here at JGSPC, an Ethylene Purification unit is consist of facilities for the removal of Sulfur (S2), Carbon Monoxide(CO), Oxygen(O2) and Water(H2O).
![Page 11: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/11.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• The comonomer Purification System is consist of a Degassing Column to remove Carbon Monoxide (CO); Carbon Dioxide(CO2), Oxygen(O2) and molecular sieve Dryer to remove trace amount of Water or Moisture(H2O).
![Page 12: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/12.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• The Hydrogen feed stream goes to a molecular sieve dryer to remove trace amounts of water(H2O).
![Page 13: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/13.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• Nitrogen Purification unit consists of a Deoxo Vessel to remove trace amounts of Oxygen(O2) and then through a molecular sieve Dryer to remove water(H2O).
![Page 14: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/14.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• Hexane Purification system is consist of a Degassing Column to remove Carbon Monoxide (CO), Carbon Dioxide(CO2), Oxygen(O2) and molecular sieve Dryer to remove trace amount of Water or Moisture(H2O).
![Page 15: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/15.jpg)
PURIFICATION REQUIREMENTS OVERVIEW
• Propylene Purification unit is consist of a Degassing Column to remove Carbon Monoxide (CO), Carbon Dioxide(CO2), Oxygen(O2); and other equipment for the removal of Sulfur(S2), Methylacetylene/ Acetylene/Propadiene (MAP) and molecular sieve Dryer to remove trace amount of Water (H2O).
![Page 16: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/16.jpg)
EFFECTS OF CONTAMINANTS
• DEACTIVATE REACTION CATALYST– React with active catalyst sites– Block polymerization sites– Cause incorrect catalyst mixing proportion
• ALTER RESIN PROPERTIES– Hinder comonomer incorporation– Change polymer chain length and branching
![Page 17: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/17.jpg)
EFFECTS OF CONTAMINANTS
• ALTER REACTION OPERATING CONDITIONS– Take blow-off to remove impurities– Reduce temperature to maintain product
properties– Reduce rates
• RAISE REACTANTS QUANTITIES REQUIRED
![Page 18: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/18.jpg)
EFFECTS OF CONTAMINANTS
– More components require more feed to the reactor
• INCREASE RESIDUALS IN RESIN– Ash content will increase
• CAUSE REACTOR CONTINUITY PROBLEMS– Will cause sheeting or chunking
![Page 19: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/19.jpg)
EFFECTS OF CONTAMINANTS
• CHANGE SELECTIVITY AND ACTIVITY OF PURIFICATION CATALYST– Normal components or impurity for which the
purification stage was designed may not be removed due to presence of other impurities.
– Unwanted side reactions may cause catalyst to become inactive
![Page 20: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/20.jpg)
EFFECTS OF CONTAMINANTS
• CAUSE DECOMPOSITION OF RAW MATERIALS– Impurities may react with materials to form
waste product and further contamination– Render materials useless
• CAUSE LOSSES OF RAW MATERIALS– May need to run excessive column vents or
tails to remove unwanted contaminants
![Page 21: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/21.jpg)
EFFECTS OF CONTAMINANTS
• CAUSE SAFETY PROBLEMS– Impurities may react with purification catalyst
or raw materials and form hazardous by-products (acetylides, polymers, oil)
![Page 22: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/22.jpg)
IMPURITY EFFECTS ON UCAT- A CATALYST REACTION
• CO is an effective kill gas for the catalyzed reaction
• CO2 significantly reduces U-A catalyst productivity
• O2, H2O, Acetylene (below 20 ppm) do not poison U-A catalyst
• MWD of U-A polymerized resin is not modified by impurities
• Slight, but unimportant decrease of MI was observed with water and oxygen
![Page 23: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/23.jpg)
IMPURITY EFFECTS ON UCAT- A CATALYST REACTION
• In general, U-A catalyst is less affected by feed stream impurities due to presence of TEAL in the reactor
• Some impurities in very small quantities are pro-static agents and may effect the stability of the process by inducing more static charge to resin particle, than are being discharge
![Page 24: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/24.jpg)
IMPURITIES REMOVAL MECHANISM
• CHEMICAL ADSORPTION– Impurity is adsorbed into a porous material bed
(catalyst) and becomes a third component that stays in the porous material is covered with this third compound, regeneration of the bed is necessary. Example: Deoxo Beds
– Regeneration - the process of bringing up spent catalyst to its active state. (Using heated Nitrogen).
![Page 25: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/25.jpg)
IMPURITIES REMOVAL MECHANISM
• HYDROGENERATION– Another phase of chemical adsorption, this process
consist of the adsorption of the impurity in the porous bed, reaction with another component (H2) and de-sorption of the product caused by this reaction. Example: MAP Removal Bed where acetylene is adsorbed in the palladium catalyst and while it is adsorbed, it reacts with the hydrogen injected at the inlet of the bed. The product of this reaction,ethylene or ethane goes in the stream
![Page 26: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/26.jpg)
IMPURITIES REMOVAL MECHANISM
• PHYSICAL ADSORPTION– Removes impurities based on size or polarity.
Example: Molecular sieves where water stays adsorbed into the sieve and is de-sorbed during the sieve regeneration. The sieve material does not react nor catalyze any reaction so regeneration is a physical process
![Page 27: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/27.jpg)
FACTORS AFFECTING ADSORPTION
• AREA EXPOSED– Porosity
• VELOCITY– Residence time
• CONCENTRATION– Higher - Harder
• LENGTH OF REACTION ZONE(LRZ)– Longer - Better
![Page 28: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/28.jpg)
PROCESS
• FOR GAS STREAM (ETHYLENE)– Heat up– Sulfur removal - G72D Zinc Oxide adsorbent– CO removal - G66B type 2130 zinc oxide
hydrogenation catalyst
– O2 removal - UCC1101 copper chromite on silicon deoxide
– Dryer - UOP 13 XPG molecular sieve, sodium alumino silicate
![Page 29: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/29.jpg)
PROCESS
• FOR LIQUID STREAM (PROPYLENE)– Degassing - distillation– Cooling - prevent temperature runaway– Sulfur removal - ALCOA Selexorb COS– MAP removal - G68F– Dryer - UOP 13 XPG– Filter - particulate removal
![Page 30: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/30.jpg)
POINTS OF CONCERN• BED TEMPERATURE ALARMS
• BED TEMPERATURE ALARMS AND MONITORING
• VESSEL PURGING AND CATALYST DEACTIVATION
• VENTS
• INSULATION OF PROCESS EQUIPMENTS AND LINES
• REGENERATION NITROGEN PIPING
![Page 31: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/31.jpg)
CHEMICAL REACTION
• SULFUR REMOVAL– H2S + ZnO ZnS + H20
– COS + ZnO ZnS + CO2
• CO REMOVAL– CO + CuO CO2 + Cu
– CO + Cu2O CO2 + Cu
![Page 32: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/32.jpg)
CHEMICAL REACTION
• O2 REMOVAL
– 2 Cu + 0.5 O2 Cu2O
– 2 Cu + O2 CuO
• C2 OXIDATION
– 6 Cu2O + C2H4 2 CO2 + H2O + 12 Cu
• COPPER ACETYLIDE REMOVAL– CuC=CCU + H2 Cu + Hydrocarbon
![Page 33: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/33.jpg)
PROPYLENE
• FEED SUPPLY
• PRESSURE 340 psig/2344kpag min. 350psig/2413kpag normal 370 psig/2551kpag max.
• TEMPERATURE -10 oC min. 30 oC normal 40 oC max.
![Page 34: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/34.jpg)
PROPYLENE
• DESIGN FLOWRATES– 45,300 lb/hr / 20,548 kg/hr Normal– 51,000 lb/hr / 23,170 kg/hr Maximum
• NORMAL OPERATING PRESSURE– 305 psig / 2,100 kpag – Column pressure controlled with a flow
controller on the steam to the reboiler
![Page 35: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/35.jpg)
PROPYLENE• FEEDSTREAM QUALITY
– IMPURITY MAX.ppmV FINAL PRODUCT
– CO2 5 <0.1
– CO 5 NIL
– O2 5 NIL
– H2O 5 <0.1
– S2 3ppmW 0.1
– Oxygenated HC including ALCOHOL 10 0.1
– MAP 10 <0.5
![Page 36: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/36.jpg)
PROPYLENE
• DESIGN BASIS– Distillation (Stripping) step for removal of CO2,
CO, and O2
• DESIGN OPERATION AND SAFETY CONSIDERATION– Turndown from 100% of the flow required for the
product with the maximum demand to 50 % of the flow required for the product with the minimum demand
![Page 37: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/37.jpg)
PROPYLENE
• ADSORBENT(SULFUR REMOVAL)– ALCOA SELEXSORB COS (Promoted
Activated Alumina)
• SAFETY CONSIDERATIONS– Regeneration with hot nitrogen– No preload– 3-5 year bed life to replacement– 18 hour regeneration time
![Page 38: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/38.jpg)
PROPYLENE
• ADSORBENT(MAP REMOVAL)– UNITED CATALYST G-68F (Palladium)
• SELECTIVITY– METHYLACETYLENE, ETHYLENE,
PROPADIENE, PROPYLENE (EXCESS O2 WILL REACT WITH UNSATURATED HYDROCARBONS)
![Page 39: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/39.jpg)
PROPYLENE
• SAFETY CONSIDERATIONS– Non-regenerable
– Sulfur and Arsine irreversible poisons to G-68F Normal Sulfur and Arsine concentrations must be kept less than 0.1 ppmw
– High temperature shutdown normally set at 50 oC
– 3-5 year bed replacement
– H2 feed to bed stops automatically on low propylene flow
![Page 40: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/40.jpg)
PROPYLENE
• ADSORBENT(DRYER)– UNION CARBIDE 13 XPG Molecular sieves
• SAFETY CONSIDERATIONS– Regeneration with hot Nitrogen– Controlled preload with Propylene to prevent
temperature excursions– 3-5 year bed life to replacement– 7.5 hour regeneration time
![Page 41: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/41.jpg)
ETHYLENE
• PRESSURE– Low 2827 kpag– High 3477 kpag– High-High 3571 kpag
• DESIGN FLOW RATES– Minimum 6,000 lb/hr ( 2,722 kg/hr)– Normal 11,572 lb/hr (25,458 kg/hr)– Maximum 14,464 lb/hr (31,820 kg/hr)
![Page 42: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/42.jpg)
ETHYLENE
• TEMPERATURE– Minimum -24 oC– Normal 30 oC– Maximum 150 oC
![Page 43: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/43.jpg)
ETHYLENE
• EMERGENCY SHUTDOWN SYSTEM (ESD)– In the event of major emergencies such as fire
or gas release– Temperature in the purification beds is high
(125oC), two thermocouples sustained for 2 minutes
![Page 44: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/44.jpg)
ETHYLENE
• FEEDSTREAM PURIFICATION• IMPURITY MAX. FINAL PROD.
– CO 0.2 <0.1
– O2 0.5 <0.1
– H2O 5.0 <0.1
– CH3OH 5.0 <0.1
– S2 AS H2S 0.2 <0.1
– CARBONYLS 0.1 <0.1 AS MEK
![Page 45: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/45.jpg)
ETHYLENE
• SEQUENCE OF REMOVAL– SULFUR (G72D, ZnO)– CARBON MONOXIDE (G66B, CuO)– OXYGEN (UCC 1101, CuCr)– WATER, METHANOL, CARBONYLS (UOP
13XPG)
![Page 46: Basic Purification](https://reader031.vdocuments.site/reader031/viewer/2022012304/5524f24a550346ad6e8b45f3/html5/thumbnails/46.jpg)
ETHYLENE
• EXTENDED SHUTDOWN– 12 hours to 7 days, to be depressurized to 1000
kpag– > 7 days, system to be depressurized and kept
under Nitrogen blanket