Technology in PP production

Introduction

In last two decades, with combination of technology andadvantageous cost position polypropylene production is increased to massivelevel. Production forecast of polypropylene for next few years is positive anddue to competitive cost consumption is also expected to increase in nextdecade. Today we are at the edge where raw material of PP is fixed and becominga matter of massive cost. All the producers are planning and developing newtechnologies where they can increase product yield or they can produce innovative product which could be either customer friendly or it could be smart polymeror eco-friendly plastic. R&D cell of different companies are not onlyinnovating on catalyst but also improving structure property relation inpolymer designing. Technology provider companies are also coming with new plantdesign and with devices which are helpful in efficiency increment. As China isgrowing as major producing countries technology provider are building up hugeplant with better product knowledge, to construct such huge production facility study is continuously going on to understand nature of polymer, relationbetween different molecular structure, morphology and fracture paraphernaliaof polymer. In near future we will see better and deeper study on molecular,morphological and crystallization mechanisms. In this article we have mentionedsome new upcoming technology for polypropylene production we hope that thistechnology may remain unbeaten in forthcoming years.

When it comes to technologicalupdate main important goes to yield percentage, mainly asked question is whatis yield percentage? For light olefins, especially for propylene and butylenesthis remains a major challenge. Propylene is important product to manufacturePP, ACN, Propylene oxide, Oxo-alcohols, and Cumene, almost 90% of total propylene production is used to manufacturer these above products. It is expected that till year2010 demand for propylene and its derivatives will increase at 4.8% annually,which is approximately 67 million tons per year by 2005. Now a days ethyleneemerge as important competitive of propylene and useful in various technologyyet lot more work to be done in proper technological development of ethyleneand polyethylene. The easier and cheaper technology of propylene to polypropylene will remain dark horse, as margins are also good and revenues generation is alsoeasier for high value polypropylene.

Types of Technology: Process descriptions

FCC: FCC is the only conventional and proven technology, in new the FCC process new features elevated like OptimixTM feed distributors,the Vortex Separation SystemSM (VSSSM) riser termination device and a combustorstyle regenerator. The new Catalyst coolers, (RxCatSM) design and selectiverecycle can be added to manufacturing line which can increase flexibility forfeed and product demands by improving morphological structure.

RFCC: Other similar process is the RFCC process which uses similarreactor technology and is targeted for residual feeds greater than 4 wt-%Conradson carbon. In this technology there is a two stage regenerator withcatalyst cooling which is typically used to control the higher coke production and resulting heat.

Petro-FCC: This process is similar to a conventional FCC as far as concernin mechanical terms, yields of this process is increased up to 20% to 25%. Inthe Petro-FCC process, to enhance light olefin production and to help aromatics production, there is incorporation of additional reaction severity along withthe RxCat design; Optimix feed distribution and VSS riser termination technology.

MSCC: Developed by BARCO and licensedexclusively by UOP, the MSCC process reactor technology uses an ultra-shortcontact time in a proprietary design contact zone (without the use of aconventional reactor riser). It can be applied to all feeds, but its advantagesgrow when resid feeds are being processed.

Catalytic Cracking

In process of Catalytic cracking we breaks down/covert the larger, heavier, and more complexhydrocarbon molecules into simpler and lighter molecules. This could bepossible by the action of heating with aided by the presence of a catalyst butin absence of extra hydrogen.

During this process we are using heavy oils (fuel oil components) as feeding material which could beconverted into lighter and more valuable products (As early describe we can useLPG, gasoline and middle distillate components).

The catalytic cracking unit is known as the Fluidized Catalytic Cracking or FCC as most of the product come out in fluid form. Traditionally we know them as gasoline, LPG, etcGenerally FCC is use to crack down and distillate energy product as per demand pattern. Last but not list, a third mode is getting importance, which provide us a maximum olefin mode which maximizes LPG, propylene and butylene. In S Asia, a major olefin produce use FCC to produce olefins, here this producer also get benefited with value added LPG and other petroleum products.

This process is in absence of Hydrogen hence FCC is also known vacuum gas oil (VGO) distillation column. This column has again three types inherent.

- VGO

- Hydro-treated VGO

- VGO mixed with VR (Process is known as Resid FCC or RFCC).

Generally the VGO material or the FCC feed is coming from the Vacuum Distillation Column in the CDU/VDU process or from the Coker.

PP by FCC process:

Propylene is one of the fastest growing petrochemicals intermediate, with driven primarily by the high growth rate of polypropylene. Polypropylene demand currently is growing in the U.S. at 6 %/year, and in some regions of the world the growth rate is considerably higher. Polypropylene is useful in production of PP fibre, filament and in new generation of hygiene Nonwoven. With the help of steam cracking we are currently supplying most of the worlds propylene but as per increasing demand and growth of ethylene and allied technology it is important to keep up new innovative production technology in practice. Now a day there is steam cracking capacity is based on ethane feed, which produces little propylene.

As demand increases refiners are successfully implementing catalyst which can boost the operating conditions. E.g. traditional Ziegler-Natta ZSM-5 additive remain more help with new innovative additives. This not only improves the production capacity but also improve the operation conditions. Propylene production from FCC units is the second most important source of worldwide petrochemical propylene supply. Compare to S Asian in U.S.A, FCC propylene production is lower compare to steam cracker propylene.

It is important to develop new technology with catalytic cracking of olefinic naphtha which give more production compare to current production technology, also this help in de-bottlenecking of cost of production as the feedstock material is now gas and not fluid.

Other Process

PCC (Propylene Catalytic Cracker) ExxonMobil

ExxonMobil was working with the below criteria for a commercially viable on-purpose propylene process based on naphtha cracking.

• Economical investment, operating cost
• Reliable and demonstrated reaction system and catalyst
• Selectivity to high value co-products
• Production of residual naphtha having desired properties for gasoline blending

The above criteria give birth to an evolutionary technology that confirmed the need for a new process to achieve the desired characteristics which listed above, together with its affiliate, ExxonMobil Research and Engineering Co., an improved process concept was identifier and subsequently was progressed through the development phase.

ExxonMobil now is pleased to announce the development of a new fluid solid naphtha cracking process called the ExxonMobil PCCSM Process (where PCC stands for Propylene Catalytic Cracking). The PCC Process employs an optimum catalyst, reactor design, and patented combination of optimum operating conditions to achieve a high degree of reaction selectivity. These provide PCC with economic advantages over prior fluid solids configurations.

The key distinction between PCC and prior fluid solids technologies is the use of a patented combination of selective reaction conditions, proprietary equipment, and catalyst designed to crack feed into propylene and other light olefins. These patented conditions and process configuration are designed to minimize the downgrade of gasoline molecules to low value fuel components.

Emerging FCC Based Propylene Technologies

Catalyst and Modifiers

• In last few years Borealis come with the two new metallocene catalysts first is Uni-Modal and other is Bi-Modal. Uni-Modal metallocenes has a single reactive site on polymer and useful in making linear polymer chains with narrow distributions of molecular weight and co-monomers. There were some papers presented on the usefulness of Uni-Modal catalyst in Borstar PE technology. Bi-Modal metallocenes catalyst useful as starter of polymer chain for making heavy molecular chain/weight and in making co-monomers.

• Another development in the catalyst is carried out by the Rohm and Haas. This company had described an innovative technology solution useful in Formulating for Optimum Rheology in waterborne coatings. This technology was developed to respond the challenges faced in popular deeply tinted paints.

The same rheology modifiers were useful to Rohm and Haas to develop an innovative new technology for non-ionic thickeners. These modifiers were useful in developing new technology which could be applicable across the broad colorant technology and with various binders. Overall it was useful and successful to enhance aesthetic properties of PP.

Development in Extrusion Machinery

Development is also going on in extrusion line, the new extruder line was provided by the Krauss-Maffei Berstorffs. This line delivers maximum output of 760kg/hour to 1100kg/hour. The longer processing units increased the specific melt input to total output. This new system was provided to its long standing customer.

The same technology may be useful in producing PVC pipe also. Riccini is now planning to come up with PP well pipe as alternative solution. This would be chipper compare to conventional material PVC. In Middle layer of pipe there will be CaCO₃ filler. The inner and outer layer of pipe will be made up with PP only.

Long Spin Process:

This would be like a general extrusion process only but with long quenching path. Initially Polypropylene melt was extruded through a die-plate perforated by many small holes to make individual fibers. The middle of portion of the technology remains same where the finishing and winding part is imparted. In last process of Packing there will be change according to application. Process would be depends on end use. You can cut it and made staple fibre, you can make filament yarn or you can process the yarn with texturized BCF (Bulk continuous fiber) for yarn useful in carpet manufacturing.

Short Spin Process:

The "short spin" process uses a faster and short quenching path for the extruded melt and is often used for manufacturing of staple fiber. The tow is then passed through the usual stretched cutting line. This staple fiber goes through either conventional spinning, weaving process or with the help of latest technology it formed into a non-woven fabric or mat.

This fibers are easily use in the melt blown process, where the high velocity air blows through a very fluid Polypropylene melt and sprays a discontinuous stream of numerous, very fine fibers onto a moving belt. The fibers are bonded together to get wound onto a roll already in the form of a fabric, such form are useful for Nonwoven fabric manufacturing.

The spun-bond process yields a non-woven material formed directly from fine, yet continuous fibers spun at high speed. This process is highly useful in various combinations with the melt blown technology to make multilayer non-woven fabrics with enhanced properties and useful applications which suit to modern life style.

Hollow PP fibres with a high-stiffness:

New hollow olefins fibers were developed by Engineers at Intek Plastics Inc. This new technology facilitates to extrude hollow thermoplastic beams reinforced with a high-stiffness core made of a thermoplastic material strengthened with 1/2-inch-long glass fibers. Intek claims its technology, known as very high modulus extrusion (VHME), offers physical properties superior to those of polypropylene, and more-expensive composite engineered thermoplastics fibers, e.g. polycarbonates.

The PP fibre extruded through this technology has good strength and impact resistance, sheathed by inner and outer layers of Polypropylene. It is fact that due to high strength in fiber, It is difficult to maintain cut length of fiber during processing to obtain the unique properties of high strength and outstanding impact resistance. Here process face hurdles only in speed. If Quantity matters every company can resolve it successfully.

Conclusion:

It is understood that in current situation to have a fuel refinery is not a profitable venture and FCC is now no more a fuel producing mechanism. As per the current market propylene yield in FCC is only 4% to 5% of the feed material. It is profitable for all the PP production facility owner to go for a new FCC technology where average propylene yield is approx high as 20% of the feed materials. As per the paper available, the HSFCC process is in best position to produce light olefins for petrochemicals usage along with fuel products. Based on the intrinsic features of HSFCC, maximum propylene yield and aromatics can be obtained by the combination of an optimized catalyst system and operating conditions.

According to major technology consulting firm, global FCC capacity with the help of allied technology, is expected to grow by approximately 19% between 2006 and 2015. Across that same time, polymer grade propylene production from FCC units is projected to grow by nearly 32%.

References:

• Reliance Industries Limited, Maker Chambers IV, Nariman Point, Mumbai.
• ExxonMobil Process Research Laboratories
• ExxonMobil Research and Engineering Company
• Polypropylene Development - From Catalyst to Customer, SPE International Polyolefins 2007 Conference, Houston/TX, USA, February 25-28
• Purvin & Gertz
• New Catalytic Cracking Process to Maximize Refinery Propylene By: Ali G. Maadhah, Yuuichirou Fujiyama, Halim Redhwi and Mohammed Abul-Hamayel, Abdullah Aitani* and Mian Saeed, and Christopher Dean.

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