Petrochemical industry is being chosen as our main topic for the introduction to Chemical Engineering assignment. Petrochemical is the second level products being derived from crude oil after several refining processes. These chemicals are typically extracted during the refining process as crude oil and gas are distilled or cracked, and they can be utilized in a wide variety of ways.
Petrochemical can be used to manufacture polyvinyl chloride (PVC). PVC is one of the oldest synthetic materials with the longest history in industrial production. Its early history is of multiple and accidental discovery in different places at different times as well as unsuccessful quests for commercial application. During the 1950’s many more companies started to produce PVC and volumes increased dramatically around the world. PVC products rapidly became essential to the construction industry; the plastic’s resistance to light, chemicals and corrosion made it the best option for building applications. Improvement made to the materials’ resistance to extreme temperatures, allowed for PVC to be transporting water to thousands of homes and industries. PVC’s low cost, excellent durability and process ability make it the material of choice for dozens of industries such as health care, IT, transport, textiles and construction.
The chemical process for making PVC involves taking the simplest unit, called the monomer, and linking these monomer molecules together in the polymerization process. Various additives including stabilizers and plasticizers need to be added to PVC resin to create a ‘compound’ that meets the requirement of the end product and of the processing technology to be used.
Importance of Petrochemical Industry in Our Society
The petrochemical industry is a complex industry that affects all spheres of life. Most items used in everyday life such as plastic products and soaps owe their existence to petrochemicals. The petrochemical industry connects downstream sectors such as pharmaceuticals with the upstream oil and gas industry. The petrochemical industry converts feed stocks such as naphtha and natural gas components such as butane, ethane and propane through steam cracking or catalytic cracking into petrochemical building blocks such as olefins and aromatics. While olefins include ethylene, propylene, methanol and C4 stream such as butadiene, aromatics include benzene, toluene and xylene. The petrochemicals of commercial importance in the petrochemical industry include ethylene, propylene, benzene and xylene. These petrochemical building blocks are further processed to yield final products such as paints, polyester and plastics. Take ethylene for instance. It is processed into ethyl benzene, ethylene oxide, ethylene dichloride, ethyl alcohol, acetaldehyde and polyethylene. These undergo further transformation to yield a wide range of products such as tyres, detergents, agrochemicals and plastic products.
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Originally, most plastics were made from the resins of plant matter. But it wasn’t long before plastics were developed from petrochemicals. The packaging industry, the leading user of plastics, accounts for about one-third of total U.S. production. The building industry ranks second, which uses plastic to make insulation, moulding, pipes, roofing, siding, and frames for doors and windows. Other industries, including automobile and truck manufacturing, also rely heavily on plastics. The United States was hardly alone in its rising use of petroleum products. Throughout the world, increased industrialization and rapid population growth created new and greater demands for oil. By the late 1950s, petrochemicals became one of the largest industries, and control over the sources and transportation of oil became a major national and international political issue.
The Supply and Demand
The raw material used for the production Poly Vinyl Chloride (PVC) is Vinyl Chloride Monomer (VCM). Naphtha, which refers to a several different liquid mixtures of hydrocarbon, is the major feed stock used for the production of VCM. The global VCM supply capacity in the year 2009 was 40.0 million tons which 50.8 % of it is based on Naphtha as feedstock. 27.2 % of the global capacity was based on Natural gas for feedstock followed by 17.2% by coal while only 4.7 % of the global capacity was based on other feed stocks. In terms of region oriented, Asia- Pacific had the largest production capacity in 2009 with 18.1 million tons of production which stands 45.1% of the market share followed by Europe with a production capacity of 10.4 million tons and a share of 25.8%. The Middle East had the capacity of 2.0 million tons and a share of 5.2% while South and Central America were closely behind with 1.6 million tons of production capacity with a share of 3.9%.
Based on the report “Vinyl Chloride Monomer (VCM) Global Dynamics to 2020”, global VCM demand in the year 2000 was 20.7 million tons and it grew at a compound annual growth rate (CAGR) of 3.8% from the year 2000 to 2009 in which the demand in the latter year had reached 29 million tons. The report has also indicates that there will be increase in demand of VCM with growth of are a CAGR of 5.4% from 2009 to 2020. This means if the report’s expectation is correct, the demand of VCM this year will be 32 million tones and by the year 2020, the demand will be reaching 50 million tones. Out of the 29 million tons of VCM demand in the year 2009, Asia-Pacific has the highest demand in the industry with 16.4 million tons with a major share of 56.4%. The North America had a demand of 5.9 million tons and its share was 20.3% while Europe had a VCM demand of 4.8 million tons, followed by South and Central America with demand of 1.2 million tons. The demand share owned by Europe was 16.5% while 4.1% of demand market share is occupied by South and Central America. The Middle East had a demand of only mere 0.8 million tons along with demand share of only 2.7%.
In conclusion, we can see that the major demand of VCM is in Asia Pacific and this is also where the production capacity of VCM is highest in a region around the world. Hence, we can conclude that the production capacity is usually closely related to the demand of the region.
Prospect of the industry
The production of PVC is a chemical industry. To be more specific, it is a synthetic material industry. It is considered a segment of overall chemical industry with manufacturers representing 20% of chemical industry. The plastic industry, which manufacturing of PVC is, stands around 70% of the whole synthetic material industry which also includes rubber and manmade fibres.
The production of PVC requires a lot of process which in turn will require a big plant for the manufacturing as well as storing. The manufacturing process is complex which requires an expertise in the field. Hence, the industry requires the skill and knowledge of a chemical engineer to maintain the plant as well as solving problem that exists within the manufacturing process. Besides, transportation of raw materials is also needed to be coordinated by the manufacturer to lower to cost to yield more profit.
From the supply and demand perspectives, both of it is growing from year to year basis which is thoroughly discussed at “Supply and Demand” section. The reason to the increase in demand is due to the usage of this PVC material, mainly in piping but also diversify to other utilities like plastic for manufacturing of table lamp. On the other hand , the supply of raw material increases due to the demand.
The industry plays an important role to the consumer in providing them the product as well as to the economy in making profit and providing jobs opportunity.
Impact on the Environment
During the manufacturing of PVC process, wastes such as production residue sand installation waste which give impact on the environment will be released out. vinyl chloride monomer is used to produce the polymer polyvinyl chloride (PVC).
VCM can be a carcinogen, can cause a rare form of cancer which known as angiosarcoma. Excluding its flammability potential at release, VCM quickly dissipates posing slight threat to human health in form of diluted form and quickly degenerates when exposed to normal daylight as in the open atmosphere. During the polymerization process, basically all of the VCM is changed into the inert polymer chains that form the PVC plastic. The possibility of residual unpolymerised VCM to stay on in the polymer and eventually transfer into food from PVC packaging is high.
Some of the liquid petroleum hydrocarbon will be released into the environment like the ocean or coastal waters due to human activity, and is a form of pollution. In case the balance of ecosystem will be affected.
In the process, the combustion of fossil fuels produces greenhouse gases and other air pollutants as by-products. In Addition, oil spill is a release of a petroleum hydrocarbon into the environment due to manufacturing PVC process.
In other to reduce the impact on the environment, an capable waste management system will reduce the not being re-used and make the most of the use of economically and environmentally rational recovery schemes.
Step of Incineration with Energy Recovery can be taken. Oil that used in PVC production can be utilised as a minimum twice, Incorporating PVC consumer products can be under controlled and reduces the amount of PVC going to landfill and reduces the pollutions. The modern incinerators are equipped with pollution control equipment and run to the highest standards therefore it can help to minimise the release of emissions to the environment. In addition, mechanical and feedstock recycling can implemented
Moreover, anything of the PVC recovery process, residual fraction of waste is contained which not recyclable. Controlled landfill still remains a disposal option in the limited fraction. The consumer product which containing PVC presence in landfill does not constitute a major risk to the environment is confirmed by finding of independent studies.
how PVC is manufactured
(Electrolysis, Chlorination & VCM Cracker)
1 Electrolysis: Electrolysis, is a method of using electric current to drive a non-spontaneous chemical reaction. In the production of the PVC, chlorine is produced by separating the chlorine and sodium ions of a salt brine using the method of electrolysis. The electrolysis of salt brine will produce hydrogen gas and chlorine gas.
2 Chlorination: Chlorination is the process of adding chlorine into ethene to produce ethylene chloride also commonly known as vinyl chloride. The chlorine is from the process of electrolysis of brine salt from previous process. In chlorination , chlorine is added to ethene to replace two H atom from the molecule without breaking the double bond in ethene to produce 1,2-dichloroethane. Iron (III) is used as catalyst in the process .
CH2=CH2 + Cl2 –> ClCH2CH2Cl
3 Thermal cracking(VCM Cracker):
The main purpose of this process is to obtain the chloroethene also known as VCM. This is done because VCM couldn’t be obtained by simple chlorination of ethene. Hence, this process is carried out to removed one atom of chlorine from 1,2-dichloroethane as well as recovering the carbon-carbon double bond to obtain VCM. Basically the process is being carried out with condition of 500 °C with pressure ranging from 15 atm to 30 atm. Under that condition, 1,2-dichloroethane decomposes to produce chloroethene (VCM) and hydrogen chloride.
(Prepared by Lim Chung Kin, 0902959)
(4 Quenching,5 cooling water ,6 purification)
Cracking furnace effluent must be quenched, or cooled rapidly, to keep coking at a minimum. Therefore, the hot effluent gases are typically quenched and partially condensed by direct contact with cold EDC in a quench tower. Alternatively, the hot effluent can first be cooled by heat exchange with cold liquid EDC furnace feed or by vaporizing boiler feed water (BFW) to produce high pressure steam in a transfer line exchanger (TLX) prior to entering the quench tower. This arrangement saves energy by decreasing the amount of fuel needed to fire the cracking furnace and/or steam needed to vaporize the feed.
Then it will undergo the Purification process. Water elimination in a VCM purification system is achieved through on condition that a separation of a liquid mixture which consist of water, hydrogen chloride, and vinyl chloride into a hydrogen chloride distillate stream and an essentially pure vinyl chloride product stream in distillation column; and a drying system is placed in fluid communication with the distillation column midsection at a connection point where the water reached sufficient concentration so that a water functional mass transfer flux from a withdrawn midsection stream into a drying agent is provided.
The temperature control in this column achieves EDC-water separation control. The VCM produced in the pyrolysis section is separated in the VCM purification section. In the HCL column, temperature control is used to distil HCL off the top of the mixed feed containing mainly EDC, VCM and HCL. The bottom product is fed to the VCM column, where the temperature is controlled to purify VCM as overhead product and the recovered EDC is recycled back to the EDC purification section
After the VCM purification process, it is ends up in the feed to the oxychlorination process. If acetylene is allowed to enter the oxychlorination reactor, the acetylene would be readily converted to perchloroethylene and other heavily chlorinated by-products, resulting in a significant HCL efficiency loss. Consequently, the HCL recycle stream is usually passed through a hydrogenation reactor to selectively convert the acetylene to ethylene, which makes more EDC downstream.
Hydrogenation is generally carried out in a fixed bed reactor packed with catalyst made from a precious metal on an inert support. Hydrogen is added to the feed in stoichiometric excess to ensure conversion of acetylene to ethylene. The reaction is temperature dependant, with lower temperatures being preferable to maximize conversion to ethylene. If the temperature is too high, a fraction of the acetylene may be further hydrogenated to ethane.
(Prepared by Hew She Luan, 0905291)
(Stripping, Centrifuging, Drying and Sieving Process)
7 Stripping: In all of the processes used to produce PVC, unreacted VCM is present at the end of the reaction. VCM is a carcinogenic substance and it’s removal from PVC is very important for both avoiding downstream emission and for recycle purpose. Superheated steam is injected into the polymerization product in the reactor. The steam causes unreacted VCM to vaporize making it easy to remove. The temperature of the steam injected into the polymerization product should be 180 while the pressure should be 10 bar.
8. Centrifuging: During this step, PVC is separated from VCM. The water to the inlet of the centrifuge is filtered to prevent PVC from being contaminated by impurities in the water. Nexis T filters rated at 10m are recommended to filter the water.
9. Drying: Most of the water is removed when the slurry passes through the centrifuge. A damp ‘cake’ of polymer leaves the centrifuge and is conveyed into the fluid bed dryer. Here, the remaining water contained in the porous grains evaporates as a stream of heated air bubbles through the polymer powder. In order to minimize the emissions, the moist air is wet-scrubbed before discharge into the atmosphere.
After the drying process, the PVC will go through sieving process where the PVC is separate into different sizes for further processing.
(Prepared by Cody Yip Jun Kit, 10UEB00894)
(Storage and Handling, Control Room and Polymerization)
11. Storage and Handling
VCM must be stored in a tightly closed container in a cool, well ventilated area, away from direct sunlight, heat and incompatible materials .VCM can be stored in steel tanks at ambient temperature. The drums must be equipped with self closing valves, flame arresters and pressure vacuum. Consider installation of leak detection and alarm for storage and use area. VCM should not be stored below ground level.
12. Control Room
A Control Room is the room where pumps, fans, blowers, mixers, mills and centrifuges are controlled by variable speed drives and soft starters. Minicomputers are
used to control chemical reactors in the PVC production process.
Computer control can bring advantages to a batch process, closer control of the process, major gains in safety and the opportunity to use larger, more efficient processing equipment.
Under manual control, a polymerization cycle might take about 14 hours but computer control can cut this time to about 8 hours. Computer control also offers substantial gains in accuracy and safety. A typical computer controlled reactor stands about six stories tall and hold 30,000 to 50,000 gallons. While in manually controlled plants, each reactor’s capacity is between 2,000 and 7,000 gallons. Computer control enables PVC plants to meet new OSHA standards, effective April 1, 1976, that will limit the exposure of workers to VCM vapors.
VCM vapor is a known human carcinogen. If inhaled or absorbed through the skin, it may be harmful. VCM vapors may be a reproductive hazard.
The process of polymerization links together the vinyl chloride molecules to form chains of PVC. The PVC produced in this way is in the form of a white powder. This is not used alone, but blended with other ingredients to give formulations for a wide range of products.
In the polymerization process practically all of the VCM is processed into the inert polymer chains that make up the PVC plastic. It is possible for extremely low levels of any residual depolymerised VCM to remain in the polymer and eventually migrate into food from PVC packaging, but only at levels.
Polymerization of PVC is divided into 2 types which is emulsion polymerization and suspension polymerization. Emulsion polymerization involves the polymerization of monomers in an aqueous medium containing surfactant and a water soluble initiator, producing PVC lattices. PVC lattices are colloidal dispersions of spherical particles, ranging in size between 0.1 and 3.0 Î¼m. Most PVC lattices are spray dried and then milled to obtain fine powders, made up of agglomerates of latex particles. When mixed with plasticizers they disperse readily to form stable suspensions. During mixing most of the agglomerates are broken down into the original latex particles. Such dispersion of fine particles in plasticizers are known as plastisols or pastes, and the powder is called dispersion or paste polymer. The surfactant layer around the particle surface prevents their adsorbing the plasticizer at room temperature so they can be used as liquids and may then be spread on to fabric or other substrates, poured on molds, or deposited on formers to produce flooring, wall covering, artificial leather, balls, toys, or protective gloves. There are other grades of PVC polymers, produced by emulsion polymerization, that do not form plastisols and that are used as blends with suspension PVC grades for extrusion application or in the manufacture of battery separator plates. These so-called emulsion polymers are of only minor economic interest. Sales in latex form are very limited; lattices are used in water-based paints, printing inks, and impregnated fabrics.
(Prepared by A. Srinyanavel 0904742)
(Packing and dispatch, compounding, converting and recycling)
14. Packing & dispatch:
In this process, soft PVC is packed on a semi-automatic snaking machine or manually, depending on the size, shape, and length and intended use of final product. The length of the roll cut on a stumble varies for fix packages form 10m to 100 m. However, other lengths are also obtainable upon appeal. Rolls are provided with 3 binding strips and marked with market’s badges. Some soft PVC sizes are packed into polyethylene foil to provide appropriate security against incidental scratch or corrosion of their functionality.
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15. Compounding: This process involves storage, conveying, metering, mixing, and cooling. All these operations occur prior to the actual melt compounding. The distribution becomes harder because the filler loading level is increased and the surface area of the mineral filler increases. The surface area increases rapidly due to the particle size decreases. These are important steps in the process that can affect the quality of PVC. If these requirements are not met completely, the final product’s physical properties will be affected.
This process is either makes final PVC products for sale or makes components for further uses. Different additives like stabilisers and plasticisers need to be added to PVC resin to create a ‘compound’ that meets the requirement of the final product and of the processing technology to be used. Compounding may be carried out by the converters or by separate ‘compounders’ who supply ready-made blends prepared for processing. The PVC compound is then ‘converted’ by processes such as extrusion, moulding and calendaring.
Polyvinyl Chloride can be reused; however the purity of the material tends to degrade with each time of reuse cycle. In addition, the separation of the different additives and compounds forming the plastic makes recycle a difficult process.
The biggest problem with PVC recycling is that it is difficult to automate the sorting of plastic waste, and so it is labor-intensive. There are three ways of PVC recycling: mechanical recycling, mechanical recycling for mixed plastics and feedstock recycling.
(Prepared by Cheah Kai Mun, 0904128)
Role of chemical engineer in petrochemical industry
Beneath all of the general responsibilities listed above, a petrochemical engineer must engage in numerous specific duties on a daily basis. The first duty which the petrochemical engineer is responsible for completing is research. The petrochemical engineer must take careful steps to ensure that what they are looking to manufacture and how they are looking to manufacture a product is the right avenue to pursue. The way to resolve this issue is by doing a lot of research on a variety of topics relating to petrochemical engineering.
The petrochemical engineer is also responsible for designing a variety of items and this is a very important duty which they must complete. A petrochemical engineer must design various items such as measurement and control systems, petrochemical manufacturing equipment and petrochemical manufacturing processes. This is a major duty on the part of the petrochemical engineer and one which must be carried out with preciseness at all levels and stages.
A petrochemical engineer must also engage in a wide array of analyses. The things which the petrochemical engineer must analyze include test data, engineering design, design problems and research findings. The petrochemical engineer must take painstaking measures to adequately analyze these items as the outcome of the project could very well depend on the analysis which is undertaken by the petrochemical engineer.
One who is an engineer must develop certain procedures and policies as well so that there will be smooth operations all the way around the board. Various procedures and policies such as safety procedures, data tables and employment policies may all be in the hands of the petrochemical engineer. A senior level petrochemical engineer will have more to do with regard to developing policies and procedures within the company orcorporation.
The preparation of multiple reports is also in the hands of the petrochemical engineer. The petrochemical engineer must prepare data which specifically details the findings of certain tests and evaluations. These reports can be text or tables depending on the type of report which is needed.
A petrochemical engineer will also deal with other individuals a great deal. The reason for doing so is to relay the results and findings as well as oversee other petrochemical engineers and related workers in their field. From time to time, petrochemical engineers must lecture to their peers and the general public regarding their job and role in society.
The Skills/Knowledge required by the engineer
In the oil and natural gas industry such as PVC manufacturing industry, the Petrochemical Engineer is playing a important role. With all the products derived from crude oil it is practically impossible to imagine a world without them.
Act as a petrochemical engineer, several skills and knowledge are needed. Petrochemical engineers should be expert in analytical things. They need constantly putting their creativity to work, efficiently and on a large scale, transforming combinations of elements of matter, synthesizing new materials. Besides, it is important to determine the most effective processes for normal production. For example, Design and develop newest and enhanced processes and equipment for converting the raw materials into products by using computers to simulate and control such processes.
Other than that, creative and innovative thinking with excellent problem solving skills is important to a petrochemical engineer. In order to have an organized and high quality products being designed, engineers should always troubleshoot environmental problems in industrial processing and manufacturing plants. Just in the same way, efficient, safe and environmentally responsible plant operations needed to be ensured. Moreover, planning, organizing, and prioritizing tasks skills across multiple projects are needed by an engineer.
They acquire excellent both spoken and written, communication skills, and cooperate well in teams with people from different backgrounds and disciplines. Engineers, technicians, supervise technologists, and other involved in related activities. Additionally, participates aggressively in new product introduction are motivated, including influencing the design of the product to ensure manufacturability and quality conformance, testing the dependability of prototypes and managing the alteration into production.
Applying mathematical and scientific principles are needed too. Some of the processes such as catalytic cracking is developed by Petrochemical engineers to break down the complex organic molecules found in crude oil into much simpler molecules.
In a nutshell, chemical engineers need to possess skills, knowledge and experience in order to make the conversion of raw materials that enter the reactor into a useful product that leaves the reactor a success as well as minimizing the damage done to the environment. PVC production is still in demand worldwide even though everyone realizes that PVC takes a long time to decompose. However, the production of PVC will not be stopped as other industries still rely on plastics to manufacture or to pack their products. The industrial method to produce PVC involves 17 processes according to our group research and among the 17 processes some actually emit harmful materials or gases as a byproduct that causes damage to the environment. However, these processes must be made as environmentally friendly as possible to produce PVC without damaging the environment.
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