Production of renewable bio-energy by pyrolysis based on waste plastic

By:Mohannad Al-Qatanani (1037890)Bilal Al-Ghwairi (1035986)Yasser Siam Zaidan (1034780)Ola Adnan Hasan (1034791)

Supervised By: Dr. Issa Etier

Department of Electrical Engineering Hashemite University

2014-1015

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Table of content1.Introduction……...…………………………………………………………………...61.1 Objectives……………………………………………………………………………....61.2 Facts………………………………………………………………………………….....61.3Strategy………………………………………………………………………………….71.4 How plastic are made………………………………………………………………......71.5 Types of plastic……………………………………………...………………………….81.6 Plastic wastes problems………………………………………………………………...81.6.1 Plastic wastes Effect in the environment…………………………………………......91.6.2 Plastic problem in Jordan……………………………………………………..……..111.6.3Importanceof plastic recovery………………………………………………………..12301.7 Solutions of Waste Plastic………………………………………………………….....14 1.7.1 Recycling plastic…...…………………………………………………………….14 1.7.2 Energy Conversion or Degradation of Plastic…………….……………….…….151.8 Energy Conversion VS. Recycling………………………………………..…..16

2.Degradation Technics……..…….………………………………………………...17 2.1 Thermal degradation…….…………………………………………………………….17 2.2 Pyrolysis types………………….……………………………………………………..19

3. Design……...………………………………………………………………………….203.1 Electrical design………………………………………………………………….…....203.1.1 Sizing……………………………………………………………………………...…21 3.1.2Equipments……………………………………………………………………....22 3.1.3 Wiring and connections…………………………………………………………22 3.1.4 Feasibility……………………………………………………………………….233.2 Mechanical design…….……………………………………………………………....24 3.2.1 Equipments……………………………………………………………………...24 3.2.2 Design of the reactor…………………………………………………………....24 3.2.3 General characteristics………………………………………………………….25 3.2.4 Typical applications…………………………………………………………….26 3.2.5 Physical property of material…………………………………………………...26 3.2.6 Stress calculation………………………………………………………………..28 3.2.7 Thermocouple…………………………………………………………………..30 3.2.8 Pressure gauge…………………………………………………………………..30 3.2.9 Pressure state……………………………………………………………………31 3.2.10 Insulation……………………………………………………………………....32 3.2.11 Main characteristics and specifications………………………………………..33

4. Conclusions………………………………………………………………………..…355. Recommendation…………………………………………………………………...35References……………………………………………………………………………….36

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LIST OF FIGURES

Figure 1-1: Waste plastic...............................................................................................9Figure 1-2: Wastes of plastic in oceans.........................................................................10Figure 1-3: The Ghabawi landfills................................................................................12Figure 1-4: Waste process.............................................................................................15Figure 2-1: Thermolysis process...................................................................................18Figure 3-1: Electromechanical design parts……………………………………………20Figure 3-1: Electrical wiring…………………………………………………………...22Figure 3-3: Dimension of shank………………………………………………………..28Figure 3-4: Thermocouple types………………………………………………………..28Figure 3-5: Thermocouple Emf vs Temperature….………….………………………...28Figure 3-6: Pressure gauge……………………………………………………………..29Figure 3-7: The relief valve…………………………………………………………….30Figure 3-8: Reactor design……………………………………………………………..32Figure 3-9: 2D mechanical design……………………………………………………..33Figure 3-10: 3D mechanical design……………………………………………….…...34

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LIST OF TABLES

Table 1-1: Types of plastic and some uses………………………………….……………..8Table 1-2: Energy Conversion VS. Recycling……………………………………………16Table 3-1:Temperature for insulations……………………………………………..……..31

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Abstract:

Plastic wastes from milk containers, soft drink bottles, plastic wraps, plastic flatware, etc. have been successfully converted into fuel. Two approaches for the conversion of waste post consumer plastic into fuel have been investigated: (1) muffle furnace to reactor liquefaction system; (2) direct liquefaction system. Majority of used plastics are derived from ethylene, propylene, butadiene and benzene. Waste plastics are plastics that are used by the people in their daily life. It is collected from outside and city municipalities. Some of them are coded and rests are non-coded. A developed process discussed in this paper works with most of the waste plastic, both coded and non-coded. The plastics are heated up at 120-380 °C temperature to melt. The gaseous vapor is then condensed into liquid fuel.

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CHAPTER 1: INTRODUCTION

Plastics play an important role in almost every aspect of our lives. Plastics are used to manufacture everyday products such as beverage containers, toys, and furniture. The widespread use of plastics demands proper end of life management. Plastics make up almost 13 percent of the municipal solid waste stream, a dramatic increase from 1960, when plastics were less than one percent of the waste stream. The largest amount of plastics is found in containers and packaging (e.g., soft drink bottles, lids, shampoo bottles), but they also are found in durable (e.g., appliances, furniture) and nondurable goods (e.g., diapers, trash bags, cups and utensils, medical devices).

1.1 Objectives:

A) Recovery of Plastic will decrease the water/air rate of pollution since as what mentioned before plastic is a hardly-dissociated (durable) Material , And it’s a part of saving our planet.

B) Recovery of Plastic will help us find new untraditional oil resources , in order to reduce the usage of usual energy resources.

C) This project ends with an awareness plan that we have put for people to help them through the recycling plan by categorizing their waste, so that helping in plastic recovery and also in recycling other materials.

1.2 Facts:

32 million tons of plastic waste was generated in 2012, representing 12.7 percent of total MSW.

In 2012, the United States generated almost 14 million tons of plastics as containers and packaging, about 11 million tons as durable goods such as appliances, and almost 7 million tons as nondurable goods, such as plates and cups.

Only 9 percent of the total plastic waste generated in 2012 was recovered for recycling.

In 2012, the category of plastics which includes bags, sacks, and wraps was recycled at about 12 percent.

Plastics also are found in automobiles, but recycling of these materials is counted separately from the MSW recycling rate.

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1.3 STRATEGY:

1.3.1 Stage one:

To apply the theory:

Starting with defining our target (waste plastic ) with some facts and numbers to realize the volume of the problem .In this stage we studied the chemical properties of plastic ,codes, and effect on the pyrolysis mixture, the advantage of plastic degradation over recycling ,ending with building a simple pyrolysis prototype based on conventional heating method. (burning gas) externally , discussing the sustainability , reliability , and the feasibility of this kind of systems.

1.3.2 Stage two: (graduation project)

The electrical design of the system :

Depending on stage-one-results ; mainly in this stage we are going to design clean pyrolysis process -no fuel burner in producing heat with an electrical system using conventional heating sources like simple electrical resistance to provide enough power for heating in this technology ,Ending with building a simple prototype.

1.3.3 Stage three :( The vision )

Transform the system into totally clean energy processusing solar energy (concentrated solar towers ) to transform huge amounts of plastics and other bio-mass into useful fuel.

1.4 How Plastics Are Made:

Plastics can be divided into two major categories: thermosets and thermoplastics.

A thermoset solidifies or “sets” irreversibly when heated. They are useful for their durability and strength, and are therefore used primarily in automobiles and construction applications. Other uses are adhesives, inks, and coatings.

A thermoplastic softens when exposed to heat and returns to original condition at room temperature. Thermoplastics can easily be shaped and molded into products such as milk jugs, floor coverings, credit cards, and carpet fibers

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1.5 Types of plastic :

Considering plastic waste as our target in SWM we could know more about

It and table [ 1-1] shows the codes of plastics and there description

Table 1-1: types of plastic and some uses

1.6 Plastic Waste Problems :

Packaging is the largest and most rapidly growing category of solid waste. More than 30% of municipal solid waste is packaging, and 40% of that waste is plastic. Plastics never biodegrade; instead, plastic goes through a process called photo degradation, in which sunlight breaks it down into smaller and

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Number Acronym Full name Uses1 PETE/PET Polyethylene

TerephthalateSingle use plastic bottles, Peanut butter containers, Salad dressing bottles.

2 HDPE High-Density Polyethylene

Milk cartons, Some Detergent and Shampoo

bottles, Grocery bags3 PVC Polyvinyl Chloride Piping, shower curtains,

Lawn Furniture, Some detergent and shampoo

Bottles4 LDPE Low-Density Polyethylene Squeezable bottles, Plastic

bags, Six pack rings5 PP Polyethylene Bottles caps, Some food

containers, Car parts6 PS Polystyrene Plastic utensils, Packaging

peanuts, Styrofoam7 OTHER Other/Miscellaneous 5 Gallon water containers,

some food containers, DVDs

smaller pieces until only plastic dust remains. Plastic does not disappear – even as dust it persists for centuries, wreaking havoc in ecosystems. Given its lifespan, the quantity of plastic waste we throw away is deeply concerning. Plastic waste has accumulated to the point where degraded plastic pieces of the central North Pacific outweigh surface zooplankton by a factor of six to one.

As shown in fig.[1-1],Plastic pollution involves the accumulation of plastic products in the environment

that adversely affects wildlife, wildlife habitat, or humans. Many types and forms of plastic pollution

exist. Plastic pollution can adversely affect lands, waterways and oceans. The prominence of plastic

pollution is correlated with plastics being inexpensive and durable, which lends to high levels of plastics

used by humans [1].

Figure 1-1: Waste plastic

(U.S. Environmental Protection Agency. Municipal Solid Waste Generation, Recycling and Disposal in the United States: Facts and Figures 2007)

1.6.1 Plastic wastes Effect in the environment :

1.1 Land

Chlorinated plastic can release harmful chemicals into the surrounding soil, which can then seep

into groundwater or other surrounding water sources and also the ecosystem. This can cause serious

harm to the species that drink this water.

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Landfill areas are constantly piled high with many different types of plastics. In these landfills, there are

many microorganisms which speed up the biodegradation of plastics. Regarding biodegradable plastics,

as they are broken down, methane is released, which is a very powerful greenhouse gas that contributes

significantlytoglobal warming.

1.2 Oceans

Nurdles are plastic pellets (a type of microplastic) that are shipped in this form, often in cargo ships, to

be used for the creation of plastic products. A significant amount of nurdles are spilled into oceans, and

it has been estimated that globally, around 10% of beach litter is nurdles.  Plastics in oceans typically

degrade within a year, but not entirely, and in the process toxic chemicals such as bisphenol

A and polystyrene can leach into waters from some plastics. Polystyrene pieces and nurdles are the most

common types of plastic pollution in oceans, and combined with plastic bags and food containers make

up the majority of oceanic debris. In 2012 as shown in fig1.2, it was estimated that there was

approximately 165 million tons of plastic pollution in the world's oceans[3].

Figure 1-2: Wastes of plastic in oceans

1.3 Effects on animals

Plastic pollution has the potential to poison animals, which can then adversely affect human food

supplies. Plastic pollution has been described as being highly detrimental to large marine mammals,

described in the book Introduction to Marine Biology as posing the "single greatest threat" to

them. Some marine species, such as sea turtles, have been found to contain large proportions of plastics

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in their stomach. When this occurs, the animal typically starves, because the plastic blocks the animal's

digestive tract.Marine mammals sometimes become entangled in plastic products such as nets, which

can harm or kill them.

Over 260 species, including invertebrates, have been reported to have either ingested plastic or become

entangled in the plastic. When a species gets entangled, its movement is seriously reduced, therefore

making it very difficult to find food. Being entangled usually results in death or severe lacerations and

ulcers.It has been estimated that over 400,000 marine mammals perish annually due to plastic pollution

in oceans.In 2004, it was estimated that seagulls in the North Sea had an average of thirty pieces of

plastic in their stomachs.Marine plastic pollution can even reach to birds that never has been at the sea.

Parents can deliver junk food to their nestlings[4].

1.4 Effect on human

Plastics contain many different types of chemicals, depending on the type of plastic. The addition of

chemicals is the main reason why these plastics have become so multipurpose; however this has

problems associated with it. Some of the chemicals used in plastic production have the potential to be

absorbed by human beings through skin absorption. A lot is unknown on how severely humans are

physically affected by these chemicals. Some of the chemicals used in plastic production can

cause dermatitis upon contact with human skin. In many plastics, these toxic chemicals are only used in

trace amounts, but significant testing is often required to ensure that the toxic elements are contained

within the plastic by inert material or polymer [3].

Today, plastics accumulate in garbage dumps and landfills and are sullying the world's oceans in ever-greater quantity. And plastics and their additives aren't just around us, they are inside virtually every one of us- present in our blood and urine in measureable amounts, ingested with the food we eat, the water we drink and from other sources [4].

.1.6.2 Plastic problem in Jordan:

Random dumping and burning of plastic garbage, which constitutes a fifth of the Kingdom’s solid waste, are negatively affecting the environment and public health, ‘said a Jordanian official’.Rising population in an increasingly urban setting helps speed the use of disposable bottles, bags and product packaging.According to the experts and workers in the plastic fields: Around 2.13 million tons of waste, and 18,000 tons of medical and hazardous materials, are generated annually in Jordan and they add that waste increases by 3 per cent in Jordan every year.

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Meanwhile, Thomas Stocker, co-owner of a local company, said during the seminar that 17 per cent of solid waste in Jordan is plastic and that the waste management sector in Jordan remains untapped, noting that there is potential and opportunities in turning plastic waste into a source of income and jobs [2].

1.6.2.1 Environment Ministry indicate alarming plastic pollution statistics for Jordan:

Although Jordan is not considered as an industrial country it has a huge market in consumption which means huge numbers in solid waste .

Jordan generates 6 million tons of solid waste every year, 20% are plastics Each Jordanian generates on average 2.2 pounds of solid waste daily Jordanians use an average 1.5 plastic bags per day that’s 500 plastic bags each, yearly! 3 billion plastic bags  are used in the country annually, only 20% find their way to landfills and

2,200 tons of waste are collected daily in the capital and sent to the Ghabawi landfill see fig 1.3 to evaluate the problem [4].

Figure 1-3:TheGhabawi landfill, where trash is compressed

into cells between alternate layers of soil

1.6.3 Importance of plastic recovery

With the increasing human population the needs for the people also increases. But the point of concern is that are there enough natural resources to service all your needs ? . What if these We resources finish ?, this is one thing we need to ponder upon. . need to start recycling waste to converse our natural resources One of these waste is Plastic .

We can divide the importance of our project to two kinds according to the benefits for each one :

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1.6.3.1 Benefits for environment :

By recovery of plastic material we can reduce air pollution as well as water pollution. Plastic factories produces large amount of smoke when it is producing plastic material at the same time, if we don’t have proper waste disposal system those waste cause emissions will pollution.

For plastic wastes , Plastics are durable: their toughness and inertness are what make them so useful. Unfortunately, they're so durable that they break down very slowly in a landfill. When plastics find their way into the environment "into the ocean, for example" they can break down more quickly, but they still take a long time to biodegrade; a plastic bottle may take a century to break down, for example, while a plastic beverage holder could take four centuries. So that recovery plastic is very important to reduce pollution and save our environment.

The Environmental Protection Agency is on record saying that established waste-to-energy facilities generate electricity with “less environmental impact than almost any other source of electricity.”[6]

1.6.3.2 Benefits for energy :

Recycling and recovery of plastic minimizes the need for raw materials so that the rainforests can be preserved. Great amounts of energy are used when making products from raw materials. These methods require much less energy and therefore help to preserve natural resources.

Manufacturers make plastics from crude oil derivatives or natural gas, so making more plastic consumes an increasing amount of nonrenewable fossil fuel. The amount of oil needed to produce a plastic bottle is enough to fill a quarter of the bottle On average, according to the Stanford University recycling center, 1 ton of recycled plastic saves 16.3 barrels of oil. Recovery of plastic cuts back on oil consumption, thereby helping to extend the lifespan of our remaining fossil fuel reserves.[6]

1.7 Solutions of Waste Plastic :

Plastic waste has no place in our day life so solutions will so considerable and environmentally so

efficient .

Types of solution:

A) Recycling plastic.

B) Energy conversion or degradation of plastic.

1.7.1 Recycling plastic:

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Plastic recycling is the process of recovering scrap or waste plastic and reprocessing the material into useful products, sometimes completely different in form from their original state, but not all types of plastic can be recycled; for instance, “PVC”.

Why are some plastic recyclable and other not??

Whether or not a plastic is recyclable depends on its chemistry.

In some cases, such as (PVC), the resin is very difficult to recycle. Therefore..it is usually not collected.

The reason why some plastic are only recyclable sometimes is because These plastic usually have less recycling efficiency, meaning that the recycling process is either labor intensive or that the recycled products are not of very high quality.[6]

1.7.2 Energy Conversion or Degradation of Plastic :

Thermal conversion process was applied with three types of waste plastic mixture and waste plastics mixture to liquid hydrocarbon fuel production in present of oxygen under laboratory Labconco fume hood without adding any kind of catalyst. Utilization of the process described can reduce the impact of waste plastics significantly. Thermal decomposition of the most common plastics such as high density polyethylene (HDPE), polypropylene (PP) and polystyrenes (PS) has been conducted to produces a mixture of hydrocarbons. The thermal process applied of mixed waste plastics using a steel reactor at 25- 430Co has been investigated. The reactor was connected with standard condensation unit with water circulator system. Waste plastics are broken down into shorter chain hydrocarbon compounds from long chains during the thermal conversion process without adding catalyst or chemical. Produced fuel was analysis by using GC/MS, FT-IR and DSC and from GC/MS analysis result showed hydrocarbon chain range C3 to C28 into fuel and produce fuel can be use as feed stock refinery or power plant for electricity generation or can use for internal combustion engine.see fig 1-4.

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Figure 1-4:Waste Process

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1.8 Energy Conversion VS. Recycling:

Energy recovery is much more better than recycling that saves money and time and efforts in mass

waste management .see table 2-2 that shows how energy recovery better than ordinary recycling.

In terms of Recycling Plastic Energy Recovery from Plastic

Types of Plastic Not all kinds of plastic can be recycled ( as we have seen in the

table above ) so they need process.

Almost all kinds of plastic can be recovered into energy.

Sorted Plastic must be carefully sorted to be the exact type

Can be recovered mixed items of plastic

Effects on the Environment

Recycling plastic may be toxic. a. Pollute the environment.b. Harmful to our bodies.

The energy recovery process is friendly to the environment. (no CO2 emissions )

Effort and Time It needs a high effort and time It needs less effort and time than the Recycling plastic.

Costs A-It needs manufacturers and communities must be able to cost effectively.(Capital Cost)

B- It may be very expensive and not easy. (Running Cost)

A-It needs manufacturers and communities must be able to cost

effectively.(Capital Cost)B-It is much more cheaper than recycling

plastic. (Running Cost)

Table 1-2:Energy Conversion VS. Recycling

We notice that the energy recovery from plastic is :

A) Friendly to the environment.

B) Less cost comparing with plastic recycling.

C) A new source of energy.

So it could be the 21st century’s wealth of energy and can be considered asRenewable Energy.

CHAPTER 2: Degradation Technics

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Plastics have become an indispensable ingredient of human life. Their enormous use is a matter of great environmental and economic concern, which has motivated the researchers and the technologists to induce different degrees of degradations in the plastic. These degradations can be induced in a better way if their mechanistic implications are properly understood. A better understanding of the mechanism for these degradations is also advocated in order to facilitate the proper use of the alternative waste disposal strategies.

In view of the facts concerning the plastic degradation, we have discussed various types of polymeric degradations along with their mechanisms, which include:

Thermal degradation Photo-oxidative degradation Ozone-induced degradation Mechanochemical degradation Catalytic degradation and biodegradation

2.1 Thermal degradation (Thermolysis) :

Thermolysis is the treatment of plastic solid waste(PSW) in the presence of heat under controlled temperatures without catalysts .

Thermolysis processes can be divided :

1. pyrolysis (thermal cracking in an inert atmosphere)

2. gasification (in the sub-stoichiometric presence of air usually leading to CO and CO2 production)

3. hydrogenation (hydrocracking)

Thermal degradation processes allow obtaining a number of constituting molecules, combustible gases and energy, with the reduction of landfilling as an added advantage.

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Figure 2-1:Thermolysis processes, current main technologies and their main obtained products

The pyrolysis process is an advanced conversion technology that has the ability to produce a clean, high calorific value gas from a wide variety of waste. The hydrocarbon content of the waste is converted into a gas, which is suitable for utilisation in either gas engines, with associated electricity generation, or in boiler applications without the need for flue gas treatment. This process is capable of treating many different solid hydrocarbon based wastes whilst producing a clean fuel gas with a high calorific value. This gas will typically have a calorific value of 22–30 MJ/m3 depending on the waste material being processed.

Pyrolysis provides a number of other advantages, such as (i) operational advantages, (ii) environmental advantages and (iii) financial benefits. operational benefit is that pyrolysis requires no flue gas clean up as flue gas produced is mostly treated prior to utilisation. Environmentally, pyrolysis provides an alternative solution to landfilling and reduces greenhouse gas (GHGs) and CO2 emissions. Financially, pyrolysis produces a high calorific value fuel that could be easily marketed and used in gas engines to produce electricity and heat.

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2.2 Pyrolysis types:

2.2.1 Fast pyrolysis:

Fast pyrolysis yields 60% bio-oil and takes seconds for complete pyrolysis. In addition, it gives 20%

biochar and 20% syngas

The essential features of a fast pyrolysis process are:

A) Very high heating and heat transfer rates, which require a finely ground feed.

B) Carefully controlled reaction temperature of around 500oC in the vapour phase.

C) Residence time of pyrolysis vapours in the reactor less than 1 sec.

D) Quenching (rapid cooling) of the pyrolysis vapours to give the bio-oil product.

Disadvantages:

1) High oxygen and water content of pyrolysis liquidsmakes them inferior to conventional hydrocarbonfuels.2) Phase-separation and polymerization of the liquids and corrosion.

2.2.2slow pyrolysis:

Averagely slow pyrolysis characteristics is not that far from fast pyrolysis but the main difference is that slow pyrolysis work as a slow operation with simple and easy sit up and cheap hard ware , in this project we tend to apply slow pyrolysis .

The slow and fast pyrolysis was studied in fixed-bed and fluidized bed reactors at different pyrolysis temperatures. The effects of reactor type and temperature on the yields and composition of products were investigated.In the case of fast pyrolysis, the maximum bio-oil yield was found to be about 44 wt% at pyrolysis temperature of 500 °C , whereas the bio yields were of 21 and 15 wt% obtained at 500 °C from slow pyrolysis . Both temperature and reactor type affected the composition of bio-oils. The results showed that bio-oils obtained from slow pyrolysis can be used as a fuel for combustion systems in industry and the bio-oil produced from fast pyrolysis can be evaluated as a chemical feedstock.

So We use the slow type because it’s suitable for our requirement.

Chapter 3: Design

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Design is separated into two parts :Design going to be separated into two fields as fig 3-1:

Figure 3-1: Electromechanical design parts.

3.1 The electrical design

Studies states that The pyrolysis is an endothermic process, studies states that typical energy consumption 4.0-5.7 MJ Kg-1 (Piskorz et al., 1999) averagely 4.85 MJ Kg-1

Which can be provided by 1.4 KWH Kg-1 electrical power , and in this case We have 7-kg-reactor which will consume almost 7*1.35 kwh = 9.5 kwh

But pyrolysis process needs gradually to higher temperature to achieve aimed results .And this take some time (expected time 4- 4.5) which means (2) kw coils .

And for better heat distribution we intend to use two coils in parallel , and single phase AC will be enough to achieve power requirements , The voltage 220v in Jordan , specs of the nichrome wire something around 1-1.5mm diameter wire will be used .

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Electro-mechanical Design

Electrical

Sensors and control

High voltage . Energy

supplier .

Mechanical

Used material in the design

The over all design of the system considering , pressure , temperature

Based on our power needs:

3.1.1 Sizing:

We calculate the wire resistance , and then determine the length needed .For example if the wire has 30 Ohms of resistance per meter and you need it to work at 1000w of power, then at 220 volts that would be 4.54 Amps, so you need to get the wire so long that its resistance will limit the current to 4.55A .

In other words :

If I have 220 volt voltage source , 30 ohm/m coil resistance , how long resistance coil I need achieve 1kw of power

We know that :

P = V*I

1kw (needed power)= 220V(single phase voltage source) * I

So : I = 4.55 A

And length of the coil that limit current to 4.55 A refer to basic role is :

V=I*R

220v =4.55 A * 30 ohm * required lengthRequired coil length = 1.6m

Or we can just limit the length of the coil and change the resistance /m of the coil .

And for this case mostly we are going to use :p= 1KW coil , L= 1.6 m , and resistance =48 ohm/m (the most suitable for this case)

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3.1.2Equipment:

1) Nichrome wire around 1-1.5mm diameter wire2) Digital thermostat controller3) Two solid state relays4)Tow variable resistance5)Thermo couple6) Wires

3.1.3 wiring and connections:

Here is how the electrical circuit would look like in your case of single phase current:

Figure 3-2: Electrical wiring

Single phase current will provide will provide 220 V volt voltage source coils are already sized to obtain 1 kw each .the digital thermostat is connected to a thermo couple combined with solid state controller to Interface and control temperature by controlling power coils , further more SSR may connected to a variable resistance for better current control approach .

We made calculations, it turns out that our device, as crude as it is with much room for improvement, can produce diesel fuel at a cost of 17 US cents a liter, that is when only plastic and electricity is considered. See fig 4-2 The next machine will probably use a liquid fuel burner to heat the reactor, this could lower the costs even more as it would then run on a small percentage of the produced fuel and also

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the produced gas would then be used more practically - burned along with the fuel to heat the reactor. Even now, if we would get the electricity from a diesel generator that runs on the produced fuel, it would consume about 20% of the produced fuel.[8]

3.1.4 Feasibility of the system:This study shows how much feasible is this process :

.The pyrolysis is an endothermic process, studies states that typical energy consumption 4.0-5.7 MJ Kg-

1 (Piskorz et al., 1999) ,

the expected amount for 1 Kg of plastic is almost 1 liter of diesel fuel (practical experiments made by some Japanese expertise )

and also it’s known that :1 litre of diesel fuel = 40MJ = 11.1kWh

( Beginner’s Guide to Energy and Power, Staffordshire University, UK, February 2011)

With simple calculation :

Produced energy – consumed energy (in pyrolysis process) = net output energy

40MJ – 4.3 MJ = 35.7 MJ Kg-1

output energy for 1 kg of waste plastic****The produced energy is almost 10 times used energy *****

The system is feasible

We have to state also that better condition-control may give better results and higherThe efficiency of the system for example: the core of the electrical pyrolysis process depends on( heating gradually in absence of oxygen ) so we can improve the processby better evacuating system of oxygen or using better heating control of the coils etc .

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3.2 The Mechanical design:

3.2.1 Equipments:

Reactor Thermocouple Pressure gauge Pressure state Heating coils

3.2.2 Design of the Reactor:

Due to high temperature and pressure the reactors materials must have high thermal resistance and

high strength to avoid strain and deflection in the material so we chose the steel as a material for the

reactor, the chosen alloy is AL-6XN and here some properties:

AL-6XN (UNS designation N08367) is a type of wieldable stainless steel that consist of

an alloy of nickel (24%), chromium (22%) and molybdenum (6.3%) with other trace elements such

as nitrogen.

The high nickel and molybdenum contents of the AL-6XN alloy give it good resistance

to chloride stress-corrosion cracking. The molybdenum confers resistance to chloride pitting that

produced from the PVC. The nitrogen content serves to further increase pitting resistance and also gives

it higher strength than typical 300 series austenitic stainless steels, and thereby often allows it to be used

in thinner sections. But because it is not available at the market as an alternative the 300 series will be

use.

3.2.3 General characteristics:

Most widely used molybdenum alloyed austenitic stainless steel. It is mainly used in applications for

handling the wide range of chemicals used by process industries, e.g. pulp and paper, textile, food and

beverages, pharmaceutical, medical, and in the manufacture of other chemical processing

equipment. This austenitic low carbon grade 4404 belongs to a group of chromium-nickel-molybdenum

grades. These grades are intended to provide improved corrosion resistance relative to the standard

chromium-nickel steel grades used in corrosive process environments. Modern stainless steels are today

easily produced with low carbon contents and the risk of chromium carbide precipitation has thereby

decreased significantly. Intergranular corrosion caused by chromium carbides is therefore rarely an issue

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nowadays, but stabilized grades, often type 1.4571, are still specified. Non-titanium-stabilized grades

generally have a better surface finish than titanium-stabilized grades.  Given their fully austenitic

structure, all these grades are non-magnetic in the annealed condition but may become slightly magnetic

as a result of phase transformation due to cold working or welding. The high nitrogen grades, i.e. 1.4406

and 1.4429 have except from an increased mechanical strength also a more stable austenitic structure

leading to a lower permeability in comparison to the other standard chromium-nickel-molybdenum

grades. • All-purpose grade • Enhanced corrosion resistance compared to standard Cr-Ni grades •

Excellent formability • Excellent weldability • Excellent impact strength.

3.2.4Typical applications:

The addition of molybdenum provides improved resistance to pitting and crevice corrosion in

environments containing chlorides or other halides.

These grades are used in applications for handling the wide range of chemicals used by process

industries, e.g. pulp and paper, textile, food and beverages, pharmaceutical, medical, and in the

manufacture of other chemical processing equipment. These grades are supplied with a wide range of

functional and aesthetic surfaces.

The chemical composition of specific steel grades may vary slightly between different national

standards. The required standard will be fully met as specified on the order.

The chemical composition is given as % by weight.

The mechanical properties of the available products are given in the table below.

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Properties of some materials

Corrosion resistance: The chromium-nickel-molybdenum standard stainless steels have a versatile

corrosion resistance and are suitable for a wide range of applications. The grades with molybdenum

content of 2.6 per cent have somewhat enhanced corrosion resistance compared to the grades with

molybdenum content of 2.1 per cent . For a more detailed description of their corrosion resistance

properties in different environments.

Corrosion resistance of material

Physical properties (according to EN 10088) are shown below.

3.2.5 Physical property of material:

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Heat Resistance : Good oxidation resistance in intermittent service to 870°C and in continuous service to

925°C. Continuous use of 316 in the 600-860°C range is not recommended if subsequent aqueous

corrosion resistance is important. Grade 316L is more resistant to carbide precipitation and can be used

in the above temperature range.

Welding : Excellentweld ability by all standard fusion methods, both with and without filler metals. Pre-

qualifies welding of 316 with Grade 316 and 316L with Grade 316L rods or electrodes (or their high

silicon equivalents). Heavy welded sections in Grade 316 require post-weld annealing for maximum

corrosion resistance. This is not required for 316L. Grade 316Ti may also be used as an alternative to

316 for heavy section welding.

Machining : PRODEC 316/316L is melted to a closely controlled chemistry and ladle treated to achieve

control of the composition, amount, size, shape, and distribution of the non-metallic inclusions(sulphides

and oxides) normally occurring within a standard stainless steel. These inclusions provide for chip

breaking and for reduced wear of carbide tooling at high machining speeds. PRODEC 316/ 316L

permits higher machining speeds, longer tool life, and superior part quality with reduced total cost for

finished parts.

3.2.6Stress Calculations:

Stress calculation is necessary for this kind of applications .

σ longtudinal=P∗Dm4∗t

σ hoop= P∗Dm2∗t

Design pressure = 7 bar = 709.1 kpa

Dm = 20 cm

From calculations and the available material in stock the thickness equal 3 mm

Eight eye bolts that hold the cover calculation:709kpa /8=88.6kpa see fig 3-3 .

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Figure 3-3: Dimension of shank

(¼ *1 is selected)

3.2.7Thermocouple:

Thermocouple types chart :

Figure 3-4: Thermocouple types

Figure 3-5: K type is selected because of its availability andlinearity over the desired region.

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3.2.8Pressure Gauge:

It must be high temperature pressure gauge

Figure 3-6:Pressure gauge

3.2.9Pressure state:

The relief valve (RV) is a type of valve used to control or limit the pressure in a system or vessel which

can build up by a process upset, instrument or equipment failure, or fire.

The pressure is relieved by allowing the pressurised fluid to flow from an auxiliary passage out of the

system. The relief valve is designed or set to open at a predetermined set pressure to protect pressure

vessels and other equipment from being subjected to pressures that exceed their design limits. When the

set pressure is exceeded, the relief valve becomes the "path of least resistance" as the valve is forced

open and a portion of the fluid is diverted through the auxiliary route. The diverted fluid (liquid, gas or

liquid–gas mixture) is usually routed through apiping system known as a flare header or relief header to

a central, elevated gas flare where it is usually burned and the resulting combustiongasessee figure 3-4

released to the atmosphere.[1] As the fluid is diverted, the pressure inside the vessel will drop. Once it

reaches the valve's reseating pressure, the valve will close. The blowdown is usually stated as a

percentage of set pressure and refers to how much the pressure needs to drop before the valve reseats.

The blowdown can vary from roughly 2–20%, and some valves have adjustable blowdowns.

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In high-pressure gas systems, it is recommended that the outlet of the relief valve is in the open air. In

systems where the outlet is connected to piping, the opening of a relief valve will give a pressure build

up in the piping system downstream of the relief valve. This often means that the relief valve will not re-

seat once the set pressure is reached. For these systems often so called "differential" relief valves are

used. This means that the pressure is only working on an area that is much smaller than the openings

area of the valve. If the valve is opened the pressure has to decrease enormously before the valve closes

and also the outlet pressure of the valve can easily keep the valve open. Another consideration is that if

other relief valves are connected to the outlet pipe system, they may open as the pressure in exhaust pipe

system increases. This may cause undesired operation.

Figure 3-7: The relief valve

5 bar pressure stat is required for safety to prevent failure in the system due to high pressure.

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3.2.10 Insulation:

The best high temperature insulations are aluminium oxide bricks, Glass wool, Stone wool and Ceramic

fiber wool :

Material Temp. °C

Al brick 300

Glass wool 230 - 26

Stone wool 700 - 850

Ceramic fiber 1200

Table 3-1: Temperature for insulations

Ceramic Fiber is produced from high purity aluminosilicate material through strictly controlled high

temperature furnace melting and fiberizing process. The fiber is white and odourless, suitable for high

temperature applications up to 2300°F.

4.2.11 Main Characteristics and Specifications:

Lightweight,  low thermal conductivity, high temperature stability, excellent handling strength, low heat

storage, thermal shock resistant, fire and flame proof, chemical resistant, compatible with most corrosive

chemicals, commonly used acid and alkali (exceptions are hydrofluoric, phosphoric acids and

concentrated alkalis).

Chemical Composition: Al2O3 + SiO2 >97% ( Al2O3 47%); Fe2O3< 1%

Fiber Diameter: 3 – 4.5 microns

Fiber Shrinkage (1800°F, 3h): < 3.5% 

Working Temperature :           1,800 °F. for Continuous Use, 2300 °F Maximum

Specific Heat (@2000°F):      0.27 Btu/lb °F 

pH Range: 2-12

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In figure 3-8 the reactor design is being shown that is done by auto inventor

Figure 3-8:Reactor design

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Figure 3-9: 2D mechanical design

33

Figure 3-10: 3D mechanical design

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4. Conclusions:

Pyrolysis is one of the most waste management efficient methods for waste plastics) , it saves more time , efforts and money than conventional recycling .

Pyrolysis is not only waste management process it’s although an unconventional source of energy . Pyrolysis seems to be the only way we can keep the irreplaceable industry of plastic alive by

refreshing the feed stock with wste plastic which means renewable feed stock independent of the oil availability world wide .

Practically Pyrolysis technology is very efficient , because output energy is way more than used energy in the process by nine times or more wich make it also feasible as source of energy .

Using pyrolysis technology in the (SWM) could reduce CO2 emission by 80% Comparing with ordinary methods like landfills or burning waste . Complexity of the system can be improved with more stages of preparation And modifications to accept several kind of bio mass like wood and good percentage of house

wastes. In Jordan we are in need of technologies like this one , specially, with the shortage of energy

sources and oscillation of fuel prices .

5.Recommendation:

This technology is highly recommended due to the problem of waste plastic which the whole world is facing nowadays, in Jordan the problem is deeper with shortage of energy sources and this technology will applied for the first time in middle east which means a regional market

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References

[1] Beginner’s Guide to Energy and Power, Staffordshire University, UK, February 2011

[2] Journal of Polymer Science Part C: Polymer Symposia

[3] A. András, N. Miskolczi and L. Bartha, “Petrochemical Feedstock by Thermal Cracking of Plastic Waste”, Journal of Analytical and Applied Pyrolysis, Vol. 79, No. 1-2, 2007, pp. 409-414.

[4] K. Adil and A. Y. Bilgesu, “Catalytic and Thermal Oxidative Pyrolysis of LDPE in a Continuous Reactor

System,” Journal of Analytical and Applied Pyrolysis, Vol. 78, No. 1, 2007, pp. 7-13.

[5] N. K. Ciliz, E. Ekinci and C. E.Snape, “Pyrolysis of Virgin and Waste Polypropylene and Its Mixtures with

Waste Polyethylene and Polystyrene,” Waste Management, Vol. 24, No. 2, 2004, pp. 173-181.

[6] J. Walendziewski, “Continuous Flow Cracking of Waste Plastics,” Fuel Processing Technology, Vol. 86, No.

12-13, 2005, pp. 1265-1278.

[7] J. Nishino, M. Itoh, H. Fujiyoshi and Y. Uemichi, “Catalytic Degradation of Plastic Waste into Petrochemicals

Using Ga-ZSM-5,” Fuel, Vol. 87, No. 17-18, 2008, pp. 3681-3686.

[8] B. Singh and N. Sharma, “Mechanistic Implications of Plastic Degradation,” Polymer Degradation and

Stability, Vol. 93, No. 3, 2008, pp. 561-584.

[9] http://steelfinder.outokumpu.com/v3/GradeDetail.aspx?OKGrade=4404

[10] http://www.aksteel.com/pdf/markets_products/stainless/austenitic/316_316l_data_sheet.pdf

[11] http://www.outokumpu.com/SiteCollectionDocuments/Datasheet-prodec-316-316l-hpsa-imperial-outokumpu-en-americas.pdf

[12] http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

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