Low Density Polyethylene (LDPE) Waste Plastic Transformation into Renewable Heavy Fuel Using Thermal Cracking

Low density polyethylene (LDPE) waste plastic was transformed into heavy fuel by using fractional distillation column process with liquefaction process. For experimental purpose two types of temperature profiles were used one for LDPE waste plastic liquefaction temperature and another one for fractional distillat ion column temperature. In this experiment liquefaction temperature ranges 100-420 °C and fract ional distillation temperature ranges 340-365 °C . LDPE waste plastic to heavy fuel production was performed without adding any kind of catalyst in presence of oxygen and without vacuum system. Different types of analytical equipment were used for produced fuel analysis purposed such as GC/MS, FT-IR and DSC. By using GC/MS analysis result indicates that LDPE waste plastic to produced heavy fuel hydrocarbon chain range C5 to C28 and light gas are also present and hydrocarbon range is C1-C4. FT-IR (Spectrum 100) analysis results indicate that produced fuel functional group has bands energy which is reflecting with calorific value. By using DSC analysis result showed produced fuel delta H value or enthalpy value. Produce fuel can be use for heavy equipment internal combustion engine or electricity generation or feed fo r feed stock refinery process.


Introduction
The decomposition of waste plastics into fuel represents a sustainable way for the recovery of the organic content of the polymeric waste and also preserves valuable petroleum resources in addit ion to protect ing the environ ment [1]. Municipal waste plastic represents about 8 wt% of the municipal solid waste and it generally consists of mixture of different kind of plastics: 40.5 wt% HDPE (High Density Po lyethylene) and LLDPE/ LDPE (Linear / Lo w Density Polyethylene ), 19.6 wt% PP (Polypropylene), 11.9 wt% EPS PS/ (Expandable Polystyrene / Polystyrene), 10.7 wt% PVC (Po lyviny l Chlo ride), 8.1 wt% PET (Po lyethylene t erep hthalat e), and about 5 wt % A BS (A cry lo n itrile Butadien Styrene) and 4.2 wt% other polymers [2]. This waste is difficu lt to be t reated o r recycled due to its complex nature and composition, structural deterioration of the poly meric co mponents and the contaminat ion with various organic, inorganic or bio logical residues. Pyro lysis is one of the best methods to recover the material and energy fro m poly mer waste, as on ly about 10% of the energy content of the waste plastic is used to convert the scrap into valuable hydrocarbon products [3]. The conversion of waste plastics into fuel represents a sustainable way for the recovery of the organic content of the polymeric waste and also preserves valuable petroleum resources in addition to protecting the environment [4]. The worlds limited reserve of coal, crude oil and natural gas places a great pressure on man kind to preserve its existing non-renewable materials. A mong the various recycling methods for the waste plastics, the feedstock recycling has been found to be a promising technique. There are a lot of research [4][5][6][7][8][9][10][11][12][13][14][15] in progress on the pyrolysis and utilization of pyrolysis products for various applications.
Thermal degradation of poly mer mixtures is more compl ex than the degradation of single po ly mers. Interactions can appear at high temperatures during decomposition in the polymer bulk, between the co mponents of the mixtu re and the low molecu lar weight products and free radicals that are formed by the scission of the poly meric chains. Due to these interactions, some poly mers can affect the quality of pyrolysis products even they are in small amount in polymer mixture. This is of very high interest especially when the pyrolysis oils have to pass some quality standards for use as feedstock or fuels [16]. ABS with flame retardant PVC and PET are heteroatom containing poly mers that create problems during thermal decomposition because bromine, ch lorine and nitrogen can remain as organic compounds in pyrolysis oils or can produce acid or to xic gases such as HCl, HBr, and HCN, NH 3 or polyhalogenated dibenzodio xins and dibenzofurans [17,18]. Therefore, the amount of these compounds has to be decreased as much as possible. Thermal degradation of A BS g ives oils with high content of benzene derivatives (toluene, ethylbenzene, styrene, cumene, andα-methylstyrene) but also containing significant amount of organic nitrogen as aliphatic and arom atic nitriles or nitrogen containing heterocyclic co mpounds. The amount and distribution of these compounds strongly depends on the thermal or catalytic conditions used for degradation [19,20].

Materials and Method
The raw materials were collection fro m Stamford city Wal-Mart store. Co llected raw material co mes with other plastic also such as LDPE (Low Density Polyethylene), HDPE (High Density Polyethylene), PP (Polypropylene) and PS (Po lystyrene). All plastics separated by manually fro m mixed plastics. LDPE waste plastic washed with soap and water by using sink because LDPE waste plastic was shopping or packaging bag and color was various types. Then washout LDPE waste plastic dried into room temperature by putting on the laboratory floor. After that LDPE waste plastic cut into small p ieces manually by using scissors. Small pieces LDPE waste plastic shopping bags were manually transferred into reactor chamber. Stainless steel reactor was setup under laboratory fume hood without vacuum system and in p resence of oxygen and it was fully closed system. Reactor was heated by electrical power and reactor capable temperature range was 25-500℃. For experiment purpose temperature rang was 100-420℃. Experimental set up were describe in Figure 1 and all number describe such as 1 = Low density polyethylene waste plastic, 2= Steel reactor, 3 = Fract ional distillation column, 4= 1 st fraction temperature, 5= 2 nd fraction temperature, 6=3 rd fraction temperature, 7= 4 th fraction temperature, 8= 5 th fraction temperature, 9= light gas cleaning system, 10= 1 st fraction fuel collection tank, 11=2 nd fraction fuel collection tank, 12=3 rd fract ion fuel collection tank, 13=4 th fract ion fuel co llection tank, 14 = 5 th fraction fuel collection tank , 15 = s mall pu mp, 16 = Teflon bag for light gas storage. In this experiment LDPE waste plastic was used only 1000 g m (1kg) and this experiment did not use any kind of chemical or catalyst. After setup the experiment started temperature was 100 ℃ and temperature increased up 420 ℃ gradually. In itial raw material LDPE plastic melting point temperature 120 ℃ and experimental temperature was 100 ℃. Fract ional colu mn temperature was setup by using electrical co il and temperature profile was for 1 st fractional at 40-65 ℃, 2 nd fract ional at 110-135 ℃, 3 rd fractional at 180-205 ℃, 4 th fractional at 260-285 ℃ and 5 th fractional at 340-365 ℃. In the experiment the main goal was to collect heavy fuel fro m LDPE waste plastic. By using this technology waste plastic converted into liquefaction fro m 100-420 ℃ and fractional co lu mn was setup for collection heavy fuel and other grade fuels. LDPE waste plastic melt due to heat applies then turn into liquid slurry when temperature increased gradually. Liquid slurry turn into vapor then vapor passed through into fractional distillat ion column surface and at the end vapor transform to fuel and the product was collected based on different fractional boiling point range wise. Negative boiling point vapor come out as light gas and this light gas hydrocarbon mixtu re of methane, ethane, propane and butane. Rest of all fractional fuels was collected according to their boiling point range like minimu m temperature to maximu m temperature wise such as 1 st fractional to 5 th fractional fuel. In diagram nu mber 14 is 5 th fractional fuel or heavy fuel and this fractional tower temperature was 340-365℃. During LDPE to heavy fuel production process didn't escape or leakage any gases materials into the environment and capture light gas was purified by using alkali solution then light gas transfer into Teflon bag by using small pump. Collected produced fuel was purified by using RCI technology provided RCI fuel purifier with centrifugal force and micron filter. In this experimental process heavy fuel production percentage was 18.1% and other fractional fuels was 73.9%. Remaining solid b lack residue was 3% and light gas was only 5% fro m total 1000 g m of LDPE waste plastic. In mass balance calculat ion fro m 1000 g m of LDPE waste plastic to heavy fuel conversion rate was 181 g m sample, rest of other grade such as gasoline, naphtha, aviation and diesel grade fuels conversion is total 739 g m sample, light gas generated fro m 1000 g m waste plastic to 50 g m sample and finally left over residue was 30 g m fro m total sample. Residue has also good Btu value and this Btu value more than 5000/ lb. Residue could be used as substantial coal, roof carpeting or road carpeting. Produced fuel density is 0.81 g/ ml. Total experiment runtime was 5-6 hours and input electricity was 7.89 kWh according to the laboratory scale. In this experimental process produced light gas could be use for reactor heating purposes and that will significantly reduce the production cost and increase the back up electricity stock.

Results and Discussion
Perkin Elmer GC/MS (Gas Chro matography and Mass Spectrometer) analysis of 5 th fract ional fuel/ heavy fuel ( Figure 2 and Table 1) hydrocarbon compound list is analysed based on their peak intensity. GC/MS chromatogram analysis is showing higher concentration level peak intensity. This fuel's fractional temperature is 340-365 ℃. Th is fuel is similar to fuel o il category. Chro matogram analysis starting compound is Cyclopropane, ethyl-(C 5 H 10 ) at retention time is 1.91 minutes. Fro m data table (Table1) we saw all hydrocarbon compounds are straight chain hydrocarbon compounds and some are branch chain hydrocarbon compounds are as well. Fro m the fuel we found alkane group and alkene group co mpound. Long into Renewable Heavy Fuel Using Thermal Cracking chain hydrocarbon compound showing at retention time 28.45 minutes and compound is Octacosane (C 28 H 58 ) and mo lecular weight is 394. In the fuel all hydrocarbon compounds contains heavy hydrocarbon and their derivatives as well as hydrocarbon range is C 5 -C 28      Perkin Elmer FT-IR (Fourier transform infrared spectroscopy, Spectrum 100 ) analysis of LDPE waste plastic to heavy fuel oil ( Figure 3 and Table 2) shows the following types of functional groups starting at wave number 3615.94 cm -1 , derived functional group is Free OH, wave nu mber 2939.68 cm -1 , 2730.52 cm -1 and 2673.36 cm -1 functional group is C-CH 3, wave nu mber 1821.11 cm -1 , 1716.58 cm -1 , and 1641.53 cm -1 functional group is Non-Conjugated, wave number 1606.19 cm -1 functional group is Conjugated. As well as wave number 1471.60 cm -1 and 1377.78 cm -1 functional group is CH 3 ,wave number 991.75 cm -1 and 909.18 cm -1 ,functional group is -CH=CH 2 and ultimately wave number 887.85 cm -1 functional group is C=CH 2 and wave nu mber 721.33 cm -1 functional group is -CH=CH-(cis    Figure 4) analysed by DSC (Differential scanning calorimeter) and measured the boiling point temperature and enthalpy value in this fuel. After analysis fuel sample we found onset temperature is 12.74 ℃, Peak temperature is 204.56 ℃ and peak height is 33.7054 mW . Peak height is represents the heat flow Endo up 40 % fro m total 100%. The graph showed area is 39734.821 mJ and enthalpy delta H value is 39734.8206 J/g. This produce fuel hydrocarbon compounds are heavier and making heavy fuel we used higher temperature profile in the fractionation process and temperature range was 340-365 ℃. Fifth (5 th ) fract ional or heavy fuel boiling starts from at 12.74 ℃ and end boiling temperature finished almost close to 300 ℃, because this fuel has heavier straight long chain hydrocarbon compounds like alkane or alkene co mpounds.
In Table 3 showed trace metal analysis result by using ICP fro m LDPE waste plastic to heavy fuel production. Solid black residue generated 3% fro m total initial feed. This residue was left over because plastic manufacturing company adding different types of additives fo r p lastic hard shape and thickness. This additive was come out or left over after fuel production process and this solid residue have also good Btu (Brit ish thermal

Conclusions
Thermal cracking with fract ional distillat ion process was performed with LDPE waste plastic and produced fractional heavy fuel without using any kind of catalyst. Two types of temperature were used for this experiment one was liquefaction temperature and another one was fract ional distillat ion colu mn temperature for LDPE waste plastic to heavy fuel generation. Produced fuel was analysis by using various types of equip ment such as GC/MS, FT-IR and DSC. GC/M S analysis result indicates that produced fuel has short chain hydrocarbon to long chain hydrocarbon compounds and starting short chain hydrocarbon compound carbon number is C5 and long chain hydrocarbon compound carbon number is C28. By using FT-IR analysis result showed also produced fuel functional group band energy. LDPE waste plastic to heavy fuel has alkane and alkene group compound which is aliphatic compound because in the initial raw material co mpound was only straight chain hydrocarbon compounds. Produced fuel could be use all heavy equipment engine or feed fo r feed stock refinery or feed for electricity generation. By using this established technology could be solve the LDPE waste plastic related environ mental p roblem and boost up the renewable energy generation fro m LDPE waste plastic.