The most important parameters of our apparatus:Steam cracking temperature up to 900 °CFeasible contact time: 0.1 - 0.8 secFeedstock: gasoline. gas oils. solid paraffinsCapacity range:max. 1.5 l/hReactor geometry: 2.54 cm diameter; 85 cm long

This apparatus is validated to steam crack complex mixtures: gasolines and gas oils. The olefin yields are in accordance with literature data and commercial practice.

Steam cracking of polyethylene (HDPE, LDPE) and polypropylene (PP)

The polymer samples were steam cracked in two stages

First stage: 300 to 500 °C

Steam cracking temperature: 770 to 860 °C

Contact time: 0.2 - 0.3 sec Steam/polymer mass ratio: 5-7

Batch process

The pyrogas composition of HDPE at different temperatures

0

20

40

60

80

800 830 860Temperature, °C

m/m

%

The pyrogas composition of PP at different temperatures

0

10

20

30

40

50

60

70

770 800 830Temperature, °C

m/m

%

Pyrogas composition of different polymers at 830 °C

0

10

20

30

40

50

60

70

HDPE LDPE LPPE PP800 PP830

m/m

%

Steam cracking of solid paraffins

30.850.355.956.957.8ETHYL+PROP

24095478416363Av. M, g/mol

7.114.015.112.315.4Propilene, m/m%

23.736.340.844.642.5Ethylene, m/m%

48.090.088.889.789.3Pyrogas, m/m%

0.460.340.460.460.46Water mass ratio

0.50.30.30.30.3Contact time, sec

830860830860830Temperature, °C

Gas oilGasolinedw6266dw5759dw5254

Distribution of carbon atom number of paraffins

0

5

10

15

20

19 29 39 49 59No. of carbon atoms

%

dw5254

dw5759

dw6266

Every sample was steam cracked at different conditions; the highest yields and the corresponding parameters are represented

1:1: water storage vessel water storage vessel

2:2: gasoline / gas oil storage vessel gasoline / gas oil storage vessel

3:3: water pump water pump

4:4: pump pump

5: 5: heatable storage vesselheatable storage vessel

6: 6: heatad pumpheatad pump

7:7: water preheater water preheater

8:8: preheater and mixer furnace preheater and mixer furnace

9:9: three sectro furnace three sectro furnace

10:10: jacketed and coil water cooler jacketed and coil water cooler

11:11: water cooled separator water cooled separator

12:12: cryostat cooled separator cryostat cooled separator

13:13: tube-in-tube gas cooler tube-in-tube gas cooler

connected to cryostatconnected to cryostat

14:14: adsorber adsorber

15:15: gas meter gas meter

16:16: T-branch to sampling T-branch to sampling

17:17: hydrocarbon tube preheater hydrocarbon tube preheater

Recycling of polyolefins in steam-crackingRecycling of polyolefins in steam-crackingAttila Pintér, Tungler Antal Dr., Lajos Nagy dr., László Vida dr., János Kerezsi

Department of Chemical Technology,Budapest University of Technology and Economics

Budapest, HungaryE-mail: pinter.attila@freemail.hu

Steam cracking of low polymerisation grade polyethylene (LPPE)

LPPE is soluble in hot gas oil at 120 °C. The viscosity of the mixture is low enough to pump.The mixture can be steam-cracked with good olefin yield: •the mixture produces the same amount of olefin as the gas oil at same conditions•no coking observed inside the reactor

‘A’: Gas oil

58,864,154,753,957,853,952,552,6Pyrogas

39,838,939,139,937,138,339,539,0ETHYL+PROP

12,0 12,0 12,2 14,2 10,6 10,4 15,7 14,7 Propylene

27,8 26,9 26,9 25,7 26,5 27,9 23,8 24,3 Ethylene

Yields, m/m%

0,470,490,490,490,430,480,460,46Water mass ratio

800800771769796794771769Severity

0,300,300,440,420,500,480,290,28Contact time, sec

860860810810830830830830Temperature, °C

4B 4A 3B 3A 2B 2A 1B1A

‘B’: Gas oil + LPPE (10 m/m%)

Pinter, A., Tungler, A., Nagy, l., Vida, L., Gál, T., Kerezsi J., "A Laboratory Steam-Cracking Reactor to Characterize Raw Materials," International Journal of Chemical Reactor Engineering, Vol. 2, A15. http://www.bepress.com/ijcre/vol2/A15

Summary: steam-cracking seems to be a promising solution for recycling of polyolefin wastes as the yield of monomers is good, the process can be integrated into the existing olefin production units.