INTRODUCTION:

Electromagnetic aspects of energy transfer between microwaves and other forms of matter are comprehended in processes where Microwave energy is used to affect a chemical or physical change. Though its implications in petroleum applications are yet to be fully Understood, the non-thermal aspects of energy transfer between Microwaves and other forms of matter are always visible in processes Where microwave energy is used to cause a chemical or physical Change in the irradiated material. The depletion of conventional Crude oil reserves is accompanied by growing economic demand for various types of fuel, biodiesels and petrochemical products creating the need for remediation of heavier as phaltenic crude.¹ Thus, the Extraction, transportation and refining of this highly viscous, high Paraffinic, high sulphur content crude oil and its wastes is becoming More prominent since heavy oil deposits exceed light oil deposits by Two orders of magnitude.²

In this work, multiple crude oils were Studied for hydro-desulphurization (HDS) and defragmentation Processes by a novel method of microwave irradiation. The specific Objectives were to identify conditions that would upgrade the oil and simultaneously substantially reduced the sulphur content using Microwave irradiation, and to obtain preliminary data on process Economics. Results showed strong indications for the microwave Technology to be employed not only for hydrocarbon extractions but also for in-situ and field upgrading of heavy oil, and reduction in Sulphur content of crude oil. There was evidence of fragmentation and Combination reactions present in the process, as well as high percent Reduction in sulphur content. Overall, the microwave technology presents the best alternative, economically and environmentally, To the existing technologies for enhanced oil recovery operations and Processing. The microwave process employs specific frequency microwaves Targeted into the formation containing heavy hydrocarbons to initiate Conversion of the hydrocarbon into synthetic crude, with reduced Discharge of greenhouse gas into the environment as natural gas Or other fuels are not required to reduce viscosity.³The specific Objectives were to identify conditions that would upgrade the oil and Achieve up to 50% desulphurization using microwave irradiation, and To obtain preliminary data on process design and economics.¹

Statement of the Problem:

Microwave energy is gradually becoming the most diverse form of energy transfer. It has been used with great success in the petroleum industry for inspecting coiled tubing and line pipe, measuring multiphase flow and the mobilization of asphaltic crude oil. Though its implications in petroleum applications are yet to be fully understood, the electromagnetic aspects of energy transfer between microwaves and other forms of matter are well comprehended in processes where microwave energy is used to effect a chemical or physical change. The depletion of conventional crude oil reserves is accompanied by growing economic demand for various types of fuel, giving more prominence to heavy oil and bitumen which deposits exceed light oil deposits by two orders of magnitude. In Canada, efforts have been intensified to develop microwave irradiation technology for in situ enhanced oil recovery of the country’s large deposits of bitumen and heavy oil. Of the estimated 30 billion barrels of heavy oil in place, about 26 billion barrels are considered unrecoverable using the current technology. The specific objectives were to study microwave process conditions that would affect the upgrading of heavy oil/bitumen to synthetic crude and achieve up to 50% desulphurization as well As obtain preliminary data on process design and economics.^1,2,3

Methodology and Theoretical Orientation:

In a typical experiment, oil was mixed with one or more of additives and exposed to Various dosages of microwave radiation at low pressure. The microwave reactor was constructed from a domestic microwave oven which was modified to allow for the accommodation of a mixer, a device to monitor temperature and pressure in the reactor and interfaced with a desktop computer for data acquisition. The power level and irradiation intensity was at level high.

Findings:

Results obtained with GC-MS showed evidence of fragmentation process in heavy oil/bitumen samples but, no significant change in molecular structure for majority of the light crude oil samples after being subjected to microwave irradiation. Average reduction in sulphur content of 16% and 39.4% were obtained for heavy oil and light oil respectively. Reduction in sulphur content of 16% and 39.4% were obtained for heavy oil and light oil respectively⁴. Conclusion and Significance: The work done so far showed strong indications for the microwave technology to be employed not only for hydrocarbon extractions but also for in situ upgrading and field upgrading of heavy oil and bitumen desulphurization of crude oil and future upgrading of coal and oil shale. Overall, the microwave technology presents the best alternative, economically and environmentally, to the existing technologies for enhanced oil recovery operations and processi.⁵

Conclusion and Significance:

The work done so far showed strong indications for the microwave technology to be employed not only for hydrocarbon extractions but also for in situ upgrading and field upgrading of heavy oil and bitumen desulphurization of crude oil and future upgrading of coal and oil shale⁶. Overall, the microwave technology presents the best alternative, economically and environmentally, to the existing technologies for enhanced oil recovery operations and processing.^7,8

Figure 1: Typical process mechanism for the microwave irradiation of crude oils.

Advantages of microwave high-temperature processing

Reduced energy consumption and process time

The main advantages of microwave heating stem from direct energy deposition in the volume of a material. This eliminates the need for spending energy on heating the walls of the furnace or reactor, its massive components, and heat carriers. As a result, the use of microwave methods significantly reduces energy consumption, especially in high-temperature processes, since heat losses grow dramatically with an increase in the process temperature^9,10. The volumetric nature of energy deposition accelerates heating, which reduces the time needed to complete a process. An idea of the energy saving potential of microwave processing can be inferred from the results of a number of comparative studies in sintering. According to one of them the specific energy consumption in the process of sintering alumina-based ceramics at a temperature of 1600^◦C is about 4 kWh kg−1 for microwave heating versus 59 kWh kg−1 for fast conventional heating in a resistive oven. For the sintering of silicon nitride-based ceramics, the specific energy consumption is 3 kWh kg−1 over a 2 h process of microwave sintering versus 20 kWh kg−1 over a 12 h conventional process. The reduction in process time under microwave heating is especially significant when the process involves endothermic chemical reactions and/or phase transformations and the temperature is limited from above (either by the capabilities of the system or by product quality). In this case a sufficient energy supply is a prerequisite for a high process rate, which is determined at each point by the local temperature. Conventionally, the energy supply rate is always limited by slow heat transfer processesn.^{11, 12} Due to volumetric energy deposition, microwave heating is, in principle, capable of providing any desired rate of an endothermic process, limited only by the power of the microwave source. However, it should be emphasized that the advantages of using microwave energy in high-temperature processes are by no means reduced only to energy saving.^13,14

Non-thermal microwave effects:

Experimental identification of non-thermal effects As long as microwave processes of high-temperature treatment differ from the processes that do not use microwaves, one of the questions arising is: is the difference due only to a different heat deposition pattern, or do microwave electromagnetic fields play a role in it? The problem of the so-called ‘microwave effects’ has become one of the most controversial issues in the recent literature on the microwave processing of materials.^15,16 While some of the researchers tend to use the term ‘microwave effect’ to denote any and all distinctions of the microwave- assisted processes from those not using microwaves, others propose to limit its meaning to only those observations which cannot be explained in full on the basis of current knowledge in the field. This section reviews the physical aspects of the effect of microwave electromagnetic fields on mass transport in solids. In principle, the term ‘microwave effect’, or, more strictly, ‘microwave field non-thermal effect’ should be reserved for the deviations of microwave processes from conventional processes that occur given identical temperature dynamics, T (r,t), of these processes. In practice, at least two general problems challenge the identification of non-thermal effects. One of them is inaccurate or incomplete temperature measurements. Thermocouple sensors generally measure the temperature of the thermocouple head, which may be close to the temperature of the material at the point which the head touches, but it can still differ substantially from the temperature in most other points of the material.^17,18,19The reasons are heat losses via the thermocouple, microwave absorption in the thermocouple, etc. Pyrometers measure temperatures on the surface of the material but these are different from those in the bulk. Millimetre-wave tomography methods that can provide information on the temperature inside the material are hardly applicable to high-temperature processing conditions. In general, it is not feasible to obtain accurate data on the dynamics of temperature at all points. The second problem is that it is impossible to devise a pair of a microwave and conventional processes that would have identical temperature fields. In particular, as discussed above, it is not possible to implement a microwave heating process with a uniform temperature distribution in the material undergoing processing. Temperature gradients are a fundamental attribute of microwave volumetric heating, and the effects caused by them indeed contribute to differences in the process flow. Possible mechanisms of the influence of temperature gradients are, for example, thermoplastic stresses, and thermal diffusion. However, both experimental and theoretical studies suggest that temperature gradients are generally not the main reason for enhanced mass transport rates. There are many experimental observations that suggest non-thermal influence of microwave fields on mass transport. One of the phenomena first observed and still not yet explained in full was the enhancement of oxygen diffusion in sapphire crystals heated in a 28 GHz millimetre-wave furnace. A 40% decrease in the apparent activation energy for bulk diffusion was observed under millimetre-wave heating as compared to conventional heating.^20,21,22

Basic physical concepts of microwave high-temperature processing:

Microwave absorption Microwave heating is based upon the capacity of a material to absorb the electromagnetic energy. It is known that in dielectric materials the external electric field causes a redistribution of internal bound charges, which results in the polarization of the material. A measure of such a response of a material to an external electric field is the dielectric permittivity, ε1. If the external electric field is alternating (ac), the dielectric response of the material follows it, generally with some lag behind the field changes. To describe this phenomenon quantitatively a complex dielectric permittivity that depends on the field frequency, ω, is formally introduced: ε (ω) = ε-(ω) + iε--(ω). The imaginary part of the dielectric permittivity is greater the larger the lag. The change of polarization, i.e. the redistribution of internal charges, is accompanied by the motion of electric charge, i.e by the electric ac current, which generates heat inside the material.^[13][24] The effective high-frequency conductivity, σ, can be introduced in order to characterize the power of heating, similar to the case of a dc current. The power of heating per unit volume, which equals the absorbed microwave power, is w = σ E2 (2.1) where E is electric field strength inside the material. The effective high-frequency conductivity is unambiguously linked to the imaginary part of the dielectric permittivity, σ = ωε0ε-- where ε0 is a constant called the permittivity of free space. Because of absorption, the electromagnetic fields decrease as the wave passes through the material. The dissipation of electromagnetic energy is commonly characterized by the so-called loss factor, tan δ = ε--/ε-. The attenuation of the electromagnetic wave can also be characterized by a penetration depth (or skin depth), on which the field strength is reduced by a factor of e = 2.71 ...: l = cω2 [1 + -1 + (tan δ) 2] ε-(tan δ) 2, (2.2) where c is the velocity of light.^25,27When the electromagnetic wave is incident (from air or vacuum) onto a plane surface of material, it is partly reflected from the surface and partly penetrates into the material. 1 In most dielectric materials the magnetic component of the electromagnetic field does not contribute to microwave absorption, and will not be considered here. However, magnetic effects are important in the interaction of microwaves with metals and can be determining in the microwave absorption of metal– dielectric composites.²⁷

Microwave application to tire recycling and oil shale etc.

Used tires and what to do with them is a huge worldwide problem. They do not disintegrate like an organic material and do not perish for at least 200 years. They have a tendency to combust spontaneously in stockpile and therefore pose a significant environmental and safety hazard. Over a billion used tires are discarded in the dump sites per year worldwide to be reused/recycled. The major components of the tires are steel, hydro-carbons and carbon black. All these components are very desirable commercially if can be recovered econom-ically and effectively into useful products sutgch as oil and diesel. The conventional heating and recycling processes are neither economical nor efficient in producing commercial grades products. Efforts to recycle the used tires have been attempted by many researchers in the past.17–19 Most attempts were based on single frequency (2?45 GHz) microwave technology. However, the recent attempt by Glenn Research Center19 using a variable frequency microwave recovery process seems to have potential of economical, efficient and effective method for recycling used tires.^[28] Almost 100% content of the tire is shown to have converted into useful products such as steel, oil, solid carbon and heating gas. Oil shale refers to any sedimentary rock that contains solid bituminous materials that are released as petroleum-like liquids. When this rock is heated in a special process (retorting) the petroleum products are released. There are vast deposits of these rocks in US, Canada and other countries.^29,30,31 The continued soaring prices of the petroleum are forcing the researchers to find a suitable way to tap the large reserves of oil buried in the shale. However, the conventional processes to recover petroleum from oil shale are neither economical nor efficient. It is well recognised that if an energy efficient and effective technology is developed to extract oil from oil shale that will solve the global energy and oil problem for many centuries to come. Global resource Corp. in a US patent application19 has shown that variable micro-wave frequency based technology can be applied to heat oil shale to produce gases which can be condensed into petroleum products with high Caloforic Value.^32,33,34

CONCLUSIONS:

Microwave irradiation presents a potential alternative to the Highly costly desulphurization process presently used in the industries Promoting simultaneous fragmentation and recombination of Molecules. When used in combination with the appropriate catalyst, Sensitizer and other process parameters, microwave irradiation can Be used for desulphurization and upgrading of heavy sour crude oil; The sensitizers and additives promote simultaneous fragmentation and recombination of molecules. Up to 39% desulphurization of the Original heavy crude oil, mainly at the light fractions can be obtained with an increased expectancy through further investigation. Regarding Future work there is a need for further trial regarding optimization of microwave time as well as identification of a possible retention Time which may present the greatest issue as numerous samples were Indicative of such changes; if this problem endures, investigation Must be taken to ensure this is mitigated for the purposes of future Industrial application.

REFERENCES:

1. Britten AJ, Whiffen V, A Miadonye A (2005) “Heavy Petroleum Upgrading by Microwave Irradiation”, WIT Transactions on Modelling and Simulation41: 103-112.

2. MiadonyeMiadonye A, J Cyr, K Secka, A Britten “Study of the Thermo-physical Properties of Bitumen in Hydrocarbon Condensates.” Computational Methods and Experimental Measurements XIV: 125-134.

3. Miadonye A, MacDonald B (2014) tty Radiation Induced Visbreaking Of Heavy Crude Oil. Journal of Petroleum Science Research 3: 130.

4. MiadonyeMiadonye A, Snow S, Irwin DJG, RM Khan, A Britten, et al. (2009) “Desulfurization of Heavy Crude Oil by Microwave Irradiation”, Publ, WIT Transactions on Engineering Sciences 63: 455-465.

5. K-TEK specializes in manufacturing a broad range of high reliability levelInstruments. (2016). Asiinstr.com. Retrieved 19 May 2016, from http://asiinstr.Com/technical/Dielectric constants.htm

6. Shang H, Guo Y, Yang X, Zhang W (2011) Influence of materials dielectric Properties on the petroleum oil removal from waste under microwave Irradiation. The Canadian Journal of Chemical Engineering 90: 1465-1471.

7. Varadan V K et al 1988 Microwave Processing of Materials (Materials Research Society Symp. Proc. Vol 124) Ed W H Sutton et al (Pittsburgh, PA: Materials ResearchSociety) pp 45–7

8. Kriegsmann G A 1992 J. Appl. Phys. 71 1960–6

9. Janney M A and Kimrey H D 1990 Microwave Processing of Materials II (Materials Research Society Symp. Proc.Vol 189) ed W B Snyder et al (Pittsburgh, PA: MaterialsResearch Society) pp 215–27

10. Bykov Yu V et al 1990 Microwave Processing of Materials II (Materials Research Society Symp. Proc. Vol 189) Ed W B Snyder et al (Pittsburgh, PA: Materials Research Society) pp 41–2

11. Link G et al 1996 Microwave Processing of Materials V (Materials Research Society Symp. Proc. Vol 430) Ed M F Iskander et al (Pittsburgh, PA: Materials Research Society) pp 157–62

12. Eastman J A et al 1990 Microwave Processing of Materials II (Materials Research Society Symp. Proc. Vol 189) Ed W B Snyder et al (Pittsburgh, PA: Materials Research Society) pp 273–8

13. Ho W W 1988 Microwave Processing of Materials (Materials Research Society Symp. Proc. Vol 124) ed W H Sutton et al (Pittsburgh, PA: Materials Research Society) pp 137–48

14. Birman A et al 1995 Microwaves: Theory and Application in Material Processing III (Ceramic Transactions vol 59) Ed D Clark et al (Westerville, OH: The American Ceramic Society) pp 305–12

15. Gerdes T et al 1996 Microwave Processing of Materials V (Materials Research Society Symp. Proc. Vol 430) Ed M F Iskander et al (Pittsburgh, PA: Materials Research Society) pp 45–50

16. Carr G L et al 1985 Infrared and Millimeter Waves vol 13,Ed K J Button (New York: Academic) pp 171–63

17. Bergman D J and Stroud D 1992 Solid State Physics: Advances in Research and Applications vol 46,Ed H Ehrenreich and D Turnbull (New York: Academic) Pp 147–269

18. Sahni, M. Kumar, R. Knapp, Electromagnetic heating methods for heavy oil re Servoirs, Society of Petroleum Engineers, SPE-62550 presented at the SPE/AAPG Western Regional Meeting held in Long Beach, California, June 19–23, 2000.

19. Strausz, E.M. Lown, The Chemistry of Alberta Oil Sands, Bitumen and Heavy Oils, AERI, Calgary, AB, 2003, pp. 29–35.

20. G. Gallone, G. Levita, A. Marchetti, S.C.M. Fantozzi, M. Lucchesi, Broad band di- Electric analysis of bituminous concrete, Materials Research Innovations 8 (1) (2004) 36–40.

21. F.S. Chute, F.E. Vermeulen, Present and potential applications of electromagnetic Heating in the in-situ recovery of oil, AOSTRA Journal of Research 4 (1) (1987) 19–33.

22. G.C. Sresty, H. Dev, R.H. Snow, J.E. Bridges, Recovery of bitumen from tar sand Deposits with the radio frequency process, SPE Reservoir Engineering, January 1986, pp. 85–94.

23. R.G. McPherson, F.S. Chute, F.E. Vermeulen, Recovery of Athabasca bitumen with the electromagnetic flood (EMF) Process, Journal of Canadian Petroleum Technol- Ogy (January–February 1985) 44–51.

24. R.S. Kasevich, M. Kolker and A.S Dwyer, In-situ radio frequency selective heating Process and system, US Patent 4,301,865, Nov.24, 1981.

25. Defence News, Raytheon technology shows promise in extracting oil from shale, Microwave Journal 49 (7) (2006) 39.

26. L.L. Schramm, Emulsions fundamentals and applications in petroleum industry, Wiley-VCH, Washington DC, 2006.

27. N.O. Wolf, Use of microwave radiation in separating emulsion and dispersions of Hydrocarbons and water U.S. patent 4,582,629, April 15, 1986

28. C.S. Fang, P.M.C. Lai, B.K.L. Chang, W.J. Klaila, Microwave demulsification, J. Environ. Prog. 8 (1989) 235–238.

29. P.J. Nilsen, A. Kornfeldt, T. Nygren and R.B. Fdhila, Method for separating an emul-Sion by using microwave radiation, Patent WO 0112289, 2001.

30. X.Zhang, D.O. Hayward, Applications of microwave dielectric heating in environ- Ment-related heterogeneous gas-phase catalytic systems, Inorganic Chimica Act 359 (2006) 3421–3433.

31. X. Zhang, D.O. Hayard, D.M.P. Mingos, Dielectric properties of MoS2 and Ptcata- Lysts: effects of temperature and microwave frequency, Catalysis Letters 84 (2002) 225–233.

32. Z. Zhang, H. Chauhan, R. M. Hutcheon, The Microwave response of mixtures of Polar and non-polar liquids, relevant to the microwave-assisted catalytic hydro-Processing of Canadian bitumen fractions, (unpublished results from University of Ottawa).

33. J.K.S. Wan, J. F. Kriz, Hydrodesulphurization of hydro cracked pitch, US patent 4545879 October 8, 1985.

34. J.K.S. Wan, K. Wolf, R.D. Heyding, in: S. Kaliaguine, A. Mahay (Eds.), Catalysis on The Energy Scene, Elsevier Science Ltd, 1984, pp. 561–568.

35. M.C. Depew, M.Y. Tse, H. Husby, J.K.S. Wan, High power pulsed microwave catalytic Processes: a new approach to hydrocarbon oxidation and sulfur reduction, 11^th Canadian Symposium on Catalysis (1990) 168–177.

Received on 16.10.2021 Modified on 20.12.2021

Asian J. Res. Pharm. Sci. 2022; 12(2):128-132.

DOI: 10.52711/2231-5659.2022.00021