DEVELOPMENT OF COMPETITIVE COMBINED REACTIVE- SEPARATION PROCESSES IN CHEMICAL ENGINEERING

Prepared by: Prof. William Zadorsky, Ukrainian State University of Chemical Engineering, Pridneprovie Cleaner Production Center

E-mail: ecofond@ecofond.dp.ua

Stanislav Induchny, Technology Transfer Consultant

E-mail: Induchny@btinternet.com

Reactive separation processes were introduced into chemical technology rather recently (approximately 30 years ago) and proved to have conclusive advantages over conventional technologies in terms of their efficiency. [1,2].

Combination of the chemical reaction with the physical process of reaction mass separation in one single integrated operation is an effective method for technological processes intensification. It has been established that the removal of reaction products in the process of their formation facilitates the increase in the rate of both reversible processes according to Le-Schatelie principle, and irreversible reactions due to the law of mass action (as the removal of reaction products results in the increase of reagents concentration in the reaction zone).

The increase in the rate of the reactive-mass-exchange process promotes a faster change in surface tension at the interface boundary of phases and in the density of phases. This results in the enhanced surface turbulence, which in its turn accelerates the mass-exchange process - the removal of reaction products from liquid phase into gas phase, thus intensifying the chemical process in liquid phase. Evidently, there are strong mutual influences of both chemical and diffusion processes [3].

Thus, it has become possible to considerably increase the rate of many chemical processes and achieve higher product yields, coupled with reduced capital and operational costs, lower energy consumption and decreased harmful emissions.

The combined reactive separation processes can be successfully implemented even on the basis of conventional chemical technologies. A number of practical applications and industrial trials carried out in the production of organic and inorganic products have demonstrated the potential of the new approach as a universal method in technology intensification. 

For example, we have applied the reactive separation process in the conventional technology for dimethylformamide synthesis. The trial results were compared to the working parameters of existing conventional installations. The trial installation demonstrated the following advantages [4]:

• The process rate was increased by a factor of 58 (trial 430 kg / m³hr compared to conventional 7,4 kg / m³hr).
• The process duration was reduced by a factor of 80 (trial 0,6 hours compared to conventional 48 hours).
• The conversion rate reached over 95 %.
• Specific costs of steam and water usage were reduced by a factor of 2.
• Electricity demand was reduced by a factor of 4.5.

Laboratory research and industrial trials have demonstrated that the reactive separation operation can be successfully implemented in a wide range of known chemical processes such as oxidation, esterification, condensation, hydration of olefins, dehydration, condensation processes, halogenation of hydrocarbons, etc.

Opportunities for the reactive separation process exist even in the countries with highly advanced chemical industry (such as USA, Japan, Germany etc.), where, as an example, the process can be applied for: condensation and polycondensation in the production of polymeric materials, isomerisation in the manufacture of half-products for semi-conductor materials, depolymerization of cyclic compounds etc.

Our specialists have developed a solid knowledge base and gained a great practical experience in the research of macro-kinetics of the reactive separation processes (catalytic synthesis in particular) and the design of optimum equipment configuration.

We are in a position to offer our expertise to interested companies/organizations in the field of:

• Development of the theoretical basis for reactive separation processes in catalytic systems and optimization of structural and operational designs;
• Research in macro-kinetics of chemical processes in three-phase systems (gas – liquid – solid substance) for the determination of equipment design parameters;
• Development of basic reactive separation processes for specific applications and their improvement in laboratory conditions;
• Development and implementation of pilot trials in industrial conditions;
• Development of a generic methodology for the design of reactive separation process equipment.

For further enquiries please contact Mr Stanislav Induchny by phone + 44 1235 810237 or via e-mail Induchny@btinternet.com

References:

1. O.Levenspiel. Chemical Reaction Engineering. John Wiley and Sons. Inc. New York - London.1965.

2. G.Astarita. Mass-transfer with Chemical Reaction. Elsevier Publishing Company. Amsterdam-London-New York. 1967

3. Patent USA 4232117, C 07 C 1/20, Catalytic distillation process/ Smith L.A. Chemical research and Licensing Company (USA) - N13559, 21.02.79

4. Zadorsky W. Intensification of Chemical Technology Processes on the Systematic Aproach Base. Kiev. «Technika». 1989. 208p.