Development of new industrial shell-and-tube heat exchangers

V.M.Gureev, R.R.Yunusov, L.B.Nizamiev, G.M.Galiakberov, S.E.Tanryverdi

EET of A.N.Tupolev KSTU, JSC

Shell-and-tube heat exchanger has been developed. Its shell has a form of a truncated cone and tubes are inclined relative to the vertical central tube. Preliminary estimation has proven it to be metal-saving in comparison with the classical apparatus with cylindrical shell and tubes, with economy up to 12-15%. When such an apparatus is used as a chemical reactor, the increase of product output reaches 20%, the developments are of interest for aviation and aerospace systems. Two versions were patented by the Patent of the Russian Federation No.2372572 from 26 November 2007.

Heat exchangers are widely used in industry, particularly in petrochemistry and oil processing, performing among others energy- and resource-saving functions. The reactors themselves being basic devices can also be considered as heat exchangers, and their performance is connected with mass exchange, chemical and other processes. It concerns especially the apparatuses in which one of the heat-transfer agents penetrates through the highly porous cellular or bulk materials. Heat transfer and drag in channels is calculated allowing for the condition of maximum final efficiency of the apparatus.

Known statement is of crucial importance for selection of an optimal shape of highly porous catalysts in case of fixed catalyst layer: "Application of inserts made of cellular materials with an ideal wall contact enables to augment heat transfer 20-30 times as compared with a hollow smooth channel".

Interceptors of different shapes placed between the tubes, turbulizing inserts, ribs on outer walls of tubes, and other structures are known to be classical elements for heat transfer augmentation. They restrict flow rate and velocities of heat-transfer agents and promote flow drag. Moreover, application of additional components contributes to mass and cost increase.

Obviously, achievement of optimal efficiency is a complex problem. Development of a heat exchanger with heat transfer augmentation is the main condition for new efficient chemical-engineering system design. Ideally, catalyst functions should be combined with heat transfer augmentation using a high-porous cellular or bulk material.

The work aims at development of a high-performance heat exchanger functioning as a reactor for rigid heterogeneous catalytic processes. The corresponding schematic of reactors for heterogeneous and catalytic processes with a fixed catalyst layer was accepted to reduce expenditures in materials and power and provide small sizes of the apparatus.

New heat exchangers: design features and prospects. Shell-and-tube reactors with cone-shaped shells presented here are the apparatuses of new generation, that are an apparatus with a cone-shaped shell and inclined tubes.

In classical apparatuses with cylindrical tubes (e.g. for isoprene production by catalytic dehydrogenation of isopentane and isoamylene у₅о₁₂→у₅о₈+2о₂) during the motion of the reaction mass along the tubes, the chemical reaction shifts towards the inverse reaction. This results in decrease of reaction products outcome. For the reactor with cone-shaped tubes the outcome decrease can be avoided (the outcome can even be increased) due to proper selection of techniques for reaction mixture supply which demands additional research and tests.

Despite high heat transfer rate, shell-and-tube apparatuses have a drawback: multiple tubes lead to non-uniform supply of reaction mass to the tubes.

Tubes with downward expansion are more convenient for loading of bulk catalyst material. In this case, tube occlusion leading to incomplete loading is less likely to happen. Moreover, such occlusions resulting in gradual destruction of cylindrical tubes are less probable during the operation.

It is possible to maintain constant temperature gradient between the reaction mass and heat-transfer agent and along the tubes in the apparatuses with expanding tubes. It is critical for final catalyst preparation directly in reactor, especially when the final preparation is accompanied by generation and subsequent interaction of nanoparticles with catalyst components, the former being extremely sensitive to variation of conditions.

The developed heat exchangers have reduced mass and sizes, they demonstrate quite high heat transfer rate and could be implemented in aviation and aerospace systems. It is supposed to specify technical and economic parameters, to define the new reactor contribution to increase of efficiency of some chemical and engineering processes owing to material and power saving.

Victor Mikhaylovich Gureev, graduated from Kazan Aviation Institute (speciality - aerodynamics and thermodynamics); Leading Researcher. Field of research interests: energy saving and alternative energy sources, industrial safety of hazardous production facilities for power equipment; application areas: development of systems for utilization of gases exhausting from power and processing units with various types of heat exchangers, high-performance heat exchangers with heat transfer enhancement, heat pump units, small power plants based on gas turbines and gas engines.

Rinat Rashitovich Yunusov, student of A.N.Tupolev Kazan State Technical University; laboratory Assistant. Field of scientific interests: small-scale power engineering, audit in power engineering. Areas of application: development of new power plants.

Lut Burganovich Nizamiev, graduated from S.M.Kirov Kazan Institute of Chemistry and Technology; Researcher. Field of research interests: heat transfer augmentation in heat exchangers - reactors, complicated by chemical reactions and other processes; preservation of nano-sized particles on the tube walls and active catalyst particles in reaction conditions. Fields of application: development of new heat exchangers and catalysts for the processes of hydrogenation, dehydrogenation and partial oxidation.

Rashit Mukhtarovich Galiakberov, graduated from Kazan Aviation Institute with a degree in automatic control systems, Senior Researcher. Field of research interests: electron diffraction and electrochemistry of corrosion processes and methods for surface passivation and activation.

Sarkan E. Tanryverdi, graduated from Sakariya University (Turkey) with a degree in concrete structures; Leading Engineer. Research interests: strength of reinforced structures and assemblies, with development of power and chemical engineering equipment.