OP-II-3

OP-II-8the reactor [6]. However, the recycling of downstream gas alters the composition ofinlet gas and the components ratios in it. This was not taken into account in [5, 6].In this work, the mathematical modeling of NA synthesis process by βP airoxidation in multi-tubular reactor was carried out, and the factors impacting theprocess efficiency were studied. Special attention was given to the role of recycle.The analysis was based on a two-dimensional quasi-homogeneous mathematicalmodel of a tubular reactor, which took into account the radial diffusivity and heatconductivity, axial convective mass and heat transfer, radial profile of porosity [7] andwas based on a kinetic model of βP oxidation over V 2 O 5 –TiO 2 ring-shaped catalysthaving sizes 4 mm OD, 2 mm ID, and 5 mmlength [1].2118It was shown that when the portion of therecycling gas increases the portions of the effluent15121,11,0870,81,11,0 0,884gas and of the fresh air decrease. This results in8178decrease of О 2 /βР ratio (Fig.3). The existing75bounds on permissible values of О 2 /βР ratio implybounds on the inlet βР concentration and on the701,01,1portion of recycle. At the optimally selected0 10 70 75 80 85Portion of recycling, %parameters of recycling, this provides for Fig.3. Influence of recycling gassubstantial increase of S NA , of the overallportion on the process parameters.Inlet concentration of βP (mol.%):conversion X and of the yield of NA.0.8, 1.0 and 1.1Optimal regimes were simulated and proposed for technological schemes with andwithout recycle. The use of recycle after NA separation allows to increase theproductivity of the catalyst volume by 13.7%, to increase the yield of NA by 6.7%, to cutthe length of tubes by 40%, to decrease the total metal capacity of the tubular section ofthe reactor by 13.5%, and to decrease the βP consumption per 1 ton of NA by 8.3%.References[1]. Ovchinnikova E.V., Andrushkevich T.V., Popova G.Ya., Meshcheryakov V.D., ChumachenkoV.A., Chem. Eng. J., V.154, P.60 (2009).[2]. Andrushkevich T.V., Balzhinimaev B.S., Kashkin V.N., Nakrokhin V.B., Ovchinnikova E.V.,Zolotarskii I.A., RU 2371247, (2009).[3]. Chesalov Yu.A., Ovchinnikova E.V., Chernobay G.B., Popova G.Ya., Andrushkevich T.V.,Catalysis Today, (2010), in Press, doi:10.1016/j.cattod.2010.01.065.[4]. Parulekar S.J., Waghmare R.S., Lim H.C., Chem. Eng. Sci., V.43, P.3077 (1988).[5]. Heinz D., Hoelderich W., Krill S., Boeck W., Hutchmacher K., CA2281293 (EP-984005), (2000).[6]. Andrushkevich T.V., Popova G.Ya., Al’kaeva E.M., Makarenko M.G., Zenkovez G.A., Chem. Ind.,№3(165), P.23 (1996) (in Russian).[7]. Kagyrmanova A.P., Zolotarskii I.A., Vernikovskaya N.V., Smirnov E.I., Kuzmin V.A., ChumakovaN.A., Theor. Found. Chem. Eng., V.40, P.155 (2006) (in Russian).O 2/βPS NA, %X βP , %90801,11,0 0,80,8113