(709e) New Catalytic Distillation Process for the Production of the Fuel Ether TAME Using Different Pressure Thermally Coupled Technology

New
catalytic distillation process for the production of the fuel ether TAME using
different pressure thermally coupled technology

Hong Li^{a, *},
Xin Gao^a, Xingang Li^{a, b}

^a
School of
Chemical Engineering and
Technology,
Tianjin University, Tianjin
300072,
China

^b
National
Engineering Research Center for Distillation Technology, Tianjin 300072,
China

Abstract

The integration
of reaction and separation in one single process unit shows several advantages
compared to the separately performed processes. Process intensification and
energy integration represent ways of economical efficiency, as well as
environmental friendly operating conditions. In this paper, the process of
catalytic distillation for tert-amyl
methyl ether (TAME) synthesis from isoamylenes (2M1B and 2M2B)
and methanol has been studied. A brief description of equilibrium stage model
developed is given for simulation of the catalytic distillation process of the
synthesis of tert-amyl methyl ether
(TAME) from isoamylenes (2M1B
and 2M2B) and
methanol. The model predicted the reaction conversion and the energy
consumption of process. Validation based on pilot plant experiments proved that
the model accuracy is satisfactory. A new process technology was designed by
means of different pressure thermally coupled technology for energy-saving.

The conventional
RD column for producing TAME consist of rectifying section, reactive section
and stripping section. The column is operated at an overpressure of 0.4MPa°«0.5 Mpa. Increasing column pressure causes increased
reaction rates and a shift of chemical equilibrium duo to higher boiling point
temperatures in the reactive distillation section. On the other hand,
increasing column pressure reduces the realative volatility. In odrer to
providing a good recovery of 2M2B
and improving the TAME purity in bottom product, the stripping section have to
increasing the energy consumption of reboiler in catalytic distillation column
bottom. So increasing the pressure of the stripping section is unnecessary.

Based on the
analysis above, different pressure thermally coupled technology could be applied
to the catalytic distillation process for producing TAME. In this process
technology, the RD column is divided to two columns with different pressure. This
unit is a highly integrated configuration as it contains a reactive part placed
in higher pressure column, products separation in the lower pressure column. The
process scheme used in our design study is shown in Fig.1. The flow scheme
consists of a pre-reactor followed by a higher pressure RD column and a lower
pressure stripping column. The top stream from the higher pressure RD column is
used as the teat energy for the reboiling of the lower pressure stripping
column, therefore the thermally coupled process is realized.

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Fig.1 The scheme of catalytic distillation
process applied to different pressure thermally coupled technology for prducing
TAME

A comparsion of
conventional catalytic distillation process for producing TAME and new
catalytic distillation process applied to different pressure thermally coupled
technology for prducing TAME shows that the energy consumption of new process
could be reduced about 46.7%. The purity of TAME obtained as bottom product of
lower pressure stripping column is high, and the excess of methanol can be
recirculated to the pre-reactor allowing a good overall yield of the process. Finally,
the equilibrium stage model is used to optimal effect parameters and design
factors of the new process technology on conversion and energy consumption. The
catalytic distillation process integrated by different pressure thermally
coupled technology seems to be a very attractive and challenging process.

Keywords: cataytic distillation, TAME, different
pressure thermally coupled, process intensification