Summary for the A7 example simulation

This example demonstrates how you can use AVEVA Process Simulation to simulate the synthesis of methyl tert-butyl ether (MTBE). It uses and highlights the following features in AVEVA Process Simulation:

• Petrochemical applications

• Local overrides for binary interaction parameters

• Stoichiometric reactor units

• Multi-tray reactive distillation columns

• Complex reaction kinetics submodels

• Liquid-liquid extractor columns that use vapor-liquid-liquid equilibrium (VLLE) thermodynamics

• Column diameter estimation by using simple tray calculations

  Note: This example is based on the AVEVA PRO/II Simulation Casebook: Methyl Tertiary Butyl Ether. Small differences between this example and the AVEVA PRO/II Simulation casebook are due to rounding during data transfer, slightly different conditions, or different choices for the column specifications.

MTBE is an octane enhancing agent for unleaded motor gasoline. It has several desirable properties that make it a suitable gasoline additive:

• It has a low boiling point and an RVP of 8–10 psi. This causes the gasoline enhanced with MTBE to have a lower vapor pressure. The lower vapor pressure results in reduced emissions.

• It has an octane number of approximately 109. When MTBE is mixed with gasoline, it increases combustion without reducing engine power.

• It increases the front-end octane number, which reduces engine knocking during acceleration.

• The addition of MTBE to gasolines generally implies a reduced aromatic and butane content, which leads to reduced carbon monoxide and hydrocarbon emissions.

Typically, MTBE is produced from the butylenes in the product streams of liquid-feed ethylene crackers and fluid catalytic crackers (FCCs). Some plants use raffinates from butadiene extraction or catalytic butane dehydrogenation to produce MTBE. MTBE synthesis also offers a method of selectively removing isobutylene from mixed C4 streams. This enables the recovery of high purity 1-butene and 2-butene, which are superior feedstocks for sulfuric acid alkylation.

There are numerous variations on MTBE plant designs. In general, an MTBE plant includes three sections: a reactor section, an MTBE recovery section, and a methanol recovery section. For the Ethermax process, the MTBE recovery section includes a second reaction zone in the distillation column. The following figure shows the complete process flow diagram for the MTBE reactive distillation plant modeled in this example simulation.

Figure 1: An MTBE plant modeled in AVEVA Process Simulation