Methanol, production adiabatic reactor

The fresh feed, which contains CO and H2 in stoichiometric proportion, enters the process at a rate of 2.2 m /s at 25°C and 6,0 MPa and combines adiabatically with a recycle stream. The combined stream is heated to 250°C and fed to the reactor. The reactor effluent emerges at the same temperature and is cooled to 0°C at P - 6.0 MPa, partially condensing the methanol product. The gas leaving the condenser is saturated with methanol 1% is taken off for process monitoring purposes and the remainder is recycled. An overall CO conversion of 98% is achieved. The ratio of H2 to CO is 2 mol H2/I mol CO everywhere in the process system. Ideal gas behavior may be assumed. 

ADIABATIC TUBULAR REACTOR/METHANOL PRODUCTION IN GAS PHASE... 

To obtain the adiabatic reaction temperature for complete conversion, the heat duty is set at zero and the pressure of the methanol product stream is returned to 1 atm. This produces an effluent temperature of 1,158°C (2,116°F), which is far too high for the Cu-based catalyst and the materials of construction in most reactor vessels. Hence, a key question in the synthesis of the methanol process, and similar processes involving highly exothermic reactions, is how to lower the product temperature. In most cases, the designer is given or sets the maximum temperature in the reactor and evaluates one of the heat-removal strategies described in this section. 

Methanol can be produced as co-product in the ammonia synthesis [239] [406]. The CO and CO2 for the methanol synthesis is obtained by a partial bypass of the shift converters and the CO2 wash. The methanol synthesis takes place in an adiabatic reactor or a simple once-through boiling water reactor and the unconverted S5mgas is passed through a methanator back to the ammonia synthesis loop. 

The following subsection briefly describes current industrial processes for methanol production with adiabatic multi-bed and isothermal single-bed reactor design. We will refer to the ICI (adiabatic multiple-bed reactor) and to the Lurgi process (isothermal single-bed reactor), which are important representatives of the different ways of producing methanol commercially nowadays. 

Other examples of methanol production processes using adiabatic multiple-bed reactor concepts are the Haldor Topsoe process and the Kellogg process. 

The final step in the methanol-to-gasoline process can be carried out in an adiabatic, fixed-bed reactor using a zeolite catalyst. A product mixture similar to ordinary gasoline is obtained. As is typical of polymerizations, a pure reactant is converted to a complex mixture of products. 

Methanol flows at the rate of 1000 kmol/h (22051b mol)into the reactor, shown in Figure 3.4.1, where methanol is oxidized catalytically to formaldehyde under non-adiabatic conditions. The reactants enter the reactor at 500 °C (932 °F), and the products exit at 600 °C (1110 °F). The methanol in stream 1 and air in stream 2 are both at 500 °C, and the methanol conversion is 80 %. To minimize possible combustion of methanol and formaldehyde, we set the molar flow rate of oxygen at 80% of the stoichiometric quantity. The reaction is... 

Some of the many processes using adiabatic fixed-bed reactors with gaseous reactants are the production of methanol and ammonia, and hydrotreating of naphtha. 

Partial oxidation provides quick start-up and compactness, while steam reforming produces relatively high concentration of hydrogen in the product gas. The steam reforming is endothermic and the partial oxidation is exothermic so that the combination of these two reactions in appropriate proportion allows close to thermal neutrality, or adiabatic conditions at the desired temperature. HotSpot reactor systems have been developed for the autothermal reforming of methanol. ... 

The search continues for better and more economical processes for the production of ethylene. Those processes include catalytic thermal cracking, methanol to ethylene, oxidative coupling of methane, advanced cracking technology, adiabatic cracking reactor, fluidized bed cracking, membrane reactor, oxydehy-drogenation, ethanol to ethylene, propylene disproportionation, and coal to ethylene. Much work is still needed before any such process can compete with current processes. 

In the following sections, we will analyse the dynamic behaviour of a gas-fed, adiabatic, catalytic-bed reactor, of the sort commonly used for methanol and ammonia production. Figure 20.4 gives a schematic representation of an element from such a... 

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