A process for methanol synthesis is shown in Figure P12 25 The pertinent chemical reactions are 10 excess steam, based on reaction (a), is fed to the reformer, and conversion of methane is 100 , with a 90 yield of CO 2 Conversion in the methanol reactor is 55 on one pass through the reactor A stoichiometric quantity of oxygen is fed to the CO converter, and the CO is completely converted to CO 2 Additional makeup CO 2 is then introduced to establish a 3 to 1 of H 2 to CO 2 in the feed stream to the methanol reactor The methanol reactor effluent is cooled to condense all the methanol and water, with the non condensible gases recycled to the methanol reactor feed The H 2 CO 2 ratio in the recycle stream is also 3 to 1 Because the methane feed contains 1 nitrogen as an impurity, a portion of the recycle stream must be purged as shown in Fig P12 25 to prevent the accumulation of nitrogen in the system The purge stream analyzes 5 nitrogen On the basis of 100 mol of methane feed (including the N 2 ), calculate a) How many moles of H 2 are lost in the purge b) How many moles of makeup CO 2 are required c) The recycle to purge ratio in mol mol d) How much methanol solution (in kg) of what strengh (weight percent) is produced CH4 2H2OCO2 4H2CH4 H2OCO 3H22CO O22CO2CO2 3H2CH3OH H2O(mainreformerreaction)(reformersidereaction)(COconverterreaction)(methanolsynthesisreaction) (b) (d)

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A process for methanol synthesis is shown in Figure P12.25. The pertinent chemical reactions are: 10% excess steam, based on reaction (a), is fed to

A process for methanol synthesis is shown in Figure P12.25. The pertinent chemical reactions are:

10% excess steam, based on reaction (a), is fed to the reformer, and conversion of methane is 100%, with a 90% yield of CO₂. Conversion in the methanol reactor is 55% on one pass through the reactor.

A stoichiometric quantity of oxygen is fed to the CO converter, and the CO is completely converted to CO₂. Additional makeup CO₂ is then introduced to establish a 3 to 1 of H₂ to CO₂ in the feed stream to the methanol reactor.

The methanol reactor effluent is cooled to condense all the methanol and water, with the non-condensible gases recycled to the methanol reactor feed. The H₂/CO₂ ratio in the recycle stream is also 3 to 1.

Because the methane feed contains 1% nitrogen as an impurity, a portion of the recycle stream must be purged as shown in Fig. P12.25 to prevent the accumulation of nitrogen in the system. The purge stream analyzes 5% nitrogen.

On the basis of 100 mol of methane feed (including the N₂), calculate:

a) How many moles of H₂ are lost in the purge? b) How many moles of makeup CO₂ are required? c) The recycle to purge ratio in mol/mol d) How much methanol solution (in kg) of what strengh (weight percent) is produced.

CH4+2H2OCO2+4H2CH4+H2OCO+3H22CO+O22CO2CO2+3H2CH3OH+H2O(mainreformerreaction)(reformersidereaction)(COconverterreaction)(methanolsynthesisreaction) (b) (d)