engineering. tomorrow. together.
Process description
The standard methanol plant concept consists of the following process steps:
feed purification, steam reforming, syngas compression, methanol synthesis and crude methanol distillation.

The feedstock (natural gas, for example) is desulphurised, mixed with steam and converted to synthesis gas in the reformer over nickel catalysts at 20 bar to 35 bar pressure and at temperatures of 800 °C to 950 °C. The Uhde steam reformer is a top-fired reformer with tubes made of centrifugally-cast high alloy steel and a proprietary "cold outlet manifold system" to enhance reliability.

The reformed gas at the reformer outlet is a mixture of hydrogen, carbon oxides and residual methane. It is cooled from approximately 880 °C to ambient temperature. Most of the heat from the synthesis gas is recovered by steam generation, BFW preheating, heating of the crude methanol distillation section and by demineralised water preheating.

Also, heat from the flue gas is recovered by feed/feed-steam preheating, steam generation and superheating as well as combustion air preheating. After final cooling, the synthesis gas is compressed to synthesis pressure, which ranges from 40-110 bar (depending on plant capacity) before entering the synthesis loop. The synthesis loop consists of a recycle compressor, feed/effluent exchanger, methanol reactor, final cooler and crude methanol separator.

Crude methanol, which is condensed downstream of the methanol reactor, is separated from unreacted gas in the separator and routed via an expansion drum to the crude methanol distillation. Water and minor quantities of by-products formed in the synthesis and contained in the crude methanol are removed by a distillation system.
 
 
top  Printer friendly version