Exhaust Processing System (Piped-Lined Type)

Exhaust Processing System (Piped-Lined Type)

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description :

The silver-catalysed formaldehyde process The silver-catalysed process produces formaldehyde by reaction of methanol vapour and air on a silver catalyst. Oxidation and dehydrogenation of methanol are the basic mechanism of the silver-catalysed route. Methanol is vaporised in an evaporator and the vapours mixed with air will go through the reactor containing a bed of pure silver in a granular crystalline form. The reactor is supported above a steam boiler so that the reaction products pass through the boiler tubes before passing to further cooling stages and produce steam (heating transfer between the reacted gases and water). The reacted gases containing formaldehyde, methanol and water are condensed and cooled in passing to a circulating absorber column followed by a first methanol scrubbing system and in a second step a water scrubbing system for the effluent gases. The aqueous formaldehyde-methanol is removed from the absorber to a distillation column to separate methanol and aqueous formaldehyde. The methanol is returned to the process as reaction feed and the aqueous formaldehyde up to 55 % formaldehyde with 1 % or less of methanol is stored into tanks. The process vent gas (after scrubbing) which contains approximately 20 % hydrogen and small amounts of methanol, formaldehyde, and methyl formiate are burned in a boiler to produce steam. We developed a 10~80kt/a formaldehyde equipment is characterized by its advanced technological process (recycled exhaust), advanced automation (DCS control system), high safety and reliable, low consumption in raw material and energy, reasonable structure (new structural oxidizing equipment) long performance life, high efficiency and other options. All the technical indexes have reached the advanced levels at home and abroad. Specifications: 1) Concentration of formaldehyde: 37~50% 2) Content of formaldehyde: ≤ 0.8% 3) Content of formic acid: ≤ 0.005% 4) Raw material consumption: ≤ 0.445T/T 5) Energy consumption: ≤ 25kWh/T