Reformeur de méthanol CH3OH. Gaz de protection pour le traitement thermique de l'acier.
Methanol (CH3OH) is a clean and efficient fuel. Like cracking ammonia, the process of methanol reforming produces no pollution. Production costs are moderate and investment is low. Methanol can be produced from renewable sources like bio gas and therefore is a green fuel. Like ammonia, methanol (CH3OH) is well suited as hydrogen carrier. Since methanol is liquid at ambient temperature, it can be transported in tanks easily. This is a big advantage compared to hydrogen gas, which has to be cooled down and stored at high pressures for transportation in huge quantities.
In a methanol reformer also called methanol cracker, a methanol mixture with demineralized water (D.M. Water) is vaporized at about 280° C using a Superheater. The gas mixture of methanol (CH3OH) and water (H2O) reacts to carbon dioxide (CO2) and hydrogen (H2) using a copper based catalyst. This so called syngas (synthetic gas) is cooled down while the methanol water mixture is heated, using a heat exchanger. During the reaction carbon dioxide and hydrogen are formed. The reaction scheme of methanol and water can be seen below:
CH3OH → CO + 2 H2
H2O + CO → CO2 + H2
CH3OH + H2O → CO2 + 3 H2
As a side product of this reaction a low amount of about 0,5% of CO is generated during this process. After this process, remaining water is removed in a condenser. In order to reduce the dew point of the generated synthetic gas further, an adsorber is used.
Two adsorber units are working in parallel. While one system is removing inpurities and un-cracked methanol from the gas mixture, the other one is heated for regeneration. Gas flow is switched regularly and automatically.
The generated hydrogen gas can optionally be further purified to up to 99,99% using a PSA (Pressure Swing Adsorption) based purifier. In this case a methanol gas reformer is well suited for fuel cell applications.
Beside hydrogen generation, the formed exothermic syngas (CO2 (carbon dioxide ) and H2 (hydrogen)) can be used for steel treatment. It can be used instead of an exogas generators which works with methane as fuel. Hydrogen is a reducing agents and avoid oxidation or corrosion of metal surfaces in a furnace. Carbon dioxide reduces the carbon contend of steel. Exothermic gas is therefore used mainly for the thermal treatment, annealing, hardening and sintering of low carbon steel.
|Methanol cracker (SinceGas)|
In order to remove carbon monoxide and carbon dioxide and therefore purify hydrogen (H2), so-called Pressure Swing Adsorption (PSA) is used.
Due to different adsorption properties of different gases it is possible to separate them.
Depending on the implementation, it is also possible to separate other gases such as nitrogen or oxygen.
To separate carbon monoxid and carbon dioxid from hydrogen in order to generate high-purity hydrogen, porous materials such as molecular sieves or zeolite are used. At certain pressures, the gas mixture flows through the molecular sieve designed for this application. Due to the stronger interaction of hydrogen with the molecular sieve, hydrogen is collected on the surface of the molecular sieve. The other gases (CO, CO2), are not adsorbed. After the molecular sieve has reached its capacity limit, the gas flow is diverted to another molecular sieve. Using pressure reduction and the associated significantly weaker interaction between molecular sieve and hydrogen, the now purified hydrogen can be released from the first molecular sieve. After the hydrogen removal, the first molecular sieve is available for purification again. The system is controlled by a Siemens program logic control (PLC). Therefore continuous purification is possible.
|PSA Hydrogen Purification (SinceGas)|