Introduction
Hydrogen is becoming a hotter and hotter topic. Do you know how hydrogen is produced? One popular method to produce hydrogen is through a steam methane reforming process.
Overview
Generally speaking, there are 6 process modules to produce hydrogen. First methane and steam react in the heating & reaction module, then it is cooled to ambient temperature before sending to a Pressure Swing Adsorption or PSA module to get the pure hydrogen. The final step is to compress hydrogen to the required pressure. Along with the 4 main process modules, we also need to have a steam module to produce steam and a flue gas module to provide all the heat needed in the process.
Methane feed is first split to 2 parts. The major part will be converted to hydrogen and the other part will be burned to provide the heat required. I will first go through the 4 main process modules and then come back to the 2 utility modules.
Heating & Reaction Module
In the heating & reaction module, methane is mixed with the recycled hydrogen, then it is preheated to about 750 F. Because H2S is a serious killer to the reformer catalyst, so it is removed before mixing with steam. Steam and methane mixture is further heated before entering the reformer. There are 2 main reactions in the reformer. Ethane and the heaviers are reformed in the Pre-Reformer. Then methane is reformed in the Main Reformer. During the reforming process, a large quantity of CO is produced. So we need to have a CO Shift process to convert CO to CO2 and produce more hydrogen. CO shift process favors lower temperature, so the gas mixture is cooled to produce steam before entering the CO Shift reactor. After the CO Shift reactor, the main components in the stream are hydrogen, water vapor and CO2. The next two modules are used to remove water and CO2. The mixture is cooled against the incoming feed before going to the cooling module.
Cooling Module
The cooling module is primarily used to remove water. At the same time, the heat is used to generate steam. The mixture gas is further cooled in steam generator coil 2, then boiler feed water preheater, then makeup water preheater. Liquid water is separated out in the separator. Then the gas is further cooled to ambient temperature to further remove liquid water before going to the PSA module.
PSA Module
The PSA module is primarily used to remove contaminants to get pure hydrogen.
Compression Module
The final module of the 4 major process modules is compression. It utilizes compressors to compress hydrogen to the required product pressure.
Steam Module
The steam module is used to produce steam. The heat for BFW Preheater comes from the product gas mixture. The heat for steam generator comes from the steam generator coil 1, 2 and 3. The steam is further super-heated by flue gas after blowing down small quantity of water. Then part of the steam reacts in the reformer and the other part of the steam is exported.
Flue Gas Module
The last module of the 6 is the flue gas module. The fuel gas and preheated air are burned in the fired heater to provide the heat for reformer reaction. Then it is cooled down in a series of heat exchangers. The flue gas is first used to preheat the steam methane mixture before entering the reformer, then it is used to super-heat steam, preheat air, generate steam and preheat air again before vented to the atmosphere through a blower.
More to explore
This concludes the 6 modules to produce hydrogen in a steam methane reformer. Thanks for watching this video. It is brought to you by Guofu Chen. More interesting topics can be found at showcase.guofuchen.com
