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Production of Hydrogen from Lpg

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Production of Hydrogen from Lpg

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  • November 2008
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2.5.1. Processing Steps of Hydrogen Production from LPG

Conventional process for producing hydrogen from light hydrocarbons involves the following process steps:

• Feed preparation
• Sulfur removal
• Steam reforming
• CO shift conversion
• Autothermal reforming
• Process gas cooling
• Synthesis gas purification (PSA pressure swing absorption) [5]

2.5.1.1. Sulfur Removal
LPG feed first passes through an ambient temperature sulfur adsorption vessel. The proprietary adsorbent in this vessel has been specifically designed to remove sulfur species native to LPG feeds as well as those sulfur compounds that are added as odorants for leak detection. The sulfur adsorbent has been proven effective in removing compounds ranging from H2S and mercaptans to thiophenes. Since sulfur is known to affect the performance of all reforming catalysts, removing the sulfur prior to entering the reforming section ensures the highest level of reforming catalyst performance and maximum catalyst life. [5]

2.5.1.2. Autothermal Reforming
During the reforming step, LPG feed is converted into a hydrogen rich product stream. At the entrance of the reforming catalyst bed, the feed, air and steam are mixed in proportions that are chosen to maximize hydrogen production from the given feedstock. The conversion takes place over a bi-functional catalyst that promotes both partial oxidation and steam reforming reactions in the same catalyst bed. This results in a direct transfer of heat within the catalyst bed and efficient production of hydrogen. The direct transfer of heat also means the process is responsive to changes in hydrogen demand requirements. [5]

3. Hydrogen Purification
Hydrogen purification is performed via the use of Pressure Swing Adsorption (PSA) technology. The PSA technology employed by HyRadix combines novel process hardware technology with proprietary adsorbents to attain a very high recovery of the product...