Why do we need to maintain gas oil ratio in our diesel hydrotreater?
Answers
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25/07/2017
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Bhavesh Kanani, SPIE Oil and Gas, bhavesh.kanani@gmail.com
The H2/HC ratio, at the reactor inlet, is the ratio of pure hydrogen in the recycle gas (excluding make-up) in Sm3/h to the fresh feed flow rate (m3/h at 15°C). The amount of hydrogen supplied in the reaction includes the hydrogen that will be consumed by chemical reaction and an excess of hydrogen necessary to obtain sufficient hydrogen partial pressure and therefore a constant excess of Hydrogen that allows minimization of coke formation. This ratio can be modified by changing the high-pressure purge or the recycle rate compressor speed.
Maintaining proper hydrogen recycle gas purity and recycle gas to feed ratios is essential for suppressing the formation of heavy condensed hydrocarbons which would subsequently deposit as coke on the catalyst. Whereas the excess hydrogen will favors the cracking and produces lighter components, losing the yield of valuable diesel product. One must monitor it closely for better control over the catalyst deactivation
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24/01/2010
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Nirav Kholiya, L&T- Chiyoda Limited, niravkholiya@gmail.com
While it is good to have high H2 concentration as explained in above answers, hydrotreating catalyst are also sensitive to higher H2 concentration than specified. if you have higher gas to oil ratio then specified, you will have higher amount of cracking and you may lose your valuable product as cracked lighter stream or naphtha during the processing of diesel. So, optimum oil to gas ratio is the key.
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02/04/2009
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Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Suitable gas to oil ratio is maintained for the following reasons:
• Provide availability of hydrogen all along the catalyst bed.
• Suppress formation of coke precursors and coke on the catalyst
• Maintain the proper mass velocity in the bed thus reducing the possibilities of channelling in the bed.
• Maintain the partial pressure of hydrogen
• Carries the reaction heat along with it. Hydrogen has high heat capacity.
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26/03/2009
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Samuel Sinanan, IPSL, Samuel.Sinanan@ipsl.co.tt
We need to maintain a healthy hydrogen to oil ratio to prevent coking and subsequent deactivation of the catalyst. As a guide the available hydrogen should be at least 3 times the hydrogen consumption for straight run feedstocks and at least 4 times the hydrogen consumption for cracked feedstocks.
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26/03/2009
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Mukesh Patel, Reliance Industries Limited, mukesh1000@yahoo.com
Gas to oil ratio indicates the Hydrogen to Oil (feed) ratio. For any hydroprocessing unit, hydrogen is very important to achieve reactions like Desulphurization, Denitrification, dearomatization etc. Higher the gas to oil ratio better for the catalyst also. Lower gas to oil ratio leads to higher deactivation of the catalyst. However, recycle gas and make up hydrogen purity and partial pressure are also equally important.
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