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For how long we can run the hydrotreater in recycle mode , if less feed is available?
 
Answers
14/04/2016 A: Sarath Konda, DuPont India, sharathsatya@gmail.com
HT can be operated in a recycle mode, Combined Feed rate ( Recycle + Fresh Feed) should be adequate to maintain a sufficient mass flux across the reactor to avoid channeling being created which could create High Radials issue in the beds. Kindly Note operating unit in a recycle mode is a loss of energy and may incur unnecessary operating cost. if the unit is having only a stripper and product run down to tanks, build -up of PNA will be minimal as there is continuous outflow of product/heavy material.
08/02/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
There is no problem in running the hydrotreater at the specified turn down ratio. The answer depends on the the type of feed stock, sulfur in feed, desired product sulfur and state of catalyst
04/02/2016 A: NS Murthy, Suez, murthy.ns.ext@suez.com
Normally HTs can be operated at 40 to 50% of design intake as turn down operation. With same recycle gas quantity, lower feed implies higher H2 to Oil ratio and least catalyst deactivation. It would be better to get to planning / scheduling process which is forcing lower feed availability for HTs rather than under utilizing the assets.
04/02/2016 A: Prashant Parihar, BPCL, pariharprashant@bharatpetroleum.in
You need to choose a recycle ratio of recycle/fresh feed to avoid build up of PNA's and refractory compounds in feed to hydrotreater. Dilution of feed would require optimization of process conditions. More ever concept of recycling of hydrotreated feed is advocated and practiced in Isotherming process by Dupont. In view of this, unit can be operated in recycle mode while monitoring usual process parameters along the catalyst run length.