Q & A > Question Details
This is my NHT unit:
1 reactor with 1 fixed bed, volum 27m3, catalyst S-120 from UOP.
3 stage compressor: 4bar--> 10.5 bar--> 25 bar--> 43 bar.
Splitter 52 trays
Stripper 25 sieves trays.
If I change the feed for NHT unit from the SR naphtha with 100ppm wtS to the SR naphtha with 1230 ppm wt S ( because I changed the crude oil for DAV), what should I do to maintain the specification product for Platforming CCR (0.5 ppm S, 0.5 ppm N). And if I would like to revamp this unit for a product with 0.1 ppm wt S, what should I do?
02/01/2012 A: Rajkumar Chate, Sulzer, rajkumar.chate@sulzer.com
Reactor temperature has to be increased to convert the sulfer in to H2S. Also additional sulfer in feed will lead to increase the H2S concentration in feed to stripper. Stripper trays should also be checked with increased loads. To strioout the sulfer from the naphtha (reactor effluent after cold separator) we may need to increase the stripper reboiler return temperature and which leads to an additional vapor liquid traffic in column. Stripper existing internals adequacy shall be checked. If you increase the reactor temperature that will convert the elemental sulfer in to H2S but that sulfer will be finally removed from stripper only.
You can run the simulator generate the vapor liquid traffic across the column to meet the sulfer content in hydrotreated naphtha (feed to CCR or Alkylation) then check the vapor liquid traffic with column internal hydraulics data sheet loadings.
Gaurd bed reactor can also be installed in the upstream of alkylation or CCR to meet the sulfer content in feed.
25/11/2011 A: Satish Angadi, Haldor topsoe, satish.angadi@gmail.com
Option 1) Raise the RIT to meet the product sulfur. Use the catalyst till its cycle length. For this, I assume your MUG compressor has the capacity to add hydrogen as it is consumed. When the catalyst is exhausted specify feed sulfur= 1230 wt ppm S for the subsequent catalyst procurement.
Option 2) Your MUG compressor has limitation : then blend the feed of low S and 1230 ppm sulfur and adjust Feed, RIT to meet the platformer feed specification.
Splitter and Stripper should not pose problem.