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We have naptha hydrotreater unit. At present unit is under construction phase and unit is being commissioned. We are going to be processing full range naphtha (C5 to 160 deg c) in our naphtha hydrotreater. What would be the recommended reactor inlet temperature and operating pressure for fresh feed cut in to reactor during normal start up?
 
Answers
13/11/2017 A: Adi H, Qpr, Syd.adi28@gmail.com
The chloriding agent used in fixed bed semiregenerative platforming unit is TCE mixed with platformate to be injected in the system. Is there any issue with mixing it with the run down platformate to the catalyst. Another question, what are the factors to be considered when changing the chloriding agent for example PERC ? Is there any impact ?
24/09/2009 A: Randy Alexander, EURECAT, randy.alexander@eurecat.com
Our company provides pre-activation (presulfiding) services for a large percentage of the NHT units in North America. As others have stated, operating pressure will depend on the unit design and the type of feed being processed. With the NHT startups we are involved in, the inlet temperature of the feed is always high enough to convert the feed to the vapor phase. This is usually above 450F (230C).
Our pre-activation service, called Totsucat, allows you to avoid the sulfiding step, saving a considerable amount of production time. Additional benefits of Totsucat preactivation are: no sour water make, no additional hydrogen required, no HSE issues associated with handling sulfur chemicals such as DMDS or DMS, no risk of damaging the catalyst with H2 reduction prior to sulfiding.
21/09/2009 A: Kamaljit Medhi, Indian Oil Corporation Ltd, medhik@indianoil.in
I think your query is not backed up by sufficient information about your unit and type of catalyst. The best answer you will find in the process licensor's operating instruction book as the same has been prepared based on your sulphur, Nitrogen and other impurities. Also you have not mentioned if the Naphtha is a Straight run product or you are also processing cracked stream. If the impurities is very less for naphtha being from very sweet crude and also of small capacity, your HDT may be a once through process with pressure about 11-12 Kg/cm2g and temperature around 300 degC. However if you are using Naphtha with diolefins, you must use some good catalyst to take care of the diolefins(Ni-Mo catalysts are very affective) and also silica trap if you are processing Coker Naphtha.
Most likely you are having a recycle compressor. Also in the first start up you need to carry out sulphiding of the catalyst with DMDS and must follow the detail procedure given by the Licensor. The normal start up temperature may vary from 250-300 degC and similarly pressure from 30-35 bar. But you must check with the process licensor's instruction book to find out the recommended parameters.
21/09/2009 A: Alan Goelzer, Jacobs Consultancy, alan.goelzer@jacobs.com
Technology supplier for the Naphtha Hydrotreater Unit should have provided a base operating pressure either at the primary hydrotreating reactor inlet or at the cold high-pressure separator. All normal operations including start-of-run should be at this pressure. Note normal operations must be preceded by pre-sulphiding protocol.
Technology supplier should have provided a treat gas flow (Nm3/hr or SCFD) based on rated BPSD or Sm3/hr total oil feed going through the HP feed pump.
Technology supplier should also have provided an RxT,inlet-sor for the primary HT reactor. This tempreature should ensure 100% vaporization of the mixture of treat gas and naphtha feed by either entry into the HP Charge Heater or entry into the radiant zone of the HP Charge Heater.
20/09/2009 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Pressure and operating temperature for NHDT depend on feed qualities and type of catalyst employed. For straight run naphtha the operating pressure may be in the range of about 20 to 30 bar. hydrogen partial pressure is about 6 bar. For cracked stocks the pressure may be higher. A limit in minimum cut in pressure is specified by licensor for catalyst protection
Operating temperature is function of LHSV too and normally is range of 260 to 280 degree C at SOR. Cracked stocks may need higher temperature with suitable catalysts in the reactor.
20/09/2009 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Operating pressure depends on the plant design. Normal operating pressure for straight run naphtha (SRN) may be in the in the range of 20 to 30 bar. Hydrogen partial pressure required are about 6 bar for SRN. Feed cut in pressure depends on availability of hydrogen too and are specified by process licensor / catalyst vendor.
Likewise normal operating reactor inlet temperature are dependent on the feed quality of SRN and percentage of thru'put. It may be as low as 260 to 280 degree C and is raised depending on sulfur or nitrogen content in product. For the feed containing cracked stocks pressure and temperature may be higher. Likewise catalyst may also be chosen accordingly