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Please explain to me what the MCC (metal catalyzed coking) in a high temperature equipment of a Naphtha Platforming unit is, and how to prevent it?
 
Answers
11/03/2015 A: Farid Q Q, Indian oil corporation Ltd, faridulqadar@gmail.com
Metal catalyzed coking occurs When hydro carbons present in feed react with the process metallurgy at temperatures typically above 480 degree C. to produce carbon-containing deposits. These carbon containing deposits can build up to a level where they are detrimental to the process by creating, for example, pressure drop problems, blocking off catalytic sites, and/or impeding the transfer of heat, in for example, a furnace tube. Metal catalyZed coking is also an indication that the plant or process metallurgy is undergoing metal dusting and possibly carburization. Formation of MCC depends on factors such as severity, H2/HCBN ratio, Reactor pressure and so on. In severe cases, MCC damages the reactor internals such as scallop and centerpipe.
Best way to avoid it is to inject 0.5 wt ppm of DMDS to the reformer feed and daily check the dosing rate, also confirm the same by checking H2S in the reformer recycle gas ( typically around 1.5 ppmv).
16/06/2013 A: Gopal Swamy, PRC, gopa4swam@yahoo.com
Marcello Ferrara:
Could you share with all of us, your new technology to prevent 'Coke Formation', be it Platformers or any other Gas Cracking Furnaces. Industry experience suggests that coke formation is unavoidable. And, so is the periodic decoking, that varies from process to process, and associated downstream problems often.
21/05/2013 A: Manas Banerjee, CGM-T, manasumi@gmail.com
Also keep in control the skin temperature of the reformer heaters and interheters. The metal dusting increases if your heaters skin is persistantly high at 650+ Deg C.
14/06/2012 A: Isnandhi Saputra, PT Pertamina RU IV Cilacap, isnandhi.dwi@pertamina.com
Our refinery faced the problem a couple of time before...it is due to the metal layer become active as catalyst to crack naphta hydrocarbon. TO solve this, we inject DMDS at our reformer feed to maintain sulfur min 0.25 ppm-wt...while max sulphur should be maintained as high as 0.5 ppm-wt to avoid catalyst poisoning.
17/04/2012 A: Marcello Ferrara, ITW SrL, mferrara@itw.it
We have developed a new technology to face coke formation problems in Naphtha Platforming.