Patent ID: 11939544
Assignee: NOVA CHEMICALS (INTERNATIONAL) S.A.
Field: Basic materials chemistry (Chemistry)
Classification: CPC C | IPC C

Claim 10:
11. A method of treating a reactor, comprising:
performing a decoking air burn on the reactor until air leaving the reactor has a total carbon oxide content less than 2,000 parts per million (ppm), wherein the reactor in operation converts chemicals feedstock at a temperature greater than 700° C.;
scouring a reactor surface with steam at a steam scour rate of not less than 2500 kg/hour/reactor for a time from 0.5 to 10 hours to give the reactor surface as a scoured reactor surface, wherein the decoking air burn is performed prior to the scouring, and wherein the reactor surface and the scoured reactor surface are stainless steel having less than 38 weight % of chromium or wherein the reactor surface and the scoured reactor surface are an alloy having less than 20 weight % of chromium, the alloy being a nickel based alloy or a cobalt based alloy; and
nitrogenating the scoured reactor surface by treating the scoured reactor surface with a mixture comprising steam and nitrogen in a weight ratio of the steam to nitrogen from 20:1 to 30:1 with an amount of the mixture from 80 to 110 kg/hour per reactor at a temperature from 750° C. to 850° C. for a time not less than 20 minutes, in the absence of added oxygen except for oxygen present in the steam and in the nitrogen, wherein the steam comprises less than 10 parts per billion (ppb) of oxygen and the nitrogen comprises less than 5 ppm of oxygen, wherein the mixture does not comprise an anti-coking agent, wherein the method of treating the reactor does not comprise treating the reactor with a chemical to reduce coking.