| 摘要 |
#CMT# #/CMT# A procedure for replacing tubes in a hydrocarbon reformer furnace involves measuring diametral expansion,taking X-rays and making surface replicas before starting a new production campaign and then replacing tubes if the diametral expansion is more than 3%,the X-ray picture shows at least one crack and/or the replica indicates thermal ageing and/or creep damage. #CMT# : #/CMT# A procedure for replacing tubes in a reformer for hydrocarbons or other sources of carbon and hydrogen using a combustion chamber with burners and catalyst-filled tubes through which passes a mixture of hydrocarbons and vapor,the burners being mounted so as to transfer their heat to the mixture through the tube walls. The method involves (A) carrying out the following before starting a new production campaign: (a) measuring the diametral expansion (delta D) of the tubes,where delta D = (Dt - D0)/D0 x 100,D0 = the diameter of the new tube and Dt = diameter at the time of measurement,(b) taking X-ray pictures of the tubes and (c) taking replicas (impressions) of the tube surfaces and then (B) replacing a tube as soon as it meets one of the following conditions: (d) delta D is more than 3%,(e) the X-ray shows at least one crack,(f) the replica indicates thermal ageing such that no secondary precipitates are observed among the primary precipitates and/or creep damage as shown by the presence of chains of cavities and/or grain boundaries,(g) it has been used for at least 5 years. #CMT#USE : #/CMT# In reforming units for hydrocarbons or other sources of carbon and hydrogen,e.g. bio-methanol. #CMT#ADVANTAGE : #/CMT# Enables the replacement of reformer furnace tubes so as to avoid their unexpected rupture when in operation. #CMT#CHEMICAL ENGINEERING : #/CMT# Preferred Procedure: Test (a) involves measuring delta D for each tube in the combustion chamber,preferably over the entire length of the tube; if delta D is between 2 and 3%,at least one of the tubes is removed for destructive analysis. For side-fired reformers,X-rays are taken at the level of the lowest weld in the hottest part of the reformer,preferably on 5% of all the tubes. If a tube is replaced after taking X-rays,further X-ray pictures are taken on another 5% of the tubes before starting a new campaign. Surface replicas are made for the section of tube which is subjected to the highest temperatures during production,preferably on 5% of all tubes; if a tube is replaced after this,the process is repeated on another 5% of tubes before starting a new campaign. |
