US2014189A - Apparatus for cracking hydrocarbons - Google Patents

Description

Patented Sept. 10, 1935 I UNITED srA'rEs PATENT OF ICE APPARATUS FOR CRACKING muocaanous Hermann Josef Schifller, Dusseldorf, Germany, assignor to the firm Vereinigte Stahlwerke Aktiengesellschaft, Dusseldorf, Germany No Drawing. Application August 19, 1931, Serial No. 558,189. In Germany August 27, 1930 2 Claims. (Cl. 196-133) It has been the practice in processes for crackum for raising the resistance to corrosion. The ing hydrocarbon liquids to employ high pressures .following steel alloys are given as samples comand temperatures with a view tosecure high bined according to the invention:

yields of the products of cracking and to ensure 5 economy. Thetemperatures employed in such v v 5 cracking processes are partly above the scaling ,SteelNo. Mn Cr Al Mo Ti limit of ordinary materials employed for those parts of cracking apparatus subjected to high pressures and temperatures, such as soft carbon- 4 )0 steels. There is thus a need for great resistance i 8;; 3 it 1 12 31% "(iii 10 to deterioration of the metal used forsuch parts 12 0,15 0,3 10 as 1.2 0,5 0.1 Be

of cracking apparatus.

Furthermore the material employed must be highly resistant to chemicals, as both crude oils When temperatures are employed which lie above I and tarry residues commonly contain sulphur the scaling limit it is not necessary-to consider 15 compounds (in relatively large quantities) to v not only a high hot tensile limit, but also to take which some steels are highly sensitive.- into account the necessary resistance to seal- In order to reach the degree of resistance re- 'i 11? has been found y the applicant h quired in the parts of apparatus that are subthe alloys that satisfy these requirements are jected to high pressures and temperatures, althose whose chromium content lies between 5% go I loyed steels are employed, among them being and 8%, and whose aluminium content lies bechromium-nickel-steel. Steels containing nickel tween 0.3% a a wh rmo e 00 have however proved to be sensitive to sulphur ,tain'small quantities of silicon and molybdenum. and they exhibit'rnore particularly at high pres- Such a loy a resistant to s a p to about sures and temperatures, phenomena of brittle- 900 0., they have a high hot tensile limit, and g5 nesswhich may result in the fracture of the they are highly resistant to sulphur. If the cracking tubes. Moreover nickel is known to process be carried out at temperatures whichlie favour the undue production of soft carbon inbelow the scaling limit the quantities of chrosuch and similar apparatus. mium used may be reduced to about 2%.

. Experiments carried out by theapplicant have Thus according to the invention the cracking demonstrated that the parts of apparatus used 4 of hydrocarbon liquids is efiected in an apparatus for cracking hydrocarbon liquids, when made of in which the parts subjected to high temperasteel alloys are suitable when the metal contains tures and pressures are made of steel alloys which a substantial proportion of chromium-andis subwhile they contain chromium do not contain stantially free from nickel. The invention thus nickel. .comprises the use of ,such steel alloys for the The invention comprises the use of a process in purpose. which the steel alloys employed for the parts of For the purpose moreover the chromium con-'- the apparatus have a chromium content up to 8% tent in such steel alloys may advantageously be and at the most 13%. a as high as 7%, and in special cases even up The invention also comprises a small addition 0 to 13%. If still smaller quantities of aluminium of aluminium to the material so employed, and be added to the chromium alloys the resistance the additions of other substances as hereinbefore to the action of sulphur and sulphur compounds indicated, and an apparatus whose parts are made is increased. The aluminium content necessary of steel alloys having the characteristics indito produce this result lies between 0.8% and 4.0%. cated. A further improvement in the quality of the steel I wi be understood t the invention is is obtained by the addition 01' elements, such as broadly appli to Processes for crackinahysilicon, molybdenum, vanadium, titanium, beryldleeelben liquids, either in the liquid v p ur lium, in quantities about 0.1% to 2%. Silicon phase, or partly in the liquid and partly in the may be added in order to improve the metallurgic -D Phase, it being understood t h m manufacture in regard to the deoxydation and f the cracking or r a tubes. the re the degasifying oi the steel. Molybdenum and or reaction, receiving, expansion or other vessels vanadium are able to raise the resistance to dethrough whichth hyd b n liquids flpo terioration in hot state. Titanium is added for pass at high pressures and high temperatures improving the structure of the grain and beryllior otherwise while subject to the conditions of the beryllium 0.1% to 2%, the balance substantially iron.

2. Apparatus for cracking liquid hydrocarbons comprising a part of tubular form, means for supplying hydrocarbons thereto, and imparting heat at cracking temperature, the said part consisting of a steel alloy tree from nickel and containing chromium 5% to 13%, aluminum 0.3% to 4%, beryllium 0.1% to 2%, silicon 0.2% to 2%, molybdenum 0.3% to 2% and the balance 10 substantially iron.

HERMANN VJOSEF SCHH'FLER.