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This document contains information affecting the National Defense of the United States within the meaning of the Espionage Act, 50 U.S.C., 31 and 32, as amended.  Its transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law.

T.A.C. Report SnMc-10

(T.O.M. Report No. 37)

Report on Fischer-Tropsch Catalyst Ovens and General Information on the Fischer-Tropsch Process Obtained at Offices of Guteh Offnungshuette A.G., Sterkrade, Ruhr

Reported by

Capt. C. C. Hall, U.K.

June 30, 1945

Information Supplied by the 

U.S. Government Technical Oil Mission

Submitted for Distribution 
by the

Petroleum Administration for War

September 25, 1945

to the

Technical Advisory Committee
(A Subcommittee of the Technical Committee)

of the

Petroleum Industry War Council

The Offices of Guteh Offnungshütte A. G. (G.H.H.) Sterkrade, Ruhr

Reported by

Capt. C. C. Hall

on behalf of

British Ministry of Fuel and Power
United States Technical Industrial Intelligence Committee


CIOS Black List Item

June 30, 1945

Combined Intelligence Objectives Subcommittee

G-2 Division, SHAEF (Rear) APO 413

Table of Contents

Subject Page
Object of Visit 1
General 1
Fischer-Tropsch Catalyst Ovens 1
General Information on the Fischer-Tropsch Process 3

Personnel of Team

Dr. A. R. Powell, U.S. Petroleum Administration of War
Lt. Col. A. Parker, Br. Ministry of Fuel and Power
Lt. Col. R. N. Quirk, Br. Ministry of Fuel and Power
Lt. Col. H. Hollings, Br. Ministry of Fuel and Power
Capt. R. A. A. Taylor, Br. CAFT.
Capt. C. C. Hall, Br. Ministry of Fuel and Power

Target visited on April 9 and 10, 1945.

Target 30/11.10

Office of Gutehoffnungshütte A. G., Sterkrade

Object of Visit:

To obtain information and engineering drawings appertaining to reaction vessels for the Fischer-Tropsch Synthesis.

Personnel Interrogated:

Herr Mühl, Director of the Offices.
Dr. Otto Zechetmayer, Chief Chemist.
Herr Weiss, Manager of the Boiler-Making Dept.


Herr Mühl explained that the Company has a mining section with 500,000 tons/year coal output with collieries at Sterkrade, Hugo, Oberhausen, Osterfeld and Jacobi, the last two including coke-oven plants.  They operated iron works at Oberhausen with blast furnaces, rolling mills, etc., wire-mills at Gelsekirchen, and factories making rivets, screws, blades, etc., at Schwerte, general machinery at Düsseldorf and Sterkrade, steel structures, bridges, mining machinery, boilers compressors, etc., at Sterkrade.  Reaction vessels (catalyst ovens) for the Fischer-Tropsch process were made only in the boiler section at Sterkrade.

Fischer-Tropsch Catalyst Ovens

Dr. Zechetmayer stated that the manufacture of Fischer-Tropsch ovens was in the control of a "ring" of firms, Mannesmanne Rohrwerke, Kurpps and G.H.H. Mannesmanne were the leaders of this ring and had made the largest number of ovens.  He (Z) knew of only three types of ovens, (1) the normal "Lammellenofen" for use at atmospheric pressure, which had been produced in many different models differing only in minor details, such as the method of interconnection of the water tubes.  They were coupled to a common steam drum in blocks of 2, 3, or 4 ovens.  It was preferable for each oven to have its own steam drum.  (2) The double-tube oven for medium-pressure, cobalt-catalyst synthesis as seen at the Ruhrchemie plant.  (3) The double-tube oven designed for use at 20 atmospheres pressure for the iron-catalyst synthesis.  These were of the same dimensions and catalyst capacity as number (2).

Z. identified the single, odd-type oven even at Sterkrade as the "Drucklammellenofen" referred to in the S.I.C.S. correspondence.  This was a Lurgi idea and was an attempt to adapt the normal-pressure tube-and-plate oven for operation up to 20 atmospheres pressure, by giving the external case greater mechanical strength through the use of curved sections.  The required more steel for the same catalyst capacity and took a month to construct.  During such a period, 4 to 6 of the double-tube ovens could be constructed.  It had only been tried out with a cobalt catalyst, with (he believed) disappointing results.

The single medium-pressure oven with the annular "bulge" near the top, also seen in the oven house at Sterkrade, was apparently a Mannesmanne idea, the "bulge" being a self-contained steam-drum with the object of allowing individual ovens to be taken off steam.  Z. stated that although in the early days forced circulation by pump had been used on the water system of the ovens, circulation in all ovens now depended only on thermal convection.

Herr Weiss then described the construction of the double-tube oven for medium-pressure synthesis.  The inner tube was a piece of seamless, mild steel 20/24 m.m. tube on to which two T-shaped end pieces, which had been drilled out of solid metal, were welded.  The completed inner tube was then welded into the outer tube (44/48 mm.) and the assembled "double-tube" welded into the tube plates.  The arrangement is shown in the accompanying sketch.

In order to maintain the inner tube in a central position within the outer tube, solid metal distance-pieces were welded to the outer wall of the inner tube at intervals, longitudinally and circumferentially. 

The adaptation of this oven, which was designed for a maximum gas pressure of 15 atmos., for operation up to 25 atmos. gas pressure for iron-catalyst synthesis had been achieved by Weiss, merely by increasing the strength of the welded joints, thus:-

S = D.p.x.   where
      200 k2y
S = thickness of tube wall
D= int. diam. of tube
p = pressure
For p = atms., x = 4.5 x = factor of safety
y = 0.7 k2 = strength of material
For p = atms., x = 4.0 y = welding factor
y = 1.0

Each oven contained 2100 double-tubes.

Engineering drawings of the normal-pressure and medium-pressure ovens were obtained and sent through as Official Documents.

General Information on the Fischer-Tropsch Process

Zechetmayer stated that no full-scale trial of the iron catalyst had been made in Germany, and if the S.I.C.S. plant had been completed it would have been the first of this type.  This had arisen because the German Government had decreed (in 1941 or 1942) against the erection of further Fischer-Tropsch plants.  All the existing plants had, in fact, been in operation before the war.  All the plants follow the Ruhrchemie model but several of them have experimental units.  He instanced Rheinpreussen who had an experimental plant for operating in the liquid phase.

The use of recirculation of residual gas was a Lurgi idea and was being energetically developed both of cobalt and iron catalysts.  The Lurgi "diluted catalyst", however, was merely a "patent racket" and had not been adopted.

If the Feinreinigung step is to be carried out on the compressed gas (as was the case in the S.I.C.S. project), the same contact is used in the same type of vessel strengthened to withstand the operating pressure.

The partly-constructed toluene-from-heptane plant at Sterkrade had been ordered by the Wehrmacht.  It was to have produced 10,000 tons of toluene per annum and would have cost 40 x 106 RM.  The catalyst was to operate at 500º C. in the tall-brick-lined towers seen at Sterkrade.