Reformer furnace with internal recirculation

A reformer furnace having a cylindrical shell with an open outlet end in bottom of the shell, and a burner surrounded by a wall spaced apart the burner arranged within the shell and spaced apart from inner wall surface of the shell, thereby defining a reformer chamber between the burner wall and inner surface of the shell and a combustion chamber within the wall surrounding the burner. One or more reformer tubes, having an outer tube with a closed end and an open ended inner tube are arranged vertically within the reformer chamber, so that a hot flue gas from the burner circulates with an upward flow in the combustion chamber and a downward flow in the reformer chamber.

BACKGROUND OF THE INVENTION 
Steam reforming is a chemical process by which hydrocarbon and steam react 
to form hydrogen, carbon monoxide and carbon dioxide. The reaction is 
strongly endothermic. 
The reactor in which this process takes place is a reformer. 
One type of reformer consists of a furnace, equipped with a number of tubes 
filled with an appropriate reforming catalyst. Hydrocarbon and steam flow 
through the reformer tubes. Burners in the furnace supply the heat, which 
is transferred to the reformer tubes in which the endothermic reforming 
reaction takes place. 
The burners of a reformer furnace may be arranged in different ways. One of 
the best ways is to place a large number of burners on the furnace walls 
in such a way that the walls are heated and reflect this heat by radiation 
to the reformer tubes. The general object of this invention is to provide 
a reformer furnace that releases heat to the tubes from a large surface of 
uniform high temperature rather than from the small and very hot volume of 
a flame. 
SUMMARY OF THE INVENTION 
This invention provides a reformer furnace having a cylindrical outer shell 
with an open outlet at the bottom; a burner concentrically surrounded by a 
wall spaced apart from the cylindrical outer shell, thereby defining an 
annular reformer chamber between the burner wall and the inner surface of 
the outer shell and a combustion chamber within the wall surrounding the 
burner. One or more reformer tubes, having an outer tube with a closed end 
and an open ended inner tube are arranged vertically within the reformer 
chamber, so that hot flue gas from the burner circulates with an upward 
flow in the combustion chamber and a downward flow in the reformer chamber 
.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawing, the furnace 1 has one large burner 4, placed at 
the furnace bottom. The burner is surrounded by a wall 6, which is open at 
the top and has openings at the bottom. The reformer tubes 8 are placed 
outside this burner wall and inside the furnace outer wall 10. When the 
burner is in function, the flue gas from the flame will circulate around 
the burner wall 6 as shown by the arrows 12 in the Figure. The flue gas 
will have an upwards flow in the combustion chamber 14 and a downwards 
flow when it is cooled in the reformer tube chamber 16. When the flue gas 
at the furnace bottom flows through the burner wall openings 18, a part of 
it will leave the furnace as shown by arrows 20, while the main part will 
mix into the upwards flow in the combustion chamber. 
By control of the circulation rate, the temperature of the burner wall is 
adjusted to a level where uniform radiation to the reformer tubes in 
combination with the convection from the downwards flow will supply the 
necessary heat for the reforming process. 
Each reformer tube 8 has an open ended central passageway 22 surrounded by 
a catalyst bed 24 containing steam reforming catalyst. Feed to be reformed 
is fed downwardly to the central passageway and passes upwardly through 
the catalyst bed, and the product leaves from the top of the catalyst bed. 
A preferred layout provides one burner surrounded by the burner wall, which 
is surrounded by a circular arrangement of reformer tubes, which again is 
surrounded by an outer circular furnace wall. 
Another preferred layout is in the form of a multi-burner furnace with a 
number of burners, each surrounded by a burner wall in a matrix of 
reformer tubes, placed in a square or rectangular furnace. 
Although the present invention has been described in relation to particular 
embodiments thereof, many other variations and modifications and other 
uses will become apparent to those skilled in the art. Therefore, the 
present invention is to be limited not by the specific disclosure herein, 
but only by the appended claims.