Steam superheater
Process for the production of ammonia from a hydrocarbon feedstock all steam produced in the waste heat boilers of the reforming and ammonia section of the plant is superheated in one or more steam superheaters located downstream the ammonia converter in the ammonia section of the plant. There is no need for steam superheater (s) in the reforming section of the plant to cool the synthesis gas. A steam superheater for use in the process is also provided. The superheater comprises two compartments in which the first and second compartments are connected in series with respect to the steam flow and in parallel with respect to the process gas flow.
1. Steam superheater ( 30 ) comprising:
first and second compartment ( 301 , 302 ), in which the first compartment ( 301 ) is provided with a shell ( 305 ), a tube sheet ( 303 ), a rear end ( 307 ), tube bundle ( 309 ), baffle plates ( 317 ), and steam inlet ( 315 ) adapted to shell ( 305 ), and in which the second compartment ( 302 ) is provided with a shell ( 306 ), a tube sheet ( 304 ), a rear end ( 308 ), tube bundle ( 310 ), baffle plates ( 317 ), and steam outlet ( 316 ) adapted to shell ( 306 );
a transition compartment ( 311 ) that separates the first and second compartment and which is defined by a space in between tubesheets ( 303 , 304 );
a channelling pipe ( 312 ) passing through tubesheets ( 303 , 304 ) and thereby through the transition chamber ( 311 ) and which extends from the first compartment ( 301 ) to the second compartment ( 302 ) along the length axis ( 320 ) of the steam superheater ( 30 );
a separation wall ( 321 ) positioned between inlet chamber ( 318 ) and outlet chamber ( 319 );
said transition compartment ( 311 ) is provided with process gas inlet ( 313 ) which extends into inlet chamber ( 318 ) of the transition compartment, the inlet chamber ( 318 ) being confined between the wall of channelling pipe ( 312 ), the wall of tubesheet ( 303 ) on the one side and into which tube bundle ( 309 ) of the first compartment ( 301 ) extends, and the wall of tubesheet ( 304 ) on the opposite side and into which tube bundle ( 310 ) of the second compartment ( 302 ) extends;
said transition compartment ( 311 ) is provided with process gas outlet ( 314 ), which extends from outlet chamber ( 319 ) of the transition compartment, the outlet chamber ( 319 ) being confined between the wall of channelling pipe ( 312 ), the wall of tubesheet ( 303 ) on the one side and into which tube bundle ( 309 ) of the first compartment ( 301 ) extends, and the wall of tubesheet ( 304 ) on the opposite side into which tube bundle ( 310 ) of the second compartment ( 302 ) extends; and
wherein the first and second compartments 301 , 302 are connected in series with respect to the steam flow and in parallel with respect to the process gas flow.
2. Steam superheater according to claim 1 , wherein the outlet chamber ( 319 ) further comprises valves ( 322 , 323 ) arranged therein and which are in direct fluid communication with tube bundles ( 309 , 310 ) of the first and second compartment ( 301 , 302 ).
3. Steam superheater according to claim 1 , wherein the tube bundle in the first compartment is made of low alloy steel and the tube bundle in the second compartment is made of stainless steel.
4. Steam superheater according to claim 1 , wherein the orientation of the steam superheater is vertical and the first or second compartment further comprises at its rear end a water outlet for the removal of accumulated water.