APPARATUS FOR PROCESSING HIGHLY CORROSIVE AGENTS

1 . An apparatus for treating highly corrosive agents, comprising:

a tube bundle heat exchanger, structured to carry out a heat exchange between a first fluid which is highly corrosive and flowing inside of at least one tube bundle, and a second fluid flowing outside of said at least one tube bundle,

wherein said at least one tube bundle comprises at least one tube of titanium or titanium alloy, having a layer of zirconium or zirconium alloy bonded to the titanium or titanium alloy tube metallurgically or through welding,

wherein said at least one titanium or titanium alloy tube is coated on the inside by said zirconium or zirconium alloy tube, and said zirconium or zirconium alloy layer in contact with said first highly corrosive fluid flowing inside said at least one tube bundle, and said titanium or titanium alloy tube is in contact with at least said second fluid flowing outside said at least one layer bundle,

wherein said at least one titanium or titanium alloy tube and said zirconium or zirconium alloy coating layer are bonded together through hot-drawing.

2 . The apparatus according to claim 1 , wherein said at least one titanium or titanium alloy tube has a thickness between 1.0 and 10 millimeters, and in that said zirconium or zirconium alloy coating tube has a thickness between 0.3 and 2.0 millimeters.

3 . The apparatus according to claim 1 , wherein said at least one titanium or titanium alloy tube is only partially coated with said zirconium or zirconium alloy layer.

4 . The apparatus according to claim 3 , wherein said zirconium or zirconium alloy layer coats solely an end portion of the at least one titanium or titanium alloy tube.

5 . The apparatus according to claim 4 , wherein said zirconium or zirconium alloy layer extends in said at least one titanium or titanium alloy tube starting from an entry end towards an opposite end thereof, for a portion between 5 and 30 percent.

6 . The apparatus according to claim 1 , wherein said heat exchanger comprises respective upper and lower tube plates for supporting said tube bundle, said tube plates being made of titanium or titanium alloy, or being coated with a titanium or titanium alloy layer.

7 . The apparatus according to claim 6 , wherein said upper and lower tube plates are made of carbon or stainless steel, coated on the outside with a layer of 3-15 millimeters of titanium or titanium alloy.

8 . The apparatus according to claim 1 , wherein the apparatus is a stripper for the decomposition of ammonium carbamate in an urea production plant.

9 . The apparatus according to claim 1 , wherein the apparatus is a condenser for the condensation of ammonia and carbon dioxide into ammonium carbamate in an urea production plant.

10 . An apparatus for treating highly corrosive agents, comprising:

a tube bundle heat exchanger, structured to carry out a heat exchange between two fluids one of which is highly corrosive and flowing inside of at least one tube bundle,

wherein said at least one tube bundle comprises at least one titanium or titanium alloy tube, coated with a layer of zirconium or zirconium alloy bonded to the titanium or titanium alloy tube metallurgically or through welding,

wherein said zirconium or zirconium alloy layer extends inside said at least one titanium or titanium alloy tube starting from an entry end towards an opposite end thereof, for a portion between 10 and 20 percent of the length of the titanium or titanium alloy tube.