Heat exchanger

1. A heat exchanger comprising:

an outer cylinder having a cylindrical shape with both ends closed;

a tube plate partitioning, at a position close to a first end of the both ends, an inside of the outer cylinder into a tube-interior fluid chamber on a side where the first end is located and a tube-exterior fluid chamber on a side where a second end is located;

a plurality of heat transfer tubes arranged in the tube-exterior fluid chamber and including at least one end that is fixed to the tube plate and faces the tube-interior fluid chamber; and

a partition wall partitioning the tube-exterior fluid chamber into a first tube chamber, in which an inlet side tube group is present as a collection of inlet side tube sections extending from inlet ends of the plurality of heat transfer tubes, and a second tube chamber, in which an outlet side tube group is present as a collection of outlet side tube sections extending from outlet ends of the plurality of heat transfer tubes, wherein

the tube plate includes

a tube plate base material to which end sections of the plurality of heat transfer tubes are fixed,

a first backplate covering a surface of the tube plate base material on a side where the first tube chamber is located, and

a fastener that includes at least a shaft section and is configured to fix the first backplate to the tube plate base material;

the first backplate includes

heat transfer tube insertion holes through which the plurality of heat transfer tubes are inserted, and

an insertion hole through which the shaft section is inserted;

the first backplate is joined to an end section of the partition wall on the side where the first end is located;

the partition wall, the first backplate, and the fastener are formed of a material having a higher corrosion resistance than the tube plate base material;

the heat exchanger further comprises:

an inner cylinder arranged in the tube-exterior fluid chamber and covering the plurality of heat transfer tubes and the partition wall;

a space partition member that is disposed between the outer cylinder and the inner cylinder and that partitions a space between the outer cylinder and the inner cylinder on the side where the first tube chamber is located into the side where the first end is located and the side where the second end is located;

a first nozzle stub provided in the outer cylinder at a position closer to the second end than to the space partition member on the side where the first tube chamber is located with respect to the partition wall or at a position on a side where the second tube chamber is located with respect to the partition wall; and

a second nozzle stub provided in the outer cylinder on the side where the first tube chamber is located with respect to the partition wall and at a position between the space partition member and the tube plate,

the inner cylinder is open on the side where the first end is located and is closed on the side where the second end is located;

the partition wall is joined to the inner cylinder to divide the inner cylinder into two sections in a radial direction to form the first tube chamber and the second tube chamber;

the space partition member is joined to an outer peripheral surface of the inner cylinder and is displaceable with respect to an inner peripheral surface of the outer cylinder without being joined to the inner peripheral surface of the outer cylinder; and

the inner cylinder and the space partition member are formed of a material having a higher corrosion resistance than the tube plate base material.

2. The heat exchanger according to claim 1 , comprising a second backplate that is disposed to cover a region between the space partition member and the tube plate on the side where the first tube chamber is located in the inner peripheral surface of the outer cylinder and that is formed of a material having a higher corrosion resistance than the outer cylinder.

3. The heat exchanger according to claim 1 , comprising a first seal that is disposed to extend between the inner peripheral surface of the outer cylinder and either one of a surface, on the side where the first end is located, and a surface, on the side where the second end is located, of the space partition member and that closes a gap generated between the space partition member and the inner peripheral surface of the outer cylinder while allowing the space partition member to be displaceable with respect to the outer cylinder.

4. The heat exchanger according to claim 1 , comprising a second seal that is disposed to extend between the inner peripheral surface of the outer cylinder and either one of a surface, on the side where the first tube chamber is located, and a surface, on the side where the second tube chamber is located, of the partition wall and that closes a gap generated between the partition wall and the inner peripheral surface of the outer cylinder while allowing the partition wall to be displaceable with respect to the outer cylinder.

5. The heat exchanger according to claim 2 , wherein the second backplate is divided into a plurality of sections along the inner peripheral surface of the outer cylinder.

6. The heat exchanger according to claim 1 , wherein the second nozzle stub is formed of a material having a higher corrosion resistance than the outer cylinder.

7. The heat exchanger according to claim 1 , wherein the fastener includes a washer that has an inner diameter larger than an outer diameter of the shaft section and smaller than an inner diameter of the insertion hole and that has an outer diameter larger than an inner diameter of the insertion hole.

8. The heat exchanger according to claim 3 , wherein the first seal is formed in a sheet shape elastically deformed so that a concave surface is disposed on a side in which pressure is relatively high.

9. The heat exchanger according to claim 4 , wherein the second seal is formed in a sheet shape elastically deformed so that a concave surface is disposed on a side in which pressure is relatively high.