Transfer pipe for furnace

1. A transfer pipe for a furnace, comprising:

a body portion having an inlet and an outlet through which a fluid is transferred;

a guide portion having polygonal sides formed on an inner wall of the body portion and extending in a spiral form in a longitudinal direction of the body portion;

diameter change portions that repeatedly protrude in a longitudinal direction of the transfer pipe from the inner wall of the body portion in a rounded form; and

a branch passage formed on the inner wall of the body portion, wherein the branch passage is inclined with respect to the polygonal sides, so as to intersect with adjacent ones of the polygonal sides,

wherein the guide portion has an inner peripheral surface which has an N-sided polygonal cross-section in a first section and an (N−1)-sided polygonal cross-section in a second section, wherein N is a positive integer,

wherein the guide portion comprises a first guide portion extending in the longitudinal direction of the body portion from the inlet and a second guide portion extending upward from the first guide portion, and

wherein an angle of extension of the first guide portion with respect to a center vertical axis is different from an angle of extension of the second guide portion with respect to the center vertical axis.

2. The transfer pipe according to claim 1 , wherein the transfer pipe has a polygonal cross-sectional shape therein.

3. The transfer pipe according to claim 1 , wherein the guide portion extends by an angle of 360° in the longitudinal direction of the body portion to form a cycle, and the cycle is repeated along an entire length of the transfer pipe.

4. The transfer pipe according to claim 1 , wherein the first guide portion is configured to have a first cycle in the first section of the guide portion in which the fluid is maintained as a liquid phase and the second guide portion is configured to have a second cycle in the second section of the guide portion in which the fluid is maintained as a liquid phase and a gas phase, and

wherein the guide portion further comprises a third guide portion extending toward the outlet from the second section, wherein the third guide portion is configured to have a third cycle in a third section of the guide portion in which the fluid is maintained as a gas phase.

5. The transfer pipe according to claim 4 , wherein a length of the second guide portion is relatively shorter than a length of the first guide portion.

6. The transfer pipe according to claim 4 , wherein:

the angle of extension of the entirety of the second guide portion with respect to the center vertical axis is relatively greater than the angle of extension of the entirety of the first guide portion with respect to the center vertical axis.

7. The transfer pipe according to claim 4 , wherein the branch passage is formed across the first and second sections.

8. The transfer pipe according to claim 4 , wherein the branch passage is formed in only the second section.

9. The transfer pipe according to claim 1 , wherein the angle of extension of the first guide portion is uniform throughout the first guide portion, and

wherein the angle of extension of the second guide portion is uniform throughout the second guide portion.

10. A transfer pipe for a furnace, comprising:

a body portion having an inlet and an outlet through which a fluid is transferred;

a guide portion formed on an inner wall of the body portion and extending in a spiral form in a longitudinal direction of the body portion, so that the body portion has a polygonal cross-sectional shape;

wherein the polygonal cross-sectional shape includes polygonal sides and a junction of adjacent ones of the polygonal sides is rounded; and

diameter change portions that repeatedly protrude in a longitudinal direction of the transfer pipe that are disposed on each of the polygonal sides,

wherein the guide portion has an inner peripheral surface which has an N-sided polygonal cross-section in a first section and an (N−1)-sided polygonal cross-section in a second section, wherein N is a positive integer,

wherein the guide portion comprises a first guide portion extending in the longitudinal direction of the body portion from the inlet and a second guide portion extending upward from the first guide portion, and

wherein an angle of extension of an entirety of the first guide portion with respect to a center vertical axis is different from an angle of extension of an entirety of the second guide portion with respect to the center vertical axis.

11. The transfer pipe according to claim 10 , wherein the diameter change portions protrude from the inner wall of the body portion in a rounded form in the longitudinal direction of the transfer pipe.

12. The transfer pipe according to claim 10 , wherein the first guide portion is configured to have a first cycle in the first section of the guide portion in which the fluid is maintained as a liquid phase and the second guide portion is configured to have a second cycle in the second section of the guide portion in which the fluid is maintained as a liquid phase and a gas phase, and

wherein the guide portion further comprises a third guide portion extending toward the outlet from the second section, wherein the third guide portion is configured to have a third cycle in a third section of the guide portion in which the fluid is maintained as a gas phase.

13. The transfer pipe according to claim 12 , wherein a length of the second guide portion is relatively shorter than a length of the first guide portion.

14. The transfer pipe according to claim 12 , wherein the guide portion comprises a branch passage formed on the inner wall of the body portion, wherein the branch passage is inclined with respect to the polygonal sides, so as to intersect with the adjacent ones of the polygonal sides.

15. The transfer pipe according to claim 14 , wherein the branch passage is formed across the first and second sections.

16. The transfer pipe according to claim 14 , wherein the branch passage is formed in only the second section.

17. The transfer pipe according to claim 10 , wherein the angle of extension of the first guide portion is uniform throughout the first guide portion, and

wherein the angle of extension of the second guide portion is uniform throughout the second guide portion.

18. A transfer pipe for a furnace, comprising:

a body portion having an inlet and an outlet through which a fluid is transferred, wherein an outer diameter of the body portion is uniform;

a guide portion having polygonal sides formed on an inner wall of the body portion and extending in a spiral form in a longitudinal direction of the body portion; and

diameter change portions that repeatedly protrude in a longitudinal direction of the transfer pipe from the inner wall of the body portion in a rounded form,

wherein the guide portion has an inner peripheral surface which has an N-sided polygonal cross-section in a first section and an (N−1)-sided polygonal cross-section in a second section, wherein N is a positive integer,

wherein the guide portion comprises a first guide portion extending in the longitudinal direction of the body portion from the inlet and a second guide portion extending upward from the first guide portion, and

wherein an angle of extension of the first guide portion with respect to a center vertical axis is different from an angle of extension of the second guide portion with respect to the center vertical axis.

19. The transfer pipe according to claim 18 , wherein the angle of extension of the first guide portion is uniform throughout the first guide portion, and

wherein the angle of extension of the second guide portion is uniform throughout the second guide portion.