Heat transfer tube, boiler and steam turbine device

A heat transfer tube which is provided in a boiler, an interior of the heat transfer tube having a supercritical pressure and a heating medium flowing through the interior, the heat transfer tube comprising:

• a groove portion that is formed on an inner circumferential surface and has a spiral shape toward a tube axis direction;
• and
• a rib portion that is formed to protrude inward in a radial direction by the groove portion of the spiral shape,
• wherein, when a height [mm] of the rib portion in the radial direction is defined as Hr, an interval [mm] of the rib portion in the tube axis direction is defined as Pr, the number of the rib portion in the cross section which is taken perpendicularly to the tube axis direction is defined as Nr, and a wetted perimeter length [mm] of the cross section which is taken perpendicularly to the tube axis direction is defined as L,
• the height Hr [mm] of the rib portion, the interval Pr [mm] of the rib portion, the number Nr of the rib portion (37) and the wetted perimeter length L [mm] satisfy “(Pr·Nr)/Hr>1.25 L+55”.

A heat transfer tube which is provided in a boiler, an interior of the heat transfer tube having a supercritical pressure and a heating medium flowing through the interior, the heat transfer tube comprising:

• a groove portion that is formed on an inner circumferential surface and has a spiral shape toward a tube axis direction;
• and
• a rib portion that is formed to protrude inward in a radial direction by the groove portion of the spiral shape,
• wherein, when a height [mm] of the rib portion in the radial direction is defined as Hr, an interval [mm] of the rib portion in the tube axis direction is defined as Pr, a width [mm] of the rib portion in a circumferential direction of the inner circumferential surface is defined as Wr, the number of the rib portion in the cross section which is taken perpendicularly to the tube axis direction is defined as Nr, a wetted perimeter length [mm] of the cross section which is taken perpendicularly to the tube axis direction is defined as L, a width [mm] of the groove portion in the tube axis direction of the cross section which is taken along the tube axis direction is defined as Wg, and a tube outer diameter [mm] is defined as D,
• the width Wg [mm] of the groove portion, the height Hr [mm] of the rib portion, and the tube outer diameter D [mm] satisfy “Wg/(Hr·D)>0.40”, and
• the height Hr [mm] of the rib portion, the interval Pr [mm] of the rib portion, the width Wr [mm] of the rib portion, the number Nr of the rib portion and the wetted perimeter length L [mm] satisfy “(Pr·Nr)/(Hr·Wr)>0.40 L+9.0”.