A segmented watertube boiler system allows for rapidly expanding the capacity of a boiler. The system joins boiler segments to form a boiler. The segments have portions of the boiler so that the storage capacity for water and heat are increased with the number of segments uses. Any openings in the segments on the ends are capped off and heat and water sources are attached. The boiler can be cleaned and maintained by simply disassembling the segments to provide access to the whole boiler.

Disclosed herein is a transfer pipe for a furnace. The transfer pipe for a furnace includes a body portion having an inlet and an outlet through which a fluid is transferred, a guide portion having polygonal sides extending in a spiral form in an inward longitudinal direction of the body portion, and a diameter change portion repeatedly changing an inner diameter of the body portion in the longitudinal direction thereof.

Disclosed herein is a transfer pipe for a furnace. The transfer pipe for a furnace includes a body portion having an inlet and an outlet through which a fluid is transferred, a guide portion having polygonal sides extending in a spiral form in an inward longitudinal direction of the body portion, and a diameter change portion repeatedly changing an inner diameter of the body portion in the longitudinal direction thereof.

Transition castings are disclosed which comprise a steam tube and a water tube, which are joined together by membranes. A heat transfer fin extends from the membrane and abuts the water tube. The steam tube bends such that an upper end is on one side of the water tube, and a lower end is on an opposite side of the water tube. The transition castings are used in a transition section of a boiler in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. The transition casting joins the lower furnace and the upper furnace together.

Transition castings are disclosed which comprise a steam tube and a water tube, which are joined together by membranes. A heat transfer fin extends from the membrane and abuts the water tube. The steam tube bends such that an upper end is on one side of the water tube, and a lower end is on an opposite side of the water tube. The transition castings are used in a transition section of a boiler in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. The transition casting joins the lower furnace and the upper furnace together.

A heat exchanger unit includes tube units arranged within a duct unit for heat exchange with combustion gas supplied from a furnace of a thermal power plant, and heat exchanger fins longitudinally formed on outer peripheral surfaces of the tube units and having different thickness and sizes while heat exchange with the combustion gas is performed through the heat exchanger fin.

A heat exchanger unit includes tube units arranged within a duct unit for heat exchange with combustion gas supplied from a furnace of a thermal power plant, and heat exchanger fins longitudinally formed on outer peripheral surfaces of the tube units and having different thickness and sizes while heat exchange with the combustion gas is performed through the heat exchanger fin.

A heat transfer tube for a boiler, an interior of the heat transfer tube having a supercritical pressure and being configured to have a heating medium flow therethrough, includes: a groove portion defined on an inner circumferential surface and having a spiral shape extending continuously toward a tube axis direction; and a rib portion extending continuously and protruding inward in a radial direction by the groove portion of the spiral shape. In a cross section taken along the tube axis direction, a width of the groove portion in the tube axis direction is defined as Wg, a height of the rib portion in the radial direction is defined as Hr and a tube outer diameter is defined as D, and the width Wg of the groove portion, the height Hr of the rib portion, and the tube outer diameter D satisfy Wg/(Hr.Math.D)>0.40.

A heat transfer tube for a boiler, an interior of the heat transfer tube having a supercritical pressure and being configured to have a heating medium flow therethrough, includes: a groove portion defined on an inner circumferential surface and having a spiral shape extending continuously toward a tube axis direction; and a rib portion extending continuously and protruding inward in a radial direction by the groove portion of the spiral shape. In a cross section taken along the tube axis direction, a width of the groove portion in the tube axis direction is defined as Wg, a height of the rib portion in the radial direction is defined as Hr and a tube outer diameter is defined as D, and the width Wg of the groove portion, the height Hr of the rib portion, and the tube outer diameter D satisfy Wg/(Hr.Math.D)>0.40.

A method for producing a heat transfer tube for a steam generator comprises a step of providing a tube and then applying cold drawing to the tube by using a high-pressure lubricating oil of 40 MPa or more in pressure. After the step of applying cold drawing to the tube, a step of applying a solid solution heat treatment to the tube is conducted. After the step of applying a solid solution heat treatment to the tube, a step of straightening the tube by using a roll straightening machine is conducted. An offset amount of 5 mm or less is formed for at least successive three pairs of upper and lower straightening rolls of the roll straightening machine.