Transition castings are disclosed which comprise a steam tube, a water tube, and a pass-through tube, which are joined together by membranes. The ends of the tubes on one vertical end are aligned in a plane, while the ends of the tubes on the other vertical end are aligned in alternating planes, or put another way are angled instead of being in a straight line. 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 section joins the lower furnace and the upper furnace together.

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct including vertical flue gas channels, at least some of which are provided with heat recovery units for recovering heat from flue gases. The first flue gas channel downstream of the furnace is provided with a reheater and one of the following heat recovery units: an economizer or a boiler bank. The reheater and the second heat recovery unit are located one after the other in the horizontal incoming direction of the flue gas, so that in a flue gas channel the flue gas flows in a vertical direction from above downwards and heats the reheater and the second heat recovery unit simultaneously. The heat recovery elements of the reheater and the second heat recovery unit may be positioned side by side in a direction that is crosswise with respect to the horizontal incoming direction of the flue gas.

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct including vertical flue gas channels, at least some of which are provided with heat recovery units for recovering heat from flue gases. The first flue gas channel downstream of the furnace is provided with a reheater and one of the following heat recovery units: an economizer or a boiler bank. The reheater and the second heat recovery unit are located one after the other in the horizontal incoming direction of the flue gas, so that in a flue gas channel the flue gas flows in a vertical direction from above downwards and heats the reheater and the second heat recovery unit simultaneously. The heat recovery elements of the reheater and the second heat recovery unit may be positioned side by side in a direction that is crosswise with respect to the horizontal incoming direction of the flue gas.

A modification of a power boiler is disclosed, which comprises water walls enclosing the furnace for heating water and producing steam; a superheater system provided above the furnace for superheating steam; an additional superheater mounted in the furnace for further superheating steam from the superheater system. A modifying method of a power boiler is also disclosed, which comprises steps of mounting an additional superheater on water walls in a furnace; connecting an output of a superheater system to an inlet of the additional superheater; and connecting an outlet of the additional superheater to a turbine for producing power at an improved plant heat rate.

A modification of a power boiler is disclosed, which comprises water walls enclosing the furnace for heating water and producing steam; a superheater system provided above the furnace for superheating steam; an additional superheater mounted in the furnace for further superheating steam from the superheater system. A modifying method of a power boiler is also disclosed, which comprises steps of mounting an additional superheater on water walls in a furnace; connecting an output of a superheater system to an inlet of the additional superheater; and connecting an outlet of the additional superheater to a turbine for producing power at an improved plant heat rate.

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct comprising vertical flue gas channels, at least part of which is provided with heat recovery units for recovering heat from flue gases. The heat recovery units have a width of substantially the width of the flue gas duct, whereby downstream of the furnace the first flue gas channel is provided with a superheater. In addition to the superheater, the first flue gas channel is provided with one of following heat recovery units: an economizer, a boiler bank, or a reheater. The superheater and a second heat recovery unit are located one after the other in horizontal introduction direction of the flue gas, so that in a flue gas channel the flue gas flows in the vertical direction downwards and heats the superheater and the second heat recovery unit simultaneously

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct comprising vertical flue gas channels, at least part of which is provided with heat recovery units for recovering heat from flue gases. The heat recovery units have a width of substantially the width of the flue gas duct, whereby downstream of the furnace the first flue gas channel is provided with a superheater. In addition to the superheater, the first flue gas channel is provided with one of following heat recovery units: an economizer, a boiler bank, or a reheater. The superheater and a second heat recovery unit are located one after the other in horizontal introduction direction of the flue gas, so that in a flue gas channel the flue gas flows in the vertical direction downwards and heats the superheater and the second heat recovery unit simultaneously

A chemical recovery boiler (100), including a furnace (1), comprising a front wall (2), a back wall (3), and the back wall (3) comprising a nose arch (4). The boiler further comprises at least one superheater (5) arranged in upper part of the furnace (1), and a screen pipe system (6), comprising an obliquely arranged screen pipe section (7) positioned before/under the at least one superheater (5) in the furnace (1). The obliquely arranged screen pipe section (7) comprises screen pipes (8) ascending (i) either from the front wall (2) to the back wall (3), and arranged to turn back in a turn (13) from the back wall (3) and extend obliquely upwards from the back wall (3), or (ii) from the back wall (3) to the front wall (2), and arranged to turn back in a turn (13) from the front wall (2) and extend obliquely upwards from the front wall (2). The screen pipe system (6) further comprises a vertically arranged screen pipe section (9) extending from the obliquely arranged screen pipe section (7). The screen pipes (8) of the vertically arranged screen pipe section (9) are arranged to extend parallel with the at least one superheater (5) in upper part of the furnace (1).

A chemical recovery boiler (100), including a furnace (1), comprising a front wall (2), a back wall (3), and the back wall (3) comprising a nose arch (4). The boiler further comprises at least one superheater (5) arranged in upper part of the furnace (1), and a screen pipe system (6), comprising an obliquely arranged screen pipe section (7) positioned before/under the at least one superheater (5) in the furnace (1). The obliquely arranged screen pipe section (7) comprises screen pipes (8) ascending (i) either from the front wall (2) to the back wall (3), and arranged to turn back in a turn (13) from the back wall (3) and extend obliquely upwards from the back wall (3), or (ii) from the back wall (3) to the front wall (2), and arranged to turn back in a turn (13) from the front wall (2) and extend obliquely upwards from the front wall (2). The screen pipe system (6) further comprises a vertically arranged screen pipe section (9) extending from the obliquely arranged screen pipe section (7). The screen pipes (8) of the vertically arranged screen pipe section (9) are arranged to extend parallel with the at least one superheater (5) in upper part of the furnace (1).

Liquid is flash evaporated in a series of cells along and surrounding an exhaust duct to generate a pressurized vapor where at least one of the surfaces is in communication with the source of heat sufficient to maintain the surface at a temperature such that the liquid injected into the chamber is substantially instantly converted to a superheated vapor with no liquid pooling within the chamber. The liquid is introduced by controlled injectors operating at a required rate. Each of the cells is periodically discharged by a pressure controlled relief valve and the vapor from the cells combined to form a continuous stream feeding a turbine or other energy conversion device. The outer wall of the cell is offset so that it contacts the inner wall at one point around the periphery. Heat transfer ribs and bars can be provided in the duct to provide increased heat transfer where necessary.