Gas-fired steam boiler with gap structure

Patent metadata

Field	Value
Publication number	US-12117208-B2
Application number	US-202217869967-A
Country	US
Kind code	B2
Filing date	Jul 21, 2022
Priority date	Mar 29, 2021
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

A gas-fired steam boiler, including multiple heat exchange tubes, an upper steam header, a lower steam header, a casing, a burner, a condenser, a chimney, and a controller. The heat exchange tubes are vertically arranged to form an annular tube row. A space enclosed by the annular tube row is configured as a furnace. Adjacent two heat exchange tubes are combined to form a gap channel evenly distributed along a circumferential direction. A width of the gap channel is 0.1-4 mm, and a circumferential length of the gap channel is 50-300 mm. A length of the gap channel along an axial direction of the heat exchange tube is the same as a length of the heat exchange tube.

First claim

What is claimed is:

1. A gas-fired steam boiler, comprising:
a plurality of heat exchange tubes;
an upper steam header;
a lower header;
a casing;
a burner;
a condenser; and
a chimney;
wherein the gas-fired steam boiler is vertically arranged; the plurality of heat exchange tubes are vertically arranged to form an annular tube row; a space enclosed by the annular tube row is configured as a furnace; a gap channel is provided between adjacent two of the plurality of heat exchange tubes, and is evenly distributed along a circumferential direction; an upper end of each of the plurality of heat exchange tubes extends into the upper steam header, and a lower end of each of the plurality of heat exchange tubes extends into the lower header; the upper steam header and the lower header are both annular; a section of the upper steam header coplanar with an axis of the gas-fired steam boiler is rectangular, circular, or triangular; a section of the lower header coplanar with the axis of the gas-fired steam boiler is rectangular, circular, or triangular; the upper steam header is provided with a steam outlet, a safety valve, a first water level gauge interface, a pressure gauge or pressure sensor interface, and a burner mounting panel; the lower header is provided with a first water inlet, a waste water outlet, a separator for separating the furnace from the condenser, and a second water level gauge interface; a top of the casing is connected to an outer edge of a bottom of the upper steam header; the casing is configured to surround the plurality of heat exchange tubes, the lower header and the condenser; a first annular space is provided between the casing and the plurality of heat exchange tubes, and a second annular space is provided between the casing and the lower header; the first annular space and the second annular space are configured for flow of flue gas; the burner is fixedly arranged on the burner mounting panel; the condenser is arranged below or at an outer side of the lower header, and is configured to condense the flue gas flowing from the second annular space; a bottom of the casing is provided with a condensate collecting plate; and the condensate collecting plate is located below the condenser; the chimney is located at an end of the condensate collecting plate, and is separated from an outer edge of the upper steam header;
the plurality of heat exchange tubes are finned circular tubes;
the condenser is a coil condenser, a combined gap-type condenser, or a gap-type coil condenser;
the burner is a diffusion burner or a full premix burner;
natural gas and air are mixed uniformly in an inlet end of the burner and then enter the furnace from up to bottom to undergo combustion; the flue gas generated by the combustion enters the gap channel under a co-constraint of the burner mounting panel and the separator; after being cooled in the gap channel, the flue gas passes through the first annular space and the second annular space in sequence to enter the condenser for cooling and condensation; the flue gas flowing out of the condenser enters the condensate collecting plate to allow condensed water to be collected and then flows upward to leave the gas-fired steam boiler through the chimney; boiler feed water enters the condenser to absorb residual heat of the flue gas, and then passes through the first water inlet to enter the lower header to be evenly distributed to the finned circular tubes; the boiler feed water absorbs heat and vaporizes into steam while flowing upward along the finned circular tubes; and the steam flows upward to the upper steam header to leave the gas-fired steam boiler from the steam outlet; and
each of the finned circular tubes comprises a base tube and an arc-shaped fin; an inner diameter of the arc-shaped fin is greater than an outer diameter of the base tube; the gap channel is formed between the arc-shaped fin of one of adjacent two finned circular tubes and the base tube of the other of the adjacent two finned circular tubes, and a width of the gap channel is 0.1-4 mm; the arc-shaped fin is configured to fully, half, unilaterally or bilaterally enclose the base tube of an adjacent finned circular tube; for each of the finned circular tubes, an outer circumference of the base tube intersects with, is tangent to, or is separated from a circle where an outer circumference of the arc-shaped fin is located; when the outer circumference of the base tube is separated from the circle where the outer circumference of the arc-shaped fin is located, a spacing therebetween is set to be less than 5 mm to ensure that there is enough fusion area between the based tube and the arc-shaped fin; for adjacent two finned circular tubes, an outer circumference of the base tube; a circle where an inner circumference of the arc-shaped fin of one finned circular tube is located is separated from an outer circumference of the base tube of the other finned circular tube to form the gap channel; the base tube is made of a material specified in a gas boiler standard, and the arc-shaped fin is made of a material with a high thermal conductivity; an inner side of the arc-shaped fin is provided with triangular corrugation, sinusoidal corrugation, arc-tangent corrugation, or rectangular corrugation to expand a heat exchange area of the arc-shaped fin, disturb the flue gas, and enhance a heat exchanging effect; a first positioning sheet is spot-welded on a surface of the base tube, and a thickness of the first positioning sheet is equal to the width of the gap channel; an inner surface of the arc-shaped fin abuts against the first positioning sheet on the base tube of an adjacent finned circular tube to allow the width of the gap channel to reach a preset value; two ends of the base tube are respectively welded with a necking connector or necked down to form a necking connector to enable welding when a distance between adjacent two finned circular tubes is too small to be welded; and the necking connector is not connected to the arc-shaped fin.

2. The gas-fired steam boiler of claim 1 , wherein the adjacent two finned circular tubes are arranged concentrically or eccentrically; when the adjacent two finned circular tubes are arranged concentrically, a central axis of the base tube of one of the adjacent two finned circular tubes coincides with a central axis of the arc-shaped fin of the other of the adjacent two finned circular tubes, and an angle formed by connecting lines between central axes of base tubes of sequentially-distributed three finned circular tubes is calculated by: 180°−(360°/n), wherein n represents the number of the finned circular tubes arranged along a circumferential direction; when the adjacent two finned circular tubes are arranged eccentrically, an angle formed by connecting lines between central axes of base tubes of the sequentially-distributed three finned circular tubes is calculated by: 180°−(360°/n), wherein n represents the number of the finned circular tubes arranged along the circumferential direction; when the central axis of the base tube of one of the adjacent two finned circular tubes is not coincided with the central axis of the arc-shaped fin of the other of the adjacent two finned circular tubes, each of the finned circular tubes rotates towards the furnace by a preset angle around the central axis of the base tube such that an inlet of the gap channel is larger than an outlet of the gap channel to adapt to volume change of the flue gas during cooling; the finned circular tubes are uniformly arranged along the circumferential direction to form the annular tube row; and when a power of the gas-fired steam boiler is increased, two, three or four annular tube rows are arranged to enlarge the heat exchange area.

3. The gas-fired steam boiler of claim 1 , wherein when the base tube and the arc-shaped fin are both made of steel, the base

Assignees

• Univ Xi An Jiaotong

Inventors

• Deng Shifeng
• Zhao Qinxin
• Shao Huaishuang
• Wang Yungang
• Liang Zhiyuan

Classifications

• F24H9/0026 Primary

  in combustion gas channels · CPC title

• F24H1/43

  helically or spirally coiled · CPC title

• F24H8/006 Primary

  Means for removing condensate from the heater · CPC title

• Y02B30/00

  Energy efficient heating, ventilation or air conditioning [HVAC] · CPC title

• F28B9/08

  for collecting and removing condensate · CPC title