Horizontal three-return-stroke membrane wall hot water boiler

Abstract

The utility model discloses a horizontal type three-return-stroke membrane type wall hot water boiler which comprises a shell, the interior of the shell is sequentially divided into a water cavity, a hearth and a steam space from bottom to top, the position, corresponding to the water cavity and the hearth, of the front end of the shell shrinks backwards, the front end of the hearth is connected with a burner, and the rear end of the hearth is connected with a vertical condenser. The hearth is divided into three heat exchange areas by membrane wall heat exchange pipes from front to back, high-temperature smoke flows along the three heat exchange areas in an S shape, a fixed tube-sheet heat exchanger is horizontally arranged in the steam space, and a heat exchanger water inlet is formed in the bottom of a rear tube box of the fixed tube-sheet heat exchanger. A top water outlet of the vertical condenser is connected with a water inlet of the heat exchanger; and a smoke outlet at the rear end of the vertical condenser is connected with the chimney. The horizontal three-return-stroke membrane wall hot water boiler has the advantages of being more compact in structure, lower in manufacturing, transporting and using cost, higher in boiler heat efficiency and the like.

Description

Technical Field

[0001] The utility model relates to a hot water boiler, in particular to a horizontal three-pass membrane wall hot water boiler. Background Art

[0002] The thermal efficiency of a boiler refers to the percentage of heat effectively utilized by the boiler per unit time to the heat input by the boiler. Most of the heat sent into the boiler by the fuel is absorbed by the heating surface of the boiler, which is the effective heat that is utilized, while the other part of the heat is lost. This part of heat is called heat loss. Improving the thermal efficiency of the boiler means reducing the various heat losses of the boiler.

[0003] Since part of the heat loss of the furnace body depends on the external insulation. In order to reduce this part of the heat loss, membrane wall boilers came into being. Chinese patent CN202121029983.3 discloses a membrane wall hot water boiler, which greatly improves the boiler's heat transfer efficiency by adopting a furnace with a membrane wall structure and an S-shaped convection flue three-return structure. However, the boiler structure of this patent still has some areas that need improvement, such as the protruding front burner, which occupies a large space; the exhaust temperature of the boiler is relatively high, between 90°C and 110°C; the thermal efficiency of the main body design still has room for further improvement. Utility Model Content

[0004] The purpose of the utility model is to provide a horizontal three-pass membrane wall hot water boiler to solve the problems existing in the prior art.

[0005] The purpose of the utility model is achieved as follows: a horizontal three-pass membrane wall hot water boiler, comprising a shell, the shell is divided into a water chamber, a furnace and a steam space from bottom to top, the front end of the shell is contracted backward corresponding to the position of the water chamber and the furnace, the front end of the furnace is connected to the burner, and the rear end is connected to the vertical condenser, the furnace is divided into three heat exchange zones from front to back by membrane wall heat exchange tubes, the high-temperature flue gas flows in an S-shape along the three heat exchange zones, a fixed tube plate heat exchanger is horizontally arranged in the steam space, a heat exchanger water inlet is provided at the bottom of the rear tube box of the fixed tube plate heat exchanger, the vertical condenser is arranged directly below the rear tube box and the top water outlet is connected to the heat exchanger water inlet, and the rear end smoke outlet of the vertical condenser is connected to the chimney.

[0006] The horizontal three-pass membrane wall hot water boiler of this utility model has a setback design at the front end of the furnace, which reserves space for the installation of the burner. By arranging a vertical condenser at the rear end of the furnace, the furnace thermal efficiency is further improved and the exhaust gas temperature is reduced. Moreover, since the vertical condenser is located directly below the rear tube box of the fixed tube plate heat exchanger, the overall structure is compact, saving space, simplifying the connection of the water circulation pipeline, and saving costs. In summary, the horizontal three-pass membrane wall hot water boiler of this utility model has the advantages of a more compact structure, lower manufacturing, transportation and use costs, and higher boiler thermal efficiency.

[0007] As a further improvement to the present invention, the burner utilizes a flat, water-cooled design. Heat exchange tubes are installed within the heat exchange zone, with the smallest number of tubes located in the frontmost heat exchange zone. This flat, water-cooled burner features a short flame and relatively low combustion temperature. This helps shorten the frontmost heat exchange zone, reduces the number of heat exchange tubes, and ensures that exhaust gas temperatures remain within control, even with a setback design at the front end of the furnace.

[0008] As a further improvement to the present invention, the heat exchange tubes in the rearmost heat exchange zone are finned, while the heat exchange tubes in the remaining heat exchange zones are bare tubes. Bare tubes in the first two heat exchange zones simplify fabrication, increase the speed at which high-temperature flue gas passes through, and extend the tube's service life. Finned tubes in the final heat exchange zone extend heat exchange time, fully absorb waste heat, reduce boiler exhaust temperature, and improve boiler thermal efficiency.

[0009] As a further improvement of the present invention, steam baffles are symmetrically arranged in the steam space. The upper end of the steam baffle is welded and fixed to the shell, and the lower end is inclined and extended to a position close to the heat exchange tube bundle of the fixed tube plate heat exchanger to guide the steam to flow to the heat exchange tube bundle and improve the heat exchange effect.

[0010] As a further improvement of the present invention, the upper portion of the steam space is semicircular, which improves the pressure bearing capacity, enhances the safety performance of the equipment, increases the steam space, and improves the steam quality.

[0011] As a further improvement of the present invention, a vacuum pressure gauge, a safety valve, a temperature sensor, a liquid level sensor and a vacuum sight glass are provided on the upper part of the steam space to ensure safe and reliable operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of a horizontal three-pass membrane wall hot water boiler of the present invention.

[0013] Figure 2 Figure 1 Transverse cross-sectional view of the center furnace.

[0014] Figure 3 for Figure 1 side view.

[0015] Among them, 1 shell, 2 water chamber, 3 furnace, 4 steam space, 5 burner, 6 vertical condenser, 7 membrane wall heat exchange tube, 8 smooth tube heat exchange tube, 9 finned heat exchange tube, 10 fixed tube plate heat exchanger, 10A rear tube box, 11 vacuum pressure gauge, 12 safety valve, 13 temperature sensor, 14 liquid level sensor, 15 vacuum sight glass, 16 steam baffle. DETAILED DESCRIPTION

[0016] like Figure 1-3 The horizontal three-pass membrane wall hot water boiler shown comprises a shell 1 , which is divided into a water chamber 2 , a furnace 3 and a steam space 4 from bottom to top.

[0017] The front end of the shell 1 is retracted backwards corresponding to the position of the water chamber 2 and the furnace 3. The front end of the furnace 3 is connected to the burner 5, and the rear end smoke outlet is connected to the vertical condenser 6. A fixed tube plate heat exchanger 10 is horizontally arranged in the steam space 4. The bottom of the rear tube box 10A of the fixed tube plate heat exchanger 10 is provided with a heat exchanger water inlet. The vertical condenser 6 is arranged directly below the rear tube box 10A and the top water outlet is connected to the heat exchanger water inlet. The rear end smoke outlet of the vertical condenser 6 is connected to the chimney. The retracted design of the front end of the furnace 3 reserves space for the installation of the burner 5, and by arranging the vertical condenser 6 at the rear end of the furnace 3, the furnace thermal efficiency is further improved and the exhaust gas temperature is reduced. Since the vertical condenser 6 is arranged directly below the rear tube box 10A of the fixed tube plate heat exchanger 10, the overall structure is compact, space is saved, and the connection of the water circulation pipeline is simplified, saving costs.

[0018] The furnace 3 is divided into three heat exchange zones from front to back by the membrane wall heat exchange tubes 7, and the high-temperature flue gas flows in an S-shape along the three heat exchange zones. Heat exchange tubes are provided in the heat exchange zones. The heat exchange tubes in the heat exchange zone at the rear end are finned heat exchange tubes 9, and the heat exchange tubes in the other heat exchange zones are bare tube heat exchange tubes 8. The lower ends of the membrane wall heat exchange tubes 7, bare tube heat exchange tubes 8, and finned heat exchange tubes 9 are connected to the water cavity 2, and the upper ends are connected to the steam space 4. The heat exchange tubes in the first two heat exchange zones are bare tube heat exchange tubes 8, which are simple to process, help increase the speed of high-temperature flue gas passing through, and extend the service life of the heat exchange tubes. The heat exchange tubes in the last heat exchange zone are finned heat exchange tubes 9, which extend the heat exchange time, fully absorb waste heat, reduce the boiler exhaust temperature, and improve the boiler thermal efficiency.

[0019] In this embodiment, the burner 5 is a flat water-cooled burner 5. The flat water-cooled burner 5 has the characteristics of short combustion flame and relatively low combustion temperature, which helps to shorten the length of the front end heat exchange zone and reduce the number of heat exchange tubes in the front end heat exchange zone, ensuring that the exhaust gas temperature is within the control range when the front end of the furnace 3 adopts a retracted design. Figure 2 As shown, the number of heat exchange tubes in the front heat exchange zone is greatly reduced compared with the number of heat exchange tubes in the two rear heat exchange zones.

[0020] like Figure 1 、 Figure 3As shown, the upper portion of the steam space 4 is semicircular, increasing pressure bearing capacity and enhancing equipment safety. The larger steam space 4 also improves steam quality. A vacuum pressure gauge 11, safety valve 12, temperature sensor 13, liquid level sensor 14, and vacuum sight glass 15 are located above the steam space 4, effectively ensuring safe and reliable equipment operation. Steam baffles 16 are symmetrically positioned within the steam space 4. The upper ends of these baffles are welded to the shell 1, while the lower ends extend at an angle close to the heat exchange tube bundle of the tube-sheet heat exchanger 10. This guides steam flow toward the heat exchange tube bundle, enhancing heat exchange efficiency.

[0021] The horizontal three-pass membrane wall hot water boiler of this embodiment has the following flow of flue gas and medium:

[0022] Flue gas flow: fuel → burner 5 → furnace 2 → vertical condenser 6 → chimney;

[0023] Steam-water system: softened feed water → water tank → circulating pump → vertical condenser 6 → fixed tube-sheet heat exchanger 10 → water distribution tank → heat user.

[0024] The horizontal three-pass membrane-wall hot water boiler in this embodiment utilizes membrane-wall water tube design technology to ensure the overall sealing of the boiler flue, reduce the thickness of the insulation layer, and significantly lower the outer surface temperature. The use of finned water tubes for heat exchange exponentially increases the convective heating surface within a relatively small flue space. The high-temperature flue gas in the furnace passes through the furnace outlet smokestack (front middle membrane wall) and then laterally scours the second convection tube bundle in the second pass for heat exchange. It then passes through the second convection tube bundle outlet smokestack (rear middle membrane wall) and then further heat exchanges through the third pass second convection tube bundle. It then passes through the tail flue gas outlet and the vertical condenser for further heat exchange before being discharged into the chimney. Ultimately, the boiler's exhaust temperature is reduced to below 65°C, achieving a design thermal efficiency of up to 102%. Throughout boiler operation, the flat water-cooled microporous ultra-low nitrogen burner automatically adjusts the air-fuel ratio based on the oxygen content in the flue gas, timely controlling ultra-low nitrogen emissions from the boiler flue gas, ultimately achieving low nitrogen emissions and high efficiency and energy conservation.

[0025] In summary, the horizontal three-pass membrane wall hot water boiler of this embodiment has the advantages of more compact structure, lower manufacturing, transportation and use costs, and higher boiler thermal efficiency.

[0026] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, technicians in this field can make some substitutions and deformations of some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A horizontal three-pass membrane wall hot water boiler, comprising a shell, wherein the shell is divided into a water chamber, a furnace and a steam space from bottom to top, characterized in that: The front end of the shell shrinks backward corresponding to the position of the water cavity and the furnace. The front end of the furnace is connected to the burner and the rear end is connected to the vertical condenser. The furnace is divided into three heat exchange zones from front to back by membrane wall heat exchange tubes. The high-temperature flue gas flows in an S shape along the three heat exchange zones. A fixed tube plate heat exchanger is horizontally arranged in the steam space. A heat exchanger water inlet is provided at the bottom of the rear tube box of the fixed tube plate heat exchanger. The vertical condenser is arranged directly below the rear tube box and the top water outlet is connected to the heat exchanger water inlet. The rear end smoke outlet of the vertical condenser is connected to the chimney.

2. The horizontal three-pass membrane wall hot water boiler according to claim 1, characterized in that: The burner is a flat water-cooled burner. Heat exchange tubes are arranged in the heat exchange area, and the number of heat exchange tubes located in the front end heat exchange area is the least.

3. The horizontal three-pass membrane wall hot water boiler according to claim 2, characterized in that: The heat exchange tubes in the rear end heat exchange zone are finned heat exchange tubes, and the heat exchange tubes in other heat exchange zones are plain tube heat exchange tubes.

4. The horizontal three-pass membrane wall hot water boiler according to claim 1, characterized in that: Steam baffles are symmetrically arranged in the steam space. The upper ends of the steam baffles are welded and fixed to the shell, and the lower ends are inclined and extended to a position close to the heat exchange tube bundle of the fixed tube plate heat exchanger.

5. The horizontal three-pass membrane wall hot water boiler according to any one of claims 1 to 4, characterized in that: The upper portion of the steam space is semicircular.

6. The horizontal three-pass membrane wall hot water boiler according to any one of claims 1 to 4, characterized in that: A vacuum pressure gauge, a safety valve, a temperature sensor, a liquid level sensor and a vacuum sight glass are provided on the upper part of the steam space.

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