A once-through coil boiler with a superheat section located in the furnace

Abstract

The present application is suitable for the technical field of direct-flow coil boiler, and provides a direct-flow coil boiler with a superheating section in a furnace, which comprises a boiler shell, a steam-water separator and a water injection temperature reducer; a burner connecting port is arranged at the lower end of the boiler shell; an exhaust port is arranged at the upper end of the boiler shell; a flat economizer coil, a coil water cooling wall spiral coil, a furnace water cooling wall spiral coil, a furnace water cooling wall low-temperature superheating section, a furnace water cooling wall high-temperature superheating section are sequentially arranged on the inner wall of the boiler shell from top to bottom; a flat evaporation section coil is arranged inside the coil water cooling wall spiral coil in the boiler shell; a water inlet is arranged on the outer wall of the upper end of the boiler shell and is communicated with the water inlet end of the flat economizer coil; the device arranges the superheating section on the water cooling wall, uses the radiant heat of the furnace to improve the superheat degree of the steam, realizes a larger steam superheat degree with a smaller area, reduces the use amount of the pipeline material, reduces the size of the boiler and reduces the weight of the boiler.

Description

Technical Field

[0001] This invention relates to the field of DC coil boiler technology, and more specifically, to a DC coil boiler with the superheating section located in the furnace. Background Technology

[0002] Currently, the superheater section of a typical once-through coil boiler uses a flat coil structure, arranged on the convective heating surface of the boiler, as shown in the attached figure. Figure 2 As shown, when the requirements for the superheating section of the boiler working fluid are large, the temperature difference between the flue gas and the working fluid is small, and a large convective heating area is required to achieve the target value of the outlet steam temperature.

[0003] For a boiler with a rated evaporation capacity of 45 t / h, an outlet working fluid pressure of 6.4 MPa, an outlet working fluid temperature of 480℃, and a superheat of 199℃, the superheated section pipes have large diameters and thick walls. If a flat coil structure is used on the convective heating surface, its structural characteristics will result in a large central void, significantly reducing the heating area of ​​each coil layer. Furthermore, the use of alloy steel pipes places high demands on the bending equipment, making manufacturing very difficult. Therefore, how to achieve a smaller boiler size with less heating area and how to reduce manufacturing difficulty are two major problems hindering existing technologies. To address this, this application provides a once-through coil boiler with the superheated section located in the furnace. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a direct-flow coil boiler with the superheating section located in the furnace. The superheating section is arranged on the water-cooled wall, and the radiant heat of the furnace is used to increase the superheat of the steam. A large steam superheat is achieved with a small area, which reduces the amount of pipe material used, reduces the size of the boiler, and reduces the weight of the boiler.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A once-through coil boiler with its superheating section located in the furnace includes a boiler shell, a steam-water separator, and a water spray desuperheater. A burner connection port is located at the lower end of the boiler shell. A flue gas outlet is located at the upper end of the boiler shell. From top to bottom, the inner wall of the boiler shell is provided with an economizer flat coil, a coil water-cooled wall spiral coil, a furnace water-cooled wall spiral coil, a furnace water-cooled wall low-temperature superheating section, and a furnace water-cooled wall high-temperature superheating section. An evaporation section flat coil is located inside the boiler shell, inside the coil water-cooled wall spiral coil. A feedwater inlet, communicating with the water inlet end of the economizer flat coil, is located on the outer wall of the upper end of the boiler shell.

[0007] The economizer flat coil, the water-cooled wall spiral coil, the evaporation section flat coil, the furnace water-cooled wall spiral coil, the steam-water separator, the furnace water-cooled wall low-temperature superheating section, the first water spray desuperheater, the furnace water-cooled wall high-temperature superheating section, and the second water spray desuperheater are connected in sequence.

[0008] The present invention is further configured such that the water flow direction of the spiral coil of the water-cooled wall is spiral upward from bottom to top; the economizer flat coil, the evaporation section flat coil, the furnace water-cooled wall spiral coil, the furnace water-cooled wall low-temperature superheating section, and the furnace water-cooled wall high-temperature superheating section are all conveyed from top to bottom.

[0009] The invention is further configured such that the water inlet is connected via a pipeline to a variable frequency plunger pump for boiler water supply. Boiler water, after being treated to meet boiler water quality requirements, is pressurized by the variable frequency plunger pump and then introduced into the water inlet.

[0010] The invention is further configured such that the economizer flat coil and the water-cooled spiral coil form a heating section. The economizer flat coil is the convective heating surface at the end of the boiler, with the working fluid and flue gas arranged in a counter-current manner, which can ensure a larger average temperature and pressure, absorb more heat, and improve boiler efficiency. This part of the flue gas has a low temperature, and the working fluid inside the tube is single-phase liquid water, preventing the tube wall temperature from becoming too high, and the counter-current arrangement ensures optimal performance. Boiler water, after being heated by the economizer flat coil, enters the water-cooled spiral coil. The structure of the water-cooled spiral coil serves to isolate the high-temperature flue gas from the boiler shell, and its relatively small heating area results in lower heat absorption.

[0011] The invention is further configured such that the flat coil of the evaporation section and the spiral coil of the furnace water-cooled wall constitute the evaporation section. Boiler water, after being heated by the spiral coil of the water-cooled wall, enters the flat coil of the evaporation section. The working fluid and flue gas are arranged in a counter-current flow. To accommodate the increased pipe diameter in subsequent evaporation sections, the specifications of this part of the flat coil gradually increase, making the flow velocity change within the pipe smoother. In the evaporation section, the boiler water partially transforms from saturated water to saturated steam, coexisting in both vapor and liquid phases.

[0012] After passing through the steam-water separator, the high-dryness saturated steam returns to the low-temperature superheating section of the furnace water-cooled wall, while the saturated water enters the deaerator tank via the condensate drainage system. Compared to the steam-water two-phase working fluid, the high-dryness steam causes less erosion and corrosion to the pipes in the low-temperature superheater section, thus offering higher safety.

[0013] Steam is heated in the low-temperature superheating section of the furnace water-cooled wall and then flows through the water spray desuperheater before entering the high-temperature superheating section of the furnace water-cooled wall. Since the low-temperature superheater and the high-temperature superheater are separate sections, the high-temperature superheater can be made of a high-temperature resistant material, and the influence of welding dissimilar steels does not need to be considered.

[0014] The present invention is further configured such that the pipe wall temperature of the high-temperature superheated section of the furnace water-cooled wall is relatively high, a wall temperature sensor is installed on the pipe of the high-temperature superheated section of the furnace water-cooled wall to detect the wall temperature, and a high-temperature alarm connected to the wall temperature sensor is installed on the outside of the boiler shell.

[0015] The invention is further configured such that a heat-resistant steel plate is installed between the inner wall of the boiler shell and the low-temperature superheated section and the high-temperature superheated section of the furnace water-cooled wall. This isolates some of the heat, thereby reducing the temperature of the boiler shell and lowering the requirements for the shell material.

[0016] The advantages of this invention are:

[0017] 1. The present invention arranges the superheating section in the furnace position, and uses the radiant heat of the furnace to increase the superheat of the steam, achieving a large steam superheat with a small area, which reduces the amount of pipe material used, reduces the size of the boiler, and reduces the weight of the boiler.

[0018] 2. The spiral water-cooled wall tubes in the furnace of this invention are much easier to manufacture than flat coil structures. This greatly reduces the difficulty in manufacturing, cost control, weight control, and boiler size, and reduces the requirements for installation space. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the DC coil boiler of the present invention, in which the superheating section is located in the furnace.

[0020] Figure 2 This is a schematic diagram of an existing DC coil boiler.

[0021] In the diagram: 1. Boiler shell; 2. Steam-water separator; 3. Water spray desuperheater; 4. Economizer flat coil; 5. Water-cooled wall spiral coil; 6. Evaporator section flat coil; 7. Furnace water-cooled wall spiral coil; 8. Furnace water-cooled wall low-temperature superheated section; 9. Furnace water-cooled wall high-temperature superheated section; 11. Burner connection port; 12. Flue gas outlet; 13. Feedwater inlet. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0025] Example 1

[0026] Please see Figure 1 The present invention provides the following technical solution for a once-through coil boiler with the superheating section located in the furnace:

[0027] Specifically, it includes a boiler shell 1, a steam-water separator 2, and a water spray desuperheater 3; a burner connection port 11 is provided at the lower end of the boiler shell 1; a flue gas outlet 12 is provided at the upper end of the boiler shell 1; from top to bottom, the inner wall of the boiler shell 1 is provided with an economizer flat coil 4, a coil water-cooled wall spiral coil 5, a furnace water-cooled wall spiral coil 7, a furnace water-cooled wall low-temperature superheating section 8, and a furnace water-cooled wall high-temperature superheating section 9; an evaporation section flat coil 6 is provided inside the boiler shell 1, located inside the coil water-cooled wall spiral coil 5; and a water inlet 13 is provided on the upper outer wall of the boiler shell 1, which is connected to the water inlet of the economizer flat coil 4.

[0028] The economizer flat coil 4, the water-cooled wall spiral coil 5, the evaporator section flat coil 6, the furnace water-cooled wall spiral coil 7, the steam-water separator 2, the furnace water-cooled wall low-temperature superheating section 8, the first water spray desuperheater 3, the furnace water-cooled wall high-temperature superheating section 9, and the second water spray desuperheater 3 are connected in sequence. The water flow direction of the water-cooled wall spiral coil 5 is from bottom to top; the economizer flat coil 4, the evaporator section flat coil 6, the furnace water-cooled wall spiral coil 7, the furnace water-cooled wall low-temperature superheating section 8, and the furnace water-cooled wall high-temperature superheating section 9 are all fed from top to bottom.

[0029] Feedwater inlet 13 is connected to a variable frequency plunger pump for boiler water supply via a pipeline. Boiler water that has been treated to meet boiler water quality requirements is pressurized by the variable frequency plunger pump and then fed into feedwater inlet 13.

[0030] The economizer flat coil 4 and the water-cooled spiral coil 5 form the heating section. The economizer flat coil 4 is the convective heating surface at the end of the boiler. The working fluid and flue gas are arranged in a counter-current manner, ensuring a higher average temperature and pressure, absorbing more heat, and improving boiler efficiency. The flue gas temperature in this section is low, and the working fluid inside the coil is single-phase liquid water, preventing excessively high tube wall temperatures. The boiler water, after being heated by the economizer flat coil 4, enters the water-cooled spiral coil 5. The structure of the water-cooled spiral coil 5 serves to isolate the high-temperature flue gas from the boiler shell; its heating area is relatively small, resulting in lower heat absorption.

[0031] The evaporation section consists of the flat coil 6 and the spiral coil 7 of the furnace water-cooled wall. Boiler water, heated by the spiral coil 5, enters the flat coil 6 of the evaporation section. The working fluid and flue gas are arranged in a counter-current flow. To accommodate the increased pipe diameter in subsequent evaporation sections, the specifications of the flat coils in this section gradually increase, resulting in a smoother flow velocity change within the tubes. In the evaporation section, the boiler water partially transforms from saturated water into saturated steam, coexisting as both vapor and liquid phases.

[0032] After passing through the steam-water separator 2, the high-dryness saturated steam returns to the low-temperature superheating section 8 of the furnace water-cooled wall, while the saturated water enters the deaerator tank through the condensate drainage system. Compared to the steam-water two-phase working fluid, the high-dryness steam causes less erosion and corrosion to the pipes in the low-temperature superheater section, thus offering higher safety.

[0033] Steam is heated in the low-temperature superheating section 8 of the furnace water-cooled wall and then flows through the water spray desuperheater 3 before entering the high-temperature superheating section 9 of the furnace water-cooled wall. Since the low-temperature superheater and the high-temperature superheater are divided into two sections, the high-temperature superheater can be made of a high-temperature resistant material, and the influence of welding dissimilar steels does not need to be considered.

[0034] The tube wall temperature of the high-temperature superheated section 9 of the furnace water-cooled wall is relatively high. A wall temperature sensor is installed on the tube of the high-temperature superheated section 9 of the furnace water-cooled wall to detect the wall temperature, and a high-temperature alarm connected to the wall temperature sensor is installed on the outside of the boiler shell 1.

[0035] A heat-resistant steel plate is installed between the inner wall of the boiler shell 1 and the low-temperature superheated section 8 and the high-temperature superheated section 9 of the furnace water-cooled wall. This isolates some of the heat, thereby reducing the temperature of the boiler shell 1 and lowering the requirements for the shell material.

[0036] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0040] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A once-through coil boiler with the superheating section located in the furnace, comprising a boiler shell (1), a steam-water separator (2), and a water spray desuperheater (3); a burner connection port (11) is provided at the lower end of the boiler shell (1); and a flue gas outlet (12) is provided at the upper end of the boiler shell (1). Its features are: The inner wall of the boiler shell (1) is provided with an economizer flat coil (4), a coil water-cooled wall spiral coil (5), a furnace water-cooled wall spiral coil (7), a furnace water-cooled wall low-temperature superheating section (8), and a furnace water-cooled wall high-temperature superheating section (9) in sequence from top to bottom; an evaporation section flat coil (6) is provided inside the boiler shell (1) on the inner side of the coil water-cooled wall spiral coil (5); The upper end of the outer wall of the boiler shell (1) is provided with a water inlet (13) that is connected to the water inlet end of the economizer flat coil (4); The economizer flat coil (4), the coil water-cooled wall spiral coil (5), the evaporation section flat coil (6), the furnace water-cooled wall spiral coil (7), the steam-water separator (2), the furnace water-cooled wall low-temperature superheating section (8), the first water spray desuperheater (3), the furnace water-cooled wall high-temperature superheating section (9), and the second water spray desuperheater (3) are connected in sequence.

2. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: The water flow direction of the spiral coil (5) of the water-cooled wall is from bottom to top; the economizer flat coil (4), the evaporation section flat coil (6), the furnace water-cooled wall spiral coil (7), the furnace water-cooled wall low-temperature superheated section (8) and the furnace water-cooled wall high-temperature superheated section (9) are all transported from top to bottom.

3. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: The water inlet (13) is connected to a variable frequency plunger pump for boiler water supply via a pipeline.

4. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: The economizer flat coil (4) and the coil water-cooled wall spiral coil (5) form a heating section.

5. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: The evaporation section flat coil (6) and the furnace water-cooled wall spiral coil (7) together form the evaporation section.

6. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: A heat-resistant steel plate is provided between the inner wall of the boiler shell (1) and the low-temperature superheated section (8) and the high-temperature superheated section (9) of the furnace water-cooled wall.

7. A once-through coil boiler with the superheated section located in the furnace according to claim 1, characterized in that: A wall temperature sensor is installed on the pipe of the high temperature superheat section (9) of the furnace water-cooled wall, and a high temperature alarm connected to the wall temperature sensor is installed outside the boiler shell (1).

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