A boiler system with enhanced load carrying

Abstract

The utility model provides a kind of can promote the boiler system of load, including boiler, the hearth bottom of boiler is equipped with at least two symmetrical combustion device arranged in two sides, the central position of hearth is vertically arranged a water cooling screen, the water cooling screen is made of multiple parallel arrangement heat exchange tube, its bottom end is connected with lower header, its top is provided with Y type bifurcation structure, the bifurcation structure divides the water cooling screen into left and right two groups of tube bundle, two groups of tube bundle respectively passes out the hearth top of boiler and is adjacent with upper header.The utility model is equipped with water cooling screen, increases the heating area, promotes the evaporation capacity of boiler system, Y type bifurcation structure of water cooling screen top effectively prolongs flue gas path, promotes combustion, so that in the load promotion, hearth temperature is reduced instead.The root of coking is fundamentally checked.

Description

Technical Field

[0001] This utility model relates to the field of boiler equipment technology, specifically to a boiler system capable of increasing load capacity. Background Technology

[0002] A boiler is a thermal energy conversion device that heats water into steam. Its core lies in the efficient heat exchange between the steam-water system and the flue gas system, and it is widely used in industrial heating and power generation. A typical boiler system includes core components such as the furnace, burner, boiler drum, headers, water-cooled walls, superheater, and economizer. The steam-water system process is as follows: After softening and deoxygenating, feedwater is pressurized and sent into the boiler drum by the boiler feedwater pump. It then flows into the lower header through the downcomer and is distributed to the water-cooled wall tubes and convection tube bundles around the furnace for heat absorption and evaporation. The resulting steam-water mixture rises into the upper and top headers and finally returns to the boiler drum for steam-water separation. Saturated steam is drawn out, enters the superheater through the steam distribution header, and is heated to become superheated steam, which is then delivered to the user. Meanwhile, the flue gas system follows this path: fuel is burned in the furnace by the burner to produce high-temperature flue gas. After releasing a large amount of radiant heat in the furnace, the flue gas flows sequentially through the slag-forming tubes, burnout chamber, convection tube bundle, superheater and other heating surfaces for convective heat exchange. Then it flows through the economizer and air preheater to recover waste heat, and finally is discharged into the atmosphere by the induced draft fan through the chimney.

[0003] In actual operation, insufficient design of the boiler's evaporation heating surface area can lead to problems such as excessively high furnace temperature, coking, increased flue gas temperature, and reduced load-carrying capacity during high-load operation. The existing JNG-MF boiler is a typical example of this structure. During high-load operation with an evaporation rate of approximately 35 T / h, the furnace temperature reaches around 1200℃, and the tail-end flue gas temperature is approximately 170℃, both exceeding ideal values. Analysis shows that the root cause of this problem lies in the insufficient area of ​​the original design's evaporation heating surface (i.e., water-cooled wall). When the boiler undergoes combined lifting, the water-cooled wall cannot absorb enough heat, resulting in an abnormally high furnace temperature. This temperature not only far exceeds the melting temperature of the ash and slag (approximately 1150℃), causing severe coking at the bottom of the furnace and on the water-cooled wall, affecting the normal operation of the boiler, but also increases flue gas heat loss and reduces thermal efficiency. Ultimately, this prevents the boiler from reaching its rated evaporation capacity of 40 T / h, failing to meet user requirements.

[0004] Therefore, in order to solve the problems of furnace overheating, coking, and limited processing caused by insufficient heating surface, it is urgent to improve the boiler body structure to enhance the boiler's heat absorption capacity, thereby ensuring that it can reach the rated processing capacity and operate safely and stably. Utility Model Content

[0005] The purpose of this invention is to provide a boiler system capable of increasing load capacity. By adding a water-cooled screen, the heating area is increased, thereby enhancing the evaporation capacity of the boiler system. The Y-shaped branching structure at the top of the water-cooled screen effectively extends the flue gas path, promoting combustion and thus reducing the furnace temperature while increasing the load. This fundamentally curbs the root cause of coking.

[0006] To achieve the above objectives, the present invention proposes the following technical solution:

[0007] A boiler system capable of increasing load capacity includes a boiler. The boiler has at least two burners symmetrically arranged on both sides at the bottom of the furnace. A water-cooled screen is vertically arranged at the center of the furnace. The water-cooled screen is composed of multiple parallel heat exchange tubes. Its bottom end is connected to a lower header, and its top is configured with a Y-shaped bifurcation structure. The bifurcation structure divides the water-cooled screen into left and right groups of tube bundles. The two groups of tube bundles respectively extend out of the top of the boiler and are adjacent to an upper header.

[0008] As a preferred technical solution of this utility model, the bifurcation structure is symmetrical from left to right, and the two groups of tubes on the left and right extend upward and to both sides at an inclination angle of 135°-145°.

[0009] As a preferred embodiment of this utility model, the bending radius at the bifurcation of the heat exchange tube is not less than 3.5 times its nominal diameter.

[0010] As a preferred embodiment of this utility model, the heat exchange tube is a finned tube.

[0011] As a preferred embodiment of this utility model, two independent openings are provided on the furnace top for the top end of the tube bundle to be led out, and the space between the opening and the tube bundle passing through it is filled with a flexible sealing material.

[0012] As a preferred embodiment of this utility model, the water-cooled screen is arranged at the midpoint of the connection between the two burners.

[0013] As can be seen from the above technical solutions, the technical solution of this utility model provides...

[0014] The outlet of the water-cooled screen tube assembly is divided into two groups, which avoids opening a single-diameter hole with a very large span on the furnace top. This effectively protects the structural integrity of the furnace top and prevents deformation during operation due to excessively large openings and weakened strength.

[0015] By placing the water-cooled screen in the middle of the two sets of burners in the boiler, the original integrated combustion in the furnace is divided into two relatively independent combustion zones, making the combustion agitation in each combustion zone more intense and conducive to forming better combustion conditions.

[0016] The Y-shaped structure is equivalent to adding a diverter plate in the middle of the furnace, extending the upward path and residence time of the high-temperature flue gas. This allows for more complete combustion of carbonaceous particles in the fly ash, thereby improving the boiler's combustion efficiency and economy. Furthermore, the Y-shaped bifurcated structure can better absorb and compensate for the upward thermal expansion of the water-cooled screen tube bundle when heated, reducing thermal stress and ensuring the reliability of system operation.

[0017] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered as part of the utility model subject matter of this disclosure, provided that such concepts do not contradict each other.

[0018] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0019] The accompanying drawings are not drawn to scale according to a true reference numeral. In the drawings, each identical or nearly identical component shown in the various figures can be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0020] Figure 1 This is a front view of the internal structure of the boiler system according to an embodiment of the present utility model;

[0021] Figure 2 This is a side view of the internal structure of the boiler system according to an embodiment of the present utility model;

[0022] Figure 3 This is a top view of the internal structure of the boiler system according to an embodiment of the present invention.

[0023] 1. Boiler, 2. Burner, 3. Water-cooled screen, 4. Lower header, 5. Flow hole, 6. Upper header, 7. Boiler drum. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model without creative effort are within the scope of protection of this utility model. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this utility model pertains.

[0025] The terms "first," "second," and similar words used in this utility model patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] like Figure 1-3 As shown, this utility model provides a boiler system that can improve load capacity, which can solve the problems of poor load capacity and serious coking in the furnace caused by insufficient evaporation heating surface of existing boilers.

[0027] The boiler system includes a boiler 1, which includes a furnace composed of a membrane water-cooled wall, at least two swirl burners installed at the bottom of the furnace, and a boiler drum 7 located outside the furnace top. The core improvement of this utility model is that a water-cooled screen 3 is vertically installed at the center of the furnace, that is, on the line connecting the two burners 2.

[0028] The water-cooled screen 3 consists of 20-26 parallel heat exchange tubes, preferably finned tubes. The finned tube structure effectively increases the heat exchange area and enhances the overall rigidity of the screen, preventing flutter and inter-tube friction during operation. A lower header 4 is connected to the bottom of the water-cooled screen 3, and the boiler feedwater is introduced into the lower header 4 through a pipe.

[0029] The top of the water-cooled screen 3 adopts a unique Y-shaped bifurcation structure. Specifically, the heat exchange tubes that make up the water-cooled screen 3 are equally divided into two groups of tube bundles. When the two groups of tube bundles approach the top of the boiler 1, they symmetrically bifurcate to the left and right sides to form two groups of tube bundles. These groups of tube bundles pass through two independent openings 5 ​​pre-drilled on the top of the boiler 1 and lead out to the outside of the furnace to connect with the upper header 6.

[0030] The bifurcation of the two sets of tube bundles is symmetrical. The bifurcation point is located at a certain distance below the top of the furnace, such as 1-1.5m from the inner surface of the furnace top. Each set of tube bundles extends upward and to both sides at a certain angle. The preferred range of the angle is 135°-145°, which is the result of optimization through fluid and structural simulation. If the angle is too small, the effect of diverting and extending the flue gas path will be insignificant; if the angle is too large, it will lead to a significant increase in flow resistance and place higher demands on the sealing and strength design of the relief hole 5 at the furnace top.

[0031] The heat exchange tubes at the bifurcation point are manufactured using a smooth bending process, such as hot bending or cold bending, with a bending radius R not less than 3.5 times the heat exchange tube diameter D, i.e., R ≥ 3.5D. This large bending radius design effectively reduces the local resistance to the working fluid flow and minimizes stress concentration at the bifurcation point, thereby improving the fatigue resistance of the tube panel under boiler start-up and shutdown conditions and load fluctuations.

[0032] When the left and right sets of tube bundles pass through the relief holes 5 on the furnace top, their centerlines coincide with the centerline of the relief holes 5. The relief holes 5 are elliptical or circular, preferably elliptical, and their dimensions are slightly larger than the outer dimensions of the tube bundles. A flexible sealing material, such as ceramic fiber rope or high-temperature sealant, is filled between the relief holes 5 and the tube bundles. This design provides the necessary displacement space for the thermal expansion of the tube bundles while ensuring the sealing of the furnace top and preventing air and smoke leakage.

[0033] In some specific embodiments of this utility model, limiting and guiding devices are provided near the bifurcation point of the tube bundle and / or below the relief hole 5 on the furnace top. This device does not restrict the free vertical expansion of the tube bundle, but it can limit its horizontal sway, further suppressing possible vibrations and ensuring the long-term stability and reliability of the Y-shaped structure. The heat exchange tubes, lower header 4, and upper header of the water-cooled screen 3 are made of the same or compatible materials as the original water-cooled wall of the boiler to ensure consistent expansion coefficients and good welding performance. All connections are made by welding to ensure the sealing strength and reliability of the pressure-bearing components.

[0034] The upper header 6 is connected to the upper header of the original water-cooled wall of the boiler 1 through a connecting pipe, or directly connected to the boiler drum 7 through a connecting pipe, and finally the steam-water mixture generated in the water-cooled screen 3 is fed into the boiler drum 7 of the boiler 1 for steam-water separation.

[0035] The working process of this utility model is as follows:

[0036] Boiler feedwater enters from the lower header 4. As it flows through the heat exchange tubes of the water-cooled wall 1, it absorbs the radiant heat from the high-temperature flames at the center of the furnace, and some of the water evaporates to form a steam-water mixture. Due to the density difference, the steam-water mixture naturally flows upward and, through the Y-shaped branching structure at the top, exits through two vents on the left and right sides, flowing out of the furnace top and converging into the upper header 6. Finally, it enters the boiler drum 7 together with the working fluid of the boiler's original water-cooled wall system.

[0037] Example 1

[0038] To better illustrate the technical solution and effects of this utility model, the following provides a specific embodiment applied to a JNG-40 / 3.82 / 450-MF model boiler in a power plant.

[0039] This boiler is a vertical single-drum pulverized coal boiler with a rated evaporation capacity of 40T / h. After being put into operation, it has been unable to reach its designed output due to the problem of coking in the furnace for a long time. The maximum continuous evaporation capacity can only be maintained at about 35T / h. The furnace temperature is 1200℃ and the flue gas temperature is about 170℃.

[0040] To address the aforementioned issues, the boiler underwent the following technical improvements: a water-cooled screen consisting of 26 heat exchange tubes was installed at the very center of the furnace, along the midline connecting the two burners. The tubes are seamless boiler-grade steel tubing with a specification of Ф60mm × 4mm, and a finned tube structure was adopted to enhance rigidity and heat transfer, with fins 10mm wide and 3mm thick. Based on this calculation, the total heat-receiving area of ​​the water-cooled screen installed in this embodiment is approximately 50 square meters.

[0041] The bottom of the water-cooled screen is welded to a lower header (Ф273mm×16mm), through which boiler feedwater is introduced. The top of the water-cooled screen features a unique Y-shaped bifurcated structure. Specifically, 26 tubes begin approximately 1.2m from the inner surface of the furnace top and symmetrically bifurcate to the left and right at a 135° angle, with a bending radius of 210mm. This bifurcation forms two sets of tube bundles, each with 13 tubes, which pass through two elliptical openings on the furnace top. Ceramic fiber ropes are used to fill and seal the gaps between the openings and the tube bundles.

[0042] After the two sets of tube bundles are led out from the furnace top, they are connected to an upper header (Ф273mm×16mm). This upper header is connected in parallel with the upper header of the boiler's original water-cooled wall through connecting pipes. Finally, the working fluid is introduced into the boiler drum.

[0043] To monitor the effectiveness of the modification, the inter-tube operating parameters before and after the modification were compared under the same boiler load range (40T / h), as shown in Table 1.

[0044] Table 1

[0045] Maximum continuous evaporation ~35T / h 40T / h Achieve rated design output Furnace center temperature ~1200℃ ≤1140℃ Lowering the temperature to below the ash melting point (1150℃) effectively inhibits coking. Tail exhaust temperature ~170℃ 148℃ Significantly reduces heat loss and improves efficiency. Coking in the furnace serious slight The frequency of needing regular descaling has been greatly reduced.

[0046] As shown in the data above, this utility model effectively increases the total evaporation heating area of ​​the boiler by adding a Y-shaped water-cooled screen in the center of the furnace, increasing the heating area by approximately 50 square meters. The modified boiler can stably reach its rated evaporation capacity of 40 T / h, while the furnace center temperature drops below the ash melting point of 1150℃, effectively suppressing coking. The exhaust gas temperature also decreases to 150℃, significantly improving the boiler's safety, economy, and load-bearing capacity.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A boiler system capable of lifting load, comprising a boiler (1), the hearth bottom of the boiler (1) is provided with at least two burners (2) symmetrically arranged on both sides, characterized in that, A water-cooled screen (3) is vertically installed at the center of the furnace. The water-cooled screen (3) is composed of multiple parallel heat exchange tubes. Its bottom end is connected to a lower header (4), and its top is set with a Y-shaped bifurcation structure. This bifurcation structure divides the water-cooled screen (3) into two groups of tube bundles, and the two groups of tube bundles pass through the top of the boiler (1) and are adjacent to an upper header (6).

2. The liftable load-bearing boiler system of claim 1, wherein, The bifurcation structure is symmetrical from left to right, with the two sets of tubes extending upward and to both sides at an angle of 135°-145°.

3. The lift capable hydronic boiler system of claim 1, wherein, The bending radius at the bifurcation of the heat exchange tube is not less than 3.5 times its nominal diameter.

4. The lift capable hydronic boiler system of claim 1, wherein, The heat exchange tube is a finned tube.

5. The liftable load-bearing boiler system of claim 1, wherein, Two independent openings (5) are provided on the top of the furnace for the top of the tube bundle to be led out. The openings (5) and the tube bundle passing through them are filled with a flexible sealing material.

6. The lift capable hydronic boiler system of claim 1, wherein, The water-cooled screen (3) is positioned at the midpoint of the line connecting the two burners (2).

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