A high-efficiency supercritical low-calorific value gas boiler with self-draining baffle temperature regulation

Abstract

A high-efficiency, supercritical, low-calorific-value gas-fired boiler with self-draining baffle temperature regulation belongs to the field of power and thermal energy technology. It comprises a furnace body, water-cooled walls, a sheathing wall, an upper economizer, a lower economizer, a tubular air preheater, a steam-water separator, an integrated evacuation and expansion system, a low-temperature superheater, a platen superheater, a high-temperature superheater, a low-temperature reheater, and a high-temperature reheater. The water-cooled walls and sheathing wall are mounted within the furnace body. The sheathing wall is equipped with an upper economizer, which is connected to a lower economizer. The lower economizer is equipped with a tubular air preheater. The upper economizer is connected to the water-cooled walls, which are connected to the steam-water separator and the integrated evacuation and expansion system. The steam-water separator is connected to the ceiling pipe. The sheathing wall is covered with a low-temperature superheater and a low-temperature reheater. The low-temperature superheater is connected to the ceiling pipe and the platen superheater. The platen superheater is connected to the high-temperature superheater, and the low-temperature reheater is connected to the high-temperature reheater. The invention solves the problems of low calorific value, low gas combustion temperature and weak radiation heat absorption of existing high-temperature gas boilers.

Description

Technical Field

[0001] The invention relates to a high-efficiency supercritical-fired low-calorific-value gas boiler with self-draining baffle temperature regulation, belonging to the technical field of electric power and thermal energy. Background Art

[0002] The efficient use of energy has always been a long-term concern in the field of electricity and thermal energy. Improving the steam parameters of the boiler is an effective way to improve energy utilization. Since the efficiency of the subcritical unit with a main steam pressure of 17.50MPa, a superheated steam temperature of 571℃, and a reheated steam temperature of 569℃ can reach 40.5%, the power supply gas consumption is reduced by 0.20Nm compared with the conventional ultra-high pressure parameter unit. 3 Therefore, further improvement of boiler temperature, pressure and other parameters will help to further improve the efficiency of the unit.

[0003] If the boiler outlet of the unit parameters is increased to supercritical, that is, the main steam pressure is increased to 25.4MPa, the superheated steam temperature is increased to 605℃ and the reheated steam temperature is increased to 603℃, then the gas consumption can be reduced compared with the ultra-high temperature subcritical parameters, and the power supply gas consumption can be reduced to 2.45Nm 3 / kw.h, which has achieved further efficient utilization of coal gas in steel enterprises and greatly reduced carbon emissions. However, due to the low calorific value, low coal gas combustion temperature and weak radiation heat absorption of existing high-temperature gas boilers, it is impossible to further improve the above-mentioned boiler parameters such as temperature and pressure.

[0004] Therefore, in order to meet the steel industry's demand for electricity and heat, it is very necessary to develop high-efficiency supercritical gas boilers that match small-capacity, high-parameter steam turbines and use blast furnace gas as fuel. Therefore, it is urgent to propose a new type of self-draining baffle temperature-regulating high-efficiency supercritical gas-fired low calorific value gas boiler to solve the above technical problems.

[0005] Therefore, it is urgent to propose a new type of high-efficiency supercritical low-calorific value gas boiler to solve the above technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a high-efficiency, supercritical, low-calorific-value gas-fired boiler with variable pressure operation, single-stage intermediate reheating, a single furnace, balanced ventilation, an all-steel frame suspension structure, and an open-air layout. This boiler addresses the problems of low calorific value, low gas combustion temperature, and weak radiant heat absorption experienced by existing high-temperature gas-fired boilers. A brief overview of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive overview of the invention. It is not intended to identify key or important aspects of the invention, nor is it intended to limit the scope of the invention.

[0007] The technical solution of the present invention:

[0008] A high-efficiency supercritical low-calorific value gas boiler with self-draining baffle temperature regulation, comprising a furnace body, a water-cooled wall, a wrapping wall, an upper economizer, a lower economizer, a tubular air preheater, a steam-water separator, an integrated expansion system, a low-temperature superheater, a screen superheater, a high-temperature superheater, a low-temperature reheater and a high-temperature reheater. The water-cooled wall and the wrapping wall are fixedly installed in the furnace body, the upper economizer is installed on the wrapping wall, the lower economizer is connected to the bottom of the upper economizer, the tubular air preheater is installed at the bottom of the lower economizer, the upper economizer is connected to the water-cooled wall, the water-cooled wall is connected to the steam-water separator and the integrated expansion system, the steam-water separator is connected to the ceiling pipe, the low-temperature superheater is arranged at the rear flue of the wrapping wall, the low-temperature superheater is respectively connected to the ceiling pipe and the screen superheater, the screen superheater is connected to the high-temperature superheater, the low-temperature reheater is installed at the front flue of the wrapping wall, and the low-temperature reheater is connected to the high-temperature reheater.

[0009] Preferably, the upper side of the water-cooled wall is a spiral tube coil water-cooled wall, the lower side of the water-cooled wall is a vertical tube panel water-cooled wall, and the spiral tube coil water-cooled wall and the vertical tube panel water-cooled wall are connected via a transition header.

[0010] Preferably, a burner is arranged in the furnace body below the water-cooled wall.

[0011] Preferably, the platen superheater is arranged at the furnace outlet of the furnace body, the platen superheater is connected to a small drain header, and the high-temperature superheater is connected to an intermediate mixing header.

[0012] Preferably, a first-stage desuperheater is provided between the low-temperature superheater and the platen superheater, a second-stage desuperheater is provided between the platen superheater and the high-temperature superheater, and the heating surfaces of the low-temperature superheater, the platen superheater and the high-temperature superheater are all arranged horizontally.

[0013] Preferably, the burner is a double-swirl low-NOx burner, and the left and right walls of the double-swirl low-NOx burner are arranged opposite each other.

[0014] Preferably, flue gas dampers are provided at the outlets of the low-temperature reheater and the low-temperature superheater.

[0015] The present invention has the following beneficial effects:

[0016] 1. The present invention ensures reasonable heat load data and water wall performance, and has strong unit capacity and fuel adaptability;

[0017] 2. The heating surface of the present invention can be completely hydrophobic, which can effectively prevent the blockage of high-temperature oxide scale and has a faster startup speed;

[0018] 3. The specifications and heat absorption ratios of the heating surfaces at each level of the present invention are reasonable, the structure is easy to implement, and the NOx emissions are low, ensuring the technological advancement of the boiler;

[0019] 4. The steam temperature of the boiler outlet superheater and reheater of the present invention is different from the traditional supercritical 571°C and 569°C, reaching 605°C and 603°C respectively, further improving the unit efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram for the installation of a high-efficiency supercritical low-calorific value gas boiler with a self-draining baffle and temperature regulation;

[0021] In the figure, 1-furnace body, 2-water-cooled wall, 3-envelope wall, 4-upper economizer, 5-lower economizer, 6-tubular air preheater, 7-steam-water separator, 8-integrated expansion system, 9-low-temperature superheater, 10-platen superheater, 11-high-temperature superheater, 12-low-temperature reheater, 13-high-temperature reheater, 14-ceiling pipe, 15-vertical water-cooled wall, 16-burner, 17-flue gas damper. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0023] The connections mentioned in the present invention are divided into fixed connections and detachable connections. The fixed connection refers to a non-detachable connection, including but not limited to conventional fixed connection methods such as hem connection, rivet connection, adhesive connection, and welding connection. The detachable connection refers to but not limited to conventional detachable connection methods such as threaded connection, snap connection, pin connection, and hinge connection. When the specific connection method is not clearly specified, it is assumed that at least one connection method can always be found among the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example, a welded connection is selected for a fixed connection, and a hinge connection is selected for a detachable connection.

[0024] Specific implementation method 1: Combination Figure 1 This embodiment is described. A high-efficiency supercritical low-calorific value gas-fired boiler with self-draining baffle temperature regulation includes a furnace body 1, a water-cooled wall 2, a wrapping wall 3, an upper economizer 4, a lower economizer 5, a tubular air preheater 6, a steam-water separator 7, an integrated drainage and expansion system 8, a low-temperature superheater 9, a platen superheater 10, a high-temperature superheater 11, a low-temperature reheater 12, and a high-temperature reheater 13.

[0025] The furnace body 1 is fixed with a water-cooled wall 2 and a wrapping wall 3, and an upper economizer 4 is installed on the wrapping wall 3. The lower side of the upper economizer 4 is reserved for SCR denitrification space. The economizer adopts a hierarchical arrangement in which the bottom of the upper economizer 4 is connected to the lower economizer 5 to ensure that the flue gas temperature at the denitrification inlet meets the low load operation requirements. The upper economizer 4 is fixed by support, and the lower economizer 5 is fixed by hanging; the economizer adopts a spiral fin structure with strong heat exchange capacity. The bottom section is equipped with a tubular air preheater 6. The upper economizer 4 is connected to the water-cooled wall 2. The water-cooled wall 2 is connected to a steam-water separator 7 and an integrated expansion system 8. The steam-water separator 7 is connected to the ceiling pipe 14. The superheater system adopts a three-stage layout. The rear flue of the enclosure wall 3 is equipped with a low-temperature superheater 9. The low-temperature superheater 9 is connected to the ceiling pipe 14 and the platen superheater 10 respectively. The platen superheater 10 is connected to the high-temperature superheater 11. The front flue of the enclosure wall 3 is equipped with a low-temperature reheater 12. The low-temperature reheater 12 is connected to the high-temperature reheater 13 using a support and fixing structure. The high-temperature reheater 13 adopts a countercurrent arrangement to shorten the length of the connecting pipes and the hot reheating pipe. The flue gas damper 17 is arranged at the outlet of the low-temperature reheater 12 and the low-temperature superheater 9. It controls the reheated steam temperature when the boiler load changes and the reheated steam temperature fluctuates below or above the set value. The heating surfaces of the low-temperature reheater 12 and the high-temperature reheater 13 are both arranged horizontally, which can ensure complete water drainage and effectively prevent clogging by high-temperature oxide scale.

[0026] The platen superheater 10 is suspended from the heating surface of the furnace 1 and is located at the furnace outlet. It is connected to a small drain header, while the high-temperature superheater 11 is connected to an intermediate mixing header to minimize temperature deviations. A burner 16 is located within the furnace 1 below the water-cooled wall 2. Flue gas dampers 17 are installed at the outlets of both the low-temperature reheater 12 and the low-temperature superheater 9 to adjust the flue gas flow distribution within the low-temperature reheater to ensure the reheat steam temperature reaches the rated value.

[0027] The superheated steam temperature is controlled by the gas-water ratio and two-stage water spray cooling, that is, a first-stage cooler is provided between the low-temperature superheater 9 and the platen superheater 10, and a second-stage cooler is provided between the platen superheater 10 and the high-temperature superheater 11. The heating surfaces of the low-temperature superheater 9, the platen superheater 10 and the high-temperature superheater are all arranged horizontally, which can ensure complete water drainage and effectively prevent clogging by high-temperature oxide scale.

[0028] The burner 16 is a double swirl low NOx burner, and the left and right walls of the double swirl low NOx burner are arranged opposite each other, so that the temperature field in the furnace body 1 is uniform, which can effectively shorten the layout length of the hot air duct and effectively reduce the depth of the boiler.

[0029] The lower side of the water-cooled wall 2 and the boiler ash hopper of the furnace body 1 are both spiral tube water-cooled walls. The upper side of the water-cooled wall 2 is a vertical tube panel water-cooled wall 15, which is connected to the vertical tube panel water-cooled wall 15 via a transition header. The spiral tube panel water-cooled wall utilizes an expandable vertical rigid beam system with tension plates. The spiral tubes of the spiral tube panel water-cooled wall are suspended by tension plates uniformly attached to the outer surface of the tube wall. The tension plates are arranged from the bottom of the furnace ash hopper to the transition zone between the spiral tubes and the vertical tube panel water-cooled wall 15. In this transition zone, the weight load is evenly transferred to the upper vertical tube panel of the vertical tube panel water-cooled wall 15 via comb-shaped suspension plates. The deadweight load of the rigid beam system and the furnace wall is completely supported by vertical lap plates, so the load of the lower furnace of the furnace body 1 and the boiler ash hopper can be transferred to the vertical tube panel water-cooled wall 15.

[0030] The integrated dredging and expansion system 8 is a startup system that adopts an atmospheric expansion tank type. The system is simple and easy to maintain. The atmospheric expansion tank and the drain tank are designed in an integrated manner to realize the boiler span arrangement of the integrated dredging and expansion system 8.

[0031] The tubes in the same tube band of the spiral tube coil water-cooled wall pass around the corners and middle parts of the furnace in the furnace body 1 from bottom to top in the same way. It has strong applicability and sufficient cooling capacity under various loads. Since it can effectively compensate for thermal deviations along the circumference of the furnace, the hydrodynamic characteristics are stable.

[0032] Here’s how it works:

[0033] This embodiment mainly transfers the combustion heat of the fuel through the internal heating surface of the furnace body 1 to the energy transfer medium inside the heating surface. The energy transfer medium can be water or water vapor.

[0034] High-temperature, high-pressure steam is efficiently converted into electricity through the steam turbine generator set, completing the efficient conversion of fuel combustion heat into electricity. On the flue gas side, the fuel and high-temperature air from the outlet of the tubular air preheater 6 are burned within the furnace body 1, passing through the various heating surfaces within the furnace body 1 in sequence, and finally discharged through the air preheater. The primary steam, or superheated steam, passes through the upper economizer 4, lower economizer 5, water-cooled wall 2, steam-water separator 7, envelope wall 3, low-temperature superheater 9, platen superheater 10, and high-temperature superheater 11, finally entering the high-pressure cylinder of the steam turbine through the main steam pipe to generate electricity. On the secondary steam, or reheated steam, exhaust steam from the high-pressure cylinder passes through the cold reheat pipe, sequentially entering the low-temperature reheater 12 and high-temperature reheater 13, and finally through the hot reheat pipe to enter the intermediate-pressure cylinder of the steam turbine to generate electricity.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0037] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0038] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0039] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0040] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0041] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A high-efficiency supercritical low-calorific value gas boiler with self-draining baffle temperature regulation, characterized by: The invention comprises a furnace body (1), a water-cooled wall (2), a wrapping wall (3), an upper economizer (4), a lower economizer (5), a tubular air preheater (6), a steam-water separator (7), an integrated expansion system (8), a low-temperature superheater (9), a screen superheater (10), a high-temperature superheater (11), a low-temperature reheater (12) and a high-temperature reheater (13). The furnace body (1) is fixedly provided with a water-cooled wall (2) and a wrapping wall (3). The wrapping wall (3) is provided with an upper economizer (4). The lower economizer (5) is connected to the bottom of the upper economizer (4). The lower economizer (5) is provided with a tubular air preheater ( 6), the upper economizer (4) is connected to the water-cooled wall (2), the water-cooled wall (2) is connected to a steam-water separator (7) and an integrated expansion system (8), the steam-water separator (7) is connected to a ceiling pipe (14), the rear flue of the wall (3) is arranged with a low-temperature superheater (9), the low-temperature superheater (9) is connected to the ceiling pipe (14) and the platen superheater (10), the platen superheater (10) is connected to the high-temperature superheater (11), the front flue of the wall (3) is installed with a low-temperature reheater (12), and the low-temperature reheater (12) is connected to the high-temperature reheater (13); The lower side of the water-cooled wall (2) is a spiral tube coil water-cooled wall, and the upper side of the water-cooled wall (2) is a vertical tube screen water-cooled wall (15). The spiral tube coil water-cooled wall and the vertical tube screen water-cooled wall (15) are connected through a transition header; a burner (16) is arranged in the furnace body (1) below the water-cooled wall (2); the platen superheater (10) is arranged at the furnace outlet of the furnace body (1), the platen superheater (10) is connected to a small drain header, and the high-temperature superheater (11) is connected to an intermediate mixing header. High-temperature and high-pressure steam is efficiently converted into electrical energy through a steam turbine generator set, wherein on the flue gas side, the fuel and the outlet of the tubular air preheater (6) are High-temperature air is burned in the furnace body (1), passes through the various heating surfaces in the furnace body (1) in sequence, and is finally discharged through the air preheater; the primary steam, i.e. the superheated steam side, passes through the upper economizer (4), the lower economizer (5), the water-cooled wall (2), the steam-water separator (7), the wall (3), the low-temperature superheater (9), the platen superheater (10) and the high-temperature superheater (11) in sequence, and finally enters the high-pressure cylinder of the steam turbine through the main steam pipe to generate electricity; the secondary steam, i.e. the reheated steam side, the exhaust steam from the high-pressure cylinder passes through the cold reheat pipe and enters the low-temperature reheater (12) and the high-temperature reheater (13) in sequence, and then enters the intermediate-pressure cylinder of the steam turbine through the hot reheat pipe to generate electricity.

2. The high-efficiency supercritical low-calorific value gas boiler with self-draining baffle temperature regulation according to claim 1, characterized in that: A primary desuperheater is provided between the low-temperature superheater (9) and the platen superheater (10), and a secondary desuperheater is provided between the platen superheater (10) and the high-temperature superheater (11). The heating surfaces of the low-temperature superheater (9), the platen superheater (10) and the high-temperature superheater are all arranged horizontally.

3. The self-draining baffle temperature-regulating high-efficiency supercritical low-calorific value gas boiler according to claim 2, characterized in that: The burner (16) is a double-swirl low-NOx burner, and the left and right walls of the double-swirl low-NOx burner are arranged in opposition.

4. The self-draining baffle temperature-regulating high-efficiency supercritical low-calorific value gas boiler according to claim 3, characterized in that: Flue gas dampers (17) are provided at the outlets of the low-temperature reheater (12) and the low-temperature superheater (9).

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