A tangentially fired secondary reheat T-type boiler

Abstract

A tangential combustion secondary reheat T-type boiler relates to secondary reheat boiler technology. In order to solve the problem that the primary reheat and secondary reheat in the existing secondary reheat boiler are arranged in sequence, so that the heat transfer temperature difference cannot meet the heat exchange needs. In the present invention, the left horizontal flue and the right horizontal flue are respectively connected to the left and right flue gas outlets of the furnace, the left tail vertical flue is connected to the left horizontal flue, and the right tail vertical flue is connected to the right horizontal flue; the partition screen superheater is installed above the furnace, and the burner is installed on the outer wall of the furnace; a high-temperature superheater and a primary reheat high-temperature reheater are arranged in the left horizontal flue; a high-temperature superheater and a secondary reheat high-temperature reheater are arranged in the right horizontal flue; a primary reheat low-temperature reheater, a low-temperature superheater and an economizer are arranged in the left tail vertical flue; a secondary reheat low-temperature reheater, a low-temperature superheater and an economizer are arranged in the right tail vertical flue. The present invention is used to meet the heat exchange needs of the heat transfer temperature difference.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary reheat boilers, and in particular to a tangentially fired secondary reheat T-type boiler. Background Art

[0002] The higher the steam parameters of power plant boilers, the more frequent the heating cycles, and the more efficient the thermal cycle. The continuous development of the power industry, coupled with the increasing demand for economical, efficient, and energy-efficient generator sets, has driven the development of power plant boilers to ever-higher parameters. The evolution from subcritical boilers to supercritical and ultra-supercritical boilers has quickly transitioned to highly efficient ultra-supercritical single-reheat boilers. The boiler's main steam temperature has been raised to 605°C, and the reheat steam temperature to 623°C. The implementation of double-reheat technology on this basis can further improve unit economics, increasing thermal efficiency by approximately 1.5% to 2.0%, significantly reducing boiler coal consumption, and conserving energy. Double-reheat boilers are a highly efficient, low-pollution coal-fired power generation technology with strong market competitiveness.

[0003] Compared with the single-stage reheat boiler, the secondary reheat boiler has an additional reheater system and an additional high-temperature heating surface. In this way, the secondary reheat boiler has three heating surfaces with outlet steam temperatures exceeding 600°C, which increases the difficulty of matching the furnace with the heating surface. The existing secondary reheat boiler layout types include Π-type layout and tower layout. The high-temperature heating surfaces of these two layout types are arranged in sequence along the flue gas flow direction, namely, high-temperature superheater, single-stage reheat high-temperature reheater, and secondary reheat high-temperature reheater. The heat transfer temperature difference of the last secondary reheat high-temperature reheater is small, especially at low load, as the flue gas temperature decreases, the heat transfer temperature difference is even smaller, resulting in the rated steam temperature not being reached at low load. In order to enhance the temperature control capability, the secondary reheat boiler has a variety of temperature control methods, including double-channel flue gas dampers, swinging burners, flue gas recirculation and other temperature control methods.

[0004] For boilers with a reheat steam temperature of 623°C, the problem of low-load heat exchange can be solved by using double-flue flue gas dampers, swing burners, and flue gas recirculation. As the reheat steam temperature continues to increase, the current reheat steam temperature has increased to 633°C, and the next target will be to increase it to 650°C~720°C. If the sequential arrangement is still used, the inlet flue gas temperature of the secondary reheat high-temperature reheater will drop to about 750°C at low load, and the outlet flue gas temperature will be about 700°C. The heat transfer temperature difference cannot meet the heat exchange needs. Solving the problem of heat transfer temperature difference has become the key to whether the reheat steam temperature can be further increased. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the high-temperature superheater, the primary reheat high-temperature reheater and the secondary reheat high-temperature reheater in the existing secondary reheat boiler are arranged in sequence, so that the heat transfer temperature difference cannot meet the heat exchange requirements; and thus a tangentially fired secondary reheat T-type boiler is provided.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A tangentially fired, double-reheat T-type boiler comprising a furnace, a left horizontal flue, a right horizontal flue, a left rear vertical flue, a right rear vertical flue, a partition screen superheater, two high-temperature superheaters, a primary reheat high-temperature reheater, a primary reheat low-temperature reheater, two low-temperature superheaters, two economizers, two air preheaters, a secondary reheat high-temperature reheater, a secondary reheat low-temperature reheater, and a burner;

[0008] The left horizontal flue and the right horizontal flue are respectively connected to the left and right flue gas outlets of the furnace, the left tail vertical flue is communicated with the left horizontal flue, and the right tail vertical flue is communicated with the right horizontal flue; the partition screen superheater is installed above the furnace, and the burner is installed on the outer wall of the furnace; a high-temperature superheater and a first-reheat high-temperature reheater are arranged in sequence along the direction of flue gas flow in the left horizontal flue; a high-temperature superheater and a second-reheat high-temperature reheater are arranged in sequence along the direction of flue gas flow in the right horizontal flue; a first-reheat low-temperature reheater, a low-temperature superheater and an economizer are arranged in the left tail vertical flue; a second-reheat low-temperature reheater, a low-temperature superheater and an economizer are arranged in the right tail vertical flue; the two air preheaters are respectively arranged at the tail of the left tail vertical flue and the right tail vertical flue.

[0009] Furthermore, the furnace is surrounded by water-cooled walls, which include interconnected spiral tube ring water-cooled walls and vertical tube ring water-cooled walls. The upper parts of the water-cooled walls on both sides of the furnace are bent to form two left and right flame deflection angles; the two high-temperature superheaters are respectively arranged at the left and right flame deflection angles on the upper part of the furnace.

[0010] Furthermore, the partition screen superheater is arranged in the radiation zone of the furnace and is arranged symmetrically in the center.

[0011] Furthermore, the left rear vertical flue and the right rear vertical flue are both double flue structures, the left rear vertical flue includes a left first flue and a left second flue, the primary reheat low-temperature reheater is arranged in the left first flue, and the low-temperature superheater and economizer are arranged in sequence in the left second flue along the flue gas flow direction;

[0012] The right tail vertical flue includes the right flue one and the right flue two. The secondary reheating low-temperature reheater is arranged in the right flue one, and the low-temperature superheater and economizer are arranged in the right flue two in sequence along the flue gas flow direction.

[0013] Furthermore, a rear flue gas baffle is respectively arranged at the bottom of the double flues of the left rear vertical flue and the bottom of the double flue of the right rear vertical flue.

[0014] Furthermore, the burner is a direct current burner, which adopts a single tangential circle or double tangential circle combustion mode.

[0015] Furthermore, the T-type boiler further comprises a steam-water separator, a water storage tank and a recirculation pump; the steam-water separator, the water storage tank and the recirculation pump are installed on one side outside the furnace; the water outlet of the steam-water separator is connected to the water inlet of the water storage tank, the water outlet of the water storage tank is connected to the water inlet of the recirculation pump, the water outlet of the recirculation pump is respectively connected to the water inlets of two economizers, the water outlets of the two economizers are connected to the water inlet of the furnace water-cooled wall, the water outlet of the furnace water-cooled wall is connected to the water inlet of the steam-water separator, the steam outlet of the steam-water separator is respectively connected to the steam inlets of two low-temperature superheaters, the steam outlets of the two low-temperature superheaters are respectively connected to the steam inlet of the partition screen superheater, the partition screen The steam outlet of the superheater is connected to the steam inlet of the two high-temperature superheaters respectively, the steam outlets of the two high-temperature superheaters are connected to the steam inlet of the high-pressure cylinder of the steam turbine respectively, the steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the single-reheat low-temperature reheater, the steam outlet of the single-reheat low-temperature reheater is connected to the steam inlet of the single-reheat high-temperature reheater, the steam outlet of the single-reheat high-temperature reheater is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine, the steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the secondary-reheat low-temperature reheater, the steam outlet of the secondary-reheat low-temperature reheater is connected to the steam inlet of the secondary-reheat high-temperature reheater, and the steam outlet of the secondary-reheat high-temperature reheater is connected to the steam inlet of the low-pressure cylinder of the steam turbine.

[0016] The beneficial effects of the present invention compared with the prior art are:

[0017] 1. The boiler of this invention adopts a T-shaped layout, placing both the primary and secondary high-temperature reheaters in close proximity to the high-temperature superheater at the furnace outlet. This increases the heat transfer temperature difference, helps ensure the rated steam temperature, enhances the thermostatic performance of the secondary reheat boiler, and creates conditions for further improving steam parameters. During operation, the primary reheat steam temperature is adjusted by the left rear flue gas damper, and the secondary reheat steam temperature is adjusted by the right rear flue gas damper. The combined adjustment of the left and right rear flue gas dampers adjusts the heat distribution between the superheater, primary reheat, and secondary reheat, thereby achieving reheat steam temperature regulation over a wide load range. The swing of the burner serves as an auxiliary thermostatic means, which can help adjust the steam temperature in situations such as changes in coal quality.

[0018] 2. The boiler of the present invention adopts a starting system with a recirculation pump. At the initial start-up stage, the water separated by the steam-water separator enters the water storage tank, and is then pressurized by the recirculation pump and sent back to the water supply pipe, forming a recirculation operation mode. When the DC load is reached, the recirculation pump and its recirculation pipeline stop running.

[0019] 3. The boiler capacity of the present invention is 600MW-1300MW, and the outlet steam temperature of the superheater, primary reheater and secondary reheater is 600℃-720℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are part of this application and are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention but do not constitute improper limitations on the present invention.

[0021] Figure 1 It is a front view of the general arrangement of the present invention;

[0022] Figure 2 It is a layout diagram of the startup system of the present invention;

[0023] Figure 3 It is a schematic diagram of the flue arrangement of the present invention;

[0024] Figure 4 Schematic diagram of the working medium heat exchange system of the present invention.

[0025] In the figure: 1. Furnace; 2. Divider screen superheater; 3. High-temperature superheater; 4. Single-reheat high-temperature reheater; 5. Single-reheat low-temperature reheater; 6. Low-temperature superheater; 7. Economizer; 9. Air preheater; 10. Secondary-reheat high-temperature reheater; 11. Secondary-reheat low-temperature reheater; 12. Burner; 13. Steam-water separator; 14. Water storage tank; 15. Recirculation pump; 16. First flue on the left; 17. Second flue on the left; 18. First flue on the right; 19. Second flue on the right. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0027] See also Figures 1 to 4As shown, an embodiment of the present application provides a tangentially fired secondary reheat T-type boiler, which includes a furnace 1 and two horizontal flues and two tail vertical flues symmetrically arranged on the left and right, a partition screen superheater 2, two high-temperature superheaters 3, a primary reheat high-temperature reheater 4, a primary reheat low-temperature reheater 5, two low-temperature superheaters 6, two economizers 7, two air preheaters 9, a secondary reheat high-temperature reheater 10, a secondary reheat low-temperature reheater 11, a burner 12, a steam-water separator 13, a water storage tank 14 and a recirculation pump 15.

[0028] See also Figure 3 The furnace 1 and the two horizontal flues and two tail vertical flues arranged symmetrically on the left and right form a T-shaped structure. The furnace 1 is surrounded by water-cooled walls, which include connected spiral tube ring water-cooled walls and vertical tube ring water-cooled walls. The upper parts of the water-cooled walls on both sides of the furnace 1 are bent to form two left and right flame bending angles; the two horizontal flues are respectively connected to the left and right flue gas outlets of the furnace 1, and are respectively recorded as the left horizontal flue and the right horizontal flue; the two tail vertical flues are respectively arranged on the left and right sides of the furnace 1, and are respectively recorded as the left tail vertical flue and the right tail vertical flue. The left rear vertical flue is connected to the left horizontal flue, and the right rear vertical flue is connected to the right horizontal flue. Both the left and right rear vertical flues are double flues. The left rear vertical flue includes a left first flue 16 and a left second flue 17. A tail flue damper 8 is arranged at the bottom of the double flues of the left rear vertical flue to regulate the flue gas flow of the two flues. The right rear vertical flue includes a right first flue 18 and a right second flue 19. A tail flue damper 8 is arranged at the bottom of the double flue of the right rear vertical flue to regulate the flue gas flow of the two flues. The primary reheat high-temperature reheater 4 and primary reheat low-temperature reheater 5 in the left flue and the secondary reheat high-temperature reheater 10 and secondary reheat low-temperature reheater 11 in the right flue use the tail flue damper 8 as the main temperature control method, and the burner swing is used as an auxiliary temperature control method.

[0029] See also Figure 1The partition screen superheater 2 is installed in the upper furnace radiation zone and is symmetrically arranged in the center between the two flue gas outlets of the furnace. The partition screen superheater 2 is composed of a large screen composed of multiple small screens; a high-temperature superheater 3 and a primary reheating high-temperature reheater 4 are arranged in sequence along the flue gas flow direction in the left horizontal flue; a high-temperature superheater 3 and a secondary reheating high-temperature reheater 10 are arranged in sequence along the flue gas flow direction in the right horizontal flue; the two high-temperature superheaters 3 are respectively arranged at the left and right flame bending angles of the upper part of the furnace 1; a primary reheating low-temperature reheater is arranged in the left tail vertical flue 5, low-temperature superheater 6, and economizer 7; the primary reheat low-temperature reheater 5 is arranged in the left flue 16, and the low-temperature superheater 6 and economizer 7 are arranged in sequence along the flue gas flow direction in the left second flue 17; the secondary reheat low-temperature reheater 11, low-temperature superheater 6, and economizer 7 are arranged in the right rear vertical flue; the secondary reheat low-temperature reheater 11 is arranged in the right flue 18, and the low-temperature superheater 6 and economizer 7 are arranged in sequence along the flue gas flow direction in the right second flue 19; an air preheater 9 is arranged at the outlet of each of the left and right rear vertical flues. The partition screen superheater 2, high-temperature superheater 3, and low-temperature superheater 6 are temperature-controlled using a coal-water ratio and a desuperheater.

[0030] In this embodiment, the boiler adopts a T-shaped layout, placing both the primary and secondary high-temperature reheaters in close proximity to the high-temperature superheater at the furnace outlet. This increases the heat transfer temperature difference, helps maintain the rated steam temperature, enhances the thermostatic performance of the secondary reheat boiler, and creates conditions for further improving steam parameters. During operation, the primary reheat steam temperature is adjusted by the left rear flue gas damper, while the secondary reheat steam temperature is adjusted by the right rear flue gas damper. The combined adjustment of the left and right rear flue gas dampers adjusts the heat distribution between the superheater, primary reheat, and secondary reheat, thereby achieving reheat steam temperature regulation over a wide load range. Burner swing serves as a supplementary thermostatic control measure, helping to adjust steam temperature in situations such as those caused by changes in coal quality.

[0031] See also Figure 2 and Figure 4, the burner 12 is installed on the furnace wall of the furnace 1, and the burner 12 is a direct current burner, which adopts a single-tangential circle or double-tangential circle combustion mode; the steam-water separator 13, the water storage tank 14 and the recirculation pump 15 are installed on one side of the outside of the furnace 1, the water outlet of the steam-water separator 13 is connected to the water inlet of the water storage tank 14, the water outlet of the water storage tank 14 is connected to the water inlet of the recirculation pump 15, the water outlet of the recirculation pump 15 is respectively connected to the water inlets of the two economizers 7, the water outlets of the two economizers 7 are connected to the water inlet of the water-cooled wall of the furnace 1, the water outlet of the water-cooled wall of the furnace 1 is connected to the water inlet of the steam-water separator 13, the steam outlet of the steam-water separator 13 is respectively connected to the steam inlets of the two low-temperature superheaters 6, and the steam outlets of the two low-temperature superheaters 6 are respectively connected to At the steam inlet of the partition screen superheater 2, the steam outlet of the partition screen superheater 2 is connected to the steam inlets of the two high-temperature superheaters 3 respectively, the steam outlets of the two high-temperature superheaters 3 are respectively connected to the steam inlet of the high-pressure cylinder of the steam turbine, the steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the primary reheat low-temperature reheater 5, the steam outlet of the primary reheat low-temperature reheater 5 is connected to the steam inlet of the primary reheat high-temperature reheater 4, the steam outlet of the primary reheat high-temperature reheater 4 is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine, the steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the secondary reheat low-temperature reheater 11, the steam outlet of the secondary reheat low-temperature reheater 11 is connected to the steam inlet of the secondary reheat high-temperature reheater 10, and the steam outlet of the secondary reheat high-temperature reheater 10 is connected to the steam inlet of the low-pressure cylinder of the steam turbine.

[0032] In this embodiment, boiler feedwater enters the water-cooled walls of the furnace 1 through economizers 7 in the left and right vertical flues for heat exchange. The heat exchange medium then flows through the spiral and vertical tube coil water-cooled walls and enters the steam-water separator 13. After separation in the steam-water separator 13, the steam passes through two low-temperature superheaters 6, two high-temperature superheaters 3, and the separator superheater 2, before being delivered to the high-pressure cylinder of the steam turbine via the main steam line to perform work. Exhaust steam from the high-pressure cylinder of the steam turbine passes through the primary reheat low-temperature reheater 5 and the primary reheat high-temperature reheater 4 in the left flue of the boiler before being delivered to the intermediate-pressure cylinder of the steam turbine to perform work. Exhaust steam from the intermediate-pressure cylinder passes through the secondary reheat low-temperature reheater 11 and the secondary reheat high-temperature reheater 10 in the right flue of the boiler before being delivered to the low-pressure cylinder of the steam turbine to perform work.

[0033] In this embodiment, the boiler adopts a starting system with a recirculation pump. At the initial start-up stage, the water separated by the steam-water separator enters the water storage tank, and is then pressurized by the recirculation pump and sent back to the water supply pipe, forming a recirculation operation mode. When the DC load is reached, the recirculation pump and its recirculation pipeline stop running.

[0034] In this embodiment, the boiler capacity is 600MW-1300MW, and the outlet steam temperature of the superheater, the primary reheater, and the secondary reheater is 600°C-720°C.

[0035] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A tangentially fired, double-reheat T-type boiler, characterized by: The T-shaped boiler comprises a furnace (1), a left horizontal flue, a right horizontal flue, a left rear vertical flue, a right rear vertical flue, a partition screen superheater (2), two high-temperature superheaters (3), a primary reheat high-temperature reheater (4), a primary reheat low-temperature reheater (5), two low-temperature superheaters (6), two economizers (7), two air preheaters (9), a secondary reheat high-temperature reheater (10), a secondary reheat low-temperature reheater (11) and a burner (12); The left horizontal flue and the right horizontal flue are respectively connected to the left and right flue gas outlets of the furnace (1); the left tail vertical flue is connected to the left horizontal flue, and the right tail vertical flue is connected to the right horizontal flue; the partition screen superheater (2) is installed above the furnace (1), and the burner (12) is installed on the outer wall of the furnace (1); a high-temperature superheater (3) and a primary reheat high-temperature reheater (4) are arranged in sequence in the left horizontal flue along the direction of flue gas flow; the right water A high-temperature superheater (3) and a secondary reheat high-temperature reheater (10) are arranged in sequence in the flue gas flow direction; a primary reheat low-temperature reheater (5), a low-temperature superheater (6) and an economizer (7) are arranged in the left tail vertical flue; a secondary reheat low-temperature reheater (11), a low-temperature superheater (6) and an economizer (7) are arranged in the right tail vertical flue; the two air preheaters (9) are arranged at the tail of the left tail vertical flue and the tail of the right tail vertical flue respectively; The T-type boiler further comprises a steam-water separator (13), a water storage tank (14) and a recirculation pump (15); the steam-water separator (13), the water storage tank (14) and the recirculation pump (15) are installed on one side outside the furnace (1); the water outlet of the steam-water separator (13) is connected to the water inlet of the water storage tank (14), the water outlet of the water storage tank (14) is connected to the water inlet of the recirculation pump (15), the water outlet of the recirculation pump (15) is respectively connected to the water inlets of two economizers (7), the water outlets of the two economizers (7) are connected to the water inlet of the water-cooled wall of the furnace (1), the water outlet of the water-cooled wall of the furnace (1) is connected to the water inlet of the steam-water separator (13), the steam outlet of the steam-water separator (13) is respectively connected to the steam inlets of two low-temperature superheaters (6), the steam outlets of the two low-temperature superheaters (6) are respectively connected to the water inlets of the separator (13), and the steam outlets of the two low-temperature superheaters (6) are respectively connected to the water inlets of the separator (13). The steam inlet of the partition screen superheater (2) and the steam outlet of the partition screen superheater (2) are respectively connected to the steam inlets of the two high temperature superheaters (3), the steam outlets of the two high temperature superheaters (3) are respectively connected to the steam inlet of the high pressure cylinder of the steam turbine, the steam outlet of the high pressure cylinder of the steam turbine is connected to the steam inlet of the primary reheat low temperature reheater (5), the steam outlet of the primary reheat low temperature reheater (5) is connected to the steam inlet of the primary reheat high temperature reheater (4). The steam inlet of the primary reheat high-temperature reheater (4) is connected to the steam inlet of the intermediate pressure cylinder of the steam turbine, the steam outlet of the intermediate pressure cylinder of the steam turbine is connected to the steam inlet of the secondary reheat low-temperature reheater (11), the steam outlet of the secondary reheat low-temperature reheater (11) is connected to the steam inlet of the secondary reheat high-temperature reheater (10), and the steam outlet of the secondary reheat high-temperature reheater (10) is connected to the steam inlet of the low-pressure cylinder of the steam turbine.

2. The tangentially fired double reheat T-type boiler according to claim 1, characterized in that: The furnace (1) is surrounded by water-cooled walls, which include interconnected spiral tube ring water-cooled walls and vertical tube ring water-cooled walls. The upper parts of the water-cooled walls on both sides of the furnace (1) are bent to form two left and right flame-folding angles; the two high-temperature superheaters (3) are respectively arranged at the left and right flame-folding angles on the upper part of the furnace (1).

3. The tangentially fired double reheat T-type boiler according to claim 1, characterized in that: The partition screen superheater (2) is arranged in the radiation zone of the furnace (1) and is arranged symmetrically in the center.

4. The tangentially fired double reheat T-type boiler according to claim 1, characterized in that: The left tail vertical flue and the right tail vertical flue are both double flue structures. The left tail vertical flue includes a left first flue (16) and a left second flue (17). The primary reheat low-temperature reheater (5) is arranged in the left first flue (16). The low-temperature superheater (6) and the economizer (7) are arranged in sequence in the left second flue (17) along the flue gas flow direction. The right tail vertical flue includes a right first flue (18) and a right second flue (19), the secondary reheating low-temperature reheater (11) is arranged in the right first flue (18), and the low-temperature superheater (6) and the economizer (7) are arranged in sequence in the right second flue (19) along the flue gas flow direction.

5. The tangentially fired double reheat T-type boiler according to claim 4, characterized in that: A tail smoke damper (8) is respectively arranged at the bottom of the double flue of the left tail vertical flue and the bottom of the double flue of the right tail vertical flue.

6. The tangentially fired double reheat T-type boiler according to claim 1, characterized in that: The burner (12) is a direct current burner and adopts a single tangential circle or double tangential circle combustion mode.

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