A full-hydrophobic baffle temperature-regulating subcritical low-calorific-value coal gas boiler

Abstract

The application discloses a full-hydrophobic baffle temperature-regulating subcritical low-calorific-value coal gas-fired boiler, the lower part of the water-cooled wall is a low-calorific-value coal gas combustion zone, the upper part is a variable cross-section heating surface arrangement zone, low-temperature superheaters and low-temperature reheaters are arranged in the front and rear flues of the wall respectively, and flue gas baffles are arranged at the outlets of the two to regulate the temperature. The lower part of the wall is sequentially connected with a high-temperature economizer, a denitration device and a low-temperature economizer for hierarchical arrangement. The heating surfaces such as the low-temperature superheater and the screen-type superheater are horizontally arranged. The application utilizes the baffle temperature regulation to improve the heat transfer efficiency and fuel utilization rate; the hierarchical economizers guarantee the full-load denitration of the boiler and meet the requirement of the flue gas temperature; and the horizontally arranged heating surfaces realize full hydrophobicity, effectively preventing the accumulation of oxide scales.

Description

Technical Field

[0001] This application belongs to the field of boiler technology, and in particular relates to a subcritical boiler using low-calorific-value coal gas with a fully hydrophobic baffle temperature regulation system. Background Technology

[0002] The efficient use of energy has always been a key concern in the energy sector, and improving boiler steam parameters is currently an effective method. A subcritical unit with a main steam pressure of 17.5 MPa, superheated steam temperature of 571℃, and reheat steam temperature of 569℃ can achieve a calculated efficiency of ~40%, and its gas consumption for power generation is reduced by 0.2 Nm³ compared to ultra-high pressure parameter units. 3 / kw.h.

[0003] Currently, steel mills use a high proportion of low-calorific-value gas in their coal combustion, which has a low theoretical combustion temperature and weak flue gas radiation capacity. This poses a challenge to boilers in simultaneously meeting the temperature requirements of both main steam and reheat steam. Existing technologies often use flue gas recirculation for temperature regulation, but this reduces the flue gas temperature at the furnace outlet, weakens the flue gas radiation capacity, and limits fuel utilization.

[0004] Meanwhile, due to various limitations such as production operation and technology, the load of gas boilers fluctuates greatly and operating conditions change frequently, often operating at low loads year-round. Under these low-load operating conditions, conventional economizer arrangements often result in excessively low flue gas temperatures, failing to meet the temperature window requirements of the denitrification unit and making full-load denitrification difficult. Furthermore, the existing boiler heating surface arrangement makes it difficult to achieve complete drainage during shutdown, easily leading to oxide scale buildup inside the tubes and affecting the safe operation of the unit.

[0005] Therefore, in order to meet the load and fuel demand of steel enterprises, a subcritical boiler with low calorific value coal gas and full hydrophobic baffle temperature regulation is proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low calorific value of coal gas, low combustion temperature, weak radiation capacity, large load variation of unit, and low operating load of unit, and to provide a subcritical subcritical boiler for burning low calorific value coal gas with full condensate baffle temperature regulation.

[0007] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: This application provides a subcritical low-calorific-value gas-fired boiler with fully hydrophobic baffle temperature regulation, including a water-cooled wall, wall enclosure, roof tubes, low-temperature superheater, screen-type superheater, three-stage superheater, final-stage superheater, low-temperature reheater, final-stage reheater, steam drum, flue gas baffle, high-temperature economizer, denitrification device, low-temperature economizer, and tubular air preheater. The furnace is equipped with water-cooled walls and a casing wall. A high-temperature economizer is installed at the bottom of the casing wall. A denitrification device is connected to the bottom of the high-temperature economizer. A low-temperature economizer is connected to the bottom of the denitrification device. A tubular air preheater is connected to the bottom of the low-temperature economizer. The high-temperature economizer is connected to the steam drum. The steam drum is connected to the roof tubes and the water-cooled walls. A low-temperature superheater is arranged in the front flue of the casing wall. The low-temperature superheater is connected to the screen superheater. The screen superheater is connected to the tertiary superheater. The tertiary superheater is connected to the final superheater. A low-temperature reheater is arranged in the rear flue of the casing wall. The low-temperature reheater is connected to the final reheater.

[0008] Optionally, the lower part of the water-cooled wall is a low-calorific-value gas combustion zone, and the upper part is a variable cross-section heating surface arrangement zone.

[0009] Optionally, the screen-type superheater is arranged at the furnace outlet, the three-stage superheater is connected to a collection box, and the final-stage superheater is connected to a collection box.

[0010] Optionally, a first-stage desuperheater is provided between the screen-type superheater and the three-stage superheater, and a second-stage desuperheater is provided between the three-stage superheater and the final-stage superheater. The heating surfaces of the low-temperature superheater, the screen-type superheater, the three-stage superheater, and the final-stage superheater are all arranged horizontally.

[0011] Optionally, flue gas baffles are provided at the flue gas outlets of both the low-temperature superheater and the low-temperature reheater.

[0012] Optionally, the screen-type superheater has a hanging pipe, which hangs the tube-screen portion of the screen-type superheater, the three-stage superheater, the final-stage superheater, and the final-stage reheater.

[0013] Compared with the prior art, the beneficial effects of the embodiments of this application are: (1) The temperature is adjusted by baffle between the low-temperature superheater and the low-temperature reheater. The load adaptability is wide. Compared with the flue gas recirculation temperature adjustment, the flue gas temperature at the furnace outlet is higher and the flue gas radiation capacity is stronger, which improves the heat transfer efficiency and thus improves the fuel utilization rate.

[0014] (2) The economizer is set in stages, which can ensure that the boiler denitrification is carried out at full load and that the boiler flue gas temperature meets the requirements, thereby improving the overall efficiency of the boiler.

[0015] (3) The heating surface is arranged horizontally, which can achieve complete hydrophobicity and prevent the accumulation of oxide scale. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a subcritical boiler using low-calorific-value coal gas with a fully hydrophobic baffle for temperature regulation, according to the present invention.

[0018] Illustration: 1. Water-cooled wall; 2. Wall enclosure; 3. Roof tube; 4. Low-temperature superheater; 5. Screen-type superheater; 6. Three-stage superheater; 7. Final stage superheater; 8. Low-temperature reheater; 9. Final stage reheater; 10. Steam drum; 11. Flue gas damper; 12. High-temperature economizer; 13. Denitrification device; 14. Low-temperature economizer; 15. Tubular air preheater. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0023] like Figure 1 As shown, it includes a water-cooled wall 1, a wall enclosure 2, a roof tube 3, a low-temperature superheater 4, a screen-type superheater 5, a three-stage superheater 6, a final-stage superheater 7, a low-temperature reheater 8, a final-stage reheater 9, a steam drum 10, a flue gas damper 11, a high-temperature economizer 12, a denitrification device 13, a low-temperature economizer 14, and a tubular air preheater 15.

[0024] The furnace is equipped with a water-cooled wall 1 and a casing wall 2. A high-temperature economizer 12 is installed at the lower part of the casing wall 2. The economizer is staged to ensure both full-load denitrification of the boiler and that the boiler exhaust temperature meets requirements. A denitrification device 13 is connected to the lower part of the high-temperature economizer 12, and a low-temperature economizer 14 is connected to the lower part of the denitrification device 13. A tubular air preheater 15 is connected to the lower part of the low-temperature economizer 14. The high-temperature economizer 12 is connected to the steam drum 10. The steam drum 10 is connected to... The ceiling tube 3 is connected to the water-cooled wall 1. The front flue of the wall enclosure 2 is equipped with a low-temperature superheater 4. The superheater adopts a four-stage arrangement, with small enthalpy increase in each stage, uniform heat absorption, and small deviation. The low-temperature superheater 1 is connected to the screen-type superheater 5. The screen-type superheater 5 is connected to the three-stage superheater 6. The three-stage superheater 6 is connected to the final stage superheater 7. The rear flue of the wall enclosure 2 is equipped with a low-temperature reheater 8. The low-temperature reheater 8 is connected to the final stage reheater 9.

[0025] The flue gas damper 11 is located at the outlets of the low-temperature superheater 4 and the low-temperature reheater 8. When the reheat steam temperature changes, the opening degree of the flue gas damper is adjusted to regulate the reheat steam temperature. For example, by adjusting the opening ratio of the flue gas damper 11 at the outlets of the low-temperature superheater 4 in the front flue and the low-temperature reheater 8 in the rear flue, the distribution of flue gas flow through the front and rear flues is changed, thereby changing the heat absorption ratio of the superheater and the reheater, and thus achieving the regulation of the reheat steam temperature.

[0026] The lower part of the water-cooled wall 1 is the combustion zone for low-calorific-value gas, and the upper part is the area for the arrangement of variable cross-section heating surfaces. The lower water-cooled wall is designed to ensure that the heat load of gas combustion is within the control range, while the upper water-cooled wall with variable cross-section is designed to ensure that the heat transfer efficiency is higher after the combustion of gas with low calorific value and weak radiation capacity.

[0027] A first-stage desuperheater is installed between the screen-type superheater 5 and the three-stage superheater 6, and a second-stage desuperheater is installed between the three-stage superheater 6 and the final-stage superheater 7. The low-temperature superheater 4, the screen-type superheater 5, the three-stage superheater 6 and the final-stage superheater 7 are arranged in four stages. The enthalpy increase of each stage heating surface is small and the thermal deviation is small. The heating surfaces are all arranged horizontally to ensure complete drainage.

[0028] Furthermore, to ensure uniform mixing and distribution of the working fluid among the various heating surfaces, the three-stage superheater 6 and the final-stage superheater 7 are connected to a collection box. The superheaters at each stage are connected via these collection boxes. This collection box structure, combined with the horizontal arrangement of the heating surfaces, allows water accumulated in the pipes to flow smoothly into the collection box and be completely drained when the boiler is shut down and drained. This avoids the localized water accumulation dead zones that are easily caused in traditional structures, achieving truly complete drainage and effectively preventing oxide scale buildup inside the pipes, thus ensuring the safe operation of the unit.

[0029] The screen-type superheater 5 is arranged at the furnace outlet, which is the heating surface that receives both direct radiant heat from the furnace and convective heat from the flue gas.

[0030] In some other embodiments of this application, the hanging tubes of the screen-type superheater 5 suspend the tube-screen parts of the screen-type superheater 5, the final stage superheater 7, the final stage reheater 9, and the tertiary superheater 6, which can simplify the support structure, save space and materials, and avoid mutual compression and pulling deformation of the tube screens.

[0031] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A subcritical boiler using low-calorific-value coal gas with a fully hydrophobic baffle temperature control system, characterized in that, It includes water-cooled walls (1), wall coverings (2), roof tubes (3), low-temperature superheaters (4), screen-type superheaters (5), three-stage superheaters (6), final-stage superheaters (7), low-temperature reheaters (8), final-stage reheaters (9), steam drums (10), flue gas baffles (11), high-temperature economizers (12), denitrification devices (13), low-temperature economizers (14), and tubular air preheaters (15). The furnace is equipped with a water-cooled wall (1) and a casing wall (2). A high-temperature economizer (12) is installed at the bottom of the casing wall (2). A denitrification device (13) is connected to the bottom of the high-temperature economizer (12). A low-temperature economizer (14) is connected to the bottom of the denitrification device (13). A tubular air preheater (15) is connected to the bottom of the low-temperature economizer (14). The high-temperature economizer (12) is connected to the steam drum (10). The steam drum (10) is connected to the roof tube (3) and the water-cooled wall (1). A low-temperature superheater (4) is arranged in the front flue of the casing wall (2). The low-temperature superheater (4) is connected to the screen superheater (5). The screen superheater (5) is connected to the three-stage superheater (6). The three-stage superheater (6) is connected to the final stage superheater (7). A low-temperature reheater (8) is arranged in the rear flue of the casing wall (2). The low-temperature reheater (8) is connected to the final stage reheater (9).

2. The subcritical low-calorific-value gas-fired boiler with fully hydrophobic baffles for temperature regulation according to claim 1, characterized in that: The lower part of the water-cooled wall (1) is a low-calorific-value gas combustion zone, and the upper part is a variable cross-section heating surface arrangement zone.

3. A subcritical subcritical boiler using low-calorific-value coal gas with a fully hydrophobic baffle temperature control according to claim 2, characterized in that: The screen-type superheater (5) is arranged at the furnace outlet, the three-stage superheater (6) is connected to a collection box, and the final stage superheater (7) is connected to a collection box.

4. A subcritical low-calorific-value gas-fired boiler with a fully hydrophobic baffle for temperature regulation according to claim 3, characterized in that: A first-stage desuperheater is provided between the screen-type superheater (5) and the third-stage superheater (6), and a second-stage desuperheater is provided between the third-stage superheater (6) and the final-stage superheater (7). The heating surfaces of the low-temperature superheater (4), the screen-type superheater (5), the third-stage superheater (6) and the final-stage superheater (7) are all arranged horizontally.

5. A subcritical low-calorific-value coal gas boiler with a fully hydrophobic baffle temperature control system according to claim 1, characterized in that: The flue gas outlets of the low-temperature superheater (4) and the low-temperature reheater (8) are both equipped with flue gas baffles (11).

6. A subcritical subcritical boiler using low-calorific-value coal gas with a fully hydrophobic baffle as described in claim 1, characterized in that: The screen-type superheater (5) has a hanging pipe, which hangs the tube screen portion of the screen-type superheater (5), the three-stage superheater (6), the final stage superheater (7) and the final stage reheater (9).

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