A high-power coal gas molten salt boiler structure

Abstract

The utility model discloses a kind of high-power gas molten salt boiler structure, including boiler main body, the boiler main body is L-shaped, into horizontal flue section and vertical heat exchange section, vertical heat exchange section is arranged with molten salt heat exchange system, molten salt heat exchange system includes multistage molten salt heat exchanger, multistage molten salt heat exchanger is sequentially arranged from below to above along flue gas flow direction, molten salt in multistage molten salt heat exchanger flows from top to bottom, and flue gas flows from bottom to top, forms counterflow heat exchange.The utility model integrates three-stage molten salt heat exchanger by L-shaped boiler body, using the characteristics of high heat storage density and stable working condition of molten salt, converts coal gas combustion waste heat into high-temperature molten salt storage, realizes "off-grid" heat storage and on-demand power generation;While vertical counterflow stratified layout and modularization serpentine pipe group are used, flue gas flow field distribution is optimized, system cold-state start time is shortened, flue gas resistance is reduced, and heat exchange efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of industrial waste heat utilization and energy storage technology, and in particular to a high-power coal gas molten salt boiler structure, which is suitable for coal gas waste heat recovery and thermal storage peak shaving power generation. Background Technology

[0002] Steel companies urgently need to address the energy waste and environmental pollution caused by blast furnace gas venting. Traditional gas utilization technologies have two major drawbacks: First, conventional gas boilers are limited by the "on-demand" model, making it impossible to store surplus gas heat energy and match peak-valley electricity price differences, resulting in steel plants losing over 100 million yuan in peak-shaving revenue annually. Second, existing molten salt thermal energy storage systems suffer from long start-up preheating times and high operating resistance due to their crude boiler structure design, redundant flue gas flow, and dense heat exchanger tube bundle arrangement, making them unsuitable for the demanding scenarios of large gas fluctuations and rapid peak-shaving response in steel plants.

[0003] Therefore, developing a high-power gas-fired molten salt boiler structure is of great significance for energy conservation, emission reduction, and sustainable development of steel and coal chemical enterprises. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model designs a high-power coal gas molten salt boiler structure, effectively solving the challenge of coordinating the utilization of coal gas resources and the flexible peak-shaving of the power grid in the steel industry, and providing a new approach for energy conservation and emission reduction in steel enterprises.

[0005] The present invention adopts the following technical solution:

[0006] A high-power gas-fired molten salt boiler structure includes a boiler body, which is L-shaped and divided into a horizontal flue section and a vertical heat exchange section. A molten salt heat exchange system is arranged in the vertical heat exchange section. The molten salt heat exchange system includes multi-stage molten salt heat exchangers, which are arranged sequentially from bottom to top along the flue gas flow direction. Molten salt flows from top to bottom in the multi-stage molten salt heat exchangers, forming counter-current heat exchange with the flue gas flowing from bottom to top.

[0007] Preferably, the molten salt heat exchange system includes a primary molten salt heat exchanger, a secondary molten salt heat exchanger, and a tertiary molten salt heat exchanger, wherein the flow heat exchange modes of the primary, secondary, and tertiary molten salt heat exchangers are cross-counterflow, cross-counterflow, and cross-co-flow, respectively.

[0008] Preferably, the horizontal flue section includes a combustion chamber and a horizontal flue, with a combustion system and equipment arranged at the end of the combustion chamber.

[0009] Preferably, the vertical heat exchange section includes a vertical flue and a tail chimney, with the horizontal flue seamlessly connected to the vertical flue.

[0010] Preferably, a water-cooled heat exchange system is arranged in the vertical heat exchange section, which includes a primary economizer and a secondary economizer.

[0011] Preferably, an air preheating system is arranged in the vertical heat exchange section, and the air preheating system includes an air preheater.

[0012] Preferably, the primary and secondary economizers each employ a carbon steel finned tube structure. They are primarily used to reduce flue gas temperature while simultaneously heating feedwater to supply the SGS system for gas generation; the air preheater preheats the combustion air to 300°C, improving combustion efficiency.

[0013] Preferably, all the multi-stage molten salt heat exchangers are of a smooth tube serpentine tube structure.

[0014] Preferably, the heat exchange tubes of the multi-stage molten salt heat exchanger are arranged at an inclined angle of 3-5°.

[0015] Preferably, the multi-stage molten salt heat exchanger is arranged in a cross-flow pattern with two separate channels in the depth direction of the flue.

[0016] The beneficial effects of this utility model are: (1) The three-stage molten salt heat exchanger is arranged vertically to gradually reduce the flue gas temperature gradient. Through the heat exchange method of counter-current and co-current, the gradient deep recovery of flue gas heat energy is achieved while ensuring the molten salt outlet temperature and improving the safety of the molten salt system operation; (2) The molten salt heat exchange and waste heat recovery module (economizer + air preheater) are coupled to form an integrated "main heat exchange - tail waste heat recovery". The hot water after the economizer heat exchange can be used for SGS system feedwater, and the high-temperature combustion air after the air preheater can improve the gas combustion efficiency. 8%-12%; (3) To address the pain point of coke oven / blast furnace gas release rate in steel enterprises, the released gas is utilized as a resource. Combined with molten salt energy storage technology, the system has a continuous energy release capacity of 6-8 hours, increasing the peak shaving capacity of steel enterprises and coal chemical industry; (4) Compact anti-condensation structure design, L-shaped three-dimensional layout reduces the floor area by 40% compared with traditional horizontal boilers, vertical molten salt tube bundle adopts serpentine tube bundle inclined arrangement to avoid the risk of molten salt freezing, and at the same time, in the furnace depth direction, it is arranged in front and rear double flow cross arrangement, which greatly saves furnace height space. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] In the diagram: 1. Combustion system and equipment, 2. Combustion chamber and horizontal flue, 3. Vertical flue, 4. Primary molten salt heat exchanger, 5. Secondary molten salt heat exchanger, 6. Tertiary molten salt heat exchanger, 7. Primary economizer, 8. Air preheating system, 9. Secondary economizer, 10. Tail chimney. Detailed Implementation

[0019] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0020] Example: Figure 1 As shown, a high-power gas-fired molten salt boiler structure includes a combustion system and equipment 1, a combustion chamber and horizontal flue 2, a molten salt heat exchange system, a water-cooled heat exchange system, and an air preheating system 8. The combustion system and equipment 1 is installed at the end of the horizontal flue 2 of the L-shaped boiler body. The molten salt heat exchange system, the water-cooled heat exchange system, and the air preheating system are installed on the vertical flue 3 of the L-shaped boiler body. A tail chimney 10 is installed at the tail end of the vertical flue 3 of the boiler. The molten salt heat exchange system includes a primary molten salt heat exchanger 4, a secondary molten salt heat exchanger 5, and a tertiary molten salt heat exchanger 6. The water-cooled heat exchange system includes a primary economizer 7 and a secondary economizer 9. The air preheating system 8 includes a tubular air preheater and external hot and cold air ducts for the boiler.

[0021] In a molten salt heat exchange system, each stage of the heat exchanger consists of three parts: an inlet header, a serpentine tube hot surface, and an outlet header. The inlet header of the first-stage molten salt heat exchanger is connected to the outlet header of the second-stage molten salt heat exchanger via a pipeline, and the outlet header of the third-stage molten salt heat exchanger is connected to the inlet header of the second-stage molten salt heat exchanger via a pipeline. In a water-cooled heat exchange system, the two-stage economizer consists of an inlet header, a finned tube hot surface, and an outlet header. The outlet header of the second-stage economizer is connected to the inlet header of the first-stage economizer via a pipeline. In an air preheating system, the air preheater is connected upstream to a cold air duct and a fan, and downstream to combustion equipment via a hot air duct.

[0022] The operation method of this high-power gas-fired molten salt boiler structure includes the following steps:

[0023] S1. Industrial gas enters the horizontal combustion chamber of the boiler through the combustion system for combustion. The high-temperature flue gas generated by combustion enters the vertical flue after turning, and then flows through the serpentine tube hot surfaces of the primary molten salt heat exchanger, the secondary molten salt heat exchanger, and the tertiary molten salt heat exchanger in sequence. After the temperature decreases, it is further heat-exchanged by the hot surfaces of the primary economizer, the air preheater, and the secondary economizer, and the temperature decreases to about 120°C before being discharged through the chimney.

[0024] S2. The molten salt uses a binary salt, drawn from the cold salt tank by a molten salt pump. It is then piped into the two inlet headers of the tertiary molten salt heat exchanger, where it is distributed to the hot face tubes for heat exchange with the flue gas. The molten salt, after heat exchange, is collected in the outlet header of the tertiary molten salt heat exchanger and then enters the inlet header of the secondary molten salt heat exchanger via connecting pipes. After heat exchange on the hot face tubes of the secondary molten salt heat exchanger, it enters the outlet header. The molten salt flow direction in the tertiary and secondary molten salt heat exchangers is arranged in a cross-counterflow manner with the flue gas flow direction. After mixing in the outlet header of the secondary molten salt heat exchanger, the molten salt is introduced into the lower inlet header of the primary molten salt heat exchanger via connecting pipes. It then exchanges heat with the flue gas in a cross-co-flow manner through the hot face tubes to prevent overheating. Finally, the molten salt is heated to 560°C and enters the outlet header, from where it is stored in the hot salt tank via pipelines.

[0025] S3. Cooling water is pressurized by a water pump and cooled by the flue gas through the secondary economizer and the primary economizer. The heated water can enter the plant's hot water circulation system or be stored in a hot water tank. It will enter the SGS system to produce steam during the heat release stage of the molten salt thermal storage system. Cold air is introduced into the air preheater by a fan through a cold air duct for heat exchange. The hot air after heat exchange is introduced into the combustion system through a hot air duct to supply oxygen for gas combustion.

[0026] S4. Cold salt and heated molten salt are stored in a conventional molten salt energy storage system and equipped with a corresponding SGS system. During peak electricity consumption in the plant area, the molten salt in the hot salt tank enters the SGS system to generate steam for power generation.

[0027] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A high-power coal gas molten salt boiler structure comprising a boiler main body, characterized in that, The boiler body is L-shaped and is divided into a horizontal flue section and a vertical heat exchange section. The vertical heat exchange section is equipped with a molten salt heat exchange system, which includes a multi-stage molten salt heat exchanger. The multi-stage molten salt heat exchanger is arranged sequentially from bottom to top along the flue gas flow direction. The molten salt in the multi-stage molten salt heat exchanger flows from top to bottom, forming a counter-current heat exchange with the flue gas flowing from bottom to top.

2. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, The molten salt heat exchange system includes a primary molten salt heat exchanger, a secondary molten salt heat exchanger, and a tertiary molten salt heat exchanger. The flow heat exchange modes of the primary, secondary, and tertiary molten salt heat exchangers are cross-counterflow, cross-counterflow, and cross-co-flow, respectively.

3. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, The horizontal flue section includes a combustion chamber and a horizontal flue, with a combustion system and equipment arranged at the end of the combustion chamber.

4. A high-power coal gas molten-salt boiler structure according to claim 3, characterized in that, The vertical heat exchange section includes a vertical flue and a tail chimney, with the horizontal flue seamlessly connected to the vertical flue.

5. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, The vertical heat exchange section is equipped with a water-cooled heat exchange system, which includes a primary economizer and a secondary economizer.

6. The structure of a high-power gas-fired molten salt boiler according to claim 1, characterized in that, An air preheating system is arranged within the vertical heat exchange section, and the air preheating system includes an air preheater.

7. A high-power coal gas molten-salt boiler structure according to claim 5, characterized in that, The primary economizer and the secondary economizer both adopt carbon steel finned tube structures.

8. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, All the multi-stage molten salt heat exchangers are of the bare tube serpentine tube structure.

9. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, The heat exchange tubes of the multi-stage molten salt heat exchanger are arranged at an inclined angle of 3-5°.

10. A high-power coal gas molten-salt boiler structure according to claim 1, characterized in that, The multi-stage molten salt heat exchangers are arranged in a cross-flow pattern with two separate channels along the depth of the flue.

Images