Biomass energy-saving boiler

Abstract

The utility model relates to the technical field of boiler, specifically disclose a kind of biomass energy-saving boiler. Including hearth, the bottom of hearth is equipped with fire grate, the side above hearth is equipped with the convection heat exchanger communicated with it, the convection heat exchanger is equipped with upper drum above, lower drum below, the side far away from hearth is equipped with flue gas outlet, the bottom of lower drum is equipped with fly ash precipitation bin communicated with convection heat exchanger, the bottom of fly ash precipitation bin is connected with secondary air main pipe, one end of secondary air main pipe is connected with secondary fan, the other end is communicated with the side wall of hearth. The present scheme realizes the multiplex function of " air supply + dust supply" by secondary air main pipe, secondary air is blown into hearth to stir flame, so that combustion is more sufficient, while, the unburnt carbon particles that settle are directly injected into main combustion zone and re-burned, which recovers carbon particles latent heat, reduces flue gas temperature, reduces fly ash and bottom ash carbon content, improves fuel utilization rate and boiler thermal efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of boilers, and specifically discloses a biomass energy-saving boiler. Background Technology

[0002] The typical structure of a biomass chain grate boiler is as follows: fuel falls from the hopper to the front end of the chain grate and moves backward with the grate; primary air passes through each air chamber from below the grate surface upward through the fuel layer to provide the oxygen required for main combustion; secondary air nozzles are arranged on the side wall of the furnace about 1–2 m above the grate, and the high-speed jet enters the furnace tangentially or obliquely to agitate the flame, supplement oxygen, and prolong the residence time of combustible gas and fine particles in the furnace, thereby improving the combustion completion rate. The high-temperature flue gas generated by combustion carries residual carbon particles into the rear convection tube bundle to continue to release heat, and is finally discharged after dust removal.

[0003] However, actual operation revealed that the flue gas often carries a significant amount of unburned carbon particles when leaving the furnace. Heavier particles (>0.5mm) settle in the convection section and are collected in the ash hopper. Although they can be intermittently returned to the front of the grate for reburning via the ash discharge pipe, the amount of returned ash is small, the distribution is uneven, and the reburning rate is insufficient. Meanwhile, "medium" fly ash (0.1-0.5mm) accumulates in large quantities at the tail of the grate and is directly discharged as the grate moves, wasting a considerable amount of fuel combustibles. For example, in a pre-furnace biomass assembled chain grate boiler disclosed in patent CN218328115U, although an economizer and air preheater are connected sequentially at the rear of the flue to form a tail-end waste heat recovery system, the unburned carbon particles and other combustibles are still not fully utilized. The energy-saving boiler coal-fired device disclosed in patent CN101915417A has a second air inlet channel that is directly connected to the bottom of the furnace. Although it can play a certain role in combustion, the upward blowing of secondary air will increase the amount of dust in the exhaust gas and exacerbate the difficulty of dust removal from the exhaust gas. Utility Model Content

[0004] The purpose of this utility model is to overcome the shortcomings of the existing technology and provide a biomass energy-saving boiler.

[0005] This utility model discloses a biomass energy-saving boiler, which adopts the following technical solution: A biomass energy-saving boiler includes a furnace, a grate at the bottom of the furnace, a convection heat exchanger communicating with the furnace on one side above the furnace, an upper drum above the convection heat exchanger, a lower drum below the convection heat exchanger, and a flue gas outlet on the side away from the furnace. A fly ash settling bin communicating with the convection heat exchanger is located at the bottom of the lower drum. A secondary air duct is connected to the bottom of the fly ash settling bin. A secondary air fan is connected to one end of the secondary air duct, and the other end is connected to the side wall of the furnace.

[0006] Preferably, the fly ash settling bin is provided with an ash collection hopper at the bottom. Preferably, the ash collection hopper is connected to the secondary air main pipe by an ash discharge pipe, and the ash discharge pipe is equipped with an ash discharge valve.

[0007] Preferably, multiple ash collection hoppers are provided along the extension direction of the convection heat exchanger.

[0008] Preferably, the side wall of the furnace is provided with a secondary air inlet channel, which is inclined downward from the outside to the inside, and the main secondary air pipe is connected to the furnace through the secondary air inlet channel.

[0009] Preferably, the secondary air main pipe is connected to a position at 1 / 5 to 1 / 3 of the height of the furnace.

[0010] Preferably, the junction of the fly ash settling chamber and the lower boiler drum is located at 1 / 2 to 4 / 5 of the height of the furnace.

[0011] Preferably, the starting end of the grate is connected to a feeding hopper, and the end of the grate is connected to a slag discharge system.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: This biomass energy-saving boiler solution adds a fly ash settling bin at the bottom of the lower drum and utilizes the secondary air main pipe to achieve the reuse function of "air supply + ash supply". The secondary air is blown into the furnace to stir the flame and make the combustion more complete. At the same time, the settled unburned carbon particles are directly sprayed into the main combustion zone for re-burning. This not only recovers the latent heat of carbon particles, but also reduces the flue gas temperature, reduces the carbon content of fly ash and bottom ash, improves fuel utilization and boiler thermal efficiency, simplifies the system, saves space, and has the dual benefits of energy saving and emission reduction. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the biomass energy-saving boiler, including the furnace, in this embodiment.

[0014] Explanation of icon numbers: 1. Furnace; 11. Secondary air inlet channel; 12. Flue gas outlet; 2. Grate; 21. Feed hopper; 22. Slag discharge system; 3. Convection heat exchanger; 4. Upper drum; 5. Lower drum; 6. Fly ash settling bin; 61. Ash collection hopper; 62. Ash discharge valve; 7. Secondary air main pipe; 8. Secondary air fan. Detailed Implementation

[0015] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] The biomass energy-saving boiler in this embodiment refers to... Figure 1The furnace includes a furnace chamber 1, a grate 2 at the bottom of the furnace chamber 1, a convection heat exchanger 3 connected to the furnace chamber 1 on one side above it, an upper drum 4 above the convection heat exchanger 3, a lower drum 5 below the convection heat exchanger 3, and a flue gas outlet 12 on the side away from the furnace chamber 1. A fly ash settling chamber 6 connected to the convection heat exchanger 3 is located at the bottom of the lower drum 5. A secondary air duct 7 is connected to the bottom of the fly ash settling chamber 6. A secondary air fan 8 is connected to one end of the secondary air duct 7, and the other end is connected to the side wall of the furnace chamber 1. This design elevates the furnace 1, upper drum 4, convection heat exchanger 3, and lower drum 5. This elevation not only increases the residence time of combustibles in the furnace 1, resulting in more complete fuel combustion, but also incorporates a fly ash settling bin 6 connected to the secondary air main pipe 7 at the bottom of the raised lower drum 5. During operation, the secondary air main pipe 7 simultaneously performs the functions of "secondary air conveying" and "unburned particle conveying." The combustion air provided by the secondary air fan 8 forms a high-speed airflow within the pipe, directly carrying the unburned carbon particles collected in the fly ash settling bin 6 and injecting them into the main combustion zone of the furnace 1. This achieves integrated air-ash recombustion, thereby recovering and burning combustible carbon particles and other substances that were originally discharged with the slag. This further reduces the flue gas temperature and recovers the latent heat of the carbon particles, ensuring full utilization of the fuel's calorific value, reducing the carbon content of fly ash and bottom ash, and improving boiler energy efficiency.

[0017] As a preferred option, the fly ash settling bin 6 is equipped with an ash collection hopper 61 at its bottom. The ash collection hopper 61 can temporarily store and collect the settled ash particles, ensuring continuous and stable secondary air ash conveying, preventing unsettled fly ash from being directly carried away, and improving reburning efficiency.

[0018] As a preferred embodiment, an ash discharge pipe is provided between the ash collection hopper 61 and the secondary air main pipe 7, and an ash discharge valve 62 is provided on the ash discharge pipe. By opening and closing the ash discharge valve 62 and adjusting its opening degree, the amount of ash returned can be flexibly controlled according to the boiler load, so as to realize the online adjustable fly ash reburning ratio, which can both ensure complete combustion and prevent blockage of the secondary air system.

[0019] As a preferred option, multiple ash collection hoppers 61 are provided along the extension direction of the convection heat exchanger 3; the combination of the multi-point arrangement of ash collection hoppers 61 and ash discharge pipes enables the fly ash to be uniformly recovered and sent back in sections throughout the entire convection section, further improving the burnout rate and boiler load adaptability.

[0020] As a preferred embodiment, the side wall of the furnace 1 is provided with a secondary air inlet channel 11, which is inclined downward from the outside to the inside. The secondary air main pipe 7 is connected to the furnace 1 through the secondary air inlet channel 11. The inclined downward jet can form an agitated air curtain covering the firebed above the grate 2, prolonging the residence time of fly ash particles in the furnace. In addition, the inclined downward channel utilizes gravity to make it easier for unburned carbon particles to enter the furnace 1 smoothly with the secondary air, improving particle blockage and achieving immediate and continuous fly ash discharge, effectively improving the problem of untimely fly ash discharge.

[0021] As a preferred option, the secondary air main pipe 7 is connected to a position at 1 / 5 to 1 / 3 of the height of the furnace 1. This height avoids the secondary air jet kinetic energy being too high, causing fly ash to be blown instantaneously towards the furnace 1 outlet and shortening the combustion time, while also avoiding the secondary air penetrating the firebed, lowering the temperature of the main combustion zone of the grate 2, or stirring up the ash layer, causing excessive fly ash to be thrown up and making it difficult to burn completely. Thus, oxygen is supplemented and disturbance is enhanced in the optimal range, so as to achieve sufficient retention and efficient combustion of unburned carbon particles.

[0022] As a preferred option, the junction of the fly ash settling bin 6 and the lower boiler drum 5 is located at a height of 1 / 2 to 4 / 5 of the furnace 1. This range ensures that the junction is high enough to allow the flue gas to slow down sufficiently in the convection section and effectively collect fly ash by gravity settling, avoiding insufficient settling distance and reduced ash collection efficiency due to an excessively low junction. At the same time, it prevents the junction from being too high, which would force the interface between the secondary air duct 7 and the furnace 1 to move upward, exceeding the optimal height range and affecting the rigidity of the secondary air jet and the re-combustion effect of unburned carbon particles. Thus, it balances efficient settling with a reasonable ash delivery height.

[0023] As a preferred embodiment, the starting end of the grate 2 is connected to a charging hopper 21, and the end end of the grate 2 is connected to a slag removal system 22. The charging hopper 21 enables continuous and uniform feeding of biomass fuel, and the slag removal system 22 promptly discharges the burnt bottom ash. Together with the fly ash reburning system, a complete combustion process of "grate main combustion - fly ash reburning - slag and ash diversion" is formed, which further improves the boiler thermal efficiency and reduces the carbon content of the bottom ash.

[0024] The technical solution provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A biomass energy-saving boiler, characterized in that, The furnace includes a furnace chamber, a grate at the bottom of the furnace chamber, a convection heat exchanger connected to the grate on one side above the furnace chamber, an upper drum above the convection heat exchanger, a lower drum below the convection heat exchanger, and a flue gas outlet on the side away from the furnace chamber. A fly ash settling chamber connected to the convection heat exchanger is located at the bottom of the lower drum. A secondary air duct is connected to the bottom of the fly ash settling chamber. A secondary air duct is connected to a secondary fan at one end and to the side wall of the furnace chamber at the other end.

2. The biomass energy-saving boiler according to claim 1, characterized in that, The fly ash settling bin is equipped with an ash collection hopper at its bottom.

3. The biomass energy-saving boiler according to claim 2, characterized in that, The ash collection hopper is connected to the secondary air main pipe by an ash discharge pipe, and an ash discharge valve is provided on the ash discharge pipe.

4. The biomass energy-saving boiler according to claim 2, characterized in that, Multiple ash collection hoppers are provided along the extension direction of the convection heat exchanger.

5. The biomass energy-saving boiler according to claim 1, characterized in that, The side wall of the furnace is provided with a secondary air inlet channel, which is inclined downward from the outside to the inside. The main secondary air pipe is connected to the furnace through the secondary air inlet channel.

6. The biomass energy-saving boiler according to claim 1, characterized in that, The secondary air main pipe is connected to a position at 1 / 5 to 1 / 3 of the height of the furnace.

7. The biomass energy-saving boiler according to claim 1, characterized in that, The junction between the fly ash settling chamber and the lower boiler drum is located at 1 / 2 to 4 / 5 of the height of the furnace.

8. The biomass energy-saving boiler according to claim 1, characterized in that, The grate is connected to a feeding hopper at its starting end and to a slag discharge system at its ending end.

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