Organic heat carrier boiler for burning crop straw

Abstract

The utility model relates to the technical field of boiler, concretely is a kind of to burn crop straw organic heat carrier boiler, including upper furnace body, the lower part of upper furnace body is equipped with lower furnace body, the bottom of lower furnace body is equipped with foundation, the inside of upper furnace body is provided with the heat exchange pipe of serpentine arrangement, the inside of lower furnace body is provided with combustion chamber, the bottom of combustion chamber is equipped with fire grate, the upper portion inner wall of combustion chamber is equipped with air inlet pipe, and one end of air inlet pipe is provided with air inlet, one end of upper furnace body is connected with flue, and the outer end of flue is sequentially connected with waste heat steam boiler, air preheater, and the other end of upper furnace body is connected with feeding hopper.In the crop straw organic heat carrier boiler of burning, the utility model is innovated to the structure of crop straw organic heat carrier boiler of burning, effectively improves the various technical limitations of existing straw boiler in practical application, and in the dimension such as heat energy utilization efficiency, environmental protection emission performance, equipment operation stability and operation and maintenance convenience, significant optimization is realized.

Description

Technical Field

[0001] This utility model relates to the field of boiler technology, specifically to a boiler that uses crop straw as an organic heat carrier. Background Technology

[0002] In industrial production, agricultural drying, and district heating, boilers, as core heat energy supply equipment, directly impact the sustainable development of industries through their energy consumption and environmental performance. Currently, most mainstream boilers rely on fossil fuels such as coal and natural gas. On the one hand, fossil fuels are non-renewable resources, and their reserves are continuously decreasing due to long-term extraction, leading to a year-on-year increase in fuel costs and placing a heavy economic burden on businesses. On the other hand, the combustion of fossil fuels releases large amounts of sulfur dioxide, nitrogen oxides, and particulate matter, exacerbating air pollution and significantly conflicting with my country's "dual-carbon" strategy and environmental protection regulations. Therefore, upgrading and replacing traditional fossil fuel boilers has become an inevitable trend in the industry.

[0003] In response to the call for renewable energy utilization, some companies have attempted to develop straw-burning boilers. However, existing technologies still face numerous bottlenecks, making it difficult to meet practical application needs. For example, the vertical biomass boiler disclosed in patent CN204574460U, although employing a double-walled structure for basic insulation, only uses horizontal and vertical pipes to form a simple heat exchange structure inside the boiler, without a flue gas guiding device. This results in a short flue gas flow path, insufficient heat exchange, and a thermal efficiency generally below 70%. The manufacturing process of the plant straw combustion boiler disclosed in patent CN104713067A only focuses on the basic structural design of feeding and slag removal. Its straight-tube heat exchange system lacks an effective heat recovery design, resulting in a heat loss rate of over 20%, which is insufficient to meet the requirements of organic heat carrier boilers for a stable high-temperature heat source of 300-350℃. Regarding ash and slag removal, although the straw bale biomass boiler disclosed in patent CN221944189U has improved the grate structure, it has not optimized the ash removal design of the heat exchange area. Its ash removal doors are insufficient in number and have an unreasonable layout, which makes it easy for ash and slag to clog the heat exchange gaps, requiring frequent shutdowns for cleaning, which seriously affects the stability of continuous operation. Utility Model Content

[0004] The purpose of this utility model is to provide a boiler that burns crop straw as an organic heat carrier, in order to solve the problem mentioned in the background art that although a double-layer furnace wall structure is used to achieve basic insulation, the furnace body only has a simple heat exchange structure formed by horizontal and vertical pipes, and no flue gas guiding device is set up, resulting in a short flue gas flow path and insufficient heat exchange.

[0005] To achieve the above objectives, this utility model provides a crop straw organic heat carrier boiler, comprising an upper furnace body, a lower furnace body installed at the lower part of the upper furnace body, a foundation installed at the bottom of the lower furnace body, heat exchange tubes arranged in a serpentine pattern inside the upper furnace body, a combustion chamber inside the lower furnace body, a grate installed at the bottom of the combustion chamber, an air inlet pipe installed on the upper inner wall of the combustion chamber, an air inlet at one end of the air inlet pipe, a flue connected to one end of the upper furnace body, a waste heat steam boiler and an air preheater sequentially connected to the outer end of the flue, and a feed hopper connected to the other end of the upper furnace body.

[0006] This setup employs a split structure of "upper furnace body + lower furnace body" to achieve functional zoning. The foundation at the bottom of the lower furnace body ensures the overall stability of the equipment. The internal combustion chamber and grate form the core area for straw combustion. The upper inner wall air inlet pipe (with air inlet) can supplement secondary air to promote more complete straw combustion. The serpentine heat exchange tube inside the upper furnace body is responsible for absorbing the high-temperature heat generated by combustion. One end of the flue connects to the waste heat steam boiler and air preheater to form a tiered heat energy utilization system of "main heat exchange + waste heat recovery". The other end of the feed hopper enables convenient straw transportation and ensures a continuous fuel supply.

[0007] Preferably, a platform is installed on the top of the upper furnace body, and ladders are installed on the sides of the upper and lower furnace bodies, with the top of the ladders connected to the platform.

[0008] This feature provides workers with a maintenance work space on the top of the furnace body via a platform. Side ladders connect the upper and lower furnace bodies to the platform, forming a continuous operating passage of "ground - lower furnace body - upper furnace body - platform", eliminating the need for additional temporary scaffolding or climbing facilities.

[0009] Preferably, the interior of the upper furnace body is provided with a smoke deflector wall, which forms a serpentine flue gas passage inside the upper furnace body.

[0010] This feature involves using a specific layout to divide the internal space of the furnace through the internal flue walls, forcing the high-temperature flue gas to flow in a "serpentine path" to prevent the flue gas from rushing directly from the combustion chamber to the flue (i.e., "flue gas short circuit"), thus extending the contact time between the flue gas and the serpentine heat exchange tubes inside the furnace.

[0011] Preferably, the upper furnace body is provided with several ash cleaning doors on its side, a slag cleaning port is provided at one end of the upper furnace body, and several ash collection hoppers are installed at the bottom of the upper furnace body, with ash discharge pipes with valves connected to the bottom of the ash collection hoppers.

[0012] This system features an online cleaning door on the side of the furnace body that can directly clean the ash accumulation in the gaps between the heat exchange tubes, an end slag removal port that facilitates the handling of large slag particles remaining in the furnace, a bottom ash collection hopper that centrally collects falling ash and slag, and a valved ash discharge pipeline that can control the timing and amount of ash and slag discharge, forming a multi-dimensional ash and slag cleaning system of "online cleaning + centralized ash collection + controllable ash discharge".

[0013] Preferably, a slag discharge port is provided at the bottom of the combustion chamber.

[0014] This feature allows the ash discharge port at the bottom of the combustion chamber to work in conjunction with the grate, ensuring timely discharge of ash produced after straw combustion and preventing ash from accumulating on the grate surface. Accumulated ash will block the ventilation gaps of the grate, preventing cold air from entering the combustion chamber evenly and affecting the straw combustion effect.

[0015] Preferably, one end of the heat exchange tube is connected to an inlet header and the other end is connected to an outlet header, and the patient medium is sent into the heat exchange tube for circulating heat exchange by a circulating oil pump.

[0016] This setup features inlet and outlet headers at both ends of the heat exchange tubes to achieve "uniform distribution" and "centralized collection" of the organic heat transfer fluid, respectively. The circulating oil pump provides power for the flow of the medium, enabling the medium to form a closed loop circulation within the heat exchange tubes. This ensures that the medium flows through each heat exchange tube, avoiding localized overheating caused by "empty tubes".

[0017] Preferably, the heat exchange tubes include convection serpentine coils, square coils, and roof tubes. The high-temperature flue gas flow is as follows: rising from the combustion chamber → upward along the inside of the square coil → flipping to the outside and downward through the roof tube → entering the heating surface of the front serpentine convection tube → downward along the gaps between the serpentine tubes → reaching the bottom of the serpentine tube and turning 180° upward → entering the heating surface of the rear serpentine convection tube → upward along the gaps between the serpentine tubes → and being discharged through the upper flue.

[0018] This heat exchanger uses a combination design of "convection serpentine coil + square coil + roof tube", which, in conjunction with a specific high-temperature flue gas flow (combustion chamber rises → inside the square coil → roof tube flips → front serpentine tube downwards → bottom bend → rear serpentine tube upwards → flue gas discharge), allows the flue gas to come into contact with the square coil (absorbing high temperature from the top), the roof tube (absorbing heat from the top), and the front / rear serpentine convection tubes (absorbing medium and low temperature heat) in sequence, achieving heat coverage and absorption across the entire temperature range of "high temperature section - medium temperature section - low temperature section".

[0019] Preferably, the furnace walls and insulation layers of the upper and lower furnace bodies are made of double-layer insulation material with a thickness of 100mm.

[0020] This design incorporates double-layer insulation materials for the upper and lower furnace walls and insulation layer, with a thickness of 100mm, which is significantly greater than the traditional single-layer (less than 80mm) structure. The double-layer material forms a "double heat insulation barrier," which can greatly reduce the heat loss of high-temperature flue gas from the furnace through the furnace walls and lower the surface temperature of the furnace body.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0022] This utility model, through structural innovation of the organic heat carrier boiler that burns crop straw, effectively improves various technical limitations of existing straw-burning boilers in practical applications. It achieves significant optimization in terms of thermal energy utilization efficiency, environmental emission performance, equipment operation stability, and ease of operation and maintenance, providing a better solution for heat energy supply in industrial production and agricultural drying scenarios.

[0023] In terms of thermal energy utilization, the serpentine heat exchange tubes and the flue gas deflector inside the boiler's upper furnace body work synergistically. By constructing a reasonable flue gas flow path, the residence time of high-temperature flue gas in the furnace is extended, while the contact range between the flue gas and the heat exchange tubes is expanded, avoiding the problem of insufficient heat exchange that easily occurs in traditional heat exchange structures. Combined with the waste heat steam boiler and air preheater at the end of the flue, the discharged medium- and low-temperature flue gas can be recovered in stages. This generates auxiliary steam and raises the combustion chamber temperature by preheating the air, forming a virtuous cycle of energy utilization. Ultimately, this meets the organic heat carrier's requirement for a stable high-temperature heat source, further improving the overall thermal energy utilization level. Furthermore, the closed-loop system composed of the heat exchange tubes, inlet header, outlet header, and circulating oil pump can precisely control the circulation state of the organic heat carrier, ensuring stable medium temperature and providing continuous and reliable thermal energy support for downstream heat-using equipment.

[0024] Regarding equipment operational stability, the boiler's ash and slag removal structure has been optimized to address the characteristic of straw combustion easily producing ash and slag. The ash removal door on the side of the upper furnace body allows for online maintenance of the heat exchange tube gaps. The bottom ash collection hopper, combined with a valved ash discharge pipeline, enables the orderly collection and discharge of ash and slag. The end slag removal port facilitates the handling of residual slag, effectively reducing downtime caused by ash and slag accumulation and extending the equipment's continuous operating cycle. Simultaneously, the slag discharge port at the bottom of the combustion chamber, in conjunction with the grate, allows for timely removal of ash and slag generated after combustion, preventing it from affecting grate ventilation, ensuring the uniformity of straw combustion, and reducing interference from localized anomalies.

[0025] The boiler also boasts significant advantages in environmental performance and safety. The air inlet duct design at the top of the combustion chamber ensures sufficient air supply to the combustion process, promoting more complete straw combustion, reducing the generation of unburned gases, and, combined with waste heat recovery for flue gas temperature control, helps reduce pollutant emissions, meeting relevant environmental standards and low-carbon development requirements. Furthermore, the double-layer insulation material design of the boiler body effectively reduces heat loss from high-temperature flue gas through the furnace walls, while also lowering the boiler surface temperature. This further improves thermal efficiency and avoids potential safety hazards caused by high surface temperatures.

[0026] In terms of operation, maintenance, and cost control, the platform on top of the furnace body and the side ladders provide convenience for staff to inspect internal components without the need for additional auxiliary facilities. The feed hopper, directly connected to the furnace body, simplifies the straw addition process and reduces manual labor intensity. In addition, the compact layout of each structural component and clear functional zoning reduce the complexity of equipment installation and subsequent maintenance. Combined with the cost advantages of straw fuel itself, this significantly reduces the boiler's total life-cycle operating cost. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0028] Figure 2 This is a side view of the structure of this utility model;

[0029] Figure 3 This is a top view of the structure of this utility model;

[0030] The meanings of the labels in the diagram are as follows:

[0031] 1. Upper furnace body; 11. Heat exchange tubes; 12. Flute wall; 13. Ash removal door; 14. Ash collection hopper; 15. Slag removal port; 2. Lower furnace body; 21. Combustion chamber; 22. Air inlet pipe; 221. Air inlet; 23. Slag discharge port; 3. Foundation; 4. Platform; 41. Ladder; 5. Flue; 6. Waste heat steam boiler; 7. Air preheater; 8. Feed hopper. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] This utility model provides a boiler that uses crop straw as an organic heat carrier, such as... Figures 1-3As shown, the furnace includes an upper furnace body 1, a lower furnace body 2 installed at the bottom of the upper furnace body 1, a foundation 3 installed at the bottom of the lower furnace body 2, heat exchange tubes 11 arranged in a serpentine pattern inside the upper furnace body 1, a combustion chamber 21 inside the lower furnace body 2, a grate installed at the bottom of the combustion chamber 21, an air inlet pipe 22 installed on the upper inner wall of the combustion chamber 21, an air inlet 221 at one end of the air inlet pipe 22, a flue 5 connected to one end of the upper furnace body 1, a waste heat steam boiler 6 and an air preheater 7 connected sequentially to the outer end of the flue 5, and a feed hopper 8 connected to the other end of the upper furnace body 1.

[0034] The system adopts a split structure of "upper furnace body 1 + lower furnace body 2" to achieve functional zoning. The foundation 3 at the bottom of the lower furnace body 2 ensures the stability of the overall equipment. The combustion chamber 21 inside the lower furnace body 2 and the grate constitute the core area for straw combustion. The air inlet pipe 22 (with air inlet 221) on the upper inner wall of the combustion chamber 21 can supplement secondary air and promote more complete straw combustion. The serpentine heat exchange tubes 11 inside the upper furnace body 1 are responsible for absorbing the high-temperature heat generated by combustion. The flue 5 connected to one end of the upper furnace body 1 is connected to the waste heat steam boiler 6 and the air preheater 7 in sequence, forming a cascade heat energy utilization system of "main heat exchange + waste heat recovery". The feed hopper 8 connected to the other end of the upper furnace body 1 realizes convenient straw transportation and ensures continuous fuel supply. The functional zoning design of "Upper Furnace Body 1 - Lower Furnace Body 2" avoids interference between combustion and heat exchange. The serpentine heat exchange tube 11 initially improves heat exchange efficiency, and the secondary air from the air inlet pipe 22 reduces incomplete combustion of straw. The waste heat steam boiler 6 can generate additional auxiliary steam (for heating or auxiliary production), and the air preheater 7 preheats cold air to aid combustion. Dual waste heat recovery reduces the exhaust gas temperature, and the overall thermal energy utilization rate is significantly improved compared to the traditional single furnace body structure. The feed hopper 8 ensures continuous fuel supply and avoids frequent shutdowns for refueling, while the foundation 3 improves the stability of equipment operation and adapts to long-term operation requirements.

[0035] In this embodiment, a platform 4 is installed on the top of the upper furnace body 1, and ladders 41 are installed on the sides of the upper furnace body 1 and the lower furnace body 2, with the top of the ladders 41 connected to the platform 4.

[0036] Platform 4, installed on top of the upper furnace body 1, provides workers with a space for maintenance work on the top of the furnace body. Ladders 41, installed on the sides of the upper furnace body 1 and lower furnace body 2, connect to platform 4 at their tops, forming a continuous operating passage from the ground to the lower furnace body 2, then to the upper furnace body 1, and finally to platform 4, eliminating the need for additional temporary scaffolding or climbing structures. Workers can safely reach platform 4 via ladder 41 to conveniently inspect the top components of the upper furnace body 1 (such as the heat exchanger tube 11 interface and the flue 5 connection) and the side structures of the upper and lower furnace bodies 1 and 2, significantly improving operational safety; avoiding the time and cost of setting up temporary facilities, significantly improving maintenance efficiency, and reducing the difficulty of equipment maintenance.

[0037] Specifically, the interior of the upper furnace body 1 is provided with a smoke deflector wall 12, which forms a serpentine flue gas passage inside the upper furnace body 1.

[0038] The flue gas deflector 12 inside the upper furnace body 1 divides the furnace space through a specific layout, forcing the high-temperature flue gas to flow in a "serpentine path," preventing the flue gas from directly rushing from the combustion chamber 21 to the flue 5 (i.e., "flue gas short-circuiting"), and extending the contact time between the flue gas and the serpentine heat exchange tubes 11 inside the furnace. The serpentine flue gas channel formed by the flue gas deflector 12 significantly extends the residence time of the flue gas inside the furnace and increases the frequency of contact with the heat exchange tubes 11, completely solving the problem of "insufficient heat exchange" in traditional structures without flue gas deflectors. This structural optimization alone can significantly improve the heat exchange efficiency, laying a high-efficiency foundation for the subsequent waste heat recovery (waste heat steam boiler 6, air preheater 7) in the flue 5.

[0039] Furthermore, the upper furnace body 1 is provided with several ash cleaning doors 13 on its side, and a slag cleaning port 15 is provided at one end of the upper furnace body 1. Several ash collection hoppers 14 are installed at the bottom of the upper furnace body 1, and the bottom of the ash collection hoppers 14 is connected to an ash discharge pipe with a valve.

[0040] Several ash-cleaning doors 13 on the side of the upper furnace body 1 can directly clean the ash accumulation in the gaps between the heat exchange tubes 11 online. The slag-cleaning port 15 at one end of the upper furnace body 1 facilitates the handling of large slag particles remaining in the furnace. Several ash-collecting hoppers 14 at the bottom of the upper furnace body 1 collect falling ash and slag. The ash discharge pipeline with valves connected to the bottom of the ash-collecting hoppers 14 can control the timing and amount of ash and slag discharge, forming a multi-dimensional ash and slag cleaning system of "online ash cleaning + centralized ash collection + controllable ash discharge". Ash accumulation in the gaps between the heat exchange tubes 11 can be cleaned through the ash-cleaning doors 13 without the need for a complete shutdown, reducing the decrease in thermal efficiency caused by ash and slag blockage. The ash-collecting hoppers 14 and the ash discharge pipeline prevent ash and slag from scattering and polluting the environment. The slag-cleaning port 15 quickly handles large slag particles. The combination of these three features significantly extends the continuous operation cycle of the equipment compared to traditional structures and significantly reduces the number of shutdowns for ash cleaning.

[0041] Furthermore, a slag discharge port 23 is provided at the bottom of the combustion chamber 21.

[0042] The ash discharge port 23 at the bottom of the combustion chamber 21 works in conjunction with the grate to promptly discharge ash produced after straw combustion, preventing ash accumulation on the grate surface. Accumulated ash can clog the grate's ventilation gaps, preventing cold air from entering the combustion chamber 21 evenly and affecting straw combustion efficiency. Ensuring smooth grate ventilation allows cold air (or air preheated by the air preheater 7) to be evenly distributed in the combustion area of ​​the combustion chamber 21, significantly improving the uniformity of straw combustion and reducing localized flameout due to oxygen deficiency. Timely ash discharge also prevents ash from coking and adhering to the grate at high temperatures, extending the grate's service life and reducing maintenance costs.

[0043] Furthermore, one end of the heat exchange tube 11 is connected to an inlet header, and the other end is connected to an outlet header. The patient medium is sent into the heat exchange tube 11 for circulating heat exchange via a circulating oil pump.

[0044] One end of the heat exchange tube 11 is connected to the inlet header, and the other end is connected to the outlet header. An organic heat transfer fluid is pumped into the heat exchange tube 11 via a circulating oil pump for closed-loop heat exchange. The inlet header ensures uniform distribution of the medium within the multiple heat exchange tubes 11, while the outlet header collects the high-temperature medium after heat exchange, preventing localized overheating caused by a single heat exchange tube 11 operating "empty." The inlet header ensures uniform distribution of the medium within the heat exchange tubes 11, and the circulating oil pump precisely controls the medium flow rate (avoiding insufficient heat exchange due to excessively slow flow and energy waste due to excessively fast flow). Ultimately, this effectively controls the temperature fluctuation range of the organic heat transfer fluid, meeting the demand for a stable high-temperature heat source from downstream heating equipment. Simultaneously, it prevents damage to the heat exchange tubes 11 due to localized overheating, significantly reducing the equipment failure rate.

[0045] Furthermore, the heat exchange tube 11 includes a convection serpentine coil, a square coil, and a roof tube. The high-temperature flue gas flow is as follows: rising from the combustion chamber 21 → upward along the inside of the square coil → flipping to the outside and downward through the roof tube → entering the heating surface of the front serpentine convection tube → downward along the gaps between the serpentine tubes → reaching the bottom of the serpentine tube and turning 180° upward → entering the heating surface of the rear serpentine convection tube → upward along the gaps between the serpentine tubes → and being discharged through the upper flue 5.

[0046] The heat exchange tube 11 includes a convection serpentine coil, a square coil, and a roof tube. It works in conjunction with a specific high-temperature flue gas flow (rising from inside the combustion chamber 21 → upward along the inside of the square coil (belonging to the heat exchange tube 11) → turning downward to the outside of the roof tube (belonging to the heat exchange tube 11) → entering the heating surface of the front serpentine convection tube (belonging to the heat exchange tube 11) → downward along the gaps between the serpentine tubes (belonging to the heat exchange tube 11) → reaching the bottom of the serpentine tube (belonging to the heat exchange tube 11) and turning upward 180° → entering the heating surface of the rear serpentine convection tube (belonging to the heat exchange tube 11) → upward along the gaps between the serpentine tubes (belonging to the heat exchange tube 11) → being discharged to the upper flue duct 5). This allows the flue gas to come into contact with different components of the heat exchange tube 11 in sequence, achieving heat coverage and absorption across the entire temperature range of "high temperature section - medium temperature section - low temperature section". The combined design of heat exchange tube 11 and the specific flue gas path significantly increase the heat exchange area compared to a single serpentine tube structure, changing the flue gas heat absorption from "partial absorption" to "full path absorption," resulting in a significant improvement in boiler thermal efficiency compared to traditional structures. This completely solves the problem of "flue gas heat being discharged through flue 5 before being fully absorbed" in existing technologies, providing core support for organic heat carriers to meet stable high-temperature requirements.

[0047] Furthermore, the furnace walls and insulation layers of the upper furnace body 1 and the lower furnace body 2 are made of double-layer insulation material with a thickness of 100mm.

[0048] The furnace walls and insulation layers of the upper furnace body 1 and lower furnace body 2 utilize double-layer insulation material, with a thickness design far superior to traditional single-layer structures. This double-layer material forms a "double thermal barrier," significantly reducing heat loss from the high-temperature flue gas through the furnace walls of the upper and lower furnace bodies, while also lowering the furnace surface temperature. The heat loss rate is significantly reduced compared to traditional single-layer insulation, further improving the overall thermal efficiency of the boiler. The surface temperatures of the upper and lower furnace bodies are effectively controlled, completely eliminating the risk of burns to workers touching the furnace, while also reducing the thermal impact of high temperatures on surrounding equipment, thus improving the overall safety of the working environment.

[0049] When using the organic heat carrier boiler that burns crop straw, first check the status of each component: confirm the sealing of the connection between the upper furnace body 1 and the lower furnace body 2, that the ash removal door 13 and the ash discharge port 23 are closed, and that the valve of the ash discharge pipe at the bottom of the ash collection hopper 14 is closed; check that the operating parameters of the circulating oil pump, the waste heat steam boiler 6, and the air preheater 7 are normal; inject the organic heat carrier into the inlet header of the heat exchange tube 11 to ensure that the medium fills each heat exchange tube 11 (convection serpentine coil, square coil, and roof tube), and adjust the medium circulation path through the circulating oil pump to confirm that the medium flow between the inlet header, the outlet header, and the heat exchange tube 11 is smooth.

[0050] Crop straw is added to the combustion chamber 21 through the feed hopper 8 at the other end of the upper furnace body 1. The straw falls onto the grate at the bottom of the combustion chamber 21. The ignition device is activated to ignite the straw, and at the same time, the air inlet 221 of the air inlet pipe 22 is opened to deliver secondary air to the upper part of the combustion chamber 21. The secondary air mixes fully with the incompletely burned gas produced by the straw combustion, promoting continuous and complete combustion of the straw and avoiding black smoke or flameout caused by local oxygen deficiency. During the combustion process, the foundation 3 at the bottom of the lower furnace body 2 ensures the stability of the furnace body and avoids the impact of combustion vibration on the operation of the equipment.

[0051] The high-temperature flue gas generated by the combustion of straw in the combustion chamber 21 enters the upper furnace body 1 upwards along the combustion chamber 21. The flue gas first flows upwards along the inside of the square coil in the heat exchange tube 11, where the square coil absorbs heat from the high-temperature section. After reaching the top of the upper furnace body 1, it is blocked by the roof tube (which is part of the heat exchange tube 11) and flips to the outside downwards, entering the heating surface of the front serpentine convection tube (which is part of the heat exchange tube 11). It flows downwards along the gaps between the serpentine tubes, where the front serpentine tube absorbs heat from the medium-temperature section. After reaching the bottom of the serpentine tube, it turns 180° upwards and enters the heating surface of the rear serpentine convection tube (which is part of the heat exchange tube 11), flowing upwards along the gaps between the serpentine tubes, where the rear serpentine tube absorbs heat from the low-temperature section. During this process, the flue gas deflector 12 forces the flue gas to flow along the aforementioned serpentine path, preventing the flue gas from directly entering the flue 5 from the combustion chamber 21, ensuring the smooth flow of the flue gas through the heat exchange tube 11. Sufficient contact is achieved to transfer heat to the organic heat carrier inside the tube. Driven by the circulating oil pump, the organic heat carrier is evenly distributed from the inlet header to each heat exchange tube 11. After absorbing heat, it is collected in the outlet header and transported to the downstream heat-using equipment to complete one heat exchange cycle.

[0052] After heat exchange in the upper furnace body 1, the medium- and low-temperature flue gas enters the waste heat steam boiler 6 through the flue 5 at one end of the upper furnace body 1. The waste heat steam boiler 6 absorbs the waste heat of the flue gas and heats the internal water to generate low-pressure steam, which can be used for auxiliary production (such as material drying) or plant heating. The flue gas after passing through the waste heat steam boiler 6 continues to enter the air preheater 7, which heats the cold air to a certain temperature and then sends the preheated air into the combustion chamber 21 (in coordination with the secondary air in the air inlet duct 22), increasing the initial temperature of the combustion chamber 21 and reducing fuel consumption. The low-temperature flue gas that has completed waste heat recovery is discharged from the air preheater 7, greatly reducing the heat loss carried away by the exhaust.

[0053] During equipment operation, regular ash and slag removal is performed to prevent ash and slag accumulation from affecting efficiency: Ash removal: Open the ash removal door 13 on the side of the upper furnace body 1 and use a special tool to clean the ash accumulated in the gaps between the heat exchange tubes 11. The ash removal process does not require stopping the machine and does not affect normal heat exchange. The cleaned ash and slag fall into the ash collection hopper 14 at the bottom of the upper furnace body 1. After the ash collection hopper 14 is full, open the valve of the bottom ash discharge pipeline to discharge the ash and slag to the designated collection device. Slag removal: The combustion residue on the grate at the bottom of the combustion chamber 21 is discharged by the slag discharge device (such as a scraper conveyor) by opening the slag discharge port 23 at the bottom of the combustion chamber 21 to ensure smooth grate ventilation and not affect straw combustion.

[0054] During continuous operation, staff can periodically climb onto platform 4 at the top of upper furnace body 1 and onto the side ladder 41 to check the sealing of the heat exchange tube 11 interface and flue 5 connection at the top of upper furnace body 1 to prevent air and smoke leakage. The double-layer insulation layer (upper furnace body 1 and lower furnace body 2 furnace wall) continuously reduces heat loss from the furnace body and maintains a stable furnace temperature. When shutdown is required, first stop adding straw to the feed hopper 8. After the straw in the combustion chamber 21 has burned out, close the air inlet 221 of the air inlet pipe 22 and stop the circulating oil pump. After the furnace temperature drops to a safe range, thoroughly clean the residual ash and slag from the ash collection hopper 14 and slag discharge port 23, turn off the power to all equipment, and complete the current operating cycle.

[0055] Finally, it should be noted that the electronic components in the waste heat steam boiler 6, air preheater 7, etc. in this embodiment are all general standard parts or parts known to those skilled in the art. Their structure and principle can be learned by those skilled in the art through technical manuals or conventional experimental methods. In the idle part of this device, all the above-mentioned electrical components are connected by wires. The specific connection method should refer to the working order between each electrical component in the above working principle to complete the electrical connection. All of these are technologies known in the art.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A boiler that burns crop straw as an organic heat carrier, comprising an upper furnace body (1), characterized in that: The lower part of the upper furnace body (1) is equipped with a lower furnace body (2), and the bottom of the lower furnace body (2) is equipped with a foundation (3). The interior of the upper furnace body (1) is equipped with heat exchange tubes (11) arranged in a serpentine pattern. The interior of the lower furnace body (2) is equipped with a combustion chamber (21). The bottom of the combustion chamber (21) is equipped with a grate. The upper inner wall of the combustion chamber (21) is equipped with an air inlet pipe (22). One end of the air inlet pipe (22) is equipped with an air inlet (221). One end of the upper furnace body (1) is connected to a flue (5). The outer end of the flue (5) is connected in sequence to a waste heat steam boiler (6) and an air preheater (7). The other end of the upper furnace body (1) is connected to a feed hopper (8).

2. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: A platform (4) is installed on the top of the upper furnace body (1), and ladders (41) are installed on the sides of the upper furnace body (1) and the lower furnace body (2). The top of the ladders (41) is connected to the platform (4).

3. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: The interior of the upper furnace body (1) is provided with a smoke deflector wall (12), which forms a serpentine flue gas passage inside the upper furnace body (1).

4. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: The upper furnace body (1) is provided with several ash cleaning doors (13) on its side, and a slag cleaning port (15) is provided at one end of the upper furnace body (1). Several ash collection hoppers (14) are installed at the bottom of the upper furnace body (1), and the bottom of the ash collection hoppers (14) is connected to an ash discharge pipe with a valve.

5. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: The bottom of the combustion chamber (21) is provided with a slag discharge port (23).

6. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: One end of the heat exchange tube (11) is connected to an inlet header, and the other end is connected to an outlet header. The patient medium is sent into the heat exchange tube (11) for circulating heat exchange by a circulating oil pump.

7. The organic heat carrier boiler burning crop straw according to claim 6, characterized in that: The heat exchange tube (11) includes a convection serpentine coil, a square coil, and a roof tube. The high-temperature flue gas flow is as follows: rising from the combustion chamber (21) → going up along the inside of the square coil → turning to the outside and going down through the roof tube → entering the heating surface of the front serpentine convection tube → going down along the gap between the serpentine tubes → reaching the bottom of the serpentine tube and turning 180° upward → entering the heating surface of the rear serpentine convection tube → going up along the gap between the serpentine tubes → being discharged through the upper flue (5).

8. The organic heat carrier boiler burning crop straw according to claim 1, characterized in that: The furnace walls and insulation layers of the upper furnace body (1) and the lower furnace body (2) are made of double-layer insulation material with a thickness of 100mm.

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