A condensing steam boiler

Abstract

The present invention discloses a condensing steam boiler, comprising a furnace and a plurality of heat exchange tubes disposed therein. The plurality of heat exchange tubes are arranged in a ring to form a heat exchange tube coil. The heat exchange tube coil is characterized in that a heat insulation component is disposed on the inner side of the heat exchange tube coil, the heat insulation component separating the heat exchange tube coil into a main heat exchange zone and a superheat zone. One end of the heat exchange tube is a water inlet, and the other end is a steam outlet. The water inlet is disposed on one side of the main heat exchange zone, and the steam outlet is disposed on one side of the superheat zone. The medium within the heat exchange tube is divided into a liquid phase zone, a vapor-liquid two-phase mixed zone, and a vapor phase zone from the water inlet to the steam outlet. The liquid phase zone is disposed in the main heat exchange zone, the vapor phase zone is disposed in the superheat zone, and the vapor-liquid two-phase mixed zone is disposed at the junction of the main heat exchange zone and the superheat zone. The present invention improves heat exchange efficiency, extends service life, and reduces maintenance requirements.

Description

Technical Field

[0001] The present invention relates to a boiler, in particular to a condensing steam boiler. Background Art

[0002] A steam generator, also known as a steam heat source machine (commonly known as a boiler), is a mechanical device that uses the thermal energy of fuel or other energy sources to heat water into hot water or steam. Traditional steam generators are generally horizontal or vertical. The general operating principle (using water flowing upward through heat exchange tubes as an example) is as follows: the heat exchange tubes are heated, converting the liquid in the tubes into a vapor state. A steam drum is positioned above the tubes to allow the vapor to escape through the drum. Steam generators with a water volume greater than or equal to 30L are considered special equipment and require supervisory inspection and registration. Steam generators with a water volume less than 30L do not fall under the category of special equipment and do not require supervisory inspection, registration, or annual inspection.

[0003] For gas-fired steam generators exempt from inspection or reporting, or for conventional steam generators, in order to minimize their size, existing structures, such as vertical equipment, generally use a circle of heat exchange tubes. The interior of this circle of heat exchange tubes serves as the combustion zone, and high-temperature flue gas and heat radiation are used to heat this circle of heat exchange tubes, heating the liquid in the heat exchange tubes into vapor (liquid medium is fed into the heat exchange tubes from the bottom, and vapor medium is discharged from the top). This structure has the following problems:

[0004] Since the water in the heat exchange tube is gradually heated from liquid to vapor from bottom to top, that is, the heat exchange tube is liquid, vapor-liquid mixed state, and vapor from bottom to top, and the vapor state has poor heat transfer performance, but the temperature at each location in the combustion area is basically the same. The high temperature experienced by the heat exchange tube in the liquid area and vapor-liquid mixed state area can be directly transferred to the liquid water, heating it. For example, the heat exchange tube in the lower liquid and vapor-liquid mixed state is exposed to a temperature of 800℃-1000℃, which can transfer heat to the liquid water, heating it to vapor. Dry burning of the heat exchange tube will not occur, thus preventing the heat exchange tube from being burned. However, due to the poor heat transfer performance of the vapor state, the heat exchange tube in the vapor area is basically dry burning, and the temperature may be close to 500℃ or even exceed 500℃. To address this issue, conventional steam generators use heat-resistant alloy steel in the upper heat exchange tubes (in the vapor phase area). This special alloy can withstand temperatures exceeding 500 degrees Celsius. However, due to the frequent dry-burning in this area, even the heat-resistant alloy steel is easily damaged, resulting in a relatively short service life and a high maintenance rate. Furthermore, the heat-resistant alloy steel is relatively expensive.

[0005] While lowering the temperature can extend service life and reduce maintenance, it also poses the problem of insufficient steam dryness. If the steam contains no liquid water, the steam dryness is 100%. Standard boilers should have a steam dryness of at least 97%, and high-quality boilers should have a steam dryness of at least 99%. Insufficient steam dryness results in significant heat loss and increased energy consumption (for example, in a gas-fired steam generator, this increases gas consumption). Furthermore, if the steam contains a high amount of water, it may not meet the production process requirements of some end users. Summary of the Invention

[0006] The purpose of the present invention is to provide a condensing steam boiler. By using this structure, the service life of the equipment can be effectively extended, the maintenance rate and cost can be reduced, and the use effect of the equipment can be effectively guaranteed.

[0007] To achieve the above-mentioned object, the present invention adopts the following technical solution: a condensing steam boiler, comprising a furnace and a plurality of heat exchange tubes arranged in the furnace, wherein the plurality of heat exchange tubes are arranged in a ring to form a heat exchange tube coil, wherein a heat insulation component is provided on the inner side of the heat exchange tube coil, and the heat insulation component separates the heat exchange tube coil into a main heat exchange zone and a superheating zone, wherein the main heat exchange zone is a combustion zone, and the superheating zone is a secondary heat exchange zone for high-temperature flue gas;

[0008] One end of the heat exchange tube is a water inlet, and the other end is a steam outlet. The water inlet is arranged on one side of the main heat exchange zone, and the steam outlet is arranged on one side of the superheat zone. The liquid medium enters the heat exchange tube through the water inlet, is heated into a vapor state in the main heat exchange zone and the superheat zone, and then is discharged from the steam outlet.

[0009] The medium in the heat exchange tube is divided into a liquid phase zone, a vapor-liquid two-phase mixing zone and a vapor state zone from the water inlet to the steam outlet. The liquid phase zone is arranged at the main heat exchange zone, the vapor state zone is arranged at the superheat zone, and the vapor-liquid two-phase mixing zone is arranged at the connection between the main heat exchange zone and the superheat zone.

[0010] In the above technical solution, the outer surface of the heat insulation component is against the inner surface of the heat exchange tube ring.

[0011] In the above technical solution, a plurality of fins are provided at intervals on the outer surface of each heat exchange tube, and the plurality of fins are arranged along the extension direction of the heat exchange tube.

[0012] In the above technical solution, the two opposite sides of the fin are respectively provided with bends, the bends abut against the bends of the adjacent upper or lower fins, and the outside of the heat exchange tube between the two adjacent fins forms a flue gas channel;

[0013] And / or, the side of the fin on each heat exchange tube contacts the side of the fin on the adjacent heat exchange tube, or the side of the fin on each heat exchange tube is arranged close to the side of the fin on the adjacent heat exchange tube.

[0014] In the above technical solution, the bent end of the fin at the main heat exchange area is arranged on the outside of the heat exchange tube coil.

[0015] In the above technical solution, the bent end of the fin at the superheating zone is arranged on the outside of the heat exchange tube ring;

[0016] And / or, the other bent end of the fin at the superheating zone is arranged on the inner side of the heat exchange tube coil.

[0017] In the above technical solution, a plurality of outer guide plates are further provided on the outside of the heat exchange tube ring, the side of each outer guide plate is connected to or contacts the side of the adjacent outer guide plate, each outer guide plate is arranged opposite a heat exchange tube, and the outer guide plates are connected to the fins or heat exchange tubes;

[0018] And / or, a plurality of inner guide plates are provided in the superheating zone, the side of each inner guide plate is connected to or contacts the side of the adjacent inner guide plate, each inner guide plate is arranged opposite a heat exchange tube, and the inner guide plate is connected to the fin or heat exchange tube.

[0019] In the above technical solution, a plurality of outer guide plates are further provided on the outer side of the heat exchange tube ring, the side of each outer guide plate is connected to or in contact with the side of the adjacent outer guide plate, each outer guide plate is arranged opposite a heat exchange tube, and the outer guide plate is connected to the heat exchange tube;

[0020] And / or, a plurality of inner guide plates are provided in the superheating zone, the side of each inner guide plate is connected to or contacts the side of the adjacent inner guide plate, each inner guide plate is arranged opposite a heat exchange tube, and the inner guide plate is connected to the heat exchange tube.

[0021] In the above technical solution, the outer guide plate and the inner guide plate are respectively provided with through holes.

[0022] In the above technical solution, the through-hole size in the vapor region is larger than that in the liquid region, and the through-hole size in the liquid region is larger than that in the vapor-liquid two-phase mixing region.

[0023] In the above technical solution, a disturbance embedded tube is further provided in each heat exchange tube, the disturbance embedded tube is arranged in the vapor zone, and there is a distance between the disturbance embedded tube and the inner wall of the heat exchange tube;

[0024] And / or, the disturbance embedded tube is coaxially arranged with the heat exchange tube.

[0025] In the above technical solution, the heat exchange tube is arranged vertically, the bottom of the heat exchange tube is the water inlet, and the top of the heat exchange tube is the steam outlet;

[0026] And / or, a water inlet header and a steam header are respectively provided at the bottom and top of the furnace, the water inlet at the bottom of the heat exchange tube is connected to the water inlet header, and the steam outlet at the top of the heat exchange tube is connected to the steam header.

[0027] In the above technical solution, a steam exhaust port is provided on the top of the steam header, a steam-water separation plate is provided inside the steam header, and the steam-water separation plate is arranged between the steam exhaust port and the steam outlet;

[0028] And / or, the steam-water separation plate is a multi-stage steam-water separation plate.

[0029] In the above technical solution, a condensing heat exchanger is further provided beside the furnace, and a plurality of rows of condensing side heat exchange tubes arranged at intervals are provided in the condensing heat exchanger;

[0030] A first smoke exhaust port is provided on the superheating zone, and the first smoke exhaust port is connected to the smoke inlet of the condensing heat exchanger;

[0031] The condensing heat exchanger is provided with a smoke exhaust pipe, and the smoke inlet and the smoke exhaust pipe are respectively arranged on both sides of the condensing side heat exchange pipe.

[0032] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0033] 1. In the present invention, a heat insulation component is directly set inside the heat exchange tube ring, which divides the heat exchange tube ring into a combustion area and a high-temperature flue gas secondary heat exchange area. The liquid medium in the heat exchange tube is in the combustion area, and the vapor medium in the heat exchange tube is in the high-temperature flue gas secondary heat exchange area. In this way, the combustion area exchanges heat with the liquid medium with strong heat transfer performance, and the high-temperature flue gas with higher temperature can be concentrated in the combustion area to exchange heat with the liquid medium, while the high-temperature flue gas with lower temperature performs secondary heating on the vapor medium, effectively improving the steam dryness. At the same time, it can also prevent the heat exchange tubes in the vapor area from being damaged by high temperature for a long time. In addition, the vapor-liquid two-phase mixing area is located in the heat insulation component, which can prevent dry burning in the vapor-liquid two-phase mixing area, effectively reducing the maintenance rate and extending the service life. It does not need to use high-temperature resistant steel, which can reduce costs.

[0034] 2. The present invention can improve the utilization rate of thermal energy, reduce energy consumption and use costs;

[0035] 3. The present invention also provides fins to improve the heat exchange effect. At the same time, the fins are also bent to form a flue gas channel, allowing the high-temperature flue gas to contact the back of the combustion area as much as possible, ensuring uniform heat exchange at all locations of the heat exchange tube, reducing the heat exchange intensity difference, reducing the temperature difference of the heat exchange tube wall, and ensuring uniform heat exchange in the circumferential direction of the heat exchange tube, thereby extending the service life of the heat exchange tube;

[0036] 4. The present invention also provides inner and outer guide plates to control the flow path of high-temperature flue gas, thereby ensuring and controlling the heat exchange effect;

[0037] 5. In the present invention, a disturbance embedded tube is also provided in the heat exchange tube, which can improve the steam dryness and slightly superheated state. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural diagram of the first embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the three-dimensional structure of the first embodiment of the present invention (arrows indicate the flow path and direction of the flue gas from the superheating zone toward the condensing heat exchanger);

[0040] Figure 3 yes Figure 1 Schematic diagram of the cross-sectional structure of AA (arrows indicate the flow path and direction of the flue gas);

[0041] Figure 4 yes Figure 1 Schematic diagram of the cross-sectional structure of the middle BB;

[0042] Figure 5 This is a partial enlarged view of the flow path of flue gas surrounding the heat exchange tubes in the main heat exchange zone in Example 1 of the present invention (the arrows indicate the flow path and direction of the flue gas);

[0043] Figure 6 1 is a schematic diagram of the cross-sectional structure of the heat insulation component and a single heat exchange tube in Example 1 of the present invention (with medium inside the heat exchange tube);

[0044] Figure 7 It is a partial enlarged view of the connection between the heat exchange tube and the steam header in the first embodiment of the present invention.

[0045] Among them: 1. Furnace; 2. Heat exchange tube; 3. Heat exchange tube ring; 4. Insulation component; 5. Main heat exchange area; 6. Superheating area; 7. First smoke exhaust port; 8. Water inlet; 9. Steam outlet; 10. Liquid phase area; 11. Gas-liquid two-phase mixing area; 12. Gas phase area; 13. Fin; 14. Bend; 15. Flue gas channel; 16. Outer guide plate; 17. Through hole; 18. Inner guide plate; 19. Disturbance embedded tube; 20. Water inlet header; 21. Steam header; 22. Steam outlet; 23. Steam-water separator; 24. First-stage steam-water separator; 25. Second-stage steam-water separator; 26. Condensing heat exchanger; 27. Smoke exhaust pipe; 28. Back-fire area of main heat exchange area; 29. Burner. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0047] Example 1: See Figure 1-7 As shown, a condensing steam boiler includes a furnace 1 and a plurality of heat exchange tubes 2 arranged in the furnace 1. The plurality of heat exchange tubes 2 are arranged in a ring to form a heat exchange tube ring 3, and there is a distance between adjacent heat exchange tubes 2. A heat insulation component 4 is provided on the inner side of the heat exchange tube ring 3. The heat insulation component 4 separates the heat exchange tube ring 3 into a main heat exchange zone 5 and an overheating zone 6. The main heat exchange zone 5 is a combustion zone, and the overheating zone 6 is a secondary heat exchange zone for high-temperature flue gas; the overheating zone 6 away from the heat insulation component 4 is a first smoke exhaust port 7.

[0048] One end of the heat exchange tube 2 is a water inlet 8, and the other end is a steam outlet 9. The water inlet 8 is arranged on one side of the main heat exchange zone 5, and the steam outlet 9 is arranged on one side of the superheat zone 6. The liquid medium enters the heat exchange tube 2 through the water inlet 8, is heated into a vapor state in the main heat exchange zone 5 and the superheat zone 6, and then is discharged from the steam outlet 9.

[0049] The medium in the heat exchange tube 2 is respectively a liquid phase zone 10, a vapor-liquid two-phase mixing zone 11 and a vapor zone 12 from the water inlet 8 to the steam outlet 9. The liquid phase zone 10 is arranged on the side of the main heat exchange zone 5, the vapor zone 12 is arranged on the side of the superheat zone 6, the vapor-liquid two-phase mixing zone 11 is arranged at the connection between the main heat exchange zone 5 and the superheat zone 6, and the two ends of the vapor-liquid two-phase mixing zone 11 are respectively arranged on the side of the main heat exchange zone 5 and the side of the superheat zone 6.

[0050] In this embodiment, the heat exchange tube ring forms an annular structure, and the heat insulation component is arranged inside the annular structure. The outer surface of the heat insulation component is against the inner surface of the heat exchange tube ring, thereby dividing the annular structure into two chambers: a main heat exchange zone and a superheat zone, wherein the main heat exchange zone is a combustion zone, in which a burner 29 can be arranged, while no burner is arranged in the superheat zone. The high-temperature flue gas and heat radiation generated by the burner will be directly transmitted to the heat exchange tube ring outside it, that is, to the heat exchange tube on the side of the main heat exchange zone. Since the heat exchange tube in the main heat exchange zone is mainly a liquid phase zone, that is, the heat exchange tube in the main heat exchange zone is mainly liquid water, taking the direction shown in the figure as an example, the bottom of the heat exchange tube is the water inlet, and liquid water enters the heat exchange tube from the water inlet, and is heat-exchanged with the heat exchange tube through the heat radiation of the combustion zone and the high-temperature flue gas, so that the liquid water gradually vaporizes. The liquid surface of the liquid phase zone is arranged close to the bottom surface of the heat-insulating component. In this embodiment, the heat-insulating component is made of refractory bricks or other heat-insulating materials or heat-insulating materials. When water boils and vaporizes, it will produce more bubbles, and the bubbles rise through the liquid surface, that is, the heat-insulating component (the connection between the main heat exchange zone and the superheated zone) forms a gas-liquid two-phase mixing zone. The heat exchange tubes in this area contain part liquid water and part water vapor. Taking the high-temperature flue gas temperature in the combustion zone as 800℃-1000℃ as an example, after the high-temperature flue gas exchanges heat with the heat exchange tubes in the main heat exchange zone, the high-temperature flue gas in the main heat exchange zone will be sent out from the gap between adjacent heat exchange tubes to the outside of the heat exchange tube ring (the back-fire area 28 of the main heat exchange zone). The temperature of the high-temperature flue gas sent out to the outside of the heat exchange tube ring is about 300℃-350℃, and then it will be mixed with the superheated zone. The outer surface of the heat exchange tube on the outside of the heat exchange tube coil in the zone contacts the heat exchange, and then enters the superheat zone through the gap between the adjacent heat exchange tubes in the superheat zone, and contacts the outer surface of the heat exchange tube on the inside of the heat exchange tube coil in the superheat zone for heat exchange. At this time, the high-temperature flue gas inside the superheat zone is about 180-200°C, while the steam temperature in the vapor-liquid two-phase mixing zone and the vapor zone is about 160-180°C. In this way, the high-temperature flue gas in the superheat zone and outside the superheat zone can be used to exchange heat with the steam and water mist in the heat exchange tube again, thereby improving the steam dryness. At the same time, the contact temperature of the high-temperature flue gas and the heat exchange tube in the vapor zone will not exceed 400°C, so there will be no overheating problem of the heat exchange tube, effectively preventing damage to the heat exchange tube, effectively reducing the maintenance rate, and extending the service life. At the same time, the heat exchange tube is made of ordinary boiler steel, without the need to use higher-cost high-temperature resistant materials, which can effectively reduce costs.

[0051] Moreover, in this embodiment, by setting up the heat-insulating components, the high-temperature zone can be basically controlled in the liquid phase zone, and heat exchange can be carried out with liquid water as much as possible. Since liquid water has good heat transfer performance, its heat exchange effect is good, which effectively improves the heat exchange effect, saves energy consumption, and can also reduce the cost of use.

[0052] Moreover, when the heat exchange tube is subjected to high temperature, liquid water will hang on the tube wall of the heat exchange tube in the gas-liquid two-phase mixing area (liquid water will exist within a certain distance on the tube wall above the liquid surface and will be in contact with the tube wall of the heat exchange tube. There is no liquid water near the axis of the heat exchange tube, or only a part of the liquid water is brought out by the bubbles, and the middle part is mainly water vapor with not particularly high dryness). The liquid water has stronger heat transfer performance and better heat exchange effect, which can effectively prevent the dry burning problem of the heat exchange tube on the main heat exchange area side of the insulation component, prevent damage to the heat exchange tube at the insulation component, and effectively ensure the service life.

[0053] Furthermore, in order to improve the heat transfer effect, see Figure 5 As shown, each heat exchange tube 2 is provided with multiple fins 13 at intervals on its outer surface, arranged along the extension direction of the heat exchange tube 2. In this configuration, the heat exchange tubes are finned, which increases the contact area between the heat exchange tubes and the high-temperature flue gas, thereby improving the heat exchange effect. Of course, due to the higher temperatures in the main heat exchange zone, finned tubes can also be omitted, and bare tubes (without fins and a smooth surface) can be used.

[0054] See also Figure 5 As shown, the fins 13 are provided with bends 14 on opposite sides, respectively. The bends 14 abut against the bends 14 of the adjacent upper or lower fins 13 , and the outside of the heat exchange tube 2 between the two adjacent fins 13 forms a flue gas channel 15 .

[0055] In this embodiment, all the fins are bent downward on both sides (of course, they can also be bent upward). If no bending is set, the fins will increase the contact area with the flue gas, thereby improving the heat exchange effect. At the same time, when the high-temperature flue gas in the main heat exchange zone passes through the heat exchange tube and is sent out of the heat exchange tube ring, the flue gas will contact the outer surface of the inner end of the heat exchange tube (the inner side of the heat exchange tube ring, that is, the combustion area side), and its contact area with the outer end of the heat exchange tube (the outer side of the heat exchange tube ring, that is, the back-fire area side of the main heat exchange zone) will be smaller. Since the heat exchange tube on the combustion area side is subjected to better thermal radiation heat exchange and thermal convection heat exchange effects and high heat exchange intensity, the thermal radiation heat exchange and thermal convection heat exchange effects in the back-fire area of the main heat exchange zone will be worse, resulting in a larger temperature difference between the tube wall inner and outer ends of the heat exchange tube, thereby affecting the service life of the heat exchange tube. Therefore, in this embodiment, the bending setting is used to adjust the flow path of the high-temperature flue gas through the heat exchange tube, to increase the contact area and / or time between the high-temperature flue gas and the back-fire area side of the main heat exchange zone of the heat exchange tube, to make the heat exchange of the heat exchange tube more uniform in the circumferential direction as much as possible, to reduce the temperature difference between the tube wall at the inner and outer ends of the heat exchange tube, and to extend the service life of the heat exchange tube.

[0056] Furthermore, to ensure the heat exchange effect and the contact area and heat exchange effect between the high-temperature flue gas and the fins and heat exchange tubes, the side of the fin on each heat exchange tube contacts the side of the fin on the adjacent heat exchange tube, or the side of the fin on each heat exchange tube is arranged close to the side of the fin on the adjacent heat exchange tube. In this way, the high-temperature flue gas is sent from the main heat exchange zone to the outside of the heat exchange tube coil and enters the superheat zone from the outside of the heat exchange tube coil. The high-temperature flue gas can only or mostly pass through the flue gas channel and flows along the path of the flue gas channel, trying not to flow out from the gap between the fins of adjacent heat exchange tubes. This can fully ensure the contact between the high-temperature flue gas and the fins and heat exchange tubes, effectively improve the heat exchange effect, fully utilize thermal energy, save energy consumption, and reduce usage costs.

[0057] See also Figure 5 As shown, in order to accurately control the flow direction of the flue gas, one end of the bend of the fin 13 at the main heat exchange zone 5 is set on the outside of the heat exchange tube ring 3. The two bends are symmetrically arranged on both sides of the fin, one end of the bend is arranged between adjacent heat exchange tubes, and the other end is outside the heat exchange tube ring. In this way, since the main heat exchange zone is the combustion zone, the heat radiation therein is stronger, the temperature of the high-temperature flue gas is higher, and the heat exchange effect is better. Therefore, one end of the fin at the main heat exchange zone is on the outside of the heat exchange tube ring, that is, the bend of the fin of the heat exchange tube at this location is at the outer end of the heat exchange tube, and the other end is not set in the main heat exchange zone, that is, the bend is mainly in the back-fire area of the main heat exchange zone. A flue gas outlet is formed between the two bends. The outlet is preferably smaller than the diameter of the heat exchange tube, or smaller than the radius of the heat exchange tube, and the flue gas outlet is set opposite the axis of the heat exchange tube ring, while the side of the fin in the main heat exchange zone is not set with a bend, which can ensure the main heat exchange zone. The high-temperature flue gas inside fully contacts and exchanges heat with the inner side of the heat exchange tube. The flue gas channel in the main heat exchange area is an arc-shaped channel. The flue gas flows outward from both sides of the heat exchange tube between the upper and lower adjacent fins. Then, due to the existence of the bend, the flow path of the flue gas will be changed. It will flow around the heat exchange tube, flow toward the outer ends of the two bends, and flow out from the flue gas outlet, which can make the flue gas flow around the outer surface of the heat exchange tube and contact the back-fire side of the heat exchange tube, and can enhance the convective heat exchange between the high-temperature flue gas and the heat exchange tube in the back-fire area of the main heat exchange area, thereby reducing the temperature difference of the tube wall of the heat exchange tube, improving the uniformity of heat exchange in the circumferential direction of the heat exchange tube, and extending the service life of the heat exchange tube.

[0058] Similarly, one end of the bend of the fin in the superheat zone is located inside the heat exchange tube coil. Two bends are symmetrically located on either side of the middle of the fin, with one end located between adjacent heat exchange tubes and the other end located inside the heat exchange tube coil. This is within the superheat zone, meaning that most of the bend is located within the superheat zone. Because the temperature of the high-temperature flue gas outside the heat exchange tube coil exceeds that of the high-temperature flue gas within the superheat zone, this can enhance the heat exchange effect of the heat exchange tube in the superheat zone, improve the uniformity of heat exchange in the circumferential direction of the heat exchange tube in the superheat zone, and extend the service life of the heat exchange tube.

[0059] Of course, as another embodiment, all the bends are only arranged on the outside of the heat exchange tube ring (which can reduce the processing difficulty and reduce the production cost), that is, all the bends are in the back-fire area of the main heat exchange zone, because the temperature of the high-temperature flue gas in the superheating zone and the back-fire area of the main heat exchange zone is not very high, and the temperature difference is only more than 100 degrees Celsius (the temperature difference between the main heat exchange zone and the back-fire area of the main heat exchange zone may be close to 500℃~700℃, which is a particularly large temperature difference), and the heat exchange is relatively uniform, which will not affect the service life of the heat exchange tube.

[0060] As another preferred embodiment, one end of the bend of the fin in the overheating zone is disposed on the outside of the heat exchange tube coil; the other end of the bend of the fin in the overheating zone is disposed on the inside of the heat exchange tube coil. That is, the bends in the overheating zone are symmetrically disposed on opposite sides of the heat exchange tube, with one end of the bend on the outside of the heat exchange tube coil and the other end on the inside of the heat exchange tube coil. This ensures that the smoke inlet and smoke outlet of the flue gas channel in the overheating zone are smaller than the diameter or radius of the heat exchange tube. In this way, when the flue gas passes through the flue gas channel, the high-temperature flue gas will first contact the outer end of the heat exchange tube for heat exchange, then contact the inner end of the heat exchange tube, and then be discharged from the inner end of the heat exchange tube, so that the high-temperature flue gas fully contacts the circumferential side of the heat exchange tube, thereby improving the heat exchange effect.

[0061] See also Figure 5 As shown, a plurality of outer guide plates 16 are further provided on the outside of the heat exchange tube coil 3. The sides of each outer guide plate 16 are connected to or in contact with the sides of adjacent outer guide plates 16. Each outer guide plate 16 is provided opposite a heat exchange tube 2 and is connected to the fins 13 or the heat exchange tube 2. Through holes 17 are provided on the outer guide plates 16.

[0062] In the present invention, the outer guide plate has two installation structures: the outer guide plate is connected to the heat exchange tube, or the outer guide plate is connected to the fin. If fins are not provided, the outer guide plates are directly connected to the heat exchange tubes. Since the outer guide plates are connected to each other, they form an annular structure, which is equivalent to providing an annular cover on the outside of the heat exchange tube ring (the outer guide plates can only be in contact with the heat exchange tubes at the edges or part of the edges, or can be in contact with the heat exchange tubes through support rods, so as not to affect the flue gas from being sent out from the main heat exchange zone and then into the superheating zone), and the outer guide plates will be provided close to the heat exchange tube ring, so that the high-temperature flue gas in the main heat exchange zone will be restricted by the annular cover after coming out of the heat exchange tube ring, so that the high-temperature flue gas can contact various positions of the heat exchange tube as much as possible, thereby improving the heat exchange effect. At the same time, in order to enable the heat exchange flue gas to be smoothly sent out of the outer guide plates and then enter the superheating zone, a through hole is also provided, so that the high-temperature flue gas can be sent out of the outer guide plates from the through hole and then sent into the superheating zone from the outer guide plates. More preferably, the through hole is arranged directly opposite the axis of the heat exchange tube ring, and there are multiple through holes, which are spaced apart along the length direction of the outer guide plate. In this way, the high-temperature flue gas sent out from the main heat exchange area will be blocked by the outer guide plate, and will be fully contacted with the back-fire area of the main heat exchange area of the heat exchange tube for heat exchange before being sent out from the through hole. This not only ensures the heat exchange effect, but also makes the temperature difference of the tube wall of the heat exchange tube small and the service life long.

[0063] If fins are provided, it is difficult to ensure that all fins on the heat exchange tubes are in contact with the fins on adjacent heat exchange tubes during assembly of the heat exchange tubes, resulting in spacing between the fins on adjacent heat exchange tubes. Consequently, some high-temperature flue gas will flow between the fins between adjacent heat exchange tubes, which will affect the heat exchange effect. Therefore, an outer guide plate is provided, the inner wall of which is connected to the fins on each heat exchange tube, equivalent to a cylindrical structure composed of multiple fins with an annular outer guide plate wrapped around the outside. Furthermore, adjacent outer guide plates are in contact or connected with each other, preferably by overlapping or snapping, so that the annular structure composed of multiple outer guide plates wraps around the outside of the heat exchange tube ring, and the through-hole on each outer guide plate is directly opposite the position between the two bends, so that the high-temperature flue gas flows out of the flue gas channel and is quickly and directly sent out through the through-hole. Alternatively, the high-temperature flue gas in the back-fire area of the main heat exchange zone flows into the flue gas channel through the through-hole and is then sent into the superheated zone, thereby improving the heat exchange effect. The through holes may be strip-shaped through holes.

[0064] See also Figure 3As shown, the superheating zone 6 is provided with a plurality of inner guide plates 18. The sides of each inner guide plate 18 are connected to or in contact with the sides of adjacent inner guide plates 18. Each inner guide plate 18 is disposed directly opposite a heat exchange tube 2. The inner guide plates 18 are connected to the fins 13 or the heat exchange tubes 2. (If the heat exchange tubes are bare tubes, the inner guide plates may only be in contact with the heat exchange tubes at their edges, or may be in contact with the heat exchange tubes via support rods, as long as this does not affect the entry of flue gas from outside the superheating zone into the superheating zone.) The inner guide plates are provided with through holes, which are strip-shaped through holes. The installation structure of the inner guide plate is similar to or the same as that of the outer guide plate. It can be connected to the fins or directly connected to the heat exchange tubes. In this way, the distribution of the flue gas flow field can be optimized according to the heat exchange intensity required by different areas (liquid phase area, gas-liquid two-phase mixing area and vapor state area). For the liquid phase area, the heat exchange intensity of the flue gas can be enhanced. For the gas-liquid two-phase mixing area or the transition area (the connection between the gas-liquid two-phase mixing area and the liquid phase area is the transition area, and the connection between the gas-liquid two-phase mixing area and the vapor state area is also the transition area), the heat exchange intensity of the flue gas can be reduced or increased, thereby adjusting the flue gas convection heat exchange according to the steam and liquid positions in the heat exchange tubes, avoiding excessive heat exchange intensity in local areas, and improving the service life of the heat exchange tubes.

[0065] The through-hole size in the vapor zone is larger than that in the liquid zone, and the through-hole size in the liquid zone is larger than that in the vapor-liquid two-phase mixing zone. In this way, since the temperature of the high-temperature flue gas entering the superheated zone is not very high, and the temperature required in the vapor zone is not particularly high, and the heat transfer performance of the vapor state is relatively poor, the through-hole size in this area is the largest, and the required heat exchange effect can be the lowest. The flue gas temperature in the liquid zone itself is high, and the liquid phase has the best heat transfer performance, so its heat transfer effect can be set higher, so the through-holes in this area can be set slightly smaller. The through-holes in the vapor-liquid two-phase mixing zone are the smallest. Since this area has both liquid and vapor states, but is not pure liquid, its heat transfer performance is worse than that of pure liquid, but better than that of vapor. Since part of the vapor-liquid two-phase mixing zone is located within the main heat exchange zone, the high-temperature flue gas temperature in the partial vapor-liquid two-phase mixing zone in the main heat exchange zone is consistent with the high-temperature flue gas temperature in the liquid phase zone, and the heat transfer effect of the vapor-liquid two-phase mixing zone is worse than that of the liquid phase zone. Therefore, in order to protect the heat exchange tubes in the vapor-liquid two-phase mixing zone and prevent damage to the heat exchange tubes there, the through-holes in the vapor-liquid two-phase mixing zone are set to the smallest size, which can reduce the heat exchange intensity and thus protect the heat exchange tubes (since the high-temperature flue gas temperature in the liquid phase zone and part of the vapor-liquid two-phase mixing zone is consistent, the through-hole size in the vapor-liquid two-phase mixing zone is smaller, so the high-temperature flue gas flow rate in the vapor-liquid two-phase mixing zone will be smaller, thereby reducing the heat exchange intensity of the heat exchange tubes in the vapor-liquid two-phase mixing zone and protecting the heat exchange tubes in the vapor-liquid two-phase mixing zone). Of course, the through-hole sizes at each position can also be consistent.

[0066] See also Figure 3 、 6 As shown, each heat exchange tube 2 is further provided with a disturbance embedded tube 19, which is arranged in the vapor zone 12, and a distance is provided between the outer surface of the disturbance embedded tube 19 and the inner surface of the heat exchange tube 2 (the outer surface of the disturbance embedded tube can be provided with multiple rods connected to the inner wall of the heat exchange tube, or the top of the disturbance embedded tube can be connected to the steam header to achieve the fixation of the disturbance embedded tube, or other fixing methods can be used);

[0067] The disturbance embedded tube 19 is coaxially arranged with the heat exchange tube 2 .

[0068] Since the steam in the vapor zone mainly exchanges heat by convection, there is no need to consider the temperature difference between the inside and outside of the heat exchange tube. Therefore, a disturbance embedded tube is set in the vapor zone, which can reduce the volume of the vapor zone. At the same time, the internal steam contacts the inner wall of the heat exchange tube as much as possible, thereby improving the convection heat transfer effect, thereby increasing the steam dryness, or raising it to a slightly superheated state.

[0069] See also Figure 3 、 6 As shown, the heat exchange tube 2 is arranged vertically, the bottom of the heat exchange tube 2 is a water inlet 8, and the top of the heat exchange tube 2 is a steam outlet 9; the bottom and top of the furnace 1 are respectively provided with a water inlet header 20 and a steam header 21, the water inlet 8 at the bottom of the heat exchange tube 2 is connected to the water inlet header 20, and the steam outlet 9 at the top of the heat exchange tube 2 is connected to the steam header 21.

[0070] In this method, external water is fed into the water inlet header, which then supplies water to all heat exchange tubes simultaneously. This ensures that the liquid levels in all heat exchange tubes are consistent or nearly consistent, allowing precise control of the flow rate through the heat exchange tubes to accurately guarantee steam quality. The steam from all heat exchange tubes is then fed into the steam header, where it is collected and then delivered together. This allows the steam from all heat exchange tubes to be delivered together through a single pipeline.

[0071] The top of the steam header 21 is provided with a steam exhaust port 22, and a steam-water separation plate 23 is provided inside the steam header 21. The steam-water separation plate 23 is arranged between the steam exhaust port 22 and the steam outlet 9;

[0072] The steam-water separation plate is a multi-stage steam-water separation plate.

[0073] In this embodiment, the steam-water separation plate is a two-stage steam-water separation plate, wherein the two-stage steam-water separation plate includes a first-stage steam-water separation plate 24 and a second-stage steam-water separation plate 25. The first-stage steam-water separation plate adopts a mesh plate structure, which can separate the liquid water in the steam. The second-stage steam-water separation plate adopts a steam-water baffle structure, which uses the centrifugal force of the steam flow to further separate the water in the steam and improve the steam dryness.

[0074] See also Figure 1 、 2 As shown in Figures 4 and 5, a condensing heat exchanger 26 is further provided beside the furnace 1, and a plurality of rows of condensing side heat exchange tubes arranged at intervals are provided in the condensing heat exchanger 26.

[0075] The superheating zone 1 is provided with a first smoke exhaust port 7. The first smoke exhaust port and the heat insulation component are respectively provided at both ends of the superheating zone. One end of the first smoke exhaust port 7 is connected to the smoke inlet of the condensing heat exchanger 26, and the other end of the first smoke exhaust port 7 is connected to the superheating zone 6. In this embodiment, a hole can be provided in the middle of the steam header, which constitutes the first smoke exhaust port. The bottom of the hole is connected to the superheating zone, and the top is connected to the condensing heat exchanger. The medium-temperature flue gas after heat exchange in the superheating zone (the high-temperature flue gas after passing through the superheating zone and exchanging heat with the heat exchange tubes in the superheating zone, after the temperature drops, becomes medium-temperature flue gas) is sent out from the first smoke exhaust port and enters the condensing heat exchanger to exchange heat with the condensing-side heat exchange tubes in the condensing heat exchanger.

[0076] The condensing heat exchanger 26 is provided with a smoke exhaust pipe 27, and the smoke inlet and the smoke exhaust pipe 27 of the condensing heat exchanger 26 are respectively arranged on both sides of the condensing side heat exchange tube (the liquid inlet and the smoke exhaust pipe are respectively arranged on the upper side and the lower side of the condensing side heat exchange tube, or on the left side, right side, or front side, rear side).

[0077] In this embodiment, the smoke inlet of the condensing heat exchanger is arranged at its top, and the smoke exhaust pipe is arranged on the side below it. The smoke inlet is connected to the first smoke exhaust port through a pipe. The condensing side heat exchange pipe is designed for multi-return water circulation. The inlet of the condensing side heat exchange pipe is connected to an external water source. The outlet of the condensing side heat exchange pipe can be connected to an external pipe alone, or it can be connected to the inlet of the water inlet manifold. Preferably, it is connected to the inlet of the water inlet manifold. After the medium-temperature flue gas passes through the condensing side heat exchange pipe, it is discharged from the smoke exhaust pipe. In this way, the water in the condensing side heat exchange pipe can be heated or preheated by the medium-temperature flue gas whose temperature is not particularly high, and then the heated water is sent to the water inlet manifold, and then sent to the heat exchange pipe, so that it can be heated and vaporized more quickly, thereby saving energy consumption, reducing costs, and improving energy utilization.

[0078] At the same time, in the present invention, by adopting the arrangement of the heat insulation component, the condensing steam boiler can be arranged to be as small as possible, making the equipment more miniaturized.

[0079] In the description of the present invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

[0080] In the present invention, unless otherwise clearly specified or limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For example, the two can form a mechanical abutment or abutment connection through abutment, contact, etc. The two can also be directly hung or hung through an intermediate medium, etc., or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A condensing steam boiler comprising a furnace and a plurality of heat exchange tubes disposed in the furnace, wherein the plurality of heat exchange tubes are arranged in a ring to form a heat exchange tube loop, characterized in that: One end of the heat exchange tube is a water inlet, and the other end is a steam outlet. The medium in the heat exchange tube from the water inlet to the steam outlet is respectively a liquid phase zone, a vapor-liquid two-phase mixing zone, and a vapor state zone. A heat insulation component is provided on the inner side of the heat exchange tube coil. The heat insulation component is arranged on the inner side of the heat exchange tube coil at the vapor-liquid two-phase mixing zone. The heat insulation component separates the heat exchange tube coil into a main heat exchange zone and a superheating zone. The main heat exchange zone is a combustion zone, and the superheating zone is a secondary heat exchange zone for high-temperature flue gas. The liquid phase zone is arranged at the main heat exchange zone, the vapor phase zone is arranged at the superheat zone, and the vapor-liquid two-phase mixing zone is arranged at the connection between the main heat exchange zone and the superheat zone; The water inlet is provided on one side of the main heat exchange zone, and the steam outlet is provided on one side of the superheat zone. The liquid medium enters the heat exchange tube through the water inlet, is heated into a vapor state in the main heat exchange zone and the superheat zone, and then is discharged from the steam outlet. The outer surface of the heat insulation component abuts against the inner surface of the heat exchange tube ring; A plurality of outer guide plates are further provided on the outside of the heat exchange tube ring, the side of each outer guide plate being connected to or in contact with the side of an adjacent outer guide plate, each outer guide plate being arranged opposite a heat exchange tube, and the outer guide plates being connected to the heat exchange tube; And / or, a plurality of inner guide plates are provided in the superheating zone, the side of each inner guide plate is connected to or contacts the side of the adjacent inner guide plate, each inner guide plate is arranged opposite a heat exchange tube, and the inner guide plate is connected to the heat exchange tube.

2. The condensing steam boiler according to claim 1, characterized in that: A plurality of fins are arranged at intervals on the outer surface of each heat exchange tube, and the plurality of fins are arranged along the extending direction of the heat exchange tube.

3. The condensing steam boiler according to claim 2, characterized in that: The fins are provided with bends on opposite sides, respectively, and the bends abut against the bends of the adjacent upper or lower fins, so that the outside of the heat exchange tube between the two adjacent fins forms a flue gas channel; And / or, the side of the fin on each heat exchange tube contacts the side of the fin on the adjacent heat exchange tube, or the side of the fin on each heat exchange tube is arranged close to the side of the fin on the adjacent heat exchange tube.

4. The condensing steam boiler according to claim 3, characterized in that: One bent end of the fin at the main heat exchange area is arranged on the outside of the heat exchange tube coil.

5. The condensing steam boiler according to claim 3, characterized in that: One bent end of the fin at the superheating zone is arranged on the outside of the heat exchange tube coil; And / or, the other bent end of the fin at the superheating zone is arranged on the inner side of the heat exchange tube coil.

6. The condensing steam boiler according to claim 1, characterized in that: The outer guide plate and the inner guide plate are respectively provided with through holes.

7. The condensing steam boiler according to claim 6, characterized in that: The through-hole size in the vapor phase region is larger than the through-hole size in the liquid phase region, and the through-hole size in the liquid phase region is larger than the through-hole size in the vapor-liquid two-phase mixing region.

8. The condensing steam boiler according to claim 1, characterized in that: Each of the heat exchange tubes is further provided with a disturbance embedded tube, the disturbance embedded tube is arranged in the vapor zone, and there is a distance between the disturbance embedded tube and the inner wall of the heat exchange tube; And / or, the disturbance embedded tube is coaxially arranged with the heat exchange tube.

9. The condensing steam boiler according to claim 1, characterized in that: The heat exchange tube is arranged vertically, the bottom of the heat exchange tube is a water inlet, and the top of the heat exchange tube is a steam outlet; And / or, a water inlet header and a steam header are respectively provided at the bottom and top of the furnace, the water inlet at the bottom of the heat exchange tube is connected to the water inlet header, and the steam outlet at the top of the heat exchange tube is connected to the steam header.

10. The condensing steam boiler according to claim 9, characterized in that: The top of the steam header is provided with a steam exhaust port, and a steam-water separation plate is provided inside the steam header, and the steam-water separation plate is arranged between the steam exhaust port and the steam outlet; And / or, the steam-water separation plate is a multi-stage steam-water separation plate.

11. The condensing steam boiler according to claim 1, characterized in that: A condensing heat exchanger is also provided beside the furnace, and a plurality of rows of condensing side heat exchange tubes arranged at intervals are provided in the condensing heat exchanger; A first smoke exhaust port is provided on the superheating zone, and the first smoke exhaust port is connected to the smoke inlet of the condensing heat exchanger; The condensing heat exchanger is provided with a smoke exhaust pipe, and the smoke inlet and the smoke exhaust pipe are respectively arranged on the upper and lower sides of the condensing side heat exchange pipe.

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