Pipe heating furnace with rich waste heat utilization

Abstract

The utility model provides a kind of tubular heating furnace of rich waste heat utilization, comprising: for realizing kerosene heating furnace body, heat recovery device for recovering flue gas waste heat is equipped in furnace body, heat recovery device includes: total water inlet pipeline is located at inlet pipe mouth;For receiving low-temperature water source introduced by total water inlet pipeline and realizing water flow preliminary distribution first annular pipeline, with the first annular pipeline connection and with the first annular pipeline axis as center according to circular track equidistant arrangement several longitudinal water inlet pipeline;Radial flow divider is connected to the water outlet of longitudinal water inlet pipeline lower end, multilayer heat exchange assembly is connected to the water outlet one end of radial flow divider;Converging transport component is equipped in outlet pipe mouth and heat exchange assembly connection. By setting radial flow divider and multilayer heat exchange assembly, water flow direction multilayer heat exchange assembly, improve water flow velocity, and then improve heat absorption efficiency, while multilayer heat exchange assembly covers the radial range of flue gas passage, improve space utilization, make waste heat recovery more fully.

Description

Technical Field

[0001] This utility model relates to the field of waste heat recovery and utilization technology, specifically to a tubular heating furnace for utilizing surplus waste heat. Background Technology

[0002] Tubular furnaces are core heating equipment commonly used in petrochemical, coal chemical and other industrial fields. In the conventional operation of a tubular furnace, the burner at the bottom of the furnace releases heat through fuel combustion, heating the kerosene and other media flowing in the furnace tubes to the required process temperature (usually 200~400℃). During the combustion process, a large amount of high-temperature flue gas with a temperature as high as 300~500℃ is generated. Currently, the industry generally adopts the "direct emission" mode, that is, the high-temperature flue gas directly enters the tail gas treatment equipment through the chimney at the top of the tubular furnace, resulting in a large amount of heat source loss.

[0003] Some systems use pipe heat exchangers, which are simple heat exchange devices installed at the chimney. These devices use a single row of S-shaped coiled pipes, which can only cover a local area of ​​the flue gas wall and cannot cover the entire flue gas flow cross section. This creates a large number of heat exchange dead zones in some areas, resulting in insufficient waste heat recovery. Furthermore, the S-shaped pipes have unidirectional flow, and for the same unit area, unidirectional flow can only achieve a lower temperature for heat exchange, resulting in insufficient waste heat recovery. To increase the heat exchange temperature, it is necessary to increase the flow velocity inside the pipe, the inner diameter of the pipe, and multiple S-shaped pipes, which would result in higher costs compared to not using heat exchangers. If conventional heat exchangers are used, the narrow flow channels are prone to blockage, leading to frequent cleaning and making cleaning difficult. Utility Model Content

[0004] This utility model provides a tubular heating furnace for utilizing surplus waste heat, in order to solve the problem of insufficient waste heat recovery in the prior art.

[0005] To address the aforementioned problems, this utility model provides a tubular heating furnace for utilizing surplus waste heat, comprising: a furnace body for heating kerosene, a chimney at the top of the furnace body for discharging flue gas, a heat exchange device below the chimney for recovering waste heat from the flue gas, and an inlet and outlet pipe on the furnace body wall for introducing low-temperature water into the heat exchange device and leading out the water after heat exchange; the heat exchange device includes: a main water inlet pipe located at the inlet pipe; a first annular pipe for receiving the low-temperature water introduced from the main water inlet pipe and achieving preliminary water flow distribution; a plurality of longitudinal water inlet pipes connected to the first annular pipe and arranged at equal intervals along a circular trajectory centered on the axis of the first annular pipe; a radial flow divider connected to the outlet at the lower end of the longitudinal water inlet pipes; a multi-layer heat exchange assembly connected to one end of the outlet of the radial flow divider; and a confluence conveying assembly located at the outlet pipe and connected to the heat exchange assembly.

[0006] By setting up radial flow dividers and multi-layer heat exchange components, the water flow is diverted to the multi-layer heat exchange components, increasing the water flow velocity. Multi-layer heat exchange allows low-temperature water to fully exchange heat with high-temperature flue gas, improving heat absorption efficiency. At the same time, the multi-layer heat exchange components cover the radial range of the flue gas channel, avoiding the flue gas bypass and heat exchange dead zone problems that exist in traditional single-row pipes, improving space utilization, making waste heat recovery more complete, and connecting the hot water outlet pipe of the heat exchange device with other process heating equipment to reduce production operating costs.

[0007] To address the issues of low flow velocity, small heat transfer coefficient, and insufficient heat exchange in traditional unidirectional coils, the aforementioned radial flow divider is further modified to be a multi-port steel pipe, with its upper end connected to the lower end of the longitudinal inlet pipe. This allows the low-temperature water source to flow from the longitudinal inlet pipe into the multi-port steel pipe and then be simultaneously distributed to other channels, effectively increasing the flow velocity, thereby improving the heat transfer coefficient, enhancing the heat exchange effect, and preventing some heat exchange units from becoming idle due to uneven distribution.

[0008] To address the issues of insufficient waste heat recovery caused by flue gas bypass and heat exchange dead zones in traditional single-row coils, the aforementioned heat exchange assembly further includes multi-layered inner and outer heat exchange units arranged inside and outside the longitudinal water inlet pipe.

[0009] To avoid clogging of traditional heat exchangers by impurities in the flue gas, which would reduce heat exchange efficiency, preferably, both the inner and outer heat exchange units consist of upper and lower second annular pipes and longitudinal heat exchange pipes arranged at equal intervals along a circular trajectory between the upper and lower second annular pipes. The two ends of the longitudinal heat exchange pipes are connected to the upper and lower second annular pipes respectively. These multi-layered inner and outer heat exchange units cover the entire radial range of the flue gas passage, ensuring full contact between the high-temperature flue gas and the heat exchange units, significantly improving waste heat recovery efficiency and making waste heat recovery more complete. Furthermore, the equal-interval arrangement provides sufficient gaps between the pipes, reducing the risk of clogging. Compared to plate heat exchangers, the pipe structure is easier to clean and maintain, reducing maintenance costs.

[0010] To address the low heat exchange efficiency of traditional unidirectional S-shaped coils, and the stratification phenomenon (slower flow velocity in the upper layer and faster flow velocity in the lower layer due to gravity) in multi-bend unidirectional S-shaped pipes, which leads to insufficient heat exchange in localized areas and creates heat exchange dead zones, a preferred embodiment is proposed where the aforementioned multi-layered inner and outer heat exchange units are connected to the lower second annular pipe via radially connecting pipes. Multiple second annular pipes 351 are connected in series, with the inner and outer heat exchange unit groups independently connected and not interfering with each other. This allows water to fill the longitudinal pipes from bottom to top, avoiding empty pipes and localized overheating, and improving heat exchange uniformity.

[0011] To further facilitate the collection of hot water from multiple heat exchange units after heat exchange, the aforementioned collection and conveying assembly includes a third annular pipe and several collection and conveying branches connecting the third annular pipe and the heat exchange assembly. By setting up these collection and conveying branches, the longitudinal heat exchange pipes in each heat exchange unit can have sufficient contact time with the high-temperature flue gas, resulting in a stable water temperature after heat exchange. In existing conveying devices, hot water and steam are transported together, which can easily result in "water vapor carryover," hindering the use of subsequent equipment. Therefore, the aforementioned third annular pipe is equipped with a water-vapor separation unit, and a steam outlet is located on the third annular pipe. The water-vapor separation unit separates steam and hot water, facilitating the use of subsequent equipment.

[0012] The technical advantages of this application are as follows: (1) By using the horizontal radial pipe diversion structure, combined with the internal and external multi-layer heat exchange units, the water flow velocity is significantly improved, avoiding the risk of scaling caused by water flow stagnation. At the same time, the longitudinal heat exchange pipes set in the multi-layer heat exchange units enable the cold water and high-temperature flue gas to exchange heat fully, thereby improving the heat absorption efficiency. (2) The arrangement of the inner and outer multi-layer heat exchange units basically covers the radial range of the flue gas channel, avoiding the problems of flue gas bypass and heat exchange dead angle that exist in traditional single-row pipes.

[0013] (3) The setting of the confluence and delivery component extends the residence time of water in the longitudinal heat exchange pipe, and the waste heat recovery is more thorough. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of a tubular heating furnace for utilizing surplus waste heat, provided by this utility model.

[0015] Figure 2 This is a side sectional view of the heat exchange device of a tubular heating furnace for utilizing surplus heat, provided by this utility model.

[0016] Figure 3 This is a schematic diagram of the hot water flow direction of a tubular heater for utilizing surplus waste heat, provided by this utility model.

[0017] Explanation of reference numerals in the attached figures: 1. Furnace body; 110. Inlet pipe; 120. Outlet pipe; 2. Chimney; 3. Heat exchange device; 310. Main water inlet pipe; 320. First annular pipe; 330. Longitudinal water inlet pipe; 340. Radial branch pipe; 350. Heat exchange assembly; 351. Second annular pipe; 352. Longitudinal heat exchange pipe; 360. Combination and conveying assembly; 361. Third annular pipe; 362. Combination and conveying branch; 363. Steam outlet. Detailed Implementation

[0018] The following will be combined with the appendix Figures 1-3 The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0019] Tubular furnaces are core heating equipment commonly used in petrochemical, coal chemical, and other industrial sectors. In the conventional operation of a tubular furnace, the burner at the bottom releases heat through fuel combustion, heating the kerosene or other media flowing inside the furnace tubes to the required process temperature (typically 200-400℃). This combustion process generates a large amount of high-temperature flue gas, reaching 300-500℃. Currently, the industry commonly uses a "direct emission" mode, where the high-temperature flue gas is directly discharged into the atmosphere through the chimney at the top of the tubular furnace. Some systems use convection pipes below the outlet for heat exchange, but these pipes have unidirectional flow and low heat exchange efficiency. If heat exchangers are used, their narrow flow channels are prone to blockage, leading to frequent and difficult cleaning.

[0020] To solve the above problems, refer to Figures 1-3 This utility model provides a tubular heating furnace for utilizing surplus heat. The furnace body 1 is used to heat kerosene. The top of the furnace body is provided with a chimney 2 for exhausting flue gas. Below the chimney is a heat exchange device 3 for recovering the waste heat of the flue gas. The furnace body wall is provided with an inlet 110 and an outlet 120 for introducing a low-temperature water source into the heat exchange device and leading out the water source after heat exchange. The heat exchange device 3 includes: a main water inlet pipe 310 located at the inlet 110; a first annular pipe 320 for receiving low-temperature water introduced from the main water inlet pipe 310 and achieving preliminary water flow distribution; a plurality of longitudinal water inlet pipes 330 connected to the first annular pipe 320 and arranged at equal intervals along a circular trajectory with the axis of the first annular pipe 320 as the center; a radial flow divider 340 connected to the outlet at the lower end of the longitudinal water inlet pipes 330; a multi-layer heat exchange assembly 350 connected to one end of the outlet of the radial flow divider 340 for contact heat exchange with high-temperature flue gas; and a confluence conveying assembly 360 located at the outlet 120 and connected to the heat exchange assembly 350.

[0021] By setting up a radial flow divider 340 and a multi-layer heat exchanger 350, the water flow is diverted to the multi-layer heat exchanger 350, increasing the water flow velocity. The multi-layer heat exchange allows the low-temperature water and high-temperature flue gas to exchange heat fully, improving the heat absorption efficiency. At the same time, the multi-layer heat exchanger 350 covers the radial range of the flue gas channel, avoiding the flue gas bypass and heat exchange dead zone problems that exist in traditional single-row pipes, improving space utilization, making waste heat recovery more complete, and connecting the hot water outlet pipe of the heat exchanger 3 to other process heating equipment to reduce production operating costs.

[0022] To adapt to environments with high flue gas temperatures and potentially corrosive components, all heat exchange devices 3 in this application are made of high-temperature and corrosion-resistant stainless steel. The diameter of the main inlet water pipe 310 is determined based on the overall water flow requirements of the heat exchange device 3, such as through calculations based on heat exchange capacity, mass flow rate, and economic flow rate. The main inlet water pipe 310 and the inlet 110 can be connected by a flange for easy installation, disassembly, and maintenance. A filter can be installed on the main inlet water pipe to filter impurities in the low-temperature water, preventing impurities from entering subsequent pipes and heat exchange components and causing blockages. The filtration precision is selected according to the actual situation.

[0023] The first annular pipe 320 is circular to facilitate connection with the longitudinal water inlet pipe 330 at equal intervals. The number of openings is the same as the number of longitudinal water inlet pipes 330, and the diameter of the openings matches the inner diameter of the longitudinal water inlet pipe 330 to ensure smooth water flow into the longitudinal water inlet pipe 330.

[0024] The number of longitudinal inlet pipes 330 is determined based on the heat exchange area requirements of the heat exchange device and the radial dimensions of the flue gas passage, so that the subsequent heat exchange assembly 350 can cover the entire radial range. The length of the longitudinal inlet pipes 330 must be longer than the length of the longitudinal transmission pipes 352 of the heat exchange assembly 350, and the bottom installation height should be consistent with the bottom of the heat exchange assembly 350 to match the radial flow divider 340.

[0025] In order to control the flow rate in the heat exchange device 3, a delivery pump can be installed at the inlet 110. The delivery pump can be installed in a conventional manner used by those skilled in the art to control the flow rate.

[0026] Furthermore, to address the issues of low flow velocity, small heat transfer coefficient, and insufficient heat exchange in traditional unidirectional coils, the radial diverter 340 provided in this embodiment is a multi-port steel pipe. Its upper end is connected to the lower end of the longitudinal inlet pipe 330, and a three-way steel pipe can be used. This allows the low-temperature water source to flow from the longitudinal inlet pipe 330 into the three-way steel pipe and then be simultaneously diverted to both radial sides, effectively increasing the flow velocity and thus improving the heat transfer coefficient and enhancing the heat exchange effect. At the same time, it provides a uniform and stable water supply for the subsequent multi-layer heat exchange components 350, ensuring that each heat exchange unit can fully participate in heat exchange, avoiding the idleness of some heat exchange units due to uneven distribution, and improving the overall heat exchange efficiency of the heat exchange system.

[0027] In addition to the aforementioned three-way steel pipe, a four-way steel pipe structure can also be used, allowing for flow splitting at both the lower end and the radial left and right ends. Multi-way distributors can also be employed, increasing the number of flow splitting channels based on the number and distribution of heat exchange units, providing flexibility and uniformity in distribution, thereby improving heat exchange efficiency.

[0028] To address the issues of insufficient waste heat recovery caused by flue gas bypass and heat exchange dead zones in traditional single-row coil heat exchangers, the heat exchange assembly 350 provided in this embodiment includes a multi-layer inner heat exchange unit arranged inside the longitudinal water inlet pipe 330 and a multi-layer outer heat exchange unit arranged outside the longitudinal water inlet pipe 330. The multi-layer inner and outer heat exchange units cover the entire radial range of the flue gas passage, ensuring full contact between the high-temperature flue gas and the heat exchange assembly 350, significantly improving waste heat recovery efficiency and making waste heat recovery more complete. Furthermore, the equally spaced arrangement of the pipes provides sufficient clearance, reducing the risk of blockage. Compared to plate heat exchangers, the pipe structure is easier to clean and maintain, reducing maintenance costs.

[0029] To avoid clogging of traditional heat exchangers by impurities in flue gas, which would reduce heat exchange efficiency, the internal and external heat exchange units provided in this embodiment both consist of upper and lower second annular pipes 351 and longitudinal heat exchange pipes 352 arranged at equal intervals along a circular trajectory between the upper and lower second annular pipes 351. The two ends of the longitudinal heat exchange pipes 352 are connected to the upper and lower second annular pipes 351, respectively. The number and diameter of the longitudinal heat exchange pipes 352 are determined by comprehensively considering heat exchange efficiency, water flow resistance, the circumference of the second annular pipes 351, and the spacing. To achieve efficient heat exchange, their diameter must be smaller than the diameter of the longitudinal inlet pipe 330.

[0030] To address the low heat exchange efficiency of traditional unidirectional S-shaped coils, and the stratification phenomenon caused by gravity in multi-bend unidirectional S-shaped pipes (where the upper layer has a slower flow velocity and the lower layer a faster flow velocity), leading to insufficient heat exchange in localized areas and creating heat exchange dead zones, this embodiment, as a preferred implementation, connects the multi-layered inner and outer heat exchange units to the lower second annular pipe 351 via radially connecting pipes. Multiple second annular pipes 351 are connected in series, with the inner and outer heat exchange unit groups independently connected and not interfering with each other. This allows water to flow upwards into the longitudinal pipes, preventing localized overheating and improving heat exchange uniformity. Simultaneously, one-way valves (such as check valves) can be installed on the radially connecting pipes to adjust the water flow velocity according to changes in flue gas and discharge water temperature, preventing reverse flow. Several stainless steel supports are also provided at the bottom of the lower second annular pipe 351, connected to the furnace wall via brackets to support the overall structure of the heat exchange device 3.

[0031] Furthermore, the flow distribution assembly 360 provided in this embodiment includes a third annular pipe 361 and several flow distribution branches 362 connecting the third annular pipe 361 and the heat exchange assembly 350. The two ends of each flow distribution branch 362 are connected to the third annular pipe 361 and the upper second annular pipe 353, respectively. The hot water from each heat exchange assembly 350 is collected into the third annular pipe 361 through the flow distribution branches 362, ensuring uniform flow and avoiding localized flow concentration or pressure fluctuations. The diameter of the third annular pipe 361 must be larger than the diameters of the first annular pipe 320 and the second annular pipe 353 to meet the requirements for the total flow rate of the water after heat exchange. Each heat exchange unit needs to be equipped with no fewer than four flow distribution branches 362. Because the water flow rate in the heat exchange unit is large while the flow rate in the flow distribution branches is small, the water flows for a long time in the heat exchange unit, allowing sufficient contact time between the longitudinal heat exchange pipe 354 in each heat exchange unit and the high-temperature flue gas, resulting in a stable water temperature after heat exchange.

[0032] In existing conveying devices, hot water and steam are mixed during transport, which easily leads to "water vapor carryover," which is detrimental to the use of subsequent equipment. Therefore, the third annular pipe 361 provided in this embodiment is also equipped with a water vapor separation unit 363 to achieve effective separation of hot water and steam. The third annular pipe 361 is equipped with a steam outlet 363. The water vapor separation unit 363 is a conventional water vapor separation method commonly used by those skilled in the art. The water vapor separation unit 363 can be a baffle plate type. When water flows through the baffle plate, due to inertia, the hot water hits the baffle plate and falls, while the steam continues to rise, achieving separation. A safety valve (illustrated in the figure) is provided at the top of the steam outlet 363. When the steam pressure is too high and exceeds the design pressure, the safety valve automatically opens to release pressure, preventing the steam outlet 363 and the pipe from rupturing due to overpressure, thus protecting the system safety. After the pressure drops to the design pressure after pressure release, the safety valve automatically closes, restoring normal operation.

[0033] Working principle: When the burner at the bottom of the furnace 1 burns fuel, the resulting high-temperature flue gas flows upward and eventually needs to be discharged through the top chimney 2. The heat exchange device 3 is arranged in the flue gas channel below the chimney, and its multi-layer heat exchange components 350 are directly in the flow path of the high-temperature flue gas, providing a direct environment for heat transfer. The specific heat exchange process is as follows: See attached document Figure 3 The low-temperature water source first enters the main water inlet pipe 310 of the heat exchange device 3 through the inlet pipe 110 on the furnace wall. The low-temperature water will first pass through a filter to remove impurities to avoid blockage of subsequent pipes. Subsequently, the low-temperature water flows into the first annular pipe 320 connected to the main water inlet pipe 310. The low-temperature water flows along the annular path and is sequentially distributed to each longitudinal water inlet pipe 330 that is equidistantly connected to the first annular pipe 320.

[0034] The low-temperature water in the longitudinal inlet pipe 330 flows downward and enters the radial diversion component 340 (preferably a three-way steel pipe) connected at its lower end. The low-temperature water is simultaneously diverted to both radial sides here, which not only increases the flow path and coverage of the water per unit time, but also provides a stable water source for the subsequent multi-layer heat exchange components, avoiding some heat exchange units from being idle.

[0035] After being diverted by the radial diverter 340, the low-temperature water enters the multi-layer heat exchange assembly 350. The low-temperature water first flows into the lower second annular pipe 351 and then is distributed to each longitudinal heat exchange pipe 352. Since the multi-layer inner and outer heat exchange units are connected in series by radial connecting pipes, the water flows from bottom to top along the path of "lower second annular pipe 351 - adjacent unit lower second annular pipe 351 - longitudinal heat exchange pipe 352 - upper second annular pipe 351", avoiding local overheating.

[0036] During the flow of water, it undergoes complete heat exchange with high-temperature flue gas. The hot water that has completed the heat exchange enters from the upper second annular pipe 351 of each heat exchange unit and is then collected into the third annular pipe 361 via the confluence transport branch 362. The third annular pipe 361 is equipped with a water-steam separation unit 363 to achieve effective separation of hot water and steam. The separated hot water is transported to other process equipment that needs to be heated through the outlet 120 on the wall of the furnace body 1, while the separated steam is discharged from the steam outlet 363 of the third annular pipe 361. The safety valve at the top of the outlet can automatically release pressure when the steam pressure exceeds the limit to ensure system safety.

[0037] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A tubular heater for utilizing surplus waste heat, comprising: The furnace body (1) is used to realize kerosene heating. The top of the furnace body (1) is provided with a chimney (2) for exhausting flue gas. Below the chimney (2) is a heat exchange device (3) for recovering waste heat from the flue gas. The furnace body (1) wall is provided with an inlet (110) and an outlet (120) for introducing low-temperature water into the heat exchange device (3) and drawing out the water after heat exchange. The heat exchange device (3) is characterized in that it includes a main water inlet pipe (310) located at the inlet pipe (110). A first annular pipe (320) for receiving the low-temperature water source introduced by the main water inlet pipe (310) and realizing the initial distribution of water flow, and a number of longitudinal water inlet pipes (330) connected to the first annular pipe (320) and arranged at equal intervals in a circular trajectory with the axis of the first annular pipe (320) as the center. A radial flow divider (340) is connected to the outlet at the lower end of the longitudinal water inlet pipe (330), and a multi-layer heat exchange assembly (350) is connected to one end of the outlet of the radial flow divider (340). A manifold conveying assembly (360) is provided at the outlet (120) and connected to the heat exchange assembly (350).

2. The tubular heating furnace for utilizing surplus waste heat according to claim 1, characterized in that, The radial diverter (340) is a multi-port steel pipe, the upper end of which is connected to the lower port of the longitudinal water inlet pipe (330).

3. The tubular heating furnace for utilizing surplus waste heat according to claim 1, characterized in that, The heat exchange assembly (350) includes multiple layers of inner and outer heat exchange units arranged inside and outside the longitudinal water inlet pipe (330).

4. The tubular heating furnace for utilizing surplus waste heat according to claim 3, characterized in that, Both the inner and outer heat exchange units consist of upper and lower second annular pipes (351) and longitudinal heat exchange pipes (352) arranged at equal intervals in a circular trajectory between the upper and lower second annular pipes (351). The two ends of the longitudinal heat exchange pipes (352) are respectively connected to the upper and lower second annular pipes (351).

5. The tubular heating furnace for utilizing surplus waste heat according to claim 4, characterized in that, The multi-layer inner and outer heat exchange units are respectively connected to the lower second annular pipe (351) through radial connecting pipes.

6. The tubular heating furnace for utilizing surplus waste heat according to claim 1, characterized in that, The manifold assembly (360) includes a third annular pipe (361) and several manifold branches (362) connecting the third annular pipe (361) and the heat exchange assembly (350).

7. The tubular heating furnace for utilizing surplus waste heat according to claim 6, characterized in that, The third annular pipe (361) is also equipped with a water vapor separation unit, and the third annular pipe (361) is equipped with a steam outlet (363).

Images