Steel billet heating kiln with integrated high-temperature steam supply function and residual heat recovery device
By installing spiral finned high-temperature heat exchange tubes and a dynamic control system on the inner wall of the flue of the billet heating kiln, the problem of ineffective utilization of waste heat in the billet heating kiln was solved, achieving efficient waste heat recovery and improved equipment stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 武汉钢铁有限公司
- Filing Date
- 2025-05-28
- Publication Date
- 2026-05-26
AI Technical Summary
Existing billet heating kilns have low energy efficiency, and the waste heat from high-temperature flue gas is not effectively utilized, resulting in high heat loss rates and increased equipment complexity and renovation costs.
The waste heat recovery device, which integrates high-temperature steam supply, includes high-temperature heat exchange tubes, a softened water supply system, a variable frequency water pump, a steam-water separator, and a safety valve. It achieves efficient waste heat recovery by installing spiral finned high-temperature heat exchange tubes on the inner wall of the flue, and realizes dynamic control through controllers and sensors.
The waste heat recovery rate of flue gas was increased to 85%, the oxidation loss rate of steel billets and CO2 emissions were reduced, the equipment investment cost and energy consumption were reduced, and the stability and life of the equipment were improved.
Smart Images
Figure CN224285461U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of waste heat utilization technology of metallurgical flue gas, and in particular to a billet heating kiln with integrated high-temperature steam external supply function and a waste heat recovery device. Background Technology
[0002] As a core piece of equipment in the metallurgical industry, billet heating kilns play a crucial role in heating billets to the high temperatures (1100~1300℃) required for rolling or forging. However, their low energy efficiency and high carbon emissions have long been problems. Traditional kilns mostly rely on flue gas waste heat boilers to recover heat from waste gases. However, when the flue gas exits the furnace, its temperature has dropped significantly (usually <600℃), resulting in a heat loss rate as high as 30%~40%. Furthermore, independent waste heat boilers require additional floor space for installation, and the complexity of the equipment and the cost of modification limit their widespread application.
[0003] In existing technologies, the billet heating and energy recovery systems are disconnected from each other, and the direct waste heat of high-temperature flue gas (preheating section temperature 600~800℃) is not effectively utilized. Meanwhile, the independent steam generator still relies on fossil fuel combustion, resulting in insufficient overall energy efficiency and significant energy waste. Utility Model Content
[0004] The main purpose of this utility model is to provide a billet heating kiln with integrated high-temperature steam external supply function and a residual heat recovery device, which aims to improve the residual heat recovery efficiency on the one hand and extend its service life on the other.
[0005] To achieve the above objectives, this utility model provides a waste heat recovery device for a billet heating kiln with integrated high-temperature steam supply function, comprising a high-temperature heat exchange tube, a softened water supply system, a variable frequency water pump, a steam-water separator, and a first safety valve, wherein...
[0006] Spiral fins are welded to the outer wall of the high-temperature heat exchange tube. The high-temperature heat exchange tube is installed on the inner wall of the flue of the kiln. The outlet of the softened water supply system is connected to the inlet of the high-temperature heat exchange tube through a variable frequency water pump. The outlet of the high-temperature heat exchange tube is connected to the external steam network through a steam-water separator and a first safety valve.
[0007] Preferably, the fin height is 10-15mm, and the fin spacing along the length of the high-temperature heat exchange tube is 5mm-8mm.
[0008] Preferably, the inlet of the high-temperature heat exchange tube is located at the high-temperature end of the flue, and the outlet of the high-temperature heat exchange tube is located at the low-temperature end of the flue.
[0009] Preferably, the waste heat recovery device further includes a controller, which is electrically connected to the variable frequency water pump, the water separator and the first safety valve.
[0010] Preferably, the waste heat recovery device further includes a temperature sensor installed inside the kiln and a pressure transmitter installed inside a high-temperature heat exchange tube, and the controller is electrically connected to the temperature sensor and the pressure transmitter.
[0011] Preferably, the waste heat recovery device further includes an acoustic soot cleaner installed outside the high-temperature heat exchange tube to clean the ash accumulated on the fin surface.
[0012] Preferably, the waste heat recovery device further includes a water quality detector installed between the softened water supply system and the variable frequency water pump.
[0013] Preferably, the high-temperature heat exchange tube comprises multiple coils connected by flanges, and a second safety valve is installed at the end of each coil.
[0014] Preferably, a V-shaped refractory bracket is provided below the high-temperature heat exchange tube to support it; the high-temperature heat exchange tube has an outer diameter of 150mm~200mm and a wall thickness of 8mm~12mm.
[0015] This utility model also proposes a billet heating kiln with integrated high-temperature steam external supply function, including the above-mentioned waste heat recovery device, and also including the kiln body, on which a flue is provided.
[0016] The waste heat recovery device proposed in this utility model has the following beneficial effects:
[0017] 1. By recovering waste heat in situ (heat exchange tubes are installed on the inner wall of the flue instead of at the outlet), the comprehensive heat recovery rate of flue gas is improved, while reducing the oxidation loss rate of steel billets and CO2 emissions. It has low requirements for equipment materials, reduces investment costs, and is suitable for industrial energy-saving renovation in multiple scenarios such as steel rolling, forging and heat treatment.
[0018] 2. This waste heat recovery device uses a finned structure, which can improve heat exchange efficiency;
[0019] 3. This waste heat recovery device increases the comprehensive recovery rate of flue gas waste heat from 40% of traditional technology to over 85%, with a steam output of 6t / h (pressure 1.6MPa, temperature 250℃), while reducing energy consumption per ton of steel by 15% (natural gas consumption reduced by 1.5 million m³ / year).
[0020] 4. This waste heat recovery device has the advantages of simple structure and stable and reliable operation;
[0021] 5. By installing a safety valve, the risk of heat exchange tube rupture is reduced, and the lifespan of the heat exchange tube is increased. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of the billet heating kiln that integrates the function of external high-temperature steam supply according to this utility model.
[0023] In the diagram, 1-flue, 2-cold water inlet, 3-variable frequency water pump, 4-high temperature heat exchange tube, 5-second safety valve, 6-fins, 7-steam-water separator, 8-first safety valve, 9-temperature sensor, 10-pressure sensor, 11-controller, 12-softened water supply system, 13-external steam network, 14-water quality detector, 15-sonic soot remover.
[0024] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0025] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.
[0026] It should be noted that in the description of this utility model, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0027] This utility model proposes a waste heat recovery device for a billet heating kiln that integrates high-temperature steam external supply function.
[0028] Reference Figure 1 In this preferred embodiment, a waste heat recovery device for a billet heating kiln integrating high-temperature steam external supply function includes a high-temperature heat exchange tube 4, a softened water supply system 12, a variable frequency water pump 3, a steam-water separator 7, and a first safety valve 8.
[0029] Spiral fins 6 are welded to the outer wall of the high-temperature heat exchange tube 4. The high-temperature heat exchange tube 4 is installed on the inner wall of the flue 1 of the kiln. The outlet of the softened water supply system 12 is connected to the inlet of the high-temperature heat exchange tube 4 through the variable frequency water pump 3. The outlet of the high-temperature heat exchange tube 4 is connected to the external steam network 13 through the steam-water separator 7 and the first safety valve 8 in sequence.
[0030] The variable frequency water pump 3 uses variable frequency control, with a flow rate ≥2m / s and an inlet water temperature ≤50℃. In this embodiment, the fin height 6 is 10~15mm, and the spacing between the fins 6 along the length of the high-temperature heat exchange tube 4 is 5mm~8mm. The outer diameter of the high-temperature heat exchange tube 4 is 150mm~200mm, and the wall thickness is 8mm~12mm. The ratio of the fin pitch to the tube diameter is 1:1.5. In this embodiment, the high-temperature heat exchange tube 4 is a coil arranged along the flue gas flow direction. The coil structure can improve its heat exchange efficiency, thereby improving the utilization rate of flue gas heat energy.
[0031] In this embodiment, the inlet of the high-temperature heat exchange tube 4 is located at the high-temperature end of the flue 1, and the outlet of the high-temperature heat exchange tube 4 is located at the low-temperature end of the flue 1. This arrangement helps to improve the heat exchange efficiency of the heat exchange tube.
[0032] In this embodiment, the waste heat recovery device also includes a controller 11, which is electrically connected to the variable frequency water pump 3, the water separator and the first safety valve 8.
[0033] In this embodiment, the waste heat recovery device also includes a temperature sensor 9 installed inside the kiln and a pressure transmitter installed inside the high-temperature heat exchange tube 4. The controller 11 is electrically connected to the temperature sensor 9 and the pressure transmitter. Four sets of temperature sensors 9 are arranged along the billet conveying direction.
[0034] The surface temperature of the steel billet is monitored in real time by temperature sensor 9, and the steam pressure is collected by pressure transmitter and sent to controller 11. Controller 11 then adjusts the flow rate of variable frequency water pump 3 and the opening of first safety valve 8 and second safety valve 5 according to heat balance algorithm to maintain flue gas flow rate. When the flow rate is low, the valve is automatically closed to increase the flow rate and prevent ash accumulation; when the flow rate is high, the valve is opened to reduce resistance.
[0035] The accuracy of temperature sensor 9 and pressure sensor 10 is checked monthly (error ≤1%) and any faulty components are replaced.
[0036] Furthermore, this waste heat recovery device also includes an acoustic soot remover 15 installed outside the high-temperature heat exchange tube 4 to clean the dust accumulated on the surface of the fins 6. The acoustic soot remover 15 can be set to automatically trigger every 8 hours, with a transmission frequency of 80Hz~120Hz and a duration of 10 seconds, to shake off the dust accumulated on the surface of the fins 6.
[0037] Furthermore, this waste heat recovery device also includes a water quality detector 14 installed between the softened water supply system 12 and the variable frequency water pump 3. The water quality detector 14 monitors the water quality supplied by the softened water supply system 12 in real time, and promptly detects any changes in water quality. The conductivity of the softened water in the softened water supply system 12 is ≤10μS / cm.
[0038] In addition, the high-temperature heat exchange tube 4 includes multiple coils connected by flanges. A second safety valve 5 is installed at the end of each coil. The flange connection between the coils ensures sealing and allows for quick assembly and disassembly. The high-temperature heat exchange tube 4 includes multiple coils, which facilitates maintenance. When the seismic sensor and pressure sensor 10 detect abnormal internal pressure in the heat exchange tube, the second safety valve 5 automatically opens to drain moisture.
[0039] Furthermore, a V-shaped refractory bracket is installed below the high-temperature heat exchange tube 4 to support it. The V-shaped refractory bracket is made of silicon carbide ceramic, which is resistant to high temperatures of 1200℃ and can prevent the high-temperature heat exchange tube 4 from deforming due to thermal expansion. The inner wall of the high-temperature heat exchange tube 4 is cleaned with a high-pressure water jet of ≥20MPa every 3 months to control the scale thickness to ≤0.1mm.
[0040] The working process of this waste heat recovery device is as follows:
[0041] The softened water supply system 12 enters the high-temperature heat exchange tube 4 via a variable frequency water pump 3. The power of the variable frequency water pump 3 is controlled by a controller 11 to regulate the water flow. High-temperature flue gas passes through the water in the high-temperature heat exchange tube 4 via radiation and convection heat exchange. After heat exchange, the water inside the high-temperature heat exchange tube 4 becomes steam, which is then discharged through a steam-water separator 7. The steam dryness of the steam in the steam-water separator 7 is ≥95%, the operating pressure of the first safety valve 8 is 3.0 MPa, and the burst pressure of the rupture disc is 3.5 MPa. Steam at 1.6 MPa and 250°C is output from the steam-water separator 7. The controller 11 synchronously receives temperature and pressure signals to adjust the power of the variable frequency water pump 3 and the opening of the first safety valve 8 to maintain normal system operation.
[0042] The dynamic control strategy of controller 11 sets billet heating as the first priority: when the surface temperature of the billet is below 1150℃, controller 11 reduces the flow rate of variable frequency water pump 3 to 50% and prioritizes increasing the combustion power; when the seismic sensor detects that the acceleration of the kiln body is >0.3g, the kiln automatically stops and drains the water inside the high heat-resistant heat exchange tube.
[0043] The waste heat recovery device proposed in this invention has the following beneficial effects:
[0044] 1. By recovering waste heat in situ (heat exchange tubes are installed on the inner wall of flue 1 instead of the outlet), the comprehensive heat recovery rate of flue gas is improved, while the oxidation loss rate of steel billets and CO2 emissions are reduced. It has low requirements for equipment materials, reduces investment costs, and is suitable for industrial energy-saving renovation in multiple scenarios such as steel rolling, forging and heat treatment.
[0045] 2. This waste heat recovery device uses finned tubes (6), which can improve the heat exchange efficiency of the heat exchange tubes.
[0046] 3. This waste heat recovery device increases the comprehensive recovery rate of flue gas waste heat from 40% of traditional technology to over 85%, with a steam output of 6t / h (pressure 1.6MPa, temperature 250℃), while reducing energy consumption per ton of steel by 15% (natural gas consumption reduced by 1.5 million m³ / year).
[0047] 4. This waste heat recovery device has the advantages of simple structure and stable and reliable operation;
[0048] 5. By installing a safety valve, the risk of heat exchange tube rupture is reduced, and the lifespan of the heat exchange tube is increased.
[0049] This utility model also proposes a billet heating kiln that integrates high-temperature steam external supply function.
[0050] In this preferred embodiment, a billet heating kiln integrating high-temperature steam external supply function includes a kiln body with a flue 1 installed on the kiln body. A high-temperature resistant heat exchange tube 4 of the waste heat recovery device is installed on the inner wall of the flue 1. The specific structure and beneficial effects of the waste heat recovery device are the same as in the above embodiment and will not be repeated here.
[0051] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.
Claims
1. A waste heat recovery device of a billet heating furnace integrated with a high-temperature steam external supply function, characterized by, This includes high-temperature heat exchange tubes, a softened water supply system, a variable frequency water pump, a steam-water separator, and a first safety valve. Spiral fins are welded to the outer wall of the high-temperature heat exchange tube. The high-temperature heat exchange tube is installed on the inner wall of the flue of the kiln. The outlet of the softened water supply system is connected to the inlet of the high-temperature heat exchange tube through a variable frequency water pump. The outlet of the high-temperature heat exchange tube is connected to the external steam network through a steam-water separator and a first safety valve.
2. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, The fin height is 10~15mm, and the fin spacing along the length of the high-temperature heat exchange tube is 5mm~8mm.
3. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, The inlet of the high-temperature heat exchange tube is located at the high-temperature end of the flue, and the outlet of the high-temperature heat exchange tube is located at the low-temperature end of the flue.
4. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, It also includes a controller, which is electrically connected to the variable frequency water pump, water separator and first safety valve.
5. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 4, characterized in that, It also includes a temperature sensor installed inside the kiln and a pressure transmitter installed inside a high-temperature heat exchange tube. The controller is electrically connected to the temperature sensor and the pressure transmitter.
6. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, It also includes an acoustic soot cleaner installed on the outside of high-temperature heat exchange tubes to clean the dust accumulated on the fin surface.
7. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, It also includes a water quality detector installed between the softened water supply system and the variable frequency water pump.
8. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in claim 1, characterized in that, The high-temperature heat exchange tube includes multiple coils connected by flanges, and a second safety valve is installed at the end of each coil.
9. The waste heat recovery device for a billet heating kiln with integrated high-temperature steam external supply function as described in any one of claims 1 to 8, characterized in that, A V-shaped refractory bracket is provided below the high-temperature heat exchange tube to support it; the outer diameter of the high-temperature heat exchange tube is 150mm~200mm and the wall thickness is 8mm~12mm.
10. A billet heating kiln with integrated high-temperature steam external supply function, characterized in that, The device includes the waste heat recovery device as described in any one of claims 1 to 9, and also includes a kiln body on which a flue is provided.