CN209816205U - Flue gas circulating type steel plate medium-low temperature tempering furnace - Google Patents
Flue gas circulating type steel plate medium-low temperature tempering furnace Download PDFInfo
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- CN209816205U CN209816205U CN201920592491.1U CN201920592491U CN209816205U CN 209816205 U CN209816205 U CN 209816205U CN 201920592491 U CN201920592491 U CN 201920592491U CN 209816205 U CN209816205 U CN 209816205U
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Abstract
The utility model provides a flue gas circulating steel sheet medium and low temperature tempering furnace, this tempering furnace combines nozzle flame jet heating with circulating flue gas jet heating, because the flue gas temperature of supplying hot air nozzle is controllable, through using hot air nozzle to replace nozzle flame jet, the jet frequency can improve 4-5 times than using the nozzle, the burner gas stirs more acutely, avoids the steel sheet local overheating, realizes furnace temperature homogeneity; meanwhile, the flue gas with fixed temperature impacts the steel plate through high-frequency pulse jet flow of the hot air nozzle, so that the convection heat exchange efficiency is improved; the method and the device can realize high-precision uniform heating of the heat treatment furnace with large temperature span, strengthen low-temperature heat transfer efficiency, avoid the problem that the edge of the steel plate is overheated due to high flame temperature of the burner during low-temperature heating, promote the cyclic utilization of flue gas, reduce the emission of flue gas, save energy and reduce emission.
Description
Technical Field
The utility model relates to a medium plate heat treatment equipment and production technical field especially relate to the temperature range at 150 + 800 ℃ of a large temperature span's continuous type heat treatment furnace of low temperature heating.
Background
The high-strength heat-treated steel plate is mainly applied to the industries of engineering/cement machinery, heavy mining vehicles, military industry and the like, tempering treatment is needed, the treatment temperature is mostly 150-800 ℃, the performance has extremely high sensitivity to the temperature, certain varieties need temperature uniformity +/-5 ℃, and the conventional heat treatment furnace and the heating method are difficult to realize the uniformity requirement due to large temperature span, so a special high-precision medium-low temperature tempering furnace is needed.
At present, a tempering heat treatment furnace is widely used for heating by using open flame of a burner, when a steel plate is heated at a low temperature, heat transfer is mainly carried out in a convection mode, and the steel plate is generally directly heated by using a large number of low-power burners. The direct heating mode of the burners is adopted, the furnace temperature is flexibly adjusted, the response speed is high, the direct heating mode is suitable for the change of large heat supply load, and the direct heating mode is suitable for the change of high furnace temperature, but the combustion temperature of the burners at the edge part is high at low temperature, so that the overheating of the edge part of a plate is easily caused, and the wide-direction temperature is not uniform. Meanwhile, for the 150-plus 800 ℃ large-temperature span tempering furnace, the burner configuration cannot realize high pulse frequency enhanced convection in the full temperature range, and the heat transfer efficiency is low during low-temperature tempering.
In order to improve the temperature uniformity of the hearth and meet the requirement of a heat treatment process that the plate temperature uniformity is less than or equal to +/-5 ℃ during low-temperature tempering, some enterprises set stirring fans at the heat preservation section of the heat treatment furnace to strengthen means such as mixing and stirring of flue gas in the furnace and the like, and certain effects are achieved, but the effects are not obvious.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a low temperature tempering even heating device in steel sheet that nozzle flame efflux heating and circulation flue gas efflux heating combine to the problem that above-mentioned technique exists. The method and the device can realize high-precision uniform heating of the heat treatment furnace with large temperature span, strengthen low-temperature heat transfer efficiency and avoid the problem that the edge of the steel plate is overheated due to high flame temperature of the burner during low-temperature heating.
The above purpose is realized by the following scheme:
a low temperature tempering furnace in the circulating steel plate of the flue gas, soaking section and heat preservation section of the tempering furnace set up the circulating pulse jet system of the flue gas, the circulating pulse jet system of the flue gas includes circulating fan, upper hot-blast spray nozzle, lower hot-blast spray nozzle, concurrent heating temperature control device, diversion pipeline; wherein, the upper and the lower burners and the upper and the lower hot air nozzles are symmetrically arranged at the two sides of the hearth of the tempering furnace along the furnace rollers up and down, and the burners and the hot air nozzles are arranged in a staggered way; the circulating fan is arranged outside the furnace top, the inlet of the circulating fan is connected with the furnace chamber, and a protection valve is arranged, and the protection valve is closed at high temperature, so that the fan impeller is not influenced by high-temperature flue gas in the furnace; the outlet of the circulating fan is connected with a heat supplementing temperature control device through a flow guide pipeline, and the heat supplementing temperature control device is connected with a hot air nozzle through the flow guide pipeline;
the heat supplementing temperature control device consists of a heat supplementing burner, a cold air charging valve and a heat supplementing box; the middle of the heat supplementing box is provided with a hot air channel, two sides of the hot air channel are symmetrically provided with heat supplementing nozzles at the upper and lower parts close to the circulating flue gas inlet, a cold air blending regulating valve is arranged on a hole on a pipeline between the heat supplementing box and the circulating fan, and cold air is sent into a heat supplementing temperature control system; after the steel plate is heated by hot air sprayed from the hot air nozzle, the hot air is circulated by the circulating fan and is supplemented with heat again; the hot air temperature of the hot air nozzle is adjusted by a heat supplementing temperature control device, when the temperature is lower than a target value, the hot air is heated by a heat supplementing burner, and when the temperature is too high, the hot air is cooled and adjusted by a hot air blending valve.
An inlet thermocouple and a pressure transmitter are arranged on a flow guide pipeline between the outlet of the circulating fan and the heat supplementing temperature control device, and an outlet thermocouple is arranged on a flow guide pipeline connecting the heat supplementing temperature control device and the hot air nozzle;
the hot air nozzle jet smoke and the burner jet flame are both horizontal to the steel plate; each burner is provided with a set of burner controller, an air pulse valve and a fuel gas pulse valve; each hot air nozzle is provided with a pulse switch valve; the burners and the hot air nozzles in each 3-6 m range are divided into a control area, the burners in the control area are organized into a group, the hot air nozzles are organized into a group, the burners and the hot air nozzles in the group are respectively switched on and off according to the staggered sequence of the transmission side and the non-transmission side, and the high-temperature flue gas of the staggered jet flow forms a rotational flow field on the upper surface and the lower surface of the steel plate.
Further, the burner is a self-preheating burner or a sub-high-speed burner.
According to the low-temperature control method of the low-temperature tempering furnace in the flue gas circulation type steel plate, a heat source for heating the steel plate consists of the burners and the hot air nozzles, when the tempering furnace is heated, the on-off time of a single burner is changed along with the difference value between the set value and the actual value of the furnace temperature, and the pulse on-off time of the hot air nozzles adopts a short-time strategy to realize high-frequency pulse jet flow. The working modes of the burner and the hot air nozzle are divided into a high-temperature mode and a low-temperature mode, wherein in the high-temperature mode, the burner is heated by adopting pulsed jet flow, and the hot air nozzle is closed; in the low-temperature mode, a hot air nozzle is adopted for pulse jet, the burner is closed, the flue gas sprayed by the hot air nozzle is sucked out of the tempering furnace by a strong circulating fan, is sent into a heat supplementing and temperature adjusting device after being pressurized to adjust to the target temperature, and then is sent into the hot air nozzle through a flow guide pipeline; the revolution of the circulating fan and the pressure transmitter form pressure closed loop constant pressure control, and a PID control strategy is adopted; a heat supplementing burner, a cold charging valve and an outlet thermocouple of the heat supplementing and temperature adjusting device form temperature closed-loop control and are respectively controlled by two PID control loops; and calibrating a relation curve between the temperature at the outlet thermocouple and the thermocouple at the heat preservation section in the furnace, wherein the target set value of the temperature closed loop is obtained based on the interpolation of the calibration curve.
Further, the high-temperature mode and low-temperature mode limit temperatures are 300-500 ℃.
Further, the air pressure of the outlet of the circulating fan is controlled within 1-5kPa at constant pressure.
Compared with the prior art, the beneficial effects of the utility model are that:
because the temperature of the flue gas supplied to the hot air nozzle is controllable, the hot air nozzle is used for replacing flame jet of the burner, the jet flow frequency can be improved by 4-5 times compared with that of the burner, the stirring of furnace gas is more violent, the local overheating of a steel plate is avoided, and the uniformity of the furnace temperature is realized; meanwhile, the flue gas with fixed temperature impacts the steel plate through high-frequency pulse jet flow of the hot air nozzle, and the convection heat exchange efficiency is improved.
The utility model discloses adopt protection valve to close when the centrifugal fan of device design is high temperature, can reduce the fan high temperature resistance performance requirement, reduce the tempering furnace investment. Compared with the prior art, the centrifugal fan circulates the flue gas in the furnace when in work, so that the flue gas emission can be reduced, and the energy conservation and emission reduction are realized.
The utility model discloses the device has that low temperature heating homogeneity is good, flue gas cyclic utilization, reduces smoke emission's performance. The utility model discloses the technique for when furnace temperature 150 ℃ -800 ℃ roller hearth tempering furnace realizes that the steel sheet is heated at 150 ℃ -400 ℃, its temperature uniformity is within 5 ℃.
Drawings
FIG. 1 is a diagram of a flue gas circulation pulse jet system.
FIG. 2 is a structural view of the heat compensating device.
FIG. 3 is a schematic view of a high-temperature self-protection structure of the centrifugal fan.
Fig. 4 hot air nozzle layout.
Fig. 5 shows the heating characteristics of the steel sheet.
In the figure: 1, a heat supplementing temperature control device; 2, circulating a fan; 3, tempering a hearth of the furnace; 4 flow regulating valve; 5, a pulse valve; 6 hot air nozzles; 7, a water outlet; 8, a water inlet; 9 protecting the valve; 10 heat supplementing burner 1 #; 11 heat compensating burner 2 #; 12 a circulating flue gas inlet; 13 circulating flue gas outlet.
Detailed Description
Example (b): taking a heat treatment furnace with the temperature range of 150-.
The utility model provides a low temperature tempering furnace in circulating steel sheet of flue gas, back stove district sets up 1 set of flue gas circulation pulse fluidic system in the tempering furnace.
As shown in fig. 1, the flue gas circulating pulse jet system comprises a circulating fan 2, an upper hot air nozzle, a lower hot air nozzle, a heat supplementing temperature control device 1 and a flow guide pipeline; wherein, the upper and the lower burners and the upper and the lower hot air nozzles are symmetrically arranged at the two sides of the hearth of the tempering furnace along the furnace rollers up and down, and the burners and the hot air nozzles are arranged in a staggered way; the circulating fan is arranged outside the furnace top, the inlet of the circulating fan is connected with the hearth, and a protective valve 9 is arranged; the outlet of the circulating fan is connected with the heat supplementing temperature control device 1 through a flow guide pipeline, and the heat supplementing temperature control device 1 is connected with a hot air nozzle through the flow guide pipeline;
the heat supplementing temperature control device 1 consists of a heat supplementing burner, a cold air charging valve and a heat supplementing box; the middle of the heat supplementing box is a hot air channel, two sides of the hot air channel are symmetrically provided with heat supplementing nozzles up and down near the circulating flue gas inlet 12, a cold air blending regulating valve is arranged on an opening of a pipeline between the heat supplementing box and the circulating fan, and cold air is sent into a heat supplementing temperature control system;
an inlet thermocouple and a pressure transmitter are arranged on a flow guide pipeline between the outlet of the circulating fan and the heat-supplementing temperature control device 1, and an outlet thermocouple is arranged on a flow guide pipeline connecting the heat-supplementing temperature control device 1 and the hot air nozzle;
the hot air nozzle jet smoke and the burner jet flame are both horizontal to the steel plate; each burner is provided with a set of burner controller, an air pulse valve and a fuel gas pulse valve; each hot air nozzle is provided with a pulse switch valve; dividing burners and hot air nozzles in each 3-6 m range into a control area, weaving burners into a group in the control area, weaving hot air nozzles into a group, respectively switching the burners and the hot air nozzles in the group according to the staggered sequence of a transmission side and a non-transmission side, and forming a swirling flow field on the upper surface and the lower surface of the steel plate by the high-temperature flue gas of staggered jet flow; the on-off time of a single burner varies with the difference value between the set value and the actual value of the furnace temperature, and the pulse on-off time of the hot air nozzle adopts a short-time strategy to realize high-frequency pulse jet.
The centrifugal fan 1 can generate strong convection circulation, and the hot air pressure is 1-5kPa, so that the hot air nozzle has certain jet velocity. In order to protect the impeller of the fan 1, the fan of the circulating system is arranged outside the furnace top, a protection valve is arranged at the circulating inlet of the fan, and the protection valve is closed at high temperature, so that the fan impeller is not influenced by high-temperature smoke in the furnace. The diversion pipeline connected with the outlet of the fan is in a circular pipe shape, the pipeline is provided with a pressure transmitter, and the outlet wind pressure is controlled within 1-5kPa at a constant pressure.
When the heat treatment furnace is heated, the burner group is adopted to heat at the temperature of above 400 ℃ and the hot air nozzle group is closed, and the hot air nozzle group is adopted to heat at the temperature of below 400 ℃ and the burner group is closed. The revolution of the circulating fan and the pressure transmitter form pressure closed loop constant pressure control, and a PID control strategy is adopted. The heat supplementing burner, the cold air charging valve and the outlet thermocouple form closed-loop temperature control and are respectively controlled by two PID control loops. And calibrating a relation curve between the temperature of the thermocouple and the thermocouple at the heat preservation section in the furnace, wherein the target set value of the temperature closed loop is obtained based on the interpolation of the calibration curve.
During production, the steel plate is placed on the furnace roller, and is sent into the heat treatment furnace and is sent out of the heat treatment furnace according to the process set program. Example the circulation system was tested to obtain steel plate heating characteristics as shown in figure 5 when operating with the process parameters shown in table 1, with the uniformity of the steel plate within ± 5 ℃ after entering the hold section.
| Hot air pressure kPa | Temperature of hot air | Temperature in the furnace | Frequency of pulses |
| 2.0 | 335℃ | 315℃ | 15-30s |
The heating curve of the 45mm steel plate is shown in FIG. 5, and the temperature uniformity of the measured steel plate at the heat preservation stage is within + -5 ℃.
The above description is only for the preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A flue gas circulating type steel plate medium-low temperature tempering furnace is characterized in that a tempering section and a heat preservation section of the tempering furnace are provided with a flue gas circulating pulse jet system, and the flue gas circulating pulse jet system comprises a circulating fan (2), an upper burner, a lower burner, an upper hot air nozzle, a lower hot air nozzle, a heat supplementing temperature control device (1) and a flow guide pipeline; wherein, the upper and the lower burners and the upper and the lower hot air nozzles are symmetrically arranged at the two sides of the hearth of the tempering furnace along the furnace rollers up and down, and the burners and the hot air nozzles are arranged in a staggered way; the circulating fan is arranged outside the furnace top, the inlet of the circulating fan is connected with the furnace chamber, and a protection valve (9) is arranged, and the protection valve is closed at high temperature, so that the fan impeller is not influenced by high-temperature flue gas in the furnace; the outlet of the circulating fan is connected with the heat supplementing temperature control device (1) through a flow guide pipeline, and the heat supplementing temperature control device (1) is connected with the hot air nozzle through the flow guide pipeline;
the heat-supplementing temperature control device (1) consists of a heat-supplementing burner, a cold-charging air valve and a heat-supplementing box; the middle of the heat supplementing box is provided with a hot air channel, the two sides of the hot air channel are symmetrically provided with heat supplementing nozzles at the upper and lower parts close to the circulating flue gas inlet (12), a cold air blending regulating valve is arranged on an opening of a pipeline between the heat supplementing box and the circulating fan, and cold air is sent into a heat supplementing temperature control system; after the steel plate is heated by hot air sprayed from the hot air nozzle, the hot air is circulated by the circulating fan and is supplemented with heat again; the hot air temperature of the hot air nozzle is adjusted by a heat supplementing temperature control device, when the temperature is lower than a target value, the hot air is heated by a heat supplementing burner, and when the temperature is too high, the hot air is cooled and adjusted by a cold air blending valve;
an inlet thermocouple and a pressure transmitter are arranged on a flow guide pipeline between the outlet of the circulating fan and the heat-supplementing temperature control device (1), and an outlet thermocouple is arranged on a flow guide pipeline connecting the heat-supplementing temperature control device (1) and the hot air nozzle;
the hot air nozzle jet smoke and the burner jet flame are both horizontal to the steel plate; each burner is provided with a set of burner controller, an air pulse valve and a fuel gas pulse valve; each hot air nozzle is provided with a pulse switch valve; the burners and the hot air nozzles in each 3-6 m range are divided into a control area, the burners in the control area are organized into a group, the hot air nozzles are organized into a group, the burners and the hot air nozzles in the group are respectively switched on and off according to the staggered sequence of the transmission side and the non-transmission side, and the high-temperature flue gas of the staggered jet flow forms a rotational flow field on the upper surface and the lower surface of the steel plate.
2. The medium-low temperature tempering furnace of a flue gas circulating type steel plate as claimed in claim 1, wherein said burner is a self-preheating burner or a sub-high velocity burner.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920592491.1U CN209816205U (en) | 2019-04-28 | 2019-04-28 | Flue gas circulating type steel plate medium-low temperature tempering furnace |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920592491.1U CN209816205U (en) | 2019-04-28 | 2019-04-28 | Flue gas circulating type steel plate medium-low temperature tempering furnace |
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| CN209816205U true CN209816205U (en) | 2019-12-20 |
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| CN201920592491.1U Withdrawn - After Issue CN209816205U (en) | 2019-04-28 | 2019-04-28 | Flue gas circulating type steel plate medium-low temperature tempering furnace |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109929970A (en) * | 2019-04-28 | 2019-06-25 | 东北大学 | Low-temp temper furnace and low temperature control method in a kind of smoke gas circulating type steel plate |
-
2019
- 2019-04-28 CN CN201920592491.1U patent/CN209816205U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109929970A (en) * | 2019-04-28 | 2019-06-25 | 东北大学 | Low-temp temper furnace and low temperature control method in a kind of smoke gas circulating type steel plate |
| CN109929970B (en) * | 2019-04-28 | 2023-09-22 | 东北大学 | Flue gas circulating type steel plate medium-low temperature tempering furnace and low temperature control method |
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| AV01 | Patent right actively abandoned | ||
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| AV01 | Patent right actively abandoned |
Granted publication date: 20191220 Effective date of abandoning: 20230922 |
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| AV01 | Patent right actively abandoned |
Granted publication date: 20191220 Effective date of abandoning: 20230922 |