CN106225014A - There is the round bottom of flue gas recirculation, flat vessel heater - Google Patents

Abstract

The invention discloses a round-bottomed and flat-bottomed vessel heating device with flue gas circulation, which includes a furnace and a burner. The heating device is arranged so that the burned flue gas generated by the burner can circulate inside the furnace, so that The ratio of the internal volume of the furnace to the bottom volume of a standard round-bottomed pan matching the furnace diameter is greater than 2.5, or the ratio between the internal volume of the furnace and the bottom volume of a standard pan matching the furnace diameter The ratio is greater than 2, and the ratio of the internal volume of the furnace to the bottom volume of a standard round-bottomed pot that is compatible with the diameter of the furnace is preferably greater than 4.5, or the internal volume of the furnace is compatible with the standard diameter of the furnace. The ratio of the bottom volume of the frying pan is preferably greater than 4; the present invention can greatly prolong the residence time of flue gas, and can strengthen the heating effect on round bottom or flat bottom vessel so as to obtain high thermal efficiency, simple structure, low cost, easy maintenance and New stove heating unit with long service life.

Description

Warmers for round and flat bottomed vessels with flue gas circulation

technical field

The invention relates to the technical field of stoves, in particular to a heating device for round-bottomed and flat-bottomed vessels with flue gas circulation.

Background technique

Commercial stoves mainly include Chinese cooking stoves, large pot stoves, soup stoves, etc. Traditionally, commercial stoves have had very low thermal efficiency. "Chinese Food Gas Cooking Stove" GB7824-1987 and CJ/T28-1999 require that the thermal efficiency is not less than 20%. "Chinese gas cooking stove" CJ/T 28-2003 cancels the performance requirements and test methods of thermal efficiency. The "Energy Efficiency Limits and Energy Efficiency Grades of Commercial Gas Stoves" GB30531-2014 implemented since January 2015 stipulates that the energy efficiency limit value of gas cooking stoves for Chinese food is 25%.

The reasons for the low thermal efficiency of commercial cookers are analyzed as follows: Fig. 1 and Fig. 2 are schematic structural diagrams of flue smoke exhaust type and indirect smoke exhaust type cooker respectively in the prior art. Referring to Fig. 1 , a burner 2 and a round-bottomed pot 3 are installed on the bottom and top of a funnel-shaped hearth 1 respectively, and the smoke exhaust port 4 provided on the wall of the furnace 1 leads the flue gas into the smoke exhaust pipe 5 . The residence time of the flue gas produced by the burner 2 in the furnace 1 is very short (for example, the rated heat load of the burner of a certain type of Chinese cooking stove is 42kW, the furnace diameter is 400mm, and the furnace depth is 270mm, and the residence time of the flue gas in the furnace is only is 0.17s). And because the chimney 5 has the effect of drawing wind, flame and smoke are easily deflected to the side of the smoke outlet 4, causing a lot of smoke to short-circuit and flow into the smoke outlet 4 without touching the bottom of the pan. Smoke emissions carry away most of the total heat release from fuel combustion. In addition, the furnace wall of the furnace 1 also has heat loss. Therefore, only about 20% can be transferred to the round-bottomed pot 3 in the total heat release of fuel combustion, and the remaining 80% is emitted to the surrounding environment in forms such as exhaust heat loss and furnace wall heat loss, and is wasted. In the indirect smoke-exhausting cooker shown in Figure 2, the round-bottomed pot 3 is supported by the pot bracket 6, and the smoke is discharged into the air in the kitchen through the annular gap between the round-bottomed pot 3 and the top of the furnace 1, and then the oil-absorbing fume The machine discharges to the outside. The residence time of the smoke in the furnace 1 is also very short, and the combustion smoke flows through the inner space of the kitchen, which is not conducive to improving the working conditions of the kitchen.

It is worth noting that the thermal efficiency data of the existing commercial stoves are obtained in the laboratory according to the prescribed test method, but there is a big difference between the laboratory test and the actual use conditions, for example: (1) the temperature of the cooker is different: the laboratory The test is to boil water and the temperature is lower than 100°C; when it is actually used for cooking, there is edible oil (its boiling point is higher than 260°C) in the round bottom pot, and the temperature of cooking is much higher than the temperature of boiling water. When the temperature of the pot is high, the heat transfer temperature difference between the flue gas and the pot is small, and the thermal efficiency is reduced. (2) The amount of smoke is different: Chinese cooking is used to stir-frying with high heat, and the amount of smoke is quite large. The larger the flue gas volume, the shorter the residence time and the lower the thermal efficiency. (3) Flame conditions are different: yellow flames often appear in actual use, and incomplete combustion is more serious. (4) The round bottom pot is often not covered when cooking, and the surrounding cold air entering the pot can cause additional convective heat loss. (5) Chinese cooking chefs are accustomed to throwing and frying, which sometimes causes the fire to burn empty and causes additional heat loss. Considering the above factors, the thermal efficiency of the Chinese cooking stoves in the prior art is generally lower than 20% under actual conditions of use.

The flue smoke exhaust type and indirect smoke exhaust type cooking stoves, large pot stoves, and soup stoves shown in Figure 1 and Figure 2 are widely used in various hotels, guesthouses, restaurants, restaurants, fast food restaurants, and collective canteens in the past and now. (Including the kitchen of various units such as factories, enterprises, institutions, institutions, schools, troops, social institutions, groups, etc.). According to the statistics of the catering industry, the total number of Chinese cooking stoves, large pot stoves and soup stoves in use in my country exceeds 100 million. It is generally believed that cooking fume is the third largest source of air pollution after automobile exhaust and industrial waste gas. Cooking fumes contain black carbon particles (PM2.5), nitrogen oxides, carbon monoxide, volatile organic compounds, and the greenhouse gas carbon dioxide. In addition, the stove heating device of the round bottom or flat bottom vessel similar to Fig. 1 and Fig. 2 is also widely used in many industries such as food industry, light industry, traditional Chinese medicine, and agricultural by-product processing. These stove heating devices with huge number, wide distribution and low thermal efficiency not only waste energy, but also pollute the environment. Therefore, the development of new and efficient stove heating devices has important practical significance for my country, a country with a large population, lack of energy resources, and facing huge environmental protection pressure.

Contents of the invention

The purpose of the present invention is to solve the problems of short residence time of flue gas and low thermal efficiency of the existing stove heating device, and provide a device that can greatly prolong the residence time of flue gas, and can strengthen the heating effect on round-bottomed or flat-bottomed vessels to obtain high thermal efficiency. A new stove heating device with simple structure, low cost, easy maintenance and long service life.

Technical scheme of the present invention is:

A round-bottomed and flat-bottomed vessel heating device with flue gas circulation includes a furnace and a burner, the heating device is arranged so that the combusted flue gas generated by the burner can circulate inside the furnace.

Further, the ratio of the internal volume of the furnace to the bottom volume of a standard round-bottomed pan suitable for the bore diameter is greater than 2.5, or the internal volume of the furnace is greater than 2.5, or The pot bottom volume ratio is greater than 2.

Preferably, the ratio of the internal volume of the furnace to the bottom volume of a standard round-bottomed pot that is compatible with the diameter of the furnace is preferably greater than 4.5, or, the internal volume of the furnace is compatible with the standard flat bottom of the furnace diameter The pot bottom volume ratio of the pot is preferably greater than 4.

Further, the hearth is in the shape of a drum, a waist drum, a gourd, a cylinder, a trumpet, an inverted funnel, a cuboid, a cube, or a polyhedron.

Furthermore, the burner is a blast burner, and the burner is installed at the center of the bottom of the furnace, and a smoke outlet is also opened on the furnace wall at the lower part of the furnace, or, the burner Installed on the furnace wall of the furnace, the furnace wall of the furnace is also provided with a smoke exhaust port, and the smoke exhaust port is located on the furnace wall on the same side as the burner.

Alternatively, the burner is an atmospheric burner, and the burner is installed at the center of the bottom of the furnace, and several secondary air inlets are provided on the bottom wall of the furnace around the burner. There is also a smoke exhaust port on the furnace wall.

Alternatively, the burner is composed of a solid fuel grate, the grate is installed at the center of the bottom of the furnace, the furnace wall of the furnace is provided with a furnace door, and the furnace wall of the furnace is also provided with a smoke vent.

Preferably, the blast-type burner is a blast-type gas burner, and the residence time of the burned flue gas generated by the blast-type gas burner in the furnace is greater than 1 second under rated heat load conditions.

Preferably, the heating device also includes a smoke exhaust tube, and the smoke exhaust port of the furnace communicates with the smoke exhaust tube; the heating device also includes a regulating valve, and the regulating valve is arranged between the smoke exhaust port and the The flue between the smoke exhaust tubes or is arranged on the smoke exhaust tubes.

Optionally, the heating device further includes an annular flue, the annular flue surrounds the furnace, and the furnace is uniformly provided with several smoke outlets along the circumference, and the several smoke outlets are connected to the annular A flue, the annular flue communicates with the exhaust pipe.

The novel heating device of the present invention is arranged so that the combusted flue gas produced by the burner can circulate inside the furnace, thereby prolonging the residence time of the combusted flue gas inside the furnace, and utilizing the advantages of these circulating combusted flue gases Convective heat transfer and radiation heat transfer to enhance the heating effect on round bottom or flat bottom vessels. Since the burned flue gas in the stove heating device of the present invention has a longer residence time inside the furnace, more heat of the burned flue gas is transferred to the round bottom or flat bottom vessel more fully, so compared with the prior art, the present invention The inventive stove heating device has better heating effect and higher thermal efficiency.

Description of drawings

Fig. 1 is a structural schematic diagram of a flue exhaust smoke cooker in the prior art.

Fig. 2 is a schematic structural view of an indirect smoke exhaust cooker in the prior art.

Fig. 3 is a schematic structural view of a stove heating device for a blast burner according to Embodiment 1 of the present invention.

Fig. 4 is a schematic structural view of a stove heating device for an atmospheric burner according to Embodiment 2 of the present invention.

Fig. 5 is a schematic structural view of a stove heating device burning solid fuel according to Embodiment 3 of the present invention.

detailed description

The present invention will be further described below in combination with specific embodiments. Wherein, the accompanying drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical drawings, and should not be construed as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings will be omitted, Enlargement or reduction does not represent the size of the actual product; for those skilled in the art, it is understandable that certain known structures and their descriptions in the drawings may be omitted.

The data enumerated in the present invention are only exemplary data given to better illustrate the embodiments of the present invention, and unless otherwise specified, do not constitute any limitation on the claims of the present invention.

Example 1

As shown in FIG. 3 , it is a schematic structural diagram of a stove heating device for a blast burner in the present invention. Referring to Fig. 3, a burner 2 and a round-bottomed pot 3 are respectively installed on the bottom and top of the drum-shaped hearth 1, and a smoke exhaust port 4 is provided on the furnace wall at the bottom side of the furnace 1 for passing flue gas into the smoke exhaust pipe 5. A regulating valve 7 is also provided on the flue between the smoke exhaust port 4 and the smoke exhaust tube 5 . In the device, the rated heat load of the burner is 20kW, the diameter of the furnace is 400mm, the depth of the furnace is 270mm, and the diameter of the furnace which is half the depth of the furnace is 600mm. The central axes of the furnace 1, the burner 2 and the round-bottomed pot 3 are coincident (hereinafter referred to as the central axis).

When the device is in operation, the burner 2 produces flames and high-temperature flue gas jets, and the flames and high-temperature flue gas jets of the blast burner have relatively large kinetic energy (the speed of the flame ejected from the burner fire hole is generally above 10m/s) ). Driven mainly by the kinetic energy of the flame and the jet of high-temperature flue gas, the combusted flue gas generated by the flame of the burner 2 flows upwards, and then flows upwards and outwards along the bottom of the round-bottomed pot 3 . These combusted flue gases flow downward when they are close to the wall of the furnace 1 , and then part of the combusted flue gas flows into the exhaust port 4 and is discharged outwards through the exhaust tube 5 . At the same time, when the valve 7 is adjusted to provide appropriate local flow resistance, part of the combusted smoke flows into the negative pressure zone at the root of the flame, and mixes with the flame jet to flow upward, and the combusted smoke that does not enter the negative pressure zone at the root of the flame flows It also flows upwards under the influence of jet flow transfer. The above process forms the circulation flow of the combusted flue gas inside the furnace 1 shown in FIG. 3 . The velocity distribution of the combusted flue gas circulating flow is an axisymmetric distribution centered on the central axis. The above-mentioned so-called "flame root negative pressure zone" refers to the flame root negative pressure zone that can drive the surrounding gas to flow upward when the flame is ejected from the burner 2 flame hole at a high speed, so that the gas density around the flame root becomes thinner. This negative pressure zone is capable of attracting surrounding burnt smoke into the flame jet. It can be seen from the above description that the driving force formed by the circulating flow of combusted flue gas shown in Figure 3 is the kinetic energy of the flame jet itself.

In this embodiment, the interior of the furnace 1 contains a large amount of high-temperature combusted flue gas, which can significantly enhance the heating effect of the round-bottomed pot 3, because:

(1) The contact between the burned flue gas and the bottom of the pot produces convective heat transfer, and the heat is transferred to the bottom of the pot.

(2) More importantly, the infrared radiation energy emitted by the burned flue gas inside the furnace 1 can transfer heat to the bottom of the pan. According to the theory of gas radiation heat transfer, the radiation intensity of flue gas is related to factors such as flue gas composition, flue gas temperature, flue gas volume and density.

(a) Flue gas composition: The carbon dioxide and water vapor contained in the flue gas have a strong ability to emit infrared radiation. Many types of fuel have a high hydrogen content, so that the combustion flue gas generally contains a high concentration of water vapor. For example, typical values for water vapor and carbon dioxide concentrations in natural gas combustion flue gas are 19% and 9.5% wet flue gas volume, respectively. In other words, nearly one-third of the gas components in natural gas flue gas can produce infrared radiation. In addition, the black carbon particles generated by the yellow flame also have a strong radiation ability (including visible light and infrared), so when the flame appears yellow flame, the radiation intensity of the smoke increases significantly.

(b) Flue gas temperature: When the temperature of the burned flue gas is higher than 1200°C, the infrared radiation emitted is quite strong; when the temperature is 900°C, the infrared radiation is still strong; when the temperature is lower than 600°C, the infrared radiation is relatively weak.

(c) Smoke volume and density: The characteristic of gas radiation is that all radiative gas molecules in the entire gas volume emit radiation at the same time, and what is received at the gas volume interface is the infrared radiation emitted by all radiative gas molecules in the entire gas volume. The superimposed sum of radiation. Therefore, the larger the gas volume and density, the higher the intensity of infrared radiation received at the volume interface. A parameter used to reflect the radiative capacity of a gas volume in gas radiative heat transfer is the average ray path. The larger the average ray path, the greater the radiative power. Smoke radiation is volume radiation. In FIG. 3 , the bottom of the round-bottomed pot 3 can receive the infrared radiant energy of the burned flue gas circulating in the furnace 1 (including the part directly received and the part reflected to the bottom of the pot by the wall of the furnace 1 ). The larger the internal volume of the furnace 1 or the higher the density of the flue gas it contains, the greater the infrared radiation energy received by the bottom of the pan.

Referring to Fig. 3, when a large amount of combusted flue gas circulates inside the furnace 1, as long as the temperature of the combusted flue gas is maintained above 800°C, the carbon dioxide contained in the combusted flue gas and the infrared radiant energy emitted by water vapor can The heat of the burned flue gas is transferred to the bottom of the pot above. If the burned flue gas contains black carbon particles generated by the yellow flame, the radiant energy of the black carbon particles in the circulating burned flue gas can also transfer heat to the bottom of the pot above. The burned flue gas circulating inside the furnace 1 is equivalent to an infrared heater. As long as the flame jet energy generated by the burner 2 is sufficient to maintain the internal temperature of the furnace 1 above 800°C, and can drive the combusted flue gas to produce a relatively significant circulation flow, so that the temperature distribution in the upper and lower parts of the furnace 1 is relatively uniform, then Fig. 3 The shown stove heating device can utilize the convective heat transfer and radiation heat transfer functions of the circulating burned flue gas to enhance the heating effect on the round-bottomed pot 3 .

In order to illustrate the beneficial effects of the present invention more clearly, the prior art Fig. 1 and Fig. 2 are compared and analyzed with Fig. 3 of the present embodiment below: in Fig. 1 and Fig. 2, the flue gas that burner 2 produces will inevitably Rapid upward discharge, this is the characteristic of high-temperature flue gas, therefore, the combusted flue gas that burner 2 flame produces is only one-time, and the pan bottom of round-bottomed pot 3 is briefly contacted in an instant (actually, in the burner 2 When the middle and high fire gears produce a large amount of smoke, in Figures 1 and 2, many smokes have been discharged upwards without touching the bottom of the pot). Due to the small heat exchange area of the bottom of the pot and the fast flow of flue gas, most of the heat of the flue gas is too late to be transferred to the bottom of the pot, and the heat is discharged to the atmosphere with the flue gas. Therefore, the thermal efficiency of the flue smoke exhaust type and indirect smoke exhaust type cooker in the prior art Fig. 1 and Fig. 2 is only about 20%.

In comparison, Fig. 3 of this embodiment is an artificial and purposeful arrangement of the stove heating device so that the burned smoke generated by the flame of the burner 2 cannot immediately drift upwards and leave the furnace 1, but can drive the burned smoke with the help of flame kinetic energy. The flue gas circulates inside the furnace 1 (it needs to cooperate with the local flow resistance generated by the specific shape of the furnace 1 and the regulating valve 7), so that the burned flue gas contacts the bottom of the pot multiple times and for a long time. convective heat transfer. More importantly, this embodiment can also use the infrared radiation energy of a large amount of circulating flue gas inside the furnace 1 to heat the bottom of the pan. Since the burned flue gas in this embodiment has a longer residence time inside the furnace 1, more heat from the burned flue gas is transferred to the bottom of the pot more fully, therefore, compared with the prior art, the stove heating device of this embodiment It has better heating effect and higher thermal efficiency.

For example, the rated heat load of the burner of a certain type of flue exhaust type blast cooking stove in the prior art is 42kW; the funnel-shaped furnace has a diameter of 400mm, a depth of 270mm, and a diameter of 120mm at the bottom of the furnace; the geometric volume of the furnace is ^0.0157m3 , the volume occupied by the bottom of the standard round-bottomed pan (depth 110mm) that is compatible with the furnace caliber (that is, the volume of the pot that is lower than the pot ring at the top of the furnace 1, hereinafter referred to as the volume of the bottom of the pot) is 0.0076m ³ (Note: Standard round-bottomed pans refer to round-bottomed pans with a diameter/depth ratio of 0.25 to 0.35; standard pans refer to "Energy Efficiency Limits and Energy Efficiency Grades for Household Gas Cookers" GB30720-2014, "Energy Efficiency Limits and Energy Efficiency Grades for Commercial Gas Cookers 》GB 30531-2014 test pots). The inner volume of the furnace is equal to the geometric volume minus the bottom volume of the pot: 0.0157–0.0076= ^{0.0081m 3} , the ratio of the inner volume of the furnace to the bottom volume of the pot is 0.0081/0.0076=1.07; The stroke is: 3.6x internal volume of the furnace/internal area of the furnace = 0.069m; the natural gas consumption of the rated heat load is 4.378m ³ /h, the flue gas volume at 900°C is 186.47m ³ /h, and the residence time of the flue gas inside the furnace is: Furnace internal volume/flue gas volume = 0.156s; 700°C flue gas volume is 154.67m ³ /h, and the residence time of flue gas inside the furnace is 0.19s. Since the residence time of the flue gas is only more than 0.1 second, it can be judged that the thermal efficiency of this type of blast cooking stove is low.

The rated heat load of the burner in this embodiment is 20kW, the diameter of the drum-shaped furnace is 400mm, the depth of the furnace is 270mm, and the diameter of the bottom of the furnace is 400mm; the geometric volume of the furnace is ^0.044m3 , and the bottom of the standard round-bottomed pot ( The volume occupied by a depth of 110mm) is 0.0076m ³ , the internal volume of the furnace is 0.0364 m ³ , and the ratio of the internal volume of the furnace to the bottom volume of the pot is 4.8. It can be seen that the internal volume of the drum-shaped furnace used in this embodiment is 0.0364/0.0081=4.5 times larger than the internal volume of the funnel-shaped furnace of a certain type of blast cooking range mentioned above under the same furnace diameter.

In this embodiment, the inner area of the furnace is 0.73m ² , and the average stroke of the rays radiated by the flue gas is: 3.6 x the inner volume of the furnace/the inner area of the furnace=0.1795m. The average ray path of flue gas radiation from the drum-shaped furnace used in this embodiment is 0.1795/0.069=2.6 times greater than that of the funnel-shaped furnace flue gas radiation of a certain type of blast cooking stove mentioned above.

The natural gas consumption of the rated heat load in this embodiment is 2.085m ³ /h, the flue gas volume at 900°C is 88.794m ³ /h, and the residence time of the flue gas inside the furnace is: inner volume of the furnace/flue gas volume=1.48s. The residence time of the flue gas in this embodiment is 1.48/0.156=9.5 times longer than the residence time of the flue gas of a certain type of blast cooking stove mentioned above.

The bottom area of the round bottom pot in this embodiment is 0.1636m ² , the flue gas temperature in contact with the bottom of the pot is about 1000°C, the temperature of the bottom of the pot is about 300°C, the heat transfer temperature difference is 700°C, and the convective heat transfer coefficient is about 25W /m ² ·°C (the circulating flow of combusted flue gas in Figure 3 is driven by flame kinetic energy, the flow velocity is not large, and the convective heat transfer coefficient of 25W/m ² ·°C is reasonable), then convective heat transfer = convective heat transfer Coefficient x pan bottom area x heat transfer temperature difference = 2.863kW.

In this embodiment, the average absolute temperature of the burned flue gas inside the drum-shaped furnace is 1173K, and when the average stroke of the flue gas radiation is 0.1795m, the blackness of the natural gas flue gas is 0.18 according to the Hottel line calculation diagram. Due to the slight yellow flame of the blast-type cooking stove, it is reasonable to estimate the blackness of the burned smoke to be 0.3. According to the fourth power law of radiation intensity, the radiation heat transfer of the burned flue gas = Stephen-Boltzmann constant x the blackness of the burned flue gas x the area of the bottom of the pot x the fourth power of the average absolute temperature of the burned flue gas = 5.273 kW.

The heating power to the bottom of the pan is: convective heat transfer+radiative heat transfer=2.863+5.273=8.136kW, thermal efficiency=heating power/burner rated heat load=40.7%. It can be seen that using the convective heat transfer and radiation heat transfer effects of the circulating burned flue gas can enhance the heating effect on the bottom of the pot and improve the thermal efficiency.

The heat transfer by radiation is greater than the heat transfer by convection. The influencing factors of convective heat transfer are convective heat transfer coefficient, pot bottom area and heat transfer temperature difference. The area of the pot bottom is determined by the size and shape of the pot, the heat transfer temperature difference depends on the flue gas temperature, and the convective heat transfer coefficient is mainly affected by the flue gas velocity. These three parameters cannot be greatly improved for stove heating devices. The radiation heat transfer is different, and the flue gas radiation is volume radiation. Under the condition that the area of the bottom of the pot remains unchanged, as long as the volume of flue gas under the bottom of the pot is increased, the superposition of the heat radiation emitted by the radiative gas and solid particles in these flue gas volumes can greatly increase the heat received by the bottom of the pot. Radiation intensity, thereby increasing the heat transfer of the burned flue gas to the bottom of the pot.

Combining the above data, the difference between the present invention and the prior art represented by a certain type of blast cooking stove is further explained: the rated heat load of a certain type of blast cooking stove is 42kW, and the residence time of flue gas in the furnace is only more than 0.1 second , its actual heating power for the bottom of the pot is about 8.4kW (which can meet the firepower demand of 400mm round bottom pot cooking 8kW). When the blower cooking stove is turned on to the medium fire gear (the heat load of the burner is reduced to 20kW), the residence time of the flue gas in the furnace is more than 0.3 seconds, and the flue gas is still one-time, within an instant, and the pot If the bottom is in contact with the bottom for a short time, the actual heating power of the bottom of the pot will be reduced to about 4.5kW when the fire is turned on, which cannot meet the firepower demand of a 400mm round bottom pot for cooking.

The rated heat load of the burner in this embodiment is 20kW. After adopting a drum-shaped furnace, a large amount of combusted flue gas circulates under the bottom of the pot, and contacts with the bottom of the pot multiple times for a long time. The residence time of the flue gas inside the furnace reaches 1.48 seconds. Through the convective heat transfer and radiation heat transfer of the circulating burned flue gas, the heating power of the bottom of the pot reaches 8.136kW under the rated heat load of the burner, which can meet the firepower demand of 400mm round bottom pot for cooking. In this embodiment, the heating power for the bottom of the pot is 8.136kW under the condition that the rated heat load of the burner is 20kW, so the thermal efficiency reaches 40.7%, which is doubled compared with the prior art.

In addition to stir-frying, round-bottomed pots are often used for cooking, steaming, frying, and stewing food. At this time, the burner in this embodiment can reduce the firepower to a heat load of 10kW. When the heat load decreases, the reduction of the flue gas volume will more than double the residence time of the flue gas inside the furnace 1 to 3s. The flue gas temperature in contact with the bottom of the pot is still high, but the flue gas flow rate is reduced, the convective heat transfer coefficient is about 15W/m ² ·℃, and the convective heat transfer is about 1.72kW. The average absolute temperature of the burned flue gas inside the furnace is reduced to 1073K, and the radiation heat transfer is about 3.69kW. The heating power to the bottom of the pot is about 5.41kW, and the thermal efficiency reaches 54.1%. It can be seen that when the heat load of the burner decreases, the residence time of the combusted flue gas increases and the thermal efficiency increases.

The formation of the combusted flue gas circulation in the stove heating device shown in Figure 3 of this embodiment and its energy-saving effect are related to the shape, volume and internal components of the furnace 1, the type and performance of the burner 2 (especially the amount of flue gas and flue gas Kinetic energy), the position and area of the smoke exhaust port 4, the induced wind force of the smoke exhaust tube 5, and the local flow resistance generated by the regulating valve 7, etc., are further explained as follows:

(1) The shape, volume and internal components of the furnace 1:

(a) Shape: The drum-shaped furnace is the best choice, which is not only conducive to the circulation of the burned flue gas, but also can increase the internal volume of the furnace, and is beneficial to the furnace wall to reflect the heat radiation of the flame and flue gas to the bottom of the pot, and When the internal volume of the furnace is the same, the heat dissipation area of the outer surface of the drum-shaped furnace is the smallest, and the materials required for making the furnace wall are also the least. Other hearth shapes such as waist drum shape, gourd shape, cylinder shape, trumpet shape, inverted funnel shape, cuboid, cube, polyhedron, etc. are also conducive to the formation of the circulation of burned flue gas. However, the funnel-shaped furnace commonly used in the prior art (Fig. 1 and Fig. 2) is not conducive to the formation of the circulation flow of the combusted flue gas.

(b) Volume: The larger the internal volume of the furnace 1, the greater the amount of flue gas that can be accommodated and circulated under the bottom of the pot, and the better the heating effect on the bottom of the pot. Therefore, the present invention should adopt larger internal volume of the furnace, and the ratio of the internal volume of the internal volume of the furnace to the standard round-bottomed pan that is suitable for the bore of the furnace should be greater than 2.5, or the internal volume of the furnace and the internal volume of the furnace should be greater than 2.5. The ratio of the volume of the bottom of a standard pan matching the above-mentioned furnace diameter should be greater than 2. Further, the ratio of the inner volume of the furnace to the bottom volume of a standard round-bottomed pot that is compatible with the diameter of the furnace is preferably greater than 4.5, or the inner volume of the furnace is adapted to the standard flat-bottomed pot with the diameter of the furnace. The pot bottom volume ratio of the pot is preferably greater than 4. If the ratio of the inner volume of the furnace to the volume of the bottom of the pot is only about 1, the amount of flue gas under the bottom of the pot is too small, and the effect of improving the thermal efficiency is not obvious even if the combusted flue gas circulates inside the furnace.

(c) Internal components: Arranging components such as shrouds, circular partitions, baffles, crimps or flue gas diverters inside the furnace 1 and placing venturi ejectors above the burner 2 can strengthen the burnt smoke. air circulation. However, commercial cooking stoves have a large heat load and a high furnace temperature, so installing components inside the furnace will greatly increase the cost, and the internal components of the furnace are easily damaged by overheating and difficult to maintain. Therefore, the present embodiment does not have furnace internals.

(2) Type and performance of burner 2 (especially flue gas volume and kinetic energy of flue gas):

The fuel used by the stove heating device shown in Fig. 3 of this embodiment can be gas (such as natural gas, liquefied petroleum gas, coal gas, etc.), fuel oil (such as diesel oil, heavy oil, alcohol-based fuel, etc.) or other (such as coal powder, coal water slurry Wait). The greater the kinetic energy of the flue gas generated by the burner 2, the stronger the circulation of the combusted flue gas. In this embodiment, those burners with high flame injection speed and high smoke kinetic energy should be selected. The depth of the drum furnace 1 in this embodiment should match the flame length of the burner 2 . For example, when a blast type fuel burner is used, since the fuel needs to be atomized and the flame jet has a relatively long length, the depth of the furnace 1 should be increased accordingly, which can increase the internal volume of the furnace 1, which is conducive to enhancing the heating of the bottom of the pot Effect. Some types of burners require supplemental secondary air in addition to the air supply shown in Figure 3. At this time, the secondary air injection port can be arranged around the burner 2 at the bottom of the furnace 1, which can enhance the circulation of the burned flue gas.

In actual use, the smoke volume and the kinetic energy of the smoke vary with the fire position of the burner 2 , and the ratio of the maximum smoke volume to the minimum smoke volume can reach 20 to 30 during cooking operations. When the burner 2 is in the high fire gear, the present embodiment can obtain a relatively strong circulation of the burned flue gas inside the furnace 1 . If the firepower of the burner 2 is small (such as heat preservation fire), the circular flow of the burned flue gas driven by the kinetic energy of the flue gas is not significant. When the firepower of the burner 2 is very small, the present embodiment can utilize the temperature difference inside the furnace 1 to generate the circulating flow of the combusted flue gas (that is, the fresh high-temperature flue gas produced by the burner 2 flame and the existing high-temperature flue gas in the furnace 1 The temperature difference of the old flue gas). Specifically, because the flue gas distribution inside the drum-shaped furnace 1 of this embodiment is always the flue gas with the highest temperature is located at the highest position in close contact with the bottom of the pan, and the flue gas with the lowest temperature is located at the lowest position close to the smoke exhaust port 4 Therefore, the fresh high-temperature flue gas produced by the burner 2 will flow upwards to reach the bottom of the pot and then contact the bottom of the pot fully and for a long time until most of its heat is transferred to the bottom of the pot and the temperature is lowered before gradually flowing down to reach the bottom of the pot. The smoke exhaust port 4 is exhausted behind, and the position under the pot will be occupied by the fresher high-temperature flue gas produced by the burner 2 at the same time. It can be seen that when the firepower of the burner 2 is very small (insulation fire), the high-temperature flue gas in the furnace 1 of this embodiment has a long heat exchange time to fully transfer heat to the bottom of the pot, so high thermal efficiency can be obtained.

However, in the indirect smoke exhaust cooker of the prior art Fig. 2 that is commonly used at present, no matter the amount of smoke is large or small, the smoke will float upwards quickly through the annular gap between the round bottom pot 3 and the top of the furnace 1, and the smoke Gas residence time is very short. In the flue-type cooker of the prior art shown in FIG. 1 , when the fire power of the burner 2 decreases, the residence time of the flue gas increases to a certain extent, but the difference is not significant. Only in the stove heating device with the arrangement shown in Fig. 3 of this embodiment, the hot flue gas produced by the burner 2 cannot drift upwards immediately, and the flue gas with a higher temperature inside the furnace 1 will flow upwards, and the flue gas with a lower temperature will flow upwards. The flue gas flows downward, so the high-temperature flue gas produced by burner 2 tends to stay under the pot, contact with the bottom of the pot for a long time, and fully transfer heat to the bottom of the pot, while the flue gas after lowering the temperature It tends to be discharged from the smoke exhaust port 4.

When the firepower of the burner 2 is small, the temperature of the lower part of the furnace 1 can be lower than the dew point temperature of the flue gas, and the water vapor contained in the flue gas will be condensed into condensed water, so that the latent heat of water vapor condensation of the burned flue gas can also be effectively utilized . It can be seen that this embodiment can also use the high-level heat value of fuel including the latent heat of condensation of flue gas water vapor. The low-level and high-level heat values of natural gas are 34.5 and 38.3 MJ/m ³ respectively. An additional 11% increase in thermal efficiency is obtained. Based on the above reasons, the present invention can achieve higher thermal efficiency when used in cooking operations with low heat for a long time (such as boiling, steaming, frying, stewing, stewing, boiling, stewing, stewing, etc.).

(3) The position and area of the exhaust port 4:

In this embodiment, the smoke outlet 4 is arranged at the bottom of the furnace 1 to facilitate the formation of the combusted smoke circulation flow. If the smoke exhaust port 4 is arranged on the upper part of the furnace 1, the smoke exhaust port 4 and the regulating valve 7 need to have a sufficiently large local flow resistance to form a circulating flow of the burned flue gas inside the furnace 1 . The area of the smoke exhaust port 4 should be designed according to the maximum smoke exhaust volume.

(4) The induced wind force of the chimney 5:

When using the blast type burner, even if the induced wind force of the chimney 5 is small, generally smoke can be smoothly exhausted. The smaller induced wind force is also beneficial to the formation of the combusted flue gas circulation inside the furnace 1 of this embodiment. If the draft force of the smoke exhaust tube 5 is too large, the burned flue gas in the furnace 1 may short-circuit and flow into the smoke exhaust port 4, which is not conducive to forming a strong circulation of the burned flue gas.

(5) Adjust the local flow resistance generated by the valve 7:

The main function of adjusting the valve 7 is to create the appropriate local flow resistance. The opening degree of the regulating valve 7 should be adjusted with the firepower of the burner 2 to achieve the required smoke exhaust volume. On the premise of achieving the required smoke exhaust volume, the opening of the regulating valve 7 should produce as large a local flow resistance as possible, which is conducive to the circulation of the burned flue gas inside the furnace 1 . For example, the induced wind force of the smoke exhaust tube 5 is 15Pa, and the opening of the valve 7 is adjusted to about 70% to produce a local flow resistance of 10Pa. The interior is a slight negative pressure of 1Pa. Under the above conditions, if there is no local flow resistance of 10Pa produced by adjusting the opening of the valve 7 to about 70%, the interior of the furnace 1 will reach a negative pressure of 11Pa. The residence time of the gas inside the furnace 1. It should be noted that appropriate local flow resistance can also be obtained by adopting other technical means without setting the regulating valve 7, or in other words, the regulating valve 7 can be replaced by other technical means (for example, selecting a suitable smoke outlet 4 or smoke channel flow area).

In this embodiment, in order to obtain a better effect of circulating the combusted flue gas inside the furnace 1, the regulating valve 7 should be properly adjusted according to the amount of flue gas. In order to simplify the actual operation, it is best to design the fire power adjustment mechanism of the burner 2 and the adjustment valve 7 as linkage (such as the fire power adjustment knob of the burner 2 and the rotation shaft of the adjustment valve 7 through mechanical transmission), and adjust according to cooking needs. The fire power gear of the burner 2 can automatically change the opening degree of the regulating valve 7 at the same time.

The implementation of the present invention is best to be able to fully understand the technical principles of the present invention, consider the comprehensive arrangement of the five aspects listed above, and properly adjust the operating conditions, which is more conducive to achieving a better effect of improving thermal efficiency. Merely making the furnace in the shape of a drum and providing smoke outlets at the bottom of the furnace cannot ensure significant circulation of the burned flue gas inside the furnace. The current design specifications for kitchen smoke exhaust facilities in large and medium-sized catering enterprises require that the chimney induced wind force should reach 10Pa or more. When the flue-type cooker is directly connected to the chimney with a draft force of 10Pa, but there is no measure to adjust the draft force, no matter what shape the furnace is, the burned flue gas inside the furnace will be sucked away by the draft force of the chimney, and it is difficult to form in the furnace. Significant combusted flue gas recirculation flows.

This embodiment also has other beneficial effects. For example, the circulating flow of combusted flue gas can return the incomplete combustion products or combustibles contained in the combusted flue gas to the flame combustion zone for burning, thus reducing the formation and emission of pollutants. The circulating flow of burned flue gas can also recirculate the remaining oxygen contained in the burned flue gas into the high-temperature combustion zone to participate in the oxidation reaction, so that the oxidant can be fully utilized, which can reduce the amount of air supplied to the burner 2 and reduce smoke exhaust The excess oxygen and nitrogen carry away the heat. The circulating flow of combusted flue gas can also reduce the temperature of the flame core area and reduce the formation of nitrogen oxides. In addition, the furnace wall of the furnace 1 in this embodiment is arranged away from the flame of the burner 2, which can reduce the heat resistance requirements of the furnace wall material, reduce the production and maintenance costs of the stove, and prolong the service life of the stove. This embodiment also has a good heat preservation effect: see Figure 3, after the cooking is finished and the burner 2 is turned off, as long as the regulating valve 7 is closed, the hot flue gas can stay inside the furnace 1, and the waste heat of the flue gas can continue to heat and heat the pot longer time. In comparison, in the prior art, after cooking in Figure 2, all the hot smoke flows upwards, which has no heat preservation effect; in Figure 1, after cooking, most of the hot smoke is discharged through the flue, which basically has no heat preservation effect.

The hearth 1 of the stove heating device shown in Fig. 3 is preferably made of cast steel or cast iron, and can also be made of refractory materials. There is an insulating layer on the outer wall of the furnace 1 (not shown in FIG. 3 ).

In this embodiment, burner 2 can also adopt other types of burners or heaters (such as infrared gas heaters) that do not need to utilize natural ventilation to supplement secondary air, and burner 2 can also be replaced by heaters (such as electric heating device, etc.). The type of fuel used by the burner 2 can be gas, oil or others.

Although this embodiment is described with a round-bottomed pan as an example, the stove heating device shown in FIG. 3 can also be used to heat other types of utensils.

Example 2

As shown in FIG. 4 , it is a schematic structural diagram of a stove heating device for an atmospheric burner of the present invention. Atmospheric burners are burners that use high-pressure gas to introduce primary air and rely on natural ventilation to supplement secondary air. The atmospheric burner does not need to be equipped with a blower, which avoids the power consumption and operating noise of the blower, and is often used as a burner for kitchen stoves.

Referring to Fig. 4, a burner 2 and a frying pan 8 are respectively installed on the bottom and top of the drum-shaped hearth 1 in this embodiment, and there are several secondary air inlets around the burner 2. A smoke outlet 4 is provided on one side of the furnace wall of the furnace 1 for passing the flue gas into the chimney 5 . The side wall of the drum-shaped furnace 1 is provided with a fire viewing window (not shown in FIG. 4 ).

Inside the furnace 1, the burner 2 produces a flame and a high-temperature flue gas jet, and the fuel-air mixture of the atmospheric burner is ejected from the burner fire hole at a speed of about 1 to 3m/s. Driven mainly by the kinetic energy of the flame and high-temperature flue gas jet, the combusted flue gas generated by the burner 2 flows upwards, then flows outwards along the bottom of the pan 8, and then flows upwards along the side wall of the pan. During the above flow process, the heat of the flue gas is transferred to the pot body, and the temperature of the flue gas decreases. The lower-temperature combusted flue gas then flows downward along the wall of the furnace 1 , and part of the combusted flue gas flows into the exhaust port 4 and is discharged outside through the exhaust tube 5 . At the same time, when the valve 7 is adjusted to provide appropriate local flow resistance, part of the combusted smoke flows into the negative pressure area at the root of the flame, and mixes with the flame jet and flows upward. The above process forms the circulation flow of the combusted flue gas inside the furnace 1 as shown in FIG. 4 .

Atmospheric burner 2 supplements secondary air by utilizing the induced wind force of chimney 5 . Changing the opening of the regulating valve 7 can adjust the amount of secondary air intake. The adjustment method is: when the burner 2 is on the high fire gear, the regulating valve 7 is fully opened, and the regulating valve 7 is half opened when the burner 2 is on the medium fire; fine-tuning is performed on the basis of the above. , is to slowly reduce the opening of the regulating valve 7, and observe the flame combustion of the burner 2 at the same time. As long as the flame burns stably, there is no yellow flame, and there is no falling smoke at the secondary air inlet, you can continue to reduce the opening of the regulating valve 7 to achieve the most suitable secondary air intake. If the flame of the burner 2 obviously deviates to the side of the exhaust port 4, the opening of the regulating valve 7 should also be appropriately reduced.

The bottom volume of the frying pan (that is, the volume of the pot that is lower than the pot ring on the top of the furnace 1 ) is relatively large. In this embodiment, the ratio of the inner volume of the furnace 1 to the volume of the bottom of the pot is about 3.

Although the present embodiment uses a frying pan as an example, the stove heating device shown in FIG. 4 can also be used to heat other types of utensils.

Parts not mentioned in this embodiment are similar to those in Embodiment 1, and will not be repeated here.

Example 3

As shown in FIG. 5 , it is a schematic structural diagram of a stove heating device burning solid fuel according to the present invention. Referring to FIG. 5 , a grate 9 is provided at the bottom of the drum-shaped furnace 1 , a smoke outlet 4 is provided on one side of the furnace wall of the furnace 1 , and a furnace door 10 is opened on the side of the furnace wall opposite to the smoke outlet 4 .

The operation process of the device is as follows: open the furnace door 10, put solid fuels into the furnace 1, and stack them on the grate 9 (these solid fuels can be coal or biomass fuels such as firewood, stalks, rice straw, wheat straw, organic waste, garbage Wait). Light the solid fuel piled up on the fire grate 9 with kindling, close fire door 10. The air originally present in the furnace 1 is used for the initial combustion of the solid fuel. Simultaneously, external air passes into solid fuel stack through grate 9 (can utilize forced ventilation such as blower or artificial bellows to blow into external air, or utilize natural ventilation). The flames and high-temperature flue gas produced by the combustion of these solid fuels flow upward to reach the bottom of the pot, then flow upward and outward, and then flow downward. Driven by the momentum transmission of the flame and high-temperature flue gas, it flows upwards, forming a circular flow of the combusted flue gas inside the furnace 1 .

The mechanism by which the bottom of the pan is heated includes convective heat transfer and radiation heat transfer. The components with strong heat radiation ability in the burned flue gas produced during the combustion of solid fuels include: (1) carbon dioxide; (2) water vapor (biomass fuel has a large moisture content, and its combustion flue gas generally has a high concentration of water vapor, sometimes as high as 30 to 50%); (3) black carbon particles generated by the yellow flame; (4) partially burned or burning solid fuel fragments, powder and coke particles entrained in the smoke; ( 5) Solid fuel ash and inorganic particles entrained in flue gas. At the combustion temperature, the above five components can all emit strong infrared radiation energy (the latter three components also produce visible light radiation), among which the thermal radiation of coke particles is the strongest, followed by black carbon particles. The blackness of solid fuel combustion flue gas generally reaches 0.5, and its heat radiation intensity is higher than that of the gas or oil flame flue gas of the above-mentioned embodiments 1 and 2. In this embodiment, the radiation heat transfer of the burned flue gas circulating inside the drum-shaped furnace 1 can greatly enhance the heating effect on the bottom of the pot and improve the thermal efficiency.

The grate 8 of this embodiment can adopt various grate forms of the prior art. The grate 8 has three functions: (1) supporting the solid fuel pile; (2) combustion-supporting air can pass into the furnace through the grate; (3) ash can be discharged through the grate. Depending on the purpose of the stove heating device of the present invention, simple fixed grates (generally arranged at even intervals by several iron rods with a diameter of about 5mm and a length of about 100mm are used for small or household use. When the solid fuel used is When coal is used, the interval between iron bars is about 5mm; when biomass fuel is used, the interval between iron bars is about 10mm). Ash bin, air duct etc. can also be installed below the grate 8, and these are known technologies. When the present invention is used as a commercial stove heating device with a large heat load, a mechanical grate can be selected as the grate 8 .

When natural ventilation is used to supply combustion-supporting air into the furnace, changing the opening of the regulating valve 7 can adjust the intake air intake of combustion-supporting air flowing through the grate 9, and the adjustment method is similar to that of embodiment 2 (the grate 9 and the The solid fuel pile is equivalent to the burner 2). When the solid fuel pile burns vigorously and the smoke volume is large, the regulating valve 7 is fully opened, and when the smoke volume is medium, the regulating valve is half-opened; Adjust the opening degree of valve 7 slightly, and observe the flame combustion situation at the same time. As long as the flame burns stably, there is no large-scale yellow flame, and no smoke falls from the grate 9, the opening of the regulating valve 7 can be continuously reduced to achieve the most suitable air supply.

In this embodiment, when forced ventilation is used to supply combustion-supporting air to the interior of the furnace 1 through the grate 8 , it is preferable to arrange the smoke outlet 4 at the bottom of the furnace 1 .

Biomass fuel contains high volatile matter and is mainly combusted in gas phase. In this embodiment, when biomass fuel is used and a blower is used to forcibly feed in the combustion-supporting air, a further improvement is to divide the combustion-supporting air into two paths: one path is primary air, which is passed through the grate 8; the other path is secondary air , sprayed into the interior of the furnace 1 through the furnace wall of the furnace 1. The secondary air injection method should be conducive to the formation of the combusted flue gas circulation shown in Figure 5 (for example, the secondary air injection inlet is arranged above the smoke exhaust port 4).

Parts not mentioned in this embodiment are similar to the above embodiments, and will not be repeated here.

In the above three embodiments, the smoke outlet 4 is all set on the furnace wall on one side of the furnace 1, which to a certain extent causes the asymmetric or uneven distribution of the circulating flow velocity of the burned flue gas inside the furnace 1 (although the adjustment of the valve 7 Local flow resistance can mitigate this asymmetry or non-uniformity). In order to avoid the above-mentioned shortcomings, the further improvement of the present invention is to set an annular flue, which surrounds the furnace 1, and on the furnace wall of the furnace 1, several smoke outlets are evenly opened along the circumference, and the several exhausts The smoke port communicates with the annular flue, and the annular flue communicates with the exhaust pipe 5 .

In the above three embodiments, the burner 2 is installed at the center of the bottom of the hearth, so that the heated pan can be heated evenly, but its disadvantage is that when the pan overflows, food is taken out from the pan, or food is taken from the stove heating device. When the cooker is put down, soup, oil droplets, vegetable chips, sundries, etc. are easy to fall into the burner 2 flame hole, which affects the performance of the burner and needs to be cleaned and maintained frequently. The burner needs to be replaced when the flame hole is seriously fouled, which is one of the reasons for the short service life of the commercial stove burner. In order to avoid the above-mentioned shortcomings, a further improvement of the present invention is to install the burner 2 on the furnace wall of the furnace 1 (the injection direction of the flame hole of the burner 2 is roughly the horizontal direction), and the smoke exhaust port 4 is opened on the same side as the burner 2. On the furnace wall on the side, preferably located below the burner 2 and close to the bottom of the furnace 1, a relatively strong circulation of the burned flue gas can also be formed.

The present invention does not relate to any complex, precise and expensive high-tech equipment components, nor does it involve advanced combustion technology. The invention seeks to solve practical problems aiming at the actual situation, and the proposed novel stove heating device has a simple structure and is practical. The essential technical feature of the present invention is that the stove heating device is arranged so that a large amount of combusted flue gas can circulate and flow under the bottom of the pan. When the present invention is implemented, it depends on many factors such as the type of fuel, the type and parameters of the burner, the shape, size and use of the vessel to be heated, direct or indirect smoke exhaust, and kitchen conditions. The furnace chamber of the novel furnace heating device of the present invention has a large furnace volume, and the furnace wall is far away from the flame, so the requirement on the heat resistance of the furnace wall material can be reduced. However, the heat dissipation area of the outer wall of the furnace increases accordingly, which requires higher heat insulation performance of the insulation layer. In addition, the regulating valve 7 also has certain heat resistance requirements. The regulating valve 7 can be installed in a position far away from the exhaust outlet 4, where the temperature of the flue gas is low, and where the valve adjustment is convenient (it can be arranged in the flue or the exhaust pipe).

Generally speaking, the invention has the advantages of high thermal efficiency, simple structure, low cost, easy maintenance and long service life.

In the above three embodiments, the adjustment is mainly based on the observation of the flame combustion situation, which is time-consuming, laborious and not precise enough. A further improvement of the present invention is to configure a PLC automatic control device, which is described as follows (taking the device shown in Figure 3 as an example using a blast-type gas burner): a carbon monoxide sensor and an oxygen sensor are installed in the flue, and the regulating valve 7 and the smoke outlet Pressure sensors are installed on the flue between 4, the blower of the burner 2 is installed with a frequency converter, the regulating valve 7 is a solenoid valve that is electronically controlled to change the opening, and a gas valve opening sensor is installed (the opening of the gas valve is determined by the user according to the cooking time). Firepower needs to be adjusted). The above sensors are connected to the PLC input terminal, and the PLC output terminal is connected to the frequency conversion speed regulator of the blower and the regulating valve 7 solenoid valves. The PLC control step is to quickly change the blower speed and adjust the opening of the valve 7 according to the gas valve opening signal, and then make fine adjustments on the basis of the above: if the carbon monoxide does not meet the standard, increase the blower speed; after the carbon monoxide reaches the standard, if the oxygen concentration is high, reduce the blower Rotational speed; adjust the opening of the valve 7 according to keeping the flue pressure between the regulating valve 7 and the exhaust port 4 as a negative pressure range of 1 to 4Pa for fine-tuning.

The above embodiments have provided specific implementations when the present invention is applied to common burners and commonly used round-bottomed pans and pans. These examples are only examples for clearly illustrating the present invention, rather than limiting the embodiment of the present invention. Due to the wide variety of burners used by people, and the variety of uses and forms of pots, there are many kitchen facilities of different types and sizes in different regions, and the installation and use conditions of the stove heating devices are quite different. Here it is impossible to give specific implementations of the present invention for each specific situation one by one, and it is not necessary and impossible to exhaustively list all the implementations of the present invention here.

For those skilled in the art, on the basis of the above-mentioned embodiments, other changes or changes in different forms can be made according to specific situations. For example, the buildings used by large catering companies generally have special chimneys with a height of 5 to 10 meters. In this case, the smoke outlets 4 of several sets of stove heating devices of the present invention can be connected to the same chimney. The opposite situation is that the buildings used by many small catering businesses (such as fast food restaurants, noodle shops) do not have special chimneys. In this case, the novel stove heating device of the present invention can be simplified. For example, in Fig. 4, the smoke exhaust pipe 5 can be canceled, and the smoke exhaust port 4 can be opened on the top of the furnace 1 (next to the pan 8), and the smoke exhaust port 4 is equipped with a regulating valve 7, and the flue gas of the stove heating device passes through the smoke exhaust port. Port 4 discharges directly into the kitchen air. Similar changes or modifications that can be made according to specific situations will be obvious to those of ordinary skill in the art.

Any modification, simplification, substitution, addition, combination, modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. there is the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: include burner hearth and burner, described in add Thermal is arranged as the burning fume of described burner generation and can circulate inside described burner hearth.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described The ratio of the bottom of a pan volume of the standard circular bottom pot that burner hearth internal capacity is suitable with described burner hearth bore be more than 2.5, or, described stove The ratio of the bottom of a pan volume of the standard flat bottom pot that thorax internal capacity is suitable with described burner hearth bore is more than 2.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described The ratio of the bottom of a pan volume of the standard circular bottom pot that burner hearth internal capacity is suitable with described burner hearth bore is preferably greater than 4.5, or, The ratio of the bottom of a pan volume of the standard flat bottom pot that described burner hearth internal capacity is suitable with described burner hearth bore is preferably greater than 4.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Burner hearth be drum type, waist drum shape, calabash shaped, cylindrical shape, horn-like, fall funnel-form, cuboid, square or polyhedron-shaped.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Burner is air blast burner, and described burner is arranged on described burner hearth bottom center, the stove of the bottom of described burner hearth Exhaust opening it is further opened with on wall, or, described burner is arranged on the furnace wall of burner hearth, and the furnace wall of described burner hearth is further opened with Exhaust opening, described exhaust opening be positioned at on the furnace wall of described burner homonymy.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Burner is atmospheric burner, and described burner is arranged on described burner hearth bottom center, the stove around described burner Offer several auxiliary air air inlets in thorax bottom wall, the furnace wall of described burner hearth is further opened with exhaust opening.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Burner is made up of the grate using solid fuel, and described grate is arranged on described burner hearth bottom center, described burner hearth Furnace wall is provided with fire door, and the furnace wall of described burner hearth is further opened with exhaust opening.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Air blast burner is blast type fuel gas burner, and described blast type fuel gas burner has produced under rated heat input, rated heat load operating mode Burning fume is more than 1s in the time of staying within described burner hearth.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Heater also includes smoke exhaust barrel, and the exhaust opening of described burner hearth connects described smoke exhaust barrel；Described heater also includes tune Joint valve, described control valve is arranged on the flue between described exhaust opening and described smoke exhaust barrel or is arranged on described smoke evacuation On cylinder.

The most according to claim 1 have the round bottom of flue gas recirculation, flat vessel heater, it is characterised in that: described Heater also includes that ring-shaped flue, described ring-shaped flue ring are had mercy on described burner hearth, and described burner hearth is offered some the most equably Individual exhaust opening, several exhaust openings described connect described ring-shaped flue, and described ring-shaped flue connects described smoke exhaust barrel.