Diffuse regenerative combustion industrial furnace and heating method

Abstract

Disclosed in the present invention is a diffuse regenerative combustion industrial furnace, comprising a furnace chamber, an airflow reversing system and at least two regenerative boxes, wherein burners are mounted on the furnace chamber, at least two burners are provided, and within a period of time in a low-temperature stage, the at least two burners maintain continuous operation without interruption, the low-temperature stage referring to a period of time in which the temperature in the furnace chamber has not reached the auto-ignition temperature of fuel. Further provided in the present invention is a heating method for heating a material by using the diffuse regenerative combustion industrial furnace described above. The diffuse regenerative combustion industrial furnace of the present invention completely eliminates the risk of deflagration in a diffuse regenerative combustion system, resulting in significantly higher safety and significantly improved production efficiency, and successfully solving the problem in the prior art of low production rate.

Description

Diffusion regenerative combustion industrial furnace and heating method TECHNICAL FIELD

[0001] The present application belongs to the field of combustion equipment, and particularly relates to a combustion industrial furnace and a heating method. BACKGROUND

[0002] Premix combustion is a traditional combustion method with a long history. Premix combustion adopts a method of mixing fuel and combustion-supporting air in a combustion chamber to organize a combustion process. After combustion, flue gas containing tail flame is sprayed into a furnace to heat materials in the furnace.

[0003] Diffusion combustion does not set a combustion chamber, but adopts a method of injecting fuel and combustion-supporting air into a furnace separately at a jet velocity of combustion-supporting air higher than that of fuel, so that the rapid combustion-supporting air flow entrains fuel and combustion products in the furnace, dilutes the oxygen volume concentration of the reaction zone, and obtains a local low-oxygen atmosphere. The fuel gradually combines with oxygen to burn in this high-temperature low-oxygen atmosphere, and recombination processes such as cracking are accompanied, resulting in completely different thermodynamic conditions from premix combustion and diffusion combustion with only fuel jet. The heat energy is released under delayed combustion with lean oxygen gas.

[0004] Combination of premix combustion and regenerative combustion is a traditional premix regenerative combustion system. Combination of diffusion combustion and regenerative combustion is a diffusion regenerative combustion system. In terms of energy efficiency, both combustion systems have obvious energy-saving effect due to the use of regenerative waste heat recovery and utilization. In terms of environmental protection, the diffusion regenerative combustion system has significantly better environmental protection performance than the premix regenerative combustion system because the diffusion regenerative combustion system forms a combustion flame with a large volume and a significantly reduced high-temperature zone temperature, so that the amount of thermal NOx is greatly reduced. NOx is one of the main culprits of air pollution, so the diffusion regenerative combustion system has significantly better environmental protection performance than the premix regenerative combustion system. x x

[0005] ​​In the field of industrial combustion technology, in recent years, the diffusion type regenerative combustion technology has begun to be popularized and applied, which brings the use effect of both energy saving and environmental protection. The system has the same working steps as the premixing type regenerative combustion system, and two ignition guns keep the eternal fire to ensure the safety of the combustion system. When one main air channel inputs secondary combustion air, the corresponding burner inputs fuel and is in working state, and the other main air channel is in exhaust state, and the corresponding burner stops working. However, the difference between the diffusion type regenerative combustion system and the premixing type regenerative combustion system is that the premixing type regenerative combustion system is provided with a special combustion chamber, as shown in FIG. 1. The diffusion type regenerative combustion system does not have a special combustion chamber, but uses the material-filled hearth as the main combustion site. Therefore, when the hearth is filled with materials, the diffusion type regenerative combustion system has limited space for fuel mixing and combustion in the hearth. The fuel sprayed by the burner working in cooperation with the main air channel enters the gap in the low-temperature material without being burned, and the unburned fuel accumulates and mixes with the air in the gap to form explosive gas. When the amount of accumulated unburned fuel is large, during the reversing process of the reversing system, the original burner is extinguished, and after an interval of 1-2 seconds, the other burner starts to work, and the flame sprayed by the burner ignites the unburned explosive gas accumulated in the low-temperature material to cause an explosion. The premixing type regenerative combustion system does not have the above explosion problem because it is provided with a combustion chamber and there is no accumulation of unburned residual fuel in the hearth.

[0006] Taking the diffusion type regenerative combustion system with double regenerative boxes as an example, in order to avoid the above explosion phenomenon, the following two measures must be taken: one is to reduce the fuel supply amount of the burner to reduce the total amount of fuel accumulation, and usually the initial stage of the low-temperature stage has only 15-30% of the maximum power of the burner, which will greatly prolong the time of the low-temperature stage to the high-temperature stage, and reduce the production efficiency of the system. The second is to prolong the time interval from the stop of the last burner to the start of the next burner in the switching process of the burner, that is, to prolong the interval time, so that the accumulated explosive gas has enough time to discharge from the hearth. Usually, the interval time will be increased by 3-6 times to barely ensure safety, for example, the interval time is increased from 1-2 seconds to 6-12 seconds. If the regenerative system reversing period is 60 seconds, the interval time is 10%-20% of a running period, and the burner does not work during the interval time. Prolonging the interval time further reduces the production efficiency of the system and increases the energy consumption of the system, and the explosion hazard is still not completely eliminated, but the frequency and energy size of the potential explosion are reduced to an acceptable level.

[0007] Therefore, the use of the diffusion type regenerative combustion system is limited due to the above safety and efficiency problems, and the energy saving and environmental protection advantages of the diffusion type regenerative combustion system cannot be fully utilized.

[0008] Only by solving the safety and production efficiency problems of the dispersion type heat accumulating combustion system, it is possible to completely replace the premix type heat accumulating combustion system technology with the dispersion type heat accumulating combustion system which is energy-saving and environment-friendly, and lay a foundation for the industry to enter a completely new dispersion type heat accumulating combustion system era which is energy-saving, environment-friendly and high-efficiency. SUMMARY

[0009] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the above background art, and to provide a dispersion type heat accumulating combustion industrial furnace which can solve the anti-explosion phenomenon, has high safety and high production efficiency, and a heating method for heating materials by using the dispersion type heat accumulating combustion industrial furnace.

[0010] To solve the above technical problems, the technical solution provided by the present application is as follows:

[0011] A dispersion type heat accumulating combustion industrial furnace, comprising a furnace chamber, an air flow reversing system and at least two heat accumulating boxes, wherein a burner is installed on the furnace chamber, and the burner is provided with at least two burners, and at least two burners keep continuous and uninterrupted work in a time period of a low temperature stage (in a certain time period or in the whole time period), and the low temperature stage refers to a time period when the temperature in the furnace chamber (including the low temperature area) does not reach the fuel self-ignition temperature.

[0012] In the above dispersion type heat accumulating combustion industrial furnace, preferably, the low temperature stage comprises the following time period: the starting point is to start heating the furnace chamber by turning on the burner, and the end point is after the burner works for 10-60 minutes, and at least two burners keep continuous and uninterrupted work in the time period from the starting point to the end point. The starting point of the above time period is the time point of starting the furnace and igniting, and the end point is the time point after the burner works for 10-60 minutes, for example, the end point is after the burner works for 10 minutes, or after the burner works for 20 minutes, or after the burner works for 30 minutes, or after the burner works for 40 minutes, or after the burner works for 50 minutes, or after the burner works for 60 minutes. In the above time period, the temperature in the furnace chamber may not reach the fuel self-ignition temperature, at this time, two burners keep continuous and uninterrupted work at the same time, and do not reverse with the system, which can solve the anti-explosion phenomenon and improve the production efficiency. For special cases, such as slow heating speed in the furnace chamber, the above end point can be extended, for example, after the burner works for 70 minutes, or after the burner works for 80 minutes, or after the burner works for 90 minutes, or after the burner works for 100 minutes, or after the burner works for 110 minutes, or after the burner works for 120 minutes, which is the end point of the above time period.

[0013] In a period after the start of the operation of the burners, the temperature in the area of the furnace far from the burners is lower, which can be a low-temperature area, and the temperature in the area of the furnace close to the burners is higher, which can be a high-temperature area. The temperature in the furnace reaching the fuel self-ignition temperature means that the temperature at any point in the furnace (including the high-temperature area and the low-temperature area) reaches the fuel self-ignition temperature. For example, the temperature near the outlet of the burners can have reached the fuel self-ignition temperature, but the temperature at other positions far from the outlet of the burners can not have reached the fuel self-ignition temperature, which can be referred to as a low-temperature stage.

[0014] In a more preferred solution, the working mode of 2 regenerators + 2 burners is adopted, or the working mode of 2 regenerators + 3 burners is adopted, and all the burners are kept in continuous and uninterrupted operation in the whole time period of the low-temperature stage.

[0015] In the above-mentioned diffuse regenerative industrial furnace, preferably, the secondary combustion air heated by the regenerators enters the furnace through the main air channel, the inlet of the burners is connected with the fuel inlet, the outlet of the burners is used for spraying flames and fuel into the furnace, and the regenerators are arranged close to the burners to ensure that the secondary combustion air provided by the regenerators can be supplied to all the burners in operation to promote the full combustion of the fuel sprayed by the burners. The arrangement of the regenerators close to the burners can make the distance between the two regenerators far, and the distance between any regenerator and any burner is less than the distance between the two regenerators, so that the gas flow between the two regenerators can pass through the burners in operation as much as possible (the distance between the two regenerators is far, the gas flow between the regenerator inputting the secondary combustion air and the regenerator discharging the exhaust gas forms a flow field, and the arrangement position of the burners makes the fuel sprayed by all the burners in operation in the flow field), so that the secondary combustion air sprayed by the regenerators can be supplied to all the burners in operation.

[0016] In a more preferred solution, when the regenerators and the burners are located on the same side of the furnace, the burners are located between the regenerators.

[0017] In a more preferred solution, when the two regenerators and the two burners are located on different sides of the furnace, the connecting lines of the two regenerators and the two burners form a quadrilateral, and the two regenerators are located on a pair of opposite corners of the quadrilateral, and the two burners are located on another pair of opposite corners of the quadrilateral.

[0018] In the above-mentioned industrial furnace with diffuse regenerative combustion, preferably, in the low-temperature stage, the actual power of the burners that are continuously and uninterruptedly working in at least one first time period is not more than 40% of the system reference average power, the actual power of the burners being the ratio of the amount of fuel sprayed by the burners to the time used for spraying the fuel, and the system reference average power being the ratio of the total amount of fuel consumed by each product of the furnace to the working time (the longest time required to meet the speed requirement) during which the total amount of fuel is consumed.

[0019] In the above-mentioned industrial furnace with diffuse regenerative combustion, preferably, the starting point of the first time period is the starting point of the low-temperature stage, and the ending time is determined according to the heating condition of the system.

[0020] In the above-mentioned industrial furnace with diffuse regenerative combustion, preferably, in the low-temperature stage, the oxygen volume in the total primary air provided in the auxiliary air inlets of the burners that are continuously and uninterruptedly working in at least one second time period is v1, the volume of the theoretical oxygen required for the combustion of all the fuel sprayed by all the burners is v2, and v1 / v2 is not less than 35%.

[0021] In the above-mentioned industrial furnace with diffuse regenerative combustion, preferably, the starting point of the second time period is the starting point of the low-temperature stage, and the ending time is determined according to the heating condition of the system.

[0022] In the present application, the first time period and the second time period can be the same time period, such as the time period from the start of heating the hearth by the burners to the end of the working of the burners for 10-60 min. Of course, the first time period and the second time period can also be different time periods, such as the first time period being earlier or later than the second time period, and the specific condition can be determined according to the actual condition.

[0023] As a general technical concept, the present application also provides a heating method for heating materials by using the above-mentioned industrial furnace with diffuse regenerative combustion, which comprises the following steps:

[0024] The materials are loaded into the hearth, and the burners are used to spray flames and fuel into the hearth for heating the loaded materials. In a time period in the low-temperature stage, all the burners are continuously and uninterruptedly working without being affected by the air flow reversing system and the regenerative chamber reversing system. When the temperature of at least a part of the hearth reaches above the fuel self-ignition temperature, all the burners are continuously and uninterruptedly working or are switched in turn until the heating is completed.

[0025] The auxiliary structure of the industrial furnace with diffuse regenerative combustion of the present application is consistent with that of the existing industrial furnace with diffuse regenerative combustion, and further comprises a blower, an induced draft fan, a computer control system, etc. The hearth is composed of a hearth roof, hearth walls and a hearth bottom.

[0026] The diffused heat accumulation combustion industrial furnace of the present application is a safe and super high efficiency diffused heat accumulation combustion system. It is well known that there are two conditions for fuel explosion: one is the accumulation of fuel and oxygen mixture in the explosion concentration range, and the other is the ignition of the open flame (including sparks). Taking the heat accumulation combustion system with 2 heat accumulation boxes + 2 burners as an example, after improvement, the two burners work simultaneously, the range of open flame covering the furnace is greatly expanded, and the combustible gas is continuously ignited and consumed. One is to greatly reduce the accumulation of explosive gas, and the other is to eliminate the ignition step of the accumulated explosive gas by the flame suddenly sprayed from the starting burner during the switching process of the burner. Therefore, compared with the traditional diffused heat accumulation combustion system of Comparative Example 2, because the two elements of explosion are eliminated, the technical problem of explosion can be solved, and the safety will be higher.

[0027] At the same time, compared with the traditional diffused heat accumulation combustion system of Comparative Example 2, at the initial stage of the low temperature stage, the actual power of each burner can be higher than that of the traditional diffused heat accumulation combustion system (because the explosion problem is solved, and the traditional diffused heat accumulation combustion system must greatly reduce the power of the burner to consider the explosion problem), the two burners work simultaneously, the actual power will be higher, and there is no switching interval time caused by the switching of the burner, the actual power will also be higher. Overall, the diffused heat accumulation combustion industrial furnace of the present application has higher power and higher working efficiency.

[0028] And because the burner corresponding to the heat accumulation box of the exhaust flue gas in the premixing heat accumulation combustion system must stop working, and the working burner must stop working in advance during the gas flow switching process, the diffused heat accumulation combustion system of the present application cannot realize the state that all burners work simultaneously and the burners do not need interval time and do not need to stop working during the gas flow switching process. Compared with the two, under the same conditions, the average power output of the diffused heat accumulation combustion system of the present application is not only much higher than that of the prior art diffused heat accumulation combustion system, but also higher than that of all premixing heat accumulation combustion systems. Specifically, after using the latest use method, at the most severe low temperature stage of the diffused heat accumulation combustion system, the total power of the system can be increased to more than 4 times that of the existing diffused heat accumulation combustion system at the same stage, and more than 1.5 times that of the premixing heat accumulation combustion system, completely solving the problem of slow production speed of the prior art.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. The diffuse heat accumulation combustion industrial furnace of the present application, in the low-temperature stage where the temperature in the furnace chamber does not reach the fuel self-ignition temperature, at least two burners keep continuous and uninterrupted operation for some time or the whole time period, the range of open flame covering the furnace chamber is greatly expanded, the amount of accumulated explosive gas is greatly reduced, and there is no step of igniting the accumulated explosive gas by the flame spouted by the burner that starts to work during the burner switching process, thus completely eliminating the risk of explosion in the diffuse heat accumulation combustion system, and the safety is obviously higher.

[0031] 2. In the most severe low-temperature stage of the diffuse heat accumulation combustion system, the total power of the system can be increased to more than 4 times that of the existing diffuse heat accumulation combustion system at the same stage, the production efficiency is obviously higher, and the problem of slow production speed in the prior art is completely solved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Fig. 1 is a structural schematic diagram of a premix heat accumulation combustion system.

[0034] Fig. 2 is a working schematic diagram of the existing diffuse heat accumulation combustion system when the material is full.

[0035] Fig. 3 is a working schematic diagram of the existing diffuse heat accumulation combustion system after the material is melted.

[0036] Fig. 4 is a working schematic diagram of the present application when the material is full.

[0037] Fig. 5 is a schematic diagram of the arrangement of the heat accumulation box and the burners of the present application.

[0038] Fig. 6 is a working schematic diagram of the present application after the material is melted.

[0039] Fig. 7 is a working schematic diagram of the present application when 2 heat accumulation boxes + 3 burners are used when the material is full.

[0040] Legend: 1, furnace chamber; 4, combustion chamber; 5, ignition gun; 6, auxiliary air inlet; 7, burner; 701, first burner; 702, second burner; 703, third burner; 8, fuel inlet; 9, main air passage; 10, heat accumulation box; 1001, first heat accumulation box; 1002, second heat accumulation box; 11, heat accumulation material; 14, material. DETAILED DESCRIPTION

[0041] For the purpose of facilitating the understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0042] It should be particularly noted that when an element is described as being "fixed to, attached to, connected to or communicated with" another element, it can be directly fixed, attached, connected or communicated with the other element, or indirectly fixed, attached, connected or communicated with the other element through other intermediate connecting elements.

[0043] Unless otherwise defined, all the professional terms used below have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0045] The present application fundamentally solves the safety and efficiency problems of the industrial furnace of the dispersion type heat accumulating combustion system. In order to more clearly illustrate the difference between the present application and the prior art in the above-mentioned safety and efficiency aspects, two typical prior art cases (Comparative Examples 1-2) are introduced first. Then, through the operation comparison of the embodiment of the present application and Comparative Examples 1-2, the perfect operation effect of the present application can be better understood.

[0046] Comparative Example 1:

[0047] FIG. 1 is a side view schematic diagram of a 35-ton aluminum alloy smelting furnace using the conventional premix type heat accumulating combustion system technology in the prior art. The fuel is natural gas, and the system is composed of a hearth 1, a heat accumulating tank 10 (including a first heat accumulating tank 1001 and a second heat accumulating tank 1002), heat accumulating materials 11 filled in the heat accumulating tank 10, a combustion chamber 4, a main air passage 9 connected between the heat accumulating tank 10 and the combustion chamber 4, a burner 7 (including a first burner 701 and a second burner 702), an ignition gun 5, a fuel inlet 8, an auxiliary air inlet 6, a blower, an induced draft fan, an air flow reversing system and a computer control system. The hearth 1 is composed of a furnace wall, a furnace top and a furnace bottom, and the combustion chamber 4 is in communication with the hearth 1. In order to make the schematic diagram simple, the blower, the induced draft fan, the air flow reversing system and the computer control system are not shown in the figure.

[0048] Production requirements: The material 14 (about 35 tons of solid aluminum or aluminum alloy raw material) is melted and heated to about 730-760℃, the combustion system works for less than 5 hours, and the air flow reversing time period is 60 seconds. FIG. 1 shows the case when the aluminum material has been heated to above 660℃ and is in a liquid state.

[0049] The working process is as follows: the long-lasting fire of the two ignition guns 5 is ignited when the combustion system starts to work and is not extinguished. The heat storage material 11 in the first heat storage box 1001 heats the secondary combustion air and sends the secondary combustion air into the combustion chamber 4 through the main air passage 9. The fuel in the fuel inlet 8 and the auxiliary air inlet 6 enter the primary air in the first burner 701 and are sprayed into the combustion chamber 4 to be ignited by the long-lasting fire of the ignition gun 5; the unburned fuel continues to mix with the secondary combustion air in the combustion chamber 4 and is completely burned. The natural gas supplied to the first burner 701 per hour is 450 Nm 3 If the heat value of the natural gas is 35000 kJ / Nm 3 , the power of the first burner 701, i.e. the heat provided by the first burner 701 to the system per hour, is 35000 kJ / Nm 3 × 450 Nm 3 / hour = 15750000 kJ / hour = 4375 kW, which is the maximum power of the first burner 701 of the present comparative example. For convenience, the power of the burner 7 or the combustion system is expressed by the amount of natural gas (Nm 3 / hour) in the present application. The fuel, the primary air and the secondary combustion air are converted into super-high-temperature flue gas and the tail of the flame in the combustion chamber 4, which enters the furnace 1 to heat the aluminum alloy material. The flue gas passes through the combustion chamber 4, the main air passage 9, and then enters the second heat storage box 1002, passes through the heat storage material 11 and is discharged from the system by the induced draft fan. During the above process, the second burner 702 does not work. After one cycle 60 seconds of the reversing system, the whole system switches to operate according to the rules of the regenerative combustion system: the first burner 701 is closed, the air flow reversing system switches the direction of the air flow, i.e. the secondary combustion air is heated by the heat storage material 11 in the second heat storage box 1002, enters the combustion chamber 4 from the main air passage 9; the flue gas 3 passes through the combustion chamber 4, the main air passage 9, and then enters the first heat storage box 1001, passes through the heat storage material 11 and is discharged from the system by the induced draft fan. After the air flow is switched, the second burner 702 starts to work, and the interval time is 2 seconds.

[0050] It is assumed that the system energy consumption of each comparative example and embodiment is 60 Nm 3 / ton, and the power of the burner 7 is 450 Nm 3 / hour. In the present system, the total amount of natural gas required for 35 tons is 2100 Nm 3 . Considering the influence of the 2-second interval time when the burner 7 is extinguished, the system reference average power is 435 Nm 3 / hour. It takes 4.82 hours to complete one furnace production, which can exactly meet the requirement that the working time of the combustion system for one furnace does not exceed 5 hours.

[0051] In order to facilitate explanation and accurate comparison, all the comparative examples and embodiments are explained based on the present comparative example. Among them:

[0052] System reference average power: is the ratio of the total amount of energy consumed by each furnace and the longest time to meet the speed requirements. The system reference average power of the present comparative example is 435 Nm 3 The actual power of the burner 7 is the ratio of the amount of fuel injected by the burner 7 and the time used to inject the fuel. The system average power is the ratio of the energy consumed in a certain stage and the time of this stage (the time needs to be greater than one switching cycle). The system average power can be higher or lower than the system reference average power.

[0053] Comparative Example 2:

[0054] Figure 2 is a 35-ton aluminum alloy melting furnace using the conventional dispersed regenerative combustion system technology. The processed material 14 is a solid low-temperature stage. The system components and operating requirements are the same as those of the system of Comparative Example 1 (Figure 1) (except for the different places mentioned later). The system reference average power is 435 Nm 3 / hour. Since it is a dispersed combustion, the installation positions of the first burner 701 and the second burner 702 are different from those of Comparative Example 1 (Figure 1), and there is no combustion chamber 4 as in Comparative Example 1 (Figure 1).

[0055] In the present comparative example, the first burner 701 is working, the secondary combustion air enters the furnace 1 through the main air passage 9, and the remaining fuel injected into the furnace 1 by the first burner 701 mixes with the secondary combustion air to form a flame in the furnace 1. The rest of the operation method is the same as that of the system of Comparative Example 1. After 60 seconds, the entire system switches to operation according to the rules of the regenerative combustion system: the first burner 701 is closed, and the gas flow direction is switched in the same way as the system in Comparative Example 1. After the gas flow switching is completed, the second burner 702 starts to work.

[0056] The present comparative example does not have a special combustion chamber 4, but uses the furnace 1 filled with aluminum materials as the main combustion chamber. The furnace 1 is filled with aluminum materials, and the aluminum materials block the space of the furnace 1, resulting in a very limited space for combustion. The fuel injected by the first burner 701 working in cooperation with the main air passage 9 cannot burn after encountering the aluminum materials and enters the gaps in the low-temperature aluminum materials. The flame will be extinguished when it passes through the low-temperature aluminum materials due to the low temperature, and the fuel will accumulate in the gaps in the aluminum materials and form an explosive gas. The first burner 701 works at a power of 450 Nm 3 / hour, and the total amount of explosive gas accumulated in the gaps in the aluminum materials will be very large. The first burner 701 is extinguished first, and the other second burner 702 starts to work after the gas flow switching system is completed. The switching interval time of the burner 7 is about 2 seconds, and during this time the fuel in the gaps in the aluminum materials just mixes uniformly with the oxygen. Due to the short interval time, most of the accumulated mixed explosive gas does not exit the furnace 1, and the flame injected by the second burner 702 will ignite the unburned explosive gas accumulated in the low-temperature aluminum materials, resulting in an explosion.

[0057] In order to prevent fuel from gathering in large quantities in the gaps of the aluminum material and to prevent the potential risk of deflagration of the system, the power of the burner 7 must be greatly reduced in the initial stage of the low-temperature stage when the temperature of the material 14 is low. The working power of the burner 7 in the present comparative example is selected to be 90 Nm / h, which is equivalent to 20.69% of the reference average power of the system. 3 The interval time is 8 seconds, and the actual average power of the system is 78 Nm / h, which is 17.9% of the reference average power of the system. After about 20 minutes of running in the first stage of the low-temperature stage, the temperature of the furnace 1 gradually rises, and the second stage is entered; in the second stage, the working power of the burner 7 is increased to 150 Nm / h, and the actual average power of the system is 130 Nm / h. 3 3 3 3 3 3 3 3 3

[0058] Taking into account the effect of the burner 7 stopping firing in the interval time of 8 seconds, the average power of the system in the first 120 minutes after starting is 229 Nm / h, which is less than 53% of the reference average power of the system of 435 Nm / h, and the total output heat is 394.33 Nm / h, which is the calorific value of natural gas. 3 3 3 The average power of the system in the first 2 hours is greatly lower than the reference average power of the system.

[0059] Figure 3 is a schematic diagram of the operation of the dispersion-type regenerative aluminum melting furnace after the material 14 in the furnace 1 is completely melted and flattened, at which time the power of the burner 7 is equal to the reference power of the burner 7 of 450 Nm / h. 3

[0060] ​​​​​​​​​​​​In summary, the dispersion type heat accumulation combustion system has only completed about half of the heating work of the system under the average power of the reference in the first 120 minutes. Even in the 4 hours of high temperature stage, the burner 7 operates at a power of 450 Nm 3 / hour, and the combustion system outputs 2100 Nm 3 / hour of natural gas heat value, which takes a total time of 5.92 hours, which cannot meet the requirement of completing the task in 5 hours of operation of the combustion system. On the other hand, extending the interval time does not eliminate the accumulation of explosive gas, but only uses the continuous operation of the blower and the induced draft fan during the interval time to discharge part of the explosive gas through the induced draft fan to the furnace 1, which does not completely eliminate the risk of explosion.

[0061] As can be seen from Comparative Example 1 and Comparative Example 2, no matter in the operation mode of the dispersion type heat accumulation combustion system or in the operation mode of the premix type heat accumulation combustion system, the burner 7 is reversed with the air flow reversing system, and adopts the operation mode of working and stopping work cycle switching.

[0062] Example 1:

[0063] A 35-ton aluminum melting furnace using natural gas fuel, as shown in FIG. 4, the system composition and requirements are basically the same as the dispersion type heat accumulation combustion system in Comparative Example 1 (FIG. 2).

[0064] In FIG. 4, the difference from Comparative Example 2 is: ①, the fuel inlet 8 of the burner 7 (including the first burner 701 and the second burner 702) simultaneously inputs fuel, and the fuel simultaneously enters the first burner 701 and the second burner 702 to mix with the primary air, and the outlets of the first burner 701 and the second burner 702 simultaneously spray out the flame and the remaining fuel. The remaining fuel from the first burner 701 and the second burner 702 enters the furnace 1 and mixes with the secondary combustion air in the main air passage 9 to burn. ②, after one cycle of 60 seconds of the air flow reversing system, the entire system does not operate according to the rule of the traditional heat accumulation combustion system - the air flow and the burner are reversed at the same time, but only the air flow is switched. After the air flow is switched, the secondary combustion air is heated by the heat accumulation material 11 in the first heat accumulation tank 1001, enters the furnace 1 from the main air passage 9; the flue gas 3 passes through the main air passage 9, then enters the second heat accumulation tank 1002, and is discharged from the system by the induced draft fan through the heat accumulation material 11. No matter before or after the air flow is switched or during the interval time, the first burner 701 and the second burner 702 do not stop working, so the first burner 701 and the second burner 702 do not have the process of stopping and starting work and the interval time problem.

[0065] The first burner 701 and the second burner 702 of the embodiment continuously spray the flame and the residual fuel into the furnace 1, and the coverage of the two continuously existing flames near the material 14 gap near the outlet of the first burner 701 and the second burner 702 is much larger than that when only the first burner 701 or the second burner 702 works, and the combustible gas can be continuously and stably ignited in the larger range and cannot form accumulation; on the other hand, the first burner 701 and the second burner 702 do not have the action of stopping and restarting, and the sudden spray of the open flame to ignite the combustible gas. This eliminates two prerequisites for deflagration from two aspects, so that the system safety performance of the embodiment is high and cannot deflagrate.

[0066] Fig. 6 is a working condition after the solid material 14 is melted and leveled in the embodiment.

[0067] The present application changes the working mode of the first burner 701 and the second burner 702 in the existing regenerative combustion technology from turn-by-turn to two or more burners 7 working at the same time, solves the deflagration problem and improves the production efficiency. However, it brings different degrees of insufficient combustion problem under different circumstances. The following embodiments introduce these insufficient combustion problems and technical means to solve these problems.

[0068] Embodiment 2:

[0069] As shown in Fig. 4, the spatial layout of the two regenerative chambers 10 (the first regenerative chamber 1001 and the second regenerative chamber 1002) and the two burners 7 (the first burner 701 and the second burner 702) meets the requirement that when the regenerative chamber 10 and the burner 7 are located on the same side of the furnace 1, the burner 7 is located between the regenerative chambers 10, that is, the fuel sprayed by the burner 7 far away from the regenerative chamber 10 inputting the secondary combustion air has the secondary combustion air passing through to help its full combustion. In the embodiment, the two burners 7 (the first burner 701 and the second burner 702) are located in the middle of the two regenerative chambers 10 (the first regenerative chamber 1001 and the second regenerative chamber 1002).

[0070] In the regenerative combustion technology, a flow field is formed between the regenerative chamber 10 where the secondary combustion air is input and the regenerative chamber 10 where the exhaust gas is discharged. In the traditional diffusion regenerative combustion technology, as shown in Fig. 3, one regenerative chamber 10 corresponds to one burner 7, so the burner 7 can ensure sufficient combustion as long as the burner 7 is at a proper distance from the regenerative chamber 10 where the exhaust gas is discharged, even if the burner 7 is not in the flow field. In the present application, as shown in Fig. 4, the secondary combustion air input into one regenerative chamber 10 needs to be supplied to two or more burners 7; if a burner 7 that is far away from the regenerative chamber 10 where the secondary combustion air is input is not located in the flow field, the fuel injected into the furnace 1 by the burner 7 can be drawn away by the regenerative chamber 10 where the exhaust gas is discharged before being mixed with the secondary combustion air, which cannot effectively mix and burn with the secondary combustion air, resulting in insufficient combustion. In order to avoid this situation, the distance between two regenerative chambers 10 is far, that is, the fuel injected by the burner 7 that is far away from the regenerative chamber 10 where the secondary combustion air is input has the secondary combustion air to assist its sufficient combustion before entering the regenerative chamber 10 where the exhaust gas is discharged.

[0071] The burner arrangement in Fig. 2 (i.e. Comparative Example 2) is not the preferred solution. In Fig. 2, if the first burner 701 is allowed to work, the second burner 702 is also allowed to work. The fuel input into the furnace 1 by the second burner 702 has little chance to mix with the secondary combustion air input into the first regenerative chamber 1001 and enters the second regenerative chamber 1002 in the exhaust gas state, which cannot complete the combustion (it is worth emphasizing that although the solution in Fig. 2 is not the preferred solution, the two burners 7 working at the same time can still solve the technical problem of the present application to some extent). However, by using the structure of the present embodiment as shown in Fig. 4, the air input from the outlet of the first regenerative chamber 1001 gradually participates in the combustion and is discharged from the outlet of the second regenerative chamber 1002, so the gas flow naturally passes through the outlet of the second burner 702, assisting the sufficient combustion of the second burner 702.

[0072] Example 3:

[0073] As shown in Fig. 5, another spatial arrangement of two regenerative chambers 10 and two burners 7 meets the requirement that "when two regenerative chambers 10 and two burners 7 are located on different sides of the furnace 1, the connecting lines of the two regenerative chambers 10 and the two burners 7 form a quadrilateral, and the two regenerative chambers 10 are located on one pair of opposite corners of the quadrilateral, and the two burners 7 are located on the other pair of opposite corners, that is, the fuel injected by the burner 7 that is far away from the regenerative chamber 10 where the secondary combustion air is input has the secondary combustion air to assist its sufficient combustion". In the present embodiment, the two burners 7 and the two regenerative chambers 10 occupy four position points, and the two regenerative chambers 10 are located at the opposite corners in the rectangle formed by the four position points.

[0074] Example 4:

[0075] The low-temperature stage material 14 occupies the space of the furnace 1, and too much natural gas fuel is fed into the furnace 1, which can cause the consequences of insufficient combustion and increased energy consumption. Therefore, the power of each burner 7 in the initial stage of the low-temperature stage is preferably not more than 40% of the reference power of the burner 7. The system average power in this stage is lower than the system reference average power, but the system average power can be greater than the system reference average power in the subsequent stage, so as to meet the production speed requirement as a whole.

[0076] Specifically, the embodiment is an optimization of the embodiments 1 to 3. In the cold furnace stage when the material 14 is just put in, the actual power of the burner 7 is set to be lower than 40% of the system reference average power 435 Nm 3 / hour for 10-20 minutes. Specifically, the power of the two burners 7 is set to 160 Nm 3 / hour, and the actual power of a single burner 7 is 36.78% of the system reference average power, which is less than 40%. The two burners 7 work at the same time, and the total actual power of the system is 320 Nm 3 / hour, which is 73.56% of the system reference average power 435 Nm 3 / hour. The system average power in this stage is lower than the system reference average power; the purpose of this optimization is to ensure the energy efficiency of the system in the low-temperature stage.

[0077] Embodiment 5:

[0078] In the regenerative combustion technology, the primary air is involved in combustion without being heated by the regenerator 10, and the secondary combustion air is heated by the regenerator 10 and enters the furnace 1 to participate in combustion at a temperature of more than 1000℃. If the proportion of the primary air is too large, it is not energy-saving. Therefore, the regenerative combustion system tries to pursue the minimum proportion of the primary air under the premise of safety.

[0079] The embodiment is a further optimization of the embodiment 4. In the low-temperature stage when the material 14 is just put in, even if the power of each burner 7 is set to be not more than 40% of the system reference average power, the system average power in this stage is lower than 80% of the system reference average power. Due to the fact that the material 14 occupies the space of the furnace 1 and blocks the mixing of the secondary combustion air and the fuel, the mixing sufficiency cannot be compared with that of the primary air and the fuel. This can also cause the consequences of insufficient combustion and increased energy consumption in the furnace 1. In comparison, the energy waste caused by insufficient combustion is much greater than the energy waste caused by the primary air without being heated to participate in combustion, especially in the low-temperature stage, the temperature to which the secondary combustion air can be heated is only 200-500℃. Therefore, in order to save energy, increasing the proportion of the primary air in the low-temperature stage so that the fuel can be close to complete combustion near the burner 7 and its outlet is a preferred means for reducing insufficient combustion in the present application.

[0080] The first stage of the low temperature stage in the embodiment 4, provides the primary air volume 1520 Nm 3 / hour, about 50% of the theoretical oxygen required for the total fuel of the system 2 burner 7. The proportion of the primary air in the total air supply is much higher than that of the prior art.

[0081] Embodiments 4 and 5, in the first 10 minutes after firing, a total of 53.33 m 3 Natural gas is consumed, which is equivalent to 32.6 minutes of total power output of Comparative Example 2, which greatly improves the production speed. Compared with 72.5 Nm 3 Natural gas is consumed in the first 10 minutes of Comparative Example 1, the total power output is only 19.16 Nm 3 Although there is a gap, this gap can be compensated for in 8.8 minutes when the invention enters the high temperature stage and the two burners 7 work simultaneously, assuming that each burner 7 works at about 65% of the system's average power. This is negligible for the subsequent heating process of more than 4 hours.

[0082] In fact, all the previous examples can be run in the first stage of the low temperature stage for 10-20 minutes and then enter the second stage of the low temperature stage, and the total power of the system is increased to 400 m 3 / hour. The local area temperature near the outlet of the burner 7 in the furnace 1 can reach higher than the self-ignition temperature of natural gas. At this time, the total power of the system can be increased to more than 435 Nm 3 / hour of the system's average power to ensure production speed.

[0083] If the two stages of the low temperature stage are 20 minutes, and each burner 7 in the high temperature stage is operated at 55% of the system's average power, i.e. the total power of the system is 478.5 Nm 3 / hour, the average power of the system in the high temperature stage is 10% higher than the system's average power. The total running time is: 40÷60+(2100-(320+400)×20÷60)÷478.5=4.55 hours, which only takes 4.55 hours to complete the production task in advance.

[0084] Embodiment 6:

[0085] As shown in Figure 7, this embodiment is based on the embodiment 1 and adds one burner 7 (adding a third burner 703), which is a 2-heat storage tank 10+3-burner 7 mode. The distance between the two heat storage tanks 10 is greater than the distance between the other two combinations, which is manifested as the three burners 7 being located between the two heat storage tanks 10. The three burners 7 work simultaneously and uninterruptedly. In the cold furnace stage just after the material 14 is put in, the power of the burner 7 is set to be lower than the system's average power 435 Nm3 40% for about 20 minutes. Specifically, the power of each burner 7 is set to 160 Nm 3 / hour, which is 36.78% of the reference power of the burners 7, less than 40%. The total system power is 480 Nm 3 / hour, which is the reference average power of the system 435 Nm 3 110.3% of 480 Nm 3 / hour, the total system power is 675 Nm 3 / hour, which is the reference average power of the system 435 Nm 3 155% of 480 Nm

[0086] The average power of each stage of the system in this embodiment is higher than the reference average power of the system, and it only takes less than 3.5 hours to complete the production task, which shows that the production speed is greatly improved.

[0087] In real production tests, we used the technical solution of 2 burners 7 + 2 regenerative boxes 10 to achieve the task of completing 35 tons of aluminum alloy smelting in 3.5 hours for a long time.

[0088] The low-temperature stage of the traditional dispersion regenerative combustion technology (Figures 2 and 3) usually needs to be divided into 3-5 sub-stages, and the system operating parameters are gradually adjusted as the temperature increases over time. However, the low-temperature stage of the present invention only needs 1-2 steps. In the initial stage of the low-temperature stage, the local temperature of the local area around the burner 7 outlet can usually be raised to the self-ignition temperature of the fuel within 10-20 minutes. Therefore, the specific running time of the initial stage of the low-temperature stage can be determined according to the specific system operation to achieve the time before and after the local temperature of the local area reaches the self-ignition temperature of the fuel. The larger the local area that reaches the self-ignition temperature of the fuel, the greater the power increase in the subsequent stage; the smaller the local area, the less the power increase. The running time of this initial stage can also be extended until most of the furnace 1 area temperature exceeds the self-ignition temperature of the fuel, and the high-temperature stage is directly entered, which is the case where the low-temperature stage only needs 1 step.

[0089] The time when the two burners 7 in the low-temperature stage of the above embodiment work simultaneously can be selected according to actual conditions, such as working simultaneously in the first half of the low-temperature stage, or working simultaneously throughout the low-temperature stage.

[0090] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the technical solutions recorded in the above examples can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0091] For example:

[0092] In the embodiments 1-5, two burners 7 can work simultaneously in the low-temperature stage, but in the high-temperature stage, the existing burner 7 is used to switch the working mode alternately when the furnace 1 is higher than 700℃; in the embodiment 6, three burners 7 can work simultaneously in the low-temperature stage, and in the high-temperature stage, the middle burner 7 stops working and the other two burners 7 work simultaneously without stopping.

Claims

A diffuse regenerative combustion industrial furnace comprising a furnace chamber (1), a gas flow reversing system and at least two regenerative chambers (10), said furnace chamber (1) being provided with burners (7) mounted thereon, characterized in that, The burner (7) is provided with at least two burners (7), and at least two burners (7) are continuously and uninterruptedly operated in a first time period in a low temperature stage, wherein the low temperature stage refers to a time period when the temperature in the furnace (1) is below the fuel self-ignition temperature. The diffuse regenerative combustion industrial furnace according to claim 1, characterized in that, The low temperature stage includes a time period from the start of heating the furnace (1) by the burner (7) to the end of the operation of the burner (7) for 10-60 minutes, and at least two burners (7) are continuously and uninterruptedly operated in the time period. The diffuse regenerative combustion industrial furnace according to claim 1, characterized in that, The secondary combustion air heated by the regenerative chamber (10) enters the furnace (1) through the main air passage (9), the inlet of the burner (7) is connected with the fuel inlet (8), the outlet of the burner (7) is used for spraying the flame and the fuel into the furnace (1), and the regenerative chamber (10) is arranged close to the burner (7) to ensure that the secondary combustion air provided by the regenerative chamber (10) can be supplied to all burners (7) in operation, thereby promoting the full combustion of the fuel sprayed by the burner (7). The diffuse regenerative combustion industrial furnace according to claim 1, wherein When the regenerative chamber (10) and the burner (7) are located on the same side of the furnace (1), the burners (7) are located between the regenerative chambers (10). The diffuse regenerative combustion industrial furnace according to claim 1, wherein When the two regenerative chambers (10) and the two burners (7) are located on different sides of the furnace (1), the connecting lines of the two regenerative chambers (10) and the two burners (7) form a quadrilateral, and the two regenerative chambers (10) are located on one diagonal of the quadrilateral, and the two burners (7) are located on the other diagonal of the quadrilateral. The diffuse regenerative combustion industrial furnace according to any one of claims 1-5, characterized in that, In the low temperature stage, the actual power of the burners (7) continuously and uninterruptedly operated in at least one first time period is not greater than 40% of the system reference average power, the actual power of the burners (7) is the ratio of the amount of fuel sprayed by the burners (7) to the time for spraying the fuel, and the system reference average power is the ratio of the total amount of fuel consumed by each furnace product to the working time for consuming the total amount of fuel. The diffuse regenerative combustion industrial furnace according to claim 6, characterized in that The start of the first time period is the start of the low temperature stage. The diffuse regenerative combustion industrial furnace according to any one of claims 1-5, characterized in that, In the low temperature stage, the oxygen volume in the total primary air provided in the auxiliary air inlets (6) of the burners (7) continuously and uninterruptedly operated in at least one second time period is v1, the volume of the theoretical oxygen required for the combustion of all the fuel sprayed by all the burners (7) is v2, and v1 / v2 is not less than 35%. The diffuse regenerative combustion industrial furnace according to claim 8, characterized in that The start of the second time period is the start of the low temperature stage. A heating method of heating a material by the diffuse heat accumulation combustion industrial furnace according to any one of claims 1 to 9, characterized by, The method comprises the following steps: The furnace (1) is filled with materials, and the burners (7) are used to spray the flame and the fuel into the furnace (1) for heating the materials filled in the furnace (1), and all the burners (7) are continuously and uninterruptedly operated in a first time period in a low temperature stage, and are not affected by the air flow reversing system and the regenerative chamber (10) reversing; after the temperature of at least a part of the area in the furnace (1) reaches above the fuel self-ignition temperature, all the burners (7) are continuously and uninterruptedly operated or are switched in turn until the heating is completed.

Images