Regenerative burner with variable cross section for adjusting Reynolds number and magnesium smelting device with burner

Abstract

The invention belongs to the technical field of regenerative burners, and discloses a regenerative burner with a variable cross section to adjust Reynolds number and a magnesium smelting device with the same, the regenerative burner comprises a burner box body, a middle partition is arranged in the burner box body to divide the burner box body into a first accommodating chamber and a second accommodating chamber, heat exchange units are arranged in the first accommodating chamber and the second accommodating chamber respectively, and the heat exchange units are arranged in the first accommodating chamber and the second accommodating chamber respectively. The heat exchange unit is formed by stacking a plurality of heat accumulators in an array mode, through holes which are evenly distributed in an array mode are formed in the heat accumulators, the through holes among the heat accumulators are sequentially communicated from outside to inside to form gas channels, and the cross sections of the gas channels are sequentially increased from outside to inside. The cross sections of the gas channels are sequentially increased from outside to inside, the stability of the Reynolds number Re is basically maintained, heat exchange uniformity is guaranteed, and the heat exchange efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of magnesium smelting equipment, and specifically relates to a regenerative burner with variable cross-section to adjust the Reynolds number and a magnesium smelting equipment having the burner. Background Technology

[0002] The regenerative burners in the magnesium reduction furnace consist of multiple pairs of burners installed on both sides of the furnace body. Each burner contains a regenerator (ceramic balls) or regenerator bricks. Each burner is connected to two pipelines: one for combustion air and one for combustion gas. These two pipelines are then connected to the intake and exhaust pipelines via four-way reversing valves. The working process involves mixing air and combustion gas, which is then ignited and ejected from the burners. The multiple burners on both sides are used alternately, serving as either the exhaust or intake channel. During combustion, the paired regenerator chambers alternately absorb and release heat, ensuring full heat recovery and utilization. In the dual regenerative burner system, the combustion gas and air reach a higher preheated temperature before entering the combustion zone, resulting in more complete combustion and a more uniform flame temperature. This helps to increase and stabilize the furnace temperature, promoting magnesium reduction.

[0003] In the operation of regenerative burners used in magnesium reduction furnaces, flue gas flows out of the furnace through one of the burners, transferring heat to the regenerator of the burner for heat storage. After passing through the burner, the flue gas temperature drops sharply from high temperature to low temperature, causing the flue gas volume to shrink and the flow velocity to decrease. In the low temperature range, the Reynolds number (Re) often drops to the laminar flow region (Re<2300), and the convective heat transfer coefficient decreases significantly. Existing solutions (such as fixed cross-section honeycomb, staged regenerators, or commutation cycle optimization) still cannot maintain a relatively stable Re, thus limiting the low-temperature heat recovery efficiency of the regenerator.

[0004] On the other hand, at the same time, the combustion air and gas flow into the magnesium reduction furnace through another burner. The heat storage body transfers the stored heat to the combustion air and gas for preheating. The preheated combustion air and gas expand in volume and increase in flow velocity, which is unstable. This leads to a significant increase in Re and instability (the flow state fluctuates between laminar and turbulent flow), which in turn causes problems such as fluctuation in heat transfer efficiency and uneven temperature distribution.

[0005] Thirdly, since the heat exchange medium is gas, changes in its volume, flow rate, temperature, etc. after heat exchange will cause changes in the Reynolds number (Re). Currently, existing regenerative burners have a large overall volume, unreasonable structure, low overall heat exchange efficiency, high manufacturing and maintenance costs, and contain a lot of useless heat storage materials, which cannot adapt to the impact of the above-mentioned changes in parameters after gas heat exchange on heat exchange efficiency. Summary of the Invention

[0006] The purpose of this invention is to propose a regenerative burner with variable cross-section to adjust the Reynolds number and a magnesium smelting device with the burner. It solves the problem of poor heat exchange caused by the instability of gas volume, temperature, flow rate and Reynolds number Re during the heat exchange flow of flue gas, combustion air and fuel gas in the prior art. Through special improvement of the gas channel with variable cross-section, the Reynolds number Re is basically maintained, ensuring the uniformity of heat exchange and improving the heat exchange efficiency.

[0007] The technical solution adopted to achieve the above objectives is: A regenerative burner with variable cross-section to adjust Reynolds number includes a burner housing, which is divided into a first housing chamber and a second housing chamber by an intermediate partition. Both the first and second housing chambers are equipped with heat exchange units. Each heat exchange unit is composed of an array of heat storage elements stacked together. The heat storage elements are provided with an array of evenly distributed through holes. The through holes between the multiple heat storage elements are connected sequentially from the outside to the inside to form a gas channel. The cross-section of the gas channel increases sequentially from the outside to the inside.

[0008] Preferably, an air inlet end 1 connected to a gas passage is installed on the outside of the first receiving chamber, an air outlet end 1 connected to a gas passage is installed on the inside of the first receiving chamber, an air inlet end 2 connected to a gas passage is installed on the outside of the second receiving chamber, and an air outlet end 2 connected to a gas passage is installed on the inside of the second receiving chamber.

[0009] Preferably, the heat exchange unit is divided into N heat storage unit groups from the outside to the inside, namely the first heat storage unit group, the second heat storage unit group, ..., the Nth heat storage unit group, etc. The number of heat storage elements in the N heat storage unit groups increases sequentially. A buffer chamber is provided between two adjacent heat storage unit groups. The buffer chamber is used to connect the gas channels of the two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area.

[0010] Preferably, the heat exchange unit is divided into M heat storage unit groups from bottom to top: a first heat storage unit group, a second heat storage unit group, ..., an Mth heat storage unit group, etc. The number of heat storage elements in the M heat storage unit groups increases sequentially. The transition points of the M heat storage unit groups are connected sequentially through buffer chambers. The buffer chambers are used to connect the gas channels of two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area that winds upwards.

[0011] Preferably, an inlet buffer chamber is provided at the outer end of the first heat storage unit group, and an outlet buffer chamber is provided at the inner end of the innermost heat storage unit group. Both the inlet buffer chamber and the outlet buffer chamber are connected to the gas channel. The first air inlet and the second air inlet are respectively connected to the corresponding inlet buffer chambers, and the first air outlet and the second air outlet are respectively connected to the corresponding outlet buffer chambers. The first air outlet and the second air outlet converge at the main air outlet.

[0012] Preferably, the burner housing is filled with a solid heat storage body, the solid heat storage body having a complementary shape to the heat exchange unit to fill the space inside the burner housing.

[0013] Preferably, the burner box is filled with refractory mortar, which fills the gaps between the various heat storage elements to ensure the airtightness of the gas passage.

[0014] A magnesium smelting apparatus having a regenerative burner as described above includes a magnesium reduction furnace, a combustion air source, a gas source, a first four-way reversing valve, a first induced draft fan, a second four-way reversing valve, and a second induced draft fan. The combustion air source, the first four-way reversing valve, and the first induced draft fan are connected in sequence through a first pipeline, and the gas source, the second four-way reversing valve, and the second induced draft fan are connected in sequence through a second pipeline. Both the first induced draft fan and the second induced draft fan are connected to a chimney. Two regenerative burners are symmetrically installed on the left and right sides of the magnesium reduction furnace, referred to as the left burner and the right burner respectively. The first and second air inlets of the left burner are connected to the first and second four-way reversing valves through pipes, respectively. Similarly, the first and second air inlets of the right burner are connected to the first and second four-way reversing valves through pipes, respectively.

[0015] Preferably, when the left burner receives combustion air and gas and the right burner receives flue gas, the combustion air source delivers combustion air through a pipeline and then through the first four-way reversing valve into the first air inlet of the left burner, and the gas source delivers gas through a pipeline and then through the second four-way reversing valve into the second air inlet of the left burner. After being preheated by the left burner, the gas is mixed and then enters the magnesium reduction furnace. The flue gas in the magnesium reduction furnace transfers heat to the right burner when it passes through the right burner, and then enters the chimney after passing through the first and second inlet ports of the right burner and the first and second four-way reversing valves respectively. When the right burner receives combustion air and gas, and the left burner emits flue gas, the same applies to the left burner; the above actions are repeated alternately.

[0016] The beneficial effects of this invention are as follows: (1) By redesigning and arranging the heat storage body inside the burner, the cross-section of the gas channel is gradually increased from the outside to the inside, which solves the problem of poor heat exchange caused by temperature rise and fall, flow velocity rise and fall, and unstable Reynolds number Re during the heat exchange flow of flue gas, combustion air and gas in the prior art. Through the special improvement of the variable cross-section of the gas channel, the stability of the Reynolds number Re is basically maintained, and the heat exchange efficiency between high temperature flue gas and heat storage body, combustion air and gas and heat storage body is improved.

[0017] (2) It solves the problems of existing regenerative burners having a large overall volume, unreasonable structure, low overall heat exchange efficiency, high manufacturing and maintenance costs, and a lot of useless heat storage bodies. The overall structure is compact and easy to maintain and repair.

[0018] (3) Through preliminary verification, the application of the dual regenerative combustion technology of the regenerative burner of this invention in a large vertical magnesium smelting reduction furnace can reduce the head of the induced draft fan of the magnesium smelting reduction furnace by about 10% and increase the reduction rate and combustion efficiency by about 3%. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the regenerative burner of the present invention; Figure 2 for Figure 1 The right view; Figure 3 This is a schematic diagram of the heat exchange unit in specific embodiment 1; Figure 4 This is a schematic diagram of the heat exchange unit in specific embodiment 2; Figure 5 This is one of the structural schematic diagrams of the magnesium smelting apparatus of the present invention; Figure 6 This is the second schematic diagram of the magnesium smelting apparatus of the present invention. Detailed Implementation

[0020] The present invention will now be further described with reference to the accompanying drawings. Specific Implementation

[0021] like Figure 1 , Figure 2 and Figure 3 As shown, a regenerative burner with variable cross-section to adjust Reynolds number includes a burner housing 2. The burner housing 2 is divided into a first receiving chamber 5 and a second receiving chamber 3 by an intermediate partition 4. Both the first receiving chamber 5 and the second receiving chamber 3 are equipped with heat exchange units. The heat exchange units are formed by an array of multiple heat storage bodies A4. Each heat storage body A4 has an array of evenly distributed through holes A3. The through holes A3 between the multiple heat storage bodies A4 are connected sequentially from the outside to the inside to form a gas channel. The cross-section of the gas channel increases sequentially from the outside to the inside.

[0022] An air inlet 6 connected to a gas passage is installed on the outside of the first chamber 5, and an air outlet 1 connected to a gas passage is installed on the inside of the first chamber 5. An air inlet 2 1 connected to a gas passage is installed on the outside of the second chamber 3, and an air outlet 2 connected to a gas passage is installed on the inside of the second chamber 3.

[0023] like Figure 3As shown, the heat exchange unit is divided into N heat storage unit groups from the outside to the inside: the first heat storage unit group, the second heat storage unit group, ..., the Nth heat storage unit group. The number of heat storage bodies A4 in these N heat storage unit groups increases sequentially. A buffer chamber A2 is provided between two adjacent heat storage unit groups. The buffer chamber A2 is used to connect the gas channels of the two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area.

[0024] An inlet buffer chamber A1 is provided at the outer end of the first heat storage unit group, and an outlet buffer chamber A5 is provided at the innermost end of the heat storage unit group. Both the inlet buffer chamber A1 and the outlet buffer chamber A5 are connected to the gas channel. The first air inlet 6 and the second air inlet 1 are respectively connected to the corresponding inlet buffer chamber A1, and the first air outlet and the second air outlet are respectively connected to the corresponding outlet buffer chamber A5. The first air outlet and the second air outlet converge at the main air outlet.

[0025] Meanwhile, a solid heat storage body is filled inside the burner housing 2. The solid heat storage body complements the shape of the heat exchange unit, filling the space inside the burner housing. This prevents the burner housing 2 from being too compact and also helps to dissipate the heat stored in the heat exchange unit. On the other hand, refractory mortar can also be filled inside the burner housing 2. The refractory mortar fills the gaps between the various heat storage bodies A4 to ensure the airtightness of the gas passage. This ensures that the flue gas, combustion air, and combustion gas flow along the gas passage without short-circuiting and skipping the return path to be discharged directly.

[0026] Figure 3 The diagram only illustrates the number of heat storage bodies A4. In actual use, there are no restrictions on the specific number of heat storage bodies A4 in each heat storage unit group or the number of heat storage unit groups. As long as the cross-section of the gas channel increases sequentially from the outside to the inside to meet a relatively stable Reynolds number (Re) and prevent the Reynolds number from falling to the laminar flow region (Re<2300), the optimal heat transfer coefficient can be obtained. The preferred method is a three-pass system. Specific Implementation

[0027] like Figure 4 As shown, another structural form of the heat exchange unit is as follows: it is divided into M heat storage unit groups from bottom to top, namely the first heat storage unit group, the second heat storage unit group, ..., the Mth heat storage unit group. The first heat storage unit group, the second heat storage unit group, ..., the Mth heat storage unit group have the same length from the outside to the inside. The number of heat storage bodies B2 in the M heat storage unit groups increases sequentially. The transition points of the M heat storage unit groups are connected sequentially through buffer chambers B4. The buffer chambers B4 are used to connect the gas channels of two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area that goes around from top to bottom.

[0028] An inlet buffer chamber B1 is provided at the outer end of the first regenerator unit group, and an outlet buffer chamber B5 is provided at the inner end of the Mth regenerator unit group. Both the inlet buffer chamber B11 and the outlet buffer chamber B5 are connected to the gas channel. The first gas inlet 1 and the second gas inlet 6 are respectively connected to the corresponding inlet buffer chamber B1, and the first gas outlet 1 and the second gas outlet 2 are respectively connected to the corresponding outlet buffer chamber B5. The first gas outlet 1 and the second gas outlet 2 converge at the total gas outlet located at the ignition point inside the magnesium reduction furnace.

[0029] Similarly, when air and gas flow into one of the burners, they absorb heat from the first heat storage unit group, the second heat storage unit group, ..., the Mth heat storage unit group in sequence to preheat them. During this process, the volume of air and gas expands while the cross-section of the gas channel increases accordingly, which controls the flow rate to remain basically unchanged, thereby ensuring a stable Reynolds number (Re) and ultimately obtaining the optimal heat transfer coefficient.

[0030] Figure 4 The diagram only shows the number of heat storage bodies B2. In actual use, there are no restrictions on the specific number of heat storage bodies B2 in each heat storage body unit group or the number of heat storage body unit groups. As long as the cross-section of the gas channel increases from the outside to the inside to meet a relatively stable Reynolds number (Re) and prevent the Reynolds number from falling to the laminar flow region (Re<2300), the optimal heat transfer coefficient can be obtained.

[0031] Compared with Specific Embodiment 1, the regenerative burner of this structure is more compact, with a moderate volume, low manufacturing and maintenance costs, and makes full use of each regenerative element. Through preliminary verification, the application of the regenerative burner of this invention with dual regenerative combustion technology in a large vertical magnesium smelting reduction furnace can reduce the induced draft fan head of the magnesium smelting reduction furnace by about 10% and increase the reduction rate and combustion efficiency by about 3%. Specific Implementation

[0032] like Figure 5 As shown, a magnesium smelting apparatus with a regenerative burner as described above includes a magnesium reduction furnace, a combustion air source, a gas source, a first four-way reversing valve, a first induced draft fan, a second four-way reversing valve, and a second induced draft fan. The combustion air source, the first four-way reversing valve, and the first induced draft fan are connected in sequence through a first pipeline, and the gas source, the second four-way reversing valve, and the second induced draft fan are connected in sequence through a second pipeline. Both the first induced draft fan and the second induced draft fan are connected to a chimney. Two regenerative burners are symmetrically installed on the left and right sides of the magnesium reduction furnace, referred to as the left burner and the right burner respectively. The first and second air inlets of the left burner are connected to the first and second four-way reversing valves through pipes, respectively. Similarly, the first and second air inlets of the right burner are connected to the first and second four-way reversing valves through pipes, respectively.

[0033] When the left burner receives combustion air and gas, and the right burner receives flue gas, the combustion air source delivers combustion air through a pipeline and through the first four-way reversing valve into the first air inlet of the left burner, and the gas source delivers gas through a pipeline and through the second four-way reversing valve into the second air inlet of the left burner. After being preheated by the left burner, the gas is mixed and then enters the magnesium reduction furnace. The flue gas in the magnesium reduction furnace transfers heat to the right burner when it passes through the right burner, and then enters the chimney after passing through the first and second inlet ports of the right burner and the first and second four-way reversing valves respectively. like Figure 6 As shown, when the right burner receives combustion air and fuel gas and the left burner outputs flue gas, and vice versa, the above process is repeated alternately. Figure 5 and Figure 6 The action.

[0034] Throughout the process, when the high-temperature flue gas flows out of the magnesium reduction furnace, it transfers heat to the heat storage body A4 of the left or right burner. When the combustion air and fuel gas flow through the left or right burner, they absorb the heat from the heat storage body A4 to preheat it. This process is repeated alternately.

[0035] In this process, whether the flue gas flows out of the furnace through the burner and transfers heat to the heat storage body of the burner for heat storage, resulting in the shrinkage of the flue gas volume and a decrease in flow velocity, or the combustion air and fuel gas flow into the magnesium reduction furnace through the burner and the heat storage body transfers the stored heat to the combustion air and fuel gas for preheating, resulting in the expansion of the combustion air and fuel gas volume and an increase in flow velocity, all these processes are basically maintained by the special improvement of the variable cross-section of the burner gas channel in this invention. This improves the heat exchange efficiency between the high-temperature flue gas and the heat storage body, and between the combustion air and fuel gas and the heat storage body.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A regenerative burner with variable cross-section to adjust the Reynolds number, characterized in that, The device includes a burner housing, which is divided into a first chamber and a second chamber by a partition. Both chambers are equipped with heat exchange units, which are composed of multiple heat storage elements arranged in an array. Each heat storage element has an array of evenly distributed through holes. The through holes between the multiple heat storage elements are connected sequentially from the outside to the inside to form a gas channel. The cross-section of the gas channel increases sequentially from the outside to the inside.

2. The regenerative burner with variable cross-section to adjust Reynolds number according to claim 1, characterized in that, An air inlet end 1 connected to a gas passage is installed on the outside of the first receiving chamber, and an air outlet end 1 connected to a gas passage is installed on the inside of the first receiving chamber. An air inlet end 2 connected to a gas passage is installed on the outside of the second receiving chamber, and an air outlet end 2 connected to a gas passage is installed on the inside of the second receiving chamber.

3. The regenerative burner with variable cross-section to adjust Reynolds number according to claim 1, characterized in that, The heat exchange unit is divided into N heat storage unit groups from the outside to the inside: the first heat storage unit group, the second heat storage unit group, ..., the Nth heat storage unit group. The number of heat storage elements in the N heat storage unit groups increases sequentially. A buffer chamber is provided between two adjacent heat storage unit groups. The buffer chamber is used to connect the gas channels of the two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area.

4. The regenerative burner with variable cross-section to adjust Reynolds number according to claim 1, characterized in that, The heat exchange unit is divided into M heat storage unit groups from bottom to top: the first heat storage unit group, the second heat storage unit group, ..., the Mth heat storage unit group. The number of heat storage elements in each of the M heat storage unit groups increases sequentially. The transition points of the M heat storage unit groups are connected sequentially by buffer chambers. The buffer chambers are used to connect the gas channels of two adjacent heat storage unit groups, thereby forming a gas channel with a gradually increasing cross-sectional area that winds upwards.

5. The regenerative burner with variable cross-section for adjusting Reynolds number according to any one of claims 1 to 4, characterized in that, An inlet buffer chamber is provided at the outer end of the first heat storage unit group, and an outlet buffer chamber is provided at the innermost end of the innermost heat storage unit group. Both the inlet buffer chamber and the outlet buffer chamber are connected to the gas channel. The first air inlet and the second air inlet are respectively connected to the corresponding inlet buffer chambers, and the first air outlet and the second air outlet are respectively connected to the corresponding outlet buffer chambers. The first air outlet and the second air outlet converge at the main air outlet.

6. The regenerative burner with variable cross-section to adjust Reynolds number according to claim 3, characterized in that, The burner housing is filled with a solid heat storage body, the shape of which complements that of the heat exchange unit, thus filling the space inside the burner housing.

7. The regenerative burner with variable cross-section to adjust Reynolds number according to claim 3 or 4, characterized in that, The burner chamber is filled with refractory mortar, which fills the gaps between the various heat storage elements to ensure the airtightness of the gas passage.

8. A magnesium smelting apparatus having a regenerative burner as described in claims 1 to 7, characterized in that, It includes a magnesium reduction furnace, a combustion air source, a gas source, a first four-way reversing valve, a first induced draft fan, a second four-way reversing valve, and a second induced draft fan. The combustion air source, the first four-way reversing valve, and the first induced draft fan are connected in sequence through a first pipeline. The gas source, the second four-way reversing valve, and the second induced draft fan are connected in sequence through a second pipeline. Both the first induced draft fan and the second induced draft fan are connected to a chimney. Two or more sets of regenerative burners are symmetrically installed on the left and right sides of the magnesium reduction furnace, referred to as the left burner and the right burner, respectively. The first and second air inlets of the left burner are connected to the first and second four-way reversing valves through pipes, respectively. Similarly, the first and second air inlets of the right burner are connected to the first and second four-way reversing valves through pipes, respectively.

9. The magnesium smelting apparatus according to claim 8, characterized in that, When the left burner receives combustion air and gas, and the right burner receives flue gas, the combustion air source delivers combustion air through a pipeline and through the first four-way reversing valve into the first air inlet of the left burner, and the gas source delivers gas through a pipeline and through the second four-way reversing valve into the second air inlet of the left burner. After being preheated by the left burner, the gas is mixed and then enters the magnesium reduction furnace. The flue gas in the magnesium reduction furnace transfers heat to the right burner when it passes through the right burner, and then enters the chimney after passing through the first and second inlet ports of the right burner and the first and second four-way reversing valves respectively. When the right burner receives combustion air and gas, the left burner will emit flue gas, and vice versa, and the above actions will be repeated alternately.

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