Method and preheating device for preheating scrap steel without flame contact

Abstract

The present application relates to a kind of preheating scrap steel without flame contact method and preheating device, belong to steel metallurgical smelting technical field to solve the problems of low combustible gas utilization rate and scrap steel preheating temperature unevenness.The preheating device includes flue gas generator, flue gas pipeline and ladle;The flue gas generator includes combustion chamber, with the combustible gas pipeline and combustion-supporting gas pipeline being communicated with the combustion chamber;The flue gas pipeline includes sequentially communicated inlet pipe, ring pipe and outlet pipe;The inlet pipe is communicated with the combustion chamber, the ring pipe is located at the outer circumferential surface of the ladle, and the outlet pipe penetrates the sidewall of the bottom of the ladle and is communicated with the inner cavity of the ladle.The temperature of the scrap steel in the bottom layer and upper layer of the ladle after preheating is uniform, the temperature difference is smaller, the temperature difference is below 100 DEG C, and the utilization rate of combustible gas is above 50%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy smelting, and particularly relates to a method for preheating scrap steel without flame contact and a preheating device. BACKGROUND

[0002] Although electric furnace smelting has certain advantages in carbon emission compared with long process, the product price under the condition of full scrap steel electric furnace smelting is obviously higher than the converter smelting cost. The high scrap steel ratio converter production process can improve economic benefits, so many enterprises use various methods to improve the scrap steel ratio in the converter long process production process. The scrap steel ratio can obviously reduce the carbon emission per ton of steel, thereby reducing the coke consumption of the steel enterprise.

[0003] The scrap steel preheating technology is an important method for improving the scrap steel ratio of the converter process, and is widely used in the industry. In the production process of deformed steel, many enterprises and researchers have done a lot of work in scrap steel preheating. At present, the scrap steel preheating basically uses coal gas combustion to directly bake and preheat the scrap steel, and only the position of the scrap steel preheating, the burner and the combustion mode are different. The heat utilization rate is low in the actual production process. Practical experience shows that the coal gas utilization rate of this type of preheating method is relatively low, generally only 10-20%, the temperature difference between the upper layer scrap steel and the lower layer scrap steel is large, the temperature difference can reach more than 600 DEG C, the baking efficiency is low, so the baking raw material requirement is high. Secondly, in an open environment, the scrap steel is directly preheated by using open flame, the oxygen is excessive, the scrap steel is seriously oxidized, and the iron loss is high. Finally, this type of scrap steel preheating method generally does not set a special flue gas treatment device, so it causes certain environmental pollution problems.

[0004] Therefore, it is urgent to develop a scrap steel preheating method and device to solve the problems of low combustible gas utilization rate, unorganized emission of flue gas in the preheating process and uneven preheating temperature of scrap steel. It is very important to develop a closed, environmentally friendly, high energy utilization efficiency and uniform preheating method. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a method for preheating scrap steel without flame contact and a preheating device to solve the problems of low combustible gas utilization rate and uneven preheating temperature of scrap steel.

[0006] In one aspect, the present application provides a preheating device for preheating scrap steel without flame contact, comprising a flue gas generator, a flue gas pipeline and a ladle.

[0007] The flue gas generator comprises a combustion chamber, a combustible gas pipeline and a combustion-supporting gas pipeline which are in communication with the combustion chamber.

[0008] The flue gas pipeline comprises a gas inlet pipe, a ring pipe and a gas outlet pipe which are sequentially communicated; the gas inlet pipe is communicated with the combustion chamber; the ring pipe is located on the outer circumferential surface of the ladle; and the gas outlet pipe penetrates the side wall of the bottom of the ladle and is communicated with the inner cavity of the ladle.

[0009] Further, the ladle is a U-shaped structure with an open upper end, and a dust removal cover is arranged at the opening of the ladle.

[0010] Further, the flue gas pipeline comprises a plurality of gas outlet pipes which are uniformly arranged around the outer circumferential surface of the ladle.

[0011] Further, the gas inlet pipe is arranged in a non-coaxial manner with the gas outlet pipe.

[0012] Further, a refractory material is arranged on the inner wall of the ladle.

[0013] Further, a support disc is arranged in the inner cavity of the ladle, the support disc is a hollow circular structure, a through hole is arranged on the side wall of the support disc and communicated with the gas outlet pipe, and a plurality of smoke conveying channels are arranged on the upper surface of the support disc and uniformly arranged around the center of the support disc.

[0014] Further, a plurality of columns are fixedly connected to the upper surface of the support disc, the columns are hollow and communicated with the smoke conveying channels; the end of the column away from the smoke conveying channel is closed, and a plurality of through holes are arranged on the side wall of the column.

[0015] On the other hand, the present application provides a method for preheating scrap steel without flame contact, which is realized by the preheating device of the present application and comprises the following steps:

[0016] The scrap steel is loaded into the ladle, combustible gas and combustion-supporting gas are introduced into the combustion chamber, and hot flue gas is generated after combustion in the combustion chamber; the hot flue gas enters the ladle through the gas inlet pipe, the ring pipe and the gas outlet pipe, and the scrap steel in the ladle is preheated.

[0017] Further, the utilization rate of the combustible gas is above 50%.

[0018] Further, the temperature difference between the upper layer of scrap steel and the bottom layer of scrap steel in the ladle is below 100 DEG C.

[0019] Compared with the prior art, the present application can at least realize one of the following beneficial effects:

[0020] 1. The application provides a kind of scrap preheating device, including flue gas generator, flue gas pipeline and ladle, flue gas generator and ladle are communicated by flue gas pipeline;Wherein flue gas generator includes combustion chamber, hot flue gas is generated in combustion chamber, hot flue gas enters the bottom of ladle along flue gas pipeline and preheats scrap, hot flue gas is transmitted upwards through the gap between scrap, and preheats the scrap of upper layer of ladle.Using the preheating device of the application, open fire does not directly contact with scrap, can reduce the oxidation rate of scrap, also can improve the utilization rate of combustible gas, so that utilization rate is more than 50%, and the temperature of bottom layer and upper layer of ladle is uniform, temperature difference is smaller, and temperature difference is below 100 DEG C.

[0021] 2, the preheating device provided by the application is provided with refractory material on the inner wall of the ladle and dust cover on the upper end of the ladle, forming a closed environment, prolonging the residence time of hot flue gas in the ladle, reducing heat exchange with the outside of the ladle, improving the utilization rate of hot flue gas, shortening the preheating time, improving production efficiency and reducing cost.

[0022] 3, the preheating device provided by the application further includes a support disc arranged in the ladle, and the support disc is a hollow circular structure, the side wall of the support disc is provided with a through hole communicated with the gas outlet pipe, and a plurality of smoke conveying channels are arranged on the upper surface of the support disc, and the smoke conveying channels are uniformly arranged around the center of the support disc.Using the above support disc structure, hot flue gas is more evenly distributed, and uniformly rises from the bottom of the ladle, continuously heats the scrap in the ladle, further improves the utilization rate of hot flue gas, and makes the temperature of scrap uniform.

[0023] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the application. The purpose and other advantages of the application can be realized and obtained through the contents specifically indicated in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are for the purpose of illustrating preferred embodiments of the application only, and are not to be construed as limiting the application thereto, wherein the same reference numerals in the several embodiments denote the same or similar components.

[0025] Figure 1 It is a top view of scrap preheating device;

[0026] Figure 2 It is a top view of scrap preheating device; Figure 1 It is a sectional view of scrap preheating device;

[0027] Figure 3 It is a schematic view of scrap preheating device;

[0028] Figure 4 Fig. 1 is a schematic view of a support disc for a scrap steel preheating device;

[0029] Figure 5 Fig. 2 is a sectional view of the support disc;

[0030] Figure 6 Fig. 3 is a schematic view of the support disc with a stand;

[0031] In the figure, 1 is a combustible gas pipeline; 2 is a combustion-supporting gas pipeline; 3 is a combustion chamber; 4 is an air inlet pipe; 5 is a ring pipe; 6 is an air outlet pipe; 7 is refractory material; 8 is a ladle; 9 is scrap steel; 10 is a dust hood; 11 is a connecting pipe; 12 is a smoke conveying passage; 13 is a stand; and 14 is a fan. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the implementation examples of the present application, illustrate the principles of the present application, but are not intended to limit the scope of the present application.

[0033] In steel smelting, preheating of scrap steel can increase the scrap steel ratio, and can significantly reduce the carbon emission per ton of steel, thereby reducing the coke consumption of a steel enterprise. At present, the preheating of scrap steel mainly adopts coal gas combustion to directly bake and preheat the scrap steel. During preheating, the oxidation of the scrap steel is relatively serious, and the heat loss is relatively fast, resulting in a relatively low utilization rate of coal gas. It is also found in the production practice that, when the scrap steel is preheated by using coal gas combustion, it is found through detection that the temperature difference between the bottom layer and the upper layer of the scrap steel in the ladle is relatively large, and the temperature cannot be made relatively uniform.

[0034] Reference Figure 1 and Figure 2 The present application provides a preheating device for preheating scrap steel without flame contact, which comprises a smoke generator, a smoke pipeline and a ladle 8.

[0035] The smoke generator comprises a combustion chamber 3, a combustible gas pipeline 1 and a combustion-supporting gas pipeline 2 which are in communication with the combustion chamber 3.

[0036] The smoke pipeline comprises an air inlet pipe 4, a ring pipe 5 and an air outlet pipe 6 which are in communication in sequence; the air inlet pipe 4 is in communication with the combustion chamber 3, the ring pipe 5 is located on the outer circumferential surface of the ladle 8, and the air outlet pipe 6 penetrates through the side wall of the bottom of the ladle 8 and is in communication with the inner cavity of the ladle 8.

[0037] Compared with the prior art, the preheating device provided by the application does not directly contact the waste steel 9 with the open fire, but uses the hot flue gas generated after the combustion of the combustible gas to preheat the waste steel 9. The hot flue gas generated in the combustion chamber 3 preheats the waste steel 9 from the bottom of the ladle 8 along the flue gas pipeline, and the hot flue gas continuously passes through the waste steel 9 and exchanges heat with the waste steel 9. By using the preheating device of the application to preheat the waste steel 9, the oxidation rate of the waste steel 9 can be reduced, the utilization rate of the combustible gas can be improved, the utilization rate is more than 50%, and the temperature of the waste steel 9 in the bottom layer and the upper layer of the ladle 8 is uniform, and the temperature difference is small, and the temperature difference is less than 100 DEG C.

[0038] Specifically, the ladle 8 is a U-shaped structure with an open upper end, and a dust removal cover 10 is arranged at the opening of the ladle 8.

[0039] The ladle 8 is a U-shaped structure surrounded by a steel plate, and the upper end of the ladle 8 is designed as an opening for conveniently placing the waste steel 9, and the dust removal cover 10 is arranged at the upper end of the ladle 8. The dust removal cover 10 forms a closed environment with the ladle 8, so that the hot flue gas circulates in the ladle 8 to sufficiently preheat the waste steel 9 in the ladle 8, and the temperature of the waste steel 9 is uniform. In addition, the connecting pipe 11 is arranged on the dust removal cover 10, and the connecting pipe 11 is connected with the dust removal system to remove the dust and other impurities generated in the preheating process, thereby reducing the pollution to the environment.

[0040] Specifically, the flue gas pipeline includes a plurality of gas outlet pipes 6, and the plurality of gas outlet pipes 6 are uniformly arranged around the outer periphery of the ladle 8.

[0041] In the preheating device of the application, the ring pipe 5 is located on the outer periphery of the ladle 8 and does not directly contact the ladle 8, but is connected with the ladle 8 through the plurality of gas outlet pipes 6, and the plurality of gas outlet pipes 6 are uniformly arranged around the outer periphery of the ladle 8. After the hot flue gas is generated in the combustion chamber 3, it enters the ring pipe 5 from the gas outlet pipe 6, fills the ring pipe 5, and then enters the ladle 8 from the gas outlet pipe 6. The ring pipe 5 and the gas outlet pipe 6 uniformly inject the hot flue gas into the ladle 8, so that the temperature of the waste steel 9 in the ladle 8 is uniform, thereby improving the utilization rate of the combustible gas, shortening the heating time, and improving the production efficiency.

[0042] Preferably, the number of the gas outlet pipes 6 is 3-6.

[0043] Preferably, the gas outlet pipes 6 are fixed below the ring pipe 5.

[0044] The gas outlet pipe 6 is communicated with the ring pipe 5 and is arranged below the ring pipe 5. Since the hot flue gas has a small density and floats above the ring pipe 5, the hot flue gas flows into the ladle 8 from the gas outlet pipe 6 only after the ring pipe 5 is completely filled, so that the amount of hot flue gas in each gas outlet pipe 6 is relatively uniform. The number of the gas outlet pipes 6 can be increased or decreased according to the size of the ladle 8 and actual production requirements.

[0045] Specifically, the gas inlet pipe 4 is arranged coaxially with the gas outlet pipe 6.

[0046] In the present application, the hot flue gas flows through the gas inlet pipe 4, the ring pipe 5 and the gas outlet pipe 6, and finally enters the ladle 8. Under the action of the ring pipe 5, the hot flue gas is uniformly distributed before entering the ladle 8. If the gas inlet pipe 4 and the gas outlet pipe 6 are coaxially arranged, most of the hot flue gas directly enters the ladle 8 through the gas inlet pipe 4 and the gas outlet pipe 6, which can cause the overall temperature of the scrap steel 9 to be uneven, and in order to reach the preheating temperature, the preheating time must be prolonged, thereby reducing the utilization rate of the combustible gas. Therefore, in the present application, the gas inlet pipe 4 and the gas outlet pipe 6 are arranged non-coaxially.

[0047] Specifically, the inner wall of the ladle 8 is lined with the refractory material 7.

[0048] Preferably, the thickness of the refractory material 7 is 120-180mm.

[0049] Preferably, the refractory material 7 can be clay brick or high alumina brick.

[0050] A layer of refractory material 7 is arranged on the inner wall of the ladle 8, which can be clay brick or high alumina brick. The refractory material 7 can insulate the scrap steel 9 in the ladle 8, reduce the heat loss in the ladle 8, further improve the utilization rate of the combustible gas, reduce the amount of combustible gas and reduce the cost. The thickness of the refractory material 7 is in the range of 120-180mm. When the thickness of the refractory material 7 is less than 120mm, the heat loss in the ladle 8 is relatively large, and the insulation effect is poor. When the thickness of the refractory material 7 is greater than 180mm, the insulation effect does not improve with the increase of the thickness, and the over-thick refractory material 7 can cause waste of materials.

[0051] Specifically, a layer of asbestos or rock wool with a thickness of 10-30mm can be placed between the ladle 8 and the refractory material 7.

[0052] Referring to Figure 3 and Figure 4 Specifically, a support disc is arranged in the ladle 8. The support disc is a hollow circular structure. A through hole is arranged in the side wall of the support disc and is communicated with the gas outlet pipe 6. A plurality of smoke conveying channels 12 are arranged on the upper surface of the support disc and are uniformly arranged around the center of the support disc.

[0053] In the present application, the gas outlet pipe 6 is fixed to the side wall of the bottom of the ladle 8 and extends into the ladle 8, and the hot flue gas is gathered along the inner wall of the ladle 8 to the center, thereby preheating the scrap steel 9. Further, a support disc is placed in the interior of the ladle 8, so that the hot flue gas uniformly rises from the bottom of the ladle 8, thereby improving the uniformity of the overall temperature of the scrap steel 9.

[0054] Specifically, the diameter of the smoke conveying channel 12 is 30-100mm.

[0055] The support disc is a hollow circular structure, and the diameter of the support disc is matched with the diameter of the interior of the ladle 8. A plurality of through holes are formed in the side wall of the support disc, which are matched with the gas outlet pipe 6, so as to facilitate the hot flue gas to enter the interior of the support disc. A plurality of smoke conveying channels 12 are formed in the upper surface of the support disc and are uniformly arranged around the center thereof, so that the hot flue gas entering the ladle 8 is more uniform, thereby improving the utilization rate of the hot flue gas.

[0056] Preferably, the cross-section of the smoke conveying channel 12 is trapezoidal, and the small-up-big-down arrangement of the smoke conveying channel 12 can increase the jet distance of the hot flue gas, which can be applied to the ladle 8 with higher scrap steel 9, so as to ensure that the temperature of the bottom layer and the upper layer of the scrap steel 9 in the ladle 8 is uniform, and the temperature difference is small.

[0057] Referring to Figure 5 Preferably, the support disc is composed of a disc and a ring disc. The disc and the ring disc are concentrically arranged, and the ring disc is located outside the disc.

[0058] In order to prevent the scrap steel 9 and the slag from blocking the smoke conveying channel 12 on the support disc, a screen is placed between the support disc and the scrap steel 9, so that the hot flue gas smoothly enters the ladle 8 from the interior of the support disc and preheats the scrap steel 9.

[0059] Referring to Figure 6 Specifically, a plurality of columns 13 are fixed to the upper surface of the support disc, the columns 13 are hollow and communicate with the smoke conveying channels 12, one end of the column 13 away from the smoke conveying channel 12 is closed, and a plurality of through holes are formed in the side wall of the column 13.

[0060] In order to prevent the scrap steel 9 or the slag from blocking the smoke conveying channel 12 and to ensure that the hot flue gas more uniformly enters the ladle 8, a hollow column 13 is fixed above the smoke conveying channel 12, and a plurality of through holes are uniformly formed in the side wall of the column 13. The hot flue gas passes through the interior of the support disc, then passes through the smoke conveying channel 12, and then is sprayed out from the through holes in the side wall of the column 13. The hot flue gas is distributed in a circular shape around the center line of the column 13, and is more uniformly distributed in the ladle 8, which can further improve the utilization rate of the combustible gas and ensure that the temperature in the ladle 8 is more uniform.

[0061] Specifically, the column 13 extends away from the support plate to the middle upper part of the ladle 8, and a plurality of through holes are uniformly arranged on the side wall of the column 13, and the column 13 is detachably connected with the support plate.

[0062] Specifically, a plurality of flue gas circulating devices are arranged on the dust hood 10, and the flue gas circulating devices are located at the top of the dust hood 10.

[0063] Specifically, the flue gas circulating device comprises a horn-shaped gas collecting hood, a fan 14 and a pipeline, the horn-shaped gas collecting hood is open to the side of the ladle 8, the fan 14 is located away from the side of the ladle 8, and one end of the pipeline is connected to the fan 14, and the other end of the pipeline penetrates through the side wall of the middle upper part of the ladle 8 and communicates with the inner cavity of the ladle 8.

[0064] Specific application process: hot flue gas is generated in the combustion chamber 3, enters the ladle 8 through the inlet pipe 4, the ring pipe 5 and the outlet pipe 6 to preheat the scrap steel 9, at this time the fan 14 in the flue gas circulating device is in a closed state, and the heat of the hot flue gas in the upper layer of the ladle 8 is reduced and directly enters the dust removal system through the connecting pipe 11. After preheating for 10-15 minutes, the temperature of the hot flue gas in the upper layer of the ladle 8 gradually rises, the fan 14 is started, and the hot flue gas enters the pipeline again along the pipeline to preheat the scrap steel 9 in the middle and upper parts, so that the hot flue gas is recycled; when the scrap steel 9 in the middle reaches the predetermined temperature, the fan 14 is closed, and the hot flue gas enters the dust removal system through the connecting pipe 11.

[0065] The present application provides a method for preheating scrap steel 9 without flame contact, the scrap steel 9 is loaded into the ladle 8, combustible gas and combustion-supporting gas are introduced into the combustion chamber 3, and hot flue gas is generated after combustion in the combustion chamber 3, the hot flue gas enters the ladle 8 through the inlet pipe 4, the ring pipe 5 and the outlet pipe 6 to preheat the scrap steel 9 in the ladle 8. After preheating, the temperature difference between the upper layer scrap steel 9 and the bottom layer scrap steel 9 in the ladle 8 is below 50℃, and the utilization rate of the combustible gas is above 40% after calculation.

[0066] In the present application, the combustible gas can be blast furnace gas or coke oven gas, which can be selected according to the enterprise's own conditions. The combustible gas is preferably blast furnace gas. The combustion-supporting gas can be air or oxygen, and is preferably oxygen.

[0067] The flow rate of the combustible gas is 3-10 m / s. The flow rate of the combustion-supporting gas is 3-10 m / s.

[0068] In order to more clearly describe the present application, the following examples and comparative examples are further illustrated

[0069] The following examples and comparative examples preheat 8t of scrap steel at a time, and the space of the scrap steel preheating chamber is 10m 3The scrap steel is preheated from room temperature to 800 DEG C.

[0070] Embodiment 1

[0071] With reference to Figure 1 and Figure 2 The present application provides a preheating device for scrap steel, which comprises a combustible gas pipeline, a combustion-supporting gas pipeline, a combustion chamber, an air inlet pipe, a ring pipe, an air outlet pipe, a refractory material, a ladle and a dust removal cover.

[0072] The combustible gas pipeline and the combustion-supporting gas pipeline are connected to the combustion chamber, one end of the air inlet pipe is also connected to the combustion chamber and the air inlet pipe is located on the side of the combustion chamber away from the combustible gas pipeline and the combustion-supporting gas pipeline; the other end of the air inlet pipe is connected to the ring pipe, the ring pipe is circular and surrounds the outer circumferential surface of the ladle without contacting the ladle; the ring pipe and the ladle are connected through the air outlet pipe, four air outlet pipes are evenly distributed around the central axis of the ladle, one end of each air outlet pipe is connected to the lower part of the ring pipe and the other end of each air outlet pipe is connected to the bottom of the ladle and extends into the interior of the ladle; a 150mm-thick high-alumina-brick refractory material is laid in the interior of the ladle, a dust removal cover is arranged above the ladle and the dust removal cover is connected to a dust removal system through a connecting pipe.

[0073] After the preheating device is connected, the scrap steel is loaded into the ladle, the dust removal cover is placed above the ladle, combustible gas and combustion-supporting gas are introduced into the combustion chamber, the combustible gas is blast furnace gas with a flow rate of 5±0.5m / s and the combustion-supporting gas is air with a flow rate of 5±0.5m / s; hot flue gas is generated after combustion in the combustion chamber, the hot flue gas enters the ladle from the bottom of the ladle through the air inlet pipe, the ring pipe and the air outlet pipe and preheats the scrap steel in the ladle.

[0074] Embodiment 2

[0075] Embodiment 2 is basically the same as Embodiment 1, except that a support disc is arranged in the interior of the ladle in Embodiment 2.

[0076] With reference to Figure 3 The support disc is cylindrical and hollow, the support disc is arranged at the bottom of the ladle and the outer diameter of the support disc is equal to or slightly smaller than the inner diameter of the ladle. Five smoke conveying channels are arranged on the upper surface of the support disc and the diameter of each smoke conveying channel is 50mm, and through holes are arranged on the side wall of the support disc for inserting the air outlet pipes, the number of the through holes is equal to the number of the air outlet pipes.

[0077] Embodiment 3

[0078] Embodiment 3 is basically the same as Embodiment 2, except that a column is fixedly connected to the upper surface of the support disc in Embodiment 3.

[0079] With reference to Figure 4A stand is arranged above the smoke conveying passage, the stand is a hollow cylinder, the lower end of the stand is communicated with the smoke conveying passage, and six through holes are arranged on the sidewall of the stand and are uniformly distributed around the central axis of the stand.

[0080] Comparative Example 1

[0081] In the comparative example, the waste steel in the ladle is heated by direct injection of coal gas. The waste steel is added to the ladle, and the coal gas and combustion-supporting gas are directly burned on the upper part of the waste steel to heat the waste steel, and the waste steel at the lower part of the ladle is preheated by heat conduction.

[0082] Performance detection

[0083] The heating time of the above-mentioned examples 1-3 and comparative example 1 is recorded, the thermocouple is embedded in the middle of the ladle to measure the temperature, when the waste steel in the middle of the ladle reaches 800℃, the delivery of the combustible gas and the combustion-supporting gas is stopped, the heating time from the beginning to the end is recorded, and the temperature of the waste steel at the upper part and the bottom of the ladle is measured to calculate the temperature difference. The detection results are shown in Table 1.

[0084] The utilization rate of the combustible gas is calculated by formula (1).

[0085]

[0086] Wherein the heat absorbed by the waste steel = the weight of the waste steel x the temperature difference x the specific heat capacity of the waste steel;

[0087] The temperature difference is the difference between the initial temperature and the final temperature; the specific heat capacity of the waste steel is 0.46 kJ / (kg·℃);

[0088] Wherein the heat generated by the combustible gas is the total amount of combustible gas consumption x the calorific value.

[0089] Table 1 detection results

[0090]

[0091] It can be seen from the combination of examples 1-3 and comparative example 1 and Table 1 that the waste steel in the ladle is preheated by the preheating device and the preheating method provided by the present application, the preheating time is relatively short, the temperature difference between the upper and lower waste steel in the ladle is small, and the utilization rate of the combustible gas is more than 50%.

[0092] In the comparative example 1, the traditional direct injection of coal gas preheating, the combustible gas has limited flame impact depth during combustion, and the high-temperature flue gas generated after combustion is easy to diffuse upward, so the temperature difference between the upper and lower waste steel after preheating is large, the utilization rate of the combustible gas is low, and the waste steel directly contacted with the flame is easy to be oxidized.

[0093] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A preheating device for preheating scrap steel by flameless contact, characterized by The device comprises a flue gas generator, a flue gas pipeline and a ladle; The flue gas generator comprises a combustion chamber, a combustible gas pipeline and a combustion-supporting gas pipeline connected with the combustion chamber; The flue gas pipeline comprises a gas inlet pipe, a ring pipe and a gas outlet pipe connected in sequence; the gas inlet pipe is connected with the combustion chamber, the ring pipe is located on the outer circumferential surface of the ladle, and the gas outlet pipe penetrates through the side wall of the bottom of the ladle and is connected with the inner cavity of the ladle; The ladle is of U-shaped structure with an open upper end, a dust removal cover is arranged at the opening of the ladle, a refractory material is arranged on the inner wall of the ladle, the thickness of the refractory material is 120-180 mm, and a layer of asbestos or rock wool with a thickness of 10-30 mm is arranged between the ladle and the refractory material; A support disc is arranged in the ladle, the support disc is of hollow circular structure, a through hole is formed in the side wall of the support disc and connected with the gas outlet pipe, a plurality of smoke conveying channels are formed in the upper surface of the support disc and evenly arranged around the center of the support disc, a plurality of columns are fixedly connected to the upper surface of the support disc, the columns are hollow and connected with the smoke conveying channels, the end of the column away from the smoke conveying channel is closed, a plurality of through holes are formed in the side wall of the column, and the cross section of the smoke conveying channel is trapezoidal. The temperature difference between the upper layer of scrap steel and the bottom layer of scrap steel in the ladle is below 100℃, and the preheating temperature is 800℃.

2. The preheating device for preheating scrap without flame contact according to claim 1, characterized in that, The flue gas pipeline comprises a plurality of gas outlet pipes, and the plurality of gas outlet pipes are evenly arranged around the outer circumferential surface of the ladle.

3. The preheating device for preheating scrap without flame contact according to claim 1, wherein The gas inlet pipe and the gas outlet pipe are arranged in different axes.

4. A method of preheating scrap steel without flame contact, characterized in that The preheating device is achieved by the steps of, The scrap steel is loaded into the ladle, combustible gas and combustion-supporting gas are introduced into the combustion chamber, hot flue gas is generated after combustion in the combustion chamber, the hot flue gas enters the ladle through the gas inlet pipe, the ring pipe and the gas outlet pipe, and the scrap steel in the ladle is preheated.

5. The method of preheating scrap steel by non-flame contact according to claim 4, wherein The utilization rate of the combustible gas is above 50%.

6. The method of preheating scrap steel by non-flame contact according to claim 4, wherein After preheating, the temperature difference between the upper layer of scrap steel and the bottom layer of scrap steel in the ladle is below 100℃.

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