A method for enhancing heat transfer by co-pyrolysis of high-temperature smelting slag and biomass

Abstract

The present invention discloses a method for enhancing heat transfer of high-temperature smelting slag and biomass co-pyrolysis, and belongs to the technical field of comprehensive resource utilization. The present invention comprises controlling the feeding speed, adding biomass material and high-temperature smelting slag into a rotary reactor cylinder, and arranging an evenly distributed lifting plate on the inner wall of the rotary reactor, wherein the evenly distributed lifting plates are 3-8 pieces and are evenly distributed along the circumference of the rotary reactor. The present invention optimizes the internal structure of the rotary reactor cylinder specifically, so that the high-temperature smelting slag and biomass particles have a higher heat transfer efficiency in the rotary reactor, thereby improving the reaction efficiency and reducing the reaction cost.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive resource utilization and relates to a method for enhancing heat transfer by co-pyrolysis of high-temperature smelting slag and biomass. Background Art

[0002] Various kilns in industrial production (such as rotary kilns, heating furnaces, converters, reverberatory furnaces, and fluidized bed roasters) usually have low thermal efficiency, only about 30%, while the heat taken away by high-temperature flue gas, high-temperature slag, and high-temperature products reaches 40% to 60%, of which the available waste heat accounts for about one-third of the fuel consumption. The available waste heat in the machinery, glass, papermaking and other industries accounts for more than 15%.

[0003] Taking the solid waste treatment industry as an example, rotary heating furnaces (or rotary kilns) are widely used in waste incineration, resource recovery and treatment. However, the thermal efficiency of traditional rotary heating furnaces is also low, resulting in energy waste and increased treatment costs. Especially in the field of comprehensive resource utilization, the original intention of using waste to treat waste is to reduce costs and improve resource utilization, but in actual application, it is often necessary to pay a high cost to achieve secondary utilization of resources, which is somewhat contrary to the original intention of using waste to treat waste.

[0004] High-temperature smelting slag itself has high problems. It can heat biomass materials to react to obtain smelting slag, biochar and high-temperature gaseous products. After physical separation of high-temperature gaseous products, smelting slag and biochar, bio-oil, biochar, gas products and secondary slag can be obtained. Among them, bio-oil can be used as fuel in the smelting industry, biochar can be used as activated carbon, soil conditioner, fuel, etc., gas products can be used as fuel gas, and can also be used to produce synthesis gas, hydrogen, etc. Secondary slag can be used as cement raw material, and high-temperature smelting slag and biomass themselves are wastes. Therefore, co-pyrolysis of high-temperature smelting slag and biomass is an important way to treat waste with waste.

[0005] Therefore, it is necessary to provide a method for enhancing heat transfer of co-pyrolysis of high-temperature smelting slag and biomass to improve the heat transfer efficiency of high-temperature smelting slag and biomass during the pyrolysis process, so as to achieve the purpose of more fully utilizing the waste heat of high-temperature smelting slag to treat biomass materials, reduce processing time, improve processing efficiency, and thus reduce operating costs, which is beneficial to actual production applications and truly realizes waste treatment and turning waste into treasure. Summary of the invention

[0006] In order to overcome the problems in the background technology, the present invention designs the internal structure of the rotary reactor to improve the heat transfer efficiency between high-temperature smelting slag and biomass during thermal decomposition, thereby improving the utilization rate of waste heat from high-temperature smelting slag, improving reaction efficiency and reducing costs.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] The heat transfer enhancement method includes controlling the feed rate, adding biomass materials and high-temperature smelting slag into a rotary reactor cylinder 1, and arranging evenly distributed lifting plates 2 on the inner wall of the rotary reactor. The evenly distributed lifting plates 2 are 3-8 and evenly distributed along the circumference of the rotary reactor.

[0009] Preferably, the rotary reactor is further provided with an equidistant spiral plate 3, which is fixedly connected to the inner wall of the rotary reactor, and divides the evenly distributed lifting plate 2 into multiple sections of equal length.

[0010] Preferably, the total axial length of the equidistant spiral plates 3 is equal to the total axial length of the rotary reactor barrel 1, the pitch of the equidistant spiral plates 3 is 10% to 20% of the total axial length of the rotary reactor barrel 1, the thickness of the equidistant spiral plates 3 is equal to the wall thickness of the rotary reactor barrel 1, and the plate width of the equidistant spiral plates 3 in the radial direction is 1 / 4 of the inner diameter of the rotary reactor barrel 1.

[0011] Preferably, the length of the evenly distributed lifting plate 2 along the axial direction of the rotary reactor cylinder 1 is consistent with the axial length of the rotary reactor cylinder 1, the length of the evenly distributed lifting plate 2 along the radial direction of the rotary reactor cylinder 1 is 1 / 4 of the diameter of the rotary reactor cylinder 1, and the thickness of the evenly distributed lifting plate 2 is equal to the wall thickness of the rotary reactor cylinder 1.

[0012] Preferably, the high-temperature smelting slag is non-ferrous metal slag produced by non-ferrous metal smelting, including copper slag, lead slag, zinc slag and nickel slag, and the particle size of the high-temperature smelting slag is 1 to 40 mm.

[0013] Preferably, the biomass material is one or more of crop waste, forestry waste, wood waste, and organic solid waste, and the particle size of the biomass material is 1 to 10 mm.

[0014] Preferably, during the reaction process, the rotation speed of the rotary reactor cylinder 1 is 1 to 5 r / min.

[0015] Preferably, the temperature of the high-temperature smelting slag is 500-1000°C, and the temperature of the biomass material is room temperature.

[0016] Preferably, the biomass material and the high-temperature smelting slag are fed at the same time and stopped at the same time, and the feed mass ratio of the biomass material to the high-temperature smelting slag is 0.1:1.

[0017] Beneficial effects of the present invention:

[0018] The present invention optimizes the structure to be suitable for heat transfer reaction between high-temperature smelting slag and biomass materials by specially designing the internal structure of the rotary reactor, thereby enhancing the heat transfer efficiency in the co-pyrolysis process of high-temperature smelting slag and biomass, improving the utilization rate of waste heat of high-temperature smelting slag, and at the same time improving the reaction efficiency, reducing the processing cost, and truly achieving the purpose of efficiently treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the internal structure of a rotary reactor according to Example 1 of the present invention;

[0020] Figure 2 This is a schematic side view of the internal structure of the rotary reactor of Example 1 of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal structure of a rotary reactor according to Example 2 of the present invention;

[0022] Figure 4 It is a schematic side view of the internal structure of the rotary reactor of Example 2 of the present invention;

[0023] Figure 5 This is a schematic diagram of the internal structure of a rotary reactor of Comparative Example 1 of the present invention;

[0024] Figure 6 This is a schematic side view of the internal structure of the rotary reactor of Comparative Example 1 of the present invention;

[0025] Figure 7 This is a schematic diagram of the internal structure of the rotary reactor of Comparative Example 2 of the present invention;

[0026] Figure 8 This is a schematic diagram of the internal structure of the rotary reactor of Comparative Example 3 of the present invention;

[0027] Fig. 9 It is a schematic side view of the internal structure of the rotary reactor of Comparative Example 3 of the present invention;

[0028] Fig.10 This is a schematic diagram of the internal structure of a rotary reactor of Comparative Example 4 of the present invention;

[0029] Fig.11 It is a schematic side view of the internal structure of the rotary reactor of Comparative Example 4 of the present invention;

[0030] Fig.12 This is a schematic diagram of the internal structure of a rotary reactor of Comparative Example 5 of the present invention;

[0031] Fig.13 The temperature changes of biomass particles in the first 300 seconds in Examples 1-2 and Comparative Examples 1-4 are shown.

[0032] Fig.14The temperature changes of biomass particles in the first 300 seconds in Examples 2-7 and Comparative Examples 6-7 are shown.

[0033] Fig.15 The temperature changes of biomass particles in the first 300 seconds in Examples 2, 8, 9 and Comparative Examples 8-9 are shown.

[0034] In the figure, 1-rotary reactor cylinder, 2-evenly distributed lifting plates, 3-equidistant spiral plates. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with specific embodiments.

[0036] In the embodiments of the present invention and the comparative examples, the professional particle heat transfer research software EDEM is used for modeling and the model parameters are set. The high-temperature smelting slag is set to copper slag with an average particle size of 5 mm, and the biomass material is set to waste cigarette rods with an average particle size of about 5 mm. The density of the copper slag is set to 3150 kg / m 3 , the specific heat capacity is 1100 J / (kg·K), the thermal conductivity is 6 m·K; the density of the discarded cigarette rod is 220 kg / m 3 , specific heat capacity is 960 J / (kg·K), and thermal conductivity is 0.17 m·K.

[0037] Example 1 (such as Figure 1-2 (shown)

[0038] In this embodiment, high temperature smelting slag and biomass are co-pyrolyzed by the following method:

[0039] The temperature parameter of the high-temperature smelting slag is set to 900°C, the internal structure of the rotary reactor is set to 6 evenly distributed lifting plates 2, and the size parameters of the rotary reactor cylinder 1 are set to 1000mm in length, 200mm in diameter, and 5mm in wall thickness. The high-temperature smelting slag feed rate is 15kg / h, and the biomass particle feed rate is 1.5kg / h. In the same time, the feed mass ratio of biomass particles to high-temperature smelting slag is 0.1:1. The rotary reactor rotates at a speed of 3r / min during the pyrolysis process, and the reaction time is 5min.

[0040] Example 2 (such as Figure 3-4 (shown)

[0041] In this embodiment, high temperature smelting slag and biomass are co-pyrolyzed by the following method:

[0042] This embodiment and Example 1 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, with the difference that: in this embodiment, equidistant spiral plates 3 and evenly distributed lifting plates 2 are arranged in the rotary reactor cylinder 1, wherein the pitch of the equidistant spiral plates is 100 mm, which is 10% of the axial length of the rotary reactor cylinder 1.

[0043] Example 3

[0044] This embodiment and embodiment 2 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the number of evenly distributed lifting plates 2 is 3.

[0045] Example 4

[0046] This embodiment and embodiment 2 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the number of evenly distributed lifting plates 2 is 4.

[0047] Example 5

[0048] This embodiment and embodiment 2 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the number of evenly distributed lifting plates 2 is 5.

[0049] Example 6

[0050] This embodiment and embodiment 2 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the number of evenly distributed lifting plates 2 is 7.

[0051] Example 7

[0052] This embodiment and embodiment 2 use the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the number of evenly distributed lifting plates 2 is 8.

[0053] Example 8

[0054] This embodiment and embodiment 2 adopt the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the pitch of the equidistant spiral plates is 15% of the axial length of the rotary reactor cylinder 1, i.e., 150 mm.

[0055] Example 9

[0056] This embodiment and embodiment 2 adopt the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the pitch of the equidistant spiral plates is 20% of the axial length of the rotary reactor cylinder 1, i.e., 200 mm.

[0057] Comparative Example 1 (such as Figure 5-6 (shown)

[0058] This comparative example adopts the same method as Example 1 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: in this comparative example, the high-temperature smelting slag and biomass particles are added to a rotary reactor with only equidistant spiral plates arranged inside.

[0059] Comparative Example 2 (such as Figure 7 (shown)

[0060] This comparative example adopts the same method as Example 1 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: in this comparative example, the high-temperature smelting slag and biomass particles are added to a rotary reactor with a smooth inner wall, and there are no other components inside the rotary reactor cylinder 1.

[0061] Comparative Example 3 (such as Figure 8-9 (shown)

[0062] This comparative example adopts the same method as Example 1 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: the high-temperature smelting slag and biomass particles in this comparative example are added to a rotary reactor with a variety of irregular finned lifting plates arranged inside.

[0063] Comparative Example 4 (such as Figure 10-11 (shown)

[0064] This comparative example adopts the same method as Example 1 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: the high-temperature smelting slag and biomass particles in this comparative example are added into a rotary reactor with a regular finned lifting plate arranged inside.

[0065] Comparative Example 5 (such as Fig.12 (shown)

[0066] This comparative example adopts the same method as Example 2 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: the high-temperature smelting slag and biomass particles in this comparative example are added to a rotary reactor with equidistant spiral plates and lifting plates arranged inside, and at the same time, the lifting plates between the spirals of the equidistant spiral plates are staggered and not in a straight line.

[0067] Compared with Example 2, the heat transfer efficiency in this comparative example is lower, which shows that the internal structure design of the rotary furnace of the present invention can significantly improve the heat transfer effect between high-temperature smelting slag and biomass particles.

[0068] Comparative Example 6

[0069] This comparative example adopts the same method as that in Example 2 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: in this comparative example, there is only one evenly distributed lifting plate in the rotary reactor cylinder.

[0070] Comparative Example 7

[0071] This comparative example adopts the same method as that of Example 2 to carry out co-pyrolysis of high-temperature smelting slag and biomass particles, except that: there are two evenly distributed lifting plates in the rotary reactor cylinder of this comparative example.

[0072] Comparative Example 8

[0073] This embodiment and embodiment 2 adopt the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the pitch of the equidistant spiral plates is 5% of the axial length of the rotary reactor cylinder 1, i.e., 50 mm.

[0074] Comparative Example 9

[0075] This embodiment and embodiment 2 adopt the same method to carry out co-pyrolysis of high-temperature smelting slag and biomass, the difference being that in this embodiment, the pitch of the equidistant spiral plates is 25% of the axial length of the rotary reactor cylinder 1, i.e., 250 mm.

[0076] pass Fig.13 It can be seen that the heating rate of the biomass particles in Examples 1 and 2 is significantly improved compared with Comparative Examples 1-4, indicating that the internal structure design of the rotary reactor of the present invention can effectively improve the heat transfer efficiency during the co-pyrolysis of high-temperature smelting slag and biomass particles.

[0077] pass Fig.14 It can be seen that the heating rate of the biomass particles in Examples 2-7 is significantly improved compared with that in Comparative Examples 6-7. The heating rates of Examples 2-7 in the figure are relatively similar, and some overlap occurs in the figure. However, the heating rate of the biomass particles in Comparative Examples 6-7 is significantly different from that of the biomass particles in Examples 2-7, which is significantly lower than that in Examples 2-7. This shows that the rotary reactor structure of the present invention can significantly improve the heat transfer efficiency in the process of co-pyrolysis of high-temperature smelting slag and biomass. At the same time, by Fig.15 It can also be seen that as the number of evenly distributed lifting plates increases, the heat transfer efficiency will increase, and when the number of evenly distributed lifting plates exceeds 6, the heat transfer efficiency decreases, and when the number of evenly distributed lifting plates is 8, the degree of decrease relative to the structure of 6 evenly distributed lifting plates is greater than when the number of evenly distributed lifting plates is 7. Therefore, further increasing the number of evenly distributed lifting plates will have a greater negative impact on the heat transfer efficiency.

[0078] pass Fig.15 It can be seen that with the increase of the pitch of the equidistant spiral plate, the heating rate of the biomass particles decreases. Therefore, the pitch of the equidistant spiral plate should be kept in a small range. When the pitch of the equidistant spiral plate is 5% of the axial length of the rotary reactor barrel 1, the required heat transfer time is too long, and the entire heat transfer process cannot be completed within 300 seconds. The production process takes a long time and the production efficiency is relatively low. Therefore, the pitch of the equidistant spiral plate is controlled within 10-20% of the axial length of the rotary reactor barrel 1.

[0079] In summary, the present invention significantly improves the heat transfer efficiency of high-temperature smelting slag and biomass materials during the reaction process in the rotary reactor by optimizing the internal structure of the rotary reactor, thereby completing the reaction process in a shorter time, which is beneficial to improving the overall production efficiency and is suitable for industrial promotion.

[0080] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for enhancing heat transfer of high-temperature smelting slag and biomass co-pyrolysis, characterized in that: The heat transfer enhancement method comprises controlling the feed rate, adding the biomass material and the high-temperature smelting slag into the rotary reactor cylinder (1), arranging an evenly distributed lifting plate (2) on the inner wall of the rotary reactor, wherein the evenly distributed lifting plates (2) are 5 to 8 and evenly distributed along the circumference of the rotary reactor, and the rotary reactor is also provided with an equidistant spiral plate (3), wherein the equidistant spiral plate (3) is fixedly connected to the inner wall of the rotary reactor, and the evenly distributed lifting plates (2) are divided into multiple sections of equal length by the equidistant spiral plate (3), wherein the total axial length of the equidistant spiral plate (3) is equal to the total axial length of the rotary reactor cylinder (1), the pitch of the equidistant spiral plate (3) is 10% to 20% of the total axial length of the rotary reactor cylinder (1), the thickness of the equidistant spiral plate (3) is equal to the wall thickness of the rotary reactor cylinder (1), and the radial plate width of the equidistant spiral plate (3) is 1 / 4 of the inner diameter of the rotary reactor cylinder (1).

2. The method for enhancing heat transfer of high temperature smelting slag and biomass co-pyrolysis according to claim 1, characterized in that: The length of the evenly distributed lifting plate (2) along the axial direction of the rotary reactor cylinder (1) is consistent with the axial length of the rotary reactor cylinder (1), the length of the evenly distributed lifting plate (2) along the radial direction of the rotary reactor cylinder (1) is 1 / 4 of the diameter of the rotary reactor cylinder (1), and the thickness of the evenly distributed lifting plate (2) is equal to the wall thickness of the rotary reactor cylinder (1).

3. The method for enhancing heat transfer of high-temperature smelting slag and biomass co-pyrolysis according to claim 1, characterized in that: The high-temperature smelting slag is non-ferrous metal slag produced by non-ferrous metal smelting, including copper slag, lead slag, zinc slag and nickel slag. The particle size of the high-temperature smelting slag is 1 to 40 mm.

4. The method for enhancing heat transfer of high-temperature smelting slag and biomass co-pyrolysis according to claim 1, characterized in that: The biomass material is one or more of crop waste, forestry waste, wood waste, and organic solid waste, and the particle size of the biomass material is 1 to 10 mm.

5. The method for enhancing heat transfer of co-pyrolysis of high-temperature smelting slag and biomass according to claim 1, characterized in that: During the reaction process, the rotation speed of the rotary reactor cylinder (1) is 1 to 5 r / min.

6. The method for enhancing heat transfer of high temperature smelting slag and biomass co-pyrolysis according to claim 1, characterized in that: The temperature of the high-temperature smelting slag is 500-1000° C., and the temperature of the biomass material is room temperature.

7. The method for enhancing heat transfer of high temperature smelting slag and biomass co-pyrolysis according to claim 1, characterized in that: The biomass material and the high-temperature smelting slag are fed at the same time and stopped at the same time, and the feed mass ratio of the biomass material to the high-temperature smelting slag is 0.1:1.

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