Municipal solid waste analysis method and high-quality utilization treatment method

Abstract

The invention relates to a municipal solid waste analysis method and a high-quality utilization treatment method.The municipal solid waste analysis method comprises the following steps that S1, municipal solid waste raw materials are crushed and screened and then dried to remove moisture, and a to-be-detected sample is obtained; s2, carrying out industrial analysis and calorific value analysis on a to-be-detected sample to obtain the weight W1, the volatile component content V1 and the calorific value Q1 of the sample; s3, a to-be-detected sample is taken and subjected to multiple heating experiments in the inert atmosphere, and the weight Wt, the volatile component content Vt and the calorific value Qt of the product are obtained; and S4, analyzing the obtained data, and screening corresponding heating temperatures as target heating temperatures under the conditions that (W1-Wt) / W1 is larger than or equal to 10% and smaller than or equal to 15%, (V1-Vt) / V1 is smaller than or equal to 10% and (Q1-Qt) / Q1 is smaller than or equal to 10%. By means of the analysis method, the appropriate target heating temperature can be obtained, and the purpose of improving the energy utilization efficiency of domestic garbage gasification hydrogen production is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of domestic waste recycling, and in particular to an analysis method and a high-quality utilization and treatment method for urban domestic waste. Background Art

[0002] With the continuous urban development and the improvement of people's living standards in China, the amount of urban domestic waste generated increases every year, and the environmental pollution problems caused by it are becoming more and more serious. Urban domestic waste is of various types and complex in composition. The growth of the amount of urban domestic waste also requires an increase in the amount of harmless treatment of waste. Traditional domestic waste treatment methods include sanitary landfill, composting, and incineration for power generation. Although these treatment methods can reduce the amount of domestic waste, they all have some problems. Landfilling will occupy a large amount of land and is difficult to select a site; the investment cost of composting treatment is high, the fertilizer efficiency is low, and it is more suitable for perishable waste; although incineration for power generation can effectively reduce the volume and weight, it will produce harmful substances such as dioxins and the economic benefits have become lower in recent years; relying solely on landfilling, composting, incineration and other methods can no longer meet the current huge demand for harmless treatment of domestic waste. It is urgent to develop new and thorough harmless domestic waste treatment technologies.

[0003] In recent years, treating domestic waste through gasification technology is an effective method. Gasification usually not only has higher efficiency in treating waste, but also has much less impact on the environment. Gasification technology has relatively broad requirements for raw materials, promotes the circular economy, and more importantly, can produce high-value-added products, one of the most important of which is hydrogen. The sources of hydrogen include coal, oil, natural gas, and renewable energy. The vast majority of hydrogen in the world is produced from fossil energy. The source of hydrogen in China is mainly coal. The process of producing hydrogen from fossil fuels has the disadvantages of high energy consumption and high pollution. However, urban domestic waste in China is rich in resources, and most of the organic matter in the waste can become raw materials for hydrogen production. Therefore, using urban domestic waste gasification to produce hydrogen is a potential route. On the one hand, it promotes waste reduction and harmlessness, and on the other hand, it turns waste into treasure and directly makes clean energy, coupling solid waste and clean energy, which not only solves urban municipal problems, but also solves the problems of urban clean energy transportation and insufficient clean energy. It is necessary to carry out a pretreatment process on the waste before gasification. Before gasification, domestic waste needs to be dehydrated and precipitated, coarsely crushed and dried, and heat-treated, etc. Among them, the heat treatment process can make the waste more homogeneous and the energy is maximally utilized. The heat treatment process can make the subsequent gasification process more stable, reduce energy loss, reduce the generation of toxic gases during gasification, and thus improve the quality of syngas, making it more suitable for subsequent energy utilization or chemical production.

[0004] However, the composition of domestic waste is relatively complex and it is difficult to homogenize. When using heat treatment to achieve homogenization, problems such as difficulty in determining appropriate treatment conditions often occur. Moreover, heat treatment will result in loss of the calorific value of domestic waste, reducing the energy utilization efficiency of subsequent gasification of domestic waste. Therefore, how to find appropriate pretreatment conditions for domestic waste to minimize calorific value loss and improve the energy utilization efficiency of domestic waste has been a problem that needs to be solved in this field. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide an analysis method and a high-quality utilization treatment method for urban domestic waste. The specific solutions are as follows:

[0006] An analysis method for urban domestic waste includes the following steps:

[0007] S1. Crush and screen the raw material of urban domestic waste, and then dry it to remove moisture to obtain a sample to be detected;

[0008] S2. Take the sample to be detected for proximate analysis and calorific value analysis to obtain the weight W1, volatile content V1 and calorific value Q1 of the sample;

[0009] S3. Take the sample to be detected and conduct multiple heating experiments in an inert atmosphere. The heating temperature is T1, 200°C ≤ T1 ≤ 300°C, and t1 is used as the temperature interval of the heating experiment, 20°C < t1 < 30°C. Observe the appearance of the sample during the heating experiment, and conduct proximate analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt and calorific value Qt of the product;

[0010] S4. Analyze the obtained data, and screen out the heating temperature corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15%, (V1 - Vt) / V1 ≤ 10%, and (Q1 - Qt) / Q1 ≤ 10% as the target heating temperature, and end the analysis;

[0011] If a target heating temperature cannot be screened out, then screen out the heating temperature range T2 - T3 corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15% and (V1 - Vt) / V1 ≤ 10%, 200°C ≤ T2 < T3 ≤ 300°C;

[0012] S5. Take the sample to be detected, use T2 as the starting temperature, T3 as the ending temperature, and t2 as the temperature interval, where t2 < t1, conduct a second heating experiment, and conduct proximate analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt and calorific value Qt of the product, and then perform S4.

[0013] Further, the particle size of the crushing and screening in S1 is below 40 mesh.

[0014] Further, the industrial analysis in S2 includes dry basis mass and dry basis volatile matter content. Preferably, it further includes at least one of air-dried basis moisture content, air-dried basis volatile matter content, air-dried basis ash content, dry basis volatile matter content, dry basis ash content, dry ash-free basis volatile matter content, and fixed carbon content.

[0015] Further, in S3, 22°C < t1 < 28°C, preferably, 24°C < t1 < 26°C.

[0016] Further, in S5, 1°C < t2 < 15°C, preferably, 3°C < t2 < 7°C.

[0017] The present invention also protects a method for high-quality utilization and treatment of domestic waste, which uses the target heating temperature screened by the analysis method of the urban domestic waste to heat-treat the domestic waste.

[0018] Further, the target heating temperature is 245 - 250°C.

[0019] Further, the time for heat-treating the domestic waste is 1 - 10 h.

[0020] Further, it further includes gasifying the domestic waste after heat treatment to produce hydrogen.

[0021] Further, the specific conditions for the gasification to produce hydrogen are a gasification temperature of 850 - 900°C, a gasification pressure of 0.2 - 0.3 MPa, using oxygen as the gasification agent, and adopting circulating fluidized bed gasification. Based on the calorific value of the produced H2 product and the calorific value of the urban domestic waste raw material, the energy utilization efficiency of the domestic waste is 50 - 60%.

[0022] Beneficial effects: By using the analysis method provided by the present invention, the appropriate temperature for shallow carbonization of domestic waste can be determined, with a mass loss rate of 10 - 15%, increasing the calorific value within a relatively low mass loss range, which is beneficial for subsequent gasification of urban domestic waste to produce hydrogen and improving the energy utilization efficiency. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the present invention, the drawings will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention and do not limit the present invention.

[0024] Figure 1 It is a photo of the urban domestic waste raw material provided by Embodiment 2 of the present invention;

[0025] Figure 2It is the photo of the original sample provided by Embodiment 2 of the present invention;

[0026] Figure 3 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 200 °C;

[0027] Figure 4 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 225 °C;

[0028] Figure 5 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 250 °C;

[0029] Figure 6 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 270 °C;

[0030] Figure 7 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 300 °C;

[0031] Figure 8 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 240 °C;

[0032] Figure 9 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 245 °C;

[0033] Figure 10 It is the photo of the original sample provided by Embodiment 2 of the present invention after carbonization at 255 °C. Detailed implementation manners

[0034] The preferred implementation manners of the present invention will be described in more detail below. Although the preferred implementation manners of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the implementation manners described herein. For those without specific technical or conditions noted in the examples, the techniques or conditions described in the literature in the field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchase. In the following examples, unless otherwise specified, "%" refers to weight percentage.

[0035] Example 1

[0036] An analysis method for municipal solid waste includes the following steps:

[0037] S1. Crush and screen the municipal solid waste raw materials, and then dry to remove moisture to obtain the sample to be detected;

[0038] S2. Take the sample to be tested for industrial analysis and calorific value analysis to obtain the weight W1, volatile content V1, and calorific value Q1 of the sample;

[0039] S3. Take the sample to be tested for multiple heating experiments in an inert atmosphere. The heating temperature is T1, where 200°C ≤ T1 ≤ 300°C, and t1 is the temperature interval of the heating experiment, where 20°C < t1 < 30°C. Observe the appearance of the sample during the heating experiment, and conduct industrial analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt, and calorific value Qt of the product;

[0040] S4. Analyze the obtained data, and screen out the heating temperature corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15%, (V1 - Vt) / V1 ≤ 10%, and (Q1 - Qt) / Q1 ≤ 10% as the target heating temperature, and end the analysis;

[0041] If a target heating temperature cannot be screened out, then screen out the heating temperature range T2 - T3 corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15% and (V1 - Vt) / V1 ≤ 10%, where 200°C ≤ T2 < T3 ≤ 300°C;

[0042] S5. Take the sample to be tested, use T2 as the starting temperature, T3 as the ending temperature, and t2 as the temperature interval, where t2 < t1, conduct the second heating experiment, and conduct industrial analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt, and calorific value Qt of the product, and then perform S4.

[0043] Example 2

[0044] This example uses the method in Example 1 to analyze specific municipal solid waste raw materials as follows:

[0045] Preliminarily crush and screen the municipal solid waste raw materials (see Figure 1 ), then place them in an oven at 105°C for more than 12 hours to remove moisture. The morphology of the original garbage sample after treatment is shown in Figure 2 .

[0046] The proximate analysis of the original sample is shown in Table 1.

[0047] Table 1 Proximate Analysis of the Original Sample

[0048]

[0049] The elemental analysis results of the raw material sample are shown in Table 2.

[0050] Table 2 Elemental Analysis of the Original Sample

[0051]

[0052]

[0053] The calorific value analysis results of the original sample are shown in Table 3 below.

[0054] Table 3 Calorific Value Analysis of the Original Sample

[0055]

[0056] The shallow carbonization treatment of municipal solid waste is carried out in an inert atmosphere (such as nitrogen), using a horizontal tube furnace, and the shallow carbonization time is set to 1 h. The shallow carbonization temperature starts from 200 °C and goes up to 300 °C. First, with a temperature interval of 25 °C, after finding the key carbonization temperature range, the carbonization treatment is carried out with a temperature interval of 5 °C. As Figure 3 shown, at a carbonization temperature of 200 °C, the appearance of the domestic waste changes very little, and the waste hardly undergoes carbonization; as Figure 4 shown, at a carbonization temperature of 225 °C, the color gradually becomes darker compared to 200 °C, but the degree of carbonization is small; as Figure 5 shown, at a carbonization temperature of 250 °C, the blackening degree of the waste gradually deepens; as Figure 6 shown, when the shallow carbonization temperature is 275 °C, the degree of carbonization of the waste intensifies and it almost completely turns black; as Figure 7 shown, at a carbonization temperature of 300 °C, the waste has completely turned black and the degree of carbonization is the most severe.

[0057] The proximate analysis and calorific value of the municipal solid waste samples after shallow carbonization in different temperature ranges are shown in Table 4.

[0058] Table 4 Proximate Analysis and Calorific Value of Municipal Solid Waste after Low-Temperature Shallow Carbonization

[0059]

[0060] It can be seen from Table 4 that the shallow carbonization treatment can increase the fixed carbon in the waste, improve the calorific value of the waste and reduce the volatile matter. During the carbonization process, some light volatile matter in the waste will be released, resulting in a decrease in the volatile matter, and the retention of the volatile matter is beneficial to improving the subsequent gasification efficiency and the quality of the syngas. When the carbonization temperature is within 250 °C, the loss of volatile matter is within 10%. The higher the carbonization temperature, the more the loss of volatile matter. At carbonization temperatures of 275 °C and 300 °C, the losses are 13.0% and 25.5% respectively.

[0061] The mass loss of the municipal solid waste samples before and after shallow carbonization in different temperature ranges is shown in Table 5.

[0062] Table 5 Mass Loss of Municipal Solid Waste Samples before and after Shallow Carbonization

[0063]

[0064]

[0065] As the carbonization temperature increases, the mass loss of the waste sample increases, and the higher the temperature, the more severe the mass loss. At treatment temperatures of 225 °C and below, since the degree of carbonization is very small, the mass loss is small; at a carbonization temperature of 250 °C, 13.6% is lost, less than 15%. Compared with biomass, such a weight loss belongs to a reasonable and relatively low range; at carbonization temperatures of 275 °C and 300 °C, 13.0% and 25.5% are lost respectively, and the material loss is relatively large, which is an undesirable result in actual production.

[0066] The best shallow carbonization treatment is to maximize the retention of the material quality while increasing the calorific value. Initially judged, a reasonable optimal shallow carbonization temperature should be around 250 °C. After further treating the sample at a temperature interval of 5 °C, the appearance of the sample is as Figures 8 - 10 shown. It can be seen that as the carbonization temperature increases, the overall color gradually deepens, and the degree of carbonization at 240 °C is obviously smaller than that of others.

[0067] The mass loss of the domestic waste sample before and after carbonization near the optimal shallow carbonization temperature is shown in Table 6.

[0068] Table 6 Mass Loss of Domestic Waste Sample Before and After Treatment Near the Optimal Shallow Carbonization Temperature

[0069]

[0070] It can be seen that the loss of waste at a treatment temperature of 240 °C is less than that of others because its degree of carbonization is not deep. The overall mass loss rate is relatively low near the optimal shallow carbonization temperature, within 10 - 15%, and only the mass loss at a carbonization temperature of 255 °C is relatively large.

[0071] The volatile matter and calorific value of the material at different shallow carbonization treatment temperatures are analyzed as shown in Table 7 below.

[0072] Table 7 Analysis of Volatile Matter and Calorific Value of Samples Near the Optimal Shallow Carbonization Temperature

[0073]

[0074] The overall calorific value near the optimal shallow carbonization temperature is higher than that of the original waste. The loss of volatile matter is relatively low. Generally speaking, 245 - 250 °C is the optimal treatment temperature range for the shallow carbonization of domestic waste, which is more suitable for subsequent hydrogen production by gasification.

[0075] Example 3

[0076] In this embodiment, 400 tons of municipal solid waste is obtained. The received domestic waste is placed in a waste storage pit, and about 80 tons / day of leachate is generated through fermentation and dehydration. The remaining raw materials are fed into a crusher at a processing rate of 13.3 tons / hour for preliminary crushing, with a particle size of less than 40 mesh, and then fed into a drying unit. The dehydration rate is about 1.67 tons / hour, and the remaining materials are fed into a carbonization furnace at a processing rate of 11.66 tons / hour for shallow carbonization treatment. The temperature of the carbonization device is controlled at 245 °C. Under an inert atmosphere (nitrogen), the domestic waste is further dehydrated and shallowly carbonized, with a residence time of 1 h. After carbonization, the materials are separated by a separator to obtain metals, glass, stones, etc., and then fed into a secondary crusher for crushing to obtain 10.06 tons / hour of homogeneous gasification raw materials. The shallowly carbonized materials are fed into a circulating fluidized bed gasifier and undergo a gasification reaction with the oxygen-rich materials sent by the air separation system in the gasifier. The gasification pressure is 0.3 MPa. The content of O2 in the oxygen-rich materials is 90% (volume content), and the flow rate of the oxygen-rich materials is 5.05 tons / hour. The gasification temperature is 880 °C. After the synthesized gas obtained by gasification is purified, transformed, and separated, the produced amount of H2 is about 1202.3 kg / hour. The purity of the produced hydrogen is 99.99 wt%. Based on the calorific value of the produced H2 product and the calorific value of the municipal solid waste raw materials, the energy utilization efficiency is 54.2%.

[0077] Comparative Example 1

[0078] This comparative example refers to Example 3, with the only difference being that the temperature of the carbonization device is controlled at 240 °C, and the other conditions are the same. Finally, based on the calorific value of the produced H2 product and the calorific value of the municipal solid waste raw materials, the energy utilization efficiency is 40.3%.

[0079] Comparative Example 2

[0080] This comparative example refers to Example 3, with the only difference being that the temperature of the carbonization device is controlled at 255 °C, and the other conditions are the same. Finally, based on the calorific value of the produced H2 product and the calorific value of the municipal solid waste raw materials, the energy utilization efficiency is 41.8%.

[0081] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0082] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0083] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. An analysis method for municipal domestic waste, characterized in that: It includes the following steps: S1. Crush and screen the municipal solid waste raw materials, and then dry to remove moisture to obtain the sample to be detected; S2. Take the sample to be detected for proximate analysis and calorific value analysis to obtain the weight W1, volatile content V1 and calorific value Q1 of the sample; S3. Take the sample to be detected and conduct multiple heating experiments in an inert atmosphere. The heating temperature is T1, 200°C ≤ T1 ≤ 300°C, and t1 is the temperature interval of the heating experiment, 20°C < t1 < 30°C. Observe the appearance of the sample during the heating experiment, and conduct proximate analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt and calorific value Qt of the product; S4. Analyze the obtained data, and screen out the heating temperature corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15%, (V1 - Vt) / V1 ≤ 10%, (Q1 - Qt) / Q1 ≤ 10% as the target heating temperature, and end the analysis; If a target heating temperature cannot be screened out, then screen out the heating temperature range T2 - T3 corresponding to the conditions that simultaneously satisfy 10% ≤ (W1 - Wt) / W1 ≤ 15%, (V1 - Vt) / V1 ≤ 10%, 200°C ≤ T2 < T3 ≤ 300°C; S5. Take the sample to be detected, use T2 as the starting temperature, T3 as the ending temperature, and t2 as the temperature interval, where t2 < t1, conduct the second heating experiment, and conduct proximate analysis and calorific value analysis on the product after heating to obtain the weight Wt, volatile content Vt and calorific value Qt of the product, and then perform S4.

2. The analysis method of municipal domestic waste according to claim 1, characterized in that: The particle size of the crushing and screening in S1 is below 40 mesh.

3. The method for analyzing municipal solid waste according to claim 1 or 2, characterized in that: The proximate analysis in S2 includes dry basis mass and dry basis volatile content. Preferably, it also includes at least one of air-dried basis moisture content, air-dried basis volatile content, air-dried basis ash content, dry basis volatile content, dry basis ash content, dry ash-free basis volatile content and fixed carbon content.

4. The analysis method of municipal domestic waste according to claim 1, wherein: In S3, 22°C < t1 < 28°C, preferably, 24°C < t1 < 26°C.

5. The analysis method of municipal domestic waste according to claim 4, characterized in that: In S5, 1°C < t2 < 15°C, preferably, 3°C < t2 < 7°C.

6. A method for high-quality utilization and treatment of domestic waste, characterized in that: Use the target heating temperature screened by the analysis method of municipal solid waste described in any one of claims 1 - 5 to heat-treat the municipal solid waste.

7. The method for high-quality utilization and treatment of domestic waste according to claim 6, characterized in that: The target heating temperature is 245 - 250°C.

8. The method for high-quality utilization and treatment of domestic waste according to claim 7, characterized in that: The heating time for heat-treating the municipal solid waste is 1 - 10 h.

9. The method for high-quality utilization and treatment of domestic waste according to claim 7 or 8, characterized in that: It also includes gasifying the heat-treated municipal solid waste to produce hydrogen.

10. The method for high-quality utilization and treatment of domestic waste according to claim 9, characterized in that: The specific conditions for the hydrogen production by gasification are a gasification temperature of 850 - 900°C, a gasification pressure of 0.2 - 0.3 MPa, using oxygen as the gasification agent, adopting circulating fluidized bed gasification. Based on the calorific value of the produced H2 product and the calorific value of the municipal solid waste raw material, the energy utilization efficiency of the municipal solid waste is 50 - 60%.

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