High-strength sludge type carbon and preparation method thereof

Abstract

The invention discloses high-strength sludge type carbon and a preparation method thereof, and belongs to the technical field of clean type carbon preparation. Municipal sludge and low-rank coal are used as main raw materials, different types of binders with different mass proportions are added, a full-automatic tablet press is used for pressing the mixed material into sludge briquette coal under a certain forming load, and low-temperature pyrolysis is performed in a fixed bed reactor at a certain heating rate and a certain pyrolysis temperature to prepare the high-strength sludge briquette coal. According to the invention, the cold pressing strength of the sludge type carbon is improved, so that the sludge type carbon meets the strength requirements of related technologies. The invention provides a clean and efficient method for resource utilization of municipal sludge.

Description

Technical Field

[0001] The invention belongs to the technical field of clean carbon preparation, and in particular relates to high-strength sludge carbon and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of urbanization, the number of sewage treatment plants in cities has also increased sharply. However, it has not only improved the sewage problem, but also brought more serious sludge environmental pollution. As of 2023, my country has built more than 2,900 urban sewage treatment plants, with a sewage treatment capacity of more than 226 million m 3 / d, the annual output of urban dry sludge in China has also increased rapidly, and the annual output of dry sludge in China will reach 15.054 million tons / year in 2023. At present, my country's sludge treatment methods include sanitary landfill, incineration, building materials utilization, land utilization and stacking, but all of them will cause inevitable secondary harm to the environment. Therefore, a clean, efficient and resource-based sludge treatment method is urgently needed.

[0003] Dry sludge is a raw material that contains energy equivalent to fossil energy such as coal, but due to its high degree of dispersion and large differences in properties, it is difficult to convert and utilize alone. Since the sludge has high volatile matter and pyrolysis temperature range similar to low-rank coal, and has a certain degree of cohesiveness. On the other hand, my country has abundant reserves of low-rank coal, and the molding pyrolysis technology of low-rank coal is relatively mature. It is possible to consider coupling sludge and low-rank coal molding to prepare high-strength sludge charcoal by synergistic pyrolysis. This technology can not only make full use of carbon resources and reduce the consumption of fossil energy, but also avoid the formation of secondary waste, and realize the clean and efficient utilization of waste carbon-containing resources, thus bringing good economic, social and ecological benefits. The prepared high-strength sludge charcoal can be used in the fields of polluted gas adsorbent, fixed bed gasification and solid fuel. However, these application scenarios have certain technical requirements for the cold pressing strength of sludge charcoal, that is, the cold pressing strength is greater than 800N / piece (derived from the coal industry standard "Technical Conditions for Coal Shaped for Fixed Bed Gasification" (MT / T 1010-2006)). In view of this, how to improve the cold pressing strength of sludge-type carbon is the key to the preparation of high-strength sludge-type carbon technology. Summary of the invention

[0004] The main purpose of the present invention is to provide a high-strength sludge-type carbon and a preparation method thereof. The present invention improves the cold-pressing strength of sludge-type carbon by adding a binder to meet the technical requirements of carbon strength, thereby achieving clean, efficient and resourceful treatment of municipal sludge.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing high-strength sludge-type carbon comprises the following steps:

[0007] Step 1: Dry the municipal sludge to a certain moisture content; crush and screen the low-rank coal to form low-rank coal powder with a certain particle size distribution; and then mix the two;

[0008] Step 2: Add binder, mix well, and press into tablets;

[0009] Step 3: After the molding is completed, a pyrolysis reaction is performed to obtain the high-strength sludge-type carbon.

[0010] Preferably, the water content of the municipal sludge in step 1 is 10%-20%.

[0011] Preferably, the particle size distribution of the low-rank coal powder in step 1 is: R1<125μm, R2=125-380μm, R3=380-1000μm, R1 accounts for 50%, and R2 and R3 account for 25% respectively.

[0012] Preferably, in the step 1, the municipal sludge is mixed with low-rank coal powder at a mixing ratio of 50%-70% of the municipal sludge on a dry basis.

[0013] Preferably, the binder in step 2 is one of fat coal, coal tar, coal tar slag and kaolin.

[0014] Preferably, the mass proportion of the binder in step 2 is 2%-10%; more preferably, the mass proportion of the binder is 6%-10%.

[0015] Preferably, the molding load in step 2 is 14-62 MPa.

[0016] Preferably, the conditions for the pyrolysis reaction in step 3 are: the atmosphere is nitrogen, the flow rate of the nitrogen atmosphere is 100 mL / min, the heating rate is 5-20°C / min, and the pyrolysis temperature is 500-700°C.

[0017] A high-strength sludge-type carbon is prepared by the preparation method as described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention uses municipal sludge and low-rank coal as raw materials. By adding a small amount of asphalt binder, the compressive strength of sludge-type carbon can be significantly improved, so that it meets the technical requirements of the industry standard for the compressive strength of sludge-type carbon, and solves the problem that sludge-type carbon is easy to break during the application process.

[0020] (2) The main raw material of the present invention is sludge, which has low use cost, can reduce the cost of preparing high-strength sludge-type carbon, and has good economic benefits. At the same time, the molding raw materials of the present invention are mixed in a certain proportion, which has the characteristics of easy availability of raw materials, flexible ratio, simple preparation, etc.

[0021] (3) The high-strength sludge-type carbon preparation technology of the present invention is a clean and efficient sludge resource treatment technology, which solves the problem of sludge pollution to the environment and the difficulty in sludge treatment, and has good ecological benefits. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0023] Comparative Example 1

[0024] The municipal sludge is dried to a moisture content of 10%, and the low-rank coal is crushed and sieved into different particle sizes: R1 < 125μm, R2 = 125-380μm, R3 = 380-1000μm, of which R1 accounts for 50%; R2 and R3 account for 25% respectively. The municipal sludge with a moisture content of 10% and the coal powder are mixed at a mixing ratio of 50% of the municipal sludge (dry basis), and stirred for 3 minutes with an electric stirrer to fully stir the materials. Then the mixed materials are put into the mold and molded by using a fully automatic tablet press at 38MPa for 5 minutes. Then put it into a fixed bed reaction and pass 100mL / min of nitrogen, and heat it to 600℃ at a heating rate of 5℃ / min for low-temperature pyrolysis. After the pyrolysis is completed, the charcoal is naturally cooled in a nitrogen atmosphere, and taken out after natural cooling to obtain sludge charcoal.

[0025] Example 1

[0026] The municipal sludge is dried to a moisture content of 10%, and the low-rank coal is crushed and sieved into different particle sizes: R1 < 125μm, R2 = 125-380μm, R3 = 380-1000μm, of which R1 accounts for 50%; R2 and R3 account for 25% respectively. The municipal sludge with a moisture content of 10% and the coal powder are mixed at a mixing ratio of 50% of the municipal sludge (dry basis), and then 10% of the fat coal is added by mass, and it is stirred for 3 minutes with an electric stirrer to fully stir the material, and then the mixed material is put into the mold and molded at 38MPa for 5 minutes using a fully automatic tablet press. Then put it into a fixed bed reaction and pass 100mL / min of nitrogen, and heat it to 600℃ at a heating rate of 5℃ / min for low-temperature pyrolysis. After the pyrolysis is completed, the charcoal is naturally cooled in a nitrogen atmosphere, and taken out after natural cooling to obtain sludge charcoal.

[0027] Example 2

[0028] The municipal sludge is dried to a moisture content of 10%, and the low-rank coal is crushed and sieved into different particle sizes: R1 < 125μm, R2 = 125-380μm, R3 = 380-1000μm, of which R1 accounts for 50%; R2 and R3 account for 25% respectively. The municipal sludge with a moisture content of 10% and the coal powder are mixed at a mixing ratio of 50% of the municipal sludge (dry basis), and then 2% of the coal tar is added by mass, and the mixture is stirred for 3 minutes with an electric stirrer to fully stir the material, and then the mixed material is put into the mold and molded by using a fully automatic tablet press at 38MPa for 5 minutes. Then put it into a fixed bed reaction, pass 100mL / min of nitrogen, and heat it to 600℃ at a heating rate of 5℃ / min for low-temperature pyrolysis. After the pyrolysis is completed, the charcoal is naturally cooled in a nitrogen atmosphere, and taken out after natural cooling to obtain sludge charcoal.

[0029] Example 3

[0030] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 1, except that the fat coal added in a mass proportion of 10% is replaced by coal tar pitch in a mass proportion of 10%.

[0031] Example 4

[0032] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 1, except that the fat coal added in a mass proportion of 10% is replaced by coal tar slag in a mass proportion of 10%.

[0033] Example 5

[0034] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 1, except that the fat coal added in a mass proportion of 10% is replaced by kaolin in a mass proportion of 10%.

[0035] Example 6

[0036] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 2, except that the coal tar pitch added in a mass proportion of 2% is replaced by coal tar pitch added in a mass proportion of 4%.

[0037] Example 7

[0038] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 2, except that the coal tar pitch added in a mass proportion of 2% is replaced by coal tar pitch added in a mass proportion of 6%.

[0039] Example 8

[0040] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 2, except that the coal tar pitch added in a mass proportion of 2% is replaced by coal tar pitch added in a mass proportion of 8%.

[0041] Example 9

[0042] The preparation method of the sludge-type carbon in this embodiment is the same as that in Embodiment 2, except that the coal tar pitch added in a mass proportion of 2% is replaced by coal tar pitch added in a mass proportion of 10%.

[0043] Determination of cold compressive strength

[0044] According to the method specified in the industry standard "Method for Determining Cold Compression Strength of Industrial Coal Shapes" (MT / T 748-2007), the cold compression strength of the sludge-type carbons prepared in Comparative Example 1 and Examples 1-9 was measured. The results are shown in Table 1.

[0045] Table 1 Cold compression strength of sludge-type carbon under different preparation conditions

[0046]

[0047]

[0048] According to the results of Comparative Example 1 and Examples 3-5, it can be seen that the sludge-shaped carbon prepared without binder molding cannot meet the technical requirements of the industry standard for carbon strength, and adding a binder is an important step in preparing high-strength sludge-shaped carbon.

[0049] According to the results of Example 1 and Examples 3-5, it can be seen that the sludge charcoal prepared by adding fat coal does not meet the technical requirements of the industry standard for charcoal strength, while adding coal tar, coal tar slag and kaolin as binders can meet the technical requirements, and the order of improvement effect is: coal tar > coal tar slag > kaolin.

[0050] According to the results of Example 2 and Examples 6-9, it can be seen that the technical requirements of the industry standard for the strength of charcoal can be achieved by adding 6% by mass of coal tar as a binder.

[0051] The above description is only for better explaining the embodiments of the present invention, and is not intended to limit the present invention. Any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing high-strength sludge-type carbon, characterized in that: The following steps are involved: Step 1: Dry the municipal sludge to a certain moisture content; crush and screen the low-rank coal to form low-rank coal powder with a certain particle size distribution; and then mix the two; Step 2: Add binder, mix well, and press into tablets; Step 3: After the molding is completed, a pyrolysis reaction is performed to obtain the high-strength sludge-type carbon.

2. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: The water content of the municipal sludge in step 1 is 10%-20%.

3. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: In step 1, the particle size distribution of the low-rank coal powder is: R1<125μm, R2=125-380μm, R3=380-1000μm, R1 accounts for 50%, R2 and R3 account for 25% respectively.

4. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: In the step 1, the municipal sludge is measured on a dry basis, and the municipal sludge is mixed with low-rank coal powder at a mixing ratio of 50%-70% of the municipal sludge.

5. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: In step 2, the binder is one of fat coal, coal tar, coal tar slag and kaolin.

6. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: The mass proportion of the binder in step 2 is 2%-10%.

7. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: The molding load in step 2 is 14-62 MPa.

8. The method for preparing high-strength sludge-type carbon according to claim 1, characterized in that: The conditions for the pyrolysis reaction in step 3 are: the atmosphere is nitrogen, the flow rate of the nitrogen atmosphere is 100 mL / min, the heating rate is 5-20°C / min, and the pyrolysis temperature is 500-700°C.

9. A high-strength sludge-type carbon, characterized in that: The preparation method is described in any one of claims 1 to 8.

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