30-ton activated carbon regeneration method

Abstract

The present application provides a 30-ton-level activated carbon regeneration method, which relates to the field of solid waste treatment. The 30-ton-level activated carbon regeneration method includes: under an inert gas atmosphere, heat-treating the activated carbon to be regenerated in a reactor to obtain regenerated activated carbon. The 30-ton-level activated carbon regeneration method provided by the present application reduces the regeneration temperature, protects the strength of the regenerated activated carbon, weakens the residue of ash, and improves the adsorption activity of regeneration. At the same time, it solves the problem that the performance of the activated carbon decreases with the number of regeneration times due to repeated regeneration.

Description

Technical Field

[0001] This application relates to the field of solid waste treatment, and particularly to a method for regenerating 30-ton activated carbon. Background Art

[0002] Due to its special microcrystalline structure and large specific surface area, activated carbon is a commonly used and effective adsorbent. The application fields of activated carbon are becoming increasingly extensive, and the annual usage in various industries is quite considerable. However, since activated carbon is prone to saturation and loss of adsorption capacity during use, it loses its activity, so it must be replaced frequently. Each time new carbon is replaced, the economic cost will increase. Moreover, for saturated activated carbon, if it is directly discarded, it will cause great waste. If it is incinerated, a large amount of carbon dioxide and adsorbate waste gas will be generated, causing secondary pollution to the environment. Therefore, it is necessary to consider the recycling and reuse of saturated activated carbon. Recycling can greatly reduce resource consumption, reduce economic losses, and also reduce air pollution caused by activated carbon. Therefore, the regeneration of activated carbon has strong economic and environmental benefits.

[0003] The regeneration of activated carbon refers to the process of removing the adsorbate adsorbed in the pores of activated carbon and restoring its adsorption performance by physical or chemical methods without destroying its original structure.

[0004] The existing process generally adopts the rotary kiln regeneration process, and the highest treatment temperature generally needs to reach 900°C. This traditional process has problems such as complex process and generation of a large amount of flue gas. In addition, the high combustion temperature is likely to cause carbonization of the organic matter adsorbed by activated carbon, block the pores, and at the same time, it is easy to cause mechanical wear, resulting in a decrease in the mechanical strength of the regenerated activated carbon.

[0005] At the same time, the above process is not suitable for powdered activated carbon; moreover, in the case of adopting this process, the number of repeated regenerations of activated carbon is small, and the number of repeated uses of activated carbon is limited. Summary of the Invention

[0006] The purpose of this application is to provide a method for regenerating 30-ton activated carbon to solve the above problems.

[0007] To achieve the above purpose, this application adopts the following technical solutions:

[0008] A method for regenerating 30-ton activated carbon, comprising:

[0009] Under an inert gas atmosphere, heat-treat the activated carbon to be regenerated in a reactor to obtain regenerated activated carbon;

[0010] The heat treatment includes:

[0011] Low-temperature stage: Heat up from room temperature to 200°C within 4 hours, and then heat up from 200°C to 330°C within 4 hours;

[0012] High-temperature stage: When the activated carbon is coal-based activated carbon, it is heated from 330°C to 380°C within 2 hours, and kept at 380°C for 1 hour; heated to 420°C within 2 hours, and kept at 420°C for 1 hour; heated to 480°C within 2 hours, and kept at 480°C for 2 hours; heated to 520°C within 2 hours, and kept at 520°C for 2 hours; heated to 560°C within 2 hours, and kept at 560°C for 2 hours; heated to 600°C within 2 hours, and kept at 600°C for 4 hours. When the activated carbon is wood-based activated carbon, it is heated from 330°C to 380°C within 2 hours, and kept at 380°C for 1 hour; heated to 420°C within 2 hours, and kept at 420°C for 2 hours; heated to 480°C within 2 hours, and kept at 480°C for 4 hours; heated to 520°C within 2 hours, and kept at 520°C for 4 hours; heated to 560°C within 2 hours, and kept at 560°C for 4 hours; heated to 600°C within 2 hours, and kept at 600°C for 4 hours.

[0013] Cooling stage: After the regeneration is completed, it is cooled to room temperature in an inert gas atmosphere.

[0014] Preferably, the inert gas is nitrogen.

[0015] Preferably, the nitrogen is continuously introduced into the reactor.

[0016] Preferably, the flow rate of the nitrogen is controlled by two roots blowers with different powers and flow rates, and the operating pressure of the reactor is 0.6 MPa.

[0017] Preferably, before the nitrogen enters the reactor, it is heated by a heat exchanger and a heating furnace in sequence, and the heating rate of the heating furnace is 10 - 15°C / h.

[0018] Preferably, the desorbed gas generated by the reactor passes through a heat exchanger and a cooler and then enters a separator for separation. The nitrogen continues to circulate, and the waste gas enters a tail gas absorption tank.

[0019] Preferably, during the heat treatment process, as the inert gas is conveyed into the reactor

[0020] Preferably, the cooling is carried out in an inert gas atmosphere.

[0021] Preferably, screening is also included after the heat treatment.

[0022] Preferably, a cavity grille and a gas path cavity are arranged in the reactor.

[0023] Compared with the prior art, the beneficial effects of the present application include:

[0024] The 30-ton activated carbon regeneration method provided by this application adopts the off-line fixed bed technology, uniformly heats and regenerates under the protection of inert gas nitrogen, reduces the traditional technological steps, and reduces the cost. This technology reduces the regeneration temperature, protects the strength of the regenerated activated carbon, weakens the residue of ash, and improves the adsorption activity of regeneration. At the same time, it solves the problem that the performance of activated carbon decreases with the number of regeneration times due to repeated regeneration. The heating and regeneration process with inert gas protection circulates the tail gas to the heat exchanger, reducing the pollution of tail gas emissions. This process reduces the mechanical loss of activated carbon and improves the regeneration efficiency.

[0025] For different sources of activated carbon, corresponding heat treatment processes are involved, and the purpose of effective regeneration of activated carbon from different sources can be achieved when using the same set of devices. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0027] Figure 1 Schematic diagram of the device used for the 30-ton activated carbon regeneration method provided for the embodiment;

[0028] Figure 2 Partial cross-sectional view of the reactor;

[0029] Figure 3 Temperature comparison diagram of whether the gas path cavity and cavity grille are set or not. Detailed Embodiments

[0030] The implementation schemes of this application will be described in detail below in combination with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate this application and should not be regarded as limiting the scope of this application. For those without specific conditions indicated in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments without the indicated manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0031] Example 1

[0032] Figure 1 Schematic diagram of the device used for the 30-ton activated carbon regeneration method provided for this embodiment.

[0033] The device includes a first Roots blower 1, a second Roots blower 2, a heat exchanger 3, a heating furnace 4, a reactor 5, a cooler 6, a separator 7, and a tail gas absorption tank 8.

[0034] Figure 2 Partial cross-sectional view of the reactor 5.

[0035] The reactor 5 is provided with a gas path cavity 51 and a cavity grid 52.

[0036] Select the deactivated bituminous coal-based activated carbon as the regeneration raw material, and its indicators are shown in Table 1 below:

[0037] Table 1 Partial index data of a certain deactivated bituminous coal-based activated carbon

[0038] Index Deactivated activated carbon Appearance Turned white and moldy <![CDATA[Specific surface area, (m 2 / g)]]> 96.12 Iodine value, (mg / g) 202 pH 10

[0039] The 30-ton activated carbon regeneration method provided in this embodiment includes the following steps:

[0040] First, conduct nitrogen replacement: successively turn on the air compressor, refrigerating machine, nitrogen generator, and nitrogen input device until the nitrogen concentration is qualified up to 99.9%, and the oxygen content in the detection system is less than or equal to 0.5%, then the nitrogen replacement is completed.

[0041] Boost the pressure to 0.6 MPa, stop nitrogen supply, turn on the circulation machine, send nitrogen into the heat exchanger 3, and at the same time turn on the heating furnace 4 to heat the nitrogen, and control the heating rate of the heating furnace 4 to be 10 - 15 °C / h. Check the working state of the heating furnace 4 once an hour, including the maximum temperature of the furnace tubes, the furnace outlet temperature, etc., and control the error between the furnace outlet temperature and the index conditions not to exceed 2 °C. During the constant temperature process, drain water from each drain port of the cold high-pressure separator (sometimes a small amount of water will be generated during the regeneration temperature rise).

[0042] Adjust the nitrogen flow rate through the first Roots blower 1 (75 kw, flow rate 50 m 3 / min) and the second Roots blower 2 (200 kw, flow rate 112 m 3 / min) to meet the requirements of the following heat treatment process:

[0043] Low-temperature stage: Heat up from room temperature to 200 °C within 4 hours, and then heat up from 200 °C to 330 °C within 4 hours;

[0044] High-temperature stage: Heat up from 330 °C to 380 °C within 2 hours, keep the temperature constant at 380 °C for 1 hour; heat up to 420 °C within 2 hours, keep the temperature constant at 420 °C for 1 hour; heat up to 480 °C within 2 hours, keep the temperature constant at 480 °C for 2 hours; heat up to 520 °C within 2 hours, keep the temperature constant at 520 °C for 2 hours; heat up to 560 °C within 2 hours, keep the temperature constant at 560 °C for 2 hours; heat up to 600 °C within 2 hours, keep the temperature constant at 600 °C for 4 hours;

[0045] The regeneration device has a very advanced sensing and control system, making it very convenient to control the temperature operation. Desorption is carried out in an inert high-temperature gas atmosphere, effectively preventing the "temperature runaway phenomenon" caused by exothermic reactions, and also preventing partial adsorbate carbonization and coking as the temperature continues to rise, which would block the activated carbon pores. As the temperature rises, part of the adsorbate is desorbed by high-temperature gasification, and part undergoes decomposition reactions to generate small molecules and desorb. The isothermal stage aims to clean the activated carbon pores with inert high-temperature gas to restore its adsorption performance. Activating the activated carbon in an inert gas environment does not cause mechanical loss and also weakens the phenomenon of high-temperature carbonization of the activated carbon. The strength of the regenerated activated carbon is almost equal to that of the new activated carbon.

[0046] Cooling stage: Cool to room temperature.

[0047] During the whole treatment process, nitrogen is heated by the heating furnace 4, enters the reactor 5 from the top, purges the activated carbon to be treated, and then the desorbed gas is output from the bottom to the heat exchanger 3, where it exchanges heat with fresh nitrogen and recycled nitrogen, then enters the cooler 6 for cooling, and then enters the separator 7 for separation to obtain recycled nitrogen and tail gas containing impurities. After the tail gas enters the tail gas absorption tank 8, the harmful substances are absorbed by the absorption liquid therein, and the remaining gas is discharged up to standard; the recycled nitrogen returns to the pipeline, mixes with fresh nitrogen, and then enters the heat exchanger 3 again under the action of the second Roots blower 2.

[0048] A large amount of heat is released during the reaction process, which will cause the gas temperature to rise. Therefore, the gas can be recycled to the heat exchanger 3, reducing energy consumption and the emission of waste gas.

[0049] After cooling, it passes through the sieve section of the reactor 5, and the regenerated carbon with qualified mesh number is directly packaged.

[0050] Compare the regenerated activated carbon after the treatment of this embodiment with the new activated carbon of the same batch. The results are shown in Table 2 below:

[0051] Table 2 Comparison of physical and chemical properties

[0052] Index New activated carbon Activated carbon after the first regeneration <![CDATA[Specific surface area, (m 2 / g)]]> 969 910 Iodine value, (mg / g) 820 807 pH 6.7 6.7

[0053] As can be seen from Table 2, the relevant physical and chemical indexes of the regenerated activated carbon obtained by using the method provided in this application are basically equivalent to those of the new activated carbon (unused). Indexes such as iodine value and specific surface area are relatively stable. Among them, the iodine value recovery rate reaches 98% of the new carbon, indicating that the method provided in this application achieves excellent regeneration effect under simple process conditions.

[0054] To further prove the advantages of the method provided by this application, a repeated regeneration test was conducted on the above-mentioned regenerated activated carbon (using the effluent from the secondary treatment of a certain sewage treatment plant during adsorption). Through the test, the regeneration times of the activated carbon provided by this application can reach 6 - 10 times. Table 3 below shows the relevant indicators of the activated carbon after 6 regenerations:

[0055] Table 3 Relevant indicators of activated carbon after 6 regenerations

[0056] Index Activated carbon after the first regeneration Activated carbon after the sixth regeneration <![CDATA[Specific surface area, (m 2 / g)]]> 910 830 Iodine value, (mg / g) 807 710 pH 6.7 6.7

[0057] As can be seen from Table 3 above, after 6 regenerations, the specific surface area and iodine value of the activated carbon only decreased slightly, and it still had good adsorption performance. In the prior art, the relevant indicators of general activated carbon would seriously decline after 3 regenerations, while the theoretical regeneration times of this application can reach 10 times, which is significantly better than the existing regeneration technology.

[0058] Example 2

[0059] The difference from Example 1 is that the raw material is the wood-based activated carbon to be treated, and the relevant indicators are shown in Table 4:

[0060] Table 4 Partial indicators of a certain wood-based deactivated activated carbon

[0061] Index Deactivated activated carbon Appearance Obvious oil stain <![CDATA[Specific surface area, (m 2 / g)]]> 78.5 Iodine value, (mg / g) 189 pH 3

[0062] The temperature control program during the heat treatment process is as follows:

[0063] Low-temperature stage: Heat up from room temperature to 200°C within 4 hours, and then heat up from 200°C to 330°C within 4 hours;

[0064] High-temperature stage: Heat up from 330°C to 380°C within 2 hours, keep the temperature constant at 380°C for 1 hour; heat up to 420°C within 2 hours, keep the temperature constant at 420°C for 2 hours; heat up to 480°C within 2 hours, keep the temperature constant at 480°C for 4 hours; heat up to 520°C within 2 hours, keep the temperature constant at 520°C for 4 hours; heat up to 560°C within 2 hours, keep the temperature constant at 560°C for 4 hours; heat up to 600°C within 2 hours, keep the temperature constant at 600°C for 4 hours;

[0065] Cooling stage: Cool down to room temperature after the regeneration ends.

[0066] Apply the regenerated activated carbon obtained in Example 2 to the experiment of the effluent from the secondary treatment of a certain sewage treatment plant (the same as the regeneration test in Example 1 above) to test the regeneration performance of the activated carbon. The water quality indicators of the sewage inlet and outlet are shown in Table 5.

[0067] Table 5 Water quality indicators of the inlet and secondary treatment effluent

[0068]

[0069] As can be seen from the data in Table 5, during the secondary treatment of the effluent from a certain sewage treatment plant by the regenerated activated carbon, the sewage treatment indicators are completely qualified, meeting the discharge standards after sewage treatment, indicating that the physical and chemical indicators of the regenerated activated carbon are stable.

[0070] It should be noted that for the method provided in this application, with fixed temperature data, its industrial application is simple and convenient, and it is preferably applicable to the regeneration of coal-based activated carbon and wood-based activated carbon with a specific surface area of not less than 50 m 2 / g and an iodine value of not less than 150 mg / g. Other types of activated carbon can also be used, but generally, the temperature data needs to be re-determined and the procedure adjusted appropriately.

[0071] Comparative Example 1

[0072] Regeneration was carried out according to the traditional rotary kiln regeneration process.

[0073] Comparing the method provided in this application with the traditional rotary kiln regeneration process, the situation is as shown in Table 6 below:

[0074] Table 6 Process Comparison

[0075]

[0076] Comparative Example 2

[0077] According to the different properties of the regenerated activated carbon, under different constant temperature conditions, for the purpose of cleaning the pores of the activated carbon with inert high-temperature gas to restore its adsorption performance. If the temperature is continuously increased at a constant speed without a constant temperature time, the time for the inert gas to clean the pores of the activated carbon will be greatly reduced, and the regeneration effect will be poor. Using the same activated carbon raw material for regeneration, a comparative experiment was conducted with the regeneration conditions of this application and replacing the constant temperature activation stage with activation at a constant heating rate of 20 °C / h, and the data is as shown in Table 7 below:

[0078] Table 7 Comparison of Physical and Chemical Properties between the Constant Temperature Activation Stage and Constant Heating Rate

[0079] Index Heating up at a constant speed Constant temperature activation <![CDATA[Specific surface area, (m 2 / g)]]> 760 940 Iodine value, (mg / g) 530 817 pH 6.7 6.7

[0080] As can be seen from Table 7 above, in the regeneration method provided in this application, the setting of the constant temperature activation stage has an obvious beneficial effect on the performance of the regenerated activated carbon.

[0081] Comparative Example 3

[0082] It is generally believed in the prior art that high temperature can burn off the impurities adsorbed in the activated carbon. However, in the regeneration method provided in this application, since the treatment volume reaches the 30 t level, which is different from the several kilograms level in the laboratory, the regeneration temperature should not be too high. To more directly illustrate the influence of the maximum regeneration temperature, a comparison was specifically carried out, as shown in Table 8 below:

[0083] Table 8 Comparison of Different Maximum Regeneration Temperatures

[0084] Regeneration temperature 600°C Regeneration temperature 900°C Recovery rate of activated carbon, % ＞92 ＞90 Ash content, % 1～8 2～10 <![CDATA[Specific surface area, (m 2 / g)]]> 920 927 Iodine value, (mg / g) 810 813 pH 7.0 7.0

[0085] As can be seen from Table 8 above, after the regeneration temperature is raised to 900 °C, the index data after regeneration does not increase much. Instead, it will reduce the recovery rate of activated carbon, and the materials required for the process must be heat-resistant, increasing the economic cost.

[0086] In addition, although the yield decreased by 2%, the absolute value reached 0.6 t, that is, 600 kg of products would be less recovered each time of regeneration. Assuming 10 times of regeneration, it would have a greater impact on the overall final comprehensive recovery rate. Comparative Example 4

[0087] The reactor 5 is provided with an air path cavity 51 and a cavity grid 52, which ensures uniform heat transfer, prevents the phenomenon of temperature runaway, makes the temperature control more stable, and has a higher regeneration rate. The 100 L pilot plant in the laboratory simulates the temperature experiment, heating up to 400 °C at a speed of 100 °C / h and keeping it at 400 °C for 4 hours. The temperature change curves of the two reactors are compared as Figure 3 shown.

[0088] As Figure 3 can be seen, in the absence of the cavity air path 51 and the grid 52, the phenomenon of temperature runaway occurs in the equipment. Although Figure 3 the temperature difference is less than 40 degrees, but after reaching the 30 t scale, the temperature runaway will reach 100 - 200 degrees, and the local temperature runaway will be even higher, which will seriously affect the regeneration quality of activated carbon.

[0089] The present application has the following advantages:

[0090] ① The activated carbon regeneration technology provided by the present application adopts the offline fixed bed technology.

[0091] ② The present application designs a targeted special 30 t reactor for regeneration. The grid and the air path cavity are evenly distributed inside the reactor, and the heat transfer is uniform. The stainless steel plates used for the reactor vessel cylinder, head, etc. only need to meet the requirements of GB / T 24511 - 2017.

[0092] ③ The process parameters are combined with the inert gas circulation heating regeneration, the temperature distribution is uniform, the activated carbon is not easy to carbonize, the desorbed gas is separated with nitrogen, and the inert gas protects the device and weakens the damage degree of the waste gas to the device.

[0093] ④ The activated carbon regeneration technology provided by the present application reduces the regeneration temperature. Compared with the traditional heating regeneration process, it reduces the process steps and the operation cost.

[0094] ⑤ The activated carbon regeneration technology provided by the present application reduces the mechanical loss during the regeneration process, weakens the ash residue, protects the strength of the regenerated activated carbon, and improves the regeneration efficiency.

[0095] ⑥This application solves the problem that the performance of activated carbon decreases with the number of regeneration cycles due to repeated regeneration.

[0096] ⑦The activated carbon regeneration technology provided by this application uses inert gas protection for heating regeneration, and the tail gas is recycled to the heat exchanger, reducing the pollution of tail gas emissions.

[0097] ⑧The activated carbon regeneration technology provided by this application has convenient process operation and high automation, reducing labor costs.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0099] In addition, those skilled in the art can understand that although some of the embodiments herein include certain features included in other embodiments but not others, the combination of features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the claims above, any one of the claimed embodiments can be used in any combination. The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of this application and should not be regarded as an admission or any form of implication that this information constitutes prior art known to those skilled in the art.

Claims

1. A 30-ton activated carbon regeneration method, characterized in that, Including: Under a nitrogen atmosphere, the regenerated activated carbon is heat-treated in a reactor to obtain the regenerated activated carbon; The heat treatment includes: Low-temperature stage: Heating from room temperature to 200 °C within 4 hours, and then heating from 200 °C to 330 °C within 4 hours; High-temperature stage: When the activated carbon is coal-based activated carbon, heating from 330 °C to 380 °C within 2 hours, maintaining a constant temperature of 380 °C for 1 hour; heating to 420 °C within 2 hours, maintaining a constant temperature of 420 °C for 1 hour; heating to 480 °C within 2 hours, maintaining a constant temperature of 480 °C for 2 hours; heating to 520 °C within 2 hours, maintaining a constant temperature of 520 °C for 2 hours; heating to 560 °C within 2 hours, maintaining a constant temperature of 560 °C for 2 hours; heating to 600 °C within 2 hours, maintaining a constant temperature of 600 °C for 4 hours; when the activated carbon is wood-based activated carbon, heating from 330 °C to 380 °C within 2 hours, maintaining a constant temperature of 380 °C for 1 hour; heating to 420 °C within 2 hours, maintaining a constant temperature of 420 °C for 2 hours; heating to 480 °C within 2 hours, maintaining a constant temperature of 480 °C for 4 hours; heating to 520 °C within 2 hours, maintaining a constant temperature of 520 °C for 4 hours; heating to 560 °C within 2 hours, maintaining a constant temperature of 560 °C for 4 hours; heating to 600 °C within 2 hours, maintaining a constant temperature of 600 °C for 4 hours; Cooling stage: Cooling to room temperature after the regeneration ends; A cavity grid and an air path cavity are provided in the reactor.

2. The 30-ton activated carbon regeneration method according to claim 1, characterized in that The nitrogen is continuously introduced into the reactor.

3. The 30-ton activated carbon regeneration method according to claim 2, wherein The flow rate of the nitrogen is controlled by two Roots blowers with different powers and flow rates, and the operating pressure of the reactor is 0.6 MPa.

4. The 30-ton activated carbon regeneration method according to claim 2, characterized in that, Before the nitrogen enters the reactor, it is heated by a heat exchanger and a heating furnace in sequence, and the heating rate of the heating furnace is 10 - 15 °C / h.

5. The 30-ton activated carbon regeneration method according to claim 1, characterized in that, The desorbed gas generated by the reactor passes through a heat exchanger and a cooler and then enters a separator for separation. The nitrogen continues to circulate, and the waste gas enters a tail gas absorption tank.

6. The 30-ton activated carbon regeneration method according to claim 1, wherein During the heat treatment process, nitrogen is conveyed into the reactor.

7. The 30-ton activated carbon regeneration method according to claim 1, characterized in that, The cooling is carried out in a nitrogen atmosphere.

8. The 30-ton activated carbon regeneration method according to claim 1, characterized in that Screening is also included after the heat treatment.

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