Activated carbon low-temperature modification method

Abstract

The invention relates to an activated carbon modification technology, particularly discloses a low-temperature modification method for activated carbon, and aims to solve the problems that the activated carbon is burnt or ignited and the actual volatile matter exceeds the standard when the size of the volatile matter after the activated carbon is modified is limited. The modification duration of the activated carbon and the oxygen-containing gas under the current working condition is reasonably and accurately controlled on the basis of the feeding state of the activated carbon, the gas inlet state of the oxygen-containing gas, the volatile matter size target value parameter after the activated carbon is modified and the like; further, effective oxygen-containing functional groups capable of improving the denitration rate of the activated carbon can be added on the activated carbon while the surface burning loss or ignition of the activated carbon is avoided and volatile matters meet the requirements, and the generation of ineffective oxygen-containing functional groups is reduced, so that the aim of improving the denitration rate of the activated carbon is fulfilled. The low-temperature modification method for the activated carbon has the advantages of safety, controllability, easiness in adjustment, low input cost, good modification effect, convenience in large-scale practice popularization and application and the like.

Description

Technical Field

[0001] The present invention relates to the production and preparation of activated carbon, and specifically to a method for low-temperature modification of activated carbon, belonging to the technical field of activated carbon modification. Background Art

[0002] The current production process of activated carbon generally includes steps such as grinding, kneading, granulation, carbonization, cooling, activation, secondary cooling, and packaging. Due to limitations in process parameters, there are certain limitations in the denitrification performance and efficiency of traditional activated carbon. In order to significantly improve the key performance index of activated carbon - the denitrification rate, a special activated carbon modification link usually needs to be introduced. This modification process involves contacting activated carbon with an oxygen-containing gas at a certain wind speed for a certain time at a specific temperature, aiming to introduce effective oxygen-containing functional groups on the surface of the activated carbon that can improve the denitrification rate. The technical level and production stability of the modification process directly determine the quality of the finished activated carbon.

[0003] The content of effective oxygen-containing functional groups is positively correlated with the denitrification rate of activated carbon and is also positively correlated with the volatile content of activated carbon. These functional groups are usually formed during the high-temperature modification process. However, during high-temperature modification, since the temperature may be close to or even exceed the ignition point of activated carbon, if the modification process parameters are not properly controlled, it may cause surface burn or even ignition of the entire activated carbon, which not only reduces the yield of activated carbon but also may pose a threat to production safety. In addition, the current modification process often only focuses on the safety of activated carbon, and rarely considers how to maximize the proportion of effective oxygen-containing functional groups in activated carbon by adjusting the modification temperature and time while ensuring safety and limiting the volatile content of the modified activated carbon, so as to significantly improve its denitrification performance. Summary of the Invention

[0004] Aiming at the problems of activated carbon burn or ignition and excessive actual volatile content during the modification of activated carbon with limited volatile content after modification, the present invention discloses a method for low-temperature modification of activated carbon. By optimizing the control of the modification conditions of the oxygen-containing gas and activated carbon in an environment below the lowest operating temperature, it is possible to increase the effective oxygen-containing functional groups that can improve the denitrification rate of activated carbon on the activated carbon with limited increase in volatile content, that is, to achieve the purpose of improving the denitrification rate of activated carbon while avoiding surface burn or ignition of activated carbon and limiting the volatile content.

[0005] To achieve the above technical objectives, the technical solutions adopted by the present invention are specifically described as follows:

[0006] A method for low-temperature modification of activated carbon, the method comprising the following steps:

[0007] 1) Contacting activated carbon with an oxygen-containing gas at a temperature below the lowest operating temperature for a modification reaction to obtain modified activated carbon.

[0008] 2) Adjust the required modification duration at the current modification temperature according to the feeding state of the activated carbon, the inlet state of the oxygen-containing gas, and the target value of the volatile matter content after the modification of the activated carbon.

[0009] Preferably, in step 2), a mathematical model for the required modification duration at the current modification temperature is established with the feeding state of the activated carbon, the inlet state of the oxygen-containing gas, and the target value of the volatile matter content after the modification of the activated carbon as variables. The mathematical model is as follows:

[0010]

[0011] In formula (1), t is the modification duration, h.

[0012] w is the safety factor, with a value ranging from 0.1 to 0.8.

[0013] K is the ignition safety index.

[0014] m is the total mass flow rate of the activated carbon, kg / h.

[0015] c is the oxygen content of the oxygen-containing gas, %(volume concentration).

[0016] s is the wind speed of the oxygen-containing gas, m / s (should be less than the safety wind speed u).

[0017] h is the thickness of the activated carbon bedding, m.

[0018] ρ is the bulk density of the activated carbon, kg / m 3 .

[0019] Q is the oxygen demand flow rate for the modification of the activated carbon, m 3 / h.

[0020] r is the modification reaction coefficient.

[0021] f is the increase in the heat storage temperature of the activated carbon, °C.

[0022] g is the increase in the temperature of the activated carbon caused by the combustion of the combustible gas in the initial volatile matter of the activated carbon, °C.

[0023] b is the modification temperature, °C.

[0024] a is the minimum operating temperature, °C.

[0025] n 1 is the ignition risk parameter, with a value ranging from 1 to 2.

[0026] n 2 is the overspeed risk parameter, with a value ranging from 1.5 to 4.

[0027] u is the safety wind speed, with a value ranging from 0.1 to 1.5 m / s.

[0028] Preferably, under the current working conditions, according to the requirement of volatile matter in the modified activated carbon, the oxygen input flow rate of the oxygen-containing gas is controlled; then:

[0029] Q = m(f 2 - f 1 ) / [ρ o (1 - f 2 )] (2).

[0030] In formula (2), Q is the oxygen demand flow rate for the modification of activated carbon, m 3 / h.

[0031] ρ o is the density of oxygen, kg / m 3 .

[0032] m is the total mass flow rate of activated carbon, kg / h.

[0033] f 1 is the initial volatile matter of activated carbon, %.

[0034] f 2 is the target value of volatile matter after the modification of activated carbon, %. It should be noted that the content of the target value of volatile matter (f 2 ) in the modified activated carbon is limited according to the specific indexes of the required modified activated carbon. For example, when the content (mass content) of the target value of volatile matter (f 2 ) in the required modified activated carbon is required to be at most 5%, then when the actual content of volatile matter (f 2 ) in the actually obtained modified activated carbon is in the range of 4.5 - 5% (preferably 4.8 - 5%), it is qualified modified activated carbon (that is, the allowable downward fluctuation value is 0.5, preferably 0.2), otherwise (f 2 > 5%) it is unqualified modified activated carbon.

[0035] Preferably, under the current working conditions, according to the required excess flow rate of oxygen in the modification reaction, the input flow rate of the oxygen-containing gas is controlled, so as to meet the requirements of activated carbon modification. Then:

[0036] q = Q × r / c (3).

[0037] In formula (3), q is the input flow rate of the oxygen-containing gas, m 3 / h.

[0038] Q is the oxygen demand flow rate for the modification of activated carbon, m 3 / h.

[0039] r is the modification reaction coefficient.

[0040] c is the oxygen content of the oxygen-containing gas, %.

[0041] Preferably, under the current working conditions, the size of the modification reaction coefficient is calculated based on the effective penetration height of the oxygen-containing gas in the activated carbon layer, and then:

[0042] r = j / c×(n 3 ^(100(h - h 0 )) + 100h 0 ) / (100h 0 ) (4).

[0043] In formula (4), j is the excess correction coefficient of the oxygen-containing gas, and its value is 0.1 - 2.

[0044] h is the thickness of the activated carbon bedding, in m.

[0045] h 0 is the effective penetration height of the oxygen-containing gas in the activated carbon layer, and its value is 0.03 - 0.1 m, h 0 ≥h.

[0046] n 3 is the effective penetration parameter, and its value is 1 - 10.

[0047] Preferably, in step 1), the lowest working condition temperature is a temperature not higher than 350 °C, preferably a temperature of 240 - 345 °C, and more preferably a temperature of 280 - 335 °C.

[0048] Preferably, during the modification process, the maximum bedding thickness of the activated carbon does not exceed 0.25 m, preferably 0.03 - 0.15 m, and more preferably 0.05 - 0.1 m.

[0049] Preferably, during the modification process, the volume content of oxygen in the oxygen-containing gas is not less than 3%, preferably 5 - 21% (such as air).

[0050] Preferably, the oxygen-containing gas is composed of one or more of oxygen, air, nitrogen, carbon dioxide, and inert gas.

[0051] Preferably, the activated carbon is carbonized activated carbon and / or activated activated carbon, preferably hot-state activated carbon after carbonization and / or activation. Before and after the modification of the activated carbon, the activated carbon needs to be in a low-oxygen (for example, the oxygen volume content is less than 3%) or oxygen-free atmosphere to reduce or eliminate the generation of ineffective oxygen-containing functional groups.

[0052] In the present invention, to avoid the problem of burning or ignition of activated carbon during modification at high temperatures, the present invention intends to carry out modification treatment on activated carbon in a modification device by contacting it with an oxygen-containing gas for a certain duration at a certain wind speed in a temperature field lower than the lowest operating temperature, thereby adding effective oxygen-containing functional groups that can increase the denitrification rate on the activated carbon, improving the denitrification rate of the activated carbon, and avoiding surface burning or ignition of the activated carbon.

[0053] It should be noted that the modification device refers to a device (such as a belt furnace) that can heat up or cool down activated carbon to the modification temperature and enable the oxygen-containing gas to fully contact the activated carbon to reach the modification duration.

[0054] In the present invention, during the low-temperature modification process, since adjusting the modification parameters will affect the volatile content of activated carbon, unreasonable modification parameters may even cause burning or ignition of the activated carbon. And when it is necessary to meet the requirement of the volatile content of the modified activated carbon limited by the factory specifications, it is necessary to accurately control the modification parameters to produce products with both qualified volatile content and denitrification rate, which has practical modification significance. To accurately control the modification parameters, during the modification process, when the modification temperature, the flow rate of the oxygen-containing gas introduced, the wind speed, etc. are determined, it is necessary to reasonably control the modification duration, so as to add effective oxygen-containing functional groups that can increase the denitrification rate on the activated carbon within the limited range of increased volatile content. Through practical research, it has been found that under the given working conditions of the activated carbon feed state (including the total mass flow rate of the activated carbon, the initial volatile content of the activated carbon, the thickness of the activated carbon bedding, the bulk density of the activated carbon, the increase in the heat storage temperature of the activated carbon, the increase in the temperature of the activated carbon caused by the combustion of combustible gases in the initial volatile content of the activated carbon, the lowest operating temperature, etc.), the oxygen-containing gas inlet state (including the oxygen content of the oxygen-containing gas, the wind speed of the oxygen-containing gas, the introduction amount of the oxygen-containing gas, etc.) and the outlet state (including the volatile content of the modified activated carbon), a mathematical model for the modification duration required to reach the volatile content of the modified activated carbon has been established:

[0055]

[0056] In formula (1), t is the modification duration, h. w is the safety factor, with a value of 0.1 - 0.8. K is the fire safety index (it should be noted that when w = 100%, K = e, e is the fire safety threshold, equal to the K value when the surface of the activated carbon starts to catch fire, determined by the measured value. K is the measured value). m is the total mass flow rate of the activated carbon, kg / h. c is the oxygen content of the oxygen-containing gas, %. s is the wind speed of the oxygen-containing gas, m / s. h is the thickness of the activated carbon bedding, m. ρ is the bulk density of the activated carbon, kg / m 3 . Q is the oxygen demand flow rate for the modification of the activated carbon, m 3 / h. r is the modification reaction coefficient. f is the increase in the heat storage temperature of the activated carbon, °C. g is the increase in the temperature of the activated carbon caused by the combustion of combustible gases in the initial volatile matter of the activated carbon, °C. b is the modification temperature, °C. a is the lowest operating temperature, °C. n 1 is the ignition risk parameter, with a value ranging from 1 to 2. n 2 is the overspeed risk parameter, with a value ranging from 1.5 to 4. u is the safe wind speed, with a value ranging from 0.1 to 1.5 m / s. According to the mathematical model of the modification duration in Equation (1), high-quality modification of the activated carbon can be achieved under the given operating conditions of the activated carbon feeding state and the oxygen-containing gas inlet state, that is, increasing the proportion of effective oxygen-containing functional groups on the activated carbon as much as possible, thereby improving the denitrification rate of the activated carbon. It should be noted that when the parameters of the activated carbon feeding state or the oxygen-containing gas inlet state fluctuate, the optimal duration required for modification can also be obtained quickly and accurately, thereby improving production efficiency and avoiding increased production costs due to trial and error.

[0057] In the present invention, when oxidatively modifying the activated carbon, the amount of oxygen carried by the oxygen-containing gas is also closely related to the modification effect. Reasonably controlling the contact ratio between oxygen and the activated carbon per unit time helps to increase the formation of effective oxygen-containing functional groups. That is to say, within a unit time, based on the changes in parameters such as the feeding amount of the activated carbon, the initial volatile matter content of the activated carbon, and the agreed volatile matter content in the modified activated carbon, the total amount of oxygen carried by the oxygen-containing gas per unit time is adjusted in a timely manner. Through practice, it has been found that the total amount of oxygen carried by the oxygen-containing gas per unit time has the following relationship with the activated carbon state:

[0058] Q = m(f 2 - f 1 ) / [ρ o (1 - f 2 )] (2).

[0059] In Equation (2), Q is the oxygen demand flow rate for the modification of the activated carbon, m 3 / h. ρ o is the density of oxygen, kg / m 3 . m is the total mass flow rate of the activated carbon, kg / h. f 1 is the initial volatile matter of the activated carbon, %. f 2 is the target value of the volatile matter in the modified activated carbon, %. When the activated carbon state parameters fluctuate, the amount of oxygen introduced by the oxygen-containing gas per unit time under the current operating conditions can be calculated through Equation (2), thereby effectively promoting the formation of effective oxygen-containing functional groups. When the activated carbon state parameters remain unchanged, if the amount of oxygen introduced per unit time increases or decreases, it will reduce the proportion of effective oxygen-containing functional groups to a certain extent, thereby reducing the denitrification rate of the activated carbon.

[0060] It should be noted that in actual working conditions, the contact efficiency between activated carbon and oxygen hardly reaches a perfect ideal state. Generally speaking, in order to achieve just the right sufficient contact between activated carbon and oxygen, the amount of oxygen-containing gas actually introduced should be such that the total amount of oxygen it carries is in excess relative to the total theoretical amount of oxygen. According to practice, it is found that in actual working conditions, the amount of oxygen-containing gas introduced per unit time should satisfy the following relationship:

[0061] q = Q×r / c (3).

[0062] In formula (3), q is the flow rate of the oxygen-containing gas introduced, m 3 / h. Q is the oxygen demand flow rate for activated carbon modification, m 3 / h. r is the modification reaction coefficient. c is the oxygen content of the oxygen-containing gas, %. That is, under known working conditions, by adjusting the amount of oxygen-containing gas introduced per unit time through formula (3) to make the oxygen in excess relative to the theoretical amount to a given value, it should be noted that too low or too high an oxygen excess value is not conducive to the sufficient contact modification between activated carbon and oxygen.

[0063] In addition, the modification reaction coefficient r is closely related to the effective penetration height of the oxygen-containing gas in the activated carbon bed, and the two satisfy the following relationship:

[0064] r = j / c×(n 3 ^(100(h - h 0 )) + 100h 0 ) / (100h 0 ) (4).

[0065] In formula (4), j is the oxygen-containing gas excess correction coefficient, with a value of 0.1 - 2. h is the thickness of the activated carbon bedding, m. h 0 is the effective penetration height of the oxygen-containing gas in the activated carbon bed, 0.03 - 0.1m. n 3 is the effective penetration parameter, with a value of 1 - 10. That is to say, when the effective penetration height of the oxygen-containing gas in the activated carbon bed is different, the corresponding value of the modification reaction coefficient r will also change accordingly, thereby enabling precise adjustment of the excess amount of oxygen introduced, and thus promoting the formation of effective oxygen-containing functional groups.

[0066] It should be noted that all the formulas in the present invention are obtained by the inventor through fitting based on experiments and engineering applications. All calculations are based on the values after conversion according to the specified unit conversion. The values after converting the units are substituted into the formulas for calculation (after converting the units, only the values are substituted into the formulas for calculation, and the units are not substituted. The units are only used to adjust the magnitude of the values. It should be noted that in the present invention, "%" is not used as a unit symbol, and the conversion ratio needs to be considered during calculation. For example, when the oxygen content of the oxygen-containing gas is 21%, the actual calculation value during the calculation process should be 0.21. Similarly, other parameters with "%" are calculated with reference to this logic).

[0067] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0068] 1. Based on the feed state parameters of activated carbon and the inlet state parameters of oxygen-containing gas, etc., at a temperature lower than the lowest operating condition temperature, the present invention reasonably and precisely controls the modification duration of activated carbon and oxygen-containing gas under the current operating conditions, thereby being able to increase the effective oxygen-containing functional groups that can improve the denitrification rate of activated carbon while avoiding surface burning or ignition of activated carbon, and reducing the generation of ineffective oxygen-containing functional groups, achieving the purpose of improving the denitrification rate of activated carbon.

[0069] 2. The low-temperature modification method of activated carbon of the present invention is safe, controllable, easy to adjust, has a low input cost, good modification effect, is convenient for large-scale practical promotion and application, and has a broad market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a simplified flowchart showing the process of the modification method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The technical solutions of the present invention will be illustrated below. The scope of protection claimed by the present invention includes but is not limited to the following embodiments.

[0072] Example 1

[0073] A low-temperature modification method of activated carbon, the method comprising the following steps:

[0074] 1) Contact activated carbon with oxygen-containing gas at a temperature lower than the lowest operating condition temperature for a modification reaction to obtain modified activated carbon.

[0075] 2) Adjust the required modification duration at the current modification temperature according to the feed state of activated carbon, the inlet state of oxygen-containing gas, and the target value of the volatile matter content after modification of activated carbon.

[0076] Example 2

[0077] Repeat Example 1, except that in step 2), a mathematical model for the required modification duration at the current modification temperature is established with the feeding state of activated carbon, the inlet state of oxygen-containing gas, and the target value of the volatile matter content after the modification of activated carbon as variables. The mathematical model is as follows:

[0078]

[0079] In formula (1), t is the modification duration, h. w is the safety factor, with a value of 0.4. K is the ignition safety index. m is the total mass flow rate of activated carbon, kg / h. c is the oxygen content of the oxygen-containing gas, 21%. s is the wind speed of the oxygen-containing gas, m / s. h is the thickness of the activated carbon bedding, m. ρ is the bulk density of activated carbon, kg / m 3 . Q is the oxygen demand flow rate for the modification of activated carbon, m 3 / h. r is the modification reaction coefficient. f is the increase in the heat storage temperature of activated carbon, °C. g is the increase in the temperature of activated carbon caused by the combustion of combustible gases in the initial volatile matter of activated carbon, °C. b is the modification temperature, °C. a is the lowest operating temperature, °C. n 1 is the ignition risk parameter, with a value of 1.05. n 2 is the overspeed risk parameter, with a value of 2. u is the safety wind speed, with a value of 1 m / s.

[0080] Example 3

[0081] Repeat Example 2, except that under the current operating conditions, the oxygen input flow rate of the oxygen-containing gas is controlled according to the requirements of the volatile matter content after the modification of activated carbon; then:

[0082] Q = m(f 2 - f 1 ) / [ρ o (1 - f 2 )] (2).

[0083] In formula (2), Q is the oxygen demand flow rate for the modification of activated carbon, m 3 / h. ρ o is the density of oxygen, kg / m 3 . m is the total mass flow rate of activated carbon, kg / h. f 1 is the initial volatile matter content of activated carbon, %. f 2 is the target value of the volatile matter content after the modification of activated carbon, %.

[0084] Example 4

[0085] Repeat Example 3, except that under the current operating conditions, the flow rate of the oxygen-containing gas is controlled according to the excess oxygen flow rate required in the modification reaction, so as to meet the requirements for the modification of activated carbon. Then:

[0086] q = Q × r / c (3).

[0087] In formula (3), q is the flow rate of the oxygen-containing gas introduced, m 3 / h. Q is the oxygen demand flow rate for activated carbon modification, m 3 / h. r is the modification reaction coefficient. c is the oxygen content of the oxygen-containing gas, 21%.

[0088] Example 5

[0089] Repeat Example 4, except that under the current operating conditions, the magnitude of the modification reaction coefficient is deduced based on the effective penetration height of the oxygen-containing gas in the activated carbon bed layer, then:

[0090] r = j / c × (n 3 ^(100(h - h 0 )) + 100h 0 ) / (100h 0 ) (4).

[0091] In formula (4), j is the excess oxygen-containing gas correction coefficient, with a value of 0.5. h is the thickness of the activated carbon bedding, m. h 0 is the effective penetration height of the oxygen-containing gas in the activated carbon bed layer, with a value of 0.07 m. n 3 is the effective penetration parameter, with a value of 8.

[0092] Example 6

[0093] Repeat Example 5, except that in step 1), the temperature below the lowest operating condition temperature is 300 °C.

[0094] Example 7

[0095] Repeat Example 6, except that in step 1), the temperature below the lowest operating condition temperature is 330 °C.

[0096] Example 8

[0097] Repeat Example 7, except that in step 1), the temperature below the lowest operating condition temperature is 340 °C.

[0098] Example 9

[0099] Repeat Example 8, except that during the modification process, the maximum bedding thickness of the activated carbon is 0.05 m.

[0100] Example 10

[0101] Repeat Example 9, except that during the modification process, the maximum bedding thickness of the activated carbon is 0.1 m.

[0102] Example 11

[0103] Repeat Example 10, except that the oxygen content in the oxygen-containing gas is 22%.

[0104] Example 12

[0105] Repeat Example 10, except that the oxygen-containing gas consists of oxygen and air.

[0106] Example 13

[0107] Repeat Example 12, except that the activated carbon is carbonized activated carbon. Before and after the modification of the activated carbon, the activated carbon needs to be in a low-oxygen atmosphere.

[0108] Application Example 1

[0109] Under a nitrogen atmosphere, the carbonized hot activated carbon is transported into the reaction furnace. The total mass flow rate m of the activated carbon entering the furnace is 1000 kg / h, the laying thickness h of the activated carbon is 0.06 m, and the bulk density ρ of the activated carbon is 600 kg / m 3 ; After detection, the increase value f of the heat storage temperature of the activated carbon is about 0.2 °C, and the increase value g of the temperature of the activated carbon caused by the combustion of the combustible gas in the initial volatile matter of the activated carbon is about 3 °C. The initial volatile matter f of the activated carbon 1 is 2.9%, and the lowest operating temperature a is 345 °C; when the temperature of the hot activated carbon drops to the modification temperature b = 340 °C, maintain this temperature and introduce an oxygen-containing gas composed of air and oxygen. After detection, the oxygen content c of the oxygen-containing gas is 21%, the wind speed s of the oxygen-containing gas is 0.9 m / s, and the effective penetration height h of the oxygen-containing gas in the activated carbon bed 0 is 0.07 m; the density of oxygen is 1.429 kg / m 3 .

[0110] Under the current operating conditions, set the target value f of the volatile matter after the modification of the activated carbon required currently 2 to be at most 5% (the allowable downward fluctuation value is 0.2), the safety factor w is 0.63, the ignition safety index K is 8.50, the ignition sub-risk parameter n 1 is 1.05, the overspeed risk parameter n 2 is 2, the safety wind speed u is 1 m / s, and the effective penetration parameter n 3 takes a value of 8; the oxygen-containing gas excess correction coefficient j takes a value of 0.5; then first use formula (2) and formula (4) to calculate the oxygen input flow rate Q and the modification reaction coefficient r of the oxygen-containing gas respectively:

[0111] Q = m(f 2 - f 1 ) / [ρ o (1 - f 2 )] ≈ 15.47

[0112] r = j / c × (n 3 ^(100(h - h 0)) + 100h 0 ) / (100h 0 ) ≈ 2.42

[0113] That is, under the current working conditions, the oxygen input flow rate Q of the oxygen-containing gas is 15.47 m 3 / h, and the modification reaction coefficient r is 2.42; then, according to the calculated Q value and r value, the actual input flow rate q (m 3 / h) of the oxygen-containing gas is calculated using formula (3):

[0114] q = Q × r / c ≈ 178.27

[0115] That is, under the current working conditions, the actual input flow rate q of the oxygen-containing gas should be 178.27 m 3 / h. Finally, the modification duration t of the activated carbon under the current working conditions is calculated using formula (1):

[0116]

[0117] That is, under the current working conditions, after the activated carbon is modified with the oxygen-containing gas for 0.75 h, the input of the oxygen-containing gas is stopped and nitrogen is input at the same time. After the activated carbon is cooled to room temperature, the modified activated carbon is obtained. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 64.38%, and the volatile matter f 2 The measured value is approximately 4.97%.

[0118] Application Example 2

[0119] Repeat Application Example 1, except that the modification temperature is 320 °C. At this temperature, the corresponding ignition safety index K is 13.15, and the calculated modification duration t of the activated carbon under the current working conditions should be 1.09 h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 63.24%, and the volatile matter f 2 The measured value is approximately 4.95%.

[0120] Application Example 3

[0121] Repeat Application Example 1, except that the modification temperature is 320 °C. At this temperature, the corresponding ignition safety index K is 18.10, and the calculated modification duration t of the activated carbon under the current working conditions should be 1.41 h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 62.15%, and the volatile matter f 2 The measured value is approximately 4.92%.

[0122] Application Example 4,

[0123] Repeat Application Example 1, except that the modification duration is directly adjusted to 1 h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 65.03%, and the volatile matter f2 The measured value is approximately 6.25%.

[0124] Application Example 5

[0125] Repeat Application Example 1, only directly adjusting the duration of the modification treatment to 0.6 h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 63.61%, and the volatile matter f 2 The measured value is approximately 4.62%.

[0126] Application Example 6

[0127] Repeat Application Example 1, only directly adjusting the input amount of the oxygen-containing gas during the modification treatment to 190 m 3 / h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 64.89%, and the volatile matter f 2 The measured value is approximately 5.54%.

[0128] Application Example 7

[0129] Repeat Application Example 1, only directly adjusting the input amount of the oxygen-containing gas during the modification treatment to 160 m 3 / h. The denitrification rate of the modified activated carbon obtained under the current working conditions is detected to be approximately 63.73%, and the volatile matter f 2 The measured value is approximately 4.55%.

[0130] Comparative Example 1

[0131] The carbonized hot activated carbon is sent into a Slp activation furnace and activated by a traditional activation process to obtain traditional finished activated carbon. The denitrification rate of the activated carbon obtained under the current working conditions is detected to be approximately 60.20%, and the volatile matter f 2 The measured value is approximately 2.90%.

Claims

1. A method for low-temperature modification of activated carbon, characterized in that: The method comprises the following steps: 1) contacting the activated carbon with an oxygen-containing gas at a temperature lower than the minimum operating temperature to perform a modification reaction to obtain modified activated carbon; 2) According to the feed state of activated carbon, the intake state of oxygen-containing gas and the target value of the volatile matter after the activated carbon modification, the modification time required at the current modification temperature is adjusted.

2. The method according to claim 1, characterized in that: In step 2), a mathematical model for the required modification time at the current modification temperature is established with the feed state of activated carbon, the intake state of oxygen-containing gas and the target value of the volatile matter after the modified activated carbon as variables. The mathematical model is as follows: In formula (1), t is the modification time, h; w is the safety factor, which is 0.1-0.8; K is the fire safety index; m is the total mass flow rate of activated carbon, kg / h; c is the oxygen content of the oxygen-containing gas, %; s is the wind speed of the oxygen-containing gas, m / s; h is the thickness of the activated carbon layer, m; ρ is the bulk density of the activated carbon, kg / m 3 ; Q is the oxygen demand flow rate of activated carbon modification, m 3 / h; r is the modification reaction coefficient; f is the temperature rise of activated carbon, ℃; g is the temperature rise of activated carbon after the combustible gas in the initial volatile matter of activated carbon is burned, ℃; b is the modification temperature, ℃; a is the minimum operating temperature, ℃; n1 is the ignition risk parameter, with a value of 1 to 2; n2 is the overspeed risk parameter, with a value of 1.5 to 4; u is the safe wind speed, which ranges from 0.1 to 1.5 m / s.

3. The method according to claim 2, characterized in that: Under the current working conditions, according to the requirements of the volatile matter after the activated carbon modification, the oxygen-containing gas flow rate is controlled; then: Q=m(f2-f1) / [ρ o (1-f2)] (2); In formula (2), Q is the oxygen demand flow rate of activated carbon modification, m 3 / h;ρ o is the density of oxygen, kg / m 3 ; m is the total mass flow rate of activated carbon, kg / h; f1 is the initial volatile matter of activated carbon, %; f2 is the target value of volatile matter after modified activated carbon, %.

4. The method according to claim 2 or 3, characterized in that: Under the current working conditions, according to the required excess flow of oxygen in the modification reaction, the flow rate of oxygen-containing gas is controlled to meet the requirements of activated carbon modification; then: q = Q × r / c (3); In formula (3), q is the flow rate of oxygen-containing gas, m is 3 / h; Q is the oxygen demand flow rate of activated carbon modification, m 3 / h; r is the modification reaction coefficient; c is the oxygen content of the oxygen-containing gas, %.

5. The method according to any one of claims 2 to 4, characterized in that: Under the current working conditions, the size of the modification reaction coefficient is calculated based on the effective penetration height of the oxygen-containing gas in the activated carbon layer, and then: r=j / c×(n3^(100(h-h0))+100h0) / (100h0) (4); In formula (4), j is the oxygen-containing gas excess correction coefficient, which takes a value of 0.1 to 2; h is the activated carbon layer thickness, m; h0 is the effective penetration height of the oxygen-containing gas in the activated carbon layer, which takes a value of 0.03 to 0.1 m, h0 ≥ h; n3 is the effective penetration parameter, which takes a value of 1 to 10.

6. The method according to any one of claims 1 to 5, characterized in that: In step 1), the minimum operating temperature is not higher than 350°C, preferably 240-345°C, and more preferably 280-335°C.

7. The method according to any one of claims 1 to 6, characterized in that: During the modification process, the maximum thickness of the activated carbon does not exceed 0.25 m, preferably 0.03 to 0.15 m, and more preferably 0.05 to 0.1 m.

8. The method according to any one of claims 1 to 7, characterized in that: During the modification process, the volume content of oxygen in the oxygen-containing gas is not less than 3%, preferably 5-21%.

9. The method according to claim 8, characterized in that: The oxygen-containing gas is composed of oxygen and one or more of air, nitrogen, carbon dioxide and inert gas.

10. The method according to any one of claims 1 to 9, characterized in that: The activated carbon is carbonized activated carbon and / or activated activated carbon, preferably carbonized and / or activated hot activated carbon; before and after the activated carbon is modified, the activated carbon needs to be in a low-oxygen or anaerobic atmosphere.

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