CN117943132A - In-situ regeneration method of carbon-based catalyst - Google Patents

In-situ regeneration method of carbon-based catalyst Download PDF

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Publication number
CN117943132A
CN117943132A CN202410347003.6A CN202410347003A CN117943132A CN 117943132 A CN117943132 A CN 117943132A CN 202410347003 A CN202410347003 A CN 202410347003A CN 117943132 A CN117943132 A CN 117943132A
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carbon
based catalyst
reaction tower
liquid
layer
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CN117943132B (en
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朱荣
高强生
曹卫东
刘春红
何金昌
卓佐西
王光宇
徐颜军
田庆丰
牛生越
董莹
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Ili Xintian Coal Chemical Co ltd
Zhejiang Baimahu Laboratory Co ltd
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Ili Xintian Coal Chemical Co ltd
Zhejiang Baimahu Laboratory Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/48—Liquid treating or treating in liquid phase, e.g. dissolved or suspended
    • B01J38/70—Wet oxidation of material submerged in liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/20—Regeneration or reactivation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/02—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/14—Maintenance of water treatment installations
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Catalysts (AREA)

Abstract

The invention relates to the technical field of catalyst regeneration, and discloses a carbon-based catalyst in-situ regeneration method, which comprises the following steps: (1) Introducing backwash liquid containing persulfate into a reaction tower with a carbon-based catalyst layer from the bottom of the tower; (2) In the reaction tower, the reverse washing liquid flows from bottom to top at a flow rate of not higher than 7 m/h, flows through the heat insulation ball layer, then enters the heating layer for heating, and flows into the carbon-based catalyst layer attached above the heating layer for oxidizing organic pollutants; or firstly flows through the heat insulation sphere layer and then enters the carbon-based catalyst layer to heat and oxidize organic pollutants; (3) The reverse washing liquid flows out from the upper part of the reaction tower and then is introduced from the bottom of the reaction tower; (4) circularly carrying out the steps (2) - (3). By adopting the method provided by the invention, the organic pollutants attached to the carbon-based catalyst can be effectively removed, the activity of the carbon-based catalyst can be recovered to a large extent, and the in-situ regeneration of the carbon-based catalyst in the reaction tower can be realized.

Description

In-situ regeneration method of carbon-based catalyst
Technical Field
The invention relates to the technical field of catalyst regeneration, in particular to an in-situ regeneration method of a carbon-based catalyst.
Background
With the rapid development of economy and society, the discharge amount of industrial wastewater is greatly increased, and the wastewater has various toxic and harmful substances, especially wastewater in the fields of chemical industry, printing and dyeing, pharmacy and the like, contains high-concentration organic pollutants, and contains Persistent Organic Pollutants (POPs) such as perfluorooctane, polycyclic aromatic hydrocarbon, hexachlorobenzene, hexabromobiphenyl, sulfonic acid and the like, which is the difficulty of current wastewater treatment.
Advanced oxidation techniques based on carbon-based catalysts (such as activated carbon) have been a hot spot of research in the field of water treatment in recent years. However, during the operation of the carbon-based catalyst, suspended organic matters (SSI) contained in raw water gradually adhere to the surface of the catalyst; because of the strong adsorption effect of the carbon-based carrier, the adsorption rate is always greater than the catalytic oxidative degradation rate (v Adsorption of >v Oxidative degradation of ), which causes the organic pollutant molecules to continuously accumulate in the internal pore canal of the catalyst carrier, so that the accessibility of the active center of the catalyst is weakened, and the catalytic oxidative performance is reduced, namely the catalyst shows the deactivation behavior.
After the carbon-based catalyst is used for a period of time, in order to recover the catalytic oxidation performance, various contaminants trapped on the surface are removed by water backwashing and air scrubbing methods, but it is difficult to remove the contaminants adsorbed in the micropores of the carbon-based catalyst. The high-temperature heating regeneration method (for example, patent CN 202210144384.9) can carbonize the organic pollutants attached to the catalyst to recover part of the activity of the catalyst, but needs to heat the catalyst to a high temperature of 700-850 ℃ to carbonize the organic pollutants, so that a special regeneration furnace is needed, the catalyst needs to be dug out from the reaction tower to be refilled in the regeneration process, in-situ regeneration in the reaction tower cannot be realized, in addition, the high-temperature heating regeneration method can influence the pore channel structure of the carbon-based catalyst, and generally only can recover the activity of the carbon-based catalyst to about 60% of that of the new material.
Disclosure of Invention
In order to solve the technical problems that the existing carbon-based catalyst regeneration method cannot realize in-situ regeneration in a reaction tower and has limited regeneration effect, the invention provides a carbon-based catalyst in-situ regeneration method. By adopting the method, the organic pollutants attached to the carbon-based catalyst can be effectively removed, the activity of the carbon-based catalyst is recovered to a large extent, and the in-situ regeneration of the carbon-based catalyst in the reaction tower can be realized.
The specific technical scheme of the invention is as follows:
in a first aspect, the present invention provides a method for in situ regeneration of a carbon-based catalyst, comprising the steps of:
(1) Introducing backwash liquid containing persulfate into a reaction tower with a carbon-based catalyst layer from the bottom of the tower, wherein the carbon-based catalyst layer is filled with deactivated carbon-based catalyst;
(2) In the reaction tower, the reverse washing liquid flows from bottom to top at a flow rate of not higher than 7 m/h, and the catalyst regeneration is carried out in the following way one or the other way:
Mode one: the reverse washing liquid flows through the heat insulation ball layer, then enters the heating layer for heating, and then flows into organic pollutants attached to the carbon-based catalyst in the carbon-based catalyst layer attached to the upper part of the heating layer;
Mode two: the reverse washing liquid firstly flows through the heat insulation sphere layer and then enters the carbon-based catalyst layer to heat and oxidize organic pollutants attached to the carbon-based catalyst;
(3) The reverse washing liquid flows out from the upper part of the reaction tower and then is introduced from the bottom of the reaction tower;
(4) And (5) circularly carrying out the steps (2) - (3).
The invention adopts persulfate as oxidant, because the active site in the deactivated carbon-based catalyst is covered by organic pollutant, SO that the capacity of activating persulfate is lost or greatly weakened, SO the invention adopts a thermal activation mode (namely, in the step (2), the backwashing liquid is heated in a heating layer or a carbon-based catalyst layer), and sulfate radical (SO 4 -) is generated by the activation of persulfate. Compared with hydroxyl radical (. OH), the sulfate radical has higher oxidation-reduction potential and longer half-life (SO 4 -. Half-life is 30-40 mu s), SO that organic pollutants attached to the carbon-based catalyst can be better oxidized, and the activity of the carbon-based catalyst is recovered; in addition, the oxidizing power of sulfate radicals is non-selective and can degrade most of the organic matter.
In the invention, backwash liquid flows through the heat-insulating ball layer and then flows into the carbon-based catalyst layer, and in the heat-insulating ball layer, the ball body can disturb backwash liquid, so that the flow direction of backwash liquid is changed, the path of persulfate and free radicals generated by persulfate in the carbon-based catalyst layer is prolonged, the sufficient contact of sulfate radicals and the carbon-based catalyst is facilitated, and organic pollutants attached in the catalyst are degraded. And the backwash liquid heats up again when entering the heating layer (in the first mode) or the carbon-based catalyst layer (in the second mode), and the heat-insulating ball layer is utilized to block the heat in the heating layer and the carbon-based catalyst layer from being conducted downwards to a certain extent, so that persulfate can be accelerated and activated to generate sulfate radical after reaching the heating layer or the carbon-based catalyst layer, thereby being beneficial to enabling the sulfate radical to be in contact with the carbon-based catalyst quickly after being generated, reducing the attenuation of the radical before playing a role, and further improving the regeneration effect of the catalyst.
In addition, the flow rate of the back washing liquid in the reaction tower is controlled to be 7 m/h or less, so that the persulfate and the heating layer (in the first mode) or the carbon-based catalyst layer (in the second mode) can be contacted for a sufficient time, and the persulfate can be fully activated to generate more sulfate radicals, thereby realizing a better regeneration effect of the carbon-based catalyst.
Based on the above effects, the invention can obtain better catalyst regeneration effect and recover the activity of the carbon-based catalyst to a greater extent; in addition, the temperature required for activating the persulfate is low, and a regeneration furnace with high heat resistance is not required, so that when the carbon-based catalyst is regenerated, the carbon-based catalyst is not required to be transferred to other devices such as the regeneration furnace and the like, and in-situ regeneration can be realized in the reaction tower, thereby reducing the load and unload workload of regeneration and reducing the energy consumption.
Preferably, in the step (2), the temperature of the backwash liquid after passing through the carbon-based catalyst layer is 70-80 ℃.
Preferably, in the step (1), the backwash liquid is preheated to 35-40 ℃ before being introduced into the reaction tower.
By preheating the backwash liquid, the backwash liquid can be heated to a required temperature in the heating layer (in the first mode) or the carbon-based catalyst layer (in the second mode), so that more sulfate radicals are generated, and organic pollutants attached to the carbon-based catalyst are removed by oxidation to a greater extent.
Preferably, in the step (2), the heat-insulating ball layer is formed by mixing heat-insulating balls with diameters of 3-5 mm and 8-12 mm respectively.
The heat insulation balls with the two diameters are mixed, so that the heat insulation effect of the heat insulation ball layer is improved, the disturbance effect of the heat insulation ball layer on backwash liquid is improved, and the regeneration effect of the carbon-based catalyst is improved.
Further, the mass ratio of the heat insulation balls with the diameters of 3-5 mm and 8-12 mm is 1:3-6.
Preferably, in the step (2), the thickness of the thermal insulation ball layer is 4-10 cm.
Preferably, in the step (2), the thermal conductivity of the thermal insulation balls in the thermal insulation ball layer is 0.01 to 0.06W/(m·k).
Preferably, after the step (4), evacuating the liquid in the reaction tower, and then changing the backwashing liquid in the steps (1) to (4) into pure water, and washing the carbon-based catalyst according to the steps (1) to (4).
Further, after the water washing is completed, the liquid in the reaction tower is emptied, hot air is blown into the reaction tower, and the carbon-based catalyst is purged until no obvious white steam exists in the outlet air at the top of the reaction tower.
The carbon-based catalyst can be dehumidified and dried by blowing hot air, and impurities remained in the pore channels of the carbon-based catalyst are carried out by utilizing water vapor.
Further, the temperature of the hot air is 70-80 ℃.
Preferably, in the step (4), the times of performing the steps (2) - (3) are 3-5 times.
Preferably, in the step (1), the concentration of the persulfate in the backwash liquid is 0.05-0.3 mol/L.
Preferably, before step (1), the vent valve at the top of the reaction column is opened.
In the process of oxidizing organic pollutants by utilizing persulfate, CO 2 is generated by reaction and can be discharged through an exhaust valve at the top of the reaction tower.
In a second aspect, the present invention provides an apparatus for use in the carbon-based catalyst in situ regeneration process, comprising a reaction tower and a backwash water tank; the bottom liquid inlet in the reaction tower is connected with the liquid outlet in the backwashing water tank, and the upper liquid outlet in the reaction tower is connected with the liquid inlet in the backwashing water tank; a carbon-based catalyst layer is arranged in the reaction tower, and a heat insulation ball layer is arranged below the carbon-based catalyst layer; a heating layer attached to the lower portion of the carbon-based catalyst layer is arranged between the carbon-based catalyst layer and the heat insulation ball layer, or a heating pipe is arranged in the carbon-based catalyst layer.
Preferably, a backwash water tank heat exchanger is arranged in the backwash water tank.
Preferably, the top of the reaction tower is provided with an exhaust port.
Preferably, the device further comprises a fan connected with the lower air inlet in the reaction tower; an air heat exchanger is arranged between the fan and an air inlet at the lower part of the reaction tower.
Compared with the prior art, the invention has the following advantages:
(1) The invention adopts persulfate oxidant to remove the organic pollutant attached to the carbon-based catalyst, can realize the in-situ regeneration of the carbon-based catalyst in the reaction tower, does not need to load and unload the catalyst, and can reduce the energy consumption in the catalyst regeneration process.
(2) The invention adopts the mode that the reverse washing liquid flows through the heat insulation ball layer and then flows into the carbon-based catalyst layer, and the temperature is raised in the heating layer between the heat insulation ball layer and the carbon-based catalyst layer or in the carbon-based catalyst layer, so that the sulfate radical can fully play the role of the sulfate radical, and the activity of the carbon-based catalyst is recovered to a greater extent.
(3) According to the invention, backwash liquid is preheated before cyclic backwash is carried out, and two heat-insulating balls with different diameters are mixed in the heat-insulating ball layer, so that the oxidation removal of organic pollutants attached to the carbon-based catalyst to a greater extent is facilitated, and the regeneration effect of the carbon-based catalyst is improved.
Drawings
FIG. 1 is a schematic diagram of a construction of an apparatus for wastewater treatment and carbon-based catalyst regeneration according to the present invention.
The reference numerals are: the reaction tower 1, a tower bottom liquid inlet 1-1, an upper liquid outlet 1-2, an exhaust port 1-3, a lower air inlet 1-4, a tower bottom liquid outlet 1-5, a backwash water tank 2, a liquid inlet 2-1, a liquid outlet 2-2, a heating pipe 3, a backwash water tank heat exchanger 4, a fan 5, an air heat exchanger 6, a liquid outlet valve 7, an exhaust valve 8 and a backwash water pump 9.
Detailed Description
The invention is further described below with reference to examples.
An in situ regeneration method of a carbon-based catalyst, comprising the following steps:
(1) Introducing backwash liquid containing persulfate into a reaction tower with a carbon-based catalyst layer from the bottom of the tower, wherein the carbon-based catalyst layer is filled with deactivated carbon-based catalyst;
(2) In the reaction tower, the reverse washing liquid flows from bottom to top at a flow rate of not higher than 7 m/h, and the catalyst regeneration is carried out in the following way one or the other way:
Mode one: the reverse washing liquid flows through the heat insulation ball layer, then enters the heating layer for heating, and then flows into organic pollutants attached to the carbon-based catalyst in the carbon-based catalyst layer attached to the upper part of the heating layer;
Mode two: the reverse washing liquid firstly flows through the heat insulation sphere layer and then enters the carbon-based catalyst layer to heat and oxidize organic pollutants attached to the carbon-based catalyst;
(3) The reverse washing liquid flows out from the upper part of the reaction tower and then is introduced from the bottom of the reaction tower;
(4) And (5) circularly carrying out the steps (2) - (3).
As a specific embodiment, before step (1), the vent valve at the top of the reaction column is opened.
In step (1), the concentration of persulfate in the backwash liquid is 0.05-0.3 mol/L.
In the step (1), before the backwash liquid is introduced into a reaction tower, preheating the backwash liquid to 35-40 ℃; in the step (2), the temperature of the backwash liquid after passing through the carbon-based catalyst layer is 70-80 ℃.
In the step (2), the thickness of the heat-insulating ball layer is 4-10 cm, the heat-insulating ball layer is formed by mixing heat-insulating balls with the diameters of 3-5 mm and 8-12 mm in a mass ratio of 1:3-6, and the heat conductivity coefficient of the heat-insulating balls is 0.01-0.06W/(m.K).
In the step (4), the times of circularly carrying out the steps (2) - (3) are 3-5 times.
As a specific implementation mode, after the step (4), evacuating the liquid in the reaction tower, changing the backwashing liquid in the steps (1) - (4) into pure water, and washing the carbon-based catalyst according to the steps (1) - (4); and then evacuating the liquid in the reaction tower, blowing hot air at 70-80 ℃ into the reaction tower, and blowing the carbon-based catalyst until no obvious white steam exists in the outlet air at the top of the reaction tower.
The equipment used in the carbon-based catalyst in-situ regeneration method comprises a reaction tower 1 and a backwashing water tank 2; the bottom liquid inlet 1-1 in the reaction tower 1 is connected with the liquid outlet 2-2 in the backwashing water tank 2, and the upper liquid outlet 1-2 in the reaction tower 1 is connected with the liquid inlet 2-1 in the backwashing water tank 2; a carbon-based catalyst layer is arranged in the reaction tower 1, and a heat insulation ball layer is arranged below the carbon-based catalyst layer; a heating layer attached to the lower portion of the carbon-based catalyst layer is arranged between the carbon-based catalyst layer and the heat insulation ball layer, or a heating pipe 3 is arranged in the carbon-based catalyst layer.
Preferably, a backwash water tank heat exchanger 4 is provided in the backwash water tank 2.
Preferably, the top of the reaction tower 1 is provided with an exhaust port 1-3.
Preferably, the device also comprises a fan 5 connected with the lower air inlets 1-4 in the reaction tower 1; an air heat exchanger 6 is arranged between the fan 5 and the air inlet 1-4 at the lower part of the reaction tower 1.
Example 1
The wastewater treatment and carbon-based catalyst regeneration apparatus used in this example is shown in fig. 1 (the carbon-based catalyst and the heat insulation balls are not filled in fig. 1), and the specific structure is as follows: comprises a reaction tower 1, a backwashing water tank 2 and a fan 5. The reaction tower 1 is provided with a tower bottom liquid inlet 1-1, an upper liquid outlet 1-2, an exhaust port 1-3, a lower air inlet 1-4 and a tower bottom liquid outlet 1-5; a liquid discharge valve 7 is arranged on the liquid discharge port 1-5 at the bottom of the tower; the exhaust ports 1-3 are positioned at the top of the tower and are provided with exhaust valves 8. The backwash water tank 2 is provided with a liquid inlet 2-1, a liquid outlet 2-2 and a backwash water tank heat exchanger 4. The liquid inlet 1-1 at the bottom of the tower is connected with the liquid outlet 2-2, and a backwash water pump 9 is arranged between the liquid inlet and the liquid outlet; the upper liquid outlet 1-2 is connected with the liquid inlet 2-1. The air outlet of the fan 5 is connected with the lower air inlets 1-4, and an air heat exchanger 6 is arranged between the air outlet and the lower air inlet. A carbon-based catalyst layer, a heating layer and a heat insulation ball layer are sequentially arranged in the reaction tower 1 from top to bottom, and the carbon-based catalyst layer is attached to the heating layer from top to bottom; a heating pipe 3 is arranged in the heating layer; the thickness of the heat insulation ball layer is 6 cm, and the heat insulation balls with diameters of 5mm and 10 mm (the heat conductivity coefficient is 0.03W/(m.K)) are mixed according to the mass ratio of 1:4; the carbon-based catalyst used in this example was activated carbon.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 86.2% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 41.5%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 7 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 75.8%. The activation rate was calculated to be 87.9% according to the COD removal rate of the carbon-based catalyst at the time of initial use and after regeneration.
Example 2
The wastewater treatment and carbon-based catalyst regeneration apparatus used in this example is shown in fig. 1 (the carbon-based catalyst and the heat insulation balls are not filled in fig. 1), and the specific structure is as follows: comprises a reaction tower 1, a backwashing water tank 2 and a fan 5. The reaction tower 1 is provided with a tower bottom liquid inlet 1-1, an upper liquid outlet 1-2, an exhaust port 1-3, a lower air inlet 1-4 and a tower bottom liquid outlet 1-5; a liquid discharge valve 7 is arranged on the liquid discharge port 1-5 at the bottom of the tower; the exhaust ports 1-3 are positioned at the top of the tower and are provided with exhaust valves 8. The backwash water tank 2 is provided with a liquid inlet 2-1, a liquid outlet 2-2 and a backwash water tank heat exchanger 4. The liquid inlet 1-1 at the bottom of the tower is connected with the liquid outlet 2-2, and a backwash water pump 9 is arranged between the liquid inlet and the liquid outlet; the upper liquid outlet 1-2 is connected with the liquid inlet 2-1. The air outlet of the fan 5 is connected with the lower air inlets 1-4, and an air heat exchanger 6 is arranged between the air outlet and the lower air inlet. A carbon-based catalyst layer, a heating layer and a heat insulation ball layer are sequentially arranged in the reaction tower 1 from top to bottom, and the carbon-based catalyst layer is attached to the heating layer from top to bottom; a heating pipe 3 is arranged in the heating layer; the thickness of the heat insulation ball layer is 10 cm, and the heat insulation balls with diameters of 5mm and 12 mm (the heat conductivity coefficient is 0.03W/(m.K)) are mixed according to the mass ratio of 1:5; the carbon-based catalyst used in this example was activated carbon.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 83.6% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 47.1%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting sodium persulfate solution with the concentration of 15 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow speed of 5 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 71.0%. The activation rate was calculated to be 84.9% according to the removal rate of COD at the time of the initial use and after regeneration of the carbon-based catalyst.
Example 3
The wastewater treatment and carbon-based catalyst regeneration apparatus used in this example is shown in fig. 1 (the carbon-based catalyst and the heat insulation balls are not filled in fig. 1), and the specific structure is as follows: comprises a reaction tower 1, a backwashing water tank 2 and a fan 5. The reaction tower 1 is provided with a tower bottom liquid inlet 1-1, an upper liquid outlet 1-2, an exhaust port 1-3, a lower air inlet 1-4 and a tower bottom liquid outlet 1-5; a liquid discharge valve 7 is arranged on the liquid discharge port 1-5 at the bottom of the tower; the exhaust ports 1-3 are positioned at the top of the tower and are provided with exhaust valves 8. The backwash water tank 2 is provided with a liquid inlet 2-1, a liquid outlet 2-2 and a backwash water tank heat exchanger 4. The liquid inlet 1-1 at the bottom of the tower is connected with the liquid outlet 2-2, and a backwash water pump 9 is arranged between the liquid inlet and the liquid outlet; the upper liquid outlet 1-2 is connected with the liquid inlet 2-1. The air outlet of the fan 5 is connected with the lower air inlets 1-4, and an air heat exchanger 6 is arranged between the air outlet and the lower air inlet. A carbon-based catalyst layer and a heat insulation ball layer positioned below the carbon-based catalyst layer are arranged in the reaction tower 1; a heating pipe 3 is arranged in the carbon-based catalyst layer; the thickness of the heat insulation ball layer is 4 cm, and the heat insulation balls with diameters of 3mm and 8mm (the heat conductivity coefficient is 0.03W/(m.K)) are mixed according to the mass ratio of 1:3; the carbon-based catalyst used in this example was activated carbon.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 87.7% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 50.9%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 70 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 35 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow speed of 4 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 3 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the removal rate of COD was measured to be 77.3%. The activation rate was calculated to be 88.1% according to the COD removal rate of the carbon-based catalyst at the time of initial use and after regeneration.
Comparative example 1
The wastewater treatment and carbon-based catalyst regeneration apparatus structure employed in this comparative example was different from that of example 1 only in that: the heat insulation ball layer is not arranged, and the heating layer is arranged on the inner wall of the shell of the reaction tower 1.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 76.2% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 40.3%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 7 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the removal rate of COD was measured to be 55.3%. The activation rate was calculated to be 72.6% according to the removal rate of COD after the initial use and regeneration of the carbon-based catalyst.
Comparative example 2
The wastewater treatment and carbon-based catalyst regeneration apparatus structure employed in this comparative example was different from that of example 1 only in that: the heat-insulating balls were replaced with ceramic balls having a thermal conductivity of 2.0W/(m.K).
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 80.6% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 42.9%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 7 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 62.4%. The activation rate was calculated to be 77.4% according to the COD removal rate of the carbon-based catalyst at the time of initial use and after regeneration.
Data analysis and conclusion:
(1) The significantly lower activation rate after regeneration of comparative example 2 compared to example 1 indicates that the carbon-based catalyst regeneration effect can be improved by using the heat insulating balls. The heat-insulating ball layer can prevent heat in the heating layer from being conducted downwards to a certain extent, so that persulfate is accelerated to be activated to generate sulfate radical after reaching the heating layer or the carbon-based catalyst layer, and the heat-insulating ball layer is beneficial to enabling the sulfate radical to be in contact with the carbon-based catalyst rapidly after being generated, and reducing the attenuation of the radical before the radical acts.
(2) The higher activation rate after regeneration of comparative example 2 compared to comparative example 1 shows that the regeneration effect of the carbon-based catalyst can be improved by providing the sphere layer in the reaction column. The ball body can disturb backwash liquid, change the flow direction of backwash liquid, further prolong the path of persulfate and free radical generated by persulfate in the carbon-based catalyst layer, and be favorable for the sufficient contact of sulfate radical and carbon-based catalyst, and further degrade organic pollutants attached in the catalyst.
Comparative example 3
The wastewater treatment and carbon-based catalyst regeneration apparatus used in this comparative example were the same as those used in example 1.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was found to be 87.0% when the carbon-based catalyst was first used.
The equipment is continuously operated, and after the COD removal rate is reduced to 45.2%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 12 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 68.8%. The activation rate was calculated to be 79.1% according to the removal rate of COD after the initial use and regeneration of the carbon-based catalyst.
Data analysis and conclusion: the significantly lower activation rate after regeneration of comparative example 3 compared to example 1 indicates that the regeneration effect of the carbon-based catalyst is adversely affected when the flow rate of the sodium persulfate solution in the reaction tower is too high. This is because, when the flow rate is too high, the contact time of sodium persulfate with the heating layer is too short to be sufficiently activated to generate more sulfate radicals.
Comparative example 4
The wastewater treatment and carbon-based catalyst regeneration apparatus structure employed in this comparative example was different from that of example 1 only in that: the backwash water tank 2 is not provided with a backwash water tank heat exchanger 4.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was measured to be 85.8% at the time of initial use of the carbon-based catalyst.
The equipment is continuously operated, and after the COD removal rate is reduced to 43.5%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 7 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 66.5%. The activation rate was calculated to be 77.5% according to the COD removal rate of the carbon-based catalyst at the time of initial use and after regeneration.
Data analysis and conclusion: the significantly lower activation rate after regeneration of comparative example 4 compared to example 1 indicates that the carbon-based catalyst regeneration effect can be improved by preheating the sodium persulfate solution before the cyclic backwash. This is because the heating of the sodium persulfate solution to a desired temperature in the heating layer can be accelerated by the preheating, thereby generating more sulfate radicals, and removing the organic contaminants adhering to the carbon-based catalyst by oxidation to a greater extent.
Comparative example 5
The wastewater treatment and carbon-based catalyst regeneration apparatus structure employed in this comparative example was different from that of example 1 only in that: the heat insulating sphere layer was composed of heat insulating spheres (thermal conductivity 0.03W/(m.k)) having a diameter of 7 mm.
Organic wastewater (COD is 4000-5000 mg/L) generated by a certain coal chemical industry enterprise is used as test water. The wastewater is diluted 10 times, sodium persulfate is added according to the adding amount of 20 g/L, and then the wastewater is introduced into the reaction tower 1 from the liquid inlet 1-1 at the bottom of the tower, the flow rate of the wastewater in the reaction tower 1 is controlled to be 10 m/h, and the heating pipe 3 in the tower heats the wastewater, so that the water temperature after passing through the carbon-based catalyst layer is 75+/-5 ℃. COD values of the inlet water and the outlet water are detected at the position of the liquid inlet 1-1 at the bottom of the tower and the liquid outlet 1-2 at the top of the tower, and the COD removal rate is calculated according to the COD values. The COD removal rate was measured to be 82.0% at the time of initial use of the carbon-based catalyst.
The equipment is continuously operated, and after the COD removal rate is reduced to 46.7%, the operation is stopped, and the regeneration of the carbon-based catalyst is carried out, wherein the steps are as follows:
(1) Injecting a sodium persulfate solution with the concentration of 30 g/L into the backwash water tank 2, then introducing steam into the backwash water tank heat exchanger 4, heating the sodium persulfate solution to 40 ℃, and stopping introducing steam;
(2) Introducing steam into a heating pipe 3 in the reaction tower 1, starting a backwash water pump 9 and an exhaust valve 8, and pumping sodium persulfate solution in a backwash water tank 2 into the reaction tower 1;
(3) In the reaction tower 1, sodium persulfate solution enters from a liquid inlet 1-1 at the bottom of the tower, flows in the tower from bottom to top, has a flow rate of 7 m/h, has a water temperature of 75+/-5 ℃ after passing through the carbon-based catalyst layer, and finally flows out from a liquid outlet 1-2 at the upper part; CO 2 generated in the reaction tower 1 is discharged through an exhaust port 1-3 at the top of the tower;
(4) Introducing the liquid flowing out from the upper liquid outlet 1-2 into the backwashing water tank 2, naturally radiating the heat in the flowing process in the pipeline during the period, and then pumping the liquid into the reaction tower 1 through the backwashing water pump 9;
(5) Circularly performing the steps (3) - (4) for 4 times;
(6) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then closing a liquid discharge valve 7, changing the sodium persulfate solution into pure water, and washing according to the steps (1) - (5);
(7) Opening a liquid discharge valve 7 to empty the liquid in the reaction tower 1; then the liquid discharge valve 7 is closed, the fan 5 is opened, steam is introduced into the air heat exchanger 6, hot air with the temperature of 75+/-2 ℃ is blown into the reaction tower 1 from the air inlet 1-4 at the lower part, and the blowing is continued until no obvious white steam exists at the air outlet 1-3.
After the regeneration of the carbon-based catalyst was completed, the apparatus was again used for wastewater treatment (the method was the same as the wastewater treatment method for performing the catalyst regeneration lead), and the COD removal rate was measured to be 65.7%. The activation rate was calculated to be 80.1% according to the removal rate of COD at the time of the initial use and after regeneration of the carbon-based catalyst.
Data analysis and conclusion: the lower activation rate after regeneration of comparative example 5 compared to example 1 shows that the use of two diameters of heat insulating balls mixed to form the heat insulating ball layer can improve the regeneration effect of the carbon-based catalyst. The heat insulation effect of the heat insulation ball layer can be improved and the disturbance effect of the heat insulation ball layer on the backwashing liquid can be improved due to the fact that the heat insulation balls with two diameters are mixed.
The raw materials and equipment used in the invention are common raw materials and equipment in the field unless specified otherwise; the methods used in the present invention are conventional in the art unless otherwise specified.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent transformation of the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims (10)

1. A method for in situ regeneration of a carbon-based catalyst, comprising the steps of:
(1) Introducing backwash liquid containing persulfate into a reaction tower with a carbon-based catalyst layer from the bottom of the tower, wherein the carbon-based catalyst layer is filled with deactivated carbon-based catalyst;
(2) In the reaction tower, the reverse washing liquid flows from bottom to top at a flow rate of not higher than 7 m/h, and the catalyst regeneration is carried out in the following way one or the other way:
Mode one: the reverse washing liquid flows through the heat insulation ball layer, then enters the heating layer for heating, and then flows into organic pollutants attached to the carbon-based catalyst in the carbon-based catalyst layer attached to the upper part of the heating layer;
Mode two: the reverse washing liquid firstly flows through the heat insulation sphere layer and then enters the carbon-based catalyst layer to heat and oxidize organic pollutants attached to the carbon-based catalyst;
(3) The reverse washing liquid flows out from the upper part of the reaction tower and then is introduced from the bottom of the reaction tower;
(4) And (5) circularly carrying out the steps (2) - (3).
2. The method for in-situ regeneration of a carbon-based catalyst according to claim 1, wherein in the step (2), the temperature of the backwash liquid after passing through the carbon-based catalyst layer is 70-80 ℃.
3. The method for in-situ regeneration of a carbon-based catalyst according to claim 1 or 2, wherein in the step (1), the backwash liquid is preheated to 35-40 ℃ before being introduced into the reaction tower.
4. The method for in-situ regeneration of a carbon-based catalyst according to claim 1, wherein in the step (2), the heat-insulating sphere layer is formed by mixing heat-insulating spheres with diameters of 3-5 mm and 8-12 mm, respectively.
5. The method for in-situ regeneration of a carbon-based catalyst according to claim 1, wherein in the step (2), the thickness of the thermal insulation sphere layer is 4-10 cm.
6. The method for in-situ regeneration of a carbon-based catalyst according to claim 1, wherein after the step (4), the liquid in the reaction tower is drained, the reverse washing liquid in the steps (1) to (4) is replaced by pure water, and the carbon-based catalyst is washed according to the steps (1) to (4).
7. The method for in-situ regeneration of a carbon-based catalyst according to claim 6, wherein after the water washing is completed, the liquid in the reaction tower is emptied, hot air is blown into the reaction tower, and the carbon-based catalyst is purged until no obvious white steam exists in the outlet gas at the top of the reaction tower.
8. The method for in-situ regeneration of a carbon-based catalyst according to claim 7, wherein the temperature of the hot air is 70-80 ℃.
9. The in-situ carbon-based catalyst regeneration method according to claim 1, wherein in the step (4), the number of times of circularly performing the steps (2) - (3) is 3-5.
10. The method for in-situ regeneration of a carbon-based catalyst according to claim 1, wherein in the step (1), the concentration of persulfate in the backwash liquid is 0.05-0.3 mol/L.
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