CN-117883966-B - Low-temperature plasma catalytic treatment system and method for organic waste gas

Abstract

The invention relates to the technical field of waste gas treatment, and discloses a low-temperature plasma catalytic treatment system and method for organic waste gas. The system comprises a first reaction unit, a second reaction unit, a third reaction unit, an ozone generator (18) and a COx filter (19), wherein the first reaction unit is a plasma reactor connected with a high-voltage power supply, the second reaction unit comprises more than two plasma reactors connected with the high-voltage power supply, and the third reaction unit is a reactor filled with a transition metal oxide catalyst. By the technical scheme provided by the invention, the degradation of VOCs in the oxygen-deficient waste gas can be realized under the conditions of lower operation cost and no change of gas composition.

Inventors

• LI CHAO
• Bao Hanchun
• ZHU XIAO
• ZHAO QIANBIN
• DU YU
• Tang Shiya
• GUAN YINXIA
• GUO YAFENG

Assignees

• 中国石油化工股份有限公司
• 中石化安全工程研究院有限公司

Dates

Publication Date

20260508

Application Date

20221008

Claims (14)

1. 1. The low-temperature plasma catalytic treatment system for the organic waste gas is characterized by comprising a first reaction unit, a second reaction unit, a third reaction unit, an ozone generator (18) and a COx filter (19), wherein the first reaction unit is a plasma reactor connected with a high-voltage power supply, the second reaction unit comprises more than two plasma reactors connected with the high-voltage power supply, and both the second reaction unit and the third reaction unit are reactors filled with a transition metal oxide catalyst; The gas supply source supplies the organic waste gas to be treated to the first reaction unit through a pipeline with a valve, or supplies the organic waste gas to be treated to each reactor of the second reaction unit through a pipeline with a valve; the outlet of the first reaction unit is respectively connected with the inlets of the reactors of the second reaction unit through pipelines with valves; the outlet of the ozone generator (18) is respectively connected with the inlets of the reactors of the second reaction unit through pipelines with valves; The outlets of the reactors of the second reaction unit are respectively connected with the inlet of the third reaction unit through pipelines with valves, so that the gas discharged from the reactors of the second reaction unit can enter the third reaction unit singly or after being combined; the outlets of the reactors of the second reaction unit are respectively connected with the inlet of the COx filter (19) through pipelines with valves, so that the gas discharged from the reactors of the second reaction unit can enter the COx filter (19) singly or after being combined; The outlet of the third reaction unit is connected with the inlet of the COx filter (19) through a pipeline with a valve.
2. 2. The system according to claim 1, further comprising a total hydrocarbon analyzer (20) for monitoring the total hydrocarbon concentration of the gas discharged from the outlet of each reactor of the second reaction unit or for monitoring the total hydrocarbon concentration in the gas after merging of the gases discharged from the outlet of each reactor of the second reaction unit.
3. 3. The system according to claim 1 or 2, further comprising a first ozone analyzer (21) for monitoring the ozone concentration of the gas discharged from the outlet of each reactor of the second reaction unit.
4. 4. The system according to claim 1 or 2, further comprising a second ozone analyzer (22) for monitoring the ozone concentration of the gas discharged from the outlet of the third reaction unit.
5. 5. A method for the low temperature plasma catalytic treatment of organic waste gases, characterized in that it is carried out in a system according to any one of claims 1-4, said method comprising: (1) Determining the treatment requirements of organic waste gas, wherein the treatment requirements of the organic waste gas comprise continuous circulation after waste gas treatment or direct discharge after waste gas treatment; (2) Determining the oxygen content of the organic waste gas; (3) And according to different treatment requirements and oxygen contents of the organic waste gas, inputting the organic waste gas into the system for treatment according to different operation schemes.
6. 6. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is continuously circulated after the treatment, and the oxygen content of the organic waste gas is 1% or less, (I) Supplying the organic waste gas in the gas supply source to the first reactor (2-1) in the second reaction unit for treatment, then treating by the COx filter (19), and then recycling to the gas supply source and continuing the recycling treatment; (II) feeding the organic waste gas from the gas supply to a second reactor (2-2) in the second reaction unit for treatment when the total hydrocarbon concentration at the outlet of the first reactor (2-1) exceeds an emission standard; (III) inputting ozone into the first reactor (2-1) through the ozone generator (18), and allowing excess ozone discharged from the first reactor (2-1) to enter the third reaction unit for treatment, and stopping inputting ozone into the first reactor (2-1) when the outlet ozone concentration of the first reactor (2-1) is the same as the inlet ozone concentration; (IV) if the total hydrocarbon concentration at the outlet of the second reactor (2-2) exceeds the emission standard, referring to steps (I) to (III), re-feeding the organic waste gas in the gas supply source to the first reactor (2-1) or other reactor in the second reaction unit, inputting ozone to the second reactor (2-2) through the ozone generator (18); (V) repeating the steps (I) to (IV).
7. 7. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is continuously circulated after the treatment, and the oxygen content of the organic waste gas is more than 1% and 10% or less, (I) Supplying the organic waste gas in the gas supply source to the first reaction unit for treatment; (II) feeding the organic waste gas discharged from the first reaction unit to a first reactor (2-1) in the second reaction unit for treatment, followed by treatment by the COx filter (19), and then recycling to the gas supply source and continuing the recycling treatment; (III) when the total hydrocarbon concentration at the outlet of the first reactor (2-1) exceeds an emission standard, transferring the organic waste gas discharged from the first reaction unit to a second reactor (2-2) in the second reaction unit for treatment; (IV) inputting ozone into the first reactor (2-1) through the ozone generator (18), and allowing excess ozone discharged from the first reactor (2-1) to enter the third reaction unit for treatment, and stopping inputting ozone into the first reactor (2-1) when the outlet ozone concentration of the first reactor (2-1) is the same as the inlet ozone concentration; (V) if the total hydrocarbon concentration at the outlet of the second reactor (2-2) exceeds the emission standard, referring to steps (II) to (IV), re-supplying the organic waste gas discharged from the first reaction unit to the first reactor (2-1) or the other reactor in the second reaction unit, and inputting ozone to the second reactor (2-2) through the ozone generator (18); (VI) repeating the steps (II) to (V).
8. 8. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is continuously circulated after the treatment, and the oxygen content of the organic waste gas is more than 10% and 20% or less, (I) Supplying the organic waste gas in the gas supply source to the first reaction unit for treatment; (II) the organic waste gas discharged from the first reaction unit is sent to a first reactor (2-1) in the second reaction unit for treatment, then sent to the third reaction unit for treatment, then treated by the COx filter (19), and then recycled to the gas supply source and the recycling treatment is continued; (III) when the total hydrocarbon concentration at the outlet of the first reactor (2-1) exceeds an emission standard, transferring the organic waste gas discharged from the first reaction unit to a second reactor (2-2) in the second reaction unit for treatment; (IV) inputting ozone into the first reactor (2-1) through the ozone generator (18), and allowing excess ozone discharged from the first reactor (2-1) to enter the third reaction unit for treatment, and stopping inputting ozone into the first reactor (2-1) when the outlet ozone concentration of the first reactor (2-1) is the same as the inlet ozone concentration; (V) if the total hydrocarbon concentration at the outlet of the second reactor (2-2) exceeds the emission standard, referring to steps (II) to (IV), re-supplying the organic waste gas discharged from the first reaction unit to the first reactor (2-1) or the other reactor in the second reaction unit, and inputting ozone to the second reactor (2-2) through the ozone generator (18); (VI) repeating the steps (II) to (V).
9. 9. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is directly discharged after the treatment, and the oxygen content of the organic waste gas is 1% or less, (I) Organic waste gas in a gas supply source is respectively supplied to all reactors in the second reaction unit for treatment, and ozone is respectively input into all reactors in the second reaction unit through the ozone generator (18); (II) increasing the ozone inlet gas concentration or flow rate when the total hydrocarbon concentration of the mixed gas discharged from the second reaction unit exceeds the emission standard, or increasing the discharge voltage of each reactor in the second reaction unit until the total hydrocarbon concentration of the mixed gas is lower than the emission standard.
10. 10. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is directly discharged after the treatment, and the oxygen content of the organic waste gas is more than 1% and 10% or less, (I) Supplying the organic waste gas in the gas supply source to the first reaction unit for treatment; (II) delivering the organic waste gas discharged from the first reaction unit to all the reactors in the second reaction unit for treatment respectively, and inputting ozone to all the reactors in the second reaction unit respectively through the ozone generator (18); (III) increasing ozone inlet gas concentration or flow rate when the total hydrocarbon concentration of the mixture gas discharged from the second reaction unit exceeds an emission standard, or increasing discharge voltage of each reactor in the second reaction unit until the total hydrocarbon concentration of the mixture gas is below the emission standard.
11. 11. The method according to claim 5, wherein when the treatment requirement of the organic waste gas is that the waste gas is directly discharged after the treatment, and the oxygen content of the organic waste gas is more than 10% and 20% or less, (I) Supplying the organic waste gas in the gas supply source to the first reaction unit for treatment; (II) the organic waste gas discharged from the first reaction unit is respectively conveyed to all reactors in the second reaction unit for treatment; (III) increasing the discharge voltage of each reactor in the second reaction unit when the total hydrocarbon concentration of the mixture discharged from the second reaction unit exceeds the discharge standard, or respectively inputting ozone into all reactors in the second reaction unit through the ozone generator (18) and adjusting the inlet gas concentration or flow of ozone until the total hydrocarbon concentration of the mixture is below the discharge standard.
12. 12. The method according to any one of claims 5-11, wherein the reactor of the first reaction unit is filled with ferroelectric material; the ferroelectric material is a natural crystal and/or a synthetic crystal, the natural crystal is at least one of barium titanate, potassium dihydrogen phosphate and sodium nitrite, and the synthetic crystal is a crystal which is obtained based on the modification of the natural crystal and has further enhanced polarization effect under a high-voltage electric field.
13. 13. The method according to any one of claims 5 to 11, wherein the reactor of the second reaction unit is packed with a first transition metal oxide catalyst in which the active component is a transition metal oxide, wherein the transition metal is one or any combination of at least two of Sc, ti, V, cr, mn, fe, co, ni, cu and Zn, and the carrier is alumina, activated carbon, molecular sieves or MOFs.
14. 14. The method according to any one of claims 5 to 11, wherein the reactor of the third reaction unit is filled with a second transition metal oxide catalyst in which the active component is a transition metal oxide, wherein the transition metal is one or any combination of at least two of Sc, ti, V, cr, mn, fe, co, ni, cu and Zn, and the carrier is alumina, activated carbon, molecular sieves or MOFs.

Description

Low-temperature plasma catalytic treatment system and method for organic waste gas Technical Field The invention relates to the technical field of waste gas treatment, in particular to a low-temperature plasma catalytic treatment system and method for organic waste gas. Background Volatile Organic Compounds (VOCs) are organic compounds with saturated vapor pressure of more than 70Pa and boiling point of less than 260 ℃ under normal pressure at normal temperature, or all organic compounds with vapor pressure of more than or equal to 10Pa and volatility at 20 ℃ and comprise non-methane hydrocarbon, halogenated hydrocarbon, oxygen-containing organic compounds, nitrogen-containing organic compounds, sulfur-containing organic compounds and the like, and the volatile organic compounds mainly come from industrial production processes such as organic chemical industry, petroleum refining, printing, spraying, solvent use and the like. VOCs are not only important precursors leading to haze and photochemical smog, but also cause great harm to human health due to the pungent odor and biotoxicity. In general, the treatment methods of organic waste gas are mainly classified into two types, and for high-concentration organic waste gas with recovery value, recovery techniques such as membrane separation, adsorption method and absorption method are generally adopted, and for low-concentration organic waste gas without recovery value, destruction techniques such as thermal storage combustion method, catalytic oxidation method, biological method, low-temperature plasma method and photocatalysis method are generally adopted. The organic waste gas destruction technique can be briefly described as oxidizing VOCs with oxygen in the air through a series of physical, chemical and biological reactions, and finally mineralizing into CO 2 and H 2 O. Oxygen is therefore an important reaction condition for degradation of VOCs. Although most of the organic waste gas discharged in the industrial production process is composed by taking air as a background, part of the organic waste gas generated by the process and the device is composed by taking inert gas as a main background, and the oxygen content is low. For example, in the first case, oxygen is taken as one of the reactants to participate in the organic synthesis reaction process, resulting in a reduction in the oxygen content of the discharged organic waste gas, and in the second case, inert gas is taken as a recycle protection gas for preventing oxidation of organic products, VOCs are gradually accumulated in the inert recycle gas, not only reducing the product performance, but also damaging the device performance. Aiming at the first condition of generating oxygen-deficient organic waste gas, after a certain amount of air is mixed, VOCs degradation can be realized by adopting a destroying technology, but the defect is that the treatment scale of the device is required to be improved due to larger waste gas amount. Aiming at the second condition of generating the oxygen-deficient organic waste gas, if the organic waste gas is treated by adopting a destroying technology after a small amount of air is mixed, the degradation efficiency of VOCs can not be ensured, and in order to prevent the oxidation of organic products, gas separation equipment is added to control the rising oxygen concentration in the circulating gas caused by the introduction of air, and if VOCs are collected by adopting an adsorption technology, a treatment device for enriching the waste gas is added or related enterprises are entrusted to regenerate the adsorbent. In summary, the conventional method or process combination is adopted to degrade the oxygen-deficient organic waste gas under both conditions, so that the treatment cost of the waste gas can be greatly increased. Therefore, how to control the treatment cost of the waste gas and ensure the efficient degradation of VOCs becomes a problem to be solved in the urgent need of treating the oxygen-deficient organic waste gas. Disclosure of Invention The invention aims to provide a low-temperature plasma catalytic treatment system and a low-temperature plasma catalytic treatment method for organic waste gas, and VOCs in the organic waste gas can be effectively removed at lower cost according to the technical scheme of the invention. In order to achieve the above object, according to one aspect of the present invention, there is provided a low temperature plasma catalytic treatment system for organic exhaust gas, the system comprising a first reaction unit, a second reaction unit, a third reaction unit, an ozone generator and a COx filter, wherein the first reaction unit is a plasma reactor connected to a high voltage power supply, the second reaction unit comprises two or more plasma reactors connected to a high voltage power supply, and the third reaction unit is a reactor filled with a transition metal oxide catalyst; The gas supply source supplies the organic