A reaction pipeline suitable for gas phase trace persistent organic pollutants

Abstract

The present invention discloses a reaction pipeline suitable for gas phase trace persistent organic pollutants, and relates to the technical field of dioxin emission reduction research. It includes: a liquid inlet pipe, which inputs dioxin stock solution; an atomizer, which atomizes the dioxin stock solution into droplets; a carrier gas pipeline, which is used to input carrier gas; a diverter valve, which diverts the carrier gas into a first gas flow and a second gas flow; a reaction tube, which includes an adjacent inner cavity and an outer cavity, wherein the first gas flow is mixed with the droplets and then transports the droplets to the inner cavity, and the second gas flow enters the outer cavity alone; a plurality of air film holes are arranged on the wall between the inner cavity and the outer cavity; the second gas flow enters the inner cavity through the air film holes, and forms an air film on the surface of the inner cavity to prevent the droplets transported by the first gas flow from being deposited on the surface of the inner cavity. The present invention can prevent the dioxins transported by the carrier gas from being adsorbed on the tube wall, and avoid the problem of difficult concentration stabilization and waste of dioxin stock solution.

Description

Technical Field

[0001] The invention relates to the technical field of dioxin emission reduction research, and in particular to a reaction pipeline suitable for gas phase trace persistent organic pollutants. Background Art

[0002] Persistent organic pollutants (POPs) refer to chemical substances synthesized by humans that can persist in the environment, accumulate through the biological food chain (web), and cause harmful effects on human health. These substances can cause harm to the health of organisms even at extremely low concentrations. Dioxins are a representative class of trace persistent organic pollutants, including 75 polychlorinated dibenzodioxins (PCDDs) isomers and 135 polychlorinated dibenzofurans (PCDFs) isomers. Dioxins are chemically stable, difficult to dissolve in water, easily soluble in fat, and accumulate in organisms, and are not easy to decompose. They are carcinogenic, teratogenic, and reproductively toxic to humans, and are listed as one of the 12 persistent organic pollutants in the Stockholm Convention. Researchers have conducted a lot of in-depth research on the emission characteristics and emission reduction technologies of dioxins in incineration flue gas, mainly including activated carbon adsorption technology, catalytic oxidation degradation technology, ultraviolet light / ozone assisted catalytic oxidation decomposition technology, etc. In order to explore the dioxin adsorption mechanism and develop activated carbon materials with better performance, experimental research must first be carried out on a small-scale laboratory-scale experimental device.

[0003] Laboratory-scale research on dioxins is mainly carried out using fixed-bed reactors. However, due to the extremely low concentration, extremely low volatility and extreme toxicity of dioxins, it is difficult for general researchers to produce stable dioxin source gas and control its concentration under laboratory conditions.

[0004] The dioxin source device currently used (ZL 201220322349.3) is mainly composed of a micro-injection pump CMA400 (CMA Microdialysis AB, USA), a micro-injection syringe (1 mL), an atomizer (Meinhard USA), and a preheated reaction tube. The micro-injection pump delivers the dioxin stock solution (solvent is nonane) in the syringe to the atomizer at a constant rate (1nl / min-1ml / min). The carrier gas is a nitrogen-oxygen mixed gas, which is controlled by a mass flow meter. After the dioxin solution is fully atomized through the atomizer, it enters the preheating section (205 ℃). Nonane burns with oxygen in the atmosphere in the preheating section, and dioxin enters the quartz tube with the carrier gas for the next reaction. However, since the dioxin concentration in the carrier gas is at a trace level and has a high boiling point, it is very easy to adsorb on the tube wall, requiring a very long stabilization time (6-8 hours), and there is a problem of waste of dioxin stock solution and a potential risk of environmental leakage.

[0005] Therefore, the development of a more reliable and efficient laboratory-scale dioxin stabilization generation device is of great significance to the advancement of dioxin emission reduction and control research. Summary of the invention

[0006] In order to solve at least one of the technical problems mentioned in the background technology, the purpose of the present invention is to provide a reaction pipeline suitable for gas phase trace persistent organic pollutants, which can prevent dioxins transported by carrier gas from being adsorbed on the tube wall, avoid the problem of difficult concentration stability and waste of dioxin stock solution.

[0007] In a first aspect, the present invention provides a reaction pipeline suitable for gas phase trace persistent organic pollutants, comprising:

[0008] Liquid inlet pipe, used for inputting dioxin stock solution;

[0009] An atomizer, disposed at the end of the liquid inlet pipe, atomizes the dioxin stock solution into droplets;

[0010] A carrier gas pipeline, used for inputting carrier gas;

[0011] A splitter valve, which splits the carrier gas into a first airflow and a second airflow, wherein the splitter valve comprises an air inlet, a first air outlet and a second air outlet, wherein the air inlet is connected to the carrier gas pipeline, the first air outlet is used to output the first airflow, and the second air outlet is used to output the second airflow;

[0012] The reaction tube includes an adjacent inner cavity and an outer cavity. A first airflow mixes with droplets and transports the droplets to the inner cavity, and a second airflow enters the outer cavity alone. A plurality of air film holes are arranged on the wall between the inner cavity and the outer cavity. The second airflow enters the inner cavity through the air film holes and forms an air film on the surface of the inner cavity to prevent the droplets transported by the first airflow from being deposited on the surface of the inner cavity.

[0013] In certain embodiments of the first aspect of the present invention, a diffuser tube for increasing the pressure of the second gas flow is further provided between the diverter valve and the reaction tube.

[0014] In certain embodiments of the first aspect of the present invention, the diffuser tube includes an inner flow channel and an outer flow channel; the inlet of the inner flow channel is connected to the outlet of the atomizer and the first air outlet, and the outlet is connected to the inner cavity to allow a mixed airflow of the first airflow and droplets to flow; the inlet of the outer flow channel is connected to the second air outlet, and the outlet is connected to the outer cavity to allow a second airflow to flow, and the outer flow channel tends to gradually expand from the inlet to the outlet.

[0015] In certain embodiments of the first aspect of the present invention, a plurality of guide plates extending from the inlet to the outlet are arranged at intervals in the outer flow channel.

[0016] In certain embodiments of the first aspect of the present invention, the intervals between adjacent guide plates gradually increase from the inlet to the outlet.

[0017] In certain embodiments of the first aspect of the present invention, the air film hole forms a first angle with a flow direction of a mixed airflow of the first airflow and droplets in the inner cavity, and the first angle is 10° to 50°.

[0018] In certain embodiments of the first aspect of the present invention, the first angle is 30°.

[0019] In certain embodiments of the first aspect of the present invention, a top cover is disposed outside the liquid inlet pipe, and the top cover is connected to the diverter valve.

[0020] In certain embodiments of the first aspect of the present invention, a gas outlet pipe is provided at the end of the reaction tube.

[0021] In certain embodiments of the first aspect of the present invention, a bottom cover is provided at the end of the reaction tube, and the gas outlet pipe passes through the bottom cover.

[0022] In a second aspect, the present invention provides a trace / micro organic pollutant generating device, comprising:

[0023] The reaction pipeline as described in the first aspect;

[0024] A trace / micro syringe, used to inject the dioxin stock solution into the liquid inlet tube;

[0025] The heating device is used to heat the reaction tube.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention divides the carrier gas into two paths, one of which is used as normal carrier gas to transport dioxins, and the other is used as protective gas to form an air film in the inner cavity of the reaction tube to prevent the droplets transported by the first gas flow from depositing on the surface of the inner cavity, thereby avoiding the problem of difficult concentration stabilization and waste of dioxin stock solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 It is a cross-sectional view from a first viewing angle of the present invention.

[0030] Figure 3 It is a cross-sectional view of the present invention in a three-dimensional state.

[0031] Figure 4 for Figure 2 A partial enlarged view of point A in the middle.

[0032] Figure 5 for Figure 2 A partial enlarged view of point B in the middle.

[0033] Figure 6 It is a schematic diagram of the structure of the diffuser tube of the present invention.

[0034] In the figure:

[0035] 1. Liquid inlet pipe;

[0036] 2. Atomizer;

[0037] 3. Carrier gas pipeline;

[0038] 4. Diverter valve; 41. Air inlet; 42. First air outlet; 43. Second air outlet;

[0039] 5. Diffuser; 51. Inner flow channel; 52. Outer flow channel; 53. Guide plate;

[0040] 6. reaction tube; 61. inner cavity; 611. air film hole; 62. outer cavity;

[0041] 7. Exhaust pipe;

[0042] 8. Top cover;

[0043] 9. Bottom cover. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Embodiment 1:

[0046] The present invention provides a reaction pipeline suitable for gas phase trace persistent organic pollutants, please refer to Figures 1 to 3 The reaction pipeline includes: a liquid inlet pipe 1, an atomizer 2, a carrier gas pipeline 3, a diverter valve 4, a reaction tube 6 and a gas outlet pipe 7.

[0047] Liquid inlet pipe 1, used for inputting dioxin stock solution;

[0048] The atomizer 2 is arranged at the end of the liquid inlet pipe 1 and atomizes the dioxin stock solution into droplets;

[0049] A carrier gas pipeline 3, used for inputting carrier gas;

[0050] The diverter valve 4 diverts the carrier gas into a first gas flow and a second gas flow. Figure 4The diverter valve 4 includes an air inlet 41, a first air outlet 42 and a second air outlet 43. The air inlet 41 is connected to the carrier gas pipeline 3, so as to guide the input carrier gas to the inside of the diverter valve 4. The hollow arrow in the figure represents the flow direction of the carrier gas. The first air outlet 42 is formed on the wall of the diverter valve on the side of the atomizer, and is used to output the first airflow; the second air outlet 43 is located at the end opening of the diverter valve, and is used to output the second airflow.

[0051] The reaction tube 6 includes an inner cavity 61 and an outer cavity 62 adjacent to each other. A heating jacket or other heating equipment is arranged outside the reaction tube 6 to heat the reaction tube. The first airflow is used as a normal carrier gas to mix with the droplets and transport the droplets to the inner cavity 61. The second airflow enters the outer cavity 62 alone. A plurality of air film holes 611 are arranged on the wall between the inner cavity 61 and the outer cavity 62. It is worth mentioning that the air film holes 611 are evenly distributed on the entire wall.

[0052] The second airflow passes through the air film holes 611 and enters the inner cavity 61 to form an air film on the surface of the inner cavity 61 to prevent the droplets transported by the first airflow from being deposited on the surface of the inner cavity 61, thereby avoiding the problem of difficult concentration stabilization and waste of dioxin stock solution.

[0053] like Figure 5 As shown, the air film hole 611 forms a first angle α with the flow direction of the mixed airflow of the first airflow and droplets in the inner cavity 61, and the first angle α is 10° to 50°, preferably 30°.

[0054] The gas outlet pipe 7 is arranged at the end of the reaction tube 6 and is used for outputting the gas after the reaction.

[0055] In this embodiment, a top cover 8 is further provided on the outside of the liquid inlet pipe 1 , and the top cover 8 is connected to the diverter valve 4 to fix the liquid inlet pipe 1 .

[0056] Similarly, a bottom cover 9 is provided at the end of the reaction tube 6 , and the gas outlet pipe 7 passes through the bottom cover 9 .

[0057] Embodiment 2:

[0058] In order to enhance the strength of the gas film 1 , the pressure of the second gas flow needs to be increased. Based on the first embodiment, the second embodiment further provides a diffuser 5 between the diverter valve 4 and the reaction tube 6 for increasing the pressure of the second gas flow.

[0059] Specifically, refer to Figure 3 and Figure 6 The diffuser tube 5 includes an inner flow channel 51 and an outer flow channel 52 .

[0060] The inlet of the inner flow channel 51 is communicated with the outlet of the atomizer 2 and the first air outlet 42 , and the outlet is communicated with the inner cavity 61 to allow the mixed airflow of the first airflow and the droplets to circulate.

[0061] The inlet of the outer flow channel 52 is communicated with the second air outlet 43, and the outlet is communicated with the outer cavity 62 for the second air flow to flow. The outer flow channel 52 has a gradually expanding trend from the inlet to the outlet.

[0062] A plurality of guide plates 53 extending from the inlet to the outlet are arranged at intervals in the outer flow channel 52, and the intervals between adjacent guide plates 53 gradually increase from the inlet to the outlet, thereby forming a plurality of gradually expanding flow channels. The gradually expanding flow channels can reduce the flow velocity of the inflowing gas and increase its pressure, so that the pressure in the outer cavity 62 also increases, thereby enhancing the strength of the air film formed on the surface of the inner cavity 61.

[0063] The following experiments demonstrate the effectiveness of this solution.

[0064] The effectiveness of the reaction pipeline was tested by the dioxin stabilization device. The experimental conditions were as follows: the dioxin stock solution inlet rate was controlled to be 1μL / min, the carrier gas flow rate was 500mL / min, the reaction temperature was 160℃, no adsorbent was used, the tail gas was absorbed by toluene in an ice bath, and one sample was taken every hour. Different stabilization times were selected, and three samples were taken for each condition.

[0065] Comparative Example 1

[0066] Using a conventional quartz tube reactor

[0067]

[0068] Example 1

[0069] Use anti-deposition reaction line

[0070]

[0071] Conventional quartz tube reactors need 8 hours of stabilization to meet experimental requirements, while the use of anti-adsorption and deposition pipelines only takes 2 hours to meet experimental requirements, saving experimental time, improving experimental accuracy, and reducing pollutant emissions.

[0072] In order to verify the control effect of this scheme at the trace level, the following experiments were conducted:

[0073] The experimental conditions are as follows: dilute the dioxin stock solution 100 times, control the dioxin stock solution inlet rate to 1μL / min, the carrier gas flow rate to 500mL / min, the reaction temperature to 160℃, no adsorbent is used, the tail gas is absorbed by toluene in an ice bath, and every 1 hour is taken as a sample. Different stabilization times are selected, and three samples are taken for each condition.

[0074] Comparative Example 2

[0075] Using a conventional quartz tube reactor

[0076]

[0077] Example 2

[0078] Use anti-deposition reaction line

[0079]

[0080] Conventional quartz tubes need to be stabilized for 8 hours to meet experimental requirements, while the new reaction pipeline can meet experimental requirements in 4 hours with higher precision.

[0081] Embodiment three:

[0082] This embodiment provides a trace / micro organic pollutant generating device, comprising:

[0083] The reaction pipeline as described in Example 1 or Example 2;

[0084] A trace / micro syringe, used to inject the dioxin stock solution into the liquid inlet tube;

[0085] The heating device is used to heat the reaction tube.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A reaction pipeline suitable for gas phase trace persistent organic pollutants, characterized in that: include: Liquid inlet pipe, used for inputting dioxin stock solution; An atomizer, disposed at the end of the liquid inlet pipe, atomizes the dioxin stock solution into droplets; A carrier gas pipeline, used for inputting carrier gas; A splitter valve, which splits the carrier gas into a first airflow and a second airflow, wherein the splitter valve comprises an air inlet, a first air outlet and a second air outlet, wherein the air inlet is connected to the carrier gas pipeline, the first air outlet is used to output the first airflow, and the second air outlet is used to output the second airflow; A reaction tube, comprising an adjacent inner cavity and an outer cavity, wherein a first airflow mixes with droplets and transports the droplets to the inner cavity, and a second airflow enters the outer cavity alone; a plurality of air film holes are arranged on the wall between the inner cavity and the outer cavity; the second airflow enters the inner cavity through the air film holes and forms an air film on the surface of the inner cavity to prevent the droplets transported by the first airflow from being deposited on the surface of the inner cavity; A pressure diffuser for increasing the pressure of the second airflow is also provided between the diverter valve and the reaction tube; the pressure diffuser includes an inner flow channel and an outer flow channel; the inlet of the inner flow channel is connected to the outlet of the atomizer and the first air outlet, and the outlet is connected to the inner cavity to allow the mixed airflow of the first airflow and the droplets to flow; the inlet of the outer flow channel is connected to the second air outlet, and the outlet is connected to the outer cavity to allow the second airflow to flow, and the outer flow channel has a gradual expansion trend from the inlet to the outlet; The air film hole forms a first angle with the flow direction of the mixed airflow of the first airflow and droplets in the inner cavity; the first angle is 30°.

2. A reaction pipeline suitable for gas phase trace persistent organic pollutants according to claim 1, characterized in that: A plurality of guide plates extending from the inlet to the outlet are arranged at intervals in the outer flow channel.

3. A reaction pipeline suitable for gas phase trace persistent organic pollutants according to claim 2, characterized in that: The intervals between adjacent guide plates gradually increase from the inlet to the outlet.

4. The reaction pipeline for gas phase trace persistent organic pollutants according to claim 1, characterized in that: A top cover is arranged outside the liquid inlet pipe, and the top cover is connected to the diverter valve.

5. The reaction pipeline suitable for gas phase trace persistent organic pollutants according to claim 1, characterized in that: The end of the reaction tube is provided with an air outlet pipe.

6. A reaction pipeline suitable for gas phase trace persistent organic pollutants according to claim 5, characterized in that: A bottom cover is arranged at the end of the reaction tube, and the gas outlet pipe passes through the bottom cover.

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