CN1304090C - Reactor for harnessing flue gas by free radical showering in DC corona discharge - Google Patents

Abstract

The invention discloses a reactor for controlling flue gas by direct current corona discharge free radical shower. It has a rectangular shell with an air inlet and an air outlet at both ends of the shell. There are multiple corona discharge units inside the rectangular shell. Each corona discharge unit has two pole plates. The nozzle electrodes are connected with the gas collector respectively. The invention adopts the discharge nozzle electrode, and only uses corona discharge to activate a small amount of added gas injected into the flue, instead of performing high-energy treatment on all the flue gas, which will not activate the background components in the flue gas, and can effectively reduce free radicals Generated energy consumption. Multiple discharge nozzle electrodes are arranged in parallel in each corona discharge unit, forming multiple stable discharge channels between the plates, greatly increasing the corona area, and realizing multi-stage removal of pollutants during the flow of flue gas remove. Multiple corona discharge units are placed in parallel, and the requirements for different flue gas volumes can be met by increasing or decreasing the corona discharge units.

Description

Reactor for Flue Gas Treatment of Free Radical Shower by DC Corona Discharge

technical field

The invention relates to a reactor for controlling flue gas by direct current corona discharge free radical shower.

Background technique

Plasma flue gas treatment technology is an effective flue gas treatment technology, which includes electron beam method, pulse corona method and DC corona method. However, the high-energy electrons produced by the electron beam method can destroy the chemical bonds of the main gas molecules in the flue gas, so the gas molecules such as _N2 and _CO2 with high content in the flue gas will also be decomposed and ionized, wasting energy and causing The energy consumption of the process is too large; and there are problems such as the short life of the electron gun and the target window used, the complex structure of the equipment, the large footprint, and the shielding and protection of X-rays. Although the energy consumption of the pulsed corona method is only 50% of that of the electron beam method, it can still decompose and ionize gas molecules such as _N2 and _CO2 in the flue gas, wasting energy. In addition, this technology also has the disadvantages of complex manufacturing of high-power pulse power supply, high cost, short life of spark switch, and regular replacement.

DC corona discharge is a form of discharge generated by utilizing the uneven distribution of electric field between electrodes under the action of DC high voltage. With the conventional reactor structure, such as wire barrel structure and wire plate structure, the corona area of flue gas DC corona discharge is small, limited to the vicinity of the corona electrode, and the discharge current is relatively weak, so the efficiency of pollutant removal is relatively low. Low. And if the operating voltage is increased, it is easy to form spark breakdown. In order to increase the DC corona current to improve the removal efficiency of pollutants in the flue gas, Fuji et al. adopted the so-called multi-needle-plate discharge structure. The characteristic of this electrode structure is that a single wire electrode is replaced by multiple needle electrodes, so that multiple discharge channels are formed in the air gap, which can increase the discharge current. Moreover, the needle electrode and the plate electrode are separated by a water layer to form a discharge form similar to dielectric barrier discharge. The research results show that the removal of pollutants in flue gas by this multi-needle-plate corona discharge reactor can reach a very high level. However, its disadvantage is that it consumes a lot of energy.

In the mid-1990s, Ohkaho and Chang et al proposed the desulfurization and denitrification process of DC corona free radical shower based on the flow stability principle of nozzle corona moment. The so-called nozzle corona moment is the tubular discharge electrode. Two tubular electrodes are symmetrically arranged at both ends of the reactor, and a strong corona discharge area is formed between the electrodes when positive and negative high voltages are respectively connected. The study found that if the normal temperature gas is passed into the corona moment of the nozzle, the flow of the gas can make the DC corona discharge very stable, and if the gas volume is adjusted properly, a stable streamer corona across the entire discharge air gap can be generated, which is beneficial to the flue gas. The removal of pollutants in the medium is quite helpful.

Contents of the invention

The object of the present invention is to provide a reactor for controlling flue gas by direct current corona discharge free radical shower.

It has a rectangular shell with an air inlet and an air outlet at both ends of the rectangular shell. There are multiple corona discharge units inside the rectangular shell. Each corona discharge unit has two plates with a distance of 100mm between the two plates. A plurality of discharge nozzle electrodes are arranged in parallel, and are respectively connected with the gas collecting pipes. The added gas enters the electrode of the discharge nozzle from the gas collector and is sprayed out from the nozzle. Both the pole plate and the discharge nozzle electrode are made of stainless steel.

The present invention adopts discharge nozzle electrodes. This electrode design makes the airflow velocity in the nozzle much faster than that of the flue gas in the reactor. The added gas of the flue gas is activated by corona discharge to generate active substances, instead of high-energy treatment of all flue gas, which will not activate the background components in the flue gas, and can effectively reduce the energy consumption of free radical generation. During the corona discharge process, the added gas decomposes near the nozzle to produce a variety of active substances, which can effectively remove a variety of pollutants in the flue gas, with high removal efficiency and energy utilization. For different pollutants, you can choose to add gas with different components. The invention adopts a plurality of nozzle electrodes arranged in parallel in each corona discharge unit, forming a plurality of stable discharge channels between the plates, greatly increasing the corona area, and realizing multi-level pollutants in the process of flue gas flow Removal, which greatly improves the removal efficiency of pollutants. The present invention adopts the way of placing a plurality of corona discharge units in parallel, and can meet the requirements of different flue gas volume treatment by increasing or decreasing the corona discharge units.

Description of drawings

Fig. 1 is the schematic diagram of the reactor structure of corona discharge free radical shower flue gas treatment;

Fig. 2 is the structural representation of corona discharge unit of the present invention;

Fig. 3 is a schematic diagram of the electrode structure of the discharge nozzle of the present invention.

Detailed ways

The invention provides a reactor for controlling flue gas by direct-current corona discharge free radical shower. A very high electric field strength is generated, resulting in the occurrence of corona discharge. The added gas enters from one end of the main pipe of the discharge nozzle electrode, and is quickly decomposed in the corona area after being sprayed out from the small nozzle, thereby producing a large number of active particles, which can effectively remove various pollutants in the flue gas. The discharge nozzle electrode used makes the airflow velocity in the nozzle much faster than the flue gas velocity in the reactor, so the added gas jet at the nozzle mouth makes it difficult for the flue gas to enter the corona area near the nozzle, and the probability of the added gas being decomposed in this area is greatly increased increase, thereby solving the defects of many discharge forms to decompose the background gas, and achieving the purpose of saving energy consumption.

For the reactor design of corona discharge free radical shower flue gas treatment, not only the stable generation of corona and the efficient removal of pollutants should be paid attention to, but also the treatment to adapt to different flue gas volumes should be paid attention to. Here, the corona discharge reactor adopts a design in which multiple discharge nozzle electrodes are arranged in parallel in each corona discharge unit, forming multiple stable discharge channels between the plates, greatly increasing the corona area, and allowing the flue gas to flow The multi-stage removal of pollutants is realized in the process, which greatly improves the removal efficiency of pollutants. The generation of corona largely depends on the distance between the electrodes. If the distance between the electrodes is too large, the corona will not be stable and difficult to generate. If the distance between the electrodes is too small, the flue gas treatment capacity will be reduced. Therefore, we have chosen a distance of 100mm between the electrodes. . In the actual application process, a single corona unit is often unable to meet the large flow of flue gas treatment, so the present invention adopts the method of placing multiple corona discharge units in parallel, and can meet the requirements of different flue gas treatment by increasing or decreasing the corona discharge unit . The difficulty of corona discharge is also related to the material of the electrode. Generally speaking, tungsten, stainless steel and copper are good electrode materials for the discharge nozzle. Considering the corrosion of acid gas in the flue gas, the reactor is made of stainless steel.

As shown in FIG. 1 , the reactor for corona discharge free radical shower flue gas treatment has a rectangular shell 5 , and the two ends of the rectangular shell are provided with an air inlet 3 and an air outlet 4 . The corona discharge reactor can be divided into multiple corona discharge units according to the flue gas treatment capacity, and each corona discharge unit is separated by a plate 1, and the distance between the plates is 100mm. A certain number of discharge nozzle electrodes are arranged side by side in each corona discharge unit, and the discharge nozzle electrodes are placed perpendicular to the pole plate. In the design process, according to the size of the flue gas treatment capacity, we can choose the appropriate number of corona discharge units and the number of discharge nozzle electrodes arranged in each unit. Because the corona discharge characteristics are only related to the electrode spacing under the condition of constant flue gas conditions, the corona inception voltage and breakdown voltage of the discharge will not change with the number of corona discharge units and the number of discharge nozzle electrodes. Change, it only affects the size of the discharge current.

As shown in FIG. 2 , the corona discharge unit has two pole plates 1 , and a plurality of discharge nozzle electrodes 2 are arranged in parallel between the two pole plates, and are respectively connected to gas collectors 6 . They are all made of stainless steel. The added gas enters through the gas collecting pipe and sprays out from the nozzle of the discharge nozzle electrode. The electrodes of the discharge nozzle are connected to positive high voltage, and negative high voltage is applied on the plate. Due to the small radius of curvature at the tip of the nozzle, a very high electric field strength is generated near it, which results in a positive corona. After the additive gas is sprayed out from the nozzle, it is rapidly decomposed in the corona area, thereby producing a large number of active particles, which can effectively remove various pollutants in the flue gas.

As shown in Figure 3, the discharge nozzle electrode has a main tube 8, one end of which is open and the other end is closed, and a plurality of symmetrically or staggeredly distributed nozzles 7 are arranged on the main tube, and the length of the nozzles is 3-7mm. The radii and lengths of the header and nozzles can be varied on a case-by-case basis. Since the radius of curvature of the nozzle is very small, a strong electric field is easily formed between the nozzle and the plate, resulting in corona discharge. The added gas enters from one end of the electrode main pipe of the discharge nozzle, and then sprays out from the nozzle. After the additive gas is ejected from the nozzle, it is rapidly decomposed in the corona area, thereby producing a large number of active particles, which can effectively remove various pollutants in the flue gas. Moreover, the added gas entering the main pipe forms a jet flow at the nozzle opening, and its velocity is much greater than the flow rate of the flue gas. In this way, the added gas jet in the nozzle makes it difficult for the smoke to enter the corona area near the nozzle, and the probability of the added gas being decomposed in this area is greatly increased, thus solving the defects of many discharge forms to decompose the background gas, only for a small amount The shower gas injected into the flue is activated to generate free radicals, which can effectively reduce the energy consumption of free radicals.

Claims (3)

1. the reactor of a dc corona discharge free radical shower smoke gas treatment, it is characterized in that it has rectangle housing (5), the housing two ends are provided with air inlet (3) and gas outlet (4), be provided with a plurality of corona discharges unit in the rectangle housing, every corona discharge unit has two-plate (1), the parallel a plurality of discharge injector electrodes (2) that are provided with between two-plate, and join with discharge respectively (6), the discharge injector electrode has female pipe (8), female pipe one end opening, the sealing of female pipe other end, the nozzle (7) that on female pipe, is provided with a plurality of symmetrical distributions or is interspersed.

2. according to the reactor of a kind of dc corona discharge free radical shower smoke gas treatment of claim 1, it is characterized in that said two-plate spacing is 100mm.

3. according to the reactor of a kind of dc corona discharge free radical shower smoke gas treatment of claim 2, the length that it is characterized in that said nozzle is 3-7mm.

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