CN1304091C - Electrode of discharging nozzle in use for harnessing fume caused by DC corona discharge - Google Patents

Abstract

The invention discloses a discharge nozzle electrode used for direct current corona discharge flue gas treatment. It has a mother pipe, one end of which is open and the other end is closed, and a plurality of symmetrically distributed or staggered nozzles are arranged on the mother pipe. The invention has the advantages that the added gas fed into the electrode of the discharge nozzle is almost completely decomposed in the corona area, so even the polluting gas will not cause secondary pollution to the environment. In addition, because different additive gases can be decomposed in the corona area to generate different free radicals, the corresponding additive gas can be selected according to the treatment object in the flue gas. With this electrode design, the gas flow velocity in the nozzle is much faster than that of the flue gas in the reactor, so the added gas jet in the nozzle 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 defect of decomposing the background gas in many discharge forms, and greatly improving the energy efficiency.

Description

Discharge nozzle electrode for DC corona discharge flue gas treatment

technical field

The invention relates to a discharge nozzle electrode used for direct current corona discharge flue gas treatment.

Background technique

At present, the most commonly used plasma flue gas treatment technologies are 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; although the energy consumption of the pulse 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. Moreover, the electron beam method and the pulse corona method often add ammonia gas as an absorbent in the actual application process. The ammonia gas cannot be completely reacted, causing ammonia gas leakage, and discharge into the atmosphere will cause pollution to the surrounding environment.

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. If a conventional discharge electrode structure is adopted, such as a wire barrel structure and a wire plate structure, the corona area of the flue gas DC corona discharge is small, limited to the vicinity of the wire electrode, and the discharge current is relatively weak, so the pollutant removal effect is poor . And if the operating voltage is increased, it is easy to form a spark breakdown, resulting in unstable discharge. 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-pin-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 corona discharge area and increase the discharge current. The research results show that this multi-pin-plate corona discharge reactor can achieve a high level of removal of pollutants in the flue gas. However, its disadvantage is that it consumes a lot of energy.

In the mid-1990s, Ohkaho and Chang et al. proposed a method of using a discharge electrode with a nozzle structure for flue gas treatment based on the flow stability principle of the 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. 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, it can produce a stable streamer corona across the entire discharge air gap, which is harmful to the pollutants in the flue gas. The removal is quite helpful.

Contents of the invention

The purpose of the present invention is to provide a discharge nozzle electrode for direct current corona discharge smoke treatment.

It has a mother pipe, one end of which is open and the other end is closed, and a plurality of symmetrically distributed or staggered nozzles are arranged on the mother pipe.

Advantages of the present invention:

The added gas is almost completely decomposed in the corona area near the nozzle, so even polluting gases such as ammonia will not cause secondary pollution to the environment. At the same time, the flow of gas at the nozzle mouth can make the corona discharge more stable, and can generate a stable streamer corona across the entire discharge air gap. Since different additive gases can be decomposed in the corona zone to produce different free radicals, the corresponding additive gas can be selected according to the treatment object in the flue gas. With this electrode design, the gas flow velocity in the nozzle is much faster than that of the flue gas in the reactor, so the added gas jet in the nozzle 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 defect of decomposing the background gas in many discharge forms, and greatly improving the energy efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the discharge nozzle electrode structure with nozzles symmetrically distributed;

Fig. 2 is a schematic diagram of the structure of discharge nozzle electrodes with nozzles distributed in a staggered manner.

specific implementation plan

Aiming at the shortcomings of electron beam method and pulse corona method, a discharge nozzle electrode for DC corona discharge flue gas treatment is proposed. The added gas (gases such as NH ₃ , N ₂ , O ₂ and CO ₂ ) enters from one end of the discharge nozzle electrode main pipe, and then ejects rapidly from the nozzle. If a DC high voltage is applied to the electrode, a very high electric field intensity will be generated near the end of the nozzle due to the small curvature radius, resulting in the occurrence of corona discharge. The flow of gas can make the corona discharge more stable, and proper adjustment of the added gas flow can produce a stable streamer corona across the entire discharge air gap. After the added gas is ejected from the nozzle, it is quickly and effectively decomposed in the corona area, thereby generating a large number of free radicals (such as NH ₂ , NH, O, OH, O ₃ , HO _{2 ,} etc.), which can effectively remove the pollutants in the flue gas. various pollutants.

As shown in the figure, the discharge nozzle electrode has a main pipe 2, one end of which is open and the other end is closed, and a plurality of nozzles 1 are arranged on the main pipe. The radius of the mother pipe is 8-10mm, the length of the nozzle is 3-7mm, and the radius is 2-4mm. The nozzles on the main pipe can be symmetrically distributed or staggeredly distributed, and each nozzle can form an independent discharge channel. In order to make the corona cover the entire discharge air gap as much as possible, the distance between the nozzles on the main pipe is generally controlled at 15-25mm. The discharge nozzle electrode material is stainless steel. The added gas is introduced from the open end of the main pipe. Since the nozzle radius is small, a strong jet can be formed at the nozzle opening to prevent the smoke from entering the corona area near the nozzle, which can effectively reduce the decomposition of the background gas and improve energy efficiency. After the added gas is ejected from the nozzle, it is rapidly decomposed in the corona area near the nozzle, thereby generating a large number of free radicals, which can effectively remove various pollutants in the flue gas. Since different additive gases can generate different free radicals during the discharge process, the corresponding additive gas can be selected according to the treatment object in the flue gas.

Claims (5)

1. a discharge injector electrode that is used for governing direct-current corona discharge smoke is characterized in that it has female pipe (2), female pipe one end opening, other end sealing, the nozzle (1) that is provided with tool a plurality of symmetrical distributions at regular intervals or is interspersed on female pipe.

2. according to a kind of discharge injector electrode that is used for governing direct-current corona discharge smoke of claim 1, it is characterized in that said female pipe radius is 8-10mm.

3. according to a kind of discharge injector electrode that is used for governing direct-current corona discharge smoke of claim 1, the length that it is characterized in that said nozzle is 3-7mm.

4. according to a kind of discharge injector electrode that is used for governing direct-current corona discharge smoke of claim 1, the radius that it is characterized in that said nozzle is 2-4mm.

5. according to a kind of discharge injector electrode that is used for governing direct-current corona discharge smoke of claim 1, it is characterized in that said injector spacing is 15-25mm.

Images