Dielectric barrier discharge plasma auxiliary coal combustion generating device
Technical Field
The invention relates to the technical field of discharge plasma auxiliary combustion application, in particular to a generating device for dielectric barrier discharge plasma auxiliary coal combustion.
Background
The DBD plasma enhanced combustion is to generate a large number of active atoms and radicals through a plasma reaction zone to influence the chemical balance of a combustion process so as to accelerate the combustion process. Nowadays, more and more researchers are focusing on the development prospect of the plasma combustion-supporting technology.
The bottleneck problems of the conventional plasma combustion-supporting technology mainly focus on stable maintenance of reliable and uniform discharge, effective regulation of the types and the concentrations of high-energy active particles, acquisition of discharge plasma with corresponding parameters according to actual requirements and the like. Because the carbon-oxygen, carbon-carbon, carbon-hydrogen and other compound bonds in the coal are large, the initial voltage of discharge is high, and arc discharge is easy to occur, the temperature of a discharge contact is overhigh, and the limitation of electrode ablation and the like is further caused; with the progress of the coal combustion process, the change of factors such as the residual quality of coal, the stacking mode and the like can also influence the chemical reaction process of the combustion, such as the combustion temperature, the combustion speed, the product change and the like.
The existing research foundation of plasma-assisted coal combustion mainly comprises:
in the directional spinning plasma combustion-supporting system of the retrieval authorization notice number CN103953474B, a plasma combustion-supporting device capable of generating plasma with larger area and better uniformity is provided, a nanosecond pulse power supply is adopted as a power supply, and a pulse-modulated high-voltage alternating-current power supply is adopted to generate plasma.
The plasma coal burner of the search authorization publication No. CN103277792B provides an application example of a plasma coal combustion-supporting technology, which utilizes plasma to heat water vapor and coal powder, so that the combustion efficiency is improved. The invention utilizes active particles in DBD plasma to regulate and control the combustion process, and has essential difference in principle.
In summary, the existing plasma combustion-supporting technology has problems in the coal field, power supply application and cost estimation, and the processing object only contains coal dust, which greatly limits the wide application of the existing plasma combustion-supporting technology and device. Therefore, how to provide a generation device for coal combustion assisted by dielectric barrier discharge plasma is a problem to be solved urgently by those skilled in the art.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, one purpose of the invention is to provide a generating device for assisting coal combustion by dielectric barrier discharge plasma, which saves the expensive cost of vacuum equipment, adopts a porous screen electrode to bear the functions of gas inlet and outlet, and can generate stable and uniform plasma by combining a uniform gas flow mode; the chemical balance of the combustion system is influenced by using high-energy particles and active groups in the plasma, the combustion process of the system is regulated and controlled, and the effect is obvious.
The device for generating the dielectric barrier discharge plasma-assisted coal combustion is characterized by comprising an outer shell, a ground electrode lead and a high-voltage electrode lead, wherein the outer shell is arranged in a hollow mode, a first porous screen electrode is arranged on the upper end face of the outer shell, a second porous screen electrode is arranged on the lower end face of the outer shell, the ground electrode lead is fixed through a built-in nut and is embedded in the right side above the outer shell, the first porous screen electrode is connected with the ground electrode lead and is connected to a grounding end of a high-voltage alternating-current power supply, the high-voltage electrode lead is fixed through the built-in nut and is embedded in the bottom of the outer shell, and the second porous screen electrode is connected with the ground electrode lead and is connected to a terminal of the high-voltage alternating-current power supply.
Preferably, the first and second porous screen electrodes are arranged in parallel in the outer casing.
Preferably, all be provided with the buckle nut on first porous screen electrode and the porous screen electrode of second, be provided with the draw-in groove with buckle nut looks adaptation on the shell body, make first porous screen electrode and the porous screen electrode of second and form stable buckle fixed knot after the shell body embedding installation and construct, easily dismantle the change.
Preferably, the outer shell is made of an electrically insulating and high temperature resistant material, which includes polytetrafluoroethylene and ceramic.
Preferably, the first porous screen electrode and the second porous screen electrode both have a pore diameter of 3.0-5.0mm and a thickness of 0.8-1.5mm, and both the first porous screen electrode and the second porous screen electrode are of porous screen structures, so that the gas flowing function of a gas inlet and a gas outlet is directly realized, and coal ash and the like generated by full combustion after plasma treatment directly leaks into the bottom through the second porous screen electrode.
Preferably, the high-voltage alternating current power supply is a pulse-modulated sinusoidal alternating current power supply, the power of the high-voltage alternating current power supply is 800-2000W, the voltage peak-peak value is 0-60kV, the alternating frequency is 5-35kHz, the modulation pulse frequency is 10-1000Hz, and the duty ratio is 1-100% controllable, so that the over-high temperature of a contact caused by arc discharge is avoided, and the electrode ablation is prevented.
Preferably, the first porous screen electrode, the second porous screen electrode and the outer shell form a ventilation type discharge combustion chamber.
Preferably, lump coal is placed in the discharge combustion chamber to carry out DBD discharge and combustion.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the generating device for assisting coal combustion by dielectric barrier discharge plasma, the DBD plasma generating unit is formed by the screen electrode and coal, the structure is simple, the conception is exquisite, the gas circulation functions of the gas inlet and the gas outlet can be directly realized by the first porous screen electrode and the second porous screen electrode, the processing is carried out at normal temperature and normal pressure, the high cost of vacuum equipment can be saved, and the uniformity of generated plasma is good along with the adjustment of parameters such as voltage, frequency and modulation pulse frequency in the discharging process;
(2) according to the invention, the DBD discharge of the screen electrode is utilized, the discharge uniformity is good, and the generation of high-efficiency uniform atmospheric pressure DBD plasma rich in active particles is facilitated;
(3) the first porous screen electrode and the second porous screen electrode can be fixed, opened, closed and detached by utilizing the buckle nut structure, the fixing strength is ensured, and meanwhile, the fixing device is convenient to use, convenient to correct installation deviation, easy to replace and maintain, capable of being manufactured in a large scale and low in cost. The aperture of the second porous screen electrode is 3.0-5.0mm, and coal ash and the like generated by full combustion after plasma treatment can directly leak into the bottom through multiple holes, so that collection and treatment are convenient, and time and labor are saved;
(4) the coal of the invention acts as a dielectric in the electrode structure and can be considered to be quasi-stationary during the smoldering phase. With the advance of the coal combustion process, power supply excitation parameters such as voltage amplitude, alternating current frequency and the like, flowing wind speed and the like can be changed according to the change of factors such as the residual quantity of coal, the stacking mode and the like; the discharge uniformity of the DBD plasma and the type and concentration of high-energy active particles can be adjusted, the combustion process of coal is further regulated, the effectiveness of coal combustion treatment is ensured, the application range of a plasma combustion-supporting technology is widened, and the large-scale application prospect is wide.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic structural diagram of a device for generating dielectric barrier discharge plasma-assisted coal combustion according to the present invention;
fig. 2 is a schematic structural view of the porous screen electrode proposed in fig. 1 of the present invention.
In the figure: 1-outer shell, 2-first porous screen electrode, 3-second porous screen electrode, 4-snap nut, 5-ground electrode lead, 6-high voltage electrode lead, 7-high voltage alternating current power supply, 8-discharge combustion chamber.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
Referring to fig. 1-2, a device for generating dielectric barrier discharge plasma-assisted coal combustion, it is characterized in that the device comprises an outer shell 1, a ground electrode lead 5 and a high-voltage electrode lead 6, wherein the outer shell 1 is arranged in a hollow way, the outer shell 1 is made of materials with electric insulation and high temperature resistance, such as teflon, ceramic, the present invention preferably uses ceramic as the insulating material, but is not limited to the above materials, a first porous screen electrode 2 is arranged on the upper end surface of the shell, a second porous screen electrode 3 is arranged on the lower end surface of the shell, a ground electrode lead 5 is fixed through a built-in nut and is embedded on the right side above the shell 1, the first porous screen electrode 2 is connected with the ground electrode lead 5 and is connected with the ground end of a high-voltage alternating current power supply 7, the high-voltage electrode lead 6 is fixed by a built-in nut and is embedded at the bottom of the outer shell 1, and the second porous screen electrode 3 is connected to a high voltage electrode lead 6 and to a high voltage ac power supply 7 terminal.
The first porous screen electrode 2, the second porous screen electrode 3 and the outer shell 1 form a ventilation type discharge combustion chamber 8, blocky coal is placed in the discharge combustion chamber 8 to carry out DBD discharge and combustion, the coal is a quasi-steady existing process in the combustion process, and is a burned object and a dielectric medium, and low-temperature plasma is generated by dielectric barrier discharge and acts on the combustion process.
The invention applies DBD plasma to act on coal and forms flame plasma in the combustion process, and further acts with the flame plasma to reduce the discharge initial voltage, the DBD discharge is inevitably accompanied with a large amount of heat, the medium is generally damaged by the heat energy, and the invention takes the coal as the medium, can fully utilize the heat energy to assist combustion, reasonably and fully utilize the discharge advantage and improve the combustion efficiency.
The first porous screen electrode 2 and the second porous screen electrode 3 are both made of the same structural material, and the first porous screen electrode 2 and the second porous screen electrode 3 are arranged in parallel in the outer shell 1.
All be provided with buckle nut 4 on first porous screen electrode 2 and the porous screen electrode of second 3, the quantity that buckle nut 4 was applied to single porous screen electrode be 2-4, adopt stainless steel material or copper material, be provided with the draw-in groove with buckle nut 4 looks adaptation on the shell body 1, make first porous screen electrode 2 and the porous screen electrode of second 3 form stable buckle fixed knot structure with shell body 1 embedding installation back, be favorable to operations such as fixed, open, close, dismantlement.
The DBD plasma generating unit is formed by the screen electrodes and coal, the structure is simple, the conception is exquisite, the gas circulation functions of a gas inlet and a gas outlet can be directly realized by the structures of the first porous screen electrode 2 and the second porous screen electrode 3, the processing is carried out at normal temperature and normal pressure, the high cost of vacuum equipment can be saved, and the uniformity of generated plasma is good along with the adjustment of parameters such as voltage, frequency, modulation pulse frequency and the like in the discharging process.
The diameters of the first porous screen electrode 2 and the second porous screen electrode 3 are both 3.0-5.0mm, the thicknesses of the first porous screen electrode 2 and the second porous screen electrode 3 are both 0.8-1.5mm, the first porous screen electrode 2 and the second porous screen electrode 3 are both porous screen structures, the gas flowing function of a gas inlet and a gas outlet is directly realized, and coal ash and the like generated by full combustion after plasma treatment directly leak into the bottom through the second porous screen electrode 3.
The high-voltage alternating current power supply 7 is a power supply of the plasma generating device, can adjust voltage amplitude, power supply frequency, modulation pulse frequency and the like, and regulates and controls the combustion process rate by influencing the stable change of parameters. The high-voltage alternating current power supply 7 is a pulse-modulated sinusoidal alternating current power supply, the power supply power of the high-voltage alternating current power supply 7 is 800-2000W, the voltage peak-peak value is 0-60kV, the alternating current frequency is 5-35kHz, the modulation pulse frequency is 10-1000Hz, and the duty ratio is 1-100% controllable, so that the over-high temperature of a contact caused by arc discharge is avoided, and the electrode ablation is prevented.
The working principle is as follows: opening the first porous screen electrode 2, putting coal into a discharge combustion chamber 8, and then opening a high-voltage alternating current power supply 7 to start discharging, wherein the used power supply is a high-voltage high-frequency alternating current power supply for generating DBD plasma; a filamentous channel is generated at the beginning of discharge, uniform breakdown is only generated once in each half period of voltage, and discharge is gradually uniform along with the increase of voltage and frequency to form stable atmospheric glow discharge; in the propelling process of the combustion process, the type and concentration of high-energy active particles in the plasma can be adjusted by adjusting parameters such as the voltage amplitude, the alternating current frequency and the like of the high-voltage alternating current power supply 7; the medium is coal, the discharge region and the combustion region are in the same region, and the flame is also a plasma which is acted with the medium to reduce the discharge initial voltage during subsequent discharge, thereby being beneficial to dynamically adjusting the combustion-supporting efficiency of the plasma; meanwhile, DBD discharge can generate a large amount of heat energy, and the heat energy is applied to coal combustion in turn, so that coal energy is fully and reasonably applied, and the combustion efficiency is improved.
The generating device for assisting coal combustion by dielectric barrier discharge plasma provided by the invention works in a normal temperature and normal pressure environment, so that the expensive cost of vacuum equipment is saved, the porous screen electrode can bear the functions of gas inlet and outlet, and stable and uniform plasma can be generated by combining a uniform gas flowing mode; the chemical balance of the combustion system is influenced by using high-energy particles and active groups in the plasma, the combustion process of the system is regulated and controlled, and the effect is obvious.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.