METHOD FOR LOW-TEMPERATURE TRANSFORMATION OF DOMESTIC WASTE

Field of invention

The invention relates to methods of household waste management, in particular, to methods of disposing waste by plasma-chemical destruction method.

Prior art

There is a known method of solid organic waste treatment implemented in a device of patent RU2741004 (published on January 22, 2021), where solid organic waste is treated by vapor plasma gasification conversion with generation of syngas. The treatment is performed by a high-temperature plasma reactor, where water vapor is used as a plasma-supporting gas and temperature of reaction area is about 1600 to 2000 °C.

Disadvantages of this method are necessity of substantial heating for its carrying out and incomplete treatment of solid organic household waste, since the treatment results in syngas that also needs to be disposed. Moreover, non-organic substances contained in household waste cannot be treated this way.

Summary of invention

The invention is directed to attaining a technical effect of broadening range of technical solutions by providing a method of destruction of household waste at low temperature of treatment that is comparable to environment temperature.

This technical effect is attained by a destruction method, where household waste is fed into a reactor via an input opening, and entry of atmospheric air into the reactor is restricted. The reactor is provided in form of a closed cavity, which inner surface is made conductive entirely or partially and grounded. An electrode protrudes into the reactor, and this electrode is isolated from the grounded surface. High-voltage pulses are supplied to the electrode. The pulses cause formation of corona discharge streamers in a gap between the electrode and the conductive surface of the reactor.

According to document [1], a large number of streamers are formed near the electrode tip at each pulse. The streamers start multiplying and spreading towards the grounded conductive surface of the reactor cavity, gradually populating the inter-electrode gap and forming corona discharge. Plasma of corona discharge streamers exerts an effect on water contained in the loaded waste, thus causing formation of free radicals due to disintegration of water molecules H₂O → OH• + H•. In addition, other active substances are formed in the reactor due to corona discharge: O₃, O₂(a¹Δ), H₂O₂, OH, O(³P), NO, HNO₂ and HNO₃. Corona discharge also causes ultraviolet (UV) radiation. The above-mentioned active substances and UV radiation destroy any organic and inorganic substances contained in the household waste, thus providing complete destruction thereof and formation of harmless gaseous reaction products, namely, water and carbon dioxide. Non-organic contents of the household waste are destroyed by acids.Process of oxidation of organic substances in water is a chain reaction [2]. Low-rate chain reaction may be initiated by atmospheric oxygen and ozone. High-rate chain reaction is initiated by OH• radicals. In other words, plasma-chemical destruction of both organic and inorganic substances contained in the waste is provided by this method.

In one embodiment of the method, the conductive portion of the reactor cavity inner surface is covered by a layer of a water-containing liquid in advance, which facilitates formation of active particles inside the reactor.

Preferably, size of the gap between the electrode and at least one of conductive portions of the reactor cavity inner surface or surface of the water-containing liquid covering this portion is provided in range of 5 to 50 millimeters.

Preferably, the household waste is fed into the reactor in dosed amounts.

Preferably, the household waste doses are fed into the reactor in compressed form and entry of atmospheric air into the reactor is restricted.

Preferably, pressure inside the reactor is decreased by 0.1 to 1.0 Pa compared to atmospheric pressure.

In one embodiment of the method, depression is provided at the reactor output to decrease pressure inside the reactor.

Brief description of drawings

Fig. 1 shows a vertical cross-section of the reactor implementing the claimed method, where the following designators are used:

• 1 reactor body with inner cavity;
• 2 input opening;
• 3 output opening;
• 4 inner surface of reactor cavity;
• 5 conductive portions of inner surface of reactor cavity;
• 6 tipped electrode;
• 7 isolating members;
• 8 source of high-voltage pulses;
• 9 electrode tip;
• 10 conductive bottom of reactor;
• 11 device for dosed feeding waste to be treated;
• 12 electrostatic filter with extraction air fan providing depression at reactor output.

Detailed description of embodiments

The method is implemented by use of the reactor provided in form of the closed body (1) with the conductive bottom (10) that is grounded. The electrode (6) having the tip (9) protrudes into the body (1). The tip (9) is isolated from the conductive bottom (10) of the body (1) and directed towards it. A portion of compressed waste is fed from the device (11) for dosed feeding waste to be treated via the input opening (2) of the body (1), while entry of atmospheric air into the body (1) is restricted. High-voltage pulses are supplied to the electrode (6) from the source (8). As it is known from document [1], large number of streamers occur near the tip (9) of the electrode (6) with each pulse. The streamers start multiplying and spreading towards the conductive bottom (10) of the body (1), gradually populating the inter-electrode gap and forming streamer corona discharge. Plasma of corona discharge exerts an effect on water contained in the loaded waste and causes formation of free radicals upon destruction of water molecules: H2O → OH• + H•. In addition, other active substances are formed in the reactor due to corona discharge: O₃, O₂(a¹Δ), H₂O₂, OH, O(³P), NO, HNO₂ and HNO₃.Corona discharge also causes ultraviolet (UV) radiation. Almost entire energy of electrons in plasma is spent for formation of the indicated active particles by dissociation, activation of electron states and creation of rotation and oscillation levels of gas resided in the reactor, where streamer corona discharge is formed, so no substantial gas heating occurs. The above-mentioned active substances and UV radiation destroy any organic and inorganic substances contained in the waste to be treated, thus providing complete destruction thereof and formation of harmless gaseous reaction products, namely, water and carbon dioxide. Non-organic contents of the waste are destroyed by acids. Process of oxidation of organic substances in water is a chain reaction [2]. Low-rate chain reaction may be initiated by atmospheric oxygen and ozone. High-rate chain reaction is initiated by OH• radicals. In other words, plasma-chemical destruction of both organic and inorganic substances contained in the waste is provided in the device. Temperature of the body (1) and gases leaving it via the output opening (3) is near the environment temperature. In fact, entire energy of electric pulses is spent for formation of the active particles, which substantially accelerate natural reactions of oxidation of household waste. Gaseous products of destruction enter the output opening (3) of the reactor.

Thus, the specified technical effect is attained in form of providing the method of plasma-chemical destruction of both organic and non-organic substances contained in household waste at a temperature near the environment temperature.

1. [1] H.A., .M., A.B., B.., Γ.M., C.. B //. 2004. T. 78. 7. C. 1326-1331. (Aristova N.A., Piskarev I.M., Ivanovskiy A.V., Selemir V.D., Spirov G.M., Shlepkin S.I. Initiation of chemical reactions by electrical discharge in dielectric-gas-liquid configuration// Physical Chemistry Journal, 2004, Vol. 78, #7, pages 1326-1331.)
2. [2] .M B , // . 2001. T. 71. . 10. C. 1622. (Piskarev I.M. Oxidation-reduction processes in water initiated by electrical discharge above water surface // General Chemistry Journal, 2001, Vol. 71, Issue 10, page 1622.)