RU2473669C1 - Method to gasify solid fuel - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: method to gasify solid fuel consists in supplying fuel into a gas generator volume, its pyrolysis and gasification with subsequent treatment of the produced generator gas from moisture, resin and non-gasified remains of solid fuel. Treatment is carried out in the inner volume of the gas generator by exposure to ultrasonic oscillations with frequency of more than 20 kHz and intensity in the range of 130-145 dB. Oscillations are developed by a flat emitter of round or rectangular shape, oscillating when bent at the frequency, which is multiple to the main one. The emitter is excited with a longitudinally oscillating piezoelectric converter supplied with an electronic generator of ultrasonic frequency, which is placed outside the gas generator, but is acoustically connected to it. Exposure is simultaneously carried out by oscillations developed by both sides of the flat emitter, besides, oscillations developed by the emitter side, which is reverse to the inner volume of the gas generator, are sent into the gas generator volume after reflection and passing of the distance exceeding the longitudinal size of the emitter by the value multiple to the half of the length of emitted ultrasonic oscillations in air.

EFFECT: invention makes it possible to reduce carryover of resin, water vapours and non-gasified remains of solid fuel.

2 dwg

Description

The invention relates to a power system, chemical and fuel industry, can be used for gasification of solid fuel or mixtures of organic substances.

In recent years, an increasing role of local fuel and combustible waste in the country's energy supply has been characteristic. This is due to the fact that in the structure of the cost of production, the energy component is predominant. Therefore, taking into account the sharp rise in price and the shortage of high-calorie energy sources based on oil and natural gas, the need arose to create technologies and equipment for generating heat and electricity based on renewable and local fuels (wood processing waste, agricultural production, industrial waste, etc. .), the cost of which is currently about 10-12 times lower than the cost of petroleum products [1].

One of the effective directions of using solid fuels and combustible wastes in industrial and agricultural production in the energy sector is, in addition to direct burning in furnaces, their preliminary processing into combustible gases for various purposes using gas generators. The gas obtained in gas generators can be used as fuel in power plants, technological processes, transport and stationary power machines.

To date, a large number of different methods of gasification of solid fuel have been developed (depending on the purpose of the gas obtained, the quality of the initial fuel, the type of blast, pressure, etc.) and the designs of gas generators that implement them [2].

The advantages of generator gas are the ability to maintain high-temperature processes, the best combustion conditions and process control, as well as the possibility of its production from low-grade and non-deficient types of solid fuel, including solid industrial or household waste.

Unfortunately, one of the main disadvantages of existing methods of gasification of solid fuels is the significant content of tar, moisture and soot in the resulting combustible gas. This makes the resulting gas unsuitable for pumping through pipelines, as a fuel for internal combustion engines (for example, electric generators).

Known methods of gasification aimed at eliminating this drawback by choosing the optimal type of fuel (giving a relatively clean gas) in the form of coke or charcoal. This method of gasification significantly increases the cost of the produced gas and makes the process of its production economically disadvantageous.

Partially, the problem of eliminating the high content of impurities in the generator gas is solved in the method of gasification of solid fuel, adopted as a prototype [3].

The method of gasification adopted as a prototype consists in supplying fuel to the gas generator, its pyrolysis and gasification, followed by purification of the generated generator gas from moisture, resin and non-gasified solid fuel residues. Gas purification is carried out outside the gas generator using a separator (for example, a cyclone or scrubber).

The method adopted for the prototype, allows the process of generating generator gases and reduces the content of foreign impurities in them, however, it is characterized by a number of significant disadvantages:

- low cleaning efficiency of the generator gas, due to the resin present in the generator gas, which together with soot adheres to the walls of the equipment, and causes clogging of the gas cleaning modules;

- corrosion of gas pipelines due to the high humidity of the produced gas;

- the inability to use the cheapest types of solid fuel - waste of plant origin (straw, energy crops) or municipal solid waste, characterized by a significant removal of ash from the gas generator;

- the need for periodic maintenance of gas cleaning modules;

- increased weight and size characteristics of the equipment due to the use of external gas cleaning modules.

The proposed technical solution is aimed at eliminating the disadvantages of the prototype and creating a new method of gasification of solid fuel, which has increased efficiency due to the almost complete elimination of the removal of resin, water vapor and non-gasified residues of solid fuel from the active part of the gas generator.

The proposed method of gasification of solid fuel consists in supplying fuel to the volume of the gas generator, its pyrolysis and gasification, followed by purification of the generated generator gas from moisture, resin and non-gasified solid fuel residues.

In this case, the purification of the generator gas is carried out in the internal volume of the gas generator by the action of ultrasonic vibrations with a frequency of more than 20 kHz and an intensity in the range of 130-145 dB. Oscillations are created by a flat emitter of round or rectangular shape, flexurally oscillating at a frequency multiple of the main one and excited, placed outside the gas generator, acoustically connected to it by a longitudinally oscillating piezoelectric transducer fed by an ultrasonic frequency electronic generator [4].

The exposure is carried out simultaneously by oscillations created by both sides of the flat emitter, and the oscillations created by the emitter side opposite to the internal volume of the gas generator are sent to the gas generator volume after reflection and passage of a distance exceeding the longitudinal size of the emitter by an amount multiple of half the wavelength of the emitted ultrasonic vibrations in air.

In the proposed method of gasification of solid fuel, the task of increasing the efficiency of generating gas is solved by:

- purification of the obtained gases from dispersed impurities (carbon black, resin) by coagulation [5] and precipitation by ultrasonic vibrations directly in the gas generator;

- return of coagulated impurities under the action of gravity to the active zone of the gas generator for further gasification, up to complete decomposition;

- Acoustic intensification of the chemical processes of oxidation and reduction occurring in the active zone of the gas generator.

An additional advantage of using acoustic coagulation is the ability to build a gas generator according to the simplest direct-flow scheme.

The essence of the technical solution is illustrated in figure 1, which schematically shows the design of a gas generator that implements the proposed method. The gas generator consists of a metering hopper 1, which supplies solid fuel to the active zone of the gas generator 2, a nozzle for exhausting the generator gas 3. In the upper part of the gas generator there is an acoustic emitter 4 in the form of a flat plate of a round or rectangular shape, bending vibrating at a frequency that is a multiple of the main one. The oscillations of the emitter are excited placed outside the gas generator, but acoustically connected to it by a longitudinally oscillating piezoelectric transducer 5, fed by an ultrasonic frequency electronic generator (not shown in FIG. 1).

The top cover of the gas generator is a reflector 6, installed in such a way that ultrasonic vibrations created by the emitter side opposite to the internal volume of the gas generator are directed to the gas generator volume after reflection and passage of a distance exceeding the longitudinal size of the emitter by a multiple of half the wavelength of the emitted ultrasonic vibrations in air .

The acoustic impact parameters (frequency of more than 20 kHz, intensity in the range of 130-145 dB) were selected based on the condition of ensuring maximum coagulation efficiency (cavitation destruction of the combined solid and liquid particles is possible at high intensities) and the implementation of safe process conditions for service personnel.

Figure 2 shows photographs illustrating (confirming) a decrease in the removal of resins and dispersed particles from the gas generator when exposed to ultrasonic vibrations using an ultrasonic emitter with a diameter of 190 mm (installed inside the gas generator), excited by a piezoelectric transducer (placed outside the gas generator housing). The photo of FIG. 2a corresponds to the gasification process without ultrasonic exposure, FIG. 2b - to ultrasonic exposure with a sound pressure level of 130 dB, FIG. 2b - to ultrasonic exposure of 145 dB. The experiments showed high efficiency of the proposed method of gasification of solid fuel (reduction of tar by 9 times, dispersed impurities - non-gasified residues of solid fuel by 26 times, water vapor by 7 times).

The practical implementation of the proposed technical solution is planned for implementation by the Center for Ultrasonic Technologies LLC in 2012.

List of literature used in the preparation of the application

1. A.V. Keiko, Prospective gasification regimes for low-grade solid fuel [Text] Keiko A.V., Shirkalin I.A., Svishchev D.A. // Promising modes of gasification of low-grade solid fuel. Proceedings of the Russian Academy of Sciences. Energy 2006. No3. S.55-63.

2. VVAfanasyev, Analysis of solid fuel gasification technologies [Text] Afanasyev VV, Kovalev VG, Tarasov VA // Bulletin of the Chuvash University. 2010. No3. S.194-205.

3. RF patent 1496246 - prototype

4. VNKhmelev, Development of piezoelectric ultrasonic oscillatory systems for intensification of processes in gases [Text] VNKhmelev, SNTsyganok, AVShalunov, ANLebedev, SSKhmelev, ANGalakhov // Proceedings of the Tula State University, vol. 1: Tula State University, pp. 10, 2010.

5. V.N. Khmelev, ultrasonic coagulation of aerosols [Text] / V.N. Khmelev, A.V. Shalunov, K.V.Shalunova, S.N. Tsyganok, R.V. Barsukov, A.N.Sleveen // Alt. state, tech. University, BTI. - Biysk Univ Alt. state, tech. Press, 2010 .-- 241.

Claims (1)

The method of gasification of solid fuel, which consists in supplying fuel to the volume of the gas generator, its pyrolysis and gasification with subsequent purification of the generated generator gas from moisture, tar and non-gasified solid fuel residues, characterized in that the cleaning is carried out in the internal volume of the gas generator by the action of ultrasonic vibrations with a frequency of more than 20 kHz and an intensity in the range 130-145 dB created by a flat emitter of round or rectangular shape, flexurally oscillating at a frequency multiple of the main and excited, located outside the gas generator, but acoustically connected to it by a longitudinally oscillating piezoelectric transducer fed by an ultrasonic frequency electronic generator, the action is carried out simultaneously by oscillations created by both sides of the flat emitter, and the oscillations created by the emitter side opposite to the internal volume of the gas generator are sent to the gas generator volume after reflection and passage of a distance exceeding the longitudinal size of the emitter by an amount multiple half the wavelength of the emitted ultrasonic vibrations in the air.

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