RU2230984C2 - Method of burning fuel in furnace facility - Google Patents

Abstract

FIELD: creating acoustic action on combustion process in furnace facility.

SUBSTANCE: proposed method includes creating acoustic action on fuel combustion process in high-frequency pulsating mode at high-frequency component of 25-160 kHz and pulsation of 5-240 Hz. Proposed method intensifies and optimizes combustion process due to smooth mixing of oxidizer with fuel accelerating oxidizing processes and reducing incomplete combustion by 40-50% as compared with known method.

EFFECT: enhanced efficiency.

3 dwg

Description

The invention relates to the field of energy and can be used to implement acoustic effects on the process of burning fuel in a furnace device.

There are various methods of burning fuel in a furnace device (solid, dusty, liquid, gaseous), including both preliminary grinding of fuel into fine powder and concentrated air supply to the furnace space (see G.S. Bobrovsky, A.M. Zimakov. “Steam boilers of industrial enterprises”, State Power Publishing House, M.-L .: State Power Publishing House, 1949, pp. 97-126).

The disadvantages of the known methods are the low efficiency of fuel combustion due to chemical and mechanical burns due to uneven mixing of the oxidizing agent with the fuel.

There is also known a method of burning fuel by the influence of acoustic vibrations in the combustion zone, while simultaneously with acoustic vibrations in the combustion zone, vibrations of a nonlinear, mainly sawtooth, shape with a frequency of 10-100 times higher than the frequency of acoustic vibrations are excited, and the ratio of their amplitudes is 0.2 -1.0 (see the description of the invention to ed. St. Petersburg No. 663966, M. Cl. ² F 23 D 11/34 on “Method of burning fuel”).

This technical decision was made as a prototype.

Using this method allows to increase the efficiency of fuel combustion by superimposing low-frequency acoustic vibrations on nonlinear vibrations with a steep front at the peak pressure and high frequency, which, in turn, allows you to increase both the heat transfer and dispersion of fuel particles, and creates the necessary amplitude of movement particles of fuel.

However, the nonlinear interaction of low and high-frequency acoustic waves with a steep front at the peak of pressure leads to insufficiently uniform mixing of the oxidizing agent with the fuel, the process of burning fuel particles is unstable, which does not allow it to be optimized to the full size range of particles of the burned fuel and creates conditions for particle burning fuel.

The objective of the proposed technical solution is to create a method of burning fuel, which allows to intensify, optimize this process due to more uniform mixing of the oxidizing agent with fuel and increase the speed of oxidation processes.

The problem is achieved in that in a method of burning fuel in a furnace device, which includes an acoustic effect on the fuel combustion process, the acoustic effect is carried out in a high-frequency pulsating mode with a high-frequency component of 25-160 kHz with a pulsation of 5-240 Hz.

It is known that during the combustion of fuel, in particular coal dust, small particles (up to 100 microns) and volatile substances burn quickly and consume the bulk of oxygen up to 96% of the amount supplied to the furnace, while large and medium dust particles (300 -100 μm), which determine mechanical underburning, burn in an oxygen-poor atmosphere (4% or less), as a result of which the rate of oxidized processes decreases accordingly. In addition, the high porosity of the surface with a significant mass of such a dust gives it a high windage, creating its synchronous movement with the gas stream along the length of the flame and the furnace space, and further reduces the speed of diffusion-oxidation processes.

The acoustic effect on the fuel combustion process with a high-frequency component of 25-160 kHz with a pulsation of 5-240 Hz allows to increase the efficiency of fuel combustion and to intensify the combustion process of the entire size range of fuel particles (in particular, coal dust, fuel oil aerosols) by creating a frequency range corresponding to natural frequencies of the vibrations of the fuel particles, leading to a resonant effect, which causes an increase in the amplitudes of the vibrations of the fuel particles exceeding the size of the groups of formations of near-boundary inert gases being products of oxidation, and thereby increases the likelihood of collision with oxygen.

The specified acoustic exposure parameters provide the particles of the fuel with relative pulsed gas flow relative to the pulsed regime, which is necessary for particles to escape from the caron cloud of oxidation products (where oxygen is practically absent), which increases the likelihood of collisions with free oxygen molecules of the entire particle size range and reduces underburning more than 30-50% compared with the known solution - the prototype.

Under acoustic exposure with a high-frequency component of less than 25 kHz with a pulsation of less than 5 Hz, complete combustion of the fuel is not ensured due to the uneven mixing of the oxidizer with the fuel.

Acoustic impact with a high-frequency component of more than 160 kHz with a pulsation of more than 240 Hz is economically and technically impractical due to the achievement of the required heat-physico-chemical characteristics in the combustion device under the stated modes and the subsequent rise in price and complication of the method of burning fuel. Moreover, with pulsations of more than 240 Hz, the necessary low-frequency component is not provided.

The method is as follows.

For example, a diagram of the mode (operation) of the method is shown in the drawing: position 1 — high-frequency oscillations, position 2 — pulsating mode, a — medium frequency characteristics (high-frequency — 90 kHz with 120 Hz pulsation), b — minimum high-frequency and maximum pulsating modes (high-frequency - 25 kHz with a ripple of 240 Hz), in - the maximum high-frequency and minimum pulsating modes in the specified parameters (high-frequency - 160 kHz with a ripple of 5 Hz).

Depending on the quantitative ratios of the size scales of large and small particles, combinations of high and low frequencies may be different, more optimal for a particular option.

The method of burning fuel (coal dust, gas) was carried out in boilers TP-92 of Perm GRES-16.

The test results showed that the use of the claimed method of burning fuel allows you to intensify, optimize this process and reduce the underburning in comparison with the known prototype method by 40-50%.

When going beyond the declared modes, either underburning of the fuel (high-frequency component of less than 25 kHz with a ripple of less than 5 Hz) is observed, or it remains at the level of the claimed modes (high-frequency component of more than 160 kHz with a ripple of more than 240 Hz).

Claims (1)

A method of burning fuel in a furnace device, including acoustic impact on the fuel combustion process, characterized in that the acoustic impact is carried out in a high-frequency pulsating mode with a high-frequency component of 25-160 kHz with a pulsation of 5-240 Hz.