CN111486476A - A New Intelligent Suppressor of Combustion Instability - Google Patents

Abstract

The invention discloses a novel intelligent suppressor for unstable combustion, which belongs to the field of combustion.A control system is used for sampling oscillation pressure generated by unstable combustion in real time, analyzing oscillation dominant frequency of the oscillation pressure in real time and rapidly, and then outputting an adjusting signal through a stepping motor; the sealing piston in the sound absorption pipeline is connected with the precise screw rod, the rotary lifting component is utilized to adjust the up-and-down movement of the sealing piston through rotation, and a gear arranged outside the rotary lifting component and the stepping motor form a gear transmission mechanism, so that the position of the sealing piston in the sound absorption pipeline can be adjusted through the stepping motor, and the working frequency of the sound absorption pipeline is adjusted; the invention ensures that the suppressor has a larger working frequency range, can ensure the optimal suppression effect and solves the problems of single control frequency and narrower working frequency band of the traditional combustion unstable passive controller.

Description

A New Intelligent Suppressor of Combustion Instability

technical field

The invention belongs to the field of combustion, and relates to a combustion instability suppressor, in particular to a novel combustion instability intelligent suppressor.

Background technique

In recent years, people have gradually paid attention to the issue of low-pollution emissions from combustion, and lean-fuel combustion technology has great development potential in reducing emissions, but this makes fuel combustion more sensitive to acoustic disturbances and prone to combustion instability. Combustion instability occurs widely in combustion systems such as gas turbine combustors, rocket engines, and boilers. The sound wave disturbance generated by the combustion flame, etc., is reflected by the system boundary and reaches the flame position to further interfere with the flame. When the flame heat release pulsation and the sound wave are in the same phase (the phase difference is less than 90°), the two are coupled and driven each other, resulting in a relatively high amplitude. Large oscillating sound waves, which not only increase the risk of flameout, but also cause severe structural damage to the combustion system.

To sum up, the combustion instability is caused by the mutual coupling between the sonic pulsation and the flame pulsation. Therefore, different scholars have studied different control methods to reduce the heat release pulsation, and at the same time, reduce the risk of combustion instability by absorbing the sonic energy or Reduce the pulsation amplitude of the oscillating pressure. The control methods for combustion instability are mainly divided into active control and passive control. In the active control of combustion instability, the control system inputs control energy into the combustion system through the actuator (high-frequency solenoid valve or speaker, etc.) according to the sampled oscillating pressure signal to interfere with the sound wave or flame; while in the passive control of combustion instability, the There is no need to input additional energy into the controlled system, and the characteristics of the original system are often changed due to the addition of passive controllers, so that the combustion instability of the original system is eliminated or weakened.

A typical passive controller for combustion instability is a Helmholtz resonator, which consists of a short tube and an acoustic cavity. Has an absorbing effect on the oscillating pressure, thereby reducing the oscillating intensity of combustion instability. However, Helmholtz resonators or other sound-absorbing structures have many disadvantages in suppressing combustion instability, such as their single operating frequency and narrow operating frequency bandwidth. When the oscillation frequency of the combustion system is slightly different from the resonant frequency of the resonator When the deviation is exceeded, the control effect is obviously deteriorated. Therefore, the in-depth study of the passive controller with unstable combustion, such as how to expand its operating frequency bandwidth to make it have a wider range of adaptation, has become a research hotspot.

SUMMARY OF THE INVENTION

The invention is based on the development idea of the passive controller in the prior art, and discloses a novel combustion instability intelligent suppressor, which is mainly composed of a sound absorption pipe with an adjustable end and a control system. The control system intelligently adjusts the position of the piston at the end of the wavelength tube through real-time monitoring of the oscillating pressure generated by combustion instability, thereby increasing its working frequency range, solving the problems of single control frequency and narrow working frequency band of the traditional combustion instability passive controller.

The present invention is realized in this way:

A novel combustion instability intelligent suppressor, the suppressor comprises a sound-absorbing pipe and an oscillating pressure sensor respectively arranged on the wall of the combustion device, a sealing piston is movably arranged inside the sound-absorbing pipe, and the sealing piston is connected to the combustion chamber. The distance from the wall of the device is the working length of the sound absorption pipe; the invention absorbs the oscillating pressure wave generated by combustion instability through the sound absorption pipe, the sealing piston in the sound absorption pipe plays a sealing role, and the distance from the sealing piston to the bottom is the working length.

One end of the sound-absorbing pipe is connected to the combustion system, and the actual working length of the sound-absorbing pipe can be adjusted, which is adjusted in real time by the control system online. By adjusting the position of the sealing piston in the sound absorption pipe so that its resonance frequency is consistent with the main frequency of the oscillating pressure in an unstable combustion environment, the oscillating pressure can be better absorbed. The suppressor combines passive and active methods. The movement of the piston is completed by the control system. The control system samples the oscillating pressure, analyzes the oscillation frequency of unstable combustion, and further moves the piston to a reasonable position through the execution structure.

A precision lead screw is arranged on the sealing piston, and a transmission device is arranged at the top of the sound-absorbing pipe. The precision lead screw is connected with the transmission device. The transmission device includes a rotating and lifting component. The components are connected, and the rotating lifting component is provided with a stepping motor outside; through the rotation of the stepping motor, the rotating lifting component is driven to control the movement of the precision lead screw, thereby controlling the movement of the sealing piston, and adjusting the working length of the sound absorption pipe.

Further, the working length of the sound-absorbing pipe is adjusted by the movement of the sealing piston; the diameter of the sound-absorbing pipe is between 10 and 50 mm; the sound-absorbing pipe is provided with a constant temperature air inlet at the bottom. The constant temperature air inlet is installed at the bottom end of the sound absorption duct, and this position does not affect the piston. The air introduced into the sound-absorbing pipe can be ambient air or other gas with stable temperature. It is mainly to maintain a stable temperature environment in the sound-absorbing pipe. Therefore, the working length of the sound-absorbing pipe is linearly corresponding to the frequency of the sound waves it absorbs. relation.

Further, the rotating lifting component is provided with a gear outside, and the gear is connected with the stepping motor. Gears are installed on the outside of the rotating lifting part, so that the gears and the stepping motor are driven by the gears, which facilitates the flexible rotation of the rotating lifting parts and facilitates transmission control. The structural design of the transmission device in the suppressor makes the angular rotation of the stepper motor change into the positional movement of the piston in the sound-absorbing pipe. In addition, the gear is installed outside the rotating lifting component, and the rotating lifting component is connected with the sound absorption pipe through the bearing. This structure design facilitates the procurement and processing of the components, and at the same time ensures the simplicity and reliability of the installation.

Further, the rotating lifting component and the precision lead screw are connected by threads, wherein the rotating lifting component and the precision lead screw are connected by threads, and when the rotating lifting component rotates, the precision lead screw drives the sealing piston to move up and down; the rotating The lifting part is installed and connected with the sound absorption pipe through the bearing.

Further, an oscillating pressure measuring pipe is arranged on the wall surface of the combustion device, and the oscillating pressure sensor is isolated from the wall surface of the combustion device by arranging an oscillating pressure sensor at the top of the oscillating pressure measuring pipe. Since the long-term temperature resistance of the sensor is limited, it is necessary to design an oscillating pressure measurement pipeline to isolate the oscillating pressure sensor from the wall of the combustion device, so as to avoid the oscillating pressure sensor from being damaged by high temperature.

Further, the stepping motor and the oscillating pressure sensor are respectively connected to one end of the data acquisition card, and the other end of the data acquisition card is connected to the control system.

The core idea of the present invention is to apply the active control idea to the passive control mechanism, so that the acoustic wave absorbing pipe can have a more flexible adjustment scheme. The working length of the sound absorption pipe can be adjusted according to the main frequency of unstable combustion within a certain range, so that it has the characteristics of online real-time intelligent adjustment. When the main frequency of the unstable combustion oscillation changes, the control system can quickly adjust the sound absorption pipe. Working length to ensure optimal sound absorption.

The beneficial effects of the present invention compared with the prior art are:

The suppressor of the present invention can be easily installed on the wall surface of the combustion system, as long as there is an appropriate space outside the combustion system, and this method does not cause great geometric damage to the combustion system; after the control system samples and analyzes the oscillating pressure , quickly adjust the position of the piston at the end of the suppressor, which enables the suppressor to track the oscillation frequency of unstable combustion in real time, and solves the problem of single frequency and narrow frequency band in traditional passive control. The control system ensures that the resonant frequency of the suppressor is consistent with the unstable combustion in real time, which makes the suppressor have the best sound absorption effect. burning disturbance;

The invention proposes a sound absorption pipe with an adjustable end to suppress combustion instability. The control system intelligently adjusts the position of the end piston according to the sampling pressure. Combining passive control and active control, the oscillating pressure can be monitored online in real time, which makes passive control The operating frequency of the device can be adjusted arbitrarily within a certain range. The experimental results also confirm that the combustion instability intelligent suppressor can effectively reduce the pulsation amplitude of the oscillating pressure, and can be applied to the combustion system to suppress the combustion instability, and can effectively reduce the oscillation intensity of the combustion instability.

Description of drawings

1 is a schematic structural diagram of a novel combustion instability intelligent suppressor of the present invention;

Fig. 2 is a partial enlarged view of the combustion instability intelligent suppressor of the present invention;

Among them, 1-burning device wall, 2-constant temperature air inlet, 3-sound absorbing pipe, 4-sealing piston, 5-bearing, 6-gear, 7-rotating lifting part, 8-precision screw, 9-stepping Motor, 10-control system, 11-data acquisition card, 12-oscillating pressure sensor, 13-oscillating pressure measuring pipeline.

Detailed ways

In order to make the objectives, technical solutions and effects of the present invention clearer and clearer, the following examples are given to further describe the present invention in detail. It should be pointed out that the specific implementations described herein are only used to explain the present invention, but not to limit the present invention.

As shown in Figures 1-2, the intelligent suppressor of combustion instability designed by the present invention mainly consists of a sound absorption pipe 3, a sealing piston 4, a transmission device, a stepping motor 9, an oscillating pressure sensor 12, an oscillating pressure measuring pipe 13 and a control system etc. composition. Combustion is usually confined to an enclosed space, such as the furnace in a boiler, and the combustion chamber in a gas turbine. Therefore, the wall surface 1 of the combustion device in the present invention represents the wall surface of a combustion device in which combustion instability occurs, and may be the furnace wall surface or the combustion chamber wall surface in practice. The sound absorption pipe 3 designed in the present invention plays the role of absorbing the oscillating sound waves generated by unstable combustion, and its diameter can be designed within a certain range, for example, within the range of 10-50 mm, and can also be adjusted according to the actual effect. Its principle is the same as that of a quarter-wavelength tube, that is, when the length of the pipe (one end is open and one end is closed) is equal to a quarter of the wavelength of the sound wave, the pipe can absorb the sound wave.

A sealing piston 4 is movably arranged inside the sound absorption pipe 3 of the present invention, and the distance from the sealing piston 4 to the wall surface 1 of the combustion device is the working length of the sound absorption pipe 3 . The sealing piston 4 is provided with a precision lead screw 8, the top of the sound absorption pipe 3 is provided with a transmission device, and the precision lead screw 8 is connected with the transmission device; the control system 10 is connected outside the transmission device; The transmission device includes a rotating lifting member 7, the precision screw 8 is connected with the rotating lifting member 7, and the rotating lifting member 7 is provided with a stepping motor 9 outside; the rotation of the stepping motor 9 drives the rotating lifting member 7. Control the movement of the precision lead screw 8, and then control the movement of the sealing piston 4, and adjust the working length of the sound absorption pipe 3.

In the present invention, the sealing piston 4 and the control transmission system are introduced into the suppressor, so that the working length of the pipeline can be easily adjusted, so that it has the ability to absorb sound waves of various frequencies. In order to facilitate the movement of the sealing piston 4, a precision lead screw 8 is connected to it, and the movement of the precision lead screw 8 is controlled by a transmission device.

In the transmission device of the present invention, the rotary lifting member 7 is connected with the precision screw 8 through threads. When the rotary lifting member 7 rotates, the precision screw 8 drives the sealing piston 4 to move up and down. At the same time, the rotating lifting member 7 is installed with the sound absorption pipe 3 through the bearing 5 , which facilitates the flexible rotation of the rotating lifting member 7 . In order to facilitate transmission control, a gear 6 is installed on the outside of the rotating lifting member 7, so that the gear 6 and the stepping motor 9 are driven by gear cooperation. The detailed structure is shown in FIG. 2 . When the stepping motor 9 rotates, the sealing piston 4 in the sound-absorbing pipe 3 moves, so that the working length of the sound-absorbing pipe 3 can be adjusted by the stepping motor 9 .

The working frequency of the sound-absorbing pipe 3 in the present invention is determined by its working length, and needs to be calculated according to the temperature of the air medium in the sound-absorbing pipe 3, and the high-temperature gas in the combustion device is inevitably introduced during the movement of the sealing piston 4 into the sound absorbing duct, which will change the operating frequency of the sound absorbing duct 3. Therefore, a constant temperature air inlet 2 is provided at the bottom end of the wall surface 1 of the combustion device close to the sound absorption pipe 3, and a small amount of constant temperature air or nitrogen is introduced into the sound absorption pipe. On the one hand, it can cool the sound absorption pipe and prevent Working for a long time causes the temperature of the sound-absorbing pipe to increase and changes the working frequency; on the other hand, it can prevent the inhalation of high-temperature gas due to the movement of the piston. The present invention inputs a medium of constant temperature, such as air or nitrogen, into the sound absorption pipe. Any sound-absorbing structure needs to calculate the frequency of the sound wave it absorbs based on the temperature of the medium. In order to avoid the inhomogeneity and uncertainty of the gas temperature in the sound-absorbing pipe, it is necessary to introduce a medium of constant temperature into the sound-absorbing pipe, which is fixed. The temperature of the medium in the sound-absorbing pipe of the suppressor makes the working frequency of the suppressor have a linear correspondence with the rotation angle of the stepping motor.

The stepping motor 9 in the present invention has a precise rotation angle and is widely used in transmission. The stepper motor 9 is controlled by the control system 10, and the working length of the sound absorption pipe 3 is adjusted according to the main oscillation frequency of unstable combustion, which is obtained by sampling and analysis of the oscillation pressure. Since the long-term temperature resistance of the general sensor is limited, it is necessary to design the oscillating pressure measuring pipe 13 to isolate the oscillating pressure sensor 12 from the wall surface 1 of the combustion device, so as to prevent the oscillating pressure sensor 12 from being damaged by high temperature. The oscillating pressure sensor 12 converts the oscillating pressure signal into an electrical signal, and then collects data through the control system 10 through the data acquisition card 11, and performs spectrum analysis on the oscillating pressure signal by means of spectrum analysis, such as Fourier transform, to obtain unstable combustion oscillations. frequency. The control system 10 of the present invention obtains the oscillation main frequency of unstable combustion by analyzing the sampled oscillation pressure, and then the control system adjusts the sound-absorbing pipe to a suitable working length through the stepping motor, so as to ensure that the sound-absorbing pipe can adjust the working length in real time, so as to realize Combustion instability is suppressed in real time.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, some improvements can be made without departing from the principles of the present invention, and these improvements should also be regarded as the present invention. the scope of protection of the invention.

Claims (6)

1. The novel intelligent suppressor for unstable combustion is characterized by comprising a sound absorption pipeline (3) and an oscillation pressure sensor (12) which are respectively arranged on a wall surface (1) of a combustion device, wherein a sealing piston (4) is movably arranged in the sound absorption pipeline (3), and the distance from the sealing piston (4) to the wall surface (1) of the combustion device is the working length of the sound absorption pipeline (3);

a precise lead screw (8) is arranged on the sealing piston (4), a transmission device is arranged at the top end of the sound absorption pipeline (3), and the precise lead screw (8) is connected with the transmission device; the control system (10) is connected outside the transmission device;

the transmission device comprises a rotary lifting component (7), the precision lead screw (8) is connected with the rotary lifting component (7), and a stepping motor (9) is arranged outside the rotary lifting component (7); the rotation of the stepping motor (9) drives the rotary lifting component (7) to control the movement of the precision screw rod (8), so as to control the movement of the sealing piston (4) and adjust the working length of the sound absorption pipeline (3).

2. A new type of intelligent suppressor of combustion instability as defined in claim 1, characterized in that the working length of the sound-absorbing duct (3) is adjusted by the movement of the sealing piston (4); the diameter of the sound absorption pipeline (3) is 10-50 mm; the bottom of the sound absorption pipeline (3) is provided with a constant temperature air inlet (2).

3. A new type of intelligent suppresser for combustion instability as defined in claim 1, characterized in that said rotary elevating member (7) is externally provided with a gear (6), and is connected with a stepping motor (9) by means of the gear (6).

4. The novel intelligent suppressor of combustion instability as set forth in claim 1, characterized in that the rotary elevating member (7) is connected with the precision lead screw (8) by a screw thread; the rotary lifting component (7) is connected with the sound absorption pipeline (3) through a bearing (5).

5. The novel intelligent suppressor for combustion instability as recited in claim 1, characterized in that the combustion device wall (1) is provided with an oscillating pressure measuring pipe (13), and the oscillating pressure sensor (12) is isolated from the combustion device wall (1) by arranging the oscillating pressure sensor (12) at the top end of the oscillating pressure measuring pipe (13).

6. The novel intelligent suppressor of combustion instability as set forth in claim 1, characterized in that the stepping motor (9) and the oscillating pressure sensor (12) are respectively connected to one end of a data acquisition card (11), and the other end of the data acquisition card (11) is connected to the control system (10).

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