RU2287139C1 - Device for combined acoustic-aerodynamic protection of objectives of thermal control devices - Google Patents

Abstract

FIELD: tool-making industry, namely, optical devices and thermal control devices, used in metallurgy.

SUBSTANCE: device for combined acoustic-aerodynamic protection of objectives of thermal control devices allows when using one source of energy - compressed gas - to provide both acoustic effect on pre-lens space with coagulation of small particles of aerosol, and aerodynamic effect with evacuation of these particles beyond the limits of this space. Adjustment of acoustic gas emitter is performed both by intensiveness of sound energy and frequency of acoustic oscillations for more efficient coagulation of particles of aerosols with varying concentrations and dimensions. Usage of invented device provides efficient protection of lenses of heat control devices from effect of aerosol particles, decreased operation costs and increases reliability and precision of thermo-technical measurements.

EFFECT: increased reliability and precision of thermo-technical measurements.

3 cl, 1 dwg

Description

The invention relates to the field of instrumentation, namely to optical devices and heat control devices used in metallurgy.

In known designs of tuyere devices, protective housings used to install radiation pyrometers, photopyrometers, spectral ratio pyrometers and other types of instruments that measure temperature and heat fluxes, in order to prevent the ingress of dust, smoke and soot, emitting and absorbing gases from the measurement object (thermal engineering object) blowing is done on the lens of the sensitive elements of the device in front of the lens, using, for example, compressed air. Compressed air or inert gas is fed into the internal cavity of the sighting fixture to create resistance to the penetration of flue gases, combustion products to the optical system of devices. This applies, first of all, to dusty technological volumes such as open-hearth furnaces (vaults and regenerators), converters, copper smelting furnaces, mixers, heating furnaces, glass melting furnaces, etc. [1-3].

However, the disadvantage of these devices is the relatively high consumption of compressed air or inert gas, which in this case has high requirements for cleaning themselves from oil, dust, moisture. In addition, at the same time, it is not possible to eliminate the ingress of sensitive elements of fine dust on the pyrometer lenses, which, due to the vortex nature of the flows, can diffusely penetrate through the jet curtains and streams. This leads to frequent clogging of the optics of the pyrometers, which distorts the readings of the instruments and requires frequent cleaning.

Also known is the method and design of the device for implementing this method of protecting the lenses of sensors of devices from industrial dust, soot, smoke by sound coagulation with a frequency of 0.5-20 kHz [6].

This method and device design have the following disadvantages: high energy costs and complex device design, since the entire working space of the unit in which measurements are taken is exposed to the acoustic field. For example, in order to measure the temperature of an open-hearth furnace, the upper and lower space of the furnace must be subjected to acoustic influence. This requires a large amount of energy resources. If you want to constantly monitor the temperature of the workpiece of the rolling mill, then the energy costs for creating an acoustic field will be even greater. The strict requirement to the noise level (not more than 75 dB in production rooms) that arises when implementing the method of sound coagulation in an open room makes this method unacceptable, since there is a question about protecting the health of the personnel serving these objects.

Also known is the method and design of the device, eliminating the influence of smoke and vapors on the temperature measurement results by a radiation pyrometer, in which it is proposed to use the known coagulating action of ultrasound [8]. In this method and the design of the device that implements this method, the main factors that determine the degree and speed of gas purification by ultrasonic coagulation are determined: the intensity and frequency of sound, exposure time, initial concentration and particle size of the aerosol.

However, a disadvantage of the known methods and device designs [7, 8] is the orientation on the use of ultrasonic emitters. So in the method [8] it is indicated the use of a ring-type ultrasonic emitter located coaxially with the optical axis of the pyrometer lens. In ultrasonic emitters, piezoelectric elements are used that convert electrical vibrations into ultrasonic ones. In this case, it becomes difficult to control (change) the frequency and intensity of ultrasound of such an emitter [7] for tuning to the initial concentration and particle size of the aerosol [8]. In addition, it is known that large particles (with a diameter of 500 or more micrometers) are not affected by sound vibrations in the frequency range of 0.5–20 kHz [6].

The disadvantages of the known devices are: the use of ultrasonic oscillation emitters based on the use of piezoelectric elements requiring an additional supply of electricity, which complicates and increases the cost of the design of devices; in addition, during measurements it is difficult, when using ultrasonic emitters, to change the intensity and frequency of sound vibrations to adjust the concentration and size of the aerosol particles. In this case, relatively large particles are not subject to the coagulation effect of ultrasonic vibrations and stick to the surface of the lenses.

The problem solved by the present invention is a more complete protection of the lenses of the lenses of optical thermal control devices, and consequently, increased measurement accuracy from suspended particles, soot and smoke deposited on the lenses, as well as cheaper design of the device.

The problem is solved through the use of a single energy source - compressed gas for the simultaneous (combined) use of gas blowing particles (for protection against large particles) and the creation of a sound field with an adjustable range of intensity and frequency of sound vibrations (for protection against small particles), with the possibility tuning sound vibrations to the concentration and particle size for their effective coagulation [6].

The drawing shows a diagram of a device for combined protection of the lenses of heat control devices.

The device contains:

1 - instrument housing;

2 - sensitive element;

3 - a lens;

4 - sighting lance;

5 - pipeline;

6 - nozzle;

7 - resonator tube;

8 - end screw plug;

9 - stock;

10 - flywheel;

11 - crane.

The nozzle 6 is installed coaxially to the tube of the resonator of sound vibrations 7 and is located on the inner cavity of the sighting lance 4. The length of the resonator is regulated using a screw plug 8, rod 9 and flywheel 10. The flow of protective gas is regulated by a valve 11.

The inventive device operates as follows: through a pipe 5 through a nozzle 6, a jet of protective gas (purified air, nitrogen or other inert gases) with a pressure of 0.5-2 at (0.05-0.2 MPa) is supplied to the working space of the sighting lance 4 . In this case, the maximum gas flow rate (G _g ) is determined with a fully open valve 11 with the area of the outlet cross section of the nozzle 6 according to the formula [9, p.119]:

where K _g is a coefficient depending on the nature of the gas;

P _t - gas pressure;

T _t - gas temperature;

W _cr - the area of the outlet section of the gas nozzle.

When a gas stream enters the resonator 7, sound vibrations occur in it, their frequency (f) depends on the length of the resonator H _p and is determined by the formula [4]:

f = b _o H _p ^-m ,

where b _o = 43300-43400,

N _p - the length of the resonator, mm,

m = 0.8-0.9.

The gas flow rate (G _g ) through the nozzle 6 is associated with the sound intensity (I _s ) through a coefficient (K _s ) determined by the energy efficiency of sound vibrations [4]:

I _s = K _s G _g .

In the proposed device, the gas flow rate and, consequently, the intensity of sound vibrations is regulated by a valve 11; the frequency of sound vibrations is regulated by moving the screw plug 8 using the rod 9 and the flywheel 10. Sound gas through the internal cavity of the sighting lance 4 enters the working space of a controlled volume.

Thus, this device simultaneously creates conditions for acoustic-aerodynamic protection against fine dust (up to 500 microns) - acoustic protection, and coarse dust (over 500 microns) - aerodynamic protection. Fine dust coagulates due to the influence of sound vibrations. The removal of large particles from the optics and the aerodynamic shutter from penetration of large particles into the casing from the outside is ensured by the flow of gas leaving the casing after scoring. To adjust the sound vibrations to a specific frequency, depending on the size of the particles, a change in the length of the resonator (H _p ) is used. To adjust the sound intensity depending on the concentration of particles, a change in gas flow rate (G _G ) is used. Moreover, to protect optics from both large and small particles, the same energy source is used - the supplied compressed gas.

Pilot samples were manufactured at Seversky Tube Works OJSC to protect the lenses of radiation pyrometers on open-hearth and heating furnaces from dust. As a result of the tests, the following device parameters were identified:

Gas pressure 0.5-2 at (0.05-0.2 MPa);

nozzle diameter 6 = 14-3 mm;

the diameter of the resonator 7 = 20-25 mm;

distance from the nozzle exit section to the cavity entrance (Lc) = 60-80 mm;

the cavity length varies between 35-100 mm;

diameter of the sighting lance (DK) = 100-133 mm;

length of sighting lance (Lк) = 1400-1600 mm;

the distance from the axis of the nozzle-resonator to the lens (Ll) = 50-120 mm

The manufacture of prototypes of devices and experimental studies related to the operation of these devices have revealed the simplicity of manufacturing the device, low gas consumption. If earlier the cleaning of the pyrometer lenses installed on open-hearth furnaces with a very high degree of dustiness with simple air blowing was required several times a day, then when using the proposed device, this need generally disappeared. Reduced operating costs for the maintenance of devices. Cases of failure of the measuring equipment due to significant clogging of the lenses were excluded. The reliability and accuracy of measuring the temperature of the object has increased. Compressor air consumption decreased, the service life of the sighting lance increased.

Using the invention will maximize the protection of the lenses of devices that measure the temperature of thermal units.

Information sources

1. Toperver N.I., Sherman M.Ya. Thermotechnical measuring and regulating devices at metallurgical plants. M.: Metallurgizdat, 1956, 606 p.

2. Tuluevsky Yu.N., Nechaev E.A. Information problems of intensification of steelmaking processes. M .: Metallurgy, 1978, 192 p. (102-103 p.).

3. Kotov K.I., Shershever M.A. Means of measurement, control and automation of technological processes of computing and microprocessor technology. M .: Metallurgy, 1989, 496 (124-125 p.).

4. Voronov G.V. Intensification of heat and mass transfer processes in metallurgical furnaces and thermal units due to the energy of the acoustic field. Abstract of dissertation for the degree of Doctor of Technical Sciences. Yekaterinburg, 1996 USTU-UPI.

5. Radiation pyrometer "RAPIR" assembly and operating instructions, Kaluga, 1964, 47 p.

6. Ultrasound. - Small Encyclopedia. M .: Soviet Encyclopedia, 1979, 161-162 p.

7. Copyright certificate of the USSR, No. 100943 of 01/01/1955.

8. TERA telescope - 50 radiation pyrometers. Installation and operating instructions, Kamenetz-Podolsk, 1969.

9. Telegin A.S. Thermotechnical calculations of metallurgical furnaces. M .: Metallurgy, 1970, 528 p.

Claims (3)

1. A device for combined acoustic-aerodynamic protection of the lens of a thermal control device with a sensitive element and a lens, including a cylindrical sighting lance, a nozzle for supplying a protective gas to the sighting lance for blowing off combustion products of flue gases, dust particles, a nozzle for supplying a protective gas and resonator located coaxially on the perpendicular axis of the sighting lance. 2. The device according to claim 1, characterized in that the pipe for supplying a protective gas contains a control valve. 3. The device according to claim 1, characterized in that the resonator contains an end plug with a thread, made with the possibility of movement along the length of the resonator to change its length.