Acoustic gas analyzer

Description

[0001] The utility model relates to acoustic gas analyzers designed to determine the concentration of industrial gas components, which can be used in the oil and gas, coal and other industries.

[0002] An acoustic gas analyzer is known from the prior art (patent RU 57467 for utility model, published 10.10.2006).

[0003] The acoustic gas analyzer comprises a measuring chamber made in the form of a resonator, which is a hollow cylinder with openings for the passage of the analyzed gas, made in the middle part along the length of the resonator, a sound source and receiver installed at opposite ends of the resonator, and a measuring circuit, wherein a frequency-controlled signal generating unit connected to the sound source, a resonant frequency extraction unit including a digital filter and connected to the sound receiver, and a microprocessor unit for processing signals and controlling the operation of the gas analyzer are introduced into the measuring circuit, wherein one of the control outputs of the microprocessor unit is connected to the input of the frequency-modulated signal generating unit, the second control output of the microprocessor unit is connected to the digital filter of the resonant frequency extraction unit, and the output of the resonant frequency extraction unit is connected to the input of the microprocessor unit.The sensitive element of this gas analyzer is an acoustic resonator equipped with a microphone, telephone, temperature and humidity sensor.

[0004] The gas analyzer is characterized by high stability of readings, absence of sensitivity drift during prolonged exposure to high concentrations of monitored gases and vapors, including high-boiling hydrocarbons.

[0005] The main disadvantage of the known gas analyzer is the relatively long time it takes to measure vapors that have a high density relative to air, which is associated with the low rate of entry of controlled substances into the gas analyzer resonator.

[0006] The total area of ​​the holes in the resonator is a compromise between the gas analyzer's response speed and its stability. Increasing the diameter and number of holes with increasing air flow leads to a decrease in the resonator's Q factor and an increase in noise. Reducing the diameter and number of holes in the resonator significantly increases the gas analyzer's stability but degrades its time-dependent characteristics.

[0007] The solution to the problem is to force the air to be analyzed into the resonator area of ​​the gas analyzer or directly into the resonator.

[0008] The following methods for solving the above problem are known from the prior art: external or internally installed pumps of gas analyzers, supply of analyzed air through air ejectors fed by external compressed air.

[0009] Such solutions have a number of fundamental drawbacks, including the limited service life and operating temperature range of the pumps, explosion safety requirements, and the possibility of parasitic resonances forming in the resonator due to the sound harmonics of the air pressure caused by the pumps. The use of ejectors is limited by the availability of compressed air in the instrumentation.

[0010] To eliminate the above mentioned disadvantages and significantly reduce the measurement time, the gas analyzer is equipped with a fan (RU patents No. 127928, 2762858, 191610, 200344, USSR copyright certificate No. 340946).

[0011] The closest to the declared gas analyzer is an infrared gas analyzer consisting of a cylindrical body, on the surface of which a connector for connecting external circuits is installed, and inside which there is an infrared optical sensor, including openings for the input and output of the analyzed gas, an infrared LED, interference filters and a gas cuvette located along the infrared radiation of the LED with focusing lenses of infrared radiation, infrared photodetectors and an electronic control unit, including a communication board to which a control microcontroller, an interface signal generator are connected, while the gas analyzer includes a gas channel consisting of coaxial internal and external cylindrical pipes, and the outer pipe is hermetically connected to the cylindrical body, and a dust filter is located at its output,and the inner tube is coaxially and hermetically connected to an infrared optical sensor, inside which a porous metal filler, an aerosol filter, a flow stimulator of the analyzed gas, and an internal temperature meter are coaxially and sequentially arranged. An external gas temperature meter and a protective mesh are located at its end. A cylindrical electric furnace is installed outside it, and an additional control board is installed inside the cylindrical body (RU Patent No. 191610 for Utility Model, published on August 14, 2019). In the known gas analyzer, to reduce the measurement time, the analyzed air is supplied to the infrared detector by a fan.

[0012] In order to ensure the operability of the optical sensor at low temperatures, a heater in the form of a cylindrical electric furnace is used to heat the air to a temperature of 5-25°C and simultaneously heat the fan.

[0013] This solution results in increased energy consumption and is excessive for the purpose of increasing convective gas diffusion into the resonator. Since some fuel vapors have a flash point below 135°C (temperature class T4), using a ring electric furnace is potentially hazardous even with special explosion protection measures. Furthermore, oxidation of the monitored gas vapors on the heated surface of the electric furnace can lead to a decrease in measured concentrations.

[0014] To eliminate these shortcomings and significantly reduce the measurement time of the acoustic resonance gas analyzer, including at low temperatures, it is proposed to equip the gas analyzer with a built-in fan that heats only the electric motor area. The need for motor heating is necessitated by the fact that the minimum operating temperature for most fans is -20°C.

[0015] The objective of the claimed utility model is to create an acoustic gas analyzer that has high stability and reliability of operation in various temperature ranges.

[0016] The technical result of the claimed utility model consists in increasing the safety of the acoustic gas analyzer at low temperatures due to the presence of a flat electric heater in the fan electric motor zone and a protective casing without significantly increasing energy consumption.

[0017] The technical result is achieved in that the acoustic gas analyzer includes the following, located in a single housing: an acoustic resonator with a microphone, a telephone, and a temperature and humidity sensor installed thereon; a fan; a heater; an electronic unit based on a microcontroller, characterized in that the acoustic resonator is placed in a casing with end and side ventilation openings protected by a filter, the fan is placed inside the casing in front of the acoustic resonator, a temperature sensor is located on the fan housing in the area of ​​the fan motor, a flat electric heater installed in the area of ​​the fan motor is used as a heater, the electronic unit based on the microcontroller is connected to the fan temperature sensor, the fan, the fan heater, the microphone, the temperature and humidity sensor, the telephone, and the acoustic resonator.

[0018] The features and essence of the claimed utility model are explained in the following detailed description, illustrated by drawings (Figs. 1 and 2).

[0019] Fig. 1 shows a diagram of the claimed acoustic gas analyzer.

[0020] Fig. 2 shows a structural diagram of an acoustic gas analyzer with components included in the electronic unit.

[0021] In Fig. 1 and 2, the following is indicated by positions:

[0022] 1 - acoustic resonator;

[0023] 2 - microphone;

[0024] 3 - telephone;

[0025] 4 - temperature and humidity sensor;

[0026] 5 - casing;

[0027] 6 - end vents;

[0028] 7 - side ventilation holes;

[0029] 8 - filter;

[0030] 9 - fan;

[0031] 10 - heater;

[0032] 11 - temperature sensor;

[0033] 12 - electronic unit;

[0034] 13 - body;

[0035] 14 - adapter;

[0036] 15 - microcontroller;

[0037] 16 - microphone amplifier;

[0038] 17 - power amplifier;

[0039] 18 - digital resistor (potentiometer);

[0040] 19 - Digital Signal Generator (DDS);

[0041] 20 - indicator;

[0042] 21 - RS-485 interface driver;

[0043] 22 - 4-20 tA interface driver;

[0044] 23 - resonator holes.

[0045] Acoustic resonator 1 (Fig. 1 and 2) with microphone 2, telephone 3 and temperature and humidity sensor 4 mounted thereon is installed in casing 5 having ventilation end 6 and side 7 openings protected by filter 8. Inside casing 5, in front of resonator 1, fan 9 is installed, in which, in the engine area, flat electric heater 10 and temperature sensor 11 are installed. Casing 5 can be made either dust- and moisture-proof or explosion-proof.

[0046] The wires connecting the microphone 2, telephone 3, temperature and humidity sensor 4, fan 9, temperature sensor 11, fan heater 10, resonator 1 are connected to the electronic unit 12 of the gas analyzer through a sealed adapter 14.

[0047] The air being analyzed enters the casing 5 through the end ventilation openings 6 of the casing 5, blows over the resonator 1, enters the resonator 1 through the openings 23 on the body of the resonator 1 and exits through the side ventilation openings 7 of the casing 5.

[0048] Ventilation openings 6 and 7 are protected by a filter 8, for example, made of porous fluoroplastic, porous metal ceramics or other material that allows air to pass through, does not react with the substances being analyzed and has hydrophobic properties.

[0049] The central element of the electronic unit 12 of the acoustic gas analyzer (Fig. 2) is the microcontroller 15. The microcontroller 15 is connected via a digital communication channel to the telephone control unit (TCU), which consists of a digitally controlled signal generator (DDS) 19 and a power amplifier 17, which is controlled by a digital resistor 18. The codes of the frequency and level of the sound signal, which is generated by the telephone 3, installed in the resonator 1, are transmitted to the digital inputs of the TCU. To control the sound level when determining the resonant frequency in the resonator 1, a microphone 2 is used, connected via a microphone amplifier 16 with detection of the signal amplitude to the analog input of the microcontroller 15. Based on the readings of the temperature and humidity sensor 4, the microcontroller 15 makes a correction for temperature and humidity.

[0050] Heater 10, using control signals from microcontroller 15, provides heating of the motor zone of fan 9. The heating temperature is controlled by temperature sensor 11, installed on the housing of fan 9 in the motor zone.

[0051] The resonator has a number of holes 23, which provide gas exchange between the internal cavity of the resonator and the external analyzed medium.

[0052] Electronic unit 12 operates in multitasking mode. The first task is scanning the resonant characteristic of the resonator and calculating the resonance frequency. The second task is maintaining the maximum resonance curve by adjusting the frequency of the signal generated by microcontroller 15. The third task is polling and processing data from temperature and humidity sensor 4 of resonator 1 and temperature sensor 11 of fan 9. The fourth task is calculating the gas concentration using calibration coefficients and compensation coefficients for humidity and temperature pre-stored in the memory of microcontroller 15, taking into account readings from the temperature and humidity sensor of the resonator, the temperature sensor of the fan, and the resonant frequency.The fifth task is generating external signals: generating a 4-20 mA current output on a linear scale of measured concentrations, processing ModBus protocol requests from external controllers, indicating gas concentration on display 20, setting / resetting output discrete signals based on the set values ​​of emergency vapor concentration. The sixth task is controlling the operation of fan 9 and heater 10 of fan 9 based on data received from temperature and humidity sensor 4 of resonator 1 and temperature sensor 11 of fan 9. The seventh task is outputting information on gas concentration to external devices via analog (4-20 mA) and digital (RS-485) outputs.

[0053] All information about the gas analyzer settings is entered in advance into the non-volatile EEPROM memory of the microcontroller 15 of the electronic unit 12.

[0054] The operating algorithm of the acoustic gas analyzer is as follows.

[0055] When the power is turned on, the microcontroller 15 determines the temperature and humidity of the surrounding air based on the information from the temperature sensor 11 of the fan 9 and the temperature and humidity sensor 4 installed in the resonator 1.

[0056] If the temperature is higher than the minimum operating temperature of the fan, then, according to the control signals of microcontroller 15, fan 9, microphone 2, telephone 3 are sequentially switched on and the gas analyzer enters the operating mode.

[0057] If the air temperature is below the minimum operating temperature of the fan, the microcontroller 15 issues control signals to turn on the heater 10 to heat the fan motor 9.

[0058] During the operation of the gas analyzer, the microcontroller 15 continuously monitors the temperature of the fan motor 9 based on the information from the temperature sensor 11 of the fan 9 and the air temperature in the area of ​​the resonator 1 based on the information from the temperature and humidity sensor 4 on the resonator 1 and, by adjusting the power of the heater 10, maintains its value at the level of the operating (permissible) temperature.

[0059] The result of the gas concentration measured by the microcontroller 15 can be transmitted via the RS-485 interface or via the 4-20 mA current loop to external devices via the drivers 21, 22 of the RS-485 or 4-20 mA interfaces connected to the microprocessor 15, and analog (4-20 mA) or digital (RS-485) outputs.

[0060] The conducted analysis of the state of the art allowed us to establish that there are no analogues with a set of essential features identical to the essential features of the claimed gas analyzer, which indicates that the claimed gas analyzer complies with the patentability condition of “novelty”.

Claims

1. An acoustic gas analyzer comprising the following, all located in a single housing: an acoustic resonator with a microphone, a telephone, and a temperature and humidity sensor mounted thereon, a fan, a heater, and an electronic unit based on a microcontroller, characterized in that the acoustic resonator is placed in a casing with end and side ventilation openings protected by a filter, the fan is placed inside the casing in front of the acoustic resonator, a temperature sensor is located on the fan housing in the area of ​​the fan motor, a flat electric heater mounted in the area of ​​the fan motor is used as a heater, the electronic unit based on the microcontroller is connected to the fan temperature sensor, the fan, the fan heater, the microphone, the temperature and humidity sensor, the telephone, and the acoustic resonator.

2. An acoustic gas analyzer according to paragraph 1, characterized in that the filter is made of a porous material that has hydrophobic properties, allows air to pass through and does not react with the substances being analyzed, for example, porous fluoroplastic or porous metal ceramics.

3. An acoustic gas analyzer according to paragraph 1, characterized in that the casing is made explosion-proof or dust- and moisture-proof.

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