CN104089918A - Oil gas online detection device based on non-dispersed infrared method - Google Patents

Abstract

The invention discloses an oil and gas online detection device based on a non-spectral infrared method, which comprises: an active pumping unit, an oil and gas concentration detection unit, an oxygen and temperature and humidity measurement unit, an analysis host and a workstation. The invention is based on infrared spectroscopy, which improves the accuracy of oil and gas concentration detection; the infrared analysis room, with a diameter of 25mm, effectively increases the service life and sensitivity of the device, adopts mechanical stainless steel pipeline suction at 8 points from the oil and gas dangerous source site, and The explosion-proof analysis instrument is installed outside the oil depot, which reduces the risk of oil and gas explosion. At the same time, 8 gas sampling and pre-extraction circuits are used to detect the oil and gas concentration at each point online in real time; the high-frequency solenoid valve and the developed combined control valve body are used to ensure Accurately supply and analyze the gas source for each gas path, determine the position signal, start without error, and have no blockage; set up oxygen, temperature and humidity sensors to improve the reliability of the alarm; use the CAN bus to realize the long-distance transmission of the alarm signal, Improved reliability.

Description

An oil and gas online detection device based on non-spectral infrared method

technical field

The invention belongs to the technical field of oil and gas detection, and in particular relates to an on-line oil and gas detection device based on a non-spectral infrared method. the

Background technique

At present, on-line monitoring of flammable and explosive gases and sensor calibration technology have become the key links and technical foundations of safety monitoring and environmental early warning, and at the same time provide data support and theoretical criteria for safety assessment. The Petroleum and Natural Gas Industry Standard Sy6503-2008 of the People's Republic of China stipulates that a flammable gas detection and alarm system should be installed in places where there are flammable gas release sources. the

Oil-gas mixture explosion is a typical gas explosion, and gas explosion is one of the main forms of explosion disasters in industrial production and living fields. Most of the petroleum products stored in the oil depot are volatile. When the concentration of the mixture of oil, gas and air is within the explosion range, an explosion will occur immediately if the detonation energy is encountered. The concentration of the mixture of oil, gas and air is higher or lower than the upper and lower limits of the explosion range. There will be no explosion for a limited time. the

At present, online monitoring of flammable and explosive gases has become a key link and technical basis for safety monitoring and environmental early warning, and at the same time provides data support and theoretical criteria for safety assessment. Traditional gas online monitoring technologies mainly include gas chromatography, gas sensor method, Fourier transform infrared spectroscopy, photoacoustic spectroscopy, etc., but in actual use, these methods have complex sampling, cross-sensitivity, poor long-term stability, detection Disadvantages such as insufficient gas components and high cost. the

The catalytic combustion detection method used more at this stage has the following disadvantages:

Sensor monitoring range: Catalytic combustion sensors have a fixed exposure capability range within which the monitoring performance is reliable. The use of exceeding the monitoring range and overloading of the sensor load affect its accuracy, and the sensor is often in a saturated state accordingly; the gas concentration is lower than the conventional range, which will weaken the reflected signal, coupled with environmental noise interference, making the instrument reading inaccurate , thereby reducing the accuracy and resolution of the instrument. the

Cross-effect of the gas to be measured: The catalytic combustion sensor determines the concentration of the gas by means of a catalyst at a low temperature (200-400°C) to achieve complete oxidation of organic matter. This reaction process is common to many gases. The cross influence of the gas to be tested makes the test result unable to reflect the actual content of the test gas, and the test result loses its scientific value and rationality. the

The life problem of the sensor: the catalyst failure of catalytic combustion and the poisoning of the catalyst are the fatal disadvantages of the sensor. Catalytic combustion sensors all have life factors. The longest life is 2 years in the air. Basically, the sensitivity will continue to decline after 6 months. It needs repeated debugging to maintain use. the

As a fast and accurate gas analysis technology, NDIR (non-spectral) infrared gas analyzer is very common in continuous pollutant monitoring system and motor vehicle exhaust detection application. The main working principle is to realize the detection of oil and gas concentration by utilizing the selective absorption of infrared radiation by gas and its absorption intensity as a function of gas concentration. The system converts the intensity of infrared radiation into a voltage signal, and analyzes the voltage signal through a digital processor to achieve accurate measurement of oil and gas concentration. the

However, the current non-spectral infrared gas analyzer has the following defects when measuring oil and gas in oil depots: First, it does not consider the multi-component composition of oil and gas and the characteristics of easy adsorption, and the designed oil and gas concentration sensor has structural defects, resulting in certain errors in the measurement of oil and gas concentration; The second is that the influence of temperature, humidity and oxygen concentration on the explosion limit of oil and gas is not considered, and the alarm criterion is not accurate enough; the third is that the oil and gas sampling process when oil and gas are simultaneously measured at multiple points in a confined space is not considered. the

Contents of the invention

The purpose of the embodiments of the present invention is to provide an oil and gas online detection device based on the non-spectral infrared method, which aims to solve the existing errors in the oil and gas concentration measurement of the current non-spectral infrared gas analyzer when measuring the oil and gas in the oil depot; it does not consider temperature, humidity and The influence of oxygen concentration on the explosion limit of oil and gas is not accurate enough in the alarm criterion; the problem of oil and gas sampling process in the simultaneous measurement of oil and gas at multiple points in a confined space is not considered. the

The embodiment of the present invention is achieved in this way, an oil and gas online detection device based on the non-spectral infrared method, the oil and gas online detection device based on the non-spectral infrared method includes: an active pumping unit, an oil and gas concentration detection unit, oxygen and temperature and humidity Measuring unit, analysis host, CAN bus, workstation;

The active pumping unit is used to collect the mixed gas through 8 sampling points set in the oil storage;

The oil and gas concentration detection unit, oxygen and temperature and humidity measurement unit are connected with the active pumping unit to measure the oxygen concentration, temperature and humidity of the mixed gas collected by the active pumping unit;

The analysis host is connected with the oil and gas concentration detection unit, oxygen and temperature and humidity measurement unit, and is used to analyze and display the mixed gas oil and gas concentration, oxygen concentration, temperature and humidity measured by the oil and gas concentration, oxygen, temperature and humidity measurement unit;

The workstation is connected to the analysis host through the CAN bus, and receives the mixed gas oil and gas concentration, oxygen concentration, temperature and humidity analyzed by the analysis host. If the gas concentration exceeds the upper limit of the explosion, an alarm will be issued to realize the hierarchical early warning monitoring and alarm of oil and gas hazard sources. the

Further, the active air extraction unit adopts on-site 8-point mechanical stainless steel pipeline suction. the

Further, the on-site 8-point mechanical stainless steel pipeline suction adopts a high-frequency solenoid valve and a developed combined control valve body. the

Furthermore, the oil and gas concentration detection unit is composed of an infrared gas absorption chamber, an infrared light source, an infrared detector and an amplification circuit; the specific working principle is: the light source component modulates continuous infrared radiation into intermittent radiation at 6.25 Hz, and then alternately passes through the gas chamber The analysis side and the reference side (single tube is separated by a half-air chamber, and the reference side is sealed with high-purity nitrogen that does not absorb infrared rays), and finally the detector (the detector used in this instrument is a lithium cholate pyroelectric detector) absorb. When the analysis room is fed with high-purity nitrogen gas, the infrared radiation energy received alternately by the detector is equal to that of the reference side and the analysis side, and the output signal of the instrument is zero; The specific signal remains unchanged, while the analytical signal changes due to the absorption of the analyte gas in the analysis chamber, thus producing an output signal proportional to the concentration of the analyte gas. The tiny electrical signal becomes a direct current signal proportional to the concentration of the gas to be measured through multiple links such as pre-amplification, main amplification, frequency selection, phase-sensitive detection, and filtering. the

Further, the diameter of the infrared analysis chamber is 25mm. the

Furthermore, the infrared analysis chamber adopts a one-time molding process, and the inner wall of the gas chamber adopts a 1mm thick overall gold-plated layer, and the sealing materials at both ends of the gas chamber are bonded with high-transparency gemstone lenses. the

Furthermore, the installation height of the air extraction unit is within 1m, and the corners of the oil storage and the places where the size and structure change are the key installation points. the

Further, the analysis host is composed of single-chip microcomputer control, TFT color liquid crystal display, A/D conversion circuit, and digital interface circuit. the

The oil and gas on-line detection device based on the non-spectral infrared method provided by the present invention is firstly based on the infrared spectroscopy method to measure the content of each component in common oil and gas mixtures by obtaining the intensity of the characteristic absorption peak; it is obtained that the oil and gas have a strong, single The absorption peak, and the design of the oil and gas concentration detection unit based on this, improves the detection accuracy; the designed infrared analysis room has a diameter of 25mm, which is 3-6 times that of the conventional infrared analysis room, and the anti-pollution ability is increased by 3-6 times , which effectively increases the long life and sensitivity in the measurement process. As for the loss of the infrared optical path, the entire infrared analysis chamber adopts a one-time molding process, and a 1mm thick overall gold-plated layer is used on the inner wall of the gas chamber. The sealing material at both ends is bonded with high-transparency sapphire lens, so that the infrared light emitted by the infrared light source passes through the optical gas chamber in a form of close to zero loss, which accurately ensures the analysis ability of the analyzer; adopts 8 points from the oil and gas hazard source site The mechanical stainless steel pipeline sucks air, and the explosion-proof analysis instrument is installed outside the oil depot, which reduces the risk of oil and gas explosion. At the same time, 8 gas sampling and pre-extraction circuits are used to detect the oil and gas concentration at each point online in real time; high-frequency solenoid valves and R&D The combined control valve body ensures the accurate supply and analysis of each gas source, position signal judgment, error-free start-up, and no blockage; oxygen, temperature and humidity sensors are set; CAN bus is used to realize long-distance transmission of alarm signals , improving reliability. The structure of the present invention is simple, and it better solves the oil gas concentration measurement error existing in the current non-spectral infrared gas analyzer when measuring the oil gas in the oil depot; it does not consider the influence of temperature, humidity and oxygen concentration on the explosion limit of oil gas, and the alarm criterion It is not accurate enough; it does not consider the problem of oil and gas sampling process when oil and gas are measured at multiple points at the same time in a confined space. the

Description of drawings

Fig. 1 is a schematic structural diagram of an oil and gas online detection device based on a non-spectral infrared method provided by an embodiment of the present invention;

Fig. 2 is the schematic diagram of 8 sampling points of the oil storage house that the embodiment of the present invention provides;

Fig. 3 is the structural representation of analysis host computer and workstation that the embodiment of the present invention provides;

In the figure: 1. Oxygen and temperature and humidity measurement unit; 2. Active pumping unit; 3. Analysis host; 4. Workstation; 5. Oil and gas concentration detection unit. the

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. the

The application principle of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. the

As shown in Figure 1, the oil and gas online detection device based on the non-spectral infrared method in the embodiment of the present invention mainly consists of an oxygen and temperature and humidity measurement unit 1, an active air pumping unit 2, an analysis host 3, a workstation 4, and an oil and gas concentration detection unit 5 composition;

The active pumping unit 2 is used to collect the mixed gas through 8 sampling points set in the oil storage;

The oil and gas concentration detection unit 5, the oxygen and temperature and humidity measurement unit 1 are connected to the active pumping unit 2, and are used to measure the oil and gas concentration detection unit, oxygen concentration, temperature and humidity of the mixed gas collected by the active pumping unit 2;

The analysis host 3 is connected with the oil gas concentration detection unit 5, the oxygen and temperature and humidity measurement unit 1, and is used to analyze the oil gas concentration, oxygen concentration, temperature and humidity of the mixed gas measured by the oil gas concentration, oxygen, temperature and humidity measurement unit 1, and to display;

The workstation 4 is connected to the analysis host 3 through the CAN bus, and receives the mixed gas oil and gas concentration, oxygen concentration, temperature and humidity analyzed by the analysis host 3. If the gas concentration exceeds the upper limit of the explosion, an alarm will be issued to realize the hierarchical early warning monitoring of oil and gas hazard sources and alarm;

In the embodiment of the present invention, the active air extraction unit adopts on-site 8-point mechanical stainless steel pipeline suction; the on-site 8-point mechanical stainless steel pipeline suction adopts high-frequency electromagnetic valve and R&D combined control valve body, and the oil and gas concentration The detection unit is composed of an infrared gas absorption chamber, an infrared light source, an infrared detector and an amplifying circuit. The specific working principle is: the light source component modulates the continuous infrared radiation into intermittent radiation of 6.25Hz, and then alternately passes through the analysis side and the reference side of the gas chamber (single tube is separated by a half gas chamber, and the reference side is sealed without absorbing infrared rays. high-purity nitrogen), and finally absorbed by the detector (the detector used in this instrument is a lithium cholate pyroelectric detector). When the analysis chamber is fed with high-purity nitrogen gas, the infrared radiation energy received alternately by the detector is equal to that of the reference side and the analysis side, and the output signal of the instrument is zero; The specific signal remains unchanged, while the analytical signal changes due to the absorption of the analyte gas in the analysis chamber, thus producing an output signal proportional to the concentration of the analyte gas. The tiny electrical signal becomes a direct current signal proportional to the concentration of the gas to be measured through multiple links such as pre-amplification, main amplification, frequency selection, phase-sensitive detection and filtering;

The diameter of the infrared analysis chamber is 25mm; the infrared analysis chamber adopts a one-time molding process, and the inner wall of the gas chamber is made of a 1mm thick overall gold-plated layer, and the sealing material at both ends of the gas chamber is bonded with a high-transparency gemstone lens; the installation of the air extraction unit The height is within 1m, and the corners, dimensions, and structural changes of the oil storage are key installation points; the analysis host is composed of single-chip microcomputer control, TFT color liquid crystal display, A/D conversion circuit, and digital interface circuit. The analysis host 3 is controlled by a single-chip microcomputer, a TFT color liquid crystal display (150×100 VGA), an A/D conversion circuit, and a digital interface circuit. the

The working principle of the present invention is further described in conjunction with Fig. 1-Fig. 3:

In the present invention, in the limited space of the oil depot, the monitored mixed gas is sent to the oil gas concentration detection unit, oxygen and temperature and humidity measurement unit by the active pumping unit, and the concentration test and analysis are completed by the online monitoring non-spectral infrared analysis host, and then passed The CAN bus is transmitted to the workstation in the control room. If the gas concentration exceeds the upper limit of the explosion, an alarm will be issued, which is different from the general combustible gas detection instrument; the device of the present invention considers that the explosion concentration of oil and gas is related to temperature, humidity and oxygen concentration, so the system is coupled at the same time Oxygen, temperature and humidity measurement unit;

The control valves of each measurement point can be opened in turn according to the time period, and the parameters such as oil gas, oxygen, temperature and humidity at different measurement points can be measured one by one, and the field sensor data in the tank can be transmitted to the analysis host for display; The CAN bus directly transmits the data on the analysis host to the background workstation in the control room for analysis and processing by the graded early warning software, realizing the graded early warning monitoring and alarm of oil and gas hazard sources, especially in the design of sampling, adopting on-site 8-point mechanical stainless steel pipeline Inhale, and install the explosion-proof analysis instrument outside the oil depot, thereby greatly reducing the risk of oil and gas analysis, ensuring that there is no circuit system in the tank room, and avoiding ignition caused by measurement;

The analysis host system is composed of single-chip microcomputer control, TFT color liquid crystal display (150×100VGA), A/D conversion circuit, digital interface circuit, and self-developed control software with Chinese menus; the power control system can use AC: 20- 27V; 70-250V (50Hz), DC: 20-36V; 70V-250, output two AC/DC power supply modules for microcomputer system and electromagnetic three-way valve respectively, transformer and +5V output regulated power supply and +5V input , ±12V output DC/DC boost module to supply power for other parts of the measurement system;

The advantages of the present invention are:

1) Based on infrared spectroscopy, the content of each component in common oil and gas mixtures (gasoline, diesel and kerosene, etc.) is determined by obtaining the intensity of the characteristic absorption peak; it is obtained that the oil and gas have a strong and single absorption peak near 3.39 μm, according to this An important feature is the design of the oil and gas concentration detection unit, which improves the detection accuracy;

2) For the long-term measurement state, the adsorption of oil and gas, the humidity of the gas and the tiny dust particles in the gas will all be the key indicators that affect the measurement. However, the largest diameter of the ordinary infrared analysis gas chamber is only 8mm, and the smallest diameter is only 8mm. 4mm, after a long time of measurement, the above factors will be directly attached to the inner wall of the analysis chamber, so that in the small air chamber space, there will be a very high loss of infrared light directly, resulting in a rapid decline in sensitivity. As a result, analytical instruments cannot measure accurately. Aiming at the strong adhesion ability of oil and gas, the designed large-space infrared analysis room has a diameter of 25mm, which is 3-6 times that of conventional infrared analysis rooms. The anti-pollution ability is increased by 3-6 times, and the efficiency is increased. In order to ensure the long-term sensitivity in the measurement process, and for the loss of the infrared optical path, the entire infrared analysis chamber adopts a one-time molding process, and a 1mm thick overall gold-plated layer is used on the inner wall of the gas chamber, and the sealing material at both ends of the gas chamber is measured. Using high-transparency sapphire lens bonding, so that the infrared light emitted by the infrared light source passes through the optical air chamber in a form of close to zero loss, thus accurately ensuring the analysis ability of the analyzer;

3) In terms of sampling design, 8-point mechanical stainless steel pipelines are used to inhale air from the site of oil and gas hazard sources, and the explosion-proof analysis instrument is installed outside the oil depot to reduce the risk of oil and gas explosions. It can detect the oil and gas concentration at each point online in real time; it adopts high-frequency solenoid valve and R&D combined control valve body, uniquely designed combined switching gas circuit, completes fast gas circuit switching in a relatively small volume, and cooperates with the analysis of the analyzer Instructions, timely response to the gas path that needs to be controlled by the instruction, so as to ensure accurate supply of each gas path, analyze the gas source, determine the position signal, start without error, and have no blockage. Therefore, it is preliminarily determined that the installation height is within 1m, and the corners, dimensions, and structural changes are the key installation points;

4) Fully consider the impact of temperature, humidity and oxygen concentration on the explosion limit of oil and gas, and arrange oxygen, temperature and humidity sensors on site. At the same time, when designing the hazard source explosion classification early warning software, the comprehensive criterion method is used to carry out hazard classification early warning. False positives are reduced. the

5) The on-site CAN bus design can transmit the alarm signal reliably and over a long distance, and can be connected with the oil depot monitoring system. the

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range. the

Claims (8)

1. An oil-gas online detection device based on non-spectral infrared method, characterized in that, the oil-gas online detection device based on non-spectral infrared method comprises: active air pumping unit, oil-gas concentration detection unit, oxygen and temperature and humidity measurement unit, Analysis host, CAN bus, workstation; The active pumping unit is used to collect the mixed gas through 8 sampling points set in the oil storage; The oil and gas concentration detection unit, the oxygen and temperature and humidity measurement unit are connected with the active pumping unit, and are used to measure the oxygen concentration, temperature and humidity of the mixed gas collected by the active pumping unit; The analysis host is connected with the oil and gas concentration detection unit, oxygen and temperature and humidity measurement unit, and is used to analyze and display the mixed gas oil and gas concentration, oxygen concentration, temperature and humidity measured by the oil and gas concentration, oxygen, temperature and humidity measurement unit; The workstation is connected to the analysis host through the CAN bus, and receives the mixed gas oil and gas concentration, oxygen concentration, temperature and humidity analyzed by the analysis host. If the gas concentration exceeds the upper limit of the explosion, an alarm will be issued to realize the hierarchical early warning monitoring and alarm of oil and gas hazard sources. 2. The oil and gas online detection device based on the non-spectral infrared method according to claim 1, wherein the active air extraction unit adopts an on-site 8-point mechanical stainless steel pipeline for air suction. 3. The oil and gas online detection device based on the non-spectral infrared method according to claim 2, characterized in that the on-site 8-point mechanical stainless steel pipeline suction adopts a high-frequency electromagnetic valve and a developed combined control valve body. 4. The oil and gas online detection device based on non-spectral infrared method as claimed in claim 1, wherein the oil and gas concentration detection unit is composed of an infrared gas absorption chamber, an infrared light source, an infrared detector and an amplifying circuit. 5. The oil and gas online detection device based on non-spectral infrared method according to claim 4, characterized in that the diameter of the infrared analysis chamber is 25 mm. 6. The oil and gas online detection device based on the non-spectral infrared method as claimed in claim 4, wherein the infrared analysis chamber adopts a one-time molding process, and the inner wall of the gas chamber adopts a 1mm thick integral gold-plated layer, and the two ends of the gas chamber The sealing material is bonded with high-transparency gemstone lenses. 7. The oil and gas online detection device based on non-spectral infrared method according to claim 1, characterized in that the installation height of the air extraction unit is within 1m, and the corners and size and structural changes of the oil storage are installation points. 8. The oil and gas online detection device based on non-spectral infrared method as claimed in claim 1, wherein the analysis host is controlled by a single-chip microcomputer, a TFT color liquid crystal display, an A/D conversion circuit, and a digital interface circuit.