阅读说明：本技术 一种挥发性有机物在线监测系统 (Volatile organic compound on-line monitoring system ) 是由 林炳峰 于 2020-11-16 设计创作，主要内容包括：本发明属于石油化工技术领域,尤其为一种挥发性有机物在线监测系统：包括在线气相色谱仪、烟气采样探头子系统、预处理子系统、供气子系统、数据采集及处理子系统和温压流子系统组成；所述在线气相色谱仪主要包括气路及气路控制模块、柱箱及柱箱控制模块、阀箱及阀箱控制模块、检测器及检测器控制模块、电路模块、工控机模块和色谱模块；在线气相色谱仪采用色谱分离检测技术,检测量程宽、检测灵敏度高,可有效监测烟气排放前非甲烷总烃的浓度变化；测量信号送入数据采集与处理子系统,通过模拟信号传输至DCS系统,同时整套系统结构简单,动态范围广,实时性强,组网灵活,运行成本低,同时系统采用模块化结构,组合方便。(The invention belongs to the technical field of petrochemical industry, and particularly relates to an online volatile organic compound monitoring system which comprises the following components: the system comprises an online gas chromatograph, a smoke sampling probe subsystem, a pretreatment subsystem, a gas supply subsystem, a data acquisition and processing subsystem and a temperature-pressure flow subsystem; the online gas chromatograph mainly comprises a gas path and gas path control module, a column box and column box control module, a valve box and valve box control module, a detector and detector control module, a circuit module, an industrial personal computer module and a chromatographic module; the on-line gas chromatograph adopts a chromatographic separation detection technology, has wide detection range and high detection sensitivity, and can effectively monitor the concentration change of non-methane total hydrocarbons before the emission of flue gas; the measurement signal is sent into the data acquisition and processing subsystem, and is transmitted to the DCS system through the analog signal, and simultaneously the whole set of system has simple structure, wide dynamic range, strong real-time performance, flexible networking and low operation cost, and simultaneously the system adopts a modular structure and is convenient to combine.)

1. The utility model provides an online monitoring system of volatile organic compounds which characterized in that: the system comprises an online gas chromatograph, a smoke sampling probe subsystem, a pretreatment subsystem, a gas supply subsystem, a data acquisition and processing subsystem and a temperature-pressure flow subsystem;

the online gas chromatograph mainly comprises a gas path and gas path control module, a column box and column box control module, a valve box and valve box control module, a detector and detector control module, a circuit module, an industrial personal computer module and a chromatographic module;

the smoke sampling probe adopts a high-precision platinum resistance sensor, a temperature protection element and a back flushing unit, the temperature is controlled to be 200 ℃ at most, and components such as a sampling pipe, a filter element and the like are made of high-temperature resistant materials;

the pretreatment subsystem adopts an integral heating box for heating, all pretreatment components are arranged in the heating box and consist of a secondary filter, a high-temperature air pump, a pneumatic control stop valve, an adjusting needle valve, a flowmeter and other components, and then the heat tracing box is introduced into the analyzer;

the air supply subsystem comprises a zero gas generator and a hydrogen generator, the zero gas generator is an air source purifying treatment device, and the hydrogen generator is a high-sensitivity fuzzy control device and an automatic flow tracking device;

the data acquisition and processing subsystem consists of a central unit, an upper computer (industrial personal computer) and VOC on-line continuous monitoring system monitoring software;

the temperature and pressure flow subsystem is a temperature and pressure flow integrated monitor and a humidity and oxygen transmitter, wherein the temperature and pressure flow integrated monitor is based on the differential pressure measurement principle of the traditional pitot tube, the humidity and oxygen transmitter takes a microprocessor as a core, an ion current and humidity sensor as a measurement unit, and the reference voltage of the two sensors is controlled by a software PID technology.

2. The online volatile organic compound monitoring system according to claim 1, wherein: the on-line gas chromatograph adopts the chromatographic technique to analyze and detect the non-methane total hydrocarbon components and the benzene, the toluene and the xylene, and is used for monitoring the concentration changes of the non-methane total hydrocarbon components and the benzene, the toluene and the xylene in the pipeline.

3. The online volatile organic compound monitoring system according to claim 1, wherein: the smoke sampling probe is a high-temperature heat tracing technology and has the functions of automatic heat tracing temperature control, sampling stop, automatic back flushing and full-flow calibration.

4. The online volatile organic compound monitoring system according to claim 1, wherein: the pretreatment subsystem finishes the multi-stage treatment of the sample gas, so that the analysis instrument can obtain the clean and condensation-free sample gas which meets the requirements, and the long-term reliable operation of the analysis instrument is ensured.

5. The online volatile organic compound monitoring system according to claim 1, wherein: the zero-order generator carries out catalytic cracking on total hydrocarbons in the compressed air to generate zero-order air with less than 0.1PPM (PPM) of hydrocarbons (calculated by methane), the hydrocarbons are converted into carbon dioxide and water vapor in a de-hydrocarbon furnace containing a catalyst, and then the carbon dioxide and the water vapor are filtered and removed again to obtain ideal zero-order air.

6. The online volatile organic compound monitoring system according to claim 1, wherein: the hydrogen generator enables the pressure stability precision range to be better than 0.001 MPa; the electrolytic cell adopts transition metal element catalysis technology, and the hydrogen purity is enabled to reach the oxygen content less than 3PPM and the water content dew point temperature less than minus 40 ℃ through multi-stage purification, the electrolytic cell is used for providing GC-3100 chromatograph carrier gas, FID detector combustion gas and FID detector combustion-supporting gas, a gas supply system continuously provides stable gas supply pressure and flow, and continuous online operation of an analytical instrument can be ensured.

7. The online volatile organic compound monitoring system according to claim 1, wherein: the data acquisition and processing subsystem obtains upper computer software to collect all gas concentration information and working state information, has the functions of generating reports, storing data, inquiring historical records, communicating with environmental protection departments in a network mode and the like, and realizes acquisition of samples with different volumes by configuring sampling quantitative rings with different volumes, thereby realizing online analysis and detection of samples with different concentrations at treatment outlets.

8. The online volatile organic compound monitoring system according to claim 1, wherein: the temperature and pressure flow integrated monitor adopts an S-shaped pitot tube detection head, a pitot tube probe is inserted into a pipeline during measurement, the central axis of the probe is positioned in the center of an overflowing section and is consistent with the direction of a streamline, a full-pressure side hole of the probe is opposite to incoming flow, a static-pressure side hole is opposite to incoming flow, full-pressure static pressure is respectively transmitted to a sensor, and the sensor measures a differential pressure value, namely dynamic pressure.

9. The online volatile organic compound monitoring system according to claim 1, wherein: the sensors of the humidity and oxygen transmitter test the oxygen concentration in a free state, the oxygen concentration in a free state and the oxygen concentration in a mixed state, output signals of the two sensors are subjected to electrical processing such as amplification, filtering and linearization correction, the humidity and the oxygen concentration in the sample gas are calculated by a microprocessor, and finally, standard current or voltage signals in direct proportion to the humidity and the oxygen concentration of the sample gas are output.

Technical Field

The invention belongs to the technical field of petrochemical industry, and particularly relates to an online volatile organic compound monitoring system.

Background

Volatile Organic Compounds (VOCs) are known under the chemical name VOCs (vollatile organic compounds), compounds with a boiling point of 50-250 ℃, saturated vapor pressure of more than 133.32Pa at room temperature, and one type of organic compounds existing in the air as vapor at room temperature, according to the definition of the world health organization. The VOCs have complex components, more than 300 VOCs are detected at present, and can be further divided into alkanes, aromatic hydrocarbons, alkenes, halocarbons, esters, aldehydes, ketones and other compounds according to different chemical structures, and the VOCs are organic pollutants which are ubiquitous and complex in atmosphere, water quality, soil and other sediments. The toxicity, irritation and carcinogenesis of the Chinese medicinal composition have great influence on human health, and can cause damage to human such as nerve, lung, blood, kidney, liver and metabolism.

Therefore, people pay more attention to the research on the existence, source, distribution rule, migration and transformation of volatile organic compounds in the environment and the influence of the volatile organic compounds on human health, the emission monitoring of the volatile organic compounds is urgent, and the industrial source of the volatile organic compounds is the main source of the emission of VOCs;

according to the current environmental protection standard, on-site measurement data needs to be continuously analyzed, and data is intercepted and needs to be analyzed and transmitted to relevant units of an environmental protection bureau in time; according to the problems of low factor content, large water content and high corrosivity of on-site VOC smoke detection. The analysis system can be more reliable and can be more truly applied to real-time monitoring of organic matters discharged by various industrial fixed pollution sources. The analysis system and the instrument have stable and reliable performance, high automation degree and wide detection range.

Disclosure of Invention

To solve the problems set forth in the background art described above. The invention provides an online volatile organic compound monitoring system, which has the characteristics that an analysis system is more reliable and is more truly applied to real-time monitoring of organic compounds discharged by various industrial fixed pollution sources, and the analysis system and an instrument have stable and reliable performance, high automation degree and wide detection range.

In order to achieve the purpose, the invention provides the following technical scheme: an online volatile organic compound monitoring system comprises an online gas chromatograph, a smoke sampling probe subsystem, a pretreatment subsystem, a gas supply subsystem, a data acquisition and processing subsystem and a temperature and pressure flow subsystem; the online gas chromatograph mainly comprises a gas path and gas path control module, a column box and column box control module, a valve box and valve box control module, a detector and detector control module, a circuit module, an industrial personal computer module and a chromatographic module; the smoke sampling probe adopts a high-precision platinum resistance sensor, a temperature protection element and a back flushing unit, the temperature is controlled to be 200 ℃ at most, and components such as a sampling pipe, a filter element and the like are made of high-temperature resistant materials; the pretreatment subsystem adopts an integral heating box for heating, all pretreatment components are arranged in the heating box and consist of a secondary filter, a high-temperature air pump, a pneumatic control stop valve, an adjusting needle valve, a flowmeter and other components, and then the heat tracing box is introduced into the analyzer; the air supply subsystem comprises a zero gas generator and a hydrogen generator, the zero gas generator is an air source purifying treatment device, and the hydrogen generator is a high-sensitivity fuzzy control device and an automatic flow tracking device; the data acquisition and processing subsystem consists of a central unit, an upper computer (industrial personal computer) and VOC on-line continuous monitoring system monitoring software; the temperature and pressure flow subsystem is a temperature and pressure flow integrated monitor and a humidity and oxygen transmitter, wherein the temperature and pressure flow integrated monitor is based on the differential pressure measurement principle of the traditional pitot tube, the humidity and oxygen transmitter takes a microprocessor as a core, an ion current and humidity sensor as a measurement unit, and the reference voltage of the two sensors is controlled by a software PID technology.

As a preferred technical scheme of the online volatile organic compound monitoring system, the online gas chromatograph adopts a chromatographic technique to analyze and detect the non-methane total hydrocarbon components and the benzene, the toluene and the xylene, and is used for monitoring the concentration changes of the non-methane total hydrocarbon components and the benzene, the toluene and the xylene in the pipeline.

As the preferred technical scheme of the volatile organic compound on-line monitoring system, the smoke sampling probe adopts a high-temperature heat tracing technology and has the functions of automatic heat tracing temperature control, sampling stop, automatic back flushing and full-flow calibration.

As a preferred technical scheme of the online volatile organic compound monitoring system, the pretreatment subsystem completes the multi-stage treatment of the sample gas, so that the analysis instrument can obtain the clean and condensation-free sample gas which meets the requirements, and the long-term reliable operation of the analysis instrument is ensured.

As a preferred technical scheme of the online volatile organic compound monitoring system, the zero-gas generator carries out catalytic cracking on total hydrocarbons in compressed air to generate zero-level air with less than 0.1PPM (PPM) of hydrocarbons (measured by methane), the hydrocarbons are converted into carbon dioxide and water vapor in a de-hydrocarbon furnace containing a catalyst, and then the carbon dioxide and the water vapor are filtered and removed again to obtain ideal zero-level air.

As the preferred technical scheme of the online volatile organic compound monitoring system, the hydrogen generator enables the pressure stability precision range to be better than 0.001 MPa; the electrolytic cell adopts transition metal element catalysis technology, and the hydrogen purity is enabled to reach the oxygen content less than 3PPM and the water content dew point temperature less than minus 40 ℃ through multi-stage purification, the electrolytic cell is used for providing GC-3100 chromatograph carrier gas, FID detector combustion gas and FID detector combustion-supporting gas, a gas supply system continuously provides stable gas supply pressure and flow, and continuous online operation of an analytical instrument can be ensured.

As a preferred technical scheme of the online volatile organic compound monitoring system, the data acquisition and processing subsystem obtains upper computer software to summarize all gas concentration information and working state information, has the functions of generating reports, storing data, inquiring historical records, communicating with environmental protection departments in a networking mode and the like, and realizes acquisition of samples with different volumes by configuring sampling quantitative rings with different volumes, so that online analysis and detection of samples with different concentrations at treatment outlets are realized.

As a preferred technical scheme of the online volatile organic compound monitoring system, the temperature and pressure flow integrated monitor adopts an S-shaped pitot tube detection head, a pitot tube probe is inserted into a pipeline during measurement, the central axis of the probe is positioned in the center of an overflowing section and is consistent with the direction of a streamline, a full-pressure side hole of the probe is opposite to incoming flow, a static-pressure side hole is opposite to incoming flow, full-pressure static pressure is respectively transmitted to a sensor, and the sensor measures a differential pressure value, namely dynamic pressure.

As a preferred technical scheme of the online volatile organic compound monitoring system, the sensors of the humidity and oxygen transmitter test the oxygen concentration in a free state, the oxygen concentration in a free state and the oxygen concentration in a mixed state, after electrical processing such as amplification, filtering, linearization correction and the like is carried out on output signals of the two sensors, a microprocessor calculates the humidity and the oxygen concentration in a sample gas, and finally a standard current or voltage signal which is in direct proportion to the humidity and the oxygen concentration of the sample gas is output.

Compared with the prior art, the invention has the beneficial effects that: the on-line gas chromatograph adopts a chromatographic separation detection technology, has wide detection range and high detection sensitivity, and can effectively monitor the concentration change of non-methane total hydrocarbons before the emission of flue gas; the measurement signal is sent into the data acquisition and processing subsystem, through analog signal transmission to the DCS system, realizes the unmanned on duty continuous monitoring operation of job site, and this system has field data real-time transmission function, accessible DCS system monitoring test result trend of change, and the whole set of system simple structure simultaneously, dynamic range is wide, and the real-time nature is strong, and the network deployment is nimble, and the running cost is low, and the system adopts modular structure simultaneously, and the combination is convenient.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

The invention provides a technical scheme that: an online volatile organic compound monitoring system comprises an online gas chromatograph, a smoke sampling probe subsystem, a pretreatment subsystem, a gas supply subsystem, a data acquisition and processing subsystem and a temperature and pressure flow subsystem; the online gas chromatograph mainly comprises a gas path and gas path control module, a column box and column box control module, a valve box and valve box control module, a detector and detector control module, a circuit module, an industrial personal computer module and a chromatographic module; the smoke sampling probe adopts a high-precision platinum resistance sensor, a temperature protection element and a back flushing unit, the temperature is controlled to be 200 ℃ at most, and components such as a sampling pipe, a filter element and the like are made of high-temperature resistant materials; the pretreatment subsystem adopts an integral heating box for heating, all pretreatment components are arranged in the heating box and consist of a secondary filter, a high-temperature air pump, a pneumatic control stop valve, an adjusting needle valve, a flowmeter and other components, and then the heat tracing box is introduced into the analyzer; the air supply subsystem comprises a zero gas generator and a hydrogen generator, the zero gas generator is an air source purifying treatment device, and the hydrogen generator is a high-sensitivity fuzzy control device and an automatic flow tracking device; the data acquisition and processing subsystem consists of a central unit, an upper computer (industrial personal computer) and VOC on-line continuous monitoring system monitoring software; the temperature-pressure flow subsystem is a temperature-pressure flow integrated monitor and a humidity and oxygen transmitter, wherein the temperature-pressure flow integrated monitor is based on the differential pressure measurement principle of the traditional pitot tube, the humidity and oxygen transmitter takes a microprocessor as a core, an ion flow and humidity sensor as a measurement unit, the reference voltages of the two sensors are controlled by a software PID technology, an online gas chromatograph adopts a chromatographic separation detection technology, the detection range is wide, the detection sensitivity is high, and the concentration change of non-methane total hydrocarbons before the emission of flue gas can be effectively monitored; the measurement signal is sent into the data acquisition and processing subsystem, through analog signal transmission to the DCS system, realizes the unmanned on duty continuous monitoring operation of job site, and this system has field data real-time transmission function, accessible DCS system monitoring test result trend of change, and the whole set of system simple structure simultaneously, dynamic range is wide, and the real-time nature is strong, and the network deployment is nimble, and the running cost is low, and the system adopts modular structure simultaneously, and the combination is convenient.

Specifically, an online gas chromatograph adopts a chromatographic technique to analyze and detect non-methane total hydrocarbon components and benzene, toluene and xylene, is used for monitoring the change of the concentration of the non-methane total hydrocarbon components and the concentration of the benzene, the toluene and the xylene in a pipeline, adopts a solution scheme of two quantitative rings, a six-way valve, a ten-way valve, a switching valve, a chromatographic column for separating methane, a total hydrocarbon chromatographic column and a FID detector, realizes higher test cost performance on the premise of ensuring that all performance indexes reach the national standard, and has the specific working principle that a sample is pumped into the quantitative rings through a pump for quantification, the six-way valve and the ten-way valve are switched simultaneously, the sample in the total hydrocarbon quantitative rings rapidly passes through the total hydrocarbon column to reach the FID detector, the concentration of the total hydrocarbon is measured, the sample in the methane quantitative rings passes through a filling column, the sample is separated in the filling column, the methane passes through the filling column to reach the FID, measuring the concentration of methane, simultaneously switching the six-way valve and the ten-way valve to the original positions, purging the non-methane total hydrocarbons still remained in the packed column to an outlet by using a back flushing mode, completing detection, calculating the content of the non-methane total hydrocarbons according to the difference value of the content of the total hydrocarbons and the content of the methane, greatly shortening the analysis period, wherein the detection limit of the total hydrocarbons is 0.03mg/m3, the detection limit of the methane is 0.03mg/m3, and the requirement of the standard HJ/T38 can be met; also has: the method has the advantages that the FID detector is redesigned and processed, the sensitivity level of the detector is improved, a unique electronic pressure control unit is used, flow path control and temperature control are optimized, analysis precision is improved, real-time environment temperature and pressure compensation are achieved, the method is suitable for various environment conditions, a special valve box design is achieved, not only is waste gas of a fixed pollution source supported, but also environment air is supported, an automatic calibration function is achieved, periodic automatic calibration and quality control points can be set, response time is short, analysis time is short, an instrument is supported to conduct circulating monitoring on a plurality of working condition points, modular design and functional blocks are achieved, a function module, a built-in industrial personal computer and a touch screen design can be customized according to customer requirements, web remote operation is supported, signal butt joint with various pretreatment equipment at the front section is supported, and data output is supported to be connected with the industrial personal computer.

Specifically, the flue gas sampling probe is high temperature heat tracing technology, possesses automatic heat tracing accuse temperature, sampling end, automatic blowback, takes the function of full flow mark, has: special probe of flue gas sampling, box heat preservation thickness reaches 30mm, whole flow path heat tracing more than 180 ℃, does not have temperature condensation point, sample gas flow path stainless steel, crosses filter core and cavity special design (patent technology), more possesses quick dismantlement function, high temperature pneumatic valve stop function, the gaseous heat tracing of blowback, the dust blowback effect is better, possesses the sample, the blowback, the probe mark gas is markd the function, sealed pad is graphite material, the characteristics of the whole stainless steel material of cavity.

Specifically, the pretreatment subsystem completes the multi-stage treatment of the sample gas, so that the analysis instrument can obtain the clean and condensation-free sample gas which meets the requirements, and the long-term reliable operation of the analysis instrument is ensured.

Specifically, the zero-order generator carries out catalytic cracking on total hydrocarbons in the compressed air to generate zero-order air with less than 0.1PPM (PPM) of hydrocarbons (calculated by methane), the hydrocarbons are converted into carbon dioxide and water vapor in a de-hydrocarbon furnace containing a catalyst, and then the carbon dioxide and the water vapor are filtered and removed again to obtain ideal zero-order air.

Specifically, the hydrogen generator enables the pressure stability precision range to be better than 0.001 MPa; the electrolytic cell adopts transition metal element catalysis technology, and the hydrogen purity is enabled to reach the oxygen content less than 3PPM and the water content dew point temperature less than minus 40 ℃ through multi-stage purification, the electrolytic cell is used for providing GC-3100 chromatograph carrier gas, FID detector combustion gas and FID detector combustion-supporting gas, a gas supply system continuously provides stable gas supply pressure and flow, and continuous online operation of an analytical instrument can be ensured.

Specifically, the data acquisition and processing subsystem obtains upper computer software to summarize all gas concentration information and working state information, has the functions of generating reports, storing data, inquiring historical records, communicating with environmental protection departments in a networking mode and the like, and realizes acquisition of samples with different volumes by configuring sampling quantitative rings with different volumes, so that online analysis and detection of samples with different concentrations at treatment outlets are realized.

Specifically, the temperature and pressure flow integrated monitor adopts an S-shaped pitot tube detection head, a pitot tube probe is inserted into a pipeline during measurement, the central axis of the probe is positioned in the center of an overflowing section and is consistent with the direction of a streamline, a full-pressure side hole of the probe is opposite to incoming flow, a static-pressure side hole is opposite to incoming flow, full-pressure static pressure is respectively transmitted to a sensor, and the sensor measures a differential pressure value, namely dynamic pressure.

Specifically, the sensors of the humidity and oxygen transmitter test the oxygen concentration in a free state, the oxygen concentration in a free state and the oxygen concentration in a mixed state, after electrical processing such as amplification, filtering, linearization correction and the like is carried out on output signals of the two sensors, a microprocessor calculates the humidity and the oxygen concentration in the sample gas, and finally a standard current or voltage signal which is in direct proportion to the humidity and the oxygen concentration of the sample gas is output.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.