1. Background Information
VOCs, volatile organic compounds, refer to chemical substances with melting points below room temperature and boiling points between 50 and 260°C. VOCs are extremely harmful to humans, and when the concentration of volatile organic compounds in indoor air is too high, it is easy to cause acute poisoning. In recent years, with the continuous deepening of people's awareness of green environmental protection, the government and enterprises have paid more attention to online monitoring, prevention, and governance of VOCs.
VOCs monitoring is currently the key project of atmospheric monitoring. Due to the complex composition of exhaust VOCS and the harsh monitoring environment, the requirements for monitoring equipment are also very high.
2. Application IntroductionAs the power part of gas sampling of VOCs online monitoring instrument, micro air pump is a vital equipment. The micro-pump transmits the environmental waste gas to the analysis unit for analysis and detection through the sampling gas path. In addition, the pretreatment of VOCs online monitoring equipment will also involve the part of condensation and water removal, and it is necessary to use a micro liquid pump to discharge the water of the condenser.
1. Main steps of VOCs online monitoring:
2. Brief description of the principle of VOCs online monitoring:(1) The sample gas is transmitted to the analysis unit through a micro air pump, which includes sampling and pretreatment. The pretreatment process filters and removes the sample gas, and the liquid pump is responsible for discharging the condensed and dehydrated liquid;
(2) The analysis unit detects and analyzes the processed sample gas and then discharges it. At the same time, the analysis results are fed back to the collection module, and then uploaded to the monitoring system or mobile APP through the wireless DTU module;
(3) The monitoring system can send a signal to the control module through the DTU module to indirectly control the start and stop of the sampling pump, adjust the flow rate, or control the start and stop of other units.
(1) The selected closed container needs to have a certain ability to withstand negative pressure, and it is best to have a discharge channel at the bottom of the container;
3. Notes on matters needing attention:
(2) The selected liquid level sensor needs to have certain corrosion resistance, and some use scenarios must not contaminate the medium, etc.
3. Difficulties of the project
1. On-line monitoring requires continuous operation of the micro air pump around the clock, long life and maintenance-free;
2. The complex composition of the sample gas requires the micro-pump to have a certain anti-corrosion ability, and has extremely high requirements on the quality and material of the pump;
3. The severe monitoring environment requires that the micropump can work under high temperature and withstand high temperature medium;
4. The micro-pump needs to be able to remotely control the start and stop, adjust the flow rate, and online feedback the operation of the pump;
4. Solutions1. Hilin Technology's product system includes: micro vacuum pump, micro pressure pump and micro liquid pump, and the liquid pump can be dry-run. In the above case, Hilin Technology can provide sampling pump and liquid pump at the same time;
2. Hilin Technology's full range of miniature pumps have strict life tests. Each model is divided into three versions according to life and performance: "simplified version, standard version, quality version". The quality version of some models has a continuous working life of 10,000 hours. Life test conditions of the micro pump: "In a clean and non-corrosive laboratory, the pump is fully loaded (the suction port is blocked, the exhaust port is open to the atmosphere), and runs continuously around the clock; ambient temperature: 5 ℃ ~ 33 ℃, depending on the climate Fluctuations; relative humidity 30% to 90%, fluctuating with the climate.". At the same time, all series of pumps are equipped with self-protection functions, overload protection, overheat protection, etc.;
3. The gas contact materials of the entire series of Hailin Technology miniature diaphragm pumps are made of reinforced nylon and EPDM rubber materials, which have good corrosion resistance to common acids and alkali gas liquids;
4. The working temperature and medium temperature tolerance of conventional models of Hilin Technology miniature pumps are around 0-50℃, but our company can also provide high and low temperature customized services, such as: customizing high temperature media within 100℃, customizing 60℃ and above High temperature environment, etc.;
5. Hilin Technology's full range of miniature pumps have a version with a speed control function. The pumps have a variety of speed control methods. Customers can choose different speed control versions according to the use. The speed control methods are roughly divided into: voltage signal, frequency signal , touchscreen speed control and PWM signal speed control, etc. In the above case, you can choose frequency speed control, voltage speed control or PWM speed control to facilitate remote flow adjustment. Most models have a version with remote start and stop function, combined with the situation of the user's on-site control unit to achieve remote start and stop of the pump. In addition, some model versions also have RS-485 communication function to achieve remote monitoring of working conditions, such as: 50 series and 60 series top version.