eyc-tech Exhaust emission flow monitoring solution

eyc-tech Exhaust emission flow monitoring solution

eyc-tech Exhaust emission flow monitoring soluti

Industrial process environment such as chemical, petrochemical, electronics, optoelectronics, semiconductor, metal processing, wastewater treatment, deodorization, etc. Have an Air pollution problems with volatile organic compounds (VOCs), It mainly includes organic waste gas treatment, dust exhaust gas treatment, acid and alkali waste gas treatment, odor exhaust gas treatment and air sterilization and purification, etc. Mainly use the exhaust gas scrubber to treat harmful components and clean the exhaust gas, and must consider the flow rate (average/maximum value), temperature, humidity and corrosion of the exhaust gas; Its function is mainly to control the scattered VOCs, and continuously measure the flue gas flow rate, flue gas flow, flue gas temperature and pressure in the pipeline to reaching environmental protection. In order to comply with environmental emission standards and to achieve emissions to the EPA, flow monitoring of exhaust gas collection and emissions is extremely important.

Note: VOCs volatile organic compounds refer to organic compounds with a saturated vapor pressure greater than 70 Pa at normal temperature and a boiling point below 260 °C at ordinary pressure, or the vapor pressure is greater than or equal to 10 Pa at 20 °C with have corresponding volatility All organic compounds.

Exhaust gas treatment flow chart:

eyc-tech Exhaust gas treatment flow chart

Exhaust gas scrubber uses the contact between gas and liquid, and transporting gas from the contaminants into the liquid, then separate the clean gas from the contaminated liquid to achieve clean air, and use average flow measuring tube or pitot tube collocation differential pressure transmitter to achieve flow monitoring.

Practical application:
Semiconductor manufacturing or electronics frequently etched or cleaned with a large amount of inorganic acid-base solution or gas enthalpy, some chemicals are collected by the system due to volatilization or emissions, the semiconductor industry emission standards should confirm one of the two requirements for removal efficiency or total emissions. For example, pollutants such as nitric acid, hydrochloric acid, phosphoric acid, and hydrofluoric acid, the total emissions of the plant must be less than 0.6 kg/hr, the sulfuric acid needs to be less than 0.1 kg/hr, or the removal efficiency of the scrubber is over 95%.

Note: Unable to prove compliance with emission standards, the control conditions should meet the following requirements: Equipment washing cycle sink pH should be greater than 7、Wetting factor should be greater than 0.1 m2 /hr、Filled section empty tower dwell time should be greater than 0.5 seconds and the specific surface area of the filler should be greater than 90m2 / m3.

The composition of the exhaust gas scrubbing collection (dust collection) system can be slightly divided into the following:
Gas hood: Capture airborne contaminants to ensure minimum air volume to achieve the highest capture efficiency.
Windpipe: The pipeline that transports the airflow, making the system one, and the deposition of pollutants is avoided, and the pressure loss is too large.
Exhaust gas treatment equipment: Dispose of pollutants to meet the requirements of regulatory standards, such as consideration of pollutant concentration, pollutant characteristics, exhaust gas characteristics, environmental protection law requirements, Setting cost, operating costs, secondary pollution disposal, etc.
Chimney: Ensure that air pollutants emitted by the chimney are sufficient for diffusion, and height required to comply with the current provisions air pollutant discharge standards.

Reference values for different wind speed conditions in exhaust gas removal control:
Evaporation from a storage tank or liquid surface、grease dissolution, exhaust gas at no entity speed still in the air, control wind speed needs to be 0.3~0.5m/s.
Spray room, containers need Intermittent operation, low-speed conveyor belt, welding operation, plating solution storage tank、metal It acid solution cleaning, exhaust gas at a low speed, control wind speed needs to be 0.5~1.0m/s.
Shallow and Long and narrow spray booth、discharge port、comminutor、Conveyor belt (machine) loading and unloading bagging operation, exhaust gas diffuses in the air of rapid airflow in a lively, control wind speed needs to be 1.0~3.0m/s.
Attrition grinder、pestle mill、sand blast、drum polishing、exhaust gas is discharged into the fast moving air, Control wind speed needs to be 3.0~10m/s.

Consider the characteristics of exhaust gas have the following points: handling air volume、density、temperature、pressure、corrosive、water content、smelly odor、Inflammability、explosive nature、toxicity、stickiness、Therefore, it is necessary to choose high temperature resistance、corrosion resistant、resistant dust average flow measuring tube (pitot tube), can do it correct exhaust gas flow monitoring.

eyc-tech AFMT Average Flow Measuring Tube, operating pressure Max 10 bar, operating temperature Max. 250°C, Measuring medium / coefficient is air / flow coefficient (K) : 1, measuring tube use SUS316.
In the flow system, space problems often result in the inability to give enough straight pipe sections, causing serious turbulence problems.
AFMT can average the characteristics of the flow curve of the fluid in the pipeline.
eyc-tech AFMT  inserted into the duct(along with the whole diameter) to measure the flow. When the probe encounters the flow, will sense and get the average total pressure P1 in windward side and static pressure P2 in leeward.
AFMT then gets the flow velocity by measuring the difference between total pressure and static pressure (i.e.) dynamic pressure (∆P) and flow average velocity (V). Stainless steel housing, high temperature resistant, corrosion resistance, dust resistance, can measure micro flow rates. Usually collocation eyc-tech PHM33 Differential Pressure Transmitter measuring flow rate and flow rate in the calculation of flow rate in the calculation, principle uses very small amounts of gas, passing it over the airflow path of the sensor body, and combined with integrated circuit to convert into differential pressure signal, and use ModBus RS-485, MODBUS RTU communication protocol set can be transferred to PLC or Industrial PC for remote monitoring, calibration correction only need to correction differential pressure transmitter, avoid disassembling the upper flange of the pipeline.
Suitable for air pollution control or poor working conditions such as petrochemical industry、electronic industry exhaust gas exclusion, environmental protection engineering installation position is not limited.

eyc-tech AFMT Average Flow Measuring Tube ( Pitot tube ) used for exhaust gas scrubber installation diagram (below):

eyc-tech AFMT Average Flow Measuring Tube ( Pitot tube ) used for exhaust gas scrubber installation diagram

Another option is eyc-tech AFMS-160 S-type Pitot tube collocation PHM33 Differential Pressure Transmitter, operating pressure max 10 bar, operating temperature 800°C, measuring medium/coefficient is air/flow coefficient(K) : 0.84, measuring tube use SUS316, designed for measuring the flow velocity of the gas fluid in the chimney and the environment, prevents clogging of soot under harsh conditions, further rapid reaction treatment of smoke and sewage discharge procedures.
S-type pitot tube for measuring the local velocity of a fixed point, can be applied in scientific research、produce、surroundings protection、mine ventilation and tunnel construction, use S-type pitot tube to measure airflow velocity in the pipeline, it to determine flow and speed by conversion, easy to use and accurate, is a widely used method for measuring gas flow pressure. high temperature, corrosion-resistant, resistant dust, large, open tip design resists fouling, can be used in harsh environments, exhaust gas emission, environmental protection engineering.

eyc-tech AFMS-160 S-type Pitot tube used for exhaust gas scrubber installation diagram:

eyc-tech AFMS-160 S-type Pitot tube used for exhaust gas scrubber installation diagram

Exhaust emission removal solution, assisting many industries to improve the difficulty of flow control measurement, precise monitoring, emissions that meet environmental protection regulations and meet the requirements of applying to the Environmental Protection Agency, to protect the environment and maintain the safety and quality of life of all people.

Reference source : Taiwan Executive Yuan Environmental Protection Agency, fugitive emission control, air pollution prevention specialist training materials

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