In the continuous emission monitoring system for flue gas, the temperature pressure flow integrated machine plays a crucial role as the "vanguard". It can be directly installed on the flue without extracting flue gas, and can measure the three key parameters of temperature, pressure, and flow rate of flue gas in real time and online, providing a data foundation for environmental supervision and process optimization.
1、 Core principle: Divide and conquer, merge into one
The technical essence of the temperature pressure flow integrated machine lies in its use of different physical principles to measure three parameters separately, and finally integrate them through internal calculations.
Temperature measurement principle
Platinum resistance temperature sensors are usually used. Its core is to utilize the deterministic change in resistance value of platinum wire with temperature variation. The sensor extends into the flue, directly sensing the temperature of the flue gas and converting this change into precise electrical signals, thereby achieving real-time monitoring of the flue gas temperature.
Principle of pressure measurement
Pressure measurement mainly focuses on static pressure. Sensors (usually high-performance silicon piezoresistive sensors) sense the pressure exerted by smoke on them and convert it into electrical signals. In order to adapt to the pressure fluctuations in the flue, the equipment has the ability to measure positive and negative pressure (i.e. the pressure conditions before and after the induced draft fan).
Principle of flow velocity measurement
This is the most critical aspect of technology, and the mainstream technology uses differential pressure method, specifically the principle of S-shaped pitot tube. There are two symmetrical pressure tapping holes on the probe: one facing the airflow and sensing the total pressure; A person facing away from the airflow, feeling the static pressure. When smoke flows, a differential pressure value proportional to the square of the flow velocity will be generated between two pressure tapping holes. By measuring this small differential pressure and compensating for it with the measured temperature and pressure data, the real-time flow rate of the flue gas can be calculated using a built-in algorithm.
2、 Internal structure: Born for harsh environments
In order to work stably in flue environments with high temperature, high humidity, high corrosion, and high dust, the temperature pressure flow integrated machine has been carefully designed in terms of structure.
Core probe: As a component that directly contacts smoke, it is usually made of high-quality corrosion-resistant materials such as Hastelloy. Internally integrated with temperature sensors, pressure gauges, and differential pressure gauges, the structure is compact.
Backblowing cleaning unit: This is the "lifeline" that ensures long-term stable operation. The system will automatically inject clean compressed air or nitrogen into the pressure hole of the probe regularly (such as every few hours) to blow away the dust blocked in the hole and prevent measurement failure.
Transmitter unit: This is the "brain" of the device. It is installed outside the flue and is responsible for receiving signals from all sensors, performing temperature and pressure compensation calculations, ultimately displaying flow rate, flow rate, and other results, and outputting standard signals to the data acquisition system.
Heating unit: For flue gas with high moisture content, the probe is usually equipped with a heating function to prevent water vapor from condensing inside the probe, causing corrosion and measurement errors.
3、 Typical application: Defense line for protecting environmental protection and efficiency
The data of the temperature pressure flow integrated machine is the core basis for multiple processes.
Environmental emission monitoring: Flow rate and temperature are key parameters for calculating the total emissions of pollutants such as sulfur dioxide and nitrogen oxides. Without accurate flow rates, it is impossible to convert pollutant concentrations into accurate emissions, and environmental supervision and fees cannot be discussed.
Process control: Provide important feedback information for combustion equipment such as boilers and kilns. By monitoring the flow rate and temperature of flue gas, operators can optimize combustion efficiency and reduce energy consumption.
Assessment of governance facilities: Evaluate the operational performance of environmental protection facilities such as desulfurization towers and dust collectors. For example, by monitoring the pressure difference before and after the facility (calculated from static pressure), it is possible to determine whether the bag filter is clogged and whether the resistance of the desulfurization tower is normal, thereby guiding maintenance work.
In summary, the temperature pressure flow integrated machine has achieved reliable sensing of flue gas operating parameters in harsh industrial environments through its clever multi-sensor fusion design and robust protective structure.