Background
A combined heat and power (CHP) plant in Jiangsu Province is undergoing comprehensive upgrades to enhance boiler efficiency and optimize operations as part of its smart plant initiative. Given the complex and variable composition of the coal used, the plant must comply with the Water Pollution Prevention and Control Action Plan and the Pollutant Emission Permit Implementation Scheme. To achieve environmental targets, the plant is refining its desulfurization equipment and processes to implement a Zero Liquid Discharge (ZLD) system for wastewater.
Measurement Requirements
The desulfurization process typically follows a sequence of pre-treatment, concentration, and final solidification. Wastewater is initially pre-treated, then concentrated, and the remaining liquid is solidified to prevent discharge.
Since the amount of wastewater generated is relatively small, the plant employs flue gas evaporation for solidification after pre-treatment. A flowmeter is required between the pre-treatment stage and the evaporation tower to measure the flow rate of wastewater entering the drying unit. Accurate flow measurement supports operational adjustments and ensures effective desulfurization.
The system regulates wastewater injection into the drying tower at a steady flow rate of around 0.5 tons per hour, using a DN10 pipe diameter. The plant requires flowmeters that are resistant to corrosion, provide accurate readings, and offer stable performance.
Solution
After discussions with the customer, three electromagnetic flowmeters were installed at key points between the desulfurization unit and the drying tower to monitor wastewater flow. The desulfurization wastewater originates mainly from the absorber tower in the wet flue gas desulfurization (FGD) process. While pre-treatment removes large suspended solids, calcium, magnesium ions, and some heavy metals, the remaining wastewater contains high concentrations of chlorides and heavy metals, making it highly corrosive.
Given these conditions, the customer opted for corrosion-resistant, explosion-proof electromagnetic flowmeters to ensure durability and accuracy in this demanding environment.
Customer Benefits
Since the installation of the flowmeters in September 2023, the devices have demonstrated stable performance and precise measurements. The accurate data allows the plant to promptly adjust operational parameters, ensuring optimal desulfurization performance and improving production efficiency.
The customer also expressed satisfaction with the technical support and solutions provided during the selection, installation, and commissioning stages by the supplier’s service team.
Product Features
- Suitable for conductive fluids, particularly wastewater and chemical liquids.
- High accuracy: 0.5-level or 0.2-level precision.
- Capable of measuring low flow rates as slow as 0.1 m/s.
- Available in diameters ranging from DN4 to DN2000.
- Explosion-proof design with IP65 and IP68 protection ratings.
- Multiple communication options: RS485, HART, 4G, NB-IoT.
This successful case highlights the role of advanced instrumentation in environmental compliance and production efficiency at power plants, showing how well-chosen equipment can meet both regulatory requirements and operational needs.