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Chemical Dosing System
Skid-mounted chemical storage tanks and metering pumps
Process
- Product
- Chemical
01Chemical storage tank with agitator
Stores the chemical to be dosed, either neat or diluted, and an agitator mixes it evenly when it is dissolved or diluted in water. A motor and gearbox on the tank top turn an impeller at the end of the shaft. The tank is made of a material that suits the chemical and stands inside a bund wall in case of leaks.
Main components
- Tank shell
- Agitator (motor, gearbox, impeller)
- Level gauge
- Outlet valve
02Measuring tank
A small tank that takes a measured batch of chemical from the storage tank. The level gauge shows how much has been charged and used, and water can be added here to set the dosing strength.
Main components
- Measuring tank
- Level gauge
- Inlet and outlet valves
- Support stand
03Suction strainer and calibration column
A Y-strainer on the metering pump suction line keeps debris in the chemical from lodging in the pump check valves. The calibration column is a graduated cylinder on the pump suction side. With the tank valve closed, the pump draws from the column for a set time, and the drop in level shows the actual pump output.
Main components
- Y-strainer
- Calibration column (graduated cylinder)
- Isolation valves
- Suction piping
04Metering pump
Delivers a set quantity of chemical at a steady rate. Diaphragm pumps are common, and the dose is adjusted by stroke length or speed. A standby pump keeps dosing going if one pump stops.
Main components
- Diaphragm pumps
- Suction and discharge valves
- Pump base
- Standby pump
05Pulsation dampener, back-pressure and relief valves
A diaphragm pump pushes the liquid out stroke by stroke, so the discharge flow pulses. The pulsation dampener takes up the pressure swings in its gas space to smooth the flow, and the back-pressure valve holds the discharge pressure steady so that the dose does not drift. If the line is blocked and the pressure rises, the relief valve opens and sends the chemical back to the tank through the return line.
Main components
- Pulsation dampener
- Back-pressure valve
- Relief valve
- Pressure gauge and return line
06Injection quill
The nozzle that carries the chemical into the boiler or cooling water main. The quill reaches to the middle of the pipe and releases the chemical into the centre of the flow, which prevents wall corrosion and local concentration. An isolation valve and a check valve ahead of the quill keep main-line water from flowing back into the chemical line.
Main components
- Injection quill (nozzle tube)
- Connection flange
- Isolation ball valve
- Check valve
Selected deliveries
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01POSCO E&C -
02POSCO E&C -
03Doosan Heavy Industries -
04Doosan Heavy Industries -
05Doosan Heavy Industries
Chemical dosing systems inject water treatment chemicals in set quantities into boiler water, cooling water and process water systems. They are built around chemical storage tanks and metering pumps.
Our main deliveries have been to power plants built by Doosan Heavy Industries (now Doosan Enerbility) in Korea and abroad: the Shin Hanul nuclear power plant (2011), Barakah nuclear power plant units 1 to 4 in the UAE (2012) and the Mong Duong 2 coal-fired power plant in Vietnam (2012). For BHI we supplied chemical dosing and sampling systems for FINEX plant No. 2 (2009) and No. 3 (2016).