The condenser's function is based on spherical particles creating a very large absorbing surface. Through specially designed nozzles, small water droplets (spherical particles) are created that combined comprise the total absorption surface.
The flue gas is sprayed intensively with a large number of nozzles, and the water droplets' absorbing surface constitutes the mechanical heat exchanger. The heat from the gas is absorbed by the liquid and transferred via the plate heat exchanger to the process in question, such as a district heating system.
When the moist gas is cooled quickly, it can no longer carry moisture in its gaseous state, but instead condenses, meaning that it precipitates as a liquid. The more the gas is cooled, the greater the amount of condensate generated.
The condensate can be regarded as a measure of heat recovery. By measuring the volume of condensate, the volume of energy transferred can be easily calculated. The condensate is used as process water that cools the gas in a closed system. Excess condensate is discharged from the system to the recipient through the water treatment system.
district heat temperature of 50°C and a fuel with a water content of 55% results in a condenser output of 32% of the boiler output. If the boiler output power is 1 MW, the condenser produces 0.32 MW.
The particle concentration in the process water is determined by the relation between the input dust volume and the volume of condensate formed during the same period. This means that if the flue gas is cooled less, because the district heat return increases, for example, the concentration will increase. This is offset by the fact that there is always a flow to the water treatment system that is much greater than the estimated maximum condensate flow. From the water treatment system, the surplus is always fed back to the process water, thus ensuring that a pre-determined particle concentration in the process water can be guaranteed. When condensation ceases, fresh water would need to be added, since the condenser consumes water when the gas becomes saturated. However, there is a system for this situation that does not require fresh water. See page 13, Operation with electrostatic precipitator and condenser disconnected.
The gas is sprayed in a gently sloping tube that is equipped with a large number of nozzles. The water runs along the bottom of the tube to a collection vessel where the pH value may be adjusted. From this vessel, the water is pumped into a plate heat exchanger that transfers the absorbed energy. The water is then fed once again to the nozzles to be finally collected in the tank. The entire process thus takes place in a closed system in which only the volume of condensate generated is discharged for water treatment.
Through the intensive water sprinkling of the gas, the condenser also functions as an efficient scrubber. The coarse dust particles are cleaned from the gas and fed to the water treatment unit according to the above description. This scrubbing effect is important for the ability of the electrostatic precipitator to separate the finer dust particles from the gas.
The combination of a large heat exchanger and a high degree of heat transfer between the mist and the gas results in efficient heat transfer with high performance.
There is no clogging and no enrichment of flue dust, with the resulting problematic depositions, since all condenser surfaces are always wet.
Thermal and chemical loads are minimized, and the equipment handles the most aggressive gases without incurring damage.
All replaceable components, such as pumps and valves, are of standard design and readily available.
The simple design and function means fewer repairs that can easily be performed by a local contractor.