SPECIAL DESIGNED HEAT EXCHANGER, LIGHTWEIGHT MODULAR CONCEPT IN CORROSION RESISTANT MATERIALS FOR WASTE INCINERATION INDUSTRY.

Modern municipal waste plants commonly dispose of municipal waste through burning (incineration) of the waste. The flue gasses from these incineration plants are usually processed further to remove harmful and corrosive components and dust, which is formed in each incineration plant during the burning process. In many cases also heat is recovered to keep operating cost as low as possible. A common unwanted phenomenon in the waste incineration industry is the forming of corrosive fumes during the incineration process. When the flue gasses are cooled down during the treatment process, temperature can drop below the dew point and cause corrosive components to condensate in the system, causing severe corrosions problems in certain parts of the installation.

Case History
The municipal waste incineration plant "Twence Afvalverwerking" was familiar with the corrosion problems. Every 3 - 4 years the heat exchanger in the flue gas duct had to be replaced due to corrosion problems. A additional problem was caused by the fact that the heat exchanger had a weight of 5000 kg and is placed in a flue gas channel 40 meter above the ground.       

Solution with modular design:
Geurts International, a heat transfer equipment specialist, with extensive experience in the municipal waste industry was asked to design a new heat exchanger. The replacement had to become a light weight corrosion resistant construction, which could be fitted in the existing space of the original heat exchanger.

To improve the durability of the heat exchanger corrosion resistant material (Alloy 59) was chosen for construction. This is expected to show a significant increase in the maintenance intervals.

To enable easy installation, handling (and possible replacement) the heat exchanger is developed according to a modular design Because of this modular design, the total weight was decreased considerably, to one third of the original weight at 1600 kg. In addition the heat exchanger can be rebuild piece by piece with elements, which have a maximum weight of 116 kg per element. The replacement at "Twence" could be done without having to take the roof off the building, saving enormous cost and effort. Future maintenance will also be simplified, allowing for easy replacement of a possibly corroded element of the heat exchanger, because of the modular design. Without having to take the whole heat exchanger out of the flue gas system. This will allow for savings on maintenance cost and limited down time of the installation.