The properties of tungsten trioxide SCR denitration catalyst will cause a direct effect on the whole denitration system, the different working conditions cause the different catalyst design; therefore, the scientific and reasonable choice of a catalyst form, amount and type is becoming the key of designing SCR denitration system. In this paper, we propose how the five kinds of working conditions affect tungsten trioxide SCR denitration catalyst.

 

1. High content of calcium

CaO will cause catalyst poisoning, it performance as that when the content of CaO is very high in the fly ash, or the flue gas has a high sulfur trioxide content, large amounts of calcium sulfate will easy to produce in the catalyst surface, they adhere to each other thus to form a bridge, and cause shielding of catalyst surface, thereby reducing catalyst activity.

 

2. High ash

Currently, the mainstream types of catalyst have been used are honeycomb, plate and corrugated plate. Among them, the plate exhibits more favorable advantage in a high fly ash condition; and corrugated plate shares a relatively low market, which is less than 5%. Generally, when the concentration of fly ash in flue gas is among 50~60g/Nm3 or even higher, choosing the plate which is not easy to plug fouling will bring more safety operation, due to the far greater cross-sectional area it has. However, when in a lower ash concentration, the plate catalyst will inquire 20%~40% more than the honeycomb under the same engineering conditions, thus resulting in initial purchase costs of the catalyst and other auxiliary parts increasing.

 

3. High temperature

The suitable temperature of tungsten trioxide SCR denitration catalyst is generally 300~400°C, however, even in this temperature range, a large amount of catalyst will be required to meet the basic denitration ratio. The amount of catalyst depends on the parameter like NOx concentration, gas flow, and denitration efficiency requirements.