脱硝粉煤灰中NH4HSO4在粉煤灰-水泥复合体系的留存释放规律及影响

通过外掺NH4HSO4的模拟手段,研究了脱硝粉煤灰中NH4HSO4在粉煤灰-水泥复合体系(简称复合体系)的留存与释放行为规律,以及二者对复合体系的影响.结果 表明:脱硝粉煤灰中的NH4HSO4在复合体系中分解,释放出氨气,部分留存在复合体系中.将30％脱硝粉煤灰掺入水泥中,所留存的NH4HSO4对复合体系pH值的降低程...

Retention and Release of NH4HSO4 in Denitration Fly Ash in Fly Ash Cement Composite System and Its Effect

The retention and release behavior of NH4HSO4 in fly ash cement composite system(composite system for short) and the influence of NH4HSO4 on the composite system was studied by means of simulation. The results show that NH4HSO4 in denitration fly ash decomposes in the composite system and releases ammonia, part of which remains in the composite system. When 30% denitration fly ash is added into cement, the remaining NH4HSO4has little effect on the pH value of the composite system, and it is concentrated in the first 1h. The influence of retained NH4HSO4 on cement hydration is also concentrated in the early stage, which reduces the hydration exothermic peak and delays the appearance of exothermic peak. With the continuous hydration of cement in the late stage, it has no effect on the hydration heat and hydration products of cement. With the increase of ammonia content, the release amount and content of ammonia in the composite system increase, and the retention ratio of NH+4 and NH3·H2O also increases; the release of ammonia leads to the increase of porosity and the number of macropores after hardening of the composite system; the increase of ammonia content in denitration fly ash, paste mixing and water cement ratio of the composite system will accelerate the release of ammonia.