Proceedings

It is proposed to integrate heat pumps to generate low pressure steam which can be used to
preheat sewage sludge in a Cambi THP plant with two-stage preheating.
The proposal includes two key points. The first is to use water heat from CHP to generate low
pressure steam via heat pumps; the second is to clarify that it needs work in a two stage
preheating THP system which can be Cambi’s conventional two-stage preheating THP or
Cambi’s new THP system which has no flash steam from reactors by adding a dedicated
second stage heater to accommodate steam from heat pumps. For both of them inlet
temperature of reactors can be improved higher than 100°C and then reduce total new
steam consumption.
Respectively, based on design data of a project mainly treating SAS (75% SAS), the modelling
demonstrates a reduction of 36% steam consumption and achieves a self-sufficient state (i.e.
no external fuel needed, all steam required will be raised from CHP’s waste heat boilers and
from heat pumps thermally driven by LTHW).