Heat pump-based steam systems

1. The steam is produced at the lowest possible
pressure by a high-temperature heat pump.
The COP and, therefore, the electricity consumption
of the heat pump is directly related to the
temperature lift.

2. The operation is not as sensitive to sudden
changes in load, so, thermal mass is not strictly
required. Steam accumulators or other types of 
thermal energy storages may, however, become
attractive to offer flexibility and to exploit the
fluctuations in the electricity price.

3. With a lower pressure on the steam system,
the capacity of the temperature control valve is
reduced. While these valves are usually oversized,
valve capacity must be checked when lowering
the steam pressure as replacement of the valve seat
or a complete valve might be needed.

4. The heat exchanger may have to be replaced
with a bigger heat exchanger due to a smaller
temperature difference. A minimum temperature
difference with the process will probably be the lower
limit for lowering the pressure.

5. The lower steam pressure will cause stall
conditions more often. In order for the steam
condensate to be correctly discharged, replacing
the steam trap with a vacuum pump may be required.

6. As the temperature of the condensate is lower,
flash losses on the condensate recovery system 
are reduced. High degrees of subcooling of the
condensate return may, however, cause hammering
at the mixing point with flash steam.