CHAPTER 8. SURVEYING THERMAL FLUID DISTRIBUTION SYSTEMS
1. INTRODUCTION. Fuel usage records are often the only reliable source for
estimating the consumption of energy used by a thermal fluid distribution
system and the processes served by that system. This accounting process does
not provide knowledge of when and where energy is consumed or how efficiently
it is produced. Properly selected flowmeters, which provide time-based
consumption patterns are required to successfully survey and manage a thermal
fluid distribution system.
1.1 Plant Level Meters. Accurate metering of fuel, feedwater, condensate,
and steam or high temperature water produced and exported is required to
manage a boiler plant. This level of metering provides boiler efficiencies
and overall plant input/output efficiencies. Also, superheaters and
desuperheaters can be monitored and more efficiently operated. Export meters
provide overall consumption of energy used by the customers, including system
losses. Peak energy usage and time of day usage are quantified and analyzed.
1.2 Trunkline Meters. Trunkline meters are installed in the main
distribution system to determine energy use by distinct areas of a facility.
Where possible, areas should be defined by specific customer to achieve
greater accountability. Usage profiles from trunkline meters can determine
where, when, and how efficiently energy is used. Unusually large system
losses may also be identified. An optimum distribution configuration is
determined based on energy demand profiles. Trunkline metering also provides
pressure drop analyses for a system.
1.3 Portable Meters. Portable meters are installed and removed without
interrupting service. Individual process or building loads are profiled for
troubleshooting or planning and design purposes. Line loss tests are done
using portable meters. Caution must be taken if using two meters for line
loss tests. The loss measured may be below the accuracy of the meters.
Economic analyses of energy conservation projects are more accurate with the
use of data from portable meters.
1.4 Condensate Meters. Condensate meters can be used to infer steam loads by
quantifying the amount of condensate returning to the steam plant. Condensate
meters are lower cost than steam meters, they do not require pressure or
temperature compensation, they are generally more reliable than steam meters,
and they require less maintenance. However, condensate meters should be used
with caution, since steam may be consumed in processes or lost through leaks
or steam traps. Additionally, if the condensate return system is in poor
condition, a significant portion of the total condensate may be lost through
leaks. Consequently, the amount of condensate measured may be significantly
less than the amount of steam actually used.
A successful metering program requires the following:
a. Specification and installation of meter systems.
Scheduled maintenance and calibration of meter systems.
c. Scheduled collection, reduction, and analysis of data.
Management support of the metering program.