SURVEYING THERMAL FLUID DISTRIBUTION SYSTEMS

previous VELOCITY MODIFIED FLOWMETERS

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. 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.

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.

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.

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.

METERING PROGRAM: A successful metering program requires the following:

• Specification and installation of meter systems.
• Scheduled maintenance and calibration of meter systems.
• Scheduled collection, reduction, and analysis of data.
• Management support of the metering program.

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