The development of a microprocessor based instrument for calculating mass, volume, and energy of natural gas
Collins, Michael G.
Feustel, Edward A.
Master of Science
This Thesis describes the design of a microprocessor based industrial instrument which is used for natural gas metering. It is named the PC-8. By using equations and standards of the American Gas Association (AGA) Reports numbers three and five, the FC-8 instrument calculates the volumetric flow rate, the mass flow rate and the energy flow rate of natural gas flowing in a pipeline. The primary volumetric metering standard is the orifice plate. The FC-8 dynamically calculates the modeling factors for the orifice plate i.e. Reynolds factor (Fp) and expansion factor (Y). This technique improves orifice metering over traditional volumetric metering methods because in the past Fr and Y were assumed constant at the time of meter design (AGA3). By measuring gas density and following the rules of AGA5 the FC-8 calculates the mass flow rate of natural gas. By measuring the specific gravity of natural gas and using Caldwell's equation also found in AGA5, the FC-8 derives the energy flow rate in dekatherms. A dekatherm is one million BTU's. The design of the FC-8 is followed from its conception to its inception by starting with the systems definition and following through to a working prototype. The system definition is anaylized so the hardware architecture may be formalized and the equations optimized for efficient execution. Several number formats are developed and a floating point arithmetic package is designed to manipulate thes formats. A study is performed on several microprocessing systems and the processor best suited is selected. After a processor is selected, the input/output structure and protocol is designed. The final element discussed is the development of the FC-8 executive program.