Design and Construction of a High-Volume Flow Gas Metering Facility

Abstract

Introduction The need for a high volumetric rate natural gas proving facility has become more evident recently. The value of natural gas transferred has risen dramatically, and the inadequacies of the standard means of measurement have become more apparent. Natural gas use, material, and energy balances also require more precise calibration of flowmeters. A meter proving loop facility was therefore built, and a critical flow nozzle proving capability was installed to prove meters to 40 MMSCF/D (1.1327 × 10(6) m3/D). A description of the system and some results obtained with orifice meters and other commercial meters are shown. SYSTEM LOCATION AND CONSTRUCTION A proving facility must necessarily have an adequate volumetric through-put and adequate pressure to operate the critical flow nozzles. The site chosen was the Sand Hills Plant, South and West of Odessa, Texas, operated by Warren Petroleum Company (a wholly owned subsidiary of Gulf Oil Corp.). The line chosen for flow-verification was a residue gas product line delivering a nominal 40 MMSCF/D (1.1327 × 10(6) m3/D). A criterion that had to be satisfied was that the test system will not interrupt the normal delivery of product when in use. A simple schematic is shown in Figure 1. Though the system is folded for construction ease it is noted that it is basically a parallel loop to an existing flow system in which valves are used to transfer the added flow piping to a series connection. Additionally, since Valve 1 can be used for piping to a series connection. Additionally, since Valve 1 can be used for flow control, flow may be partially diverted to divide the flow between the two parallel loops without limiting the flow when operating the loop with critical flow nozzles for meter proving. CRITICAL FLOW NOZZLES Six critical flow nozzles conforming to ISO specifications (Ref. 1) for shape were purchased from Flow Measurement Systems, Longmont, CO, and calibrated for discharge coefficient by Colorado Engineering Experiment Station, Inc., Nunn, CO over the pressure and Reynold's number (Re) range of interest: 400–1000 psig (2.76–6.89 MPa) and 4 to 15 × 10(6) Re. Some properties of the nozzles are shown in Table 1. Table 1 Nozzle Specifications MeanCD = A+BRe(-1/2)Re × 10–6 No. Throat D, in (mm) A B1 .4383 (11.133) .989205 -3.215 6.585 2 .6495 (16.497) .991425 -4.7 10.24 3 .851 (21.615) .994279 -3.44 13.61 4 1.0621 (26.977) .994142 1.94 17.20 5 1.180 (29.972) .993791 -7.67 19.38 6 1.4390 (36.550) .991394 6.6 22.65 CD = Discharge Coefficient Re = Reynolds No All calibrations certified traceable to NBS.