Definitions.

All terms used in this subpart not defined below are given the meaning in the Act and in subpart A of this part. Acid gas means a gas stream of hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ) that has been separated from sour natural gas by a sweetening unit. Natural gas means a naturally occurring mixture of hydrocarbon and nonhydrocarbon gases found in geologic formations beneath the earth's surface. The principal hydrocarbon constituent is methane. Onshore means all facilities except those that are located in the territorial seas or on the outercontinental shelf. Reduced sulfur compounds means H 2 S, carbonyl sulfide (COS), and carbon disulfide (CS 2 ). Sulfur production rate means the rate of liquid sulfur accumulation from the sulfur recovery unit. Sulfur recovery unit means a process device that recovers element sulfur from acid gas. Sweetening unit means a process device that separates the H 2 S and CO 2 contents from the sour natural gas stream. Total SO 2 equivalents means the sum of volumetric or mass concentrations of the sulfur compounds obtained by adding the quantity existing as SO 2 to the quantity of SO 2 that would be obtained if all reduced sulfur compounds were converted to SO 2 (ppmv or kg/dscm (lb/dscf)). EThe sulfur emission rate expressed as elemental sulfur, kilograms per hour (kg/hr) [pounds per hour (lb/hr)], rounded to one decimal place. RThe sulfur emission reduction efficiency achieved in percent, carried to one decimal place. SThe sulfur production rate, kilograms per hour (kg/hr) [pounds per hour (lb/hr)], rounded to one decimal place. XThe sulfur feed rate from the sweetening unit (i.e., the H 2 S in the acid gas), expressed as sulfur, Mg/D(LT/D), rounded to one decimal place. YThe sulfur content of the acid gas from the sweetening unit, expressed as mole percent H 2 S (dry basis) rounded to one decimal place. ZThe minimum required sulfur dioxide (SO 2 ) emission reduction efficiency, expressed as percent carried to one decimal place. Z i refers to the reduction efficiency required at the initial performance test. Z c refers to the reduction efficiency required on a continuous basis after compliance with Z i has been demonstrated. [50 FR 40160, Oct. 1, 1985, as amended at 65 FR 61773, Oct. 17, 2000]