NR 440.682 HistoryHistory: Cr. Register, September, 1990, No. 417, eff. 10-1-90; am. (4) (b) 3. a., Register, July, 1993, No. 451, eff. 8-1-93; correction in (4) (b) and (d) made under s. 13.93 (2m) (b) 7., Register, November, 1999, No. 527; CR 06-109: am. (3) (f) and (4) (h) 1. and 2. Register May 2008 No. 629, eff. 6-1-08. NR 440.684NR 440.684 Onshore natural gas processing: SO2 emissions. NR 440.684(1)(1) Applicability and designation of affected facilities. NR 440.684(1)(a)(a) The provisions of this section are applicable to the following affected facilities that process natural gas: each sweetening unit, and each sweetening unit followed by a sulfur recovery unit. NR 440.684(1)(b)(b) Facilities that have a design capacity less than 2 long tons per day (LT/D) of hydrogen sulfide (H2S) in the acid gas (expressed as sulfur) are required to comply with sub. (8) (c) but are not required to comply with subs. (3) to (7). NR 440.684(1)(c)(c) The provisions of this section are applicable to facilities located on land and include facilities located onshore which process natural gas produced from either onshore or offshore wells. NR 440.684(1)(d)(d) The provisions of this section apply to each affected facility identified in par. (a) which commences construction or modification after January 20, 1984. NR 440.684(1)(e)(e) The provisions of this section do not apply to sweetening facilities producing acid gas that is completely reinjected into oil-or-gas-bearing geologic strata or that is otherwise not released to the atmosphere. NR 440.684(2)(a)1.1. “Acid gas” means a gas stream of hydrogen sulfide (H2S) and carbon dioxide (CO2) that has been separated from sour natural gas by a sweetening unit. NR 440.684(2)(a)2.2. “Natural gas” means a naturally occurring mixture of a hydrocarbon and nonhydrocarbon gases found in geologic formations beneath the earth’s surface. The principal hydrocarbon constituent is methane. NR 440.684(2)(a)3.3. “Onshore” means all facilities except those that are located in the territorial seas or on the outercontinental shelf. NR 440.684(2)(a)4.4. “Reduced sulfur compounds” means hydrogen sulfide (H2S), carbonyl sulfide (COS), and carbon disulfide (CS2). NR 440.684(2)(a)5.5. “Sulfur production rate” means the rate of liquid sulfur accumulation from the sulfur recovery unit. NR 440.684(2)(a)6.6. “Sulfur recovery unit” means a process device that recovers element sulfur from acid gas. NR 440.684(2)(a)7.7. “Sweetening unit” means a process device that separates the H2S and CO2 contents from the sour natural gas stream. NR 440.684(2)(a)8.8. “Total SO2 equivalents” means the sum of volumetric or mass concentrations of the sulfur compounds obtained by adding the quantity existing as SO2 to the quantity of SO2 that would be obtained if all reduced sulfur compounds were converted to SO2, ppmv or kg/dscm (lb/dscf). NR 440.684(2)(b)(b) As used in this section, all symbols not defined in this subsection have the meanings given them in s. NR 440.03. NR 440.684(2)(b)1.1. “E” is the sulfur emission rate expressed as elemental sulfur in kg/hr (lb/hr), rounded to one decimal place. NR 440.684(2)(b)2.2. “R” is the sulfur emission reduction efficiency achieved in percent carried to one decimal place. NR 440.684(2)(b)3.3. “S” is the sulfur production rate in kg/hr (lb/hr), rounded to one decimal place. NR 440.684(2)(b)4.4. “X” is the sulfur feed rate from the sweetening unit, that is, the H2S in the acid gas, expressed as sulfur, Mg/d (long ton/day), rounded to one decimal place. NR 440.684(2)(b)5.5. “Y” is the sulfur content of the acid gas from the sweetening unit, expressed as mole percent H2S (dry basis) rounded to one decimal place. NR 440.684(2)(b)6.6. “Z” is the minimum required sulfur dioxide (SO2) emission reduction efficiency, expressed as percent carried to one decimal place. Zi refers to the reduction efficiency required at the initial performance test. Zc refers to the reduction efficiency required on a continual basis after compliance with Zi has been demonstrated. NR 440.684(3)(a)(a) During the initial performance test required by s. NR 440.08 (2), each owner or operator shall achieve, at a minimum, an SO2 emission reduction efficiency (Zi) to be determined from Table 1 based on the sulfur feed rate (X) and the sulfur content of the acid gas (Y) of the affected facility. NR 440.684(3)(b)(b) After demonstrating compliance with the provisions of par. (a), the owner or operator shall achieve, at a minimum, an SO2 emission reduction efficiency (Zc) to be determined from Table 2 based on the sulfur feed rate (X) and the sulfur content of the acid gas (Y) of the affected facility. NR 440.684(4)(a)1.1. To determine compliance with the standards for sulfur dioxide specified in sub. (3) (a), during the initial performance test as required by s. NR 440.08, the minimum required sulfur dioxide emissions reduction efficiency (Z) is compared to the emission reduction efficiency (R) achieved by the sulfur recovery technology. NR 440.684(4)(a)2.2. Following the initial determination of compliance as required by s. NR 440.08, any subsequent compliance determinations that may be required by the department shall compare R to Zc. NR 440.684(4)(b)(b) The emission reduction efficiency (R) achieved by the sulfur recovery technology shall be determined using the procedures in sub. (5) (c) 1. NR 440.684(5)(a)(a) In conducting the performance tests required in s. NR 440.08, the owner or operator shall use as reference methods and procedures the test methods in Appendix A of 40 CFR part 60, incorporated by reference in s. NR 440.17, or other methods and procedures as specified in this subsection, except as provided in s. NR 440.08 (2). NR 440.684(5)(b)(b) During a performance test required by s. NR 440.08, the owner or operator shall determine the minimum required reduction efficiencies (Z) of SO2 emissions as required in sub. (3) (a) and (b) as follows: where:
X is the average sulfur feed rate, Mg/d (long ton/day)
Qa is the average volumetric flow rate of acid gas from sweetening unit, dscm/day (dscf/day)
Y is the average H2S concentration in acid gas feed from sweetening unit, percent by volume, expressed as a decimal
K is (32kg S/kg-mole)/((24.04 dscm/kg-mole)(1000kg S/Mg)) = 1.331 x 10-3 Mg/dscm for metric units, and is (32 lb S/lb-mole)/((385.36 dscf/lb-mole)(2240 lb S/long ton)) = 3.707 x 10-5 long ton/dscf for English units
NR 440.684(5)(b)2.2. The continuous readings from the process flowmeter shall be used to determine the average volumetric flow rate (Qa) in dscm/day (dscf/day) of the acid gas from the sweetening unit for each run. NR 440.684(5)(b)3.3. The Tutwiler procedure in sub. (9) or a chromatographic procedure following ASTM E260-96, incorporated by reference in s. NR 440.17 (2) (a) 75., shall be used to determine the H2S concentration in the acid gas feed from the sweetening unit. At least one sample per hour, at equally spaced intervals, shall be taken during each 4-hour run. The arithmetic mean of all samples shall be the average H2S concentration (Y) on a dry basis for the run. By multiplying the result from the Tutwiler procedure by 1.62 ×10-3, the units gr/100 scf are converted to volume percent. NR 440.684(5)(b)4.4. Using the information from par. (b) 1. and 3., Tables 1 and 2 shall be used to determine the required initial (Zi) and continuous (Zc) reduction efficiencies of SO2 emissions. NR 440.684(5)(c)1.1. The emission reduction efficiency (R) achieved by the sulfur recovery technology shall be computed for each run using the following equation: NR 440.684(5)(c)2.2. The level indicators or manual soundings shall be used to measure the liquid sulfur accumulation rate in the product storage tanks. Readings taken at the beginning and end of each run, the tank geometry, sulfur density at the storage temperature and sample duration shall be used to determine the sulfur production rate (S) in kg/hr (lb/hr) for each run. NR 440.684(5)(c)3.3. The emission rate of sulfur shall be computed for each run as follows: where:
E is the emission rate of sulfur per run, kg/hr (lb/hr)
Ce is the concentration of sulfur equivalent (SO2 + reduced sulfur), g/dscm (lb/dscf)
Qsd is the volumetric flow rate of effluent gas, dscm/hr (dscf/hr)
K1 is a conversion factor, 1000 g/kg (7000 gr/lb)
NR 440.684(5)(c)4.4. The concentration (Ce) of sulfur equivalent shall be the sum of the SO2 and TRS concentrations, after being converted to sulfur equivalents. For each run and each of the test methods specified in this paragraph, the sampling time shall be at least 4 hours. Method 1 shall be used to select the sampling site. The sampling point in the duct shall be at the centroid of the cross- section if the area is less than 5 m2 (54 ft2) or at a point no closer to the walls than 1 m (39 in.) if the cross-sectional area is 5 m2 (54 ft2) or more and the centroid is more than 1 m (39 in.) from the wall. NR 440.684(5)(c)4.a.a. Method 6 shall be used to determine the SO2 concentration. Eight samples of 20 minutes each shall be taken at 30-minute intervals. The arithmetic average shall be the concentration for the run. The concentration shall be multiplied by 0.5 × 10-3 to convert the results to sulfur equivalent. NR 440.684(5)(c)4.b.b. Method 15 shall be used to determine the TRS concentration from reduction-type devices or where the oxygen content of the effluent gas is less than 1.0% by volume. The sampling rate shall be at least 3 liters/min (0.1 ft3/min) to insure minimum residence time in the sample line. Sixteen samples shall be taken at 15-minute intervals. The arithmetic average of all the samples shall be the concentration for the run. The concentration in ppm reduced sulfur as sulfur shall be multiplied by 1.333 × 10-3 to convert the results to sulfur equivalent. NR 440.684(5)(c)4.c.c. Method 16A or 15 shall be used to determine the reduced sulfur concentration from oxidation-type devices or where the oxygen content of the effluent gas is greater than 1.0% by volume. Eight samples of 20 minutes each shall be taken at 30-minute intervals. The arithmetic average shall be the concentration for the run. The concentration in ppm reduced sulfur as sulfur shall be multiplied by 1.333 × 10-3 to convert the results to sulfur equivalent. NR 440.684(5)(c)4.d.d. Method 2 shall be used to determine the volumetric flow rate of the effluent gas. A velocity traverse shall be conducted at the beginning and end of each run. The arithmetic average of the 2 measurements shall be used to calculate the volumetric flow rate (Qsd) for the run. For the determination of the effluent gas molecular weight, a single integrated sample over the 4-hour period may be taken and analyzed or grab samples at 1-hour intervals may be taken, analyzed and averaged. For the moisture content, 2 samples of at least 0.10 dscm (3.5 dscf) and 10 minutes shall be taken at the beginning of the 4-hour run and near the end of the time period. The arithmetic average of the 2 runs shall be the moisture content for the run. NR 440.684(5)(d)(d) To comply with sub. (7) (d), the owner or operator shall obtain the information required by using the monitoring devices in par. (b) or (c). NR 440.684(7)(a)(a) The owner or operator subject to the provisions of sub. (3) (a) or (b) shall install, calibrate, maintain and operate monitoring devices or perform measurements to determine the following operations information on a daily basis: NR 440.684(7)(a)1.1. The accumulation of sulfur product over each 24-hour period: The monitoring method may incorporate the use of an instrument to measure and record the liquid sulfur production rate, or may be a procedure for measuring and recording the sulfur liquid levels in the storage tanks with a level indicator or by manual soundings with subsequent calculation of the sulfur production rate based on the tank geometry, stored sulfur density, and elapsed time between readings. The method shall be designed to be accurate with ± 2% of the 24-hour sulfur accumulation. NR 440.684(7)(a)2.2. The H2S concentration in the acid gas from the sweetening unit for each 24-hour period: At least one sample per 24-hour period shall be collected and analyzed using the method specified in sub. (5) (b) 3. The department may require the owner or operator to demonstrate that the H2S concentration obtained from one or more samples over a 24-hour period is within ± 20% of the average of 12 samples collected at equally spaced intervals during the 24-hour period. In instances where the H2S concentration of a single sample is not within ± 20% of the average of the 12 equally spaced samples, the department may require a more frequent sampling schedule. NR 440.684(7)(a)3.3. The average acid gas flow rate from the sweetening unit: The owner or operator shall install and operate a monitoring device to continuously measure the flow rate of acid gas. The monitoring device reading shall be recorded at least once per hour during each 24-hour period. The average acid gas flow rate shall be computed from the individual readings. NR 440.684(7)(a)5.5. The required sulfur dioxide emission reduction efficiency for the 24-hour period. The sulfur feed rate and the H2S concentration in the acid gas for the 24-hour period as applicable, shall be used to determine the required efficiency in accordance with the provisions of sub. (3) (b). NR 440.684(7)(b)(b) Where compliance is achieved through the use of an oxidation control system or a reduction control system followed by a continually operated incineration device, the owner or operator shall install, calibrate, maintain, and operate monitoring devices and continuous emission monitors as follows: NR 440.684(7)(b)1.1. A continuous monitoring system to measure the total sulfur emission rate (E) of SO2 in the gases discharged to the atmosphere. The SO2 emission rate shall be expressed in terms of equivalent sulfur mass flow rates kg/hr (lb/hr). The span of this monitoring system shall be set so that the equivalent emission limit of sub. (3) (b) will be between 30% and 70% of the measurement range of the instrument system. NR 440.684(7)(b)2.2. Except as provided in subd. 3.: A monitoring device to measure the temperature of the gas leaving the combustion zone of the incinerator, if compliance with sub. (3) (a) is achieved through the use of an oxidation control system or a reduction control system followed by a continually operated incineration device. The monitoring device shall be certified by the manufacturer to be accurate to within ± 1% of the temperature being measured. When performance tests are conducted under the provision of s. NR 440.08 to demonstrate compliance with the standards under sub. (3), the temperature of the gas leaving the incinerator combustion zone shall be determined using the monitoring device. If the volumetric ratio of sulfur dioxide to sulfur dioxide plus total reduced sulfur (expressed as SO2) in the gas leaving the incinerator is ≥ 0.98, then temperature monitoring may be used to demonstrate that sulfur dioxide emission monitoring is sufficient to determine total sulfur emissions. At all times during the operation of the facility, the owner or operator shall maintain the average temperature of the gas leaving the combustion zone of the incinerator at or above the appropriate level determined during the most recent performance test to ensure the sulfur compound oxidation criteria are met. Operation at lower average temperatures may be considered by the department to be unacceptable operation and maintenance of the affected facility. The owner or operator may request that the minimum incinerator temperature be reestablished by conducting new performance tests under s. NR 440.08. NR 440.684(7)(b)3.3. The owner or operator may, as an alternative to subd. 2., install, calibrate, maintain, and operate a continuous emission monitoring system for total reduced sulfur compounds as required in par. (d) in addition to a sulfur dioxide emission monitoring system. The sum of the equivalent sulfur mass emission rates from the 2 monitoring systems shall be used to compute the total sulfur emission rate (E). NR 440.684(7)(c)(c) Where compliance is achieved through the use of a reduction control system not followed by a continually operated incineration device, the owner or operator shall install, calibrate, maintain, and operate a continuous monitoring system to measure the emission rate of reduced sulfur compounds as SO2 equivalent in the gases discharged to the atmosphere. The SO2 equivalent compound emission rate shall be expressed in terms of equivalent sulfur mass flow rates kg/hr (lb/hr). The span of this monitoring system shall be set so that the equivalent emission limit of sub. (3) (b) will be between 30 and 70% of the measurement range of the system. NR 440.684(7)(d)(d) For those sources required to comply with pars. (b) and (c), the average sulfur emission reduction efficiency achieved (R) shall be calculated for each 24-hour clock interval. The 24-hour interval may begin and end at any selected clock time but shall be consistent. The 24-hour average reduction efficiency (R) shall be computed based on the 24-hour average sulfur production rate (S) and sulfur emission rate (E) using the equation in sub. (5) (c) 1. NR 440.684(7)(d)1.1. Data obtained from the sulfur production rate monitoring device specified in par. (a) shall be used to determine S. NR 440.684(7)(d)2.2. Data obtained from the sulfur emission rate monitoring systems specified in par. (b) or (c) shall be used to calculate a 24-hour average for the sulfur emission rate (E). The monitoring system shall provide at least one data point in each successive 15-minute interval. At least 2 data points shall be used to calculate each 1-hour average. A minimum of 18 1-hour averages shall be used to compute each 24-hour average. NR 440.684 NR 440.684(7)(e)(e) In lieu of complying with par. (b) or (c), those sources with a design capacity of less than 152 Mg/d (150 long ton/day) of H2S expressed as sulfur may calculate the sulfur emission reduction efficiency achieved for each 24-hour period by using the following equation: where:
R is the sulfur dioxide removal efficiency achieved during the 24-hour period, percent
K2 is a conversion factor, 0.02400 Mg/d per kg/hr (0.01071 long ton/day per lb/hr)
S is the sulfur production rate during the 24-hour period, kg/hr (lb/hr)
