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)
X is the sulfur feed rate in the acid gas, Mg/d (long ton/day)
NR 440.684(7)(g)(g) The continuous emission monitoring systems required in sub. (7) (b) 1., (b) 3., and (c) shall be subject to the emission monitoring requirements of s. NR 440.13. For conducting the continuous emission monitoring system performance evaluation required by s. NR 440.13 (3), Performance Specification 2 of 40 CFR part 60, Appendix B, incorporated by reference in s. NR 440.17, shall apply, and Method 6 of 40 CFR part 60, Appendix A, incorporated by reference in s. NR 440.17, shall be used for systems required by par. (b). NR 440.684(8)(a)(a) Records of the calculations and measurements required in subs. (3) (a) and (b) and (7) (a) to (g) shall be retained for at least 2 years following the date of the measurements by owners and operators subject to this section. This requirement is included under s. NR 440.07 (5). NR 440.684(8)(b)(b) Each owner or operator shall submit a written report of excess emissions to the department semiannually. For the purpose of these reports, excess emissions are defined as: NR 440.684(8)(b)1.1. Any 24-hour period (at consistent intervals) during which the average sulfur emission reduction efficiency (R) is less than the minimum required efficiency (Z). NR 440.684(8)(b)2.2. For any affected facility electing to comply with the provisions of sub. (7) (b) 2., any 24-hour period during which the average temperature of the gases leaving the combustion zone of an incinerator is less than the appropriate operating temperatures determined during the most recent performance test in accordance with the provisions of sub. (7) (b) 2. Each 24-hour period shall consist of at least 96 temperature measurements equally spaced over the 24 hours. NR 440.684(8)(c)(c) To certify that a facility is exempt from the control requirements of these standards, each owner or operator of a facility with a design capacity less than 2 LT/D of H2S in the acid gas (expressed as sulfur) shall keep, for the life of the facility, an analysis demonstrating that the facility’s design capacity is less than 2 LT/D of H2S expressed as sulfur. NR 440.684(8)(d)(d) Each owner or operator who elects to comply with sub. (7) (e) shall keep, for the life of the facility, a record demonstrating that the facility’s design capacity is less than 150 LT/D of H2S expressed as sulfur. NR 440.684(9)(9) Optional procedure for measuring hydrogen sulfide in acid gas-tutwiler procedure. NR 440.684(9)(a)(a) General. The Tutwiler procedure may be used to measure hydrogen sulfide in acid gas in accordance with the Gas Engineer’s Handbook, first edition, second printing, Fuel Gas Engineering Practices, page 6/25, incorporated by reference in s. NR 440.17. When an instantaneous sample is desired and H2S concentration is 10 grains per 1000 cubic foot or more, a 100 ml Tutwiler burette is used. For concentrations less than 10 grains, a 500 ml Tutwiler burette and more dilute solutions are used. In principle this method consists of titrating hydrogen sulfide in a gas sample directly with a standard solution of iodine.