Section NR 440.18 - General control device requirements(1) INTRODUCTION. This section contains requirements for control devices used to comply with applicable sections of this chapter and chs. NR 445 to 484. The requirements are placed in this section for administrative convenience and only apply to facilities covered by sections or chapters referring to this section.(2) FLARES. Subsections (3) through (6) apply to flares.(3)(a) Flares shall be designed for and operated with no visible emissions as determined by the methods specified in sub. (6), except for periods not to exceed a total of 5 minutes during any 2 consecutive hours.(b) Flares shall be operated with a flame present at all times, as determined by the methods specified in sub. (6).(c) Flares shall be used only with the net heating value of the gas being combusted being 11.2 MJ/scm (300 Btu/scf) or greater if the flare is steam-assisted or air-assisted; or with the net heating value of the gas being combusted being 7.45 MJ/scm (200 Btu/scf) or greater if the flare is nonassisted. The net heating value of the gas being combusted shall be determined by the methods specified in sub. (6).(d)1. Steam-assisted and nonassisted flares shall be designed for and operated with an exit velocity, as determined by the methods specified in sub. (6) (d), less than 18.3 m/sec (60 ft/sec), except as provided in subds. 2. and 3.2. Steam-assisted and nonassisted flares designed for and operated with an exit velocity, as determined by the methods specified in sub. (6) (d), equal to or greater than 18.3 m/sec (60 ft/sec) but less than 122 m/sec (400 ft/sec) are allowed if the net heating value of the gas being combusted is greater than 37.3 MJ/scm (1,000 Btu/scf).3. Steam-assisted and nonassisted flares designed for and operated with an exit velocity, as determined by the methods specified in sub. (6) (d), less than the velocity, Vmax, as determined by the method specified in sub. (6) (e), and less than 122 m/sec (400 ft/sec) are allowed.(e) Air-assisted flares shall be designed and operated with an exit velocity less than the velocity, Vmax, as determined by the method specified in sub. (6) (f).(f) Flares used to comply with this section shall be steam-assisted, air-assisted, or nonassisted.(4) Owners or operators of flares used to comply with the provisions of this section shall monitor these control devices to ensure that they are operated and maintained in conformance with their designs. Applicable sections below provide provisions stating how owners or operators of flares shall monitor these control devices.(5) Flares used to comply with provisions of this section shall be operated at all times when emissions may be vented to them.(6)(a) Method 22 of Appendix A, 40 CFR part 60, incorporated by reference in s. NR 440.17(1), shall be used to determine the compliance of flares with the visible emission provisions of this section. The observation period is 2 hours and shall be used according to Method 22.(b) The presence of a flare pilot flame shall be monitored using a thermocouple or any other equivalent device to detect the presence of a flame.(c) The net heating value of the gas being combusted in a flare shall be calculated using the following equation: See PDF for diagram
where:
HT is the net heating value of the sample, MJ/scm; where the net enthalpy per mole of offgas is based on combustion at 25°C and 700 mm Hg, but the standard temperature for determining the volume corresponding to one mole is 20°C;
K is the conversion constant, 1.740 10-7
See PDF for diagram
where the standard temperature for (g-mole)/scm is 20°C;
Ci is the concentration of sample component i in ppm on a wet basis, as measured for organics by Method 18 in 40 CFR part 60, Appendix A, incorporated by reference in s. NR 440.17(1), and measured for hydrogen and carbon monoxide by ASTM D1946-90, incorporated by reference in s. NR 440.17(2) (a) 24.
Hi is the net heat of combustion of sample component i, kcal/(g-mole) at 25°C and 760 mm Hg. The heats of combustion may be determined using ASTM D2382-88 or D4809-95, incorporated by reference in s. NR 440.17(2) (a) 30. and 61., if published values are not available or cannot be calculated.
(d) The actual exit velocity of a flare shall be determined by dividing the volumetric flow rate (in units of standard temperature and pressure), as determined as appropriate by Reference Method 2, 2A, 2C, or 2D of Appendix A, 40 CFR part 60, incorporated by reference in s. NR 440.17, by the unobstructed (free) cross sectional area of the flare tip.(e) The maximum permitted velocity, Vmax, for flares complying with sub. (3) (d) 3. shall be determined by the following equation: Log10 (Vmax) = (HT + 28.8)/31.7
where:
Vmax is the maximum permitted velocity, m/sec
28.8 = constant
31.7 = constant
HT is the net heating value as determined in par. (c)
(f) The maximum permitted velocity, Vmax, for air-assisted flares shall be determined by the following equation: Vmax = 8.706 + 0.7084 (HT)
where:
Vmax is the maximum permitted velocity, m/sec
8.706 = constant
0.7084 = constant
HT is the net heating value as determined in par. (c)
Wis. Admin. Code Department of Natural Resources NR 440.18
Cr. Register, September, 1990, No. 417, eff. 10-1-90; am. (6) (a), (c), (e) and (f), Register, July, 1993, No. 451, eff. 8-1-93; am. (6) (c), Register, December, 1995, No. 480, eff. 1-1-96; CR 06-109: am. (6) (a) and (c) Register May 2008 No. 629, eff. 6-1-08.