[Code of Federal Regulations]
[Title 40, Volume 9]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR63.11]
[Page 60-62]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 63_NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR
SOURCE CATEGORIES--Table of Contents
Subpart A_General Provisions
Sec. 63.11 Control device requirements.
(a) Applicability. The applicability of this section is set out in
Sec. 63.1(a)(4).
(b) Flares. (1) Owners or operators using flares to comply with the
provisions of this part shall monitor these control devices to assure
that they are operated and maintained in conformance with their designs.
Applicable subparts will provide provisions stating how owners or
operators using flares shall monitor these control devices.
(2) Flares shall be steam-assisted, air-assisted, or non-assisted.
(3) Flares shall be operated at all times when emissions may be
vented to them.
(4) Flares shall be designed for and operated with no visible
emissions, except for periods not to exceed a total of 5 minutes during
any 2 consecutive hours. Test Method 22 in appendix A of part 60 of this
chapter shall be used to determine the compliance of flares with the
visible emission provisions of this part. The observation period is 2
hours and shall be used according to Method 22.
(5) Flares shall be operated with a flame present at all times. The
presence of a flare pilot flame shall be monitored using a thermocouple
or any
[[Page 61]]
other equivalent device to detect the presence of a flame.
(6) An owner/operator has the choice of adhering to the heat content
specifications in paragraph (b)(6)(ii) of this section, and the maximum
tip velocity specifications in paragraph (b)(7) or (b)(8) of this
section, or adhering to the requirements in paragraph (b)(6)(i) of this
section.
(i)(A) Flares shall be used that have a diameter of 3 inches or
greater, are nonassisted, have a hydrogen content of 8.0 percent (by
volume) or greater, and are designed for and operated with an exit
velocity less than 37.2 m/sec (122 ft/sec) and less than the velocity
Vmax, as determined by the following equation:
Vmax=(XH2-K1)* K2
Where:
Vmax=Maximum permitted velocity, m/sec.
K1=Constant, 6.0 volume-percent hydrogen.
K2=Constant, 3.9(m/sec)/volume-percent hydrogen.
XH2=The volume-percent of hydrogen, on a wet basis, as
calculated by using the American Society for Testing and Materials
(ASTM) Method D1946-77. (Incorporated by reference as specified in Sec.
63.14).
(B) The actual exit velocity of a flare shall be determined by the
method specified in paragraph (b)(7)(i) of this section.
(ii) Flares shall be used only with the net heating value of the gas
being combusted at 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 at 7.45 M/scm (200 Btu/scf) or greater if the flares is
non-assisted. The net heating value of the gas being combusted in a
flare shall be calculated using the following equation:
[GRAPHIC] [TIFF OMITTED] TR04MY98.004
Where:
HT=Net heating value of the sample, MJ/scm; where the net
enthalpy per mole of offgas is based on combustion at 25 [deg]C and 760
mm Hg, but the standard temperature for determining the volume
corresponding to one mole is 20 [deg]C.
K=Constant=
[GRAPHIC] [TIFF OMITTED] TR04MY98.005
where the standard temperature for (g-mole/scm) is 20 [deg]C.
Ci=Concentration of sample component i in ppmv on a wet
basis, as measured for organics by Test Method 18 and measured for
hydrogen and carbon monoxide by American Society for Testing and
Materials (ASTM) D1946-77 or 90 (Reapproved 1994) (incorporated by
reference as specified in Sec. 63.14).
Hi=Net heat of combustion of sample component i, kcal/g-mole
at 25 [deg]C and 760 mm Hg. The heats of combustion may be determined
using ASTM D2382-76 or 88 or D4809-95 (incorporated by reference as
specified in Sec. 63.14) if published values are not available or
cannot be calculated.
n=Number of sample components.
(7)(i) Steam-assisted and nonassisted flares shall be designed for
and operated with an exit velocity less than 18.3 m/sec (60 ft/sec),
except as provided in paragraphs (b)(7)(ii) and (b)(7)(iii) of this
section. The actual exit velocity of a flare shall be determined by
dividing by the volumetric flow rate of gas being combusted (in units of
emission standard temperature and pressure), as determined by Test
Method 2, 2A, 2C, or 2D in appendix A to 40 CFR part 60 of this chapter,
as appropriate, by the unobstructed (free) cross-sectional area of the
flare tip.
(ii) Steam-assisted and nonassisted flares designed for and operated
with an exit velocity, as determined by the method specified in
paragraph (b)(7)(i) of this section, 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).
(iii) Steam-assisted and nonassisted flares designed for and
operated with an exit velocity, as determined by the method specified in
paragraph (b)(7)(i) of this section, less than the velocity
Vmax, as determined by the method specified in this
paragraph, but less than 122 m/sec (400 ft/sec) are allowed. The maximum
permitted velocity, Vmax, for flares complying with this
paragraph shall be determined by the following equation:
Log10(Vmax)=(HT+28.8)/31.7
[[Page 62]]
Where:
Vmax=Maximum permitted velocity, m/sec.
28.8=Constant.
31.7=Constant.
HT=The net heating value as determined in paragraph (b)(6) of
this section.
(8) Air-assisted flares shall be designed and operated with an exit
velocity less than the velocity Vmax. The maximum permitted
velocity, Vmax, for air-assisted flares shall be determined
by the following equation:
Vmax=8.71 = 0.708(HT)
Where:
Vmax=Maximum permitted velocity, m/sec.
8.71=Constant.
0.708=Constant.
HT=The net heating value as determined in paragraph
(b)(6)(ii) of this section.
[59 FR 12430, Mar. 16, 1994, as amended at 63 FR 24444, May 4, 1998; 65
FR 62215, Oct. 17, 2000; 67 FR 16605, Apr. 5, 2002]