VENAPCD RULE 74.15.1 BOILERS, STEAM GENER., & PROC. HEATERS

LAST REVISED 05/11/93

Rule 74.15.1 Boilers, Steam Generators, and Process Heaters

(Adopted 5/11/93)

A. Applicability

The provisions of this rule apply to any person owning

and/or operating a boiler, steam generator, or process

heater with a rated heat input capacity equal to or greater

than 1 million Btu per hour and less than 5 million Btu per

hour.

B. Requirements

1. No person shall allow the discharge into the

atmosphere, from any boiler, steam generator, or

process heater with an annual heat input rate of equal

to or greater than 1.8 x 109 Btu, oxides of nitrogen

(NOx) emissions in excess of 30 parts per million

volume (ppmv). Carbon monoxide (CO) emissions from

units subject to this rule shall not exceed 400 ppmv.

Units subject to the above provisions shall test for

compliance not less than once every 24 months.

2. A person operating any boiler, steam generator, or

process heater with an annual heat input rate of equal

to or greater than

0.3 x 109 Btu and less than 1.8 x 109 Btu shall comply

with one of the following requirements:

a. The unit shall be tuned every 6 months or after

750 hours of operation since the previous tuneup,

whichever occurs last, but in no case less than

once per calendar year. The unit shall be tuned

in accordance with the procedure described in

Attachment 1; or

b. The unit shall comply with the requirements of

Subsection B.1.

C. Exemptions

The provisions of Subsection B.1 of this rule shall not

apply to any unit operated on alternate fuel under the

following conditions:

1. Alternate fuel use is required due to the curtailment

of natural gas service to the individual unit by the

natural gas supplier. Alternate fuel use in this case

shall not exceed the period of natural gas curtailment.

2. Alternate fuel use is required to maintain the

alternate fuel system. Alternate fuel use in this case

shall not exceed 50 hours per year.

The provisions of Subsection B.2 of this rule shall not be

required for alternate fuel use.

D. Recordkeeping Requirements

1. Any person owning and/or operating a boiler, steam

generator, or process heater with an annual heat input

rate of less than

1.8 x 109 Btu and not complying with the requirements

of Subsection B.1 shall install a totalizing fuel meter

for each applicable unit and for each fuel. Meters

shall be accurate to + one (1) percent, as certified by

the manufacturer in writing. Fuel consumption for each

unit shall be compiled monthly into a rolling twelve

(12) calendar month report.

2. Any person subject to the provisions of Subsection

B.2.a shall submit a report to the Air Pollution

Control Officer (APCO) within twelve (12) months after

achieving compliance with Subsection B.2.a. Reports

shall continue to be submitted every twelve (12)

months. This report shall verify that each tune-up has

been performed and the results were satisfactory. The

report shall contain all information and or

documentation that the APCO may determine, in writing,

to be necessary.

3. Any person utilizing alternate fuel, pursuant to the

provisions of Subsection C.1 of this rule, shall

maintain daily records of each occurrence. Each record

shall include the type of fuel, the quantity of fuel,

and the duration of the occurrence.

4. All records required by Subsections D.1 and D.3 shall

be maintained for a period of four (4) years and shall

be available for inspection by the APCO upon request.

E. Test Methods

1. Compliance with the emission requirements in Section

B shall be determined using ARB Method 100 for Oxides

of Nitrogen, Carbon Monoxide, and Stack Gas Oxygen.

2. Emission tests resulting in compliance determinations

for the requirements of Subsection B.1 shall be

conducted on units in "As-found" operating condition.

However, no emission test for this rule shall be

conducted during start-up, shutdown or under breakdown

conditions.

3. The NOx parts per million emission limitation

specified in Subsection B.1. is expressed as nitrogen

dioxide. The limitations for both NOx and CO are

referenced at three (3) percent volume stack gas oxygen

on a dry basis averaged over 15 consecutive minutes.

F. Violations

1. Failure to comply with any provision of this rule

shall constitute a violation of this rule.

2. Any unit subject to the provisions of Subsection B.2

shall comply with the provisions of Subsection B.1 if

the unit operates during any rolling twelve (12) month

period at a total annual heat input rate greater than

the applicable annual heat input rate specified in

Subsection B.2.

3. Any unit previously operating at an annual heat input

rate of less than 0.3 x 109 Btu shall comply with the

applicable provisions of Subsection B.1 or Subsection

B.2 if the unit operates during any rolling twelve (12)

month period at a total annual heat input rate greater

than 0.3 x 109 Btu.

G. Definitions

1. "Annual Heat Input": The actual amount of heat

released by fuels burned in a unit during a twelve (12)

calendar month rolling period, based on the fuel's

higher heating value. The annual heat input shall be

calculated as the sum of the previous 12 monthly fuel

use rates multiplied by the fuel's higher heating

value.

2. "Boiler or Steam Generator": Any combustion equipment

fired with liquid and/or gaseous fuel and used to

produce steam or to heat water. Boiler or Steam

Generator does not include any unfired waste heat

recovery boiler that is used to recover sensible heat

from the exhaust of any combustion equipment.

3. "Process Heater": Any combustion equipment fired with

liquid and/or gaseous fuel and which transfers heat

from combustion gases to water or process streams.

Process Heater does not include any kiln or oven used

for drying, baking, cooking, calcining or vitrifying,

any unfired waste heat recovery heater that is used to

recover sensible heat from the exhaust of any

combustion equipment, or any fuel-fired degreasing or

metal finishing equipment.

4. "Rated Heat Input Capacity": The heat input capacity

specified on the nameplate of the combustion unit. If

the combustion unit has been altered or modified such

that its maximum heat input is different than the heat

input capacity specified on the nameplate, the new

maximum heat input shall be considered as the rated

heat input capacity. This alteration or modification

can be through either burner alteration or modification

or installation of a fixed orifice. The new maximum

heat input must be certified, in writing, by the

manufacturer or installer and engineering calculations

supporting the new maximum heat input rating must be

submitted to the APCO.

5. "Therm": 100,000 Btu.

6. "Unit": Any boiler, steam generator, or process

heater as defined in Subsections G.2 and G.3 of this

rule.

H. Increments of Progress

1. If total NOx emissions from all sources in this

District owned and operated by the same business equal

25 tons or more per year or the business owner/operator

has three or fewer units subject to Subsection B.1,

complete Authority to Construct applications shall be

submitted to the APCO by May 31, 1994, and final

compliance shall be demonstrated by May 31, 1995.

2. If total NOx emissions from all sources in this

District owned and operated by the same business are

less than 25 tons per year and the business

owner/operator has four or more units subject to the

requirements of Subsection B.1:

a. A compliance schedule shall be submitted to the

APCO for approval by May 31, 1994.

b. Final compliance for 25 percent of the units

shall be demonstrated by May 31, 1995 and for an

additional 25 percent each May 31 thereafter until

final compliance for all units is demonstrated by

May 31, 1998. Complete Authority to Construct

applications shall be submitted to the APCO at

least one year prior to the required compliance

date.

3. For units subject to Subsection B.2, final compliance

shall be demonstrated by November 30, 1994.

ATTACHMENT 1

Equipment Tuning Procedure

Nothing in this Equipment Tuning Procedure shall be construed to

require any act or omission that would result in unsafe

conditions or would be in violation of any regulation or

requirement established byfactory Mutual, Industrial Risk

Insurers, National Fire Prevention Association, California

Department of Industrial Relations (Occupational Safty and Health

Division), Federal Ocupational Safety and Health Administration,

or other relevant regulations and requirements.

1. Operate the unit at the firing rate most typical of normal

operation. If the unit experiences significant load

variations during normal operation, operate it at its

average firing rate.

2. At this firing rate, record stack gas temperature, oxygen

concentration, and CO concentration (for gaseous fuels) or

smoke-spot2 number (for liquid fuels), and observe flame

conditions after unit operation stabilizes at the firing

rate selected. If the excess oxygen in the stack gas is at

the lower end of the range of typical minimum values3, and

if the CO emissions are low and there is no smoke, the unit

is probably operating at near optimum efficiency - at this

particular firing rate. However, complete the remaining

portion of this procedure to determine whether still lower

oxygen levels are practical.

3. Increase combustion air flow to the furnace until stack

gas oxygen levels increase by one to two percent over the

level measured in Step 2. As in Step 2, record the stack

gas temperature, CO concentration (for gaseous fuels) or

smoke-spot number (for liquid fuels), and observe flame

conditions for these higher oxygen levels after boiler

operation stabilizes.

4. Decrease combustion air flow until the stack gas oxygen

concentration is at the level measured in Step 2. From this

level gradually reduce the combustion air flow, in small

increments. After each increment, record the stack gas

temperature, oxygen concentration, CO concentration (for

gaseous fuels) and smoke-spot number (for liquid fuels).

Also observe the flame and record any changes in its

condition.



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1. This tuning procedure is based on a tune-up procedure

developed by KVD, Inc. for the EPA.

2. The smoke-spot number can be determined with ASTM Test

Method D-2156 or with the Bacharach method.

3. Typical minimum oxygen levels for boilers at high firing

rates are:

1. For natural gas:0.5% - 3%

2. For liquid fuels:2% - 4%

4. Decrease combustion air flow until the stack gas oxygen

concentration is at the level measured in Step 2. From

this level gradually reduce the combustion air flow, in

small increments. After each increment, record the stack

gas temperature, oxygen concentration, CO concentration

(for gaseous fuels) and smoke-spot number (for liquid fuels).

Also observe the flame and record any changes in its

condition.

5. Continue to reduce combustion air flow stepwise, until one

of these limits in reached:

a. Unacceptable flame conditions - such as flame

impingement on furnace walls or burner parts, excessive

flame carryover, or flame instability.

b. Stack gas CO concentrations greater than 400 ppm.

c. Smoking at the stack.

d. Equipment-related limitations - such as low windbox /

furnace pressure differential, built in air-flow

limits, etc.

6. Develop an 02/CO curve (for gaseous fuels) or 02/smoke

curve (for liquid fuels) similar to those shown in Figures 1

and 2 using the excess oxygen and CO or smoke-spot number data

obtained at each combustion air flow setting.

7. From the curves prepared in Step 6, find the stack gas

oxygen levels where the CO emissions or smoke-spot number

equal the following values:

Fuel Measurement Value

Gaseous CO Emissions 400 ppm

#1 & #2 oils smoke-spot number number 1

#4 oil smoke-spot number number 2

#5 oil smoke-spot number number 3

Other oils smoke-spot number number 4

The above conditions are referred to as CO or smoke

threshold, or as the minimum excess oxygen level.

Compare this minimum value of excess oxygen to the expected

value provided by the combustion unit manufacturer. If the

minimum level found is substantially higher than the value

provided by the combustion unit manufacturer, burner

adjustments can probably be made to improve fuel and air

mixing, thereby allowing operation with less air.

8. Add 0.5 to 2.0 percent to the minimum excess oxygen level

found in Step 7 and reset burner controls to operate

automatically at this higher stack gas oxygen level. This

margin above the minimum oxygen level accounts for fuel

variations, variations in atmospheric conditions, load

changes, and nonrepeatability or play in automatic controls.

9. If the load of the combustion unit varies significantly

during normal operation, repeat Steps 1-8 for firing rates

that represent the upper and lower limits of the range of

the load. Because control adjustments at one firing rate

may affect conditions at other firing rates, it may not be

possible to establish the optimum excess oxygen level at all

firing rates. If this is the case, choose the burner

control settings that give best performance over the range

of firing rates. If one firing rate predominates, settings

should optimize conditions at that rate.

10. Verify that the new settings can accommodate the sudden

load changes that may occur in daily operation without

adverse effects. Do this by increasing and decreasing load

rapidly while observing the flame and stack. If any of the

conditions in Step 5 result, reset the combustion controls

to provide a slightly higher level of excess oxygen at the

affected firing rates. Next, verify these new settings in a

similar fashion. Then make sure that the final control

settings are recorded at steady-state operating conditions.