TO:	EPA Docket No. EPA-HQ-OAR-2003-0146

		

FROM:	Bob Lucas, EPA/SPPD 

DATE:	August 17, 2007

SUBJECT:	Miscellaneous Process Vents:  Control Options and Impact
Estimates 

I.	Purpose

This memorandum documents the methodology used to identify the control
options and estimate the costs and environmental impacts for
miscellaneous process vents control options. 

II.	Background

Section 112 (f) of the Clean Air Act Amendments (CAA) directs the U.S.
Environmental Protection Agency (EPA) to assess source categories
regulated under Section 112(d) of the CAA and determine whether any
human health or environmental risks remain from the continued emissions
of hazardous air pollutants (HAPs) following implementation of maximum
achievable control technology (MACT) standards.  The CAA further states
that if the MACT standards do not reduce lifetime excess cancer risk to
the most exposed individual to less than one in one million, EPA must
set additional standards to protect human health and the environment, in
accordance with the interpretation set forth in the Benzene NESHAP. 
Additionally, the EPA is required to review these technology-based
standards and to revise them “as necessary (taking into account
developments in practices, processes and control technologies)” no
less frequently than every 8 years, under CAA section 112(d)(6).  The
Refinery MACT 1 (40 CFR Part 63 Subpart CC) was promulgated over 8 years
ago and is now being reviewed.   

III.	Summary of Existing Refinery MACT 1 Miscellaneous Process Vents
Control Requirements

Refinery MACT 1 requires Group 1 miscellaneous process vents to control
emissions of organic HAP.  Refinery MACT 1 defines miscellaneous process
vents as:

gas streams containing greater than 20 parts per million by volume
organic HAP that is continuously or periodically discharged during
normal operation of a petroleum refining process unit. Miscellaneous
process vents include gas streams that are discharged directly to the
atmosphere, gas streams that are routed to a control device prior to
discharge to the atmosphere, or gas streams that are diverted through a
product recovery device prior to control or discharge to the atmosphere.
Miscellaneous process vents include vent streams from: caustic wash
accumulators, distillation tower condensers/accumulators, flash/knockout
drums, reactor vessels, scrubber overheads, stripper overheads, vacuum
(steam) ejectors, wash tower overheads, water wash accumulators,
blowdown condensers/accumulators, and delayed coker vents. Miscellaneous
process vents do not include: (1) Gaseous streams routed to a fuel gas
system; (2) Relief valve discharges; (3) Leaks from equipment regulated
under §63.648; (4) Episodic or nonroutine releases such as those
associated with startup, shutdown, malfunction, maintenance,
depressuring, and catalyst transfer operations; (5) In situ sampling
systems (onstream analyzers); (6) Catalytic cracking unit catalyst
regeneration vents; (7) Catalytic reformer regeneration vents; (8)
Sulfur plant vents; (9) Vents from control devices such as scrubbers,
boilers, incinerators, and electrostatic precipitators applied to
catalytic cracking unit catalyst regeneration vents, catalytic reformer
regeneration vents, and sulfur plant vents; (10) Vents from any
stripping operations applied to comply with the wastewater provisions of
this subpart, subpart G of this part, or 40 CFR part 61, subpart FF;
(11) Coking unit vents associated with coke drum depressuring at or
below a coke drum outlet pressure of 15 pounds per square inch gauge,
deheading, draining, or decoking (coke cutting) or pressure testing
after decoking; (12) Vents from storage vessels; (13) Emissions from
wastewater collection and conveyance systems including, but not limited
to, wastewater drains, sewer vents, and sump drains; and (14) Hydrogen
production plant vents through which carbon dioxide is removed from
process streams or through which steam condensate produced or treated
within the hydrogen plant is degassed or deaerated.

Refinery MACT 1 defines Group 1 miscellaneous process vents as: 

miscellaneous process vents for which the total organic HAP
concentration is greater than or equal to 20 parts per million by
volume, and the total volatile organic compound emissions are greater
than or equal to 33 kilograms per day for existing sources and 6.8
kilograms per day for new sources at the outlet of the final recovery
device (if any) and prior to any control device and prior to discharge
to the atmosphere.

Refinery MACT 1 requires Group 1 miscellaneous process vents to control
emissions of organic HAP by using a flare, or to reduce emissions of
organic HAP by 98 weight-percent or to a concentration of 20 parts per
million by volume, on a dry basis, corrected to 3 percent oxygen through
the use of a control device, whichever is less stringent.

IV.	Identification of Control Options

Two options were identified for protecting human health and the
environment through the control of miscellaneous process vents.  The
options involve lower cut-offs for total organic HAP.

Option 1:  set a limit of 25 lb/day of organic HAP for each
miscellaneous process vent.

Option 2:  set a limit of 15 lb/day of organic HAP for each
miscellaneous process vent.

Based on the typical stream compositions obtained during the development
of Refinery MACT 1 (Lucas, 2007), the gas phase composition for most
refinery process streams typically contains only about 10 percent HAP. 
There are, however, some liquid process streams that contain 50 percent
or more HAP.  Therefore, most gaseous miscellaneous process vent streams
are expected to exceed the 33 kg/day (72 lb/day) total VOC well before
they exceed the total organic HAP emission thresholds evaluated in these
options.   That is, these control options would only impact a very small
percentage of Group 2 miscellaneous process vents; and any vents that
are impacted would have to have significant (50 to 100 percent) HAP
content.  For the purposes of this analysis, it was assumed that these
selected miscellaneous process vents are 100 percent HAP, so that the
VOC reduction estimate is the same as the organic HAP emission
reductions.  

To evaluate the two control options, two “model vents” were
developed.  The first model vent was assumed to have organic HAP
emission rate of 40 lb/day (to represent vents between the 25 lb/day
threshold in Option 1 and the 72 lb/day threshold in the existing
Refinery MACT 1 rule).  The second model vent was assumed to have
organic HAP emission rate of 20 lb/day (to represent vents between the
25 and 15 lb/day thresholds in Options 1 and 2). 

V.	Impact Estimates

Control Costs 

All refineries will have to evaluate their Group 2 miscellaneous process
vents to determine the number of miscellaneous process vents that may
HAP emissions significant enough to potentially trigger the total
organic HAP threshold.  If needed, vent stream samples would need to be
collected to augment or confirm engineering calculations.  The analysis
would need to be summarized and reported to demonstrate compliance with
the rule requirements or notify the need to control the vent stream.  We
assumed that 150 refineries would have at least one Group 2
miscellaneous process vent and need to undertake these activities.  On
average, we estimated that 8 technical hours would be needed per
refinery.  For each technical hour, we assumed 0.05 management hours and
0.1 administrative hours were also required.  Table 1 provides the
basis of the loaded labor rates used for this analysis.  Eight technical
hours, therefore, represents a cost of $1,010, fully burdened.  

We also assumed each refinery would take a grab gas sample for analysis
to confirm the vent stream HAP composition on one vent stream.  The
total cost of canister rental and a full-speciation panel chemical
analysis at the contract testing laboratory the chemical analysis was
estimated to be $435.  Therefore, we estimate that 150 refineries would
each incur an initial cost of $1,445 to determine whether or not they
have a miscellaneous process vent that is subject to control under the
new threshold options, resulting in a nationwide one-time cost of
approximately $217,000.  Averaging these costs over 5 years results in a
nationwide annual cost of $43,400/yr

Refineries that have Group 2 miscellaneous process vents exceeding the
control option thresholds would have to either send the gases to the
fuel system or connect the vent gases to a flare or control device
achieving 98 percent control efficiency.  As discussed previously, only
a small fraction of miscellaneous process vents would are expected to
have HAP concentrations significant enough to be affected by these
control options.  Nonetheless, capital control costs for those vents
impacted under Options 1 or 2 were estimated using the costs reported in
the vent stream cost analysis for the Synthetic Organic Chemical
Manufacturing Industry (SOCMI) (EPA, 1992).  We assumed that process
vent emissions could be controlled by an existing flare or process
heater so the only capital costs are those of piping from the vent to
the flare (or other control device) and the addition of a knock-out drum
to eliminate mist entrainment.  The SOCMI analysis assumed 300 feet of
piping with a diameter of 1 inch, resulting in a purchased equipment
cost of $381 for piping.  The knock-out drum in the SOCMI analysis was
18 inches in height, 6 inches in diameter, and ¼ inches thick, and had
a purchased equipment cost of $193.  These cost estimates were developed
in 1992, so the costs were escalated to 2006 dollars using the average
CEPCI in 1992 of 358.2 and the average CEPCI in 2006 of 499.6. 
Therefore, the purchased equipment cost of controlling a single process
vent was estimated to be $800 [($381+$193)×499.6/358.2].  

Table 1.  Summary of 2006 Labor Rates

Labor Class	(A)

Labor Rate from the Bureau of Labor Statistics	(B)

Fringe Benefit Loading rate from BLS	(C)

Overhead and profit rate from MWC ICR	(D)

Loaded wage rate 

(A x B x C)

1. Professional specialty and Technical	48.27	1.43	1.67	115.27

2. Executive, administrative and managerial	59.15	1.40	1.67	138.29

3. Administrative support, including clerical	17.46	1.41	1.67	41.11

4. Installation, Maintenance, and Repair	24.28	1.40	1.67	56.77

5. Plant and System Operators, All	20.64	1.40	1.67	48.26

May 2006 Labor rates (accessed in Jun 2007).

http://stats.bls.gov/home.htm

http://stats.bls.gov/oes/current/oessrci.htm	total cost/tech hr*	126.30

	*Calculated as: D1+ 0.05D2 + 0.1D3

Where D1, D2, and D3 are cell references above.



This $800 represents only the purchased equipment costs; installed costs
are typically estimated as approximately 2 times the purchased equipment
costs.  However, for these low purchased equipment costs, this approach
is expected to seriously understate the actual installation costs. 
Before the equipment can be purchased, an engineer would need to
evaluate the control options (identify the nearest flare header or
process heaters, evaluate the technical feasibility of using each
potential tie-in location, etc.), select the best option, plan the
piping and tie-in locations, and develop the purchase specifications. 
We assumed this would require 40 technical hours (plus associated
management and administrative hours).  Once the equipment was purchased,
we estimated 20 installation/maintenance/repair labor hours would be
needed to install the piping and knock-out drum.  Therefore, the total
installed cost of the controls was estimated to be $7,000 ($800 +
40×$126.3 + 20×$56.77).  These costs were considered capital
investments and were annualized over 10 years assuming a 7 percent
interest rate, resulting in an annualized cost of capital of $990 for
each vent that needed additional control.  On-going costs were assumed
to be minimal.  One operating hour was assumed per week to inspect the
line for pluggage and/or leaks; we assumed that one “repair”
requiring 8 hours of maintenance labor per year, resulting in operating
and maintenance costs of approximately $3,830 per year per controlled
vent.

Because this analysis assumed that it is technically feasible to tie-in
to an existing control, the costs estimated here are expected to
represent the lowest plausible cost.  Actual control costs may
significantly exceed these costs. 

Emission Reductions

The controls must achieve 98 percent emissions reduction.  For
miscellaneous process vents represented by the first model vent, a 98
percent reduction equates to total HAP emissions reduction of 39.2
lb/day.   For miscellaneous process vents represented by second model
vent, a 98 percent equates to total HAP emissions reduction of 19.6
lb/day.  No data were available on the number of Group 2 miscellaneous
process vents that are present at a typical refinery.   As in
development of the cost estimates, we assumed that there are 150
refineries that contain at least one Group 2 miscellaneous process vent.
 However, only a small fraction of these vents will contain HAP in
concentrations high enough to trigger controls under Options 1 or 2.  

Of the 150 Group 2 miscellaneous process vents that needed to be
specifically evaluated, we assumed that 4 percent (i.e., 6 vents) would
exceed the 25 lb/day (i.e., represented by Model Vent 1) and an
additional 4 percent (6 vents) would exceed the 15 lb/day threshold. 
Under Option 1, the 6 affected miscellaneous process vents would each
reduce emissions by 39.2 lb/day on average.  Assuming 365 days per year
operation, the annual emission reductions would be 42.9 tons per year
(tpy) [(39.2 lb/day/vent × 6 vents × 365 days/yr) / 2000 lbs/ton]. 
Under Option 2, you would get all of the emission reductions under
Option 1 plus an additional 21.5 tpy.  These emission reductions are
likely to over estimate the total annual emission reductions because
these miscellaneous process vents do not always operate continuously.

Nationwide Impacts

The nationwide impact estimates for miscellaneous process vents are
shown in Table 2.  This analysis is based on assuming 6 vents require
controls under Option 1 and an additional 6 vents require controls under
Option 2.  As discussed previously, the cost estimates assume that the
vents can be tied to a nearby existing control device or flare header. 
Additionally, the emission estimates are likely overstated because they
assume continuous vent operation and they assume that the emissions are
100 percent HAP.  As such, the cost-effectiveness values presented in
Table 2 likely biased low.  The actual cost per ton of HAP removed may
be significantly higher if an additional control device is needed and/or
the vent stream operates only intermittently or has less than 100
percent HAP. 

Table 2.  Nationwide Impacts of Refinery Miscellaneous Process Vent
Control Options

Control Option 

	Total Capital Investment  ($)	Average Initial Evaluation Costs

($/yr)	Annual Operating Costs of Controls ($/yr)	Total Annualized Costs
($/yr)	HAP Emission Reduction from Baseline

(tpy)	Cost-Effectiveness

($/ton HAP)

1.  >25 lb/day HAP	42,000	216,800	23,000	245,700	42.9	5,700

2.  >15 lb/day HAP	84,000	216,800	46,000	274,700	64.4	4,300



VI.	References

Lucas, B.  2007.  Memorandum from B. Lucas, EPA/SPPD, to Project Docket
File (EPA Docket No. EPA-HQ-OAR-2003-0146).  Average Refinery Stream
Composition.  August 6, 2007.

U.S. EPA (Environmental Protection Agency).   1992.  Hazardous Air
Pollutant Emissions from Process Units in the Synthetic Organic Chemical
Manufacturing Industry--Background Information for Proposed Standards;
Volume 1B:  Control Technologies.  Document Number EPA-453/D-92-016b. 
November.

Technical Memorandum – Miscellaneous Process Vents:  Control Options
and Impact Estimates

August 17, 2007

Page   PAGE  6 

Technical Memorandum

