1、Short-term Evaporative Loss Estimation from Atmospheric Storage TanksAPI TECHNICAL REPORT 2576 FIRST EDITION, JULY 2016Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be re
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13、may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be
14、 submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normati
15、ve References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Estimating Reasonable Worst-case Short-term Emissions from an Individual Storage Tank. . . . . . . . . . 13.1 Liquid Storage Temperature . . . . .
16、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Product Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.3 Fixed-roof T
17、anks (Vented to Atmosphere, No Floating Roof) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.4 Floating-roof Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Estimating Rea
18、sonable Worst-case Short-term Emissions from a Battery of Storage Tanks. . . . . . . . . . 54.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.2 Overlaying Equipment Limitations
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Annex A (informative) Limitations on Applicability to Actual Short-term Emission Estimates . . . . . . . . . . . . . 7vIntroductionThis Technical Report provides guidance on how to de
20、termine reasonable worst-case short-term hourly emissions from individual tanks and from a battery of tanks.Currently available estimation methodologies are based on factors that rely on averaging throughputs and meteorological conditions on a yearly or monthly frequency and may deviate significantl
21、y when compared to a reasonable worst-case short-term duration of hours to days. This guidance document presents a standardized approach for estimating reasonable worst-case short-term emissions, but it does not address estimation of actual short-term emissions (see Annex A for limitations on applyi
22、ng this methodology to actual scenarios). This short-term approach combined with the dispersion model will provide the user the ability to assess potential higher mass scenarios relative to yearly averages and can be used for process safety assessments, structure siting, area classifications, determ
23、ining the need for additional controls, assessing risk of potentially elevated hazardous air pollutants (HAPs) from a confluence of conditions, and other possible concerns associated with short-term scenarios such as approach to lower explosive limit (LEL) or odor potential. Hourly and annual emissi
24、ons are used in air dispersion models that evaluate a facilitys risk against the National Ambient Air Quality Standards for the purpose of issuing construction and operating air permits. Hourly emission rates are also used to evaluate whether or not there has been an emission increase to determine i
25、f a tank has been “modified” and has become subject to a New Source Performance Standard (NSPS) or a New Source Review (NSR). EPAs 2011 Refinery MACT Information Collection Request (ICR) Protocol required reporting “maximum hourly average emission rates” based on “the reasonable worst-case (high emi
26、ssion rate) situation,” but did not provide a methodology. vi1Short-term Evaporative Loss Estimation from Atmospheric Storage Tanks1 ScopeThis Technical Report provides methodology on how to estimate short-term individual tank and facility-wide emissions. The methodology is intended to generate reas
27、onable worst-case short-term emission estimates, and not necessarily an estimate of actual short-term emissions (see Annex A for limitations on applying this methodology to actual scenarios). The methodology is applicable to routine tank operations and not applicable to emissions associated with mai
28、ntenance activities or tank roof landings. The methodology is applicable for estimating short-term emissions from tanks with fittings and seals in good condition and not applicable for tanks with damaged seals or roof fittings. Also, this methodology is not intended for situations where a tank has a
29、 malfunction, the emission controls are not working as intended, or there is other structural damage.The calculated mass emissions using this methodology can be used as input for short-term air dispersion modeling. The Technical Report does not provide guidance on applicability of any particular air
30、 dispersion models or modeling protocol.2 Normative ReferencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendmen
31、ts) applies.API Manual of Petroleum Measurement Standards (MPMS) Chapter 19.1, Evaporative Loss from Fixed-Roof Tanks, 4th Edition, 2012.API MPMS Chapter 19.2, Evaporative Loss from Floating-Roof Tanks, 3rd Edition, 2012.API MPMS Chapter 19.4, Evaporative Loss Reference Information and Speciation Me
32、thodology, 3rd Edition, 2012.3 Estimating Reasonable Worst-case Short-term Emissions from an Individual Storage TankNOTE While units from these calculations are typically in pounds/year from the referenced API MPMS Ch. 19.1 and 19.2 standards, the short-term emissions durations are usually calculate
33、d on the order of hours to days. See Annex A for a more complete explanation of limitations. 3.1 Liquid Storage TemperatureLiquid surface temperature is correlated to tank short-term emissions. If the tank is not fully insulated, then the average daily liquid surface temperature for a given time per
34、iod is determined as a weighted average of the ambient and liquid bulk temperatures. TLA= 0.4TAA+ 0.6TB+ 0.005I 1This expression for average daily liquid surface temperature may be converted to a reasonable worst-case maximum liquid surface temperature by using the average daily maximum ambient temp
35、erature, TMAX, for the month in 1API MPMS Ch. 19.1, 4th Edition, 2012, Equation 8, and API MPMS Ch. 19.2, 3rd Edition, 2012, Equation 14; average daily liquid surface temperature (TLA).SHORT-TERM EVAPORATIVE LOSS ESTIMATION FROM ATMOSPHERIC STORAGE TANKS 2question, rather than the average daily ambi
36、ent temperature, TAA. This is for the default condition of Hs/D, equal to 0.5.The expression then becomesTLX= 0.4TMAX+ 0.6TB + 0.005I 2whereTLXis the average daily maximum liquid surface temperature,TMAXis the average daily maximum ambient temperature (R),TBis the average liquid bulk temperature (R)
37、, is the tank surface solar absorptance (dimensionless), andI is the average daily total insolation on a horizontal surface (Btu/(ft2day).The variables should be evaluated as follows.TMAXis determined from ambient temperature data for the month identified for each tank type below.TBis the average li
38、quid bulk temperature for the month identified for each tank type below, which may be determined from actual measurements or process knowledge. In the event that the average liquid bulk temperature is not known, it may be estimated for tanks that are in nominal equilibrium with ambient conditions (s
39、ee API MPMS Ch. 19.1, 4th Edition, Equation (12) or API MPMS Ch. 19.2, 3rd Edition, Equation (18). is determined from the tank color and surface condition (see API MPMS Ch. 19.4, 3rd Edition, Section 4.8).I is the average daily total insolation on a horizontal surface for the month identified for ea
40、ch tank type below (see API MPMS Ch. 19.4, 3rd Edition, Table 1).Refer to API MPMS Ch. 19.1 for guidance on calculating the liquid surface temperature in an insulated tank. 3.2 Product StorageThe chemical properties of the product stored in the tanks are the primary parameters used to estimate emiss
41、ions from a tank. For tanks that can store multiple products throughout the year, emissions should be calculated for each product. In some states, it is accepted practice to use the highest-emitting product or hazardous air pollutant (HAP) combined with a Protective Action Criteria (PAC)3threshold o
42、r Effects Screening Level (ESL)4to be representative of worst-case hourly emissions. As an example, for the same tank configuration, same throughput, same location, and same season, gasoline with a Reid Vapor Pressure (RVP) of 12 psi will most often represent a worst case relative to gasoline stored
43、 with an RVP of 9 psi, assuming HAP contents are the same. If for the same scenario the HAP content of the RVP 9 psi gasoline were significantly higher than the RVP 12 psi gasoline, then the RVP 9 psi gasoline may be a worst case based on a particular HAP or chemical properties. Chemical parameters
44、obtained from actual product measurements are preferred over more generic properties representing a broadly defined class of products.2API MPMS Ch. 19.4, 3rd Edition, 2012, Section I 4.1.3US DOE Office of Emergency Management and Policy, Emergency Management Issues Special Interest Group, http:/ Com
45、mission on Environmental Quality (TCEQ), Office of Toxicology, http:/www.tceq.texas.gov/toxicology/esl/list_main.html3 API TECHNICAL REPORT 25763.3 Fixed-roof Tanks (Vented to Atmosphere, No Floating Roof)The maximum short-term emission rate, LMAX, is to be determined using the working loss, LW, whi
46、ch is calculated with the throughput based on the maximum filling rate and with the turnover (saturation) factor, KN, set equal to 1. The liquid surface temperature is to be set using the liquid surface temperature equation in 3.1. An annual working loss, LW, can then be determined from API MPMS Ch.
47、 19.1 equations. If the tank stores different stocks during the course of a year, then each stock should be evaluated separately. Given that the working loss would typically be the dominant mechanism driving short-term emission rates for fixed-roof tanks, the calculation of short-term emission rates
48、 for typically controlled fixed-roof tanks without vapor recovery may be based on only the working loss. (i.e. the standing loss may be neglected).Follow the following steps.Step 1: Use API MPMS Ch. 19.1, Section 4.3.1, Equation (21)5to calculate annual working loss, LW, with: throughput calculated
49、from the maximum filling rate, the turnover (saturation) factor, KN, set to 1.0, the product factor, Kc, for crude oil stocks is set to 1.0, and the liquid surface temperature determined from 3.1 of this document.Step 2: Divide this annual working loss by 8760 hr/yr to obtain the maximum short-term emission rate, LMAX.3.4 Floating-roof Tanks3.4.1 OverviewFor floating-roof tanks, the type of floating-roof construction, including all deck fitting data, has to be known in order to accurately estimate emissions.The short-term emission
