Microsoft Word master thesis report fina doc

Part A: Major emission sources of refineries and 
petrochemical industry 
1. Fugitive emissions 
1,2,3,4 
Equipment leaks in refinery processes are responsible for significant amount of emissions. 
Even if each individual leak is generally small, according to EPA, it is the largest source of 
emissions of volatile organic compounds (VOCs) and volatile hazardous air pollutants 
(VHAPs) from petroleum refineries and chemical manufacturing facilities. The US EPA 
(United States Environmental Protection Agency) emitted in 1995 a protocol for equipment 
leak emission estimates based on emission factors or correlation approaches. The emission 
factors approach is the only method available that allows estimation without monitoring. This 
method is described below. The implementation of an LDAR (Leak Detection And Repair) 
programme will then be dealt with. 
1.1. Average Emission Factor Approach 
The Average Emission Factor Approach is a combination of average emission factors and 
unit-specific data: number of each type of equipment (valves, pump seals, etc.), the service 
each equipment is in (gas, light liquid, heavy liquid), the Total Organic Compound (TOC) 
concentration of the stream and time period each equipment is in that service. The emission 
rate of TOC from all equipment can be calculated with the following formula: 
E
TOC
= F
A
× WF
TOC
× N 
Where: 
E
TOC
= emission rate of TOC from all equipments in the stream of a given equipment type 
(kg/hr) 
F
A
= applicable average emission factor for the equipment type (kg/hr/source) 
WF
TOC
= average weight fraction of TOC in the stream 
N = number of pieces of equipment of the applicable equipment type in the stream 
Average emission factors are divided into four categories: SOCMI factors, oil and gas 
production factors, refinery factors, and factors for petroleum marketing terminals (this last 
category is not applicable here). Within each category, factors depend on equipment type and 
material in service (light or heavy liquid or gas).Heavy liquid factor is used if the stream's 
vapor pressure is less than or equal to 0.003 bars at 20°C. If the vapor pressure is greater than 
0.003 bars at 20°C, light liquid factor must be used. 
Appendix 1 gathers all the Average Emission Factors and Appendix 2 shows an example of 
calculation. 
Total TOC fugitive emission from a unit process can be known by summing emissions from 
each type of components, from each stream. 
Average factors generally determine total hydrocarbon emissions. In order to determine total 
VOC emissions, the calculated emission rates must be multiplied by the stream’s weight 
percentage of VOC compounds. (Indeed, it can happen that not all organic compounds 
present in the stream be classified as VOCs, for instance methane or ethane. 

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2
If some of the organic compounds in the stream are not classified as VOCs total VOCs 
emission can be calculated with the following formula: 
E
VOC
= E
TOC
× (WP
VOC 
/ WP
TOC
) 
Where: 
E
VOC
= the VOC mass emissions from the equipment (kg/hr) 
E
TOC
= the TOC mass emissions from the equipment (kg/hr)
WP
VOC
= the VOC concentration in the equipment in weight percent 
WP
TOC
= the TOC concentration in the equipment in weight percent 
If, for a stream, estimating emissions of a specific VOC in the mixture is necessary, the 
following formula can be used:
E
X
= E
TOC
× (WP
X 
/ WP
TOC
) 
Where: 
E
X
= the organic chemical “X” mass emissions from the equipment (kg/hr) 
E
TOC
= the TOC mass emissions from the equipment (kg/hr)
WP
X
= the organic chemical “X” concentration in the equipment in weight percent 
WP
TOC
= the TOC concentration in the equipment in weight percent 
Three other methods emitted from the protocol for equipment leak emission estimates are 
available. However these methods necessitate on-site monitoring so they are not included into 
the scope of this study. 
1.2. Implementation of a Leak Detection and Repair (LDAR) program 
Still according to EPA, the implementation of an LDAR program could lead to a reduction by 
63% of emissions from equipment leaks. The following describes the procedure to implement 
this program.