Fuel combustion emissions

Uncontrolled emissions are not calculated. NMVOC emission was calculated by Simsir S [49] in 2010 as 3,250 ton/yr, however in this study NMVOC emissions were calculated within VOC emissions as 26,903 ton/yr.

5.2.3. Fuel combustion emissions

The fuel combusted within petroleum refineries to produce the heat and steam needed to run the refinery processes typically amounts to 6 to 10 percent of the total fuel input to the refinery, depending on the complexity and vintage of the technology [32].

Fuel combustion data was taken from the General Energy Balance Table (2010) of Ministry of Energy and Natural Resources (MENR) [8]. Petroleum refineries consumed electricity, petrol and natural gas for the usage in the processes and residential purposes in the refinery in 2010.

5.2.3.1. Natural gas combustion

Natural gas utilization was taken from MENR 2010 general energy balance table for petroleum refineries as 1,103,000,000 Sm³.

First of all combustor type was decided with using hourly heat input data which was derived from MENR tables’ [46] data with considering the number of the boilers for each of the refineries. Finally, combustor type was found as large wall fired which has more than 100 MMBtu heat input per hour.

PM Emission factor was selected from EMEP [40] as 0.89 g/GJ. It was 4 g/GJ in AP42 [39] as the sum of filterable and condensable PM. This pollutant was not calculated in NIR 2010.

SO2 emission factor was selected from EMEP [40] as 0.3 g/GJ; however it was 0.278 g/GJ in AP42 [39] with considering 100% conversion of sulphur to SO₂.

CO emission factor was given same in both of AP42 [39] and EMEP [40] as 39 g/GJ.

NO_x emission factor was chosen from AP42 [39] for uncontrolled post NSPS conditions as 88 g/GJ; however it was recommended 60 g/GJ in EMEP.

CO2 emission factor was selected from IPCC- Tier 1 as 56,100 g/GJ.

N2O emission factor was taken from AP42 [39] for uncontrolled conditions as 0,3 g/GJ. There is no recommendation in EMEP [40]. It was taken in NIR 2010 as 2.2 g/GJ.

NMVOC emission factor was selected as 2.6 from EMEP [40]. There was no recommendation for NMVOC in EMEP [40], however NMVOC parameter was calculated in some of the studies and also NIR 2010, therefore it was calculated here.

All of these emission factors were summarized in Table 5.29. Also these results were compared with former studies in Table 5.31.

5.2.3.2. Fuel oil combustion

Two major categories of fuel oil are burned by combustion sources: distillate oils and residual oils; with Nos. 1 and 2 being distillate oils; Nos. 5 and 6 being residual oils;

and No. 4 being either distillate oil or a mixture of distillate and residual oils which are produced from the residue remaining after the lighter fractions (gasoline, kerosene, and distillate oils) have been removed from the crude oil, they contain significant quantities of ash, nitrogen, and sulphur.

Table 5.29 : Unabated natural gas combustion emissions for petroleum refineries.

Pollutant EF

Residual oils are used mainly in utility, industrial, and large commercial applications [50]. No 6 Oil was assumed to be used in refinery for combustion however in NIR Turkey 2010 refinery gas was assumed to be used in refineries [26].

Emission factors used in calculations and final emissions for refinery fuel oil combustion were given in Table 5.30. Fuel oil consumption of oil refineries was 925,000 ton [8] in 2010.

Table 5.30 : Fuel oil combustion emissions of petroleum refineries.

Pollutant EF

PM emission factor was chosen from EMEP [40] as 20 g/GJ. However it was given by EPA [50] as approximately 385 g/GJ for filterable PM (particulate collected on or prior to the filter of an EPA Method 5 or equivalent sampling train and calculated by Sulphur content of the fuel) and approximately 4.3 for condensable emissions. To reach more realistic results, and for the information deficit about the specific filter of EPA Method 5, EMEP emission factor was used.

SO₂ emission factor 485 g/GJ in EMEP [40] and considers SO₂ abatement and is based on 1% mass sulphur content. There was no information about SO₂ abatement, therefore SO₂ emission factor was chosen from EPA [50] as 630.53 g/GJ. Average weight percentage of the sulphur in the oil is 1.4% as announced by Tupras [42].

This value was directly used for calculations.

NO_x emission factor is given as 125 g/GJ in EMEP [40] but it was taken from EPA [50] as 194 g/GJ which was expressed as NO2. Fuel nitrogen conversion is the more important NOx -forming mechanism in residual oil boilers. It can account for 50 percent of the total NOx emissions from residual oil firing. The percent conversion of fuel nitrogen to NOx varies greatly, however; typically from 20 to 90 percent of

nitrogen in oil is converted to NO_x. Except in certain large units having unusually high peak flame temperatures, or in units firing a low nitrogen content residual oil, fuel NOx generally accounts for over 50 percent of the total NOx generated. [50].

NOx emission = (20,54 + 104,39xN)*0,12 (5.2) NO_x emission factor was calculated with the Equation 5.2 which was taken from AP42 [50].

NO_x emission: calculated as 5.64 kg NO_x /m³

N: weight percentage of Nitrogen in the fuel (0.45 [51])

CO2 emission factor was given as 73,300 g/GJ in IPCC Guideline Tier 1 Method [32]

and 72,600 g/GJ value was used in NIR Turkey 2010 [26]. This value was directly related with the carbon content of the fuel combusted. No 6 fuel oil was accepted to be used in oil refineries and specific emission factor of this fuel was given in EPA [50] as 71,716 g/GJ. However, this value is not certain for Turkish refineries’ fuel oils and can be updated with the certain information about carbon content of the fuel used in refineries.

N2O emission factor was taken from EPA [50] as 1,52 g/GJ, however it was given as 6 g/GJ in IPCC Guideline [32] and same value was used in NIR Turkey 2010 [26].

Formation of N2O is minimized when combustion temperatures are kept high (above 801.67 °C) and excess air is kept to a minimum (less than 1 percent). Emissions can vary widely from unit to unit, or even from the same unit at different operating conditions. Average emission factors based on reported test data have been developed for conventional oil combustion systems [50]. NO_x emission factor of EPA [50] was high when compared to other sources. Therefore N₂O emission factor was chosen from AP42 too, despite of being lower when compared to other sources with considering internal conversions between NO_x could be considered in emission factor determining by EPA.

CH4 emission factor was taken from IPCC Guideline [32] as 3 g/GJ, it was given by EPA [50] as 2.87 g/GJ.

NMVOC emission factor of EPA [50] interacted with VOC emissions under Total Organic Carbons title and there is no clear distinction between these parameters.