Bureau of Energy Efficiency has issued PAT-2 notification in which “Refinery” has been added as a new sector. Total 18 refineries feature in this list with their baseline and target energy performance data. In all other sectors, specific energy consumption (SEC) is measured in terms of product (output) quantity and total annual energy consumption. However the same methodology is difficult to be adopted here because of numerous products or outputs of a refinery. In case of refinery, the quantity of crude oil (generally expressed in barrels) processed by them (also termed as refinery throughput) is being considered for SEC calculation. As mentioned here a refinery can produce different grades of products depending upon the type of finishing and conversion units which follow the basic separation units (mainly ADU & VDU). Therefore energy requirement to process one barrel of crude of any refinery will vary widely based on the conversion process (apart from crude quality). There is a misconception among most of the EnMS auditors that distillation process (atmospheric & vacuum distillation) in any refinery consumes the maximum amount of energy. However in reality this is not the case. Given below the energy consumption breakup of various sub-processes of a refinery-
To address this issue, refineries across the world follow “Solomon Energy Intensity Index” (EII) benchmark system which defines the complexity of any refining process. Following this international guideline, BEE has developed its indigenous Energy Performance Index which links SEC with the complexity/ criticality of any refinery and it is called – MBN (Million British Thermal Unit per Thousand barrels per Energy Factor). Complexity of the refinery is expressed as NRGF and the composite NRGF of the plant is calculated considering the individual energy factor and throughput of each sub-process.
Before looking at the energy performance data of the refineries – we must know the difference between theoretical and practical SEC of oil refining process. Theoretical energy is the amount of energy which is required to complete a chemical reaction or unit operation under ideal conditions with no loss of energy/ heat to the surroundings. The practical energy on the other hand is the amount of energy that is consumed during a reaction or unit operation under real conditions by any standard equipment. Therefore maximum possible energy reduction for any refinery is the “GAP” between these two values. The lowest possible SEC which has been achieved by using latest generation technology and best operational practices is termed as “Benchmark SEC”. It is judicious to measure the performance of any refinery by comparing its SEC with the world benchmark value.
The world benchmark SEC value of refinery varies from 523 Kcal to 872 Kcal per liter of crude depending upon the complexity of the refining process. In other words, self consumption of crude is 5.23% to 8.72% during its processing. To make it lucid we can say that – if a simple refinery doesn’t purchase any energy from outside (beyond its boundary) then it can process 1 barrel of crude (159 liter) by burning 8.32 liters as captive consumption.
Now let us look at the energy performance data of Indian refineries notified under PAT scheme. We see very wide range for parameters like “Throughput”, “NRGF”, “MBN” and “SEC”.
- Throughput: It varies from 2.81 to 41.44 MMTPA (Million Metric Ton per annum) with an average figure of 14.08 MMTPA per refinery.
- Composite NRGF: Range is 4.2178 to 10.259. Hence we can segregate the refineries in three category based on NRGF values- Simple (NRGF ? 5), Complex (5 ≤ NRGF ? 9) and Highly Complex (NRGF ≥ 9). Based on this classification there are 5, 10 and 3 numbers of units in simple, complex and highly complex category respectively.
- MBN: Varies from 50.9986 (Highly Efficient) to 99.895 (Less Efficient).
- SEC: It varies from 523.82 to 1042.13 Kcal/liter with an average SEC of 731.25 Kcal/ liter.
The graphical representations of the above factors are given for the refinery sector-
NRGF Vs. MBN:
MBN Vs. SEC:
MBN Vs. % Reduction Target:
From the above we see that Indian refineries are operating very close the global benchmark SEC or MBN. Specific Energy reduction target for the refineries under PAT Cycle-2 varies from 4.39% to 8.60% with an average reduction target of 6.60% for the whole sector. Since most of the refineries are operating near the benchmark value- it will be very challenging for them to achieve their individual targets. Under this ambitious plan, the total energy saving targeted from this sector alone is 11.03 million metric ton of oil which is almost double of the national target under PAT Cycle-1 (6.686 MMTOE/ year). However refineries should plan to work in this direction from beginning of the cycle. Since more than 40% of the operating cost of any refinery attributes to energy cost - it will help them to improve the refining margin in the long run and become competitive in the global market for the finished products.
N.B- All values above have been calculated considering specific gravity of crude as 1 and GCV of crude as 10,000 Kcal/liter.
Bureau of Energy