Refinery Overhaul Done by Iran Technicians
Imam Khomeini Oil Refining Company (IKORCO), located in Markazi Province, has been overhauled three times since the beginning of Iranian current calendar year in March; one overhaul in spring and two overhauls in autumn.
One of the most significant sections of the refinery in the overhaul process is the RCD unit which processes distillation tower residues. For the first time in Iran, residual hydrogen treatment unit with a capacity of 69,000 b/d has been designed and built with a view to reducing the sulfur content of distillation towers. This unit will prepare the necessary ground for converting heavy fuel oil to gasoline and lighter products. This unit has two sections, each of which can operate independently for treatment. Each section is incorporated with five reactors creating 385 degrees Celsius and 200 Bar pressure – which is the highest functioning pressure in refining units in the world – for the elimination of sulfur from heavy residues.
With 1,600 tonnes of catalyst, this unit is the largest hydrogen treatment unit in Iran. The main product of this unit is refined heavy residue to feed the residue fluid catalytic cracking (RFCC) unit. Diesel and naphtha are byproducts. Due to the significance of functioning of this unit, the overhaul of each section is done separately and independently.
Ali-Reza Amin, CEO of IKORCO, said: “Overhaul of ordinary units at refineries is done every three to four years, but in this unit we need overhaul every year because of heavy feedstock and quick inactivation of catalyst. Every year the catalyst is replaced.”
He said that this year’s overhaul was done in three phases. The first phase which occurred at the beginning of Iranian calendar year and lasted nearly one month was focused on five old operational units in Phase 1 of the facility. The second and third phases of overhaul were in units 12, 19 and 33 and an RCD line. This round of overhaul was done in October and November.
He said the next phase of overhaul will be for next spring.
Amin referred to the hiring of local contractors for the overhaul of the refinery, saying: “All phases of overhaul in Unit 14 RCD and Unit 19 sulfur production were handled by local contractors. We can say that 80% of staff (1,600 persons) were active from Markazi Province. Of course, specialist manpower from other parts of the country was engaged, too.”
Outlining Unit 19 (sulfur production), he said: “IKORCO has two sulfur production units. Gaseous hydrogen sulfide (obtained from amine treatment of gas) as well as the output gases of the sour water unit are feedstock for this unit where sulfur is produced by applying the Claus process.”
“The feedstock for this unit is first exposed to thermal treatment in a special furnace at over 1,100 degrees Celsius. Then, it is converted to melted sulfur in a two-phase reactor to be finally solidified and supplied on the market,” he added.
Amin said Unit No. 1 is producing 60 tonnes a day and Unit No. 2 is supplying 640 tonnes a day of sulfur with 99.5% purity in the form of granule and powder.
The refinery was launched in 1993 as the largest single-unit refining unit in Iran with a rated capacity of 150,000 b/d, which was boosted to 175,000 b/d after technical modification.
It is the first refinery in Iran, whose related studies were conducted following the 1979 Islamic Revolution amid Iraq-Iran war.
“With a view to maximizing gasoline production, reducing fuel oil output and generating value added, IKORCO teamed up with two Iranian companies – Sazeh and ODCC – and Chinese SEI to continue its work,” he said.
Amin added: “Despite all shortages and pressure due to international restrictions, thanks to God and in light of efforts by Iranian specialists this project was completed and came on-stream in February 2013.”
The startup of new units at the refinery by Iranian engineers and manpower under conditions of sanctions, in the absence of specialists and representatives of licensors, IKORCO has become the most specialized and the biggest refinery producing Euro-4 clean gasoline and gasoil by processing 250,000 b/d of crude oil.
The refinery is currently supplying such products as Euro-4 gasoline, gasoil, kerosene, light fuel oil, vacuum bottom, propylene, liquefied petroleum gas and sulfur granule.
Risk Assessment before Overhaul
During overhaul, the operational unit’s conditions are no longer normal, and therefore risks are totally different from normal conditions. Under such circumstances, different repair groups become active and each group is likely to cause risk to another one. Therefore, it would be of high significance to learn about risks and comply with safety regulations in order to prevent accidents.
Mohammad Sepehri Rad, head of maintenance at IKORKO, said: “First of all, safety courses are held for all staff who join the refinery for overhaul. Even during the process, a safety engineer is available to control safety conditions at each section. Since before overhaul, all possible risks are assessed and identified the contractors receive necessary training.”
He went on to speak about Units 12, 14 and 19, where overhaul has already been done.
“Unit 12 is a gasoline production unit whose overhaul was done this autumn. It accounts for one-fourth of gasoline production in the country. The overhaul process lasted 19 days,” he said.
Sepehri Rad said the RCD unit was overhauled in two phases, which involved Train B reactors and equipment.
Equipment and devices were repaired in 17 days, while reactors of Train B were unloaded and loaded during 28 days. Unit 19 of Train A was overhauled in 17 days.
Sepehri Rad said the RCD unit is a newly established unit in Phase 2 of IKORKO, which is tasked with treating the residue of atmospheric and vacuum residues for feedstock at RFCC. At RFCC, residual metals and sulfur are absorbed. But due to the heavy contents of the feedstock and absorption of metals and sulfur, the catalytic activity of reactors at this section decline gradually. Therefore, in order to preserve the quality of output products, new catalysts have to be incorporated.
“The overhaul in Phase 12 was over this year, and all equipment and devices, (about 202) were repaired. Furthermore, Unit 19, with 18 devices, and RCD with 34 devices were repaired. Unit 14 and Unit 19, which have two parallel trains, are repaired train-to-train in order to avoid any thorough halt in production,” said Sepehri Rad.