MRPL’s CUTTING EDGE TECHNOLOGY IN REFINING
(Mangalore Refinery and Petrochemicals Ltd. was the first refinery established outside Public Sector. First Commissioned in the year 1995, the refinery has been expanding and transforming itself. This evolution and adaptation have enabled it to face the challenges offered by the times and emerge as a vital cog in the Indian refining industry. Here is a glimpse of the cutting edge refining technologies that MRPL went to onto secure since its inception.)
Crude oil is a dark, sticky liquid, comprised of carbon and hydrogen molecules with impurities such as Sulphur, Nitrogen and metals. For using it as fuel and other value-added products, crude oil has to undergo separation and purification in a refinery.
The Refinery processes are classified into:
- Primary Processing Units – Separation Processes
- Secondary Processing Units
- Treating Units and Value Addition.
- Primary Processing Unit - Separation Processes
The first part of refining crude oil is to heat it until it boils. The boiling liquid is separated into different liquids and gases in a distillation column. During distillation, the separation takes place through relative volatility of Hydrocarbon components. Thus, distilled products have to undergo purification further for removal of impurities.
MRPL has three Crude and Vacuum distillation units totalling up to a capacity of 300,000 BPD. With the three units, MRPL has the capability to process crudes varying from 18 API to 46 API in the blend. New CDU/VDU 3, which was a part of the phase-3 expansion complex is designed to process High TAN crudes. All these units are highly integrated units which are designed to reduce energy consumption close to international benchmark.
- Secondary Processing Unit - Conversion Processes
Secondary Processing Units receive feedstock from the Crude Unit and upgrade it to value-added products. While separating the crude, there will still be many heavy hydrocarbon molecules in the streams. To convert these into lighter products, the heavy molecules are “cracked” into two or more lighter ones. The conversion process, which is carried out at close to 500°C, are categorised into three types
- Catalytic Cracking
- Hydro- Cracking
- Reforming and Isomerisation
- Thermal Cracking
a.Catalytic Cracking: The process uses a substance called a catalyst to speed up the chemical reaction. This process converts a major amount of heavy products into valuable Propylene, LPG, fuel gas, Gasoline and diesel.
Catalytic cracking in MRPL is achieved through Petroleum Fluidised Catalytic Cracker Unit (PFCCU), wherein, the feed Vacuum Gas Oil is reacted on a moving fluidised catalytic bed. MRPL PFCCU is designed to provide a high yield of Propylene, which is the raw material for valuable Polypropylene Product. In addition to Propylene, the unit generates blendstock for Gasoline.
b.Hydro-Cracking: During a catalytic cracking, the yield can be increased further by adding hydrogen, in a process called hydrocracking. In this process, the cracked products are saturated with the help of hydrogen to generate a stable product.
MRPL is having two hydrocrackers which produce ultra-pure diesel by processing High Sulphur Vacuum Gas Oil. The unit operates at 190 kscg pressure while the feed reacts with hydrogen for the production of lighter products.
c.Hydro-Treating: Under hydro-treating process, the impure lighter products such as naphtha, kerosene and diesel products are treated over a catalytic surface in presence hydrogen to remove harmful Sulphur and Nitrogen. Thus, treated products will have very low Sulphur.
In MRPL, there are two Diesel hydrotreating units, wherein treatment in the presence of hydrogen yields ultra-low Sulphur diesel. These units operated in the range of 60kscg to 110 kscg pressure range and provided with highly heat integration systems. Besides, Coker Gas Oil, Light Naphtha and Heavy Naphtha are hydro-treated in their designated units before processing further. The Coker Heavy Gas oil unit is a unique unit in India, which is designed to operate with 100% Heavy Gas oil from Delayed Coker Unit.
Dedicated diesel blenders are used for the optimisation of the product diesel and value addition.
d.Reforming and Isomerisation: Gasoline feedstocks are treated to increase their octane rating, which is a measure of its resistance to detonation, based on a scale of 0 to 100. (Engine knocking occurs when the fuel in an internal combustion engine ignites spontaneously with no input from the spark plug.) If the octane rating isn’t high enough, the engine will eventually be irreversibly damaged. To avoid this, it is necessary to boost the octane rating to 95 or 98. The process used to produce high-octane products is called catalytic reforming. The process of reforming uses platinum-based catalyst converts naphthenic hydrocarbons (saturated cyclic hydrocarbons) into aromatic hydrocarbons (unsaturated cyclic hydrocarbons), which have a much higher-octane rating. Thus, the reformed product is further split into light and heavy reformate to concentrate RON molecules. With these reformers, MRPL was first in India producing lead-free high-octane Gasoline in India from 1996.
In addition to reforming, Isomerisation process is also used to boost RON of Lighter Naphtha component and provides blending stock for Gasoline production.
MRPL is having two Continuous catalytic Reformers followed with common Reformate splitter unit. Besides, Mixed Xylene unit further separates BTX components to provide feedstock to Aromatic complex.
Isomerisation Unit in MRPL treats the light naphtha components from various units and adds value in terms of upgrading them into Gasoline blending stock.
Dedicated MS blender in the refinery, optimises the Gasoline feedstocks and improves the value of lighter naphtha streams.
e.Thermal Cracking: The process wherein the heavier feedstock is cracked neither with catalyst nor with hydrogen and instead just application of heat is called thermal cracking. Short Residue or bottoms from distillation units are normally thermally cracked to generate lighter products.
MRPL is having two mild thermal cracking units, namely Visbreakers and one deep thermal cracking, Delayed Coker Unit (DCU). The Delayed Coker Unit deploys four coke drums wherein the residual carbon from heavy hydrocarbon chain is solidified and separated. The unit is provided with a hydraulic coke cutting system along with dedicated coke water separation system.
f.Bitumen Blowing: Short Residue from Distillation column bottom is oxidised using dedicated reactor using air to produce viscosity grade bitumen. The grade of the bitumen depends on the amount of volatile material that remains in the product: the smaller the number of volatiles, the harder the residual bitumen.
MRPL has a bitumen blowing unit which produces VG30 and VGO40 grade of bitumen.
Treating involves removal of molecules that are corrosive or cause air pollution, especially Sulphur and nitrogen. Since 1st of April 2020, Gasoline and Diesel sold in India cannot contain more than 10 parts per million (ppm) , or 10 milligrams per kilogram, of Sulphur, the treating and purification is very important. The purpose of these processes is to reduce the emission and extract/destroy the impurities.
The treating process in the refinery is done through Amine Sweetening and extraction of Sulphur in the Sulphur recovery unit. MRPL is having six Sulphur Recovery Units (SRU) to recover Sulphur from various products generated in the refinery. These SRUs also handle Ammonia gases which are derived due to the presence of nitrogen in the fuel produced.
In addition to SRUs, there are caustic washes and MEROX units for reduction of harmful Hydrogen Sulphide and Mercaptans in the fuel. Dedicated spent caustic handling unit in unit reduces odour and concentration before disposal.
As a part of value addition, the refinery has a Polypropylene unit, wherein the Propylene gets treated through Zigger-Natta Process to generate polypropylene pellets. Polypropylene is a long chain polymer made from propylene monomers. After exposing the Propylene to both heat and pressure with an active catalyst, the propylene monomers combine to form a long polymer chain, called polypropylene. The polymer properties are adjusted by the feed rate and type of catalysts, co-catalysts, stereo modifier, hydrogen & additives.
- Offsites and Utilities
For receiving, storing and feeding crude and various products to and from the refinery, tankages and pipelines are needed in a refinery. While LPG is stored in the bullets, dedicated floating and fixed roof tanks are needed depending on the type of the content of the tank.
The refinery is connected to the all-weather port at New Mangalore. Fully laden ships up to 245m length (90000 T) can be berthed in the Jetties. Coastal movement through New Mangalore Port through pipeline connectivity is provided for the refinery. Further Single Point Mooring System of the refinery can berth Very Large Crude Carriers (VLCCs).
In addition, Mangalore-Hassan-Bangalore Pipeline is available for transferring product from the refinery to hinterlands of the state.
For supporting hydrogen requirements in the refinery, hydrogen generators are needed in the refinery. These hydrogen generation units utilise steam methane reforming process and generate hydrogen with 99.9% purity.
MRPL has three Hydrogen generation Unit inside the refinery complex.
Power requirements of the refinery are met by dedicated Cogeneration Power Plant of the refinery. The Power Plant is equipped with both Boiler-Steam turbine generators as well as Gas Turbine-Heat Recovery Steam Generators to optimise fuel requirements.
In addition, support facilities such as Cooling Towers, Demineralisation Water Plants, Nitrogen and air systems help in sustaining refinery operation.
The refinery receives freshwater from Netravati river as well as treated sewage from Mangalore City Corporation. Dedicated Reverse Osmosis facilities are provided to upgrade treated sewage water to Demineralisation feed quality inside the refinery so that freshwater consumption is optimised. New Desalination plant is getting erected and will be functional soon.
Unique Features of MRPL
- First in India to produce BSVI grade fuel quality both for diesel and Gasoline
- Refinery capable of processing most difficult crudes from 18 API (blended) to 46 API gravity and light to heavy/sour to sweet crudes. Further high TAN crude can be processed directly without any additives in one of the crude and vacuum distillation unit.
- NABL certified laboratory inside the refinery complex for product analysis.