Furnace Oil: Why This Refinery Byproduct Causes Sulphur Emissions

1.1 What is furnace oil?

Furnace oil is a dark, viscous residual fuel. Bharat Petroleum says it is made by blending mainly the heavier components from the crude distillation unit.

Refineries do not waste these heavy parts. Whatever is too heavy for petrol or diesel is still sold as fuel.

1.2 Why does the heavy part end up at the bottom?

A refinery heats crude oil and separates it in a tall tower. The US Energy Information Administration says heavy fractions sit at the bottom and light fractions at the top.

The heaviest fractions have the highest boiling points. They settle at the bottom of the tower. Residual fuel oil is the name for the heavier oils that remain after the lighter ones are distilled away.

1.3 How is furnace oil graded in India?

Indian Standard IS 1593:2018 sets the grades. Bharat Petroleum lists four of them: LV, MV1, MV2 and HV.

The grades differ in viscosity. IndianOil’s table gives kinematic viscosity at 50 °C in centistokes:

• LV: 80 at most.
• MV1: 80 to 125.
• MV2: 125 to 180.
• HV: 180 to 380.

1.4 Who burns furnace oil?

Industry burns it for heat and power. Bharat Petroleum names these main uses:

• firing boilers
• thermic fluid heaters
• industrial furnaces, including foundry and glass furnaces
• slow-speed engines for captive power generation

A 3 March 2017 affidavit by the Environment Ministry cited the NEERI report. It said cement and other industries with proper SO₂ and NOx controls may use furnace oil and pet coke. EPCA disagreed. Its first recommendation was a strict ban on selling and using both in the NCR. The Court’s order of 24 October 2017 banned both fuels in the NCR.

Hindustan Petroleum adds that its LSHS is used mainly in heavy industry, steel plants and power plants.

2.1 Where does the sulphur go in refining?

EPCA made a sharp point in 2017. As India makes cleaner petrol and diesel, the sulphur is pushed into the bottom-of-the-barrel fuels. Those fuels are furnace oil and pet coke.

So the cleaner the diesel, the dirtier the leftover fuel can be.

2.2 How much sulphur does furnace oil hold?

IS 1593:2018 allows a maximum of 3.5, 4.0, 4.0 and 4.5 per cent sulphur by mass. These are the limits for LV, MV1, MV2 and HV. Bharat Petroleum’s MV2 sheet gives a maximum of 4.0 per cent.

One per cent is 10,000 ppm. So these limits are 35,000 to 45,000 ppm.

EPCA’s 72nd report gives lower figures. It says furnace oil has between 15,000 and 23,000 ppm of sulphur. Pet coke has 69,000 to 74,000 ppm.

2.3 How does that compare with diesel?

EPCA called 10 ppm low-sulphur in 2017. It said BS-IV fuels nationwide then held only 50 ppm. Down To Earth reports that BS-VI fuel, which it reported was set to start on 1 April 2020, holds just 10 ppm.

EPCA’s 1996 list of acceptable fuels had defined low sulphur as 18,000 ppm. That list named fuels such as LSHS. EPCA said this old wording became a loophole.

2.4 What happens when the sulphur burns?

Burning sulphur-rich fuels releases sulphur dioxide. A 2024 study in Scientific Reports says burning sulphur-rich fossil fuels such as coal contributes significantly to SO₂.

The US EPA says SO₂ and other sulphur oxides can contribute to acid rain. It also says the largest source of SO₂ is the burning of fossil fuels by power plants and other industrial facilities.

2.5 Why do industries still buy it?

Money is the reason. EPCA says furnace oil is priced lower than natural gas so that it stays competitive.

It gave 2017 costs of power. Furnace oil came to about Rs 5 to 6 per unit. Natural gas and electricity were each about Rs 6 to 7 per unit.

3.1 What did the Supreme Court have in front of it?

EPCA filed its 72nd report in April 2017. The report quotes the Court’s order of 2 December 2016 on use of these fuels for industry and power.

The report’s main numbers are the ppm figures above. EPCA also said enforcement had to be stepped up, and that illegal use of these fuels in Delhi had to stop.

3.2 What happened on 2 May 2017?

The Tribune (New Delhi) reported this on 31 October 2017. The Court’s 2 May 2017 order, it said, had noted that use of furnace oil and pet coke was prohibited in Delhi. S.S. Rana, a law firm, says the 2 May order prohibited their use in Delhi.

EPCA’s record also says pet coke and furnace oil were already prohibited in Delhi.

3.3 What did the Court order on 24 October 2017?

EPCA’s 76th report says the Court banned the use of pet coke and furnace oil in the NCR from 1 November 2017. The order is dated 24 October 2017.

EPCA’s clarification, sent to the Chief Secretaries on 27 October 2017, said the ban covered the NCR districts of Uttar Pradesh, Haryana and Rajasthan.

3.4 What else did the order say?

• Industries were asked to meet the draft MoEF&CC standards by 31 December 2017.
• EPCA says CBFS is also banned as a fuel, because oil companies told EPCA it is another name for furnace oil.
• EPCA says pet coke may still be used as feedstock, but not burned for fuel.

3.5 Was this a national ban?

The orders named Delhi and the NCR. The sources used here describe no nationwide ban.

4.1 What is LSHS?

LSHS stands for Low Sulphur Heavy Stock. Bharat Petroleum’s sheet gives a maximum of 1 per cent total sulphur by mass. It says the product conforms to IS 11489:1985 (Grade 1) for heavy petroleum stock.

Hindustan Petroleum gives a different cap. It says LSHS has a maximum of 1.8 per cent sulphur, as per customer need. So there is no single number for all makers.

4.2 How is it different from furnace oil?

Furnace oil under IS 1593:2018 can hold up to 3.5 to 4.5 per cent sulphur. LSHS limits are 1 to 1.8 per cent. Bharat Petroleum says its premium LSHS is a residual fuel processed from low-sulphur crude.

4.3 What is LSFO?

LSFO is Low Sulphur Furnace Oil. IndianOil began deliveries of IMO 2020-compliant LSFO with 0.5 per cent sulphur as marine fuel at Indian ports.

The first such supply was on 26 October 2019. It went to the LPG tanker Berlian Ekuator at Kandla port.

BPCL’s Kochi refinery began making a similar very-low-sulphur fuel in December 2019. It sent India’s first IMO 2020-compliant export, 15,000 tonnes, to Singapore on 7 February 2020. OGJ says this fuel is made mainly from the vacuum residue of low-sulphur crudes.

5.1 What does a ship burn?

The IMO says heavy fuel oil is derived as a residue from crude oil distillation. It had a much higher sulphur content. Furnace oil is also a residual fuel, as section 1 showed.

5.2 What did IMO 2020 change?

From 1 January 2020, ships outside designated emission control areas must use fuel with at most 0.50 per cent sulphur. The IMO calls this a significant reduction from the previous limit of 3.5 per cent.

Inside emission control areas the limit was already stricter, at 0.10 per cent.

The IMO adds that sulphur oxides can lead to acid rain. IndianOil describes its LSFO as IMO 2020-compliant.

5.3 Which fuel is replacing furnace oil on land?

EPCA says the key substitutes for furnace oil and pet coke are natural gas and electricity. It also says there are no emission standards for natural gas, because it is accepted as cleaner, with no PM or SO₂ emissions.

The shift has not been quick. In 2017, gas companies told EPCA that pipelines were laid and gas was available. But demand was low, because furnace oil and pet coke were cheaper.

5.4 What can we say today?

These sources are from 2017 to 2020. They do not measure how many industries have switched since. This lesson therefore does not claim a current trend.

What the sources do show is the direction. Sulphur rules for ships tightened in 2020. Courts and regulators in 2017 pointed industries in the NCR towards gas and electricity.