FO/LDO storage tank heater and oil circulation heater with pumping system skid for sponge/steel plant


Marathon Process Heaters are tailored to meet customers’ unique needs.  Products are engineered to provide Energy efficient, precise process temperature control and built with quality to operate for decades in service.  Immersion and Circulation heaters can be adapted to match any heating need with liquid or gas. Common applications include Furnace oil, LDO, crude oil, acidic solutions, potable water, steam, industrial, hydrocarbons, hydrogen, oxygen, and superheated air.


Common applications include Furnace oil, LDO, crude oil, hydraulic fluid, acidic solutions, potable water, industrial gases such as hydrocarbons, hydrogen, high oxygen content, or superheated air. Used in almost in process of all Industry- Aluminum, steel, oil and gas, fertilizer, cement, tyre, etc.

Sponge iron

Removing oxygen from the ore by a natural process produces a relatively small percentage of steel in the world. This process uses less energy and is a natural chemical reaction method. The process involves heating the naturally occurring iron oxide in the presence of carbon, which produces “sponge iron.” In this process, the oxygen is removed without melting the ore. Iron oxide ores extracted from the Earth are allowed to absorb carbon by a reduction process. In this natural reduction reaction, as the iron ore is heated with carbon, it results in a pop-marked surface, hence the name “sponge iron.” The commercial process is a solid solution reduction, also called direct-reduced iron (DRI). In this process, the iron ore lumps, pellets, or fines are heated in a furnace at 800–1500°C (1470–2730°F) in a carburizing environment. A reducing gas produced by natural gas, fuel oil, or coal, and a mixture of hydrogen and carbon monoxide gas, provides a carburizing environment.

The overall process extends to a period of 10 to 12 hours inside the kiln. During this time, iron ore is optimally reduced and the hot reduced sponge iron along with semi-burnt coal is discharged to a rotary cooler for indirect cooling to a temperature of around 120°C. Sponge iron being magnetic in nature, the discharge from cooler main drive consisting of sponge iron, chars & other contaminations are routed through electromagnetic separators, to separate other impurities from sponge iron.

The kiln is provided with an oil burner located at the axis of the kiln at the discharge end Four thermo-couples are fitted in the kiln at various distances from the burner end for continuous recording of the temperature inside the kiln. By proper adjustment of the oil burner as well as the con-trolled amount of secondary air the desired temperature profile in the kiln can be maintained.

Alternative fuel oil firing should be provided at the firing end at a variable rate through two burners. The oil burners should be one on either side of the pulverized coal burner in the center of the firing hood. Even though coal is a cheaper fuel, the capital and maintenance costs of coal firing are higher than oil firing.

A central burner located at the kiln discharge end is used with Light Diesel Oil (LDO) for heating the cold kiln. After initial heating, the fuel supply is turned off and the burner is used to inject air for coal combustion.

Heavy fuel oil tanks are also provided with suction heaters with steam as the heating source to heat the oil before sending it to transfer pumps. The fuel oil unloaded into main storage tanks is transferred to the day oil tanks for sending it to oil pressurizing station from where it is sent to the burners, as and when required. The oil is transferred from the main oil tank to Day oil tank using the transfer pumps. During this process, the fuel is freed from mechanical impurities by means of filters. The provision of a day tank may not be required where fuel oil tanks are located close to boilers.

Fuel oil needs to be heated for handling and storage purpose. Heating oil in tanks and pipe above the temperature needed for storage and handling should be avoided as this waste energy.

Tanks and oil pipe in the open should be insulated and weatherproofed and steam and heat tracing applied to maintain minimum handling temperature.

In an electric heater, control is achieved by a thermostat and sensing device mounted on a tube plate, with the sensor directly in the path of oil flowing from the heater. The control setpoint is set at the required oil temperature and the required safety thermostat is set at 20 degrees higher temperature to compensate for the differential between the two instruments. Should the control system fail while in the ON position, the safety thermostat acts as a master cut out and switched the heater off.

Advantage of Marathon heating system

Marathon in-house design, engineering, and fabrication allows for almost an unlimited possibility of customized/standard applications. Electric heating provides the best option for superheating as its power is instantly available, has no emissions, and is precisely controlled to only the demand needed. Our design and engineering study your data and provide the best energy-efficient heating solutions.

Marathon Oil circulation system generally consist with —

  1. Electric Heater with element assembly, with Pressure Vessel
  2. Electric Heater bundle for Tank immersion heating application.
  3. Terminal assembly for the Electric Heater bundle suitable for the safe area – IP 54 for each Bundle
  4. Element skin temperature sensors  & process (outlet) Temperature sensors – As required
  5. The pump of suitable LPM flow for FO / LDO flow from Tank to the heater (2 each)
  6. Pump for suitable LPM flow for FO / LDO unloading purpose (Loose supply)
  7. Piping between Heater pumps and Electric Heaters for FO & LDO (In line heaters).
  8. Thyristor Control Panel (local control panel) suitable for safe area installation - for Circulation  Heater
  9. Thyristor Control Panel (local control panel) suitable for safe area installation - for Immersion Heater
  10. MS base frame skid for mounting Heater Unit & Control Panel along with internal wiring between heater and control Panel.

Typical marathon scheme for FO/LDO oil circulation heating system –