Gensets running on oil and residual fuel oil: prices and characteristics

A genset running on crude oil is a power unit, which generates electricity by combusting fuel in the internal combustion engine by rotating the generator. Thanks to this, the genset can run completely independently and provide remote areas, which are not connected to the common power network, with electric power.

Features of crude oil when used as fuel

A classical diesel generator cannot use crude oil ad fuel. A common internal combustion engine is arranged in such a way that for the normal operation of all components it needs fuel with certain parameters.

Oil as distinct from diesel oil has the following characteristics:

• The high viscosity of the liquid. The fuel system of a common diesel generator in a power plant cannot pump a liquid with a viscosity of more than 12 cSt. Therefore, if crude oil is used, it is necessary to pre-heat it to increase fluidity.
• The presence of flying fractions. Unlike diesel fuel, oil is a multifraction fluid. Therefore, before sending it to the cylinders, it is necessary to solve the issue of separating light fractions so that only the liquid part falls into the combustion chamber.
• Contaminants and water. Oil, before its processing at oil refineries, contains a large number of insoluble particles and water, which negatively affect the resource and stability of the ICE. Therefore, you need to take care of reliable filtration using a filter system.
• Destructive effects of impurities. When the crude oil burns, it adversely affects the engine components and quickly disables them. Frequent repairs bring the advantages of using gensets to naught. To prevent the problem in the ICE, valves made of heat-resistant steel with welding deposition and a turning mechanism are used. The latter is needed for the constant grinding-in of the parts.

Gensets running on residual fuel oil: specification of engine, generator, operation principle

Price for gensets running on residual fuel oil 1640 kW, 10,5 kV – $2 million (VAT included).

Gensets running on residual fuel oil do not require mandatory pre-treatment of fuel, and this unit costs half of the price of a genset - $800 000.Discuss the project

A power genset generates a large amount of power, which in turn allows the use of the released heat using raw hydrocarbons.

The 9CM20 generator units were made at the Caterpillar Motoren factory in the city of Kil, Germany. Each unit consists of a 9CM20C engine, united on the same frame with a three-phase, two-bearing synchronous generator, 50 Hz, IP23, power - 2050 kVA. The dimensions of every unit: 7,1 m (length) x 1,8 m (v) x 3,4 m (height), weight (dry) 26 tons.

Fuel preparation container

To ensure the pretreatment of fuel and its supply to the units, a fuel preparation container is provided in the fuel system. The main task of this unit is to ensure the purification of fuel from water and mechanical impurities using a centrifugal separator, as well as its supply to the circulation modules of the units.

The main equipment installed in the container:

• Forcing module
• Fuel separator
• Nitrogen generator with compressor
• Control system

For safety reasons, the container is divided into two areas: the Explosive Zone with all fuel equipment and the Safe Zone for the control system and nitrogen generator.

The AlfaLaval separator specially designed for oil operation ensures the guaranteed separation of water and dissolved particles from oil, as well as the purification of fuel from mechanical impurities. The main feature of this separator is its capacity to work with fuel containing light fractions evaporating during the purification of fuel.

The dual design of this separator ensures the high reliability of the equipment due to 100% redundancy.

To ensure the operability of the separator, there is a nitrogen generator with an electric compressor in the fuel preparation container. The inert gas produced by the generator provides an air cushion inside the separator and also rules out the possibility of explosive mixture formation.

During operation, the separator takes fuel from the crude oil tank and delivers the cleaned fuel to the service tank. At the same time, to exclude the operation of the separator in the start-stop mode when filling the service tank during the operation of the station at low load, which is extremely negative for the separator, an overflow line is provided between the service tank and the crude oil tank. This solution ensures the non-stop operation of the separator, except for scheduled outages.

The injection module is designed to provide oil and diesel fuel supply to the circulation modules of the genset, while creating the necessary pressure and providing the necessary fuel supply.

The design of the module provides for 100% redundancy of the main fuel pumps. The valves are controlled pneumatically to meet the requirements for explosion safety.

In the process of operation, the injection module takes fuel from the service tank and delivers it to the units.

The performance of the injection module ensures fuel consumption at any level of generated power.

Fuel preparation container requires connection of fuel lines and auxiliary power supply.

Engine SM-9SM20S

The generator drive is an engine of the 9SM20S model produced by Caterpillar Motoren. This engine type is developed specially for running on oil and residual fuel oil. For over 20 years, it has been used on ships and in the production of gensets. Main features: long piston stroke, dry engine block made from a solid piece of spheroidal graphite iron, individual 4 valves per cylinder.

The engine is four-stroke, with direct injection, turbocharging and an intercooler. The long piston stroke of the engine ensures complete combustion of heavy fuel with a reduced content of harmful emissions and reduces fuel consumption. Improved combustion ensures advanced efficiency and reduced engine heat output.

• Developed for operation on heavy fuel as consistent with CIMAC H55 K55, ISO 8217.
• Dry engine block made of nodular cast iron, including crankshaft and camshaft bearings, charge air inlet, damper housing, and drive gears.
• Underslung crankshaft with anti-corrosion treatment of main and connecting rod bearings.
• Hardened sleeves with calibrated insert
• Composite piston with steel crown and cast iron bell
• A kit of pistons consisting of 2 chrome-plated compression rings. The upper one with the ceramic contact surface, the lower one is an oil scraper ring. All rings are hardened and installed in the steel crown of the piston.
• Two-piece connecting rod with the toothed connection.
• The cylinder head component made of nodular cast iron has 2 intake and 2 exhaust valves with a rotation mechanism.
• Forced cooling of exhaust valve seats.
• The turbocharger does not require forced water cooling.
• Dual-cycle circuit cooling system with boost air cooler.

Fuel system on the engine – Oil/Residual fuel oil (CRO) & Diesel (DFO)

• Separate fuel-injection pump for every cylinder.
• Double-wall high-pressure pipelines to every cylinder.
• Lubricant oil cools down nozzles.
• Dual 34-micron filter with differential pressure control.
• A built-in air-powered drive stop cylinder for emergency shutdown.

Lubrication system

The lubrication system lubricates the engine crankshaft, cylinder head component and pushers, gears and the main moving parts of the engine. For crude oil operation, proper piston cooling is critical. The engine is mounted directly on the base frame without an oil sump.

• Oil pan

• The supply tank is built into the frame of the unit

The lubrication system consists of:

• Engine-mounted oil cooler
• Engine-driven oil pump
• Electric pre-lubrication pump mounted on the unit frame
• Automatic oil filter with differential pressure control mounted on the engine
• Oil pressure sensor
• 1385-liter service oil tank mounted on the unit frame

Cooling system

The cooling system is divided into two circuits, high temperature (HT) circuit, and low temperature (LT) circuit. НТ circuit withdraws heat from cylinder liners and cylinder head components. LТ circuit withdraws heat from the boost air cooler and lube oil via an oil heat exchanger.

The cooling system components mounted on the engine:

• Motor-driven HT circuit pump
• Motor-driven LT circuit pump
• Electrical jacket heater on the unit

Pneumatic starter

The engines are started by compressed air at a nominal pressure of 10 bar. The start is carried out by a direct supply of compressed air to the air starter mounted on the engine. The supply valve can be manually or electrically operated via a solenoid for remote start. The engine speed sensor determines the rotation speed to determine the moment for fuel feeding and then closes aerial lines as soon as the engine starts.

Delivering air to the engine

Air for сombustion is filtered, compressed in the turbo compressor and passes through a single-stage boost air cooler, which uses the LT cooling circuit for maximum efficiency. The engine is equipped with one axial-type turbocharger

The air-delivery system mounted on the engine consists of:

• Compressor on the turbine
• Boost air cooler
• Compressor cleaning device
• Inlet air shut-off valve

Engine exhaust system

The exhaust gas from each cylinder is collected in the common discharge manifold and delivered to the turbo compressor through the pipeline system. It spins the turbo compressor, which allows compressing air for combustion.

The turbo compressor is mounted on the opposite end of the engine from the flywheel to provide easy access for servicing. Bellows expansion joints are installed in the manifold piping system and between the turbocharger and the external chimney.

Speed control system

The engine speed control is carried out using an electronic regulator consisting of an electro-hydraulic drive and a speed sensor.

Inlet air shut-off valve

For operation on residual fuel oil and crude oil, the engine is equipped, for safety reasons, with a quick-acting valve on the air intake for emergency shutdown of the engine when gaseous fuel enters the engine through the intake system. The valve completely blocks air from entering the engine, cutting off an uncontrolled external source of fuel and air. An air inlet shut-off valve is required when combustion air is taken inside a building and residual fuel oil and crude oil have a fuel flash point below 60o C. The air inlet shut-off valve is mounted between the engine turbo compressor and the manifold for air supply to the engine. The valve is controlled by compressed air.

Ventilation of fuel facilities

When operating diesel engines on crude oil and residual fuel oil, it is necessary to avoid the presence of gas vapor leaks from the oil around the high-pressure fuel pump. To this end, the entire area of ​​the fuel pumps is covered with a protective cover (so-called "Hot box") to isolate possible gas leaks.

To connect ventilation pipes there is a special nozzle with a flange. A flexible insert DN 150 and an electrically driven explosion-proof fan are included.

A vacuum-sensing device controls the ventilation operation to maintain the required rarefication. 

Generator

A three-phase two-bearing synchronous generator is developed for operation in the main mode in parallel with other generators. The generator and regulator comply with the requirements of ISO 8528.

Generator as a unit:

• Anti-condensation heater
• Thermal sensors PT 100: 2 x 3 for stator windings (1 x 3 on standby)
• Permanent magnet excitation
• Adaptation for parallel operation with similar generators
• Temperature sensors PT 100: 2 x for bearings
• Nipples for lubricating bearings
• Digital voltage regulator, MEC-100
• Docking with the engine via a flexible coupling
• Rotating bearings
• Power cable termination plug

Technical requirements for 1700 kW generators running on crude oil

Technical features of an IEC running on crude oil

The main difference between an oil engine (running on crude oil and other viscous fuel types) from the traditional diesel one is that the ignition of the fuel-air mixture occurs in the calorizer (hot bulb). This ICE element is heated in various ways to vaporize the fuel, which then ignites.

The engines are easy to maintain, reliable and can use different fuels without complicated reconfiguration. However, they are less efficient than diesel ones, operate at lower speeds and require reliable cooling. 

Download the manual for a generator running on oil>>>

Additional drawbacks to consider when manufacturing and operating gensets running on crude oil::

• Crude oil contains a large amount of sulfur, vanadium, and other contaminants, which cause fast corrosion of carbon steel. This reduces the service life of a power unit and requires more frequent scheduled maintenance.
• The complex hydrocarbons in the fuel cannot burn in the fuel when it is ignited in the IEC cylinders, so soot constantly accumulates in the exhaust system. This requires frequent system cleanings.
• When the engine is stopped, the viscosity of the fuel increases due to the lack of heating, which makes it impossible to restart after a long period (especially in winter), it should be started on light diesel fuel.

Manufacturing companies that produce gensets and/or power plants running on crude oil take into account the characteristics of this type of fuel and manufacture equipment that is adapted to the use of this type of hydrocarbon fuel.    

The main scope of use

Gensets running on crude oil are used in cases where there is a source of this fuel at a small distance from the place of its installation, and the delivery of common diesel fuel or gas is difficult because of no roads or a long distance from populated areas.

Techexpo gensets are installed

• As the main source of energy at facilities where crude oil is extracted by specialized enterprises;
• As an expansion module if the capacity of the existing energy source is not enough to meet all the needs of the mining enterprise;
• As a backup power source for mining companies in the event of a power cut from the centralized network due to breaks or for other reasons;
• As an electricity generating station for a settlement or several villages located in a remote area where it is economically inefficient or useless to run electric mains.

Genset design features

A genset consists of the next main components (they may vary depending on power and other characteristics):

• A generator, which generates alternating current.
• An internal combustion engine running on crude oil.
• Crude oil treatment unit and storage tank for it. It cleans the fuel from contaminants and removes some components that harm the internal combustion engine. The tank is necessary to create an operational supply of fuel for the generator.
• Power distributing equipment. It is used for commutating the genset with the power system of the facility, energy distribution management, as well as accounting for consumed electricity.
• Electronic control module, which controls the engine generator and auxiliary units providing the functioning of the unit.
• Storage tank for crude oil and/or diesel fuel, which is used to start up the system in winter. The tank may be equipped with a pump, which fills the container from the tank.
• Pneumatic engine starting system. It consists of a compressor and compressed air cylinders. The starting system can also be used to flush fuel equipment and filters from combustion products.

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The electronic control module provides:

• Starting up the genset and stopping the equipment if necessary;
• Changing modes of operation depending on the amount of consumed electrical energy;
• Switching the types of fuel on which the genset operates
• Control over the operation of components and notifying of their scheduled maintenance;
• Emergency shutdowns in emergency cases.

Techexpo gensets have two design options:

• stationary genset, which is mounted from individual parts on-site in a pre-built building.
• modular stationary power facility, all components of which are placed in a sea container for convenient transportation to the place of use.

Benefits

The main benefits of using gensets running on crude oil are:

• Fully autonomous operation. Using this genset you can provide remote facilities with electricity without standard engineering infrastructure.
• Possibility of manufacturing gensets of any capacity. If necessary, the power or number of crude oil generators can be increased depending on the needs of the connected facility or consumer group.
• Possibility of fast delivery to the site and deployment (for modular systems). All parts of the genset are mounted on a frame in a container, they can be transported by truck or helicopter. This approach speeds up the commissioning of the genset.

The main benefit is the possibility of operation at the local recourse with minimum consumption of diesel fuel. This makes it possible to cut the expenses of an oil-producing organization for electrification and increase the profitability of their operations. Built-in units are used for oil treatment, so there is no need to purchase and put into operation additional equipment.

Manufacturers of gensets running on crude oil

Techexpo partners offer gensets, which use crude oil as fuel, in the world market:

• Wartsila.
• MAN Diesel & Turbo. Компания изготавливает энергетические установки и двигатели на сырой нефти. Могут работать на добытой и предварительно подготовленной нефти, адаптированы для использования в современных электростанциях. Вырабатывают мощность до 4061 кВт, имеют 16 или 18 цилиндров.
• Hyundai Group. Изготавливают электростанции, работающие на мазуте, дизельном топливе, природном газе, сырой нефти. Могут работать в постоянном режиме, не требуют частой замены подвижных компонентов.  

Conclusion

Crude oil power plants have their own characteristics, and their operation is more complicated than conventional diesel fuel or gas generators. But they are almost the only alternative for facilities to which it is difficult to deliver diesel fuel by truck, and transportation by air is too expensive.

Crude oil gensets have their own characteristics, and their operation is more complicated than common generators running on diesel fuel or gas. But they are almost the only alternative for facilities where it is difficult to deliver diesel fuel by truck, and transportation by air is too expensive.

Techexpo provides additional services for assembling and maintaining gensets on-site. Buyers receive not only the gensets but also a full set of technological documents.