DUAL FUEL ENGINES- Rethinavel Pandi

Wärtsilä dual-fuel engines

The Wärtsilä dual-fuel engines are unique because they have two different injection systems. A micro pilot injection system injects a very small amount of liquid fuel when the engine is operating in gas mode. The micro pilot system is of the common rail type, which allows for very small injection amounts.
This makes it possible to meet very stringent emission regulations, which would be impossible if a normal injection system were used. A conventional injection system is used when the engine is run on liquid fuel such as heavy fuel oil or of course diesel oil if that is the fuel choice. Fuel flexibility and high efficiency are the main advantages of the dual-fuel technology. Two engine models are offered at the moment, the Wärtsilä 32DF and Wärtsilä 50DF. The latter has shown an efficiency of over 48%, which is probably a record at this time.


                 Wärtsilä gas-diesels were the first gas engines offered by the company. The first engines have now been in operation for almost 70,000 h. The concept was initially developed for the offshore market, where it has been successfully applied in a large number of floating production units. However, these engines have also been used in numerous power plants because of their fuel flexibility. In the gas diesel the gas is injected according to a diesel process at high pressure. A small amount of liquid fuel is pilot injected when the engine is operating in gas mode. A gas diesel can operate on gas with pilot injection and also on liquid fuels such as diesel oil, heavy fuel oil or even crude oil. In gas mode the gas diesel is more tolerant in terms of methane number than other gas engine concepts. Wärtsilä's gas-diesel engines are the Wärtsilä 32GD and Wärtsilä 46GD.


Engine working principle of dual-fuel (DF) engines 

                  The dual-fuel engine utilizes a “lean-burn” otto combustion process when operating on gas. Here, the gas is mixed with air before the intake valves during the air intake period. After the compression phase, the gas/air mixture is ignited by a small amount of liquid pilot fuel (LFO). After the working phase the exhaust gas valves open and the cylinder is emptied of exhaust gases. The inlet air valves open when the exhaust gas valves close, and the process starts again.

            The dual-fuel engine is also equipped with a backup fuel system. In the event of a gas supply interruption, the engine transfers from gas to fuel oil operation (LFO, HFO) at any load instantaneously and automatically. Futhermore, the separate backup fuel system makes it possible to switch over from LFO to HFO without load reduction. During fuel oil operation the DF engine utilizes the conventional diesel process.


             

Engine working principle of gas-diesel (GD) engines

                      The GD engine utilizes the diesel combustion process in all operational modes. In gas mode, the gas is injected at high pressure after the pilot fuel and is ignited by the flame from the pilot fuel injection. The amount of pilot fuel is equivalent to approximately 5% of the fuel energy input at full engine load.
The gas-diesel engine can be switched over instantly to liquid fuel mode operation. The liquid fuel can be light fuel oil, heavy fuel oil or crude oil. In this case, the process is the same as the conventional diesel process.
In fuel sharing mode, the ratio between liquid and gas fuel amounts can be controlled and varied during operation. The operating window for the fuel sharing mode is 30 to 100% load and the gas/liquid fuel ratio can vary according to the fuel sharing window.
The gas-diesel process can tolerate big variations in the gas quality and is especially suitable for “non-pipeline quality gas”, such as associated gas in oil fields.
 

Wärtsilä 32GD main technical data

The Wärtsilä 32GD has been developed to set new standards in the market for high
performance, fuel-flexible engines. The Wärtsilä 32GD is a four-stroke, gas-diesel
engine, which means that the engine can run on either gas or fuel oil according to the diesel cycle. Switching from one fuel to the other can be done under all operating conditions.
The Wärtsilä 32GD covers a power range of 2520 – 8400 kW. The engine runs at 720 or 750 rpm for use with 50 or 60 Hz generators and produces 405 – 420 kW per cylinder.
The main features of the Wärtsilä 32GD are:
• Low-NOX combustion
• Reliability and low maintenance costs
• Integrated monitoring and control or basic
automation system
• Ergonomic interface
• Minimized consumables
• Unique fuel flexibility

Technical data 50 Hz/ 750 rpm		6L32GD	9L32GD	12V32GD	16V32GD	20V32GD
Power, electrical	kW	2636	3974	5327	7124	8924
Heat rate	kJ/kWh	8304	8260	7840	7815	8049
Electrical efficiency		43.4	43.6	44.5	44.6	44.7
Technical data 60 Hz/ 720 rpm
Power, electrical	kW	2579	3888	5184	6970	8730
Heat rate	kJ/kWh	8304	8260	8091	8066	8049
Electrical efficiency	%	43.4	43.6	44.5	44.6	44.7
Dimensions and dry weight of generating sets
Length	mm	8400	10400	10200	11300	12890
Width	mm	2780	2780	3300	3300	3300
Height	mm	3840	3840	4470	4240	4440
Weight	tonne	58	77	92	120	130

Wärtsilä 34DF main technical data

The WÄRTSILÄ® 34DF tri-fuel engine is the ultimate ‘fuel flexibility’ engine. The Wärtsilä 34DF is a four-stroke dual-fuel engine that can be run on natural gas, light fuel oil (LFO) or heavy fuel oil (HFO).
Moreover, the engine can switch over from gas to LFO/HFO and vice versa smoothly during engine operation. The Wärtsilä 34DF is manufactured in configurations from 6L up to 20V giving 435/450 kW per cylinder and a total maximum mechanical output of 9000 kW. The engine speed is 720 or 750 rpm for use with 50 or 60 Hz applications.

Technical data 50 Hz/750 rpm		6L34DF	9L34DF	16V34DF	20V34DF
Power, electrical	kW	2579	3888	6970	8730
Heat rate	kJ/kWh	8347     (8257)*	8303     (8214)*	8048    (8146)*	8031    (8127)*
Electrical efficiency	%	43,1 (43,6)*	44,4 (43,8)*	44,7 (44,1)*	44,8 (44,3)*
Technical data 60 Hz/720 rpm
Power, electrical	kW	2493	3758	6737	8439
Heat rate	kJ/kWh	8347 (8217)*	8303 (8175)*	8048 (8107)*	8031 (8127)*
Electrical efficiency	%	43,1 (43,8)*	44,4 (43,8)*	44,7 (44,4)*	44,8 (44,3)*
Dimensions and dry weight of generating sets
Length	mm	8400	10400	11300	12890
Width	mm	2780	2780	3300	3300
Height	mm	3840	3842	4240	4440
Weight	tonne	58	77	120	130

Wärtsilä 50DF main technical data

The Wärtsilä 50DF tri-fuel engine is the ultimate ‘fuel flexibility’ engine.
The Wärtsilä 50DF is a four-stroke dual-fuel engine that can be run on natural gas, light fuel oil (LFO) or heavy fuel oil (HFO). Moreover, the engine can switch over from gas to LFO/HFO and vice versa smoothly during engine operation.
The Wärtsilä 50DF has a total maximum mechanical output of 17,100 kW. The engine speed is 500 or 514 rpm for use with 50 or 60 Hz applications. The engine has a maximum thermal efficiency of 47%.

Technical data 50 Hz/500 rpm		18V50DF	18V50DF*
Power, electrical	kW	16638	16638
Heat rate	kJ/kWh	7616	8185
Electrical efficiency	%	47.3	44.0
Technical data 60 Hz/514 rpm
Power, electrical	kW	17076	17076
Heat rate	kJ/kWh	7616	8185
Electrical efficiency	%	47.3	44.0
Dimensions and dry weight of generating set
Length	mm	18780	18780
Width	mm	4090	4090
Height	mm	6020	6020
Weight	tonne	355	355
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