Caterpillar 793 mine truck with the GFS EVO-MT system installed

EVO-MT® 9920 | LNG Conversion for Caterpillar 992 Wheel Loaders

The EVO-MT^® System enables operators of Caterpillar 992 wheel loaders to substantially reduce operational costs and improve sustainability by substituting diesel fuel with lower cost, cleaner burning natural gas. The EVO-MT^® System is comprised of patented and proprietary technologies that allow haul trucks to safely operate on gas percentages that represent a substantial portion of their total fuel requirement. The EVO-MT^® System has been designed around an LNG on-board storage capacity equivalent to 50% of the normal diesel fuel consumed over a single shift of operation. Diesel Displacement Rate (DDR) will vary according to the specific duty cycle of the wheel loader. Typical DDR for most wheel loader profiles ranges between 35% and 50%. Wheel loaders converted to LNG + diesel operation exhibit diesel-like performance in such critical areas as power, response and efficiency.

Engine Conversion

The EVO-MT® System allows for the in-frame conversion of the wheel loader engine to LNG+D operation. The conversion process utilizes components that are installed externally of the engine and no changes or modifications to the cylinders, pistons, fuel injectors or cylinder heads are required. Retaining the OEM diesel fuel system in its entirety, the engine maintains the capability to operate solely on diesel fuel when required. The System interfaces with the engine cooling circuit in order to supply high temperature coolant to a heat exchanger / vaporizer for efficient conversion of the LNG from a liquid to a vapor state. Once the LNG is converted to a vapor phase, it is supplied to the engine’s air-intake system at a point upstream of the turbo-compressor inlet using low restriction air-gas mixing technology. Installation is performed using conventional shop tools and equipment and requires about 6 - 8 hours to complete.

Protection and Control

The EVO-MT® System includes a powerful Electronic Control Unit (ECU) that monitors critical engine, chassis and system data and uses this information to dynamically control the operating fuel mode of the engine. The ECU also provides sophisticated engine protection and monitoring functionality with pre-alarm, alarm and shut-down logic that allows the engine to be switched from NG+D® mode to diesel-only operation seamlessly and automatically. These protective systems and control algorithms ensure continued engine reliability and uptime when operating on LNG. The ECU monitors critical engine parameters including exhaust gas temperature, manifold air temperature, vibration, engine coolant temperature, engine speed, compressor inlet pressure and manifold air pressure. Each ECU data channel is sampled 50 times per second (50 Hz) ensuring rapid detection and correction of anomalies.

Graphical User Interface

The GUI allows for quick and simple access to both real time and logged system data using a proprietary graphical user interface (GUI) program. The GUI program is PC compatible and technical personnel can access System data using a convenient USB interface located in the operator cab. In addition to accessing System data, the GUI program is utilized during setup and commissioning of the haul truck for creation or loading of fuel mapping algorithms as well as for programming various System control, pre-alarm and alarm setpoints.

On-Board LNG Storage

LNG is safely and securely stored onboard the wheel loader using a fully-integrated chassis system. The LNG storage “module” includes double walled, vacuum insulated cryogenic tanks, LNG vaporizers, cryogenic safety controls, high and low pressure gas regulators and sensors. The module is a fully-engineered, pre-fabricated assembly that significantly minimizes the required installation down-time of the truck. Fuel storage modules are shipped to the mine site completely assembled and tested and can be installed using overhead shop cranes or mobile lifting systems. The LNG module is designed for specific wheel loader configurations and/or duty cycles and normally includes sufficient LNG storage capacity for a 12 hour refueling cycle.

LNG Refueling

The LNG storage module is filled via a remote refueling receptacle that is located according to customer requirements. LNG refueling is performed using a pressurized, quick-disconnect coupling that allows for the safe and rapid refueling of the module. LNG refueling can be done in parallel with diesel refueling using either permanent, semi-permanent or mobile cryogenic fuel transfer systems.