GFS EVO-SP dual fuel retrofit complete solution

GFS EVO-SP Dual Fuel System: Complete Guide for Natural Gas Transformation of Diesel Generator Sets

Against the backdrop of increasing electricity costs and environmental pressures, many users with backup or regularly operating diesel generator sets are seeking more economical and cleaner alternative fuel solutions. EVO-SP ™ The system emerged - it allows for the transformation of existing fixed diesel engines into natural gas diesel dual fuel (NG+D) operation, achieving a 50% to 70% diesel substitution rate without changing the original engine hardware, while maintaining diesel engine level load response, power output, and operational stability. This article will provide a detailed analysis of the technical architecture, installation process, core control logic, safety protection mechanism, and maintenance points of EVO-SP system from the perspective of engineering practice, providing a complete technical reference for power plant operators and on-site engineers.

System Overview: Why Choose EVO-SP Dual Fuel Transformation

The EVO-SP system consists of a series of proprietary and patent pending technologies specifically designed for fixed diesel generator sets (emergency power supply, peak shaving power station, islanded power supply, etc.). It achieves dual fuel operation through external additional components, without making any changes to the engine's cylinders, pistons, injectors, or cylinder heads, fully retaining the original pure diesel fuel system.

Core advantages:

Significant reduction in fuel costs (replacing some diesel with cheap natural gas)

Extend emergency operation time (dual fuel mode runs longer with the same fuel storage capacity)

Reduce carbon and particulate emissions to enhance sustainability

When natural gas supply is interrupted or abnormal, seamlessly switch back to 100% diesel mode without affecting power generation output

This system is suitable for scenarios using pipeline natural gas, with an intake pressure of only 3-7 PSI (approximately 0.2~0.5 bar), eliminating the need for high-pressure compressed natural gas (CNG) equipment and reducing on-site supporting requirements.

Hardware components and installation process

2.1 Main hardware components

The EVO-SP system consists of the following core components:

Electronic Control Unit (ECU)

32-bit microcontroller, integrated with USB and CAN communication, compatible with J1939 protocol. It monitors key parameters of the engine and generator in real-time, such as mass air flow rate, power generation, diesel flow rate, etc., and dynamically optimizes the gas substitution rate at a frequency of 50 times per second.

Touch screen control panel

12.1-inch TFT XGA LCD, IP65 protection level, installed in a NEMA 4X stainless steel housing, equipped with an external emergency stop button. It can display real-time data and historical records, support parameter configuration and diagnosis.

Air gas mixer and throttle body

Using a low resistance fixed geometry mixer, combined with an electronic throttle body, low-pressure natural gas is introduced into the intake duct. The mixer has a diameter of 6 inches and is made of 6061-T6 aluminum alloy. The gas interface is 1.5 inches JIC.

Dual module gas valve

DN65 caliber, 24~28 VDC power supply, switch time<1 second, in compliance with EN 161 Class A Group 2 standard, protection level IP54. Adopting dual redundancy, normally closed DC solenoid valve, and providing manual shut-off valve.

Safety Sensor Kit

Combustible gas detector

flame detector

Vibration (knock) sensor

Exhaust temperature sensor

Boost pressure/temperature sensor

Gas/diesel flow meters, etc

2.2 Key points of installation and construction

The EVO-SP system is completely externally installed and does not require entry into the engine interior. All components can be completed using pre configured wiring harnesses and military grade quick connectors with conventional tools. The typical installation time is 6-8 hours.

Step Overview:

Determine the installation position of the mixer on the intake pipe, usually located after the intercooler and before the intake manifold.

Install gas valve assembly (including dual solenoid valves, manual shut-off valves, pressure switches).

Arrange the gas pipeline from the natural gas source to the mixer, ensuring that the pressure is regulated to 3-7 PSI.

Install the ECU host and its wiring harness, and connect various sensors (which can use the J1939 CAN bus of the original engine to obtain diesel flow, speed, and other data).

Install touch screen panel and remote emergency stop button.

Connect a 24V DC power supply (subject to load surge protection requirements).

Perform leak testing and functional verification, and complete fuel mapping calibration.

Engineering Tip: The original engine retains pure diesel capability and can be switched back to diesel mode for testing or emergency power supply at any time during installation, without interrupting user power supply tasks.

Control strategy: dynamic substitution rate and real-time protection

3.1 Real time fuel mapping and optimization

Traditional dual fuel systems often use a fixed substitution rate, which is prone to misfire or detonation under high load or transient conditions. EVO-SP's ECU utilizes Dynamic Setpoint Protection ™） Technology has fundamentally solved this problem.

The ECU has a sampling frequency of up to 50 times per second and monitors over 25 sensor channels. It first records the benchmark performance curve of the engine in 100% diesel mode (exhaust temperature, vibration, air-fuel ratio, etc. under different loads). Subsequently, in dual fuel mode, the natural gas substitution rate and throttle opening are dynamically adjusted based on real-time load changes to ensure that key parameters always do not exceed the safety boundary of the benchmark curve.

The substitution rate is generally between 50% and 70%, depending on the engine model, load factor, and natural gas calorific value. The system will automatically optimize without manual intervention.

3.2 J1939 Communication and Integration

ECU is compatible with SAE J1939 protocol and can directly read the common rail pressure, fuel injection quantity, speed and other information of the electronically controlled diesel engine. For old mechanical engines, corresponding sensors (such as diesel flow meters and speed sensors) need to be installed to achieve closed-loop control.

3.3 Seamless Switching Logic

The system is equipped with multi-level alarm and shutdown logic:

Pre alarm: Parameters deviate from the normal range but are still controllable, only prompting the operator.

Alarm: Exceeding the safety limit but not immediately dangerous, automatically reducing the gas substitution rate.

Shutdown: In case of serious abnormalities (such as combustible gas leakage, flame detection, overspeed, high vibration, etc.), immediately close the dual solenoid valves and switch to 100% diesel operation without interruption.

The switching process is automatically completed by the ECU, and the output voltage and frequency of the generator will not fluctuate.

Security Design: Multiple Redundancy and Disaster Prevention Protection

Safety is the primary consideration for dual fuel retrofitting. The EVO-SP system has built a rigorous protection system from three levels: mechanical, electrical, and logical.

4.1 Gas valve group redundancy

The gas supply pipeline adopts double normally closed solenoid valves in series, and any valve failure may cause gas cut-off rather than accidental leakage. In addition, manual shut-off valves are provided for use during maintenance. This valve group has passed global mainstream certifications such as UL, UR, CSA, FM, CE, AGA, GOST, etc., meeting the strictest safety standards.

4.2 Combustible Gas and Flame Detection

Install combustible gas detectors and flame detectors around the generator. Once the methane concentration exceeds the standard or an open flame is detected, the ECU immediately performs the following actions:

Switch the engine back to pure diesel mode

Cut off the power supply of the dual solenoid valve

Send alarm signals to building control systems or fire protection systems through external interfaces

4.3 Explosion and mechanical protection

The system is equipped with vibration sensors (knock detection) and exhaust temperature sensors, which can detect detonation, premature ignition, or thermal overload in a timely manner. If a cylinder experiences abnormal high-frequency vibration, the ECU will reduce the gas ratio cylinder by cylinder until detonation is eliminated.

4.4 Electrical Protection

The ECU input power supply has:

Load sudden drop overvoltage protection (withstand>100V instantaneous overvoltage)

Undervoltage lockout (<18V shutdown output)

Reverse connection and dual battery voltage protection

Working temperature range: -40 ℃~+105 ℃

The touch screen panel has a protection level of IP65 (NEMA 4X for the entire machine) and can operate stably in humid and dusty environments.

Technical Specification Quick Reference Table

Key parameters of components

ECU 32-bit microcontroller, J1939 compatible, sampling 50 times/second, 24V power supply, IP56

Touch screen 12.1 "TFT, 1024 × 768, IP65, -20~60 ℃

Mixer 6 "aluminum alloy, 1.5" JIC inlet, -40~105 ℃

Gas valve DN65, 24-28VDC, switch<1 second, IP54

Environmental adaptability storage -40~125 ℃, random vibration 0.3G/Hz (10-2000Hz), impact 40G

Gas pressure 3-7 PSI (0.2-0.5 bar), pipeline natural gas

Substitution rate 50%~70% diesel replacement

Seamless conversion time,<1 second (valve closing time)

Engineering Application: Typical Scenarios and Benefit Analysis

6.1 Applicable Scenarios

Emergency backup power generation: In the case of limited diesel storage tank capacity, connecting to the natural gas pipeline network can extend emergency operation time by several days or even weeks.

Peak shaving power station: Utilizing the low period of natural gas prices to increase substitution rate and reduce marginal cost of power generation.

Island/microgrid: Reduce diesel supply frequency and improve energy self-sufficiency.

Environmentally restricted areas: Reduce NOx and particulate emissions to meet local environmental requirements.

6.2 Economic Benefit Estimation

Taking a 1MW generator set with an annual operation of 1000 hours as an example:

The heat consumption rate of diesel is about 210 g/kWh, and the fuel consumption per 1 MW hour is 210 kg.

The price of diesel is calculated at 6 yuan/kg, with an hourly fuel cost of 1260 yuan.

The substitution rate is 60%, which means saving 126 kg of diesel fuel per hour and saving 756 yuan in costs.

The increase in natural gas consumption is about 130 m ³, resulting in an additional cost of 390 yuan calculated at 3 yuan/m ³.

Net savings: 756-390=366 yuan/hour.

Annual operation of 1000 hours saves 366000 yuan.

The investment in renovating equipment can usually be recovered within one year and will continue to generate profits thereafter.

6.3 Precautions for operation and maintenance

Regularly calibrate sensors, especially exhaust temperature and knock sensors, and check them every 500 hours.

Check the gas valve group: Test the switching action of the dual solenoid valves quarterly to ensure normal operation.

Cleaning mixer: Trace impurities in the gas may deposit on the throttle body, affecting the accuracy of air-fuel ratio control.

Software upgrade: ECU can update control algorithms through USB port. It is recommended to pay attention to the optimized version released by the manufacturer.

Pure diesel mode test: Switch to 100% diesel for at least 30 minutes every month to ensure that the original engine fuel system is in good condition.

Common problems and troubleshooting

7.1 Difficulty starting the engine

Reason: The gas valve is not open (due to power supply failure of the solenoid valve); Mixer stuck; Insufficient natural gas pressure.

Solution: Check the 24V power supply and insurance; Manually test valve action; Confirm that the pipeline pressure is within the range of 3-7 PSI.

7.2 Insufficient power or jitter under high load

Reason: Excessive gas substitution rate leads to lean combustion; The intake temperature is too high; Turbocharger response lags behind.

Solution: View real-time substitution rate and air-fuel ratio curve through touch screen; Contact the manufacturer to adjust the fuel mapping; Check the efficiency of the intercooler.

7.3 Frequent combustible gas alarms

Reason: Trace leakage in gas pipeline; The crankcase blow by gas contains methane; There are other volatile organic compounds in the environment.

Solution: Check all joints with soapy water; Check if the crankcase ventilation pipe is blocked; Calibrate the detector threshold.

7.4 Frequent switching to diesel mode

Reason: A certain safety parameter exceeds the limit (such as high exhaust temperature, detonation, and large vibration).

Solution: Enter the diagnostic interface to view the sensor channel that triggered the last switch, and check the sensor and engine mechanical status in a targeted manner.

7.5 Touch screen no display

Reason: Lack of 24V power supply; Screen backlight aging; The communication line is broken.

Solution: Measure the 24V voltage inside the control cabinet; Check insurance; If powered separately, confirm that the power module output is normal.