Dual Fuel Engine Surplus Gas Management
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Solution Overview
Problem
Dual fuel compression ignition engines face challenges in managing surplus pressurized natural gas, which can lead to undesirable venting of methane to the atmosphere, especially during engine shutdown and changes in operational load conditions.
Innovation Solution
A dual fuel common rail system with a gaseous fuel common rail and a liquid fuel common rail, featuring a surplus gas system with an accumulator and a pressure reduction valve, allows for the reduction of gaseous fuel pressure without venting, by transferring gas to an accumulator during surplus conditions and controlling fuel injection to prevent methane slip and optimize combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large charge of natural gas is stored in the tank, then the engine has sufficient fuel for operation, but the tank builds up pressure and vents excess evaporated gas to atmosphere
Solution Approach 1:
A surplus gas system acts as an intermediary between the natural gas storage tank and the engine intake. This system captures evaporated gas that would otherwise be vented and redirects it to the engine for combustion, eliminating harmful methane emissions while preserving fuel storage capacity
Solution Approach 2:
The system changes the state of surplus natural gas from a harmful vented emission to a useful fuel source by controlling its redirection to the engine intake manifold. Parameters such as gas flow rate, pressure, and timing are adjusted to optimize combustion while preventing intake manifold ignition
2Object-generated harmful factors
If evaporated natural gas is routed to the intake manifold, then venting is avoided, but the air/gas mixture may ignite in the intake manifold
Solution Approach 1:
The electronic controller continuously monitors engine operating conditions and dynamically controls the surplus gas supply valve based on real-time feedback. This ensures gas is only routed to the intake manifold when combustion conditions are favorable, preventing premature ignition while maximizing venting avoidance
Solution Approach 2:
The system dynamically adjusts the flow of evaporated gas to the intake manifold based on varying engine operating conditions. The surplus gas supply valve responds to changing load, speed, and combustion conditions to optimize safety and efficiency
3Object-affected harmful factors
If a restriction orifice is used to limit gas flow, then intake manifold combustion is prevented, but the flow rate is limited and may not be sufficient for complete gas utilization
Solution Approach 1:
The system replaces the passive mechanical restriction orifice with an electronically controlled valve system. This substitution allows dynamic adjustment of gas flow rates based on real-time engine conditions, optimizing both safety and gas utilization efficiency without the fixed limitations of a mechanical orifice
4Stress or pressure
If the pressure reduction valve is opened to reduce gaseous fuel pressure, then pressure control is achieved, but gas flows to the accumulator increasing surplus gas storage
Solution Approach 1:
The pressure reduction valve is opened in advance of potential venting conditions to proactively manage pressure buildup. By reducing pressure early and directing gas to the accumulator, the system prevents tank pressure from reaching venting thresholds while efficiently utilizing gas before it becomes surplus
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces methane venting to the atmosphere, allowing for efficient management of surplus gas and maintaining engine performance by burning surplus gas when conditions are favorable, thus minimizing greenhouse gas emissions and ensuring operational efficiency.
Implementation Method 1
A dual fuel common rail system with a gaseous fuel common rail and a liquid fuel common rail, featuring a surplus gas system with an accumulator and a pressure reduction valve, allows for the reduction of gaseous fuel pressure without venting, by transferring gas to an accumulator during surplus conditions
Implementation Method 2
A pressure reduction valve has a first configuration that fluidly connects the gaseous fuel common rail to the surplus gas system, and a second configuration that fluidly blocks the gaseous fuel common rail to the surplus gas system
Implementation Method 3
a gaseous fuel common rail fluidly connected to a plurality of fuel injectors that are each positioned for direct injection into one engine cylinder
Data Source
AI summary
A compression ignition dual fuel engine supplies natural gas fuel and liquid diesel fuel to each engine cylinder from a common fuel injector. Each fuel injector is fluidly connected to both a liquid fuel common rail and a gaseous fuel common rail. The engine includes a surplus gas system for capturing surplus gas, such as evaporated gas from the gaseous fuel supply and pressure control system, or left over pressurized natural gas produced by engine shut down. Rather than being vented to atmosphere, the surplus gas can be burned in the engine when operating conditions present burn opportunities.