Fuel Gas Supply Control for Gas Engine Abnormal Combustion
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Solution Overview
Problem
Conventional gas engine fuel gas supply systems face challenges in preventing abnormal combustion such as self-ignition, especially when using low-calorie gases, due to fluctuations in fuel gas concentration, which can lead to safety risks and require complex control structures and large compressors.
Innovation Solution
A fuel gas supply method and apparatus that maintain a constant flow rate ratio between the supercharger-side and cylinder-side gas supply passages, adjusting fuel gas flow rates using valves to keep the gas concentration below the flammable limit without a concentration meter, ensuring the engine's output remains constant and safe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel gas is supplied to the supply air passage upstream of the supercharger, then the fuel gas can be mixed with air before compression, but the gas concentration may exceed the lower flammable limit causing abnormal combustion such as self ignition
Solution Approach 1:
The invention controls the flow rate of fuel gas supplied to the supercharger-side gas supply passage by changing the parameter of gas concentration to maintain it below the lower flammable limit, thereby preventing abnormal combustion while enabling fuel gas supply upstream of the supercharger
2Productivity
If a large capacity gas compressor is used to compress low calorific gas, then sufficient flow rate can be achieved, but the compressor size and capacity increase
Solution Approach 1:
The invention segments the fuel gas supply into two separate paths: one path supplies fuel gas to the supercharger-side gas supply passage for mixing with air before compression, and the other path supplies fuel gas directly to cylinders via the gas compressor. This segmentation allows the compressor to handle only the necessary flow rate, reducing its size while maintaining sufficient total fuel gas supply
3Productivity
If fuel gas adjusting valves are provided just before each cylinder to equalize air-fuel ratio, then work efficiency improves, but the system complexity increases
Solution Approach 1:
The invention merges the fuel gas supply control for the supercharger-side passage and cylinder-side passages under a single gas amount controller that manages multiple adjusting valves. This unified control approach maintains equalized air-fuel ratios for efficient combustion while reducing overall system complexity compared to completely independent control systems
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 approach prevents abnormal combustion by maintaining a stable gas concentration, reducing the risk of self-ignition and explosion, simplifying the control system, and allowing for a more compact compressor design, even with low-calorie fuels like Coal Mine Methane.
Implementation Method 1
a gas compressor for compressing the fuel gas
Implementation Method 2
one for supplying fuel gas to a supply air passage located upstream of the supercharger before pressurizing the fuel gas by a gas compressor
Data Source
Figure 1
Figure 2A~3
Figure 4
AI summary
In an gas engine provided with a gas supply pipe 35 branching into a supercharger-side gas supply pipe 33 and a cylinder-side gas supply pipe 37, a supercharger-side gas adjusting valve 43 and a cylinder-side gas adjusting valve 45 for controlling flow rates of passages, when gas concentration of the fuel gas changes, the cylinder-side gas adjusting valve 45 is controlled first to keep the output of the gas engine constant and then the supercharger-side gas adjusting valve 43 is controlled to achieve the fuel gas flow rate Q1 based on the constant flow ratio by means of a gas supply controller 63, while maintaining the flow rate ratio Q1/Q2 at a constant value where Q1 is a fuel gas flow rate in the supercharger-side gas supply pipe 33 and Q2 is a fuel gas flow rate in the cylinder-side gas supply pipe 37