Air-fuel ratio control system and control method for biogas internal combustion generator set

Abstract

The invention discloses a system for controlling the air-fuel ratio of a biogas internal combustion generating set and a control method of the system. The system comprises an air inlet pipeline and a biogas inlet pipeline both connected with an inlet of a mixer. A fuel gas valve is arranged at the connecting position of the biogas inlet pipeline and the mixer, and an outlet of the mixer is connected with the internal combustion generating set through a throttle valve. A methane concentration sensor is arranged in the biogas inlet pipeline and used for transmitting detected methane concentration information in biogas to a controller. An oxygen sensor is arranged in an exhaust pipe of an internal combustion generator and used for feeding back the measured oxygen content of tail gas in the exhaust pipe to the controller. The actual air-fuel ratio is acquired by the controller according to the received oxygen content of the tail gas, and compared with a given air-fuel ratio, and therefore the air-fuel ratio difference value is acquired. The controller is used for controlling the opening degree of the fuel gas valve according to the air-fuel ratio difference value, then the opening degree of the fuel gas valve is corrected according to the acquired methane concentration information, and therefore the aim of precisely controlling the air-fuel ratio is achieved.

Description

technical field [0001] The invention belongs to the fields of environmental protection and energy, and in particular relates to an air-fuel ratio control system and a control method for a biogas internal combustion generator set. Background technique [0002] In today's energy shortage and increasingly serious environmental pollution, biogas has become a new energy source with great development potential because of its outstanding characteristics such as renewable, large resources, wide distribution, and low pollution. The effective combustion of biogas can greatly improve the efficiency of generating units, which is of great significance for saving energy and reducing pollutant gas emissions. [0003] Compared with combustible gases such as natural gas, biogas has the problems of low calorific value and unstable content of combustible gas components, which can easily make starting difficult for biogas internal combustion generator sets, unstable speed, insufficient power, e...

AI Technical Summary

Problems solved by technology

However, biogas is different from natural gas. The composition of biogas is affected by the fermentation conditions, and the concentration of combustible gas fluctuates greatly, which cannot be ignored.

The calorific value of biogas is low, and it is easy to cause difficulty in starting and unstable speed

[0005] Moreover, the patent No. 201410057911 is an automatic air-fuel ratio control system for a gas engine. This control system can control the air-fuel ratio to an ideal state through the feedback of an oxygen sensor, but there is a control lag problem, and the response is not timely, and it does not take into account the effect of cylinder temperature on the combustion state. It is difficult to achieve the purpose of precisely controlling the air-fuel ratio

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