RELATED REGULATION OF BIOGAS SUPPLIES AND METHANE IN A GAS ENGINE

Abstract

The results of experimental researches were received on a gas-electric installation with a rated power of 30 kW at 1500 rpm. The spark-ignited petrol drive engine (8-cylinder, 100 mm cylinder diameter, 88 mm stroke) was converted to a pure gas one. The compression ratio of 8.5 did not change. The gas fuel supply system consists of a supply line and an emergency shut-off circuit. The natural gas supply line was connected to the domestic main line through a special gas distributor. On the basis of HEINZMANN components, a system for dosing mixed gas fuel was developed, which, through a microprocessor control unit and an actuator, acted on the throttle valve of the gas mixer. In experimental researches, the composite fuel was a model gas – a mixture of natural and carbon dioxide gases, which was prepared in a zero pressure reducer before the gas mixer. With an increase in the volume fraction of carbon dioxide in the model gas by more than 34 %, a deterioration of the combustion process was observed in the steady state. In the article, based on the analysis of the experimental results of the operation of a piston gas engine on a model gas, an algorithm for the use of associated automatic control of biogas and methane feeds is substantiated. The transition from quantitative to qualitative regulation of the gas-air mixture has been substantiated. To do this, it is necessary to create two automatic control loops for the supply of air and a mixture of natural gas, which are interconnected through an external load. With the developed algorithm, as the load increases, the supply of natural gas increases, and the supply of biogas decreases. With an increase in the load of 75 % or more, a more intensive enrichment of the fuel mixture with natural gas occurs than at low and medium loads. The proposed algorithm for regulating the fuel mixture can be implemented using electromagnetic gas injectors for dosing the components of the composite fuel. Signals from sensors for oxygen and methane content in exhaust gases were selected as corrective links for the coupled control algorithm. Recommendations on the choice of tuning modes for oxygen and methane sensors have been developed.