Method of identifying and stopping an electronically controlled diesel engine in RUNAWAY MODE

A diesel engine is said to be in runaway mode when it runs out of control using an external fuel source and the operator cannot shut down the engine using conventional methods. During runaway, the engine damage can range from minor to catastrophic and this can cause enormous damage to the environment due to a lack of emissions control under these circumstances. In addition, an organization can incur financial losses due to loss of an entire engine and/or engine components.

In engine applications such as power generation in an oil refinery, oil mist can enter the intake stream of the engine and cause an engine runaway. In some OHW (Off-Highway) and CV applications, the oil separator is connected to the intake system to have closed-loop crankcase breathing system where in the engine oil may enter the combustion chamber through intake and the engine enters runaway mode. In scenarios where the turbocharger piston rings fail due to high pressure difference, the oil used for lubrication of the turbocharger bearings enters the intake through the turbo compressor, resulting in engine runaway until the oil in the crankcase sump is completely consumed.

In literature, one of the methods to detect a runaway condition is to check if the engine speed reaches unsafe values. It is also possible to detect a runaway condition based on current acceleration time and compare the same with the safe thresholds. Both these methods are not fast enough for runaway detection as they need to wait for a threshold violation to determine a runaway mode. In this paper, a method is proposed to improve the response time of the runaway detection system in electronically controlled engine applications.

The intention of the proposed method is to ensure very fast detection of the runaway condition and shutting off the engine using electronically- controlled actuators, thereby saving the engine and engine components.

Safety in diesel engine control is given the highest priority to avoid both damage to equipment as well as death or injury to operating personnel. The need is for precise control of the diesel fuel and intake air to ensure that the energy released from the fuel is safe and identify when the energy released is potentially unsafe.

A vast number of diesel engines are used in the petrochemical and oil and gas industry for day-to-day operations. In such industries, there is a possibility of leak of flammable hydrocarbons and this will pose a serious hazard to both the diesel engine and personnel. A diesel engine runaway can be described as a situation where the engine runs out of control from an external fuel source (such as oil mist in the charge air) and the engine cannot be shut down using conventional methods (i.e. turning off the engine ignition switch or fuel system, injection cut-off from the ECU, disengaging engine load, etc). Consequences of engine runaway can range from minor engine damage to engine explosion, causing catastrophic damage to the equipment and surrounding facilities and/or death or injuries to personnel.