This position paper describes how gas engines are influenced by the quality of the gaseous fuel provided. This topic is becoming increasingly important as highly fluctuating renewable energy resources call for quick reacting and reliable back-up power often provided by gas engines.
Important aspects of the quality of a gas, in addition to the heating value and the Wobbe Index, are: the composition of the combustibles which influences the combustion behaviour and knocking characteristics, the rate of change of the gas composition with time, and the concentration of impurities, for example sulphur. The knock characteristics of a gaseous fuel can be calculated for a given composition and the calculated Methane Number (MN) indicates the resistance of the given fuel to end gas knock. The Methane Number is comparable to the octane number for liquid fuels, which is typically used with gasoline fuels for passenger cars.
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In 2018, the industry experienced a series of marine fuel incidents impacting the operation of more than 100 vessels. The specialists of CIMAC WG7 Fuels have prepared a statement .. more
The guideline aims to understand the issue of cold corrosion which has been a regular occurrence with operators of large two-stroke marine engines due to engine operation at low loads. It intends .. more
The CIMAC Position Paper ‘Gas Engine Aftertreatement Systems’ has been compiled by the CIMAC WG17 'Gas Engines' members and provides an overview regarding the exhaust aftertreatment .. more
The CIMAC Working Group 7 Fuels has prepared and issued a guideline to provide answers to the questions that may arise with the publication of ISO 8217:2017, the latest specification of .. more
This guideline follows on from the CIMAC WG7 guideline No 09:2014  which set out the differences between the ISO 4259 approach and that adopted under MARPOL Annex VI in respect of fuel .. more
The CIMAC Working Group 7 Fuels has prepared and issued a guideline on filtration of residual fuels. Traditionally, filters have been considered a safeguard for marine engines, however, a more .. more
This position paper describes how gas engines are influenced by the quality of the gaseous fuel provided. This topic is becoming increasingly important as highly fluctuating renewable energy .. more
New 0.10% sulphur (S) marine fuels recently introduced in the market offer an economically attractive alternative to conventional distillate fuels such as DMA. Before purchasing a new fuel product, .. more
With the introduction of MARPOL Annex VI, the sulphur content of a particular fuel oil is now often the primary factor in assessing whether or not that fuel oil is acceptable for intended use. .. more
The purpose of this paper is to consider the various types of fuel, and combinations of fuels, that may be used by marine vessels through to 2025, and then to discuss the potential impacts that .. more
Unburned Methane emissions from gas engines are of concern because of their contribution on global warming. Formaldehyde – a toxic interstage product of the Methane oxidation process – .. more
Over the last few years gas-fuelled engines have become more popular also in the marine industry both for on-board power generation and propulsion duties. Whereas the use of gas-fuelled marine .. more
Crankcase explosion is caused due to the overheating of one of the cylinders in the main machinery space. The consequences of the explosion is severe and it affects the working of other engines. .. more
In the current absence of an officially accepted specification for marine fuel containing more than 0.1% v/v biodiesel, this CIMAC publication provides background information and guidance to .. more
Discussions have started up at IMO about the need and potential for restricting black carbon (BC) emissions in the Arctic region caused by international shipping.
Especially regarding switch of .. more
This document has been prepared to advise the crew, users, vessel owners, charterers, crew, fuel and lubricant suppliers, equipment manufacturers, and classification societies about the fuel .. more
This document intends to collect information about the situations experienced where the Ignition and Combustion properties of the fuel are suspected of having influenced negatively on the .. more
On 10 October 2008, the IMO Marine Environment Protection Committee at its 58th session, by Resolution MEPC.177(58), has adopted amendments to the Technical Code on Control of Emission of Nitrogen .. more
Since many years discussions are ongoing between CIMAC WG2 and the IACS MP with regard to the use of Alu and/or Alu-alloys in engine rooms of category "A".
Today, mainly for 4-stroke medium and .. more
The presently available requirements with regard to the tightness of pipe connections for flammable, highly inflammable and potentially explosive media and fluids are clearly requesting tightness. .. more
This document provides the background information on black carbon emissions from large marine and stationary diesel engines. It discusses about the need and potential for restricting black carbon .. more
Recent emission regulations and the trend towards utilization of waste gases and renewable fuels have generated a rising interest in using gas engines in applications where Diesel/HFO engines were .. more
Current commercial residual fuel specifications cannot reliably predict the ignition and combustion characteristics of a fuel due to lack of a suitable test parameter. They cannot therefore protect .. more
This document briefly explains the importance of technique specific emission regulations. Some general features of the stationary engine plant are presented, such as:
engine types & fuel .. more
Ambient conditions depend on the geographical location and may vary with time of the year. The performance of an engine is influenced by the ambient conditions. The most important ambient .. more
This paper discusses some of the issues associated with ammonia content of gas engine fuel. It explains how ammonia is a strong driver in NOx production in the engine opeartion,reasons for ammonia .. more
LNG, liquefied natural gas, is natural gas cooled down to about –161 °C at atmospheric pressure and transported as a liquid. It is now rapidly becoming a widely used engine fuel in .. more
Control of Emissions of Air pollution from Locomotive Engines and Marine compression-ignition engines less then 30 litres per cylinder.
This publication discusses the following issues: .. more
Subject: Implementation of new or revised UR
On the occasion of the last CIMAC WG2 meeting at Vaasa in April 2005 we ocassionally learned that some UR have been revised and .. more
Subject: Delivery of EIAPP Certificates
Since that moment when the new IMO regulations regarding NOx came into force claims from engine builders increased. The engine builders .. more
Subject: Attendance at Type Approval Tests (TAT)
Background: Within the last years quite some experience was gained during Type Approval Tests. We have realized that Class surveyors well attended .. more
Use of low sulphur diesel fuels in coastal waters.
CARB / EPA propose that Ocean going ships must use only distillate fuels (diesel oil) with a low sulphur content and a low content of aromatic .. more