Abstract

Obtaining a reliable early warning of a potential risk of explosion or fire event is a major desire for the Petrochemical, Gas, Oil and Fuel Industries in general and especially the offshore platforms.

Unwanted fuel spills of fugitive vapor clouds, migrating along congested pipelines and hot production areas, may accumulate in enclosed areas (traps) or mix with the air to form flammable air fuel mixture that in the presence of an ignition source causes a deflagration to detonation process.

A method and apparatus for detecting flammable and toxic atmospheres are described in the present paper. The method is particularly useful for detecting flammable hydrocarbon vapors in hazardous areas such as: tank farms and storage areas of petrochemicals, engine rooms where leaks of fuels create an explosion and fire hazard, migrating flammable clouds from production/storage! transportation sites.

The method employs remote sensing electro-optical means and uses spectral analysis to detect and identify the presence of flammable vapors, differentiate between paraffin's and aromatics, toxic gases or obscuration conditions, as well as identify the outburst of flames at their ignition time. Various atmospheric conditions (fog, rain, snow) as well as false alarm stimulus (radiation sources, smoke and particles) are discussed and test results on laboratory and field scales up to 100 meters detection range are presented.

The novel optical open path gas detection technology has gained a lot of interest since the late 80's and in recent years, due to technical improvements, installations have been made by British Petroleum (B.P.) Phillips Petroleum, Shell. Typical installations of SAFEYE ™ and SHARPEYE ™ on offshore platforms are presented in this paper.

Introduction

The Petrochemical industry and especially the offshore industry are well aware of the high risk of some of the processes and the safety procedures required to protect the expensive and sometimes irreplaceable equipment and personnel.

In safety applications, gas detection should be used to warn that a hazardous amount of gas may be present in an area. Often it is not important to detect a local leak because it is either too small to threaten safety or may result in flash fires which can be detected and extinguished on time with proper fire hazard management.

Present fire hazard management includes state of the art "Triple IR" optical fire detection technology that provides very fast and accurate fire detection. This technology utilizes the infrared emission spectrum of flames and analyzes it versus background radiation using 3 IR selected channels. The following flame detection survey summarizes the existing technologies employed in flame detection, their limitations and future trends.

U.V FLAME DETECTION

The U.V spectral band because of its short-wave characteristics is absorbed in the surrounding atmosphere by air, smoke, dust, gases and various organic materials. Hence, U.V solar radiation dispersed in the atmosphere, especially at wavelengths shorter than 300 nm (the solar blind spectral band) being absorbed by the surrounding atmosphere, will not create false alarms for the flame detectors using this technology. The U.V spectral signature of the flame has a pattern that can be readily recognized over the background radiation.

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