Integrating switchgear breakers and contactors into a safety instrumented function

In the process industries, electrical circuit breakers are tripped for a variety of reasons including hazard prevention and mitigation. This paper will discuss the application of tripping electrical breakers for process safety reasons. It often occurs that a risk assessment study has determined the need to include the shutdown of a large electric motor as part of a safety instrumented function (SIF). In the process industries, it is common practice to control and protect large horsepower motors (typically 2000 HP and above), with medium-voltage switchgear breakers. Safety instrumented functions that include electric motors utilizing medium-voltage switchgear for tripping have unique final element subsystems, which require specialized knowledge in order to implement correctly. This paper will discuss the design considerations for integrating medium-voltage switchgear used for shutdown of an electric motor into a safety instrumented function. First, an overview of typical low and medium-voltage electrical equipment used for controlling and protecting electric motors will be discussed. Next, a review of generic sourced failure data for medium-voltage switchgear breakers will be presented. Focus will be on the taxonomy used to classify different breaker types and the relevant failure modes and effects used for quantifying performance. Next, specific SIF design details for tripping medium-voltage switchgear breakers will be analyzed in the context of achieving a certain integrity level. Parameters to be considered include hardware fault tolerance requirements, voting, available diagnostics, energize vs. de-energize to trip shutdown circuits, certified equipment vs. proven-in-use, and alternate means of shutdown (including manual intervention and protective relaying). This paper will also analyze the common electrical equipment that is shared among potential protection layers used to trip the same breaker, and determine how much credit can be taken considering common cause failure. Finally, inspection, test, and preventive maintenance (ITPM) of medium-voltage switchgear will be discussed as a means for maintaining the electrical equipment in the “as good as new” condition.     

IMPROVING IRRIGATION WATER MANAGEMENT IN THE INDUS BASIN1

ABSTRACT: Over half of the water delivered from the canal system to the watercourses managed by the farmers is not made available to the farmers' crops in Pakistan. Most of this water loss is due to loss of water through the banks of the watercourses. Lack of maintaining these banks and lack of cleaning the watercourse is a result of inadequate organization of the 10 to 150 farmers who use the watercourse, and a deficiency of knowledge concerning the amount of their water which is being lost. Various methods of watercourse improvement have been evaluated including concrete and masonry linings and simple earthen improvements of the ditches with concrete control structures, junctions, and turnouts. With the cost of labor low in Pakistan, the earthen improvements with concrete structures appear to be the best investment. Farm water management improvement programs have been implemented in most of the provinces which include this type of watercourse improvement, land leveling and advice to the farmers on how and when to irrigate his crops to optimize his production. The rate at which personnel can be trained to help the farmers implement these improved water management practices is limiting the rate of implementation.     

Policies and regulations for Brazil’s artisanal gold mining sector: analysis and recommendations

In Brazil, artisanal and small-scale gold mining (ASGM) produces in the range of 6 tonnes of gold (Au) per annum, and employs approximately 200,000 people. Most of this mining activity is in the Amazon region, where miners have been extracting gold for more than 40 years. In the Tapajos River Basin, assessments indicate that around 99% of miners operate without the environmental and mining permits required by law. This is a result of a combination of unrealistic or lack of proper policies and regulations, lack of political will, lack of infra-structure to enforce the existing regulations and lack of incentives to miners to comply with legal requirements.In this article, we analyze a group of 20 laws, decrees and resolutions in Brazil, focusing on how idiosyncrasies in these regulations reveal gaps between policy and reality in ASGM areas. Artisanal miners operate in vast and remote areas and the government lacks the resources (personnel, vehicles, information and materials) to enforce the laws. Our analysis emphasizes the need for creating new government commitments and identifying priority areas where government agents can focus their efforts.There is no single solution for the environmental, health, technical and socio-economic problems associated with ASGM. However, a realistic approach should consider improving the level of education of miners, creating government programs to provide technical assistance in the field, simplifying administrative procedures and ensuring adequate measures for enforcement.     

Toward an inherently safer design and operation of batch and semi-batch processes: The N-oxidation of alkylpyridines

This work shows an application of inherent safety principles to a reaction widely used in the pharmaceutical industry. More specifically, it incorporates the teachings of Trevor Kletz into the design of an inherently safer process for the N-oxidation of alkylpyridines. This reaction is of interest because of the hazards resulting from the undesired, gas-generating decomposition of hydrogen peroxide, the oxidizing agent. The generation of oxygen, combined with the flammability of the alkylpyridines, represents a serious fire and explosion hazard for this process. The purpose of this paper is to demonstrate how an inherently safer process can be potentially achieved by designing improved reactors and by assessing conditions that reduce or eliminate the hazards. Furthermore, it is shown that such improvement in safety increases the efficiency of the process and results in a cost reduction.     

Management of water resources of the Nile Basin

SUMMARY

A water crisis is looming in the Nile Basin in the near future due to higher population growth rates, greater affluence, and higher demand for water by agriculture and industry. There is no basin-wide agreement among the ten Nile Basin states and the existing rules of international water management are complicated and are not equipped to handle any future water conflicts in the Nile Basin. This paper reviews the existing water sharing arrangements among the Nile Basin countries, examines areas of potential conflict over future water use, and suggests possible areas of cooperation that will ensure equitable use of the Nile waters. The paper concludes by (1) appealing for formulation of good water development policies to deal with growing water needs such as water quality protection, efficiency of water delivery and efficiency of water use; and (2) calling for human resources development and technology transfers that are critical for good management and efficient use of the water resources of the Nile.     

Towards improved socio-economic assessments of ocean acidification’s impacts

Ocean acidification is increasingly recognized as a component of global change that could have a wide range of impacts on marine organisms, the ecosystems they live in, and the goods and services they provide humankind. Assessment of these potential socio-economic impacts requires integrated efforts between biologists, chemists, oceanographers, economists and social scientists. But because ocean acidification is a new research area, significant knowledge gaps are preventing economists from estimating its welfare impacts. For instance, economic data on the impact of ocean acidification on significant markets such as fisheries, aquaculture and tourism are very limited (if not non-existent), and non-market valuation studies on this topic are not yet available. Our paper summarizes the current understanding of future OA impacts and sets out what further information is required for economists to assess socio-economic impacts of ocean acidification. Our aim is to provide clear directions for multidisciplinary collaborative research.     

Calibrate failure-based risk assessments to take into account the type of chemical processed in equipment

Currently, failure-based risk assessments in the process industry do not empirically take into account the type of chemicals processed in equipment, mainly because chemical-specific failure rate data barely exist. This paper suggests a methodology to calibrate failure-based risk assessment predicated on the chemical being processed in equipment. The methodology uses a data mining tool known as the association rule. Specifically, the lift association rule is utilized (the Lift Methodology). By extracting equipment failure information from incident databases based on the chemical involved in the process, the Lift Methodology leads to more accurate equipment-related risk assessment.     

Comparing the impacts of mitigation and non-mitigation on mountain pine beetle populations

Mountain pine beetles, Dendroctonus ponderosae (Hopkins) attack and can ultimately kill individuals and groups of pine trees, specifically lodgepole pine (Pinus contorta Dougl. ex. Loud var. latifolia Engl.). In British Columbia, beetle attack has increased from 164 000 ha in 1999 to over 13 million ha in 2008. Mitigation efforts can play a key role in addressing the impact beetle infestations can have on the forested landscape. In this research, the impact of mitigation on a mountain pine beetle infestation is examined within a network of 28 research plots where sanitation harvesting was completed (10 mitigated plots) and not completed (18 unmitigated plots). Three forest stand level modelling scenarios which predict the number of attacked trees, based on current infestation within the plots, were utilized to compare the differences between mitigated and non-mitigated plots. In the first scenario in the non-mitigated plots, 125 trees were infested after 10 years, while in the mitigated plots no trees were infested in the same time period. The second scenario indicates the level of mitigation required to suppress beetle infestations where the proportion of mitigated trees was calculated for each plot by counting the residual attack and the number of mitigated trees. The average mitigation rate over all plots of 43% (range 0–100%) is not sufficient to provide control. In the non-mitigated plots, the average population expansion rate was 5 (range of 0–18) which requires a detection accuracy of 74% to reliably detect infestation. The third scenario estimated the length of time required for ongoing detection, monitoring, and mitigation to bring an infestation under control. If mitigation efforts were maintained at the current rate of 43%, the beetle population would not be adequately controlled. However, when aided by continued detection and monitoring of attacked trees, mitigation rates greater than 50% are sufficient to control infestations, especially with persistent implementation, aided by continued detection and monitoring of infested trees.