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Process Plants (process + plant)
Selected AbstractsAssessing risks from threats to process plants: Threat and vulnerability analysisPROCESS SAFETY PROGRESS, Issue 4 2002Paul Baybutt Process security management addresses threats from terrorist and criminal acts against plants that may result in the release of hazardous materials. The risk of such threats must be assessed to determine if existing security measures and safeguards are adequate or need improvement. Risk assessment is the heart of a process security program. Process plants need straight forward and easily applied methods to assess security risks using techniques that can be employed in a variety of situations and at varying levels of detail. This paper describes an approach that accomplishes these objectives. Threat analysis is the first step. It is used to identify the sources and types of threats and their likelihood. The approach described in this paper involves the consideration of motivations and capabilities of adversaries and the rating of facility security factors to develop a threat profile. Once specific threats have been identified, process vulnerability analysis is used to identify threat scenarios, i.e., how threats could be realized. Plants and processes are divided into sectors, and each credible threat within each sector is considered. Vulnerabilities are identified by brainstorming the ways barriers can be penetrated and process containment breached. Checklists are used to guide the brainstorming, and scenario consequences are recorded. Existing security measures and safeguards are listed, and any recommendations for improvements to reduce the likelihood and severity of terrorist and criminal acts are made for consideration by management based on the nature of the threat, process vulnerabilities, possible consequences, and existing security measures and safeguards. Risk rankings are performed as part of the analyses. [source] Isolating the root cause of propagated oscillations in process plantsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2005Xiaoyun Zang Abstract Oscillations are a common type of propagated disturbance, whose sources might be attributable to a number of different phenomena such as poor controller tuning or actuator nonlinearity. A number of data-driven methods have already been proposed to isolate the source loop of nonlinearity induced plant-wide oscillations. Amongst these the bi-amplitude ratio index, correlation dimension, maximal Lyapunov exponent, nonlinearity index and spectral ICA show promise. The propagation of oscillations is first examined in order to gain an understanding of how this might affect the performances of the various techniques. The various methods are then described and their performance on a set of simulation generated data and two industrial case studies are compared. Copyright © 2004 John Wiley & Sons, Ltd. [source] Energy efficiency investments in Kraft pulp mills given uncertain climate policyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2007Anders Ådahl Abstract Energy efficiency measures in pulp mills can potentially reduce the consumption of biofuel, which can instead be exported and used elsewhere. In this paper a methodology is proposed for analysing the robustness of energy efficiency investments in Kraft pulp mills or other industrial process plants equipped with biofuelled combined heat and power units, given uncertain future climate policy. The outlook for biofuel and electricity prices is a key factor for deciding if energy efficiency measures are cost competitive. CO2 emission charges resulting from climate policy are internalized and thus included in electricity and biofuel prices. The proposed methodology includes a price-setting model for biofuel that assumes a constant price ratio between biofuel and electricity in the Nordic countries. Thirteen energy efficiency retrofit measures are analysed for an existing Swedish Kraft pulp mill. Special attention is paid to heat-integrated evaporation using excess process heat. Four possible energy market development paths are considered that reflect different climate policies. Pulp mill energy efficiency investments considered are shown to be robust with respect to uncertain climate policy. Copyright © 2006 John Wiley & Sons, Ltd. [source] Hamiltonian view on process systemsAICHE JOURNAL, Issue 8 2001Katalin M. Hangos The thermodynamic approach of analyzing structural stability of process plants was extended to construct the simple Hamiltonian model of lumped process systems. This type of model enables us to design a nonlinear PD feedback controller for passivation and loop shaping. This approach is applicable for lumped process systems where Kirchhoff convective transport takes place together with the transfer and sources of various types, and the manipulable input variables are the flow rates. Systems with constant mass holdup and uniform pressure in every balance volume satisfy these conditions. General results are shown by simple examples of practical importance: on a bilinear heat exchanger cell and on an isotherm CSTR with nonlinear reaction. [source] What risk should public accept from chemical process facilities?PROCESS SAFETY PROGRESS, Issue 2 2007Ernst Meyer Abstract Major incidents in chemical process plants such as Bhopal have raised the questions of facility, safety, and security by stakeholders and interest groups. How will the facility be perceived as safe given the possible consequences? No one denies that there have been improvements in process safety since Bhopal and many safety regulations have come into effect. The public may still question whether it is safe to live or work near a chemical plant today. This paper discusses the risk that the public should accept under governmental leadership and guidance. Also discussed is how the chemical process industry should ensure risk acceptance criteria compliance and maintenance of compliance throughout the lifetime of a facility. Safety may be enforced by compliance with a pre-defined set of risk acceptance criteria. These criteria may be absolute and tangible, but in some cases are more abstract. Different practices are seen among different countries, states, and regions as well as between different industry segments. This paper discusses the meaning of risk acceptance criteria and how exposed people and regulatory bodies should relate to the criteria. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2007 [source] FINE SCALE VARIABILITY IN SOIL FROST DYNAMICS SURROUNDING CUSHIONS OF THE DOMINANT VASCULAR PLANT SPECIES (AZORELLA SELAGO) ON SUB-ANTARCTIC MARION ISLANDGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2009NATALIE S. HAUSSMANN ABSTRACT. Through changing soil thermal regimes, soil moisture and affecting weathering and erosion processes plants can have an important effect on the physical properties and structure of soils. Such physical soil changes can in turn lead to biological facilitation, such as vegetation-banked terrace formation or differential seedling establishment. We studied the fine scale variability in soil temperature and moisture parameters, specifically focusing on frost cycle characteristics around cushions of the dominant, vascular plant species, Azorella selago, on sub-Antarctic Marion Island. The frost season was characterised by numerous low intensity and very shallow frost cycles. Soils on eastern cushion sides were found to have lower mean and maximum temperatures in winterthan soils on western cushion sides. In addition, lower variability in temperature was found on eastern cushion sides in winterthan on western cushion sides, probably as a result of higher wind speeds on western cushion sides and/or eastern, lee-side snow accumulation. Despite the mild frost climate, extensive frost heave occurred in the study area, indicating that needle ice forms at temperatures above ,2°C. Our results demonstrate the effectiveness of frost pull as a heave mechanism under shallow frost conditions. The results highlight the importance of Azorella cushions in modifying site microclimates and of understanding the consequences of these modifications, such as potentially providing microhabitats. Such potential microhabitats are particularly important in light of current climate change trends on the island, as continued warming and drying will undoubtedly increase the need for thermal and moisture refugia. [source] | |||||||||||||