Structured packings for use in oxygen service: Flammability considerations

Metallic structured packings have found increasing use in the cryogenic distillation of air. An experimental program was performed to test the flammability of selected metal packings under simulated high oxygen concentration operating conditions. Aluminum flammability in gaseous oxygen has been shown to be very dependent upon argon dilution, and in the presence of liquid oxygen, strong energy releases have been observed. Brass packing exhibited an unexpectedly high relative flammability whereas copper has been found to be non-flammable in all tested oxygen purities. These findings suggest the use of copper structured packing in higher purity GOX/LOX regions of an air separation distillation column and aluminum structured packing in the remainder of the column.     

Spontaneous fires in insulation

Combustible liquids may self-heat in porous insulation yielding smoldering or flaming combustion. In Part I the problem is reviewed and practical measures discussed. Using two-inch cubes of insulation and a standardized procedure, Spontaneous Ignition Temperatures (SITs) ranging from 55-184 C are reported for a series of combustible liquids. The application of a self-heating parameter Z = (AIT)/(AIT-FP), where AIT is autoignition temperature and FP is closed cup flash-point (both in Celsius), is examined. The “Z” parameter gives some indication of materials that will self-heat and those that will evaporate. For Z > 1.61 ignition occurred for all the liquids tested. Evaporation usually occurred for materials with Z < 1.35. It was found that some water-reactive or peroxide-forming materials can ignite where only evaporation would be predicted from Z value considerations. An important example of a water-reactive material is ethylene oxide (EO); the importance of EO insulation fires is that under certain conditions explosive decomposition of EO contained in the equipment can be initiated. It was previously determined that ethylene oxide reacts in porous, refractory insulations forming low molecular weight polyethylene glycols. The formation rate depends on temperature and the type and condition (particularly water content) of the insulation. Unlike EO the glycols have low volatility and may accumulate over time to several times the mass of some insulations. Under certain conditions the glycols can ignite spontaneously. In Part II experiments carried out to examine this phenomenon are discussed. Where process temperatures are above the SIT (but below the AIT), cellular glass insulation will minimize the risk of insulation fires. One disadvantage, especially for thermally unstable materials such as EO, is that cellular glass has poor fire endurance properties. The use of a realistic fire endurance test to specify insulation thickness and additional measures such as stainless steel jackets are described. Alternatives to the use of cellular glass are discussed. When selecting an insulation system, it should be determined whether an insulation fire might occur and the loss potential from such an event should be evaluated.     

BOOK REVIEWS

Dynamics and Conflict in Regional Structura1 Change—Essay in Honor of Walter Isard Volume 2 Practical Methods of Regional Science and Empirical Applications—Selected Papers of Walter Isard, Volume 2 Department of Economics Loughborough University Export Promotion Strategies—Theory and Evidence from Developing Countries Commonwealth Secretariat Export Market Development Division Human Development Report 1990 for the United Nations Development Programme (UNDP) (New York and Oxford: University of Nottingham The World Bank and the Environment—First Annual Report Fiscal 1990, The World Bank (New York: The World Bank, 1990 London Environmental Economics Centre University College London The European Communities' Single Market: The Challenge of 1992 for Sub-Saharan Africa Loughborough University     

An overview of exposures and exposure control in the ethylene oxide producer and ethoxylation industries

This paper presents the results of an industry survey that was sponsored by the Ethylene Oxide Industry Council (EOIC). The EOIC operates as a special program of the Chemical Manufacturers Association. The members of EOIC account for over 85 percent of domestic production of EtO and cover a broad range of EtO users, including ethoxylators and sterilizers. The survey was done to collect current information in anticipation of responding to a proposed OSHA rulemaking for a short-term exposure limit for EtO. Specifically, the study was designed to collect information on the following:

• 1. History of the establishment of company EtO exposure guidelines.
• 2. Current EtO workplace exposure monitoring practices, capabilities and methods.
• 3. Current workplace exposure levels: Eight hour and short-term.
• 4. Engineering control, respirator, and ancillary costs for compliance with the 1.0 Permissible Exposure Limit (PEL) and projected costs for compliance with a 5.0 ppm or 10.0 ppm Short–term Exposure Limit (STEL).

     

IMPERFECT INFORMATION AND THE CHOICE BETWEEN COLLUSION AND HORIZONTAL MERGER

If the payoff obtained by the parties of an agreement depends on the values set for variables the value of which cannot be described precisely or monitored accurately, then the first best outcome may not be achieved. It is shown here that in some cases a second best long term agreement gives the parties a higher payoff, in other cases a short term arrangement is preferred. The interpretation of this result given in the paper is that when a long term contract is preferable, then firms are unable to commit themselves to it through a collusive agreement, and they will try to merge. Vice versa, no need to integrate arises when the preferred second best agreement is the short term one. The last section provides an example, where advertisement effort is non-contractible, while prices are.     

TRAINING AND LABOUR MARKET SEGMENTATION

A two period model of the training decision is analysed using a human capital approach. The segmented labour market model where training opportunities distinguish entrants is compared with a competitive structure with homogeneous entrants. The main conclusions in the paper are the clear effects of training wages and the different effects in the two market structures of both wages and employment prospects in the unskilled market on training.     

Ultimate capacity of blast loaded structures common to chemical plants

There has been a great deal of investment in development of design criteria and design and construction of heavily reinforced, blast-resistant control rooms. This remains the best option for protective construction against severe blast loading experienced close in to a vapor cloud or other explosion hazard. However, most structures encountered at chemical plants and contemplated for future construction are conventional steel frame, metal clad buildings. In this paper we look closely at the response of such buildings to explosion loads and their ability to undergo large deformations without structural failure. The types of structural elements evaluated include metal decking of various gauge and shape along with a variety of girt and purlin sections. Building frames or bents are also evaluated, although the date base for these is much more limited. The work is based on observations made during investigations of large explosion accidents along with analytical predictions and test measurements. To conclude, we offer specific design criteria and connection recommendations for enhancing the overall strength of a building through the use of conventional components in unconventional construction.     

Sharing versus collaborative economy: how to align ICT developments and the SDGs in tourism?

Great hopes have been placed in the sharing economy to provide a new business model based on peer-to-peer (P2P) exchanges of underutilized assets. As a model, the sharing economy has been expected to make significant contributions to sustainability, providing new opportunities for entrepreneurship, more sustainable use of resources, and consumer co-operation in tight economic networks. However, in recent years, digital platforms have turned into the most important actors in the global sharing economy, turning global corporations, such as AirBnB, Booking, or TripAdvisor into intermediaries controlling and profiting from most transactions. Focused on accommodation, this paper conceptualizes the sharing economy in comparison to the wider collaborative economy, and discusses its social, economic, environmental, and political impacts in comparison to the sustainable development goals. It concludes that the sharing economy has great potential to make very significant contributions to sustainability, though the model is increasingly being replaced by the collaborative economy, which performs as an extension and acceleration of neoliberal economic practices.     

Roadmap for interactive exploration of sustainable development opportunities: The use of simple instruments in the complex setting of bottom-up processes in rural areas

Before embarking on the development of rural areas or regions it seems necessary to answer the following key questions: what goals of the parties involved can be realized, and where, when and how? To tackle these questions we have developed a ‘roadmap’, as part of an overall sustainable development procedure for physical planning and spatial management in rural areas. The roadmap is a tool for the process manager and the people involved. It helps to find the way in the exploration of the potential social, economic and ecological benefits of developing the area or region. The purpose of using the roadmap is to alleviate doubts about the advantages of cooperating in pursuit of sustainable development. A back-casting approach is applied to create appealing visions of the future and visualize mutual opportunities worth implementing. In this article we first describe the need for this new roadmap. We then describe its use, step by step and in some detail. An example of the exploration process is described and the strengths and weaknesses of the roadmap are discussed.     

The deterrent impact of police: An examination of a locally provided public service

This paper develops and empirically tests a model of crime deterrence in an urban area. There are two important departures from past efforts to study the impact of criminal sanctions. The first is that the provision of sanctions from the local public sector is modeled; this is accomplished by specifying the distributional goals of local government and by specifying the production of safety. The second departure is that actual crime and reported crime are differentiated theoretically and in the empirical work. An empirical test of the model, using a unique neighborhood data set, shows that police deter crime significantly; however, this deterrent impact cannot be demonstrated without the distinction between actual and reported crime.