The Inventory Phase

The various steps of the inventory phase are shown in Fig. 15.2. The aim of the inventory phase is to comprehensively identify and quantify flows between the technical product system and the environment, i.e., emissions and resources. An example of an inventory of a product system is shown in Fig. 15.3 and Table 15.1. 

The inventory tasks is to collect environmentally important information about relevant processes involved in the product system. Inventory collects information about unit processes at first and subsequently, an inventory of inputs and outputs of the system and its surroundings is carried out. The goal is the identification and quantification of all elementary flows associated with product system. Inventory analysis is the nature of the technical implementation of LCA studies. It is an essential part of a study, has high demands for data availability, practical experience in modelling product systems and, in the case of using database tools, it is necessary to master them perfectly and to understand their function [46]. The inventory phase principle is data collection that is used to quantify values of the elementary flows. This phase represents a major practical part of the LCA study, time consuming and with demands for data availability and author s experience with modelling product system studies [47],... 

In the inventory phase the boundaries between the inputs from and the outputs to the environmental system and the boundaries between the product system under study and other product systems are specified. In this stage three elements may be distinguished the definition of the processes of the product system the specification of all processes and their data and the compilation of the inventory tables. 

Life cycle assessment is defined by ISO 14040 as compilation and evalu ation of inputs, outputs and the potential environmental impacts of a product system throughout its life cycle. The ISO standards regulate the procedural aspects of LCA. They do not, however, provide all the information required for carrying out an LCA study. The main phases of LCA are goal and scope definition, inventory, impact assessment, and interpretation. The various applications of LCA are not regulated by the standard (Fig. 15.1). 

Moreover, calculations on the evaporation rate of bromine from the complex phase were carried out assuming a worst-case scenario, namely a complete spill age of the total bromine inventory (as poly bromide complex) of a fully charge (100% SOC) 15 kWh module which means -32.5 kg of available Br2, forming a 10 m2... 

The global design equations for packed beds—e.g.. Equations (10.1), (10.9), (10.39), and (10.40)—all have a similar limitation to that of the axial dispersion model treated in Chapter 9. They all assume steady-state operation. Adding an accumulation term, da/dt accounts for the change in the gas-phase inventory of component A but not for the surface inventory of A in the adsorbed form. The adsorbed inventory can be a large multiple of the gas-phase inventory. 

The parameter p (= 7(5 ) in gas-liquid sy.stems plays the same role as V/Aex in catalytic reactions. This parameter amounts to 10-40 for a gas and liquid in film contact, and increases to lO -lO" for gas bubbles dispersed in a liquid. If the Hatta number (see section 5.4.3) is low (below I) this indicates a slow reaction, and high values of p (e.g. bubble columns) should be chosen. For instantaneous reactions Ha > 100, enhancement factor E = 10-50) a low p should be selected with a high degree of gas-phase turbulence. The sulphonation of aromatics with gaseous SO3 is an instantaneous reaction and is controlled by gas-phase mass transfer. In commercial thin-film sulphonators, the liquid reactant flows down as a thin film (low p) in contact with a highly turbulent gas stream (high ka). A thin-film reactor was chosen instead of a liquid droplet system due to the desire to remove heat generated in the liquid phase as a result of the exothermic reaction. Similar considerations are valid for liquid-liquid systems. Sometimes, practical considerations prevail over the decisions dictated from a transport-reaction analysis. Corrosive liquids should always be in the dispersed phase to reduce contact with the reactor walls. Hazardous liquids are usually dispensed to reduce their hold-up, i.e. their inventory inside the reactor. 

Identify the inventories of flammable and combustible materials within the process plant and the physical conditions under which they are contained. Similarly, identify other materials or process conditions that can result in explosion events, including condensed-phase explosions, physical explosions, or uncontrolled chemical reactions. 

The inventory results should be presented in clear form, how much and what substances from the environment enter the system and how much get out. These results serve for subsequent life cycle impact assessment [48], The aim of the life cycle impact assessment is to measurably compare the environmental impacts of product systems and to compare their severity with new quantifiable variables identified as impact category. The impact categories are areas of specific environmental problems such as global warming, climate changes, acidification, eutrophication, ecotoxicity and others. Already in the phase of definition of the LCA study scope, it is necessary to describe what impact category will be applied and which of their environmental mechanisms will serve as a basis for impact assessment [46],... 

Carbenes form stable complexes with many metals in the periodic table of the elements, and gold is no exception. In fact, the chemistry of this class of organogold compounds for some time has been one of the fastest growing subdisciplines. While the corresponding chapters were still short in previous accounts,1 2 the inventory for this review is now particularly rich and diverse.230 As for other classes of carbene complexes, this upsurge is based on expectations for potential applications in various fields such as NLO materials, liquid crystalline phases, and catalysis. Where applicable, this is indicated for each of the entries in this chapter. 

For the supported catalyst it is expected that the ligand does not leach since it is chemically bonded to the carrier. In contrast, the rhodium metal bound to the ligand is subject to leaching due to the reversible nature of the complex formation. The amount will depend on the equilibrium between rhodium dissolved in the organic phase and that bound to the ligand. When an equilibrium concentration of 10 ppb Rh is attained, the yearly loss of Rh for a 100 kton production plant will be about 1 kg Rh per year. Compared to the reactor contents of rhodium (see Table 3.9, 70 kg Rh) this would result in a loss of 1.5% of the inventory per year, which would be acceptable. 

An exact calculation of inventory is difficult in the conceptual design phase, since the size of equipment is not usually known. The mass flows in the process are however known from the design capasity of the process. Therefore it is practical to base the estimation of inventory on mass flows and an estimated residence time. Consequently the inventory has been included to the ISI as a mass flow in the ISBL equipment including recycles with one hour nominal residence time for each process vessel (e.g. reactor, distillation column etc). For large storage tanks the size should be estimated. The total inventory is the sum of inventories of all process vessels. 

The size of settlers is determined by the rate of phase disengagement, which, here, is a function of the solvent concentration of LIX 64N and the aqueous phase feed rate. The capital cost of extraction equipment is a function of the number of tanks, the size of the tanks, and the solvent inventory [9] ... 

In one mixer-settler design, the mixed phases flow down a shallow trough placed over the settler, which gives them an opportunity to coalesce and separate before entering the settler. In this way, the capacity of the settler is markedly increased, with a concomitant reduction in the inventory of solvent required for a given duty. 

On the other hand, an increase in the fines (particles <40 p) content of the circulating catalyst usually points to an attrition source or a change in the fresh catalyst PSD. Attrition in the dilute phase will not be reflected in the inventory PSD. 

Radiochemical analysis of meta-studtite from an SNF test indicated that 237Np was associated with the U6+ peroxide (Table 3). Plutonium, Cm, and Am were found to be in lower concentration in the secondary U phases however, 5-6% of the available Pu and Am, based on reactor code estimates, was co-precipitated with the U phase. The radiochemical data for the collected alteration products from the SNF samples (Table 3) are presented as pg-analyte per g U for comparison to the reactor inventory code calculation for 30MW/d burn-up fuel at 20 y (extracted from Guenther et al. 1988). 

The inventory and impact assessment phases of LCA have different end results. The inventory component quantifies energy use, the masses of inputs, and the mass loadings of products, wastes, and releases on a systemwide basis. In contrast, the extrapolation of these mass-loading data generates a diverse spectrum of qualitative... 

Figure 2.7—Structure of polysiloxanes (silicones) and polyethylene glycols. An inventory of all the compositions of these phases that can be used for impregnation or bonding would be lengthy. The surface of the silica column can be treated with tetradimethylsiloxane in order to obtain the bound phase, which is polymerised and then cross-linked.

The initial assessment should be undertaken early in the planning phase and include definition of system boundaries in order to determine and document what systems are to be in the validation program and why. A sitewide inventory should assign each computer system a unique number, descriptive title, and location reference. The main software and hardware components of each system... 

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