The Economics of Antifoulant Application

The performance of heat integration systems is normally quantified in terms of the amount of heat that is recovered. In an effort to mitigate the usual decrease in heat recovery with time due to fouling of the heat transfer surface, various chemical additives can be utilized. Using the "Total Fouling Related Expense (TFRE)" approach, the economics of antifoulant application are evaluated based on the optimum exchanger cleaning interval. Sensitivities to antifoulant effectiveness are calculated and procedures which can be used to evaluate the economic optimum use of antifoulants are described

Optimization of Heat Exchanger Cleaning

The performance of heat integration systems is quantified in terms of the amount of heat that is recovered. This decreases with time due to increased fouling of the heat exchange surface. Using the "Total Fouling Related Expenses (TFRE)" approach, economic incentives for heat exchanger cleaning are evaluated using linear, exponential, and exponential finite decrease models of the heat recovery decay. A mathematical comparison of mechanical and chemical cleaning of heat exchangers has identified the most significant parameters which affect the choice between the two methods

Application of Pinch Technology in Refinery Retrofits

This paper reviews the application of pinch technology in the identification of the most attractive retrofit prospects in typical refineries. In the first part of the paper, methodology is described to identify attractive inter-unit heat integration opportunities as well as attractive process-utility system integration (co-generation). An example of an atmospheric pipestill-alkylation unit integration evaluation is given using both composite stream and Grand composite stream methods. In the second part of the paper, the application of pinch technology in a typical intra-unit heat integration problem is given. It is explained how inefficiencies in an APS crude preheat train are identified, and a typical small retrofit project is described

Adaptation Models for Network-Aware Distributed Computations

service they receive from the network. This allows the application to execute well over a diverse set of networks and under a wide range of network conditions. However, network diversity and dynamic network conditions make the development of network-aware applications a difficult task, since the developer has to be an expert in both the application domain and networking. In this paper we look at a number of network-aware applications and identify three adaptation strategies that have proven to be effective. These strategies can be viewed as adapation models that capture the essential structure of the adaptation process. Similar to the use of programming models in parallel and distributed computing, adaptation models can be used to guide the development of other network-area applications and they can also form the basis for programming support, e.g. middleware, that supports the development of network-aware applications. We describe these three adaptation models, compare their features and applicability, and briefly discuss how these models impact the design of middleware that supports network-aware applications