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Heat Integration (heat + integration)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Efficiencies of NaOH production methods in a Kraft pulp mill

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2009
Tobias Richards
Abstract There are several processes in a Kraft pulp mill where there is a need for sodium hydroxide, e.g. in the digester and the bleaching plant. The objective of this study is to perform a preliminary evaluation, intended to select the best alternative for producing sodium hydroxide on a Kraft pulp mill site. The first step of the evaluation consists of screening available processes for producing sodium hydroxide needed in the mill. The first step of the evaluation shows that the two best options for increasing the production of sodium hydroxide for internal use in a mill are the conventional lime cycle process or direct causticization with titanates. The second step of the evaluation compares the lime cycle and the titanate process using first and second law analyses to determine the energy requirement and the exergy efficiencies of both processes. Such analyses show a higher energy requirement and a lower exergy efficiency in the titanate process than in the lime cycle process without any heat integration. However, the titanate process shows better performance in terms of energy requirement and exergy efficiency than the lime cycle, if heat is integrated into both processes. The titanate process requires, in the best case, only 80% of the energy required for a fully heat-integrated lime cycle process. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Internal heat integration , the key to an energy-conserving distillation column,

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2-3 2003
Z Olujic
Abstract This paper illustrates the thermal energy conservation potential of the so-called heat integrated distillation column (HIDiC), which combines advantages of direct vapour recompression and diabatic operation at half of the normal column height. In a typical close boiling mixture separation, compared with a column utilising the usual vapour recompression scheme, HIDiC halved the consumption of exergy at approximately the same capital cost, indicating a strikingly short pay-off time. The complexities of integrating the heat transfer equipment in the stripping section with proven gas/liquid contacting devices, which may work adversely to practical implementation of HIDiC concept, are also addressed. © 2003 Society of Chemical Industry [source]

Assessment of the Automobile Assembly Paint Process for Energy, Environmental, and Economic Improvement

JOURNAL OF INDUSTRIAL ECOLOGY, Issue 1-2 2004
Geoffrey J. Roelant
A coat of paint adds considerable value to an automobile. In addition to consuming up to 60% of the energy needed by automobile assembly plants, however, the painting process also creates both economic and environmental impacts. This study investigated the degree of cost and environmental impact improvement that can be expected when modifications are considered for existing paint processes through heat integration. In order to accomplish this goal, a mathematical model was created to describe the energy use, costs, and environmental impacts from energy consumption in an automobile assembly painting facility. The model agrees with measured energy consumption data for process heating and electricity demand to within about 15% for one Michigan truck facility from which model input parameters were obtained. Thermal pinch analysis determined an energy conservation target of 58% of paint process energy demand. A heat exchanger network optimization study was conducted in order to determine how closely the network design could achieve this target. The resulting heat exchanger network design was profitable based on a discounted cash flow analysis and may achieve reductions in total corporate energy consumption of up to 16% if implemented corporatewide at a major automobile manufacturer. [source]

Energy optimization for the design of corn-based ethanol plants

AICHE JOURNAL, Issue 6 2008
Ramkumar Karuppiah
Abstract In this work, we address the problem of optimizing corn-based bioethanol plants through the use of heat integration and mathematical programming techniques. The goal is to reduce the operating costs of the plant. Capital cost, energy usage, and yields,all contribute to production cost. Yield and energy usage also influence the viability of corn-based ethanol as a sustainable fuel. We first propose a limited superstructure of alternative designs including the various process units and utility streams involved in ethanol production. Our objective is to determine the connections in the network and the flow in each stream in the network such that we minimize the energy requirement of the overall plant. This is accomplished through the formulation of a mixed-integer nonlinear programming problem involving short-cut models for mass and energy balances for all the units in the system, where the model is solved through two nonlinear programming subproblems. We then perform a heat integration study on the resulting flowsheet; the modified flowsheet includes multieffect distillation columns that further reduces energy consumption. The results indicate that it is possible to reduce the current steam consumption required in the transformation of corn into fuel grade ethanol by more than 40% compared to initial basic design. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]