Page 238 - Sustainability in the Process Industry Integration and Optimization

S o f t wa r e T o o l s 215

including Combined Heat and Power (CHP), fuel cells, and
photovoltaic technology; new homes built with nearly zero carbon
emissions; (6) natural gas; (7) coal-fired generation combined with
carbon capture and storage; and (8) mixed fuels (e.g., coal mixed
with biomass, natural gas mixed with hydrogen). Longer-term
prospects include nuclear power stations, fuel cells, hydrogen
obtained from nonelectricity sources (e.g., biomass, low-carbon
biofuels), and nuclear fusion.

9.8.3 Balancing and Flowsheeting Simulation for
Energy-Saving Analysis

Tools for balancing, reconciliation, and flowsheeting simulation are
frequently used for energy-saving analysis and have become an
essential item in the process engineer’s toolbox. These tools help
designers develop complete mass and energy models based on actual
measurements and/or design values and mathematical models. As a
result, these simulation tools play an important role in the technical
and economic decision making related to the planning and design
stages of processes under development and to the operation of
existing equipment. Several computer-based systems have been
developed over the years in order to assist process engineers with
energy and mass balance calculations. However, ongoing development
costs have resulted in a limited number remaining on the market,
and these have been secured only by a substantial volume of sales.
An early overview of the field was presented by Klemeš (1977).
The technology used for balancing and for data validation and
reconciliation consists of a set of procedures incorporated into a
software tool. Process data reconciliation has become the main
method for monitoring and optimizing industrial processes as well as
for performing component diagnosis, condition-based maintenance,
and online calibration of instrumentation. According to Heyen and
Kalitventzeff (2007), reconciliation has three main goals: (1) detect
and correct deviations and errors of measurement data so that all
balance constraints are satisfied; (2) exploit the structure of and
knowledge about the process system by using measured data to
estimate unmeasured data whenever possible, in particular as
regards key performance indicators (KPIs); and (3) determine the
postprocessing accuracy of measured and unmeasured data,
including KPIs.
A comprehensive system called DEBIL—which included
balancing, flowsheeting simulation, and optimization—was created
several decades ago (see Klemeš, Luťcha, and Vašek, 1979) and has
since been further developed by Belsim into the balancing and
reconciliation tool VALI (VALI III User Guide, 2003). This tool has been
applied to various energy-efficiency tasks, as reported with respect
to nuclear power plants (Langenstein, Jansky, and Laipple, 2004) and
regenerative heat exchangers (Minet et al., 2001).