Page 29 - Sustainability in the Process Industry Integration and Optimization

6 Cha p te r O n e

establishes policies and objectives and also develops ways of
applying the policies to achieve the objectives.
• Responsible use of energy: in (1) energy procurement,
(2) metering and billing, (3) performance measurement,
(4) policy development, (5) assigning energy management
responsibility, (6) energy surveying and auditing, (7) training
and education, and (8) capital project management.

The steps listed here have been found by the U.K. Energy Efficiency
Best Practice Programme (EEBPp, 2002) to be central to any resource
and waste management program. Energy screening and scoping
audits fall into three main categories whose use (either individually
or in combination) is based on the required depth of the study, the
process to be analyzed, and the plant size: (1) the walk-through audit,
which provides a quick snapshot of certain opportunities; (2) the
detailed audit, which conducts an in-depth analysis of specific
components; and (3) the Process Integration audit, which analyzes the
plant as a whole and takes a systematic look at all processing steps and
their interconnections.
Audits may be performed by plant personnel, by external experts,
or by teams with members from both groups. Although there are
many possible options and levels of detail, typical activities include
the following (NRCan, 2007):

1. Determination of the production “base case” and the
reference period.
2. Collection of energy total consumption and cost (information
usually available from fuel records, electricity invoices, etc.).
3. Development of a process flow chart that shows materials,
energy inputs, and energy outputs for the main processing
steps.
4. For the largest consumers, collection of energy data from
the plant metering devices, control systems, and process
flow diagrams (if current operating conditions are close to
design data).

In terms of the time required for (and other costs of) identifying
opportunities to save energy, one efficient approach is the top-level
analysis (Varbanov et al., 2004). This procedure accounts for investment
limits or allowances and identifies economically justifiable energy-
saving opportunities, listing them in the order of their expected
economic return. Measurements can be performed using portable
instruments (flow rate, temperature, humidity, etc.) to determine the
overall plant production of steam, refrigeration, compressed air, and
hot water. Interviews with key personnel and operators can also
provide valuable information about plant operations.