Chemical Engineering May 2012 - 59

Develop
testing plans based on
water qualities
Onsite tests for 2 to 3
months to study the effects of
changing feedwater qualities and
operating conditions on
membrane performance
Optimize the pretreatment, UF and
RO process designs and
operating conditions
Engineering design and
construction
Plant implementation
FIGURE 9. Onsite membrane testing
is essential for recovery and reuse
of deeply treated WWTP effluent as
cooling-tower makeup water or boiler
makeup water
ments: (1) suspended solids of less
than 10 mg/L; and (2) total organic
carbon (TOC) or oil content less than
10 mg/L. Prior to its final purification
and reuse as boiler makeup water, the
recovered condensate may need to undergo
some pretreatment to remove
oil, iron and other contaminants and
to ensure that suspended solids are
less than 1 mg/L and TOC or oil is less
than 0.3 mg/L.
There are two alternative strategies
for this condensate recovery and pretreatment.
The first is applying heat
integration to recover the condensate
energy (for example, to use the hightempertaure
condensate to heat up the
desalted water and other low-temperature
process streams), and lower its
temperature to approximately 50°C
to enable a low-temperature recovery
and pretreatment by conventional
technologies. The second is applying
the latest high-temperature recovery
and pretreatment technology (≤85°C)
without lowering the condensate temperature.
In
a number of onsite testing programs
at Sinopec's refining and chemical
subsidiaries from September 2004
to October 2010, our project team
concluded that for a condensate recovery
capacity of approximately 300
ton/h, a high-temperature recovery
and preatment technology that combines
the active ceramic-molecular
membrane ultrafiltration with the
functional-group-activated carbon-fiber
adsorption appears to be efficient
and economical. At least nine Sinopec
subsidiaries and 24 other petroleum
refining and chemical plants in China
have implemented this technology as
of July 2011 [10].
Prior to last year, there had been no
successful experience of applying this
technology - at least within China -
to a large-scale condensate recovery
system with a capacity of over 1,100
ton/h. Additionally, in this particular
ethylene plant, there is a great need
for low-temperature heat sources to
heat up some process streams. Thus,
the final implementation of the condensate
recovery system in this ethylene
plant follows the following process
scheme: process optimization and
heat integration; followed by lowering
of condensate temperature and heat
recovery; then low-temperature recovery
and pre-treatment. The final purification
of the recovered condensate
uses conventional activated-carbon
filtration, followed by an ion-exchange
operation.
CORPORATE SUPPORT
In addition to improved water management
and application of new technologies,
water-saving efforts in large
petroleum refining and chemical companies
depend on an environment of
corporate support to be successful.
The support should take the following
forms: 1) strong support by senior
executives and production managers;
2) company-wide training of project
teams; and 3) serious promotion of
corporate-wide enthusiasm for water
savings.
Developing and implementing substantial
water savings can allow large
petroleum refining and chemical companies
to expand production capacities
without having to secure additional
freshwater sources or enlarge their
wastewater treatment facilities. For
example, despite a significant increase
in annual sales revenue from 2000 to
2011, a proactive, company-wide watersaving
initiative at the Sinopec subsidiary
in Yanshan actually dropped its
freshwater consumption from 68 to
20.74 million ton/yr, while increasing
wastewater regeneration, recycling
and reuse to 7.4 million ton/yr.
■
Edited by Scott Jenkins
References
1. Tullo, A. H. Global Top 50, Chem. & Eng. News,
89(30), pp. 12-15, 2011.
2. Integrated Pollution Prevention and Control
(IPPC) Directive, Guidance for Best Available
Technology for Reduction of Discharges to
Water, European Union, p. 399, July 2003.
3. Mann, J. G. and Y. A. Liu. " Industrial Water
Reuse and Wastewater Minimization " , McGrawHill,
New York, 1999.
4. Liu, Y. A., B. Lucas and J. W. Mann. Up-to-date
Tools for Water System Optimization, Chem.
Eng., January 2004, pp. 30-40.
5. Metcalf & Eddy, Inc., " Wastewater Engineering:
Treatment and Reuse " , 4th ed., revised by G.
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6. Hu, H., Refinery Heat Integration and Hot Material
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Author
Y. A. Liu is the Frank C. Vilbrandt
Endowed Professor
of Chemical Engineering at
Virginia Polytechnic Institute
and State University (Virginia
Tech; Blacksburg, VA 24061;
Phone: 540-231-7800; Email:
design@vt.edu). Liu has taught
hands-on training courses on
energy and water savings,
computer-aided design and
advanced process control to over 6,000 practicing
engineers in the U.S., China and Taiwan. He has
served as senior advisor to the office of the president
of Sinopec during winter and summer university
breaks since 2001. With his doctoral students,
he has published five pioneering textbooks
in chemical engineering, on artificial intelligence
(Academic Press, 1991), neural networks (Academic
Press, 1995), water reuse and wastewater
minimization (McGraw-Hill, 1999), step-growth
polymerization process modeling and product
design (Wiley, 2008), and refinery engineering
(Wiley-VCH, 2012). He is a recipient of the George
Westinghouse Award and Fred Merryfield Design
Award from the American Society for Engineering
Education, the Outstanding Faculty Award from
the Virginia's governor, and the National Friendship
Award from the China's premier. His research
group at Virginia Tech has been designated as the
Sinopec and AspenTech Center of Excellence in
Process System Engineering since 2002.
Acknowledements
The author thanks Mr. Wang Jiming, Past President,
Mr. Wang Tianpu, president, Mr. Cao Xianghong,
past senior vice president and chief technology
officer of Sinopec, and Mr. Wilfred Wang,
past chairman of Formosa Petrochemical Corp.,
for their strong support of water-saving projects.
The author also thanks Aspen Technology, Inc.,
Sinopec, Milliken Chemical, Alliant Techsystems,
Novozymes Biological, and Mid-Atlantic Technology,
Research and Innovation Center, for their
support of the Center of Excellence in Process
System Engineering at Virginia Tech.
CHEMICAL ENGINEERING WWW.CHE.COM MAY 2012 41
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