Heat Up Your Heat Transfer
Know-How
Heat Transfer eHANDBOOK
TABLE OF CONTENTSFree Up More Tubular Exchanger Area 5
Consider options besides changing bundle pitch when debottlenecking
Take a Closer Look at Direct Steam Injection 9
Technology responds rapidly to changing process conditions
Modular Boiler Systems Offer Flexibility 11
Compact size and start-up speed help to meet changing requirements
Additional Resources 14
AD INDEXPick Heaters • pickheaters.com 2
Miura • miuraboiler.com 4
Xylem • xylem.com/standardxchange 8
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 3
www.ChemicalProcessing.com
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Design margins incorporated in
most plants and equipment often
offer a cost-effective way to
increase asset utilization. Over time, a
site can use design margins to raise plant
capacity or improve product quality. How-
ever, constraints posed by just one or two
items frequently hinder overall improve-
ments — and make debottlenecking that
equipment important.
One recent example was a plant that
wanted to raise product yields at its cur-
rent capacity. Key to that was heating the
feed to a higher temperature. The feed was
heated by a combination of heat integration
followed by a fired heater. The plant already
was using all the spare duty capacity of
the fired heater. So, the most straightfor-
ward approach to get the additional duty
required was to modify the heat integra-
tion system.
The heat integration exchangers were
installed in a multi-level structure. Code
limitations precluded adding significant
weight to that structure. In addition, the
site only had limited open area suitable for
new equipment.
Modifications targeted two elements.
First, pinch analysis showed that one
exchanger in the existing heat integration
was nearly completely ineffective. Remov-
ing that exchanger would open up both
space and weight capability for installing a
much-more-effective heat integration unit.
Second, minor changes — even as little
as 5–6% more duty in specific services —
would provide significant benefits. So, here,
Free Up More Tubular Exchanger AreaConsider options besides changing bundle pitch when debottleneckingBy Andrew Sloley, Contributing Editor
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 5
www.ChemicalProcessing.com
we’ll look at how the plant got this extra
duty from a heat exchanger.
Figure 1 illustrates the tube-sheet layout
of one exchanger in the plant. It is a par-
tial-condensing exchanger with hot fluid
(vapor) on the shell side and cold fluid
(liquid) on the tube side. The exchanger
is a TEMA E-type shell with eight passes
on the tube-side, and downward shell-
side condensing flow. The pinch analysis
showed that nearly all exchangers in the
plant, including this one, were surface area
limited. Adding surface area would increase
exchanger duty most effectively.
Perhaps the most obvious change would
have been to switch the bundle pitch from
rotated square to triangular. This would
have allowed more tubes, increasing sur-
face area. However, because the exchanger
was in a fouling service, the benefits of
easier cleaning of the rotated-square pitch
outweighed the additional surface area pos-
sible with a triangular pitch.
Immediately downstream of the exchang-
er’s inlet nozzle is an open area with no
tubes and an impingement plate. If tubes
are too close to the inlet nozzle, they block
a large fraction of the flow area, creating
pressure drop and high inlet velocities. The
open area between the inlet nozzle and
tube bundle allows the vapor to flow along
part of the shell length before entering the
tubes. Effectively, this increases the inlet
area for vapor flow into the bundle.
The impingement plate prevents high veloc-
ity vapor from jet-impinging onto the tubes.
The vapor contains some liquid droplets, so
high velocity impingement could cause ero-
sion or other mechanical damage.
Providing open area under the inlet nozzle
is a conventional approach in exchanger
design. Open area also is used next to the
outlet nozzle if high velocities are expected
there as well. In this case, the tube removal
reduces the area possible in that shell diam-
eter by approximately 6%. So, decreasing
the inlet velocity another way would allow
TUBE LAYOUTFigure 1. Open area under the inlet nozzle for velocity reduction robs area available for the exchanger bundle.
Flow In
Flow Out
Area open for flow entry
www.ChemicalProcessing.com
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 6
replacing the exchanger bundle with one
having 6% more area.
Two other methods of inlet velocity reduc-
tion are possible: a dome at the inlet; or a
vapor belt that circles, or partially circles,
the shell to allow vapor into the bundle
at multiple locations. Both increase the
inlet area open for flow and decrease
inlet velocity.
Here, the plant opted for a vapor belt
because it required fewer external piping
modifications. Both the vapor belt and the
extra tubes added weight to the exchanger.
Keeping the weight within the allowable
limit required making the tubes and tube
sheet of thinner material.
While the modifications may seem extreme
for just 6% more duty, the extra feed heat
was critical and allowed for more product
recovery.
ANDREW SLOLEY is a contributing editor for Chemical
Processing. Email him at [email protected]
Other methods of inlet velocity reduction are possible.
www.chemicalprocessing.com/podcast/process-safety-with-trish-and-traci
Trish Kerin, director of IChemE Safety Centre, and Chemical Processing’s Traci Purdum discuss
process-safety issues offering insight into mitigation options and next steps.
From questioning if inherently safer design is really safer to lessons learned from significant
incidents, these podcasts have one goal:
To ensure workers return home safely after every shift.
PROCESS SAFETY
With Trish & Traci
www.ChemicalProcessing.com
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 7
For over 100 years, Standard Xchange heat exchangers have kept mission-critical systems up and running. Today we still set the standard – engineering and building the most reliable, innovative heat transfer technology in the USA. So whether you’re looking for a part or building a plant, you know you’ll get the optimal heat transfer solution.
Find out what we can do for you at xylem.com/standardxchange
Inline heating of liquids or slurries is a requirement in many chemical and pharmaceuti-
cal operations as numerous industrial applications need an unlimited and instantaneous
supply of hot water.
While choices for heating water, liquids and slurries abound, direct steam injection (DSI) heaters
(Figure 1) should be at the top of the list of options for these challenging applications.
WHY CHOOSE DSI? DSI has certain characteristics that are ben-
eficial or even necessary depending on
the process:
• It offers precise temperature control within
±1 °C.
• It is easy to install and can be used wherever
medium- to high-pressure steam is available.
• Precisely machined variable orifice injector
with spring-loaded piston eliminates damag-
ing vibration and steam hammer.
• Compared to alternatives such as tank steam
sparging or indirect heat exchangers, DSI
Take a Closer Look at Direct Steam InjectionTechnology responds rapidly to changing process conditions
By Paul Pickering, Pick Heaters Inc.
DIRECT STEAM INJECTION HEATERSFigure 1. These units are an ideal choice when a well-controlled, instantaneous supply of water is needed.
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 9
www.ChemicalProcessing.com
heaters can cut fuel costs by as much
as 28% because the liquid absorbs 100%
of the available energy (BTUs) from the
steam instantly.
• It features a low liquid-side pressure drop
— less than 2 psi.
• It is environmentally safe and nonflamma-
ble, unlike heat transfer fluids that require
special handling and constant monitoring.
EXAMPLES OF DSI IN INDUSTRIAL PROCESSESDSI is better than indirect exchangers for
heating water in industrial applications
because it provides a rapid response to
changing process conditions and enables
precise temperature control within a
single degree Celsius. As such, DSI heat-
ing is suitable for a variety of industrial
processes as illustrated in the follow-
ing examples:
• Many processes in the chemical industry
require water temperature to be con-
trolled precisely before adding it to a
batch process. A DSI system provides
instant temperature control, reducing the
cycle time and increasing productivity.
• DSI also is ideal for heating large-capacity,
closed-loop jacketed vessels, tanks and
blenders; mixing two condensate steams;
or even dispersing gas into a liquid.
• Applications such as plant sanitization,
clean-in-place (CIP) and washdown hose
stations require hot process water. Instan-
taneous and accurately controlled hot
water must be available to meet stringent
plant demands.
• In pharmaceutical processing, DSI tech-
nology is used in such applications as the
continuous-flow heat treatment of bio-
waste. The precise temperature control
enables wastewater with living cells to
be killed or inactivated and then cooled
before disposal. For example, one waste
steam inactivation system required the
waste from multiple reactors to be heated
to 140 °C, held for a period of time and
then cooled to 60 °C. Read more here.
PAUL PICKERING is a writer for Pick Heaters Inc. Pick
Heaters produces DSI heaters in 10 standard sizes for
liquid flow rates up to 5,000 gpm, and steam flow
rates from 150 lb/hr to 50,000 lb/hr. For more infor-
mation, visit www.pickheaters.com/Products.htm.
DSI provides a rapid response to changing process conditions and enables precise temperature control
within a single degree Celsius.
www.ChemicalProcessing.com
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 10
Chemical processors have been chal-
lenged to rethink certain operations,
and having options has become a
valuable asset.
Whether you are facing a crisis or need to
be able to adjust your steam requirements
quickly, you’ll want to consider a modular
boiler system that maximizes flexibility and
provides a range of advantages for stay-
ing competitive and meeting production
demands.
Modular steam systems comprise multiple
connected steam boilers configured to meet
demand at different stages to provide just
the right amount of steam only when steam
is required.
Typically, modular boilers feature a fast
start-up that can achieve full steam from
a cold start in less than five minutes and
shut down just as promptly (Figure 1). This
gives processors critical advantages, includ-
ing features that support environmentally
friendly initiatives, maximize in-service
efficiency, conserve resources, reduce emis-
sions and control fuel costs.
In 2020, we witnessed a radical shift in the
entire U.S. economy, making it essential for
companies that needed to increase steam
production quickly, as well as those who
needed to closely monitor their output, to
be able to do so rapidly while adjusting to a
climate of continued uncertainty.
Now, a little more than a year later, as we con-
tinue to make our way back, lessons learned
should never be forgotten, and being able to
react and respond quickly should be the basis
for investing in a steam boiler system.
Modular Boiler Systems Offer FlexibilityCompact size and start-up speed help to meet changing requirements Andrew Eklind, Miura
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 11
www.ChemicalProcessing.com
STEAM THAT MEETS YOUR NEEDSAchieving full steam in minutes and plac-
ing boilers in standby mode quickly based
on the current steam demands, rather than
continuing to have them in an idle state
to stay warm, no longer can be thought
of as an interesting concept. It is an abso-
lute necessity.
This also applies to having the capability
to add a boiler fast, whether it is required
to expand steam output quickly, replace a
failing unit that seems to require daily main-
tenance or get you back up on your feet in
the aftermath of a natural disaster.
In the past, this often meant relying on rental
boilers to increase steam capacity tempo-
rarily, but the price is high, and it requires
installing and uninstalling the boiler. These
additional steps can be expensive, especially
if you’ve ordered a new boiler and are wait-
ing weeks or months to receive it.
More cost-effective and efficient solu-
tions can have a new boiler delivered to
you in approximately 48 hours, ready for
a quick, one-time installation, an option
that saves money and provides tremen-
dous flexibility.
BIG ADVANTAGES TO COMPACT DESIGNBigger is not always better, especially when
you are trying to add additional boiler units
to an existing boiler room. Modular boil-
ers feature upright pressure vessels, which
take up less floor space and can usually
be added even if your current boiler room
space is limited.
This is advantageous where real estate and
construction prices continue to go up or
where more space simply is unavailable.
Choosing a compact, low-water-content
modular boiler makes installation, operation
and maintenance much easier while provid-
ing greater output in less space. Modular
systems are replacing traditional boiler sys-
tems to increase steam capacity without
having to construct a new boiler room.
Taking these and other features and
advantages into account, it also is
STEAM FLOWFigure 1. The “floating header” design produces steam in less than 5 minutes, allowing users to turn boilers on or off as needed.
www.ChemicalProcessing.com
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 12
important to consider a boiler that
provides “only the steam you need,
when you need it.”
For example, some modular steam
boilers in multiple installations (MI)
adjust automatically to fit your steam
demands, so when you only require
30% of the full system output, the
system is using only 30% of the boiler
system capacity. The other 70% of
the system remains in standby mode,
using only relatively small amounts
of electricity to keep the communica-
tion system online.
Known as load-following technology, this pro-
vides a tremendous cost and resource-saving
advantage, especially as traditional systems
continue to use 100% of the system just throt-
tled down to produce less steam.
Investing in modular boiler systems that pro-
vide greater flexibility and green features
means being able to optimize your system for
your unique steam load, rather than oversiz-
ing your boiler system, as that strategically
may prove to be a bad investment. Mod-
ular boiler systems often are custom-sized
to meet your current requirements and
can grow cost-effectively as the situa-
tion demands.
STEAM-AS-A-SERVICEAnother option for large steam generation
facilities introduced around the start of
2020 is Steam-as-a-Service (SaaS), an inno-
vation that requires no upfront costs and
delivers state-of-the-art, fully-controlled
steam for a monthly fee.
This service has been developed by Miura
and its alliance partners, Hartford Steam
Boiler and Armstrong Services, to provide
an all-in-one solution.
BENEFIT FROM FLEXIBLE STEAM Flexible options are essential to better
preparation. As such, steam users need to
take a closer look at proven technologies
that address a range of possible concerns
and allow them to take advantage of new
services and innovations that make it easier
to operate within an environment of change
to meet current and future challenges.
ANDREW EKLIND is marketing manager for Miura. Con-
tact him at [email protected].
MULTI-UNIT SETUPFigure 2. Load-following technology in multiple installations, automatically adjusts steam output to provide the right amount needed.
www.ChemicalProcessing.com
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 13
Heat Transfer eHANDBOOK: Heat Up Your Heat Transfer Know-How 14
ADDITIONAL RESOURCESEHANDBOOKSCheck out our vast library of past eHandbooks that offer a wealth of information on a single topic,
aimed at providing best practices, key trends, developments and successful applications to help make
your facilities as efficient, safe, environmentally friendly and economically competitive as possible.
UPCOMING AND ON DEMAND WEBINARSTap into expert knowledge. Chemical Processing editors and industry experts delve into
hot topics challenging the chemical processing industry today while providing insights and
practical guidance. Each of these free webinars feature a live Q&A session and lasts 60 minutes.
WHITE PAPERSCheck out our library of white papers covering myriad topics and offering valuable insight
into products and solutions important to chemical processing professionals. From automation
to fluid handling, separations technologies and utilities, this white paper library has it all.
PODCAST: PROCESS SAFETY WITH TRISH & TRACITrish Kerin, director of IChemE Safety Centre, and Chemical Processing’s Traci Purdum discuss
current process safety issues offering insight into mitigation options and next steps.
ASK THE EXPERTSHave a question on a technical issue that needs to be addressed? Visit our Ask the Experts
forum. Covering topics from combustion to steam systems, our roster of leading subject
matter experts, as well as other forum members, can help you tackle plant issues.
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the winning caption and all submissions
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