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TITLE: DEVELOPMENT OF A SMART PUMPING SYSTEM
1
TITLE: DEVELOPMENT OF A SMART PUMPING SYSTEM
Authors:
A.E. Stavale, Sr. Project Manager, Author#1
Phone: 315-568-4021
E-Mail:
astavale@fluids.ittind.com
J.A. Lorenc, Sr. Research Engineer, Author #2
Phone: 315-568-7178
E-Mail:
jlorenc@fluids.ittind.com
E.P. Sabini, Director Technology, Author #3
Phone: 315-568-7523
E-Mail:
gsabini@fluids.ittind.com
Fax (for all): 315-568-7709
Company (for all): ITT Industries, Fluid Technology Corp.-Industrial Pump Group,
Seneca Falls, New York 13148
SYNOPSIS
A smart pumping system was successfully developed in response to a challenge by a major
chemical user to reduce the total cost of pump ownership. The system is fault tolerant and will
significantly reduce all major components of life cycle cost. 2
DEVELOPMENT OF A SMART PUMPING SYSTEM
ABSTRACT
In todays global economy, process plants are under constant pressure to reduce costs. Users can no
longer afford their attempts to make pumps bulletproof by upgrading component specifications. The
development of a smart pumping system was fostered by a challenge from a major chemical user to
reduce the total cost of pump ownership. A smart pumping system was successfully developed that can
react and adjust itself to system changes without manual intervention.
The system is fault tolerant by virtue of the control software, which will not permit the pump to operate
outside user specified ranges, or under conditions that typically cause pumps to fail. A variable speed
controller can match pump output to exact system head requirements, without the need for energy
consuming control valves. The smart pumping system can significantly reduce all major components of
life cycle cost.
Field-testing proceeded without incident after initial installation problems were resolved.
INTRODUCTION
To survive in the global marketplace, process plants are under constant pressure to move liquids both
reliably and inexpensively. Today many plants have cut back on operating and maintenance personnel
and are often left with inexperienced people. This presents a dilemma; users can no longer afford their
attempts at making pumps bulletproof (Swalley, 1999) and the exodus of experienced personnel only
serves to exacerbate their predicament.
As a result, a major chemical user issued a challenge to drastically reduce the total cost of pump
ownership in their plants. They presented a specification for the desired performance of this futuristic
pump, covering the following key items:
50,000 hour Mean Time Between Failure
Ability to survive 10,000 start-stops
Able to run dry
Operating temperature range 100
�
F to 700
�
F
Capacities to 7500 gpm, heads to 1075 ft
Pump to be unaffected by 2 years non-operation
Easy to decontaminate
Operation on 50 or 60 Hz
Standardized connections and locations
Technical and service support as needed
First cost 25% less than equipment replaced (pump, seal, motor, baseplate, coupling and guard)
Rebuild cost less than 50% of new assembly
The above items can be segregated into those that can be handled by proper pump selection, materials
and construction and those that are more challenging to todays state-of-the-art pump design. This paper
will focus on the design challenges (shown in Italics) and presents a novel approach to reducing the total
cost of pump ownership. 3
ALTERNATIVES CONSIDERED
Heavy Duty Pump
Nearly all of the design challenges identified above either directly or indirectly have an influence on
increasing the Mean Time Between Failure (MTBF) of a pump. One approach to increasing MTBF might
be to design a heavier duty pump, one with a larger shaft and bearings, more liberal internal clearances
and thicker casing. However, clearly this approach is at odds with the requirement that the first cost be
25% less than the equipment being replaced. A heavy-duty close coupled Vertical Inline (VIL) pump could
be designed which will eliminate the cost of the pump coupling, coupling guard and baseplate. It would
also eliminate any maintenance costs relating to coupling mis-alignment and excessive nozzle loads due
to poor baseplate/foundation stiffness. Installation costs could also be reduced due to the elimination of
baseplate setting and grouting work. Although this approach appears to make for a more robust pump
design and contributes to some reduction in initial cost, maintenance cost and installation cost, it does not
address pump failures caused by operator error or system upsets. A pump with an extra heavy shaft and
bearings will fail just as quickly as a standard pump when operating in a dry run condition or against a
closed suction or discharge valve.
The two primary causes of failures in centrifugal pumps relate to bearings and seals. There are many
reasons for failures of these components. Some are application related such as operation outside
specified flow regimes and inadequate NPSHA. This can result in increased vibration, bearing loads,
shaft deflection, recirculation damage and a poor seal chamber environment that is counterproductive to
long seal life. Other reasons relate to improper installation techniques that can cause alignment problems
due to pipe strain and poor baseplate and foundation stiffness. Clearly, many technical articles, books
and manufacturers guidelines exist today, which promote proper pump application and installation. Yet
the norm in MTBF for chemical process pumps is only about 24 months. This is well below the MTBF for
the refining industry, which approaches 5 years (Erickson, et. al., 2000). Logic would indicate that MTBF
could be improved further by designing the pump to be more fault tolerant. Fault tolerance protects the
pump from damage if it is forced outside the desired operating envelope. This protection can be achieved
through a combination of mechanical design, materials of construction and protective devices.
Another opportunity to reduce the total cost of ownership is to minimize energy consumption. Advances in
hydraulic design and computerized tools such as Computational Fluid Dynamics (CFD) have significantly
reduced the opportunities for further improvement in pump efficiency. However, many articles have been
written concerning the significant opportunity to reduce energy consumption with variable speed
operation. It is not unusual to achieve a 50% reduction in energy consumption and an increase in pump
reliability when using a variable frequency drive (Hovstadius, et. al., 2000). Maintenance and operating
costs are two of the largest opportunities for reducing the total cost of pump ownership and cannot be
ignored. For this reason the heavy-duty pump design concept was removed from further consideration.
Computer Controlled /Artificial Intelligence Pump
A novel concept considered was to design a system rather than a pump. This system would consist of a
standard centrifugal pump, a variable speed drive, instrumentation, a microprocessor and special
software. There are several objectives that this system would be expected to accomplish. If a variable
speed drive is employed, operating costs could be reduced significantly by eliminating the pressure drop
across a control valve. Fault tolerance could also be built into the pumping system by developing special
software that would interact with instrumentation signals that sense process conditions. The software
would require the ability to recognize and prevent the pump from operating under damaging conditions.
Finally, if a method could be developed to use the pump casing as a flow-measuring device; in many
applications the need for a separate flow meter would be eliminated.
The total cost of pump ownership could clearly be reduced by decreased energy and maintenance costs.
Additionally, the opportunity to eliminate equipment such as a control valve, external flow meter, separate
starter and recirculation line piping could also decrease initial and installation costs. There would be 4
additional costs associated with the purchase and installation of a variable frequency drive and
instrumentation; however it was expected that the aforementioned savings could offset these costs in
many cases. It was concluded that this concept approach had merit since it worked at significantly
reducing all of the major components of the total cost of pump ownership.
VISION OF A SMART PUMPING SYSTEM
What It Should Do
A smart pumping system must be capable of knowing when to adjust itself to system changes without
manual intervention and must match pump output exactly to system head requirements. If upstream
conditions change due to a system transient the pump should either increase or decrease its speed in
order to maintain a constant o