Urea 2000plus TM Pool Condenser Prem Baboo National Fertilizers Ltd. India Introduction Back in the late sixties, the development of the Stamicarbon CO 2 stripping process revolutionized urea process technology. The introduction of Stamicarbon's Urea 2000plus TM in 1996, was yet another milestone. By combining equipment, our engineers have been able to reduce the number of high pressure vessels in the process, thereby also simplifying the overall design, piping and construction. The result: a considerable lowering of investments and operating costs.The Pool Condenser concept was the first step in the development of this technology. A second step was the introduction of the Urea 2000plus TM Pool Reactor concept, which has been built at DSM in Geleen, The Netherlands, with a capacity of 1150 mt/d. Stamicarbon can offer this process in its pool condenser alternative in single train capacities up to 3,250 mt/d. This capacity range again signifies an improvement over today's plants, which have typically been designed for around 2000 mt/d. The Pool condenser In the effort to develop the pool condenser, use was made of extensive experience gained in urea plants of our licensees in which similar condensers are used for different purposes and from the extensive process database available at Stamicarbon. Basically, the pool condenser is a horizontal vessel with a submerged U-tube bundle. It is fabricated from carbon steel with internals and lining in stainless steel.
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Urea 2000plusTM Pool Condenser
Prem Baboo
National Fertilizers Ltd. India
Introduction
Back in the late sixties, the development of the Stamicarbon CO2 stripping process
revolutionized urea process technology. The introduction of Stamicarbon's Urea
2000plusTM
in 1996, was yet another milestone. By combining equipment, our engineers
have been able to reduce the number of high pressure vessels in the process, thereby also
simplifying the overall design, piping and construction.
The result: a considerable lowering of investments and operating costs.The Pool
Condenser concept was the first step in the development of this technology. A second
step was the introduction of the Urea 2000plus TM
Pool Reactor concept, which has been
built at DSM in Geleen, The Netherlands, with a capacity of 1150 mt/d.
Stamicarbon can offer this process in its pool condenser alternative in single train
capacities up to 3,250 mt/d. This capacity range again signifies an improvement over
today's plants, which have typically been designed for around 2000 mt/d.
The Pool condenser
In the effort to develop the pool condenser, use was made of extensive experience gained
in urea plants of our licensees in which similar condensers are used for different purposes
and from the extensive process database available at Stamicarbon.
Basically, the pool condenser is a horizontal vessel with a submerged U-tube bundle. It is
fabricated from carbon steel with internals and lining in stainless steel.
The operating principles are:
Strip-gases are condensed in a pool of liquid on the shell side, with low
pressure steam being generated on the tube side.
Adequate residence time allows the reaction of ammonium carbamate to
urea and water to proceed to up to 60 % of equilibrium.
The condensation temperature on the shell side is high as a result of the
formation of high boiling components (urea and water), resulting in a
higher delta T for the exchanger part. The formation of gas bubbles
ensures a high degree of turbulence and provides a large area for mass
and heat transfer. Both phenomena contribute to a higher heat transfer.
The Optimum Reactor Design
The optimum reactor design curve
indicates that as much as 60% of
the fractional approach to
equilibrium (F.A.E.) is reached
already within the pool condenser
whose capacity is only 30 to 40 %
of the required reaction volume. As
a direct consequence, the actual
reactor volume can be considerable
reduced.
The pool condenser design
Process data: Mechanical design data:
Shell side:
- 140 bar synthesis pressure
- 175 degree C at reactor outlet
Tube side: 4.5 bar steam/BFW
Stainless steel vessel
U-tube bundle
Internal bore welding
Gas dividing system with flow deflector
plates
Tube supports
Advantages
The pool condenser configuration offers the following technological
advantages:
The urea reactor volume is reduced by some 40 %.
The pool condenser requires some 45 % less heat exchange area.
The height of the steel structure is reduced by some 10 meter.
No stress corrosion can take place, because of the absence of crevices
between tube and tube sheet.
The operational flexibility has improved immensely.
The start-up of the synthesis section is very easy.
Operational Experience
The pool condenser is used in the urea plant of
Karnaphulli Fertilizers Company in Chittagong,
Bangladesh. The plant has a design capacity of
1725 mtpd and was constructed by Chiyoda of
Japan. It came on stream in December 1994. The
pool condenser concept was selected for this
plant because of its location in the vicinity of
Chittagong Airport. A low skyline of the plant
was a restricting requirement. The pool
condenser allowed the reactor to be made
considerably shorter because the compensating
reactor volume is available in the shell side of the
horizontal carbamate condenser.
In the 4 years of operation this pool condenser
plant is performing on a higher than design load
in a very reliable way.
The 1725 mtpd KAFCO urea
plant with the Pool Condenser,
in operation since December
1994.
Technology for the next century
Technology can always be improved. Stamicarbon has again demonstrated that
mature technology can still be innovated. A major development resulting from
the successful performance of the pool condenser in Bangladesh is the
incorporation of all the required retention time for the urea reaction in one and
the same vessel, so creating the new Urea 2000plusTM Pool Reactor process in
1996. The first Pool Reactor plant with a capacity of 1150 mtpd is in operation
since March 1998 at DSM in Geleen, The Netherlands. The operational
experiences since then are magnificent.
Another large pool condenser is presently under design for the revamp of the
conventional PIC Kuwait plant, tripling the original capacity and at the same
time reducing the steam requirement significantly.
Stamicarbon's objective is to remain the world leader in urea technology. With
our Urea 2000plusTM technology we can license state-of-the art urea plants with
capacities far above 2000 mtpd for dependable service far beyond the year
2000.
Producers opting for Urea 2000plusTM technology will be ready for the
challenges of the future.
For further information see:
CO2 Stripping urea process
Urea 2000plusTM Technology
Urea 2000plusTM Pool Reactor technology
References Urea 2000plusTM
References CO2 Stripping 1990-1999
Revamping
Plant Inspection and Equipment Procurement Services