Technical Bulletin B – 900.
901 Series 900,901
Desuperheater
Application
Save fuel with optimized process control. In a situation where the controlled outlet temperature
is higher than the saturation temperature and steam is to be used for heating application. It is
absolutely necessary that for such applications the outlet steam temperature should be as close
as possible to its saturation temperature. The sole reason for this is the saturated steam is the
best conductor of heat and as the degree of Superheat increases, the heat transfers become
inefficient. Superheated steam contains a large amount of heat energy, this energy is in three
forms; 25% of enthalpy of water, 66% of enthalpy of evaporation (latent heat) and 9% of
enthalpy of superheat. The coefficient of heat transfer when using superheated steam as the
heating medium is variable, low and difficult to quantify accurately. This makes accurate sizing
and control of heat transfer equipment difficult, and will also result in a larger and more
expensive heat exchanger. KOMOTO’s desuperheater can help you to optimize your process
control can save fuel and in turn save investment cost.
Desuperheating
To ensure temperature stability of the conditioned steam and to prevent thermal shock in
downstream lines, the cooling water should ideally be fully atomized. There should also be a
correct mix of superheated steam and cooling water.
KOMOTO
1
www.komoto.co.kr
1. Angle Type Desuperheater - Model No. 900
KOMOTO venture desuperheater makes cooling water enters through a special streamlined
spray nozzle. On the surface of this special spray nozzle a thin film of water will be created. The
dynamic energy of the steam flow breaks the surface tension of the film, creating a conical
shaped spray of atomized water. Ideal mixing is achieved by high steam flow turbulence, caused
by the interaction of the venturi effect and the special shaped spray nozzle. Fast and total
evaporation of the cooling water is now accomplished which means that rapid adjustments are
possible, and also avoiding the need for any protective liners in downstream
piping. .
Advantages
● Custom designing
For any size, standard or range.
● Simple installation
In any position, short straight pipe runs. Limited control loops.
● Easy maintenance
No moving parts, no pipe liners and no welding in the construction. Large spray apertures avoids
the spray nozzle becoming choked.
● Energy saving
No need for water supply pressure significantly higher than operational steam pressure and no need
for atomizing steam.
● Large desuperheating range
It is possible to handle extremely large differences in enthalpy between inlet an outlet steam flows.
KOMOTO
2
www.komoto.co.kr
Technical Data
● Size: Steam 1½”to 50”
Water 1½”to 2”
● Forged/Casting construction
● Venturi nozzle type
● Low pressure loss over the desuperheater station
● Water pressure marginally above steam pressure
Materials of Construction
● ASTM SA 105, SA 182F11 or SA 182 F22F (Forged)
● ASTM A217 Gr WC6 (Casting)
● DIN C22.8, 1.7335 or 1.7380
● Other materials upon request
Applicable Codes
● ASME / ANSI B16.34 class 150 to 2500
● DIN 2401 class PN 25 to 400
● Butt-weld connections to ANSI B16.25 or DIN 2559
KOMOTO
3
www.komoto.co.kr
2.Angle Type Desuperheater - Model No. 900
Variable Multiple nozzle spray type desuperheater regulates the amount of injection water
by varying the number of injection nozzles in operation. Control of nozzle opening is
achieved by the positioning of a piston that is operated directly by an actuator mounted on
the valve. This simple design means no separate water injection control.
This feature enables the desuperheater to be a wide range of Cv values which is
customized to specific requirements.
Advantages
● No steam side pressure drop
A negligible steam side pressure drop makes this type
suitable for those applications where steam side pressure
drop is limited, as in turbine exhausts.
● No need for a separate water control water
Due to an integrated and directly actuated water injection
control valve no separated valve is required.
● High-tech nozzles
The spray nozzles, equipped with a special designed
swirl disk, are constructed using the most up to date
technology available, resulting in a fine symmetrical
hollow cone spray.
● Reliability
Injection spray nozzles are sealed by a vacuum
brazing process, maintaining the integrity of these
components under the most extreme conditions.
KOMOTO
4
www.komoto.co.kr
Reference Dimensions
Inlet Size OutletSize Steam Line ∅ A B C D E F H
(Water Side) (Steam Side)
Inches Inches inches mm mm mm mm mm mm mm
6‐12 315 378
8‐12 330
394
1‐1.1/2 3 46‐16 290 355 200 70
10‐14 360
436
16‐18 410
12‐22 450
362 533
24 475
1.1/2 4
14‐22 465
350 557
24‐26 500
250 95
12‐22 450
362 533
24 414 633 475
2" 4
14‐22 465
350 557
24‐26 500
16‐26 530
630
28 555
2" 6
20‐28 560
680
30‐32 610
470 300 140
16‐26 530
630
28 555
3" 6
20‐28 560
680
30‐32 610
Note: Dimensions may be subject to change without prior notification.
Reference only. Please contact KOMOTO for detail dimension.
KOMOTO
5
www.komoto.co.kr
3. Angle Type Desuperheater - Model No. 900
KOMOTO’s mechanical fixed
nozzle type of desuperheater is
designed primarily for use in low
capacity superheated steam
systems where the load is fairly
constant. Mostly hollow cone
nozzles are used where the water is
brought into a twist by a special
geometry of the nozzles and the
pressure difference between the
steam and water. The water is
circularly atomized by the
centrifugal force into fine droplets.
The design provides a simple, cost
conscious but effective method of
steam temperature control. Radial
desuperheaters for large water
loads are available.
Flange connections
3” Class 900 4” Class 900
Class 1500 Class 1500
Class 2500 Class 2500
Steam
DN80- PN 160 DN100- PN 160
flange
PN 250 PN 250
PN 320 PN 320
PN 400 PN 400
1” - 1½” 1½” – 2” – 3”
Water DN 25-40 DN 40–50–80
flange Pressure classes as per Pressure classes as per
Water data requirements Water data requirements
Applicable Codes
● ASME / ANSI B16.34 class 150 to 2500
● DIN 2401 class PN 25 to 400
● Butt-weld connections to ANSI B16.25 or DIN 2559
KOMOTO
6
www.komoto.co.kr
4. Angle Type Desuperheater - Model No. 900
KOMOTO’s steam atomizing type of
desuperheater is designed for high steam
turndown situation and Desuperheating
close to saturation temperature at minimal
loads. A steam atomizing nozzle allows a
small amount of steam (1~2 mass% of the
main steam flow is recommended) to enter
the nozzle upstream of the cooling water.
The atomizing steam breaks up the cooling
water and provides decent quality of water
drop for better evaporation.
Typical configuration of Steam Atomizing Type Desuperheater
KOMOTO
7
www.komoto.co.kr
Typical dimensional drawing Jacket Desuperheater – Model No. 901
Unit : mm
Size A B C D C+D
4" X 12" 300 100 380 300 680
6" X 14" 350 150 550 470 1020
8" X 16" 400 200 700 600 1300
10" X 18" 450 250 850 750 1600
12" X 20" 500 300 1100 940 2010
KOMOTO
8
www.komoto.co.kr
■ Straight Pipe Run
1. Upstream pipe straight run
The upstream straight run is to ensure that the steam is in consistent and homogeneous state
and not swirling or cork-screwing when the spray water is injected. It is usually recommended as
typically 5 steam pipe diameters or 1.5 meter which is bigger.
2. Downstream pipe straight run
The downstream straight run is to ensure that the water droplets have evaporated before coming
into contact with an elbow and becoming recombined into a pool of water. Pipe should be
straight, free of bends and contain no restrictions. We recommend a minimum straight length
distance of 2.5 to 7.5 m depending on the amount of residual superheat required (specified in
table below). The greater the amount of residual superheat required, the faster the water
droplets are evaporated and the shorter the distance required.
■ Temperature Sensor Pipe Length Requirements
If the water has not completely vaporized, the resulting input control data will be inaccurate due
to moisture contacting the sensing temperature element. We recommend a minimum distance
from the desuperheater to the temperature sensor to be 12m to 17m, but it should be at least
7.5m with thermowell sleeve.
KOMOTO
9
www.komoto.co.kr
■ Thermowell sleeve
The temperature sensor protection is recommended whenever the distance to the injection
point is close to the minimum value and whenever one or more bends are present between
water injection point and temperature sensor.
Such a layout in fact can produce separation of atomized water generating droplets that can hit
thermometer well affecting measured temperature value. Minimum upstream piping length shall
be not less than 6 DN. The protection may be manufactured as shown below and its purpose is
to avoid sensor wetting by not evaporated water.
Thermowell sleeve < 1. Thermowell 2. Sleeve 3. Pipe wall >
■ Set point of temperature controller
There is a need for controlling the steam temperature as close to saturation as possible. The
inherent problem with this is that the closer the temperature gets to saturation the more likely
the steam flow will have residual water droplets. This is due to the fact that the temperature
profile of a steam flow is uneven, often with cooler temperatures in the center and
progressively hotter temperatures moving outwards. The set point is recommended to be not
less than 6 DegC above the steam saturation point. Very minimum possible set point is shown
in the above ‘Comparison of desuperheater types’ table.
KOMOTO
10
www.komoto.co.kr
■ Strainer
In order to protect both the cooling water and steam valves as well as to prevent the small
bores within the Desuperheater from becoming blocked, installing strainers in BFW line is
required. KOMOTO requests a strainer with a mesh size of approx.. 100 µm in the water
supply line to project desuperheater from clogging.
■ Nozzle Capacity
Size Nozzle No. Capacity Nozzle No. Capacity
6A Cv = 0.075 9A Cv = 0.112
6B Cv = 0.158 9B Cv = 0.238
½”(16mm)
6C Cv = 0.300 9C Cv = 0.451
6D Cv = 0.586 9D Cv = 0.879
6Dx Cv = 1.160 9Dx Cv = 1.740
6E Cv = 1.902 9E Cv = 2.853
6F Cv = 2.839 9F Cv = 4.259
1”(25mm)
6G Cv = 6.032 9G Cv = 9.048
6H Cv = 9.396 9H Cv = 14.094
6K Cv = 13.488 9K Cv = 20.232
Cv can be customized for the optimize performance
Korea : KOREA MOTOYAMA INC. Japan : MOTOYAMA INC.
29, Hagunsandan 1-Ro, Yangchon-Eup, Gimpo-Si, 14-26, 1-Chome, Haginaka, Ohtaku, Tokyo, Japan
Gyeonggi-Do,Korea Tel : 81-3-3732-3696
Tel : 82-31-996-5252 Fax : 82-31-996-2992 Fax : 81-3-3738-9371
E-mail : info@komoto.co.kr
Web : http://www.komoto.co.kr
KOMOTO
11
www.komoto.co.kr
