2000 Hook-up Book - Spirax Sarco

SYSTEM DESIGN
28
Temperature Control Valves for Steam Service
Steam Injector
Unlike a sparge pipe, a steam
injector is a manufactured device
that draws in the cold liquid,
mixes it with steam within the
injector nozzle and distributes the
hot liquid throughout the tank.
Fine steam filtration in the preparation of cheese production is
important to the quality of the final product. Because the producer
of cheese products was heating cheese vat washdown
water by direct steam injection, a filtration device was added
to enhance product quality by filtering out the particulates.
While pleased with this simple method of heating, there
was some concern that any particulates entering the washdown
water during steam injection may ultimately contaminate
the vats being cleaned, affecting the cheese production.
Solution
Direct steam injection was the best solution for the cheese
producer, but the concern about the contamination was
very important.
• A separator was installed in the incoming steam supply
line, which removes a high percentage of the entrained
moisture. A fine mesh screen strainer was installed to
remove solid particulate matter.
• A pneumatically actuated two port valve was installed to
control tank temperature. The unit throttles the flow of
steam to the tank based on the signal being transmitted
by the temperature controller.
• Having removed the entrained moisture and majority of particulate
matter from the steam supply, a cleanable CSF16
The circulation induced by the
injector will help ensure thorough
mixing and avoid temperature
stratification. See Fig. II-43 (page
105) for a typical injector installation.
Other advantages of the
Case in Action: Cheese Production
Temperature Control Valves for Liquid Service
Temperature control valves for liquid
service can be divided into
two groups. Normally associated
with cooling, these valves can
also be used on hot water.
Direct Operated Valves
Three types are available for liquid
service and a selection would
be made from one of the following
styles.
2-Port Direct-Acting.
Normally open valve that the thermal
system will close on rising
temperature and used primarily
for heating applications.
2-Port Reverse-Acting.
Normally closed valve which is
opened on rising temperature.
For use as a cooling control,
valve should contain a continuous
bypass bleed to prevent stagnate
flow at sensor.
3-Port Piston-Balanced.
This valve is piped either for
hot/cold mixing or for diverting
flow between two branch lines.
Pneumatically Operated
Valves
As with direct operated valves,
the pneumatically operated types
have the same three groups. The
major difference is they require
an external pneumatic or electric
(through a positioner or converter)
signal from a controller.
Heating And Cooling Loads
Formulas for calculating the heating
or cooling load in gallons per
minute of water are:
Heating Applications:
a. Heating water with water
Heating water GPM required
= GPM (Load) x TR
∆T 1
injector over a sparge pipe is
reduced noise levels and the ability
to use high pressure steam up
to 200 psig. Refer to applicable
technical information sheets for
sizing and selection information.
stainless steel steam filter was installed which is capable of
removing finer particles smaller than 5 microns in size.
• A vacuum breaker was added to the system in order to
prevent any of the heated water being drawn back up
into the filter during certain periods of operation.
• A stainless steel injector system was installed which is
capable of efficiently mixing large volumes of high
pressure steam with the tank contents with little noise or
tank vibration. (The customer stipulated the reduction of
noise levels in the production facility.)
Benefits:
• Guaranteed steam purity and assured compliance with
the 3-A Industry Standard
• Inexpensive installation compared with alternative heat
exchanger packages available
• Cleanable filter element for reduced operating costs
(replacement element and labor costs).
• Accurate temperature control using components of the
existing system
• Quiet and efficient mixing of the steam and the tank contents
• Product contamination is minimized, the cost of which
could be many thousands of dollars, loss of production
or even consumer dissatisfaction.
b. Heating oil with water
Heating water GPM required
= GPM (Load) x TR
2 X ∆T 1
c. Heating air with water
Heating water GPM required
= CFM x TR
400 x ∆T 1
Cooling Applications:
d. Cooling air compressor
jacket with water
Cooling Water GPM required
= 42.5 x HP per Cylinder
8.3 x ∆T 2
Where:
GPM = Gallons per minute water
TR = Temperature rise of
heated fluid, °F
CFM = Cubic feet per minute Air
∆T 1 = Temperature drop of
heating water, °F
∆T 2 = Temperature rise of
cooling water, °F