Steam injectors - Filter

Steam injectors

Steam in
2
Steam injectors for boiler feedtank, hot water
and other industrial process
heating requirements.
Cold water drawn
in through radial
ports.
IN40M shown
Hot water out
Vigorous mixing of steam
and water takes place
inside the nozzle ensuring
quiet operation.
Spirax Sarco steam injectors use steam to raise the temperature of water or other liquids. The injector draws in
cold liquid, mixes it with steam inside the injector and distributes the heated liquid in the tank. In many applications
the circulation induced by the injector is an advantage ensuring thorough mixing and avoiding temperature
stratification.
Boiler feedtank applications
Dissolved oxygen must be removed from boiler feedwater if corrosion is to be prevented in the boiler. Oxygen
can be removed either by chemicals or by heating. The dissolved oxygen content of water at 20°C is 9 ppm,
at 60°C is 5 ppm and at 90°C is just under 2 ppm.
By heating the boiler feedwater to typically 85 - 90°C to remove most of the oxygen, and introducing an oxygen
scavenging chemical into the boiler feedline to remove the small quantity of remaining oxygen, chemical usage
can be minimised. Additionally, boiler efficiency may be increased since blowdown requirements may be lowered.
Fitting
The injectors can be fitted to the steam supply pipework or installed directly onto the tank wall using a female
threaded connection. For very large installations, multiple injectors may be used.
Range Nominal size End connections
IN15 15 mm Screwed BSP or NPT
IN25M 25 mm Butt weld, screwed BSP or NPT
IN40M 40 mm Butt weld, screwed BSP or NPT

Typical injector systems - examples
A typical electropneumatic system and a self-acting control system are shown below. Self-acting controls offer
an economical solution for boiler feedtank applications. Pneumatic or electric systems can offer close temperature
control for process applications. Pipework can be routed inside or outside the tanks. Your local sales engineer
will be pleased to advise on the most suitable system for your plant requirements.
Steam in
Steam in
Stop valve
Stop valve
Control valve
Y-type
strainer
Controller
Electropneumatic control system
Y-type
strainer
Vacuum breaker
Dial
thermometer
Vacuum
breaker
Dial
thermometer
Control
valve
Selecting a system
Spirax Sarco offers a wide range of valves,
controllers, sensors and ancillary equipment for
pneumatic, electric and self-acting control systems.
Literature describing these products is available on
request. The optimum choice of an efficient and
economical steam injection system depends on
many factors including temperature, steam flow,
heating times and tank volume.
Your local Sales Engineer will be pleased to advise
on the most suitable equipment for your plant.
Temperature
sensor
Control
and sensor
Pocket
Injector
Self-acting control system
Pocket
Injector
User benefits
● Complete mixing of steam within the injector
provides quiet, efficient, and economic heating.
● Reduced need for oxygen scavenging chemicals
in boiler feedwater applications.
● 316 stainless steel injectors for long life and
maintenance free operation.
● Avoids temperature stratification in tanks -
maintains efficiency.
● Flexible control system packages,
to suit individual applications.
IN25M / IN40M
shown
IN15 shown
3

4
Capacity
Steam injector capacities when heating tanks of up to 3 metres
deep and vented to atmospheric pressure. The choice of control
valve can affect the steam capacity:
Injector type IN15 IN25M IN40M
Steam pressure at Saturated steam
inlet of injector (bar g) capacity kg / h
1 20 135 400
2 48 175 580
3 66 280 805
4 84 350 970
5 102 410 1 125
6 120 500 1 295
7 138 580 1 445
8 156 640 1 620
9 174 700 1 820
10 192 765 1 950
11 210 830 2 250
12 228 900 2 370
13 246 975 2 595
14 264 1 045 2 710
15 282 1 095 2 815
16 300 1 170 3 065
17 318 1 225 3 200
Intermediate values may be obtained by linear interpolation.
For higher capacities use two or more injectors in parallel. The
information given is empirical and must not be used for critical
applications.
Dimensions (approx.) in millimetres
Injector type A B C Weight (kg)
IN15 ½" 205 28 0.4
IN25M 1" 84 71 0.8
IN40M 1½" 115 88 1.6
1" BSP Taper or NPT male
IN15 A C
BSP / NPT
female
B
IN25M
IN40M
A
B
Limiting conditions
Body design rating PN25
Maximum saturated steam conditions:
17.0 bar g / 207°C
C
Some of the products may not be available in certain markets.
Kv values
IN15 - Kv 1.55 IN25M - Kv 9.2 IN40M - Kv 14.5
For conversion Cv (UK) = Kv x 0.97 Cv (US) = Kv x 1.17
Tank contents kg (litre) or Boiler feedwater flowrate kg/ h
Estimating steam
flowrates for water heating
The following chart enables an estimate to be made of the steam flowrate
required to heat up a tank in one hour or to produce a particular temperature
rise in a boiler feedtank.
For boiler feedtanks note that feedwater flowrate equals steam generation
rate plus blowdown rate.
Injected steam rate lb/ h
100 000
70 000
200 300 500 1 000 2 000 5 000 10 000 20 000
200 000
50 000
100 000
30 000
20 000
70 000
50 000
30 000
20 000
10 000
7 000
5 000
3 000
2 000
Water temperature rise
1 000
700
10 000
7 000
5 000
3 000
2 000
500
1 000
300
50 70 100 200 300 500 1 000 2 000
700
5 000 10 000
Injected steam rate kg/ h
Example 1
Example
1. 'My tank size is 1.5 m x 2 m x 1.5 m.
I want to heat it from 20°C to 40°C in one hour'. Assume the tank is full.
The tank volume = 4.5 m³ = 4 500 litre (4 500 kg).
From the graph the required injected steam rate = 155 kg/ h.
2. 'My tank is the same as example 1, but I want to heat it in
20 minutes'. Since it is required to heat it up 3 times faster, then
the injected steam rate will be three time as great i.e. 465 kg/ h.
3. 'I want to heat up my boiler hotwell from 30°C to 90°C, I have
two boilers steaming all year round. They are each generating
a maximum of 10 000 lb/ h and my blowdown rate is 5 %'.
Total steam generation rate = 20 000 lb/ h.
Total blowdown rate = 5 % of 20 000 = 1 000 lb/ h, hence
feedwater flowrate = 20 000 + 1 000 = 21 000 lb/ h.
From the graph the required injected steam rate = 1 000 kg/ h
10°C
20°C
Example 3
Materials
Systems
30°C
50°C
80°C
Austenitic stainless steel 316L
Tank contents lb or Boiler feedwater flowrate lb/ h
(Imperial gallon = 10 lb)
Fully engineered systems are available from Spirax Sarco
including controllers, valves and other ancillary products.
How to specify
1 - Spirax Sarco steam injector type IN25M screwed 1" BSP
in 316L grade stainless steel.
Spirax-Sarco Limited, Charlton House,
Cheltenham, Gloucestershire, GL53 8ER UK.
Tel: +44 (0)1242 521361 Fax: +44 (0)1242 573342
E-mail: Enquiries@SpiraxSarco.com
Internet: www.SpiraxSarco.com
© Copyright 2000 Spirax Sarco is a registered trademark of Spirax-Sarco Limited
SB-P401-02 AB Issue 5
INS