Ejector pumps are used for drawing-in (pumping), thrusting and transport of all types of liquids, emulsions and suspensions. Pumped and drawn-in liquids can contain gases (air, methane, carbon dioxide etc) and un-dissolved solid grains and pieces of material of different origin and size.

They are used for performing a series of different operations in many fields (industry, construction, waterpower engineering, mining etc.).

Depending on the type of driving fluid they are divided into:

  • ejector hydro pumps (liquid-liquid)
  • ejector gas pumps (gas-liquid)
  • ejector vapor pumps (vapor-liquid)

1.1 1.1 Ejector hydro pumps (liquid-liquid)

A liquid (most often water) is used as the driving fluid in these pumps. These pumps are widely applied in many fields: for small and large flows (from several l/h to several thousand m3/h), for low and high output pressures (from minimal to > 20 bar), for low and high temperatures, for pumping water from great depths (depths greater than 500 m), for pumping (drawing in) and thrusting liquid with mechanical admixtures of different sizes and origin (see ejector hydro-transport), for pumping (drawing-in) liquid that contain gases, for increasing pumping-in heights of other pumps, for preventing pump cavitation, for transport of warm liquids, for pumping-in and thrusting acid, alkaline and other chemical liquids, emulsions and suspensions with different concentrations and compositions, for performing chemical reactions and other special and individual applications.

dimenzije_ejektorFigure 1 Sketch of an ejector with dimensions
pumpe02Figure 1.1a Fluid parameters

Q1, Q2 i Q3 – volume flow in (m3/s) or (m3/h),
r1, r2 i r3 – density in (kg/m3),
p1, p2, i p3 – pressure in (bar), recommended in (baraps)

Index 1 denotes the driving fluid entering the ejector, index 2 the drawn-in liquid at the ejector input and index 3 denotes a mixture of driving fluid and drawn-in liquid at the ejector output

Size Max. flow
Q3 (kg/h)
Attachments
DN
Dimension
(mm)
A B C a b c
1 1200 20 20 20 40 80 150
2 3500 25 20 32 60 85 270
3 6000 32 25 40 65 100 350
4 12000 40 32 50 70 115 410
5 24000 50 40 65 80 125 480
6 32000 65 40 65 80 125 480
7 40000 65 50 80 80 125 530
8 70000 80 65 100 115 135 730
9 100000 100 80 125 150 165 950

Ejectors are produced with flanges, a threaded fastener and attachments for connecting with rubber or plastic tubes.

When ordering an ejector the following data needs to be given:

  • density r1and r2 in (kg/m3),
  • mass flow m1 and m2 or at least one of them in kg/s or kg/h or volume flow Q1 and Q2 or at least of them in m3/s or m3/h,
  • of the three pressures p1, p2 and p3 two must be set (bar or barabs),
  • if all three pressures are set than only one mass or volume flow can be set (see figure 1 and 1a).

Example 1.1

Data: The pumped water has a flow of m2=12.4 t/h, density r2=1.2 t/m3, pressure p2=1.2 barabs (the ejector is set 2 m below the level of the pumped liquid). The driving liquid has a flow of m1=20 t/h and density r1=1 t/m3. The pressure required at the ejector output p3=2.5 barabs. The pressure of the driving liquid p1 needs to be determined.

Solution: for m = m2/m1=12,4/20 = 0,62 and r2/r =1,2/1=1,2

From the diagram one can read y = 0,305 and h = 0,24.

p1 = p2 + (p3 – p2) / y =1,2 + (2,5 –1,2) / 0,31 = 5,4 baraps (4,4 bar)

Example 1.2

All data is the same as in example 1.1 only the ejector is placed 2 m above the pumped liquid level i.e. the pumped water pressure at the ejector input is p2=0.8 barabs (0.2 bar vacuum).

Solution: for m = 0,62; r2/r =1,2, and for y = 0,305 the required driving liquid pressure is

p1 = p2+ (p3 – p2) / y = 0,8 + (2,5 – 0,8) / 0,31 = 6,28 baraps (5,28 bar)

The utilization coefficient is the same as in example 1.1 h = 0,24.

pumpe03
m = m2/m1(kgsunctioned liquid /kgdriving liquid)
pumpe04
Figure 1.2 Variants for pump and ejector connection
pumpe05
Figure 1.3 Ejector transport of dirty and muddy liquids