Eductors for Heating Liquids

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Eductors for Heating Liquids

heating eductors Eductor liquid heaters operate by condensing steam into the liquid that is being heated. The process ensures a complete transfer of the BTUs in the steam to the liquid. The steam gives up its BTUs as it condenses into the liquid. This also dilutes the motive liquid with the condensate. Eductor liquid heaters function under the normal principles of eductors. In actuality, the process is that of a liquid pumping a gas.

To better understand liquids pumping gases, refer to JRG/JT Technical Guide 700-310. The only thing that differs with pumping steam as a suction fluid is the increased affinity of steam for cold water. Because of this affinity, a greater volume of steam is pumped under the same conditions. Also, in some cases, the BTUs being released allow the unit to discharge to higher pressures than either the motive or the suction pressure.

Operating specifications:

Model	MLE	MLH	ULJ	TLA
Heating Process	In-line	In-line	In-line	In-tank
Max Temp Rise (°F)	180	215	200	125
Maximum Flow Heated (GPM)	5000	5000	700	4000
Steam Press Range (PSIG)	Vac-45	Vac-120	0-150	1-140

Other Steam Heaters:

In Tank Heaters - Fig. TLA

Simplex Heaters - Fig. 340

Continuous Heaters - Fig. 320

Slurry Heaters - Fig. 327

How to Size Eductors for Heating Liquids:

Eductor liquid heaters (also known as heating eductors)have three service connections that will affect the performance of the units. The actual conditions at these connections should be clearly specified to ensure correct operation. The motive is the connection where the liquid to be heated enters the eductor. The heating (steam) is the connection where the steam enters the eductor. The discharge connection is where the heated fluid exits the eductor.

Motive (Liquid) Connection:

At this connection, the liquid to be heated enters the eductor. In most instances, the liquid is under pressure at this point. As it passes through the nozzle, the pressure is converted to a high velocity stream that passes into the heating chamber. The velocity of the motive liquid in the heating chamber allows the steam to be drawn into the liquid to be heated.

Heating (Steam) Connection:

The entrainment of steam into the liquid begins as the high velocity liquid stream draws the gas (steam) into the heating chamber as it passes through the chamber. This lowers the pressure in the heating chamber, allowing more steam to be pushed into this area. As the steam is entrained into the high velocity liquid, its BTUs are released into the fluid, heating the liquid. The resulting mixture is pushed by momentum toward the outlet connection of the eductor.

Outlet Connection:

As the condensed steam and liquid mixture go through the eductor, the energies of the two fluids are combined. This combination and the relative percentage of each fluid will have a great effect on the amount of pressure that can be recovered at the outlet of the eductor. Unlike other eductor applications, the heater generally has a positive power input on both incoming ports. In the case of the liquid motive, this power is from the pressure of the incoming liquid. In the case of the heating steam, this power can come from the pressure of the incoming steam and/or from the internal energy of the steam being released as it condenses. The percentage of each fluid entering the eductor and how both are mixed will determine how much back pressure can be tolerated. In the event of high discharge pressures, the eductor must be started and reach a state of equilibrium before the maximum discharge pressure can be handled. In most cases, this requires the installation of a bypass valve for start up.

Typical Liquid Eductor Heater Units:

Jerguson/Jacoby-Tarbox makes several types of liquid heating eductors that are designed to heat over a variety of conditions. Because of the diversity of applications for the units, the motive and heating ports may be in different locations. It is important for proper operation of the units that the liquid and steam be connected to the proper ports. The following JRG/JT models of eductors can be used in heating applications: ULJ, MLE, and MLH. On all of these units the liquid to be heated enters the motive connection.

Where can Liquid Heating Eductors be Used?

Eductors have been used to successfully heat liquids in many industries and processes. The units can heat in-line or in-tank to achieve results that will improve your process. These units are used in the following industries: Pulp and Paper, Chemical, Petroleum, Dairy, Agriculture, and Breweries. Typical applications include: sterilization, cooking, heated wash down sprays, heating solutions, pasteurization in-line, mixing while heating, activating temperature controlled substances, and maintenance of tempering vessels.

Why are JRG/JT eductors chosen for Heating applications?

Small physical size	Heating done completely within piping systems.
Low cost of installation	Foundations and wiring are not required.
Integral Gage Ports	Enables rapid troubleshooting.
No moving parts	Reduced maintenance.
ASME ANSI B16.5 Rating	Enables ANSI rating of entire systems.
No packing glands	Reduced maintenance.
Lubrication is not required	Reduced maintenance.
Body as strong as piping	Handles normal piping stresses.
Wide variety of connection types available	Male/Female NPT, Butt/Socket Weld, Flanged, Silbraze, Victaulic.
Hex mounting on body	Easy mounting to piping.
Properly installed eductors require few	Ease of control for intermittent operations shutdown procedures.
Economical use of waste steam	Low pressure steam still contains substantial heating value, all of which is used.
Smooth body flow passages	High efficiency and flows.
Use of sources normally considered waste	In many cases, steam can be used for heating with pressures as low as 1 or 2 PSIG. This allows you to gain value from a resource normally vented or returned to your boiler.
0-Ring sealed body/nozzle joint	Bubble tight seal, easy effective maintenance.
Longer service life	The lack of moving parts means many units will operate for years without affecting performance.
Low relative cost for exotic materials	The no moving parts feature makes it easy and quick to obtain exotic materials. These materials will not affect the performance of the units.

How to Size Eductors for In-Line Heating

In-Line Eductor Reference Tables

How to Heat Liquids in Vessels

Tank Eductor Reference Tables

In-Line Eductor Dimensions

More Information on Tank Heaters

Dimensional Drawing for Eductors

Northeast Controls Incorporated

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