Northeast Controls Inc. · Eductors – Jet Pumps
Eductors for Heating Liquids
Steam Condensation Heaters · Models MLE, MLH & ULJ · 100% Thermal Efficiency · No Moving Parts
Eductor liquid heaters heat process liquids by condensing steam directly into the liquid stream — with no heat exchanger, no moving parts, and no electrical connections. The process is 100% thermally efficient: every BTU in the steam is transferred to the liquid as the steam condenses. The condensate becomes part of the heated liquid stream.
Heating eductors operate on the same venturi principle as liquid eductors — a high-velocity motive liquid jet creates a low-pressure zone that draws in the suction fluid. In heating service, the suction fluid is steam. Because of steam's strong affinity for cold water, a greater volume of steam is entrained compared to other gas-liquid combinations. In some cases, the BTUs released during condensation allow the discharge pressure to exceed both the motive and suction pressures.
Three connections are common to all heating eductors: the motive connection (liquid inlet under pressure), the suction connection (steam inlet), and the discharge connection (heated liquid outlet). The motive liquid is diluted by the steam condensate at the discharge.
How a Heating Eductor Works
Motive Liquid Enters
Cold or warm process liquid (the motive fluid) enters the eductor under pressure through the motive connection. The liquid is accelerated through the converging nozzle, creating a high-velocity jet that produces a low-pressure zone in the suction chamber.
Steam Is Drawn In
The low-pressure zone draws steam in through the suction connection. Because of steam's strong affinity for cold water, a greater volume of steam is entrained compared to other gas-liquid combinations. The steam and liquid begin to mix in the throat.
Condensation & Heat Transfer
Steam condenses directly into the motive liquid in the mixing tube. This condensation releases the full latent heat of vaporization — the BTUs in the steam — directly into the liquid. The process is 100% thermally efficient: all BTUs in the steam are transferred to the liquid.
Heated Liquid Discharges
The heated mixture (original motive liquid + steam condensate) passes through the diverging diffuser, which recovers pressure. In some cases, because of the BTUs released during condensation, the discharge pressure can exceed both the motive and suction pressures. The heated liquid exits through the discharge connection.
Key Thermal Principle
Steam carries two forms of heat: sensible heat (related to temperature) and latent heat of vaporization (the energy required to convert liquid water to steam). When steam condenses into liquid, it releases both forms of heat directly into the liquid. This is why heating eductors are 100% thermally efficient — there is no intermediate surface, no fouling resistance, and no heat loss to the environment. A 15 PSIG steam supply (250°F) carries approximately 945 BTU/lb of latent heat plus sensible heat, all of which transfers directly to the process liquid.
Heating Eductor Model Series
Three model series cover in-line and submerged heating applications across a wide range of steam pressures and heating capacities.
Performance
Description
The MLE is the standard in-line heating eductor. The extended mixing tube provides additional contact time between the steam suction and the cold motive liquid, ensuring complete condensation and maximum BTU transfer. Suitable for most open-tank and pipeline heating applications.
Typical Applications
- →Open-tank liquid heating
- →Pipeline heating of process fluids
- →Plating bath temperature control
- →Chemical process heating
Performance
Description
The MLH is designed for high-capacity heating applications where large volumes of liquid must be heated rapidly. The larger throat and mixing tube diameter accommodates higher steam entrainment ratios, making it ideal for industrial batch heating and large-volume process tanks.
Typical Applications
- →Large-volume batch heating
- →Industrial process tanks
- →Wash and rinse tank heating
- →Food processing and CIP systems
Performance
Description
The ULJ is a submerged-discharge heating eductor designed to be mounted at the bottom or side of a tank. Steam is drawn in through the suction port and condensed directly into the tank liquid. The submerged discharge eliminates noise and splashing associated with above-liquid heating.
Typical Applications
- →Quiet, splash-free tank heating
- →Electroplating and anodizing baths
- →Dyeing and finishing tanks
- →Pharmaceutical process vessels
Model Performance Comparison
| Description | Model MLE | Model MLH | Model ULJ |
|---|---|---|---|
| Motive Fluid | Liquid (water/process) | Liquid (water/process) | Liquid (water/process) |
| Suction Fluid | Steam | Steam | Steam |
| Motive Pressure | 15–150 PSIG | 20–200 PSIG | 15–100 PSIG |
| Discharge Temp | Up to 250°F | Up to 212°F | Up to 212°F |
| Discharge Type | In-line | In-line | Submerged |
| Noise Level | Low | Low | Very Low (submerged) |
| Condensate Dilution | Yes | Yes | Yes |
Advantages of Heating Eductors
100% Thermal Efficiency
Steam condenses directly into the liquid being heated. Every BTU in the steam is transferred to the process liquid — no heat exchanger losses, no stack losses, no radiation losses.
No Moving Parts
No impellers, no seals, no bearings, no lubrication. Heating eductors are inherently maintenance-free and have an indefinite service life in clean service.
No Electrical Connection Required
Operates entirely on steam and liquid pressure. Safe for hazardous areas, wet environments, and locations where electrical equipment is undesirable.
Instantaneous Response
Steam condensation is instantaneous. Temperature response is immediate — no warm-up time, no thermal lag. Ideal for processes requiring precise temperature control.
Silent Operation
Condensation of steam into liquid is a quiet process. Submerged models (ULJ) are virtually silent. No hammering, no water hammer, no cavitation noise.
Compact & Easy to Install
In-line models install directly in the pipe. Submerged models mount through the tank wall or bottom. No foundations, no supports, no special installation requirements.
Self-Regulating
As the liquid temperature approaches the steam temperature, the driving force for condensation decreases and steam entrainment naturally reduces. The system is inherently self-limiting.
Wide Material Selection
Available in bronze, stainless steel, carbon steel, Hastelloy, PVC, and other materials to match the process liquid and steam conditions.
Applications by Industry
Heating eductors are used wherever steam is available and a liquid must be heated — from small plating tanks to large industrial process vessels.
| Industry | Typical Uses |
|---|---|
| Electroplating & Metal Finishing | Plating bath heating, anodizing tank heating, rinse tank heating, chromate conversion baths |
| Chemical Processing | Reactor heating, solvent heating, acid/alkali process heating, crystallization vessel heating |
| Food & Beverage | CIP (clean-in-place) heating, pasteurization, blanching, tank heating for syrups and sauces |
| Pharmaceutical | Process vessel heating, WFI heating, CIP/SIP systems, API process heating |
| Pulp & Paper | White water heating, black liquor heating, process tank heating |
| Textile & Dyeing | Dye bath heating, finishing bath temperature control, wash tank heating |
| Water Treatment | Sludge heating, digester heating, process water heating |
| General Industrial | Wash tank heating, degreasing tank heating, parts cleaning, general process heating |
Materials of Construction
Material selection is driven by the process liquid chemistry, temperature, and steam pressure. All metallic units are full ANSI rated.
Bronze
Standard for steam and water service. Most economical.
Carbon Steel
For higher pressures and temperatures.
316 Stainless Steel
For corrosive process liquids, food/pharma service.
304 Stainless Steel
General corrosion resistance at lower cost.
Alloy 20
For sulfuric acid and aggressive chemical service.
Hastelloy C
For extremely aggressive chemical environments.
PVC / CPVC
For corrosive chemical baths (plating, anodizing).
Polypropylene
For aggressive acid and alkali process liquids.
Important: Condensate Dilution
Because steam condenses directly into the motive liquid, the discharge stream is a mixture of the original motive liquid and the steam condensate. The condensate adds volume to the heated liquid. In open-tank applications, this is typically not a concern — the tank level rises slightly as the liquid heats. In closed-loop or concentration-sensitive applications, the condensate dilution must be accounted for in the process design. Contact our engineering team for guidance on condensate balance calculations.
Sizing a Heating Eductor — What We Need
Accurate sizing requires process data. Provide the following on the Jet Pump Application Sheet for a detailed sizing calculation and model recommendation:
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1+201-419-6111 · [email protected]
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