Steam Condensate Load Heating Systems

Reference data and engineering information about steam condensate load heating systems for piping systems applications.

steamcondensateloadheatingCalculator

Overview

In steam-heated systems, the condensate load represents the mass of steam that must be supplied (and subsequently condensed) to meet a process heating requirement. Two fundamental scenarios arise in practice:

Heat transfer through a surface — steam condenses on one side of a heat exchanger, transferring energy to a fluid or gas on the other side.
Heating a batch of material — steam energy raises the temperature of a product from an initial state to a target state.

In both cases the required condensate load is determined by dividing the total heat demand by the latent heat of the steam supply.

Key Formulas

Heat Transfer Through an Area

$Q = U \cdot A \cdot \Delta t$

Total heat transferred through a surface of area $A$ , with overall heat transfer coefficient $U$ and mean temperature difference $\Delta t$ between the steam and the secondary fluid.

Heating a Material (Batch)

$Q = m \cdot c_p \cdot (t_2 - t_1)$

Total heat needed to raise a mass $m$ of material (specific heat $c_p$ ) from temperature $t_1$ to $t_2$ .

Condensate Load

Once the total heat $Q$ and the process time $h$ are known, the heat rate and condensate mass flow follow directly:

$\dot{Q} = \frac{Q}{h}$

$\dot{m}_{cond} = \frac{\dot{Q}}{L}$

where $L$ is the latent heat of condensation for the steam supply pressure and $h$ is the available heating time.

Variables

Symbol	Description	Unit
$Q$	Quantity of heat transferred	kJ
$\dot{Q}$	Heat rate	kW
$U$	Overall heat transfer coefficient	W/(m²·K)
$A$	Heat transfer area	m²
$\Delta t$	Temperature difference (steam to secondary fluid)	K
$m$	Mass of heated material	kg
$c_p$	Specific heat of material	kJ/(kg·K)
$t_1$	Initial material temperature	°C
$t_2$	Final material temperature	°C
$h$	Available heating time	s
$L$	Latent heat of steam condensation	kJ/kg
$\dot{m}_{cond}$	Condensate load (steam mass flow)	kg/s

Reference Data

Latent Heat of Saturated Steam

9 rows

Latent heat of condensation decreases as steam pressure rises.
Gauge Pressure(bar)	Saturation Temp(°C)	Latent Heat(kJ/kg)
0	100	2257
1	120	2201
2	134	2163
3	144	2133
5	159	2085
7	170	2048
10	184	2000
14	198	1952
20	216	1890

Source: engineeringtoolbox.com

Typical Overall Heat Transfer Coefficients (U)

6 rows

U-values vary widely with fouling, velocity, and fluid properties.
Application	U min(W/(m²·K))	U max(W/(m²·K))
Steam to water (shell & tube)	800	1500
Steam to air (finned coil)	25	50
Steam to oil (shell & tube)	100	350
Steam to process liquid (plate HX)	1500	4000
Steam to gas (jacketed vessel)	10	30
Steam to viscous fluid (coil in tank)	100	300

Source: engineeringtoolbox.com

Calculator

Condensate Load From Surface Heating

Condensate Load — Area-Based Heating

Overall heat transfer coefficient(W/(m²·K))

Heat transfer area(m²)

Temperature difference(K)

Latent heat of steam(kJ/kg)

Condensate Load From Batch Heating

Condensate Load — Material Heating

Mass of material(kg)

Specific heat(kJ/(kg·K))

Initial temperature(°C)

Final temperature(°C)

Available time(s)

Latent heat of steam(kJ/kg)

Unit Converter

Steam Condensate Load Unit Converter

Condensate load(kg/h)

Heat rate(kW)

Latent heat(kJ/kg)

Heat transfer area(m2)

Restored Original Source Tables

The following tables are restored from the original source page to preserve the complete reference data.

Engineering Notes

Start-up loads dominate. Heating cold equipment and piping from ambient to operating temperature can require several times the steady-state condensate rate. Size steam mains and traps accordingly.
Flash steam. When high-pressure condensate is discharged to a lower-pressure vessel, a portion flashes back to steam. Flash steam recovery can preheat feed water and reduce total boiler load.
Air and non-condensable gases. Even small concentrations of air dramatically reduce the effective U-value. Install air vents on steam-heated surfaces and ensure proper vent sizing during start-up.
Fouling factors. The U-values in the table above represent clean conditions. Add fouling resistances (typically 0.0001–0.0003 m²·K/W per surface) when sizing exchangers for long service intervals.
Trap sizing. Steam traps must be sized for at least the maximum condensate load including start-up margins, typically 1.5–3× the normal operating load.
Latent heat dependence on pressure. Always use the latent heat corresponding to the actual supply pressure. At higher pressures the latent heat decreases, so more steam mass flow is needed for the same heat duty.

References

Original Source — Engineering ToolBox

Source: engineeringtoolbox.com