How is the cost of steam generation calculated?

The cost of steam is primarily calculated based on the fuel cost required to raise the enthalpy of feedwater to steam, considering the boiler's overall efficiency. A common shortcut method involves calculating the fuel cost per unit of steam and then applying a markup (e.g., 30%) to account for other operational expenses like raw water, treatment, pumping, maintenance, and labor.

What factors influence the overall cost of steam in an industrial plant?

Key factors include the cost of fuel, the enthalpy difference between the steam produced and the boiler feedwater, the boiler's thermal efficiency, and auxiliary costs such as raw water, water treatment chemicals, electricity for pumps and fans, sewer charges, environmental compliance costs, maintenance, and labor. Operational practices like insulation quality and steam trap efficiency also significantly impact the true cost.

Why is it important to optimize steam generation and usage?

Optimizing steam generation and usage is critical because steam generation is a major energy consumer in most process industries, directly impacting operational profitability. By reducing steam losses (e.g., through leaky traps, uninsulated pipes) and recovering energy (e.g., via steam turbines), companies can achieve substantial energy savings, lower operating costs, and reduce their environmental footprint.

Steam cost calculation

What is the cost of steam generation in a factory ?

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1. Steam cost : calculation method

2. Steam generation tips

3. Steam cost Excel calculator

The cost of fuel is on the rise and will stay on long term due to the rarefaction of oil and gas as reserves worldwide are depleted. Process industries however still need such fuels and a common application is to produce steam. Steam will be used in many aspects of the process, as utility (process heating for instance) or as part of the process / formulation.

Steam generation is thus expensive as it is done in boilers running with oil or gas. Being able to track the cost of steam is necessary to make sure that the factory remains profitable. Understanding how much cost steam is also a powerful motivator to look for energy savings (look for leaky steam traps, install steam turbines to recover energy...).

The present page presents a shortcut method to estimate the cost of steam produced in a factory.

1. Steam cost : calculation method

[Hall[ is proposing a shortcut calculation to estimate the cost of steam. It is in 2 steps, 1st calculate the cost of the fuel, 2nd calculate the cost of steam by integrating other factors.

⚠️ ENGINEERING NOTICE & EDUCATIONAL DISCLAIMER: This interactive calculator is provided exclusively for preliminary estimation and educational purposes. It is not intended for detailed design or equipment procurement without certified vendor rating. No warranty, expressed or implied, is provided, and no liability is assumed.

Industrial Steam Cost Calculator

Fuel Cost ($a_F$):

Enthalpy of Steam ($H_s$):

Enthalpy of Feedwater ($h_w$):

Boiler Efficiency ($\eta_B$):

(0-1)

1.1 Step 1 : calculate the cost of fuel

The cost of fuel used for steam generation can be calculated as :

\[C_F = a_F \times \frac{(H_s - h_w)}{(1000 \cdot \eta_B)}\]

Cost of fuel calculation

With :

C_F = cost of fuel ($/1000lb steam generated)
a_F = cost of fuel for the boiler ($/MMBtu)
Hs = enthalpy of steam (Btu/lb)
hw = enthalpy of boiler feedwater (Btu/lb)
η_B = overall boiler efficiency

The typical efficiency of a boiler is around 80%.

1.2 Step 2 : calculate the cost of steam

The cost of steam is mainly coming from the cost of fuel, however there are many other costs to be considered (cost of raw water, treatment of feedwater, pumping/fan power, sewer charges, environmental costs, maintenance and labor...). To take this into account, a 30% markup is put on top of the fuel cost. This is of course an approximation, but is sufficient to get a sense of the overall steam cost. More detailed studies should estimate the cost of each of these other contributors to the steam cost.

\[C_G = C_F \times (1+0.3)\]

C_G = C_F*(1+0.3)

With :

C_G = cost of steam ($/1000lb steam generated)
C_F = cost of fuel ($/1000lb steam generated)

Practical Plant Engineering Rules of Thumb & Safety Limits for Steam Generation:

Boiler Efficiency: Typical industrial boiler efficiency ranges from 75% to 85%. Values outside this range may indicate design issues or require specific justification (e.g., highly optimized systems or older, inefficient units).
Steam System Optimization:
- Approximately 60% of thermal energy use in process plants is for heating purposes via steam. Significant savings can be achieved by optimizing steam usage.
- Energy Recovery: Consider installing a steam turbine for energy recovery if low-pressure steam is available at flow rates > 20,000 kg/h.
- Pressure Reducing Valve (PRV): Steam generated at high pressure and then reduced via a PRV to low pressure typically results in similar overall steam costs to directly generating low-pressure steam, unless energy recovery is implemented.
- Insulation: Proper insulation can prevent up to 90% of heat loss from hot uninsulated pipes. Regular inspection and maintenance of insulation are crucial.
Feedwater Treatment: Essential to prevent scaling and corrosion in boilers, which can severely reduce efficiency and lead to costly downtime. The cost of feedwater treatment should always be factored into overall steam cost.
Steam Trap Management: Leaky or malfunctioning steam traps are a major source of energy loss. Regular surveys and maintenance can yield substantial savings.
Minimum Enthalpy Difference: The difference between steam enthalpy ($H_s$) and feedwater enthalpy ($h_w$) must always be positive, representing the energy added to the water to convert it to steam. A non-positive value indicates an impossible physical scenario.

2. Steam generation tips

In order to optimize further the usage of steam in the factory, please keep in mind the following :

Steam usage in a process plant is mainly for heating purpose (60% of thermal energy use)
When having low pressure steam available, consider using a steam turbine to recover energy, especially if the flow rate of steam is >20000 kg/h
Low pressure steam resulting from using a pressure reducing valve on high pressure steam will result in similar cost of steam in between low pressure and high pressure steam
90% of heat loss from a hot uninsulated pipe can be prevented by proper insulation

3. Steam cost Excel calculator

How to calculate the cost of steam generated in an industrial boiler ?

You can access to an Excel calculation tool in order to get a rough estimate of the steam cost from an industrial boiler : Steam Cost Excel calculation tool (click here)

Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.

Sources

[Hall] Rules of Thumb for Chemical Engineers, Hall, Elsevier, page 346

Steam cost calculation

What is the cost of steam generation in a factory ?

1. Steam cost : calculation method

Industrial Steam Cost Calculator

Calculation Results:

1.1 Step 1 : calculate the cost of fuel

1.2 Step 2 : calculate the cost of steam

Practical Plant Engineering Rules of Thumb & Safety Limits for Steam Generation:

2. Steam generation tips

3. Steam cost Excel calculator

How to calculate the cost of steam generated in an industrial boiler ?