# Energy Content of Steam: Variation with Pressure

• rollingstein
In summary, the conversation revolves around a steam calculator provided by TLV, where the cost of steam in $/ton appears to be lower at high pressure compared to low pressure. The speaker is questioning the logic behind this, considering the higher energy content of high pressure steam. They mention ignoring factors such as boiler efficiency and losses, and provide their assumptions for coal cost and calorific value. They ask for any potential errors in their calculations. rollingstein Gold Member I was playing with an online steam calculator provided by TLV, one of the bigger steam equipment vendors & the steam cost it calculates ($/ton) seems lower at high P than low Pressure.

http://www.tlv.com/global/TI/calculator/steam-unit-cost.html

e.g. The $/ton of 200 bar steam seems 6.09 vs 7.17 for 10 bar steam. Does this make sense? I always intuitively thought there's a whole lot energy content in high pressure steam than low pressure. So why would the cost per ton of low pressure steam be higher? For now I'm ignoring the relative efficiencies of low and high pressure boilers, differential losses etc. I assumed saturated steam for both cases and feed water at 90 C which seem reasonable assumptions. Coal I assumed was$70/ton with a calorific value of 5600 kcal/kg. i.e. Energy unit cost of 0.0125 \$/Mcal

Do any of my assumptions seem unreasonable? Or a bug in my calculations?

Check your steam tables for the vapor enthalpy at the two pressures.

## 1. What is the energy content of steam?

The energy content of steam refers to the amount of thermal energy contained in steam, which is typically measured in British Thermal Units (BTUs) or joules. It represents the amount of heat that can be transferred from the steam to another substance.

## 2. How does the energy content of steam vary with pressure?

The energy content of steam increases as the pressure increases. This is because at higher pressures, the steam is able to contain more thermal energy, resulting in a higher energy content.

## 3. What is the relationship between energy content and pressure in steam?

The relationship between energy content and pressure in steam is directly proportional. This means that as the pressure increases, the energy content also increases, and vice versa.

## 4. How does the energy content of steam affect its ability to do work?

The energy content of steam is directly related to its ability to do work. The higher the energy content, the more heat energy is available to do work, such as powering machinery or generating electricity.

## 5. Can the energy content of steam be changed without changing the pressure?

Yes, the energy content of steam can be changed without changing the pressure by altering the temperature. As the temperature of steam increases, its energy content also increases, even if the pressure remains constant.

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