Why is steam measured in terms of mass?
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1. Ordinary gases (such as oxygen) are traded and settled based on volume; the volumetric flow rate measured under actual operating conditions is adjusted by accounting for temperature and pressure effects to standard conditions (20°C and 1 atmosphere) to facilitate uniform settlement in trade transactions； Steam is generally settled based on mass, and temperature and pressure adjustments are also required to convert it into mass for trade purposes. But to what standard condition are these temperature and pressure adjustments applied? 2. Why does everyone talk about steam in terms of tons – for example, saying that 200,000 tons of steam were produced this year – but not mention the corresponding pressure and temperature? Both produce 200,000 tons of steam per year, but one operates at 5 MPa and 150°C, while the other operates at 20 MPa and 200°C! The calories contained in them must be different, right! Isn’t it a problem to settle with quality?
Steam makes use primarily of its latent heat. It is true that the heat content of steam varies at different pressures and temperatures, but since steam has a low specific heat, heating is achieved by utilizing its latent heat; therefore, the amount of steam is generally calculated based on its mass rather than its volume； As for what level of steam mass compensation you are referring to, it actually depends mainly on the temperature in order to determine the density of the steam; thereafter, the mass flow rate of the steam is calculated based on the volume flow rate
The volume under standard conditions is equivalent to mass, and the conversion factor is a constant value as well. . . A single hair on the ball ..........
Count them as standard cubic feet, with temperature and pressure compensation
I support the answer from the second floor: steam relies on heat, and heat capacity does not take volume into account; it is only in the calculation of mass that volume is multiplied by density using the instrument
If you think more about how steam is produced, it will be easier to understand! Additionally, steam comes in two forms: saturated steam and superheated steam, which is different from ideal gases.
Energy accounting is based on mass!
At different pressures, the density (or specific volume) of steam varies; steam utilizes its latent heat of vaporization, and it is more convenient to perform calculations using mass
This post was last edited by Zhuge Sima Linghu Chong on 2019-7-22 at 12:45. The main question raised by the poster is as follows: For steam of the same mass, at 5 MPa and 150°C versus 20 MPa and 200°C, its price should be different (due to differences in calorific value); however, since their masses are the same, if pricing is based on mass, then their prices should be identical. Isn’t it a bit unreasonable? I haven’t delved deeply into topics related to this, so I have the same question.
The heating companies set different prices for steam; they determine the price based on quality, so how could there be the same price?
I see. So, in other words, steam with different pressures and temperatures but the same mass will have different prices – is that how I should understand it? Thank you!