Quality of Feed based on Enthalpy of Feed and Latent Heat of Vaporization Calculator

Feed Quality Formula:

\[ q = \frac{\lambda + H_{fs} - H_f}{\lambda} \]

Molar Latent Heat of Vapor (λ):

J/mol

Molar Enthalpy of Feed at Boiling Point (H_fs):

J/mol

Molar Enthalpy of Feed (H_f):

J/mol

Feed Quality (q):

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1. What is Feed Quality in Distillation?

Definition: Feed Quality (q) represents the fraction of feed that is liquid in a distillation column. It's a crucial parameter in distillation column design and operation.

Purpose: This calculator helps chemical engineers determine the thermal condition of the feed entering a distillation column, which affects the number of theoretical stages required.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ q = \frac{\lambda + H_{fs} - H_f}{\lambda} \]

Where:

\( q \) — Feed quality (dimensionless)
\( \lambda \) — Molar latent heat of vaporization (J/mol)
\( H_{fs} \) — Molar enthalpy of feed at boiling point (J/mol)
\( H_f \) — Molar enthalpy of feed at current temperature (J/mol)

Explanation: The formula calculates the fraction of feed that is liquid by comparing the energy required to bring the feed to its boiling point with the latent heat of vaporization.

3. Interpretation of Feed Quality Values

Details:

q = 1: Feed is saturated liquid
q = 0: Feed is saturated vapor
0 < q < 1: Feed is vapor-liquid mixture
q > 1: Subcooled liquid feed
q < 0: Superheated vapor feed

4. Using the Calculator

Tips: Enter the molar latent heat of vaporization, molar enthalpy of feed at boiling point, and molar enthalpy of feed at current temperature. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a feed quality of 0.5 mean?
A: A q value of 0.5 indicates that the feed is 50% liquid and 50% vapor when entering the distillation column.

Q2: How does feed quality affect distillation?
A: Feed quality impacts the location of the feed stage and the energy requirements in both the rectifying and stripping sections.

Q3: Where can I find enthalpy data for my feed?
A: Use thermodynamic property tables, process simulation software, or experimental data for accurate enthalpy values.

Q4: What units should I use?
A: All enthalpy values must be in consistent units (J/mol in this calculator).

Q5: Can I use this for multi-component systems?
A: This formula works for multi-component systems, but you'll need to use appropriate average properties.