Question

The component that is fitted to increase the temperature and reuse the vapours from vapour separator in a multiple effect evaporator is

• A. DSI
• B. Flash vessel
• C. TVR
• D. Pre-heater

Hint:

Evaporator Energy Optimization:
TVR (Thermal Vapour Recompressor) = Recompresses and reuses boiling vapor using motive steam.
MVR (Mechanical Vapour Recompressor) = Uses mechanical turbo-compressors.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Thermal energy recycling in milk evaporation: a Thermal Vapour Recompressor (TVR steam ejector) entrains low-pressure boiling vapor from the separator, mixes it with high-pressure motive boiler steam in a convergent-divergent supersonic nozzle, and discharges the re-energized vapor at higher temperature and pressure into the calandria to double steam economy.
Key Formula or Approach:
\[ \text{High-Pressure Motive Steam } (P_1) + \text{Separator Vapor } (P_2) \xrightarrow{\mathbf{TVR \text{ (Thermo-Compressor)}}} \mathbf{Compressed \text{ } Heating \text{ } Vapor } (P_3 > P_2) \]

Step 2: Detailed Explanation:
In multiple effect milk evaporator engineering and thermal vapor recompression:
- Thermal Vapour Recompressor (TVR) (C) (Steam Jet Thermo-Compressor):
1. A high-efficiency static convergent-divergent nozzle assembly fitted to multiple effect falling film evaporators.
2. It utilizes high-pressure motive steam ($6 - 10\text{ bar}$) from the dairy boiler expanding at supersonic velocity through a de Laval nozzle to create a strong suction vacuum.
3. It draws a significant fraction ($30\% - 50\%$) of the low-temperature boiling water vapor leaving the vapor separator.
4. In the mixing chamber and diffuser section, the kinetic energy converts back to static pressure, increasing the temperature and pressure of the combined vapor, which is then discharged back into the first-effect calandria as heating medium.
5. A TVR increases evaporator steam economy equivalent to adding an entire extra effect (e.g., a 3-effect TVR achieves steam economy equal to a 4-effect plant).

Step 3: Final Answer:
Therefore, the component fitted is TVR, corresponding to option (C).