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Calculation of Steam Consumption and Vaporization Capacity using OPEN PAN EVAPORATOR

Open Pan Evaporator:


AIM: Evaluation of Heat transfer coefficient and vaporization efficiency in an open pan evaporator

OBJECTIVES: To calculate the vaporization efficiency of an open pan evaporator and to calculate the heat transfer coefficient.
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PRINCIPLE / THEORY:


Evaporation is a unit operation wherein the solution is concentrated by the removal of solvent, namely water. It differs from drying in that the end product is a solid rather than a liquid. It differs from distillation in that the end product is a concentrated solution rather than a vapor. When a liquid surface is open to the atmosphere, a concentration gradient is set in between the liquid surface and atmospheric air. At the liquid surface, the partial pressure of vapor will be equal to the vapor pressure of the liquid at the surface temperature; the partial pressure of the vapor away from the liquid surface is determined by water vapor present in the atmosphere. The performance of any evaporator is governed by two factors,

Capacity and Economy
1. Capacity is defined as the amount of water evaporated /hr.
2. The economy is the amount of water evaporated /kg of steam. 
Steam consumption is defined as Capacity / Economy.


Vaporization efficiency is defined as:

Heat supplied per evaporating a fixed amount of water /Theoretical amount of heat required.

EQUIPMENT USED:
Steam-heated boiler, Water Cylinder, pan, and temperature indicators.


MATERIALS USED: Water / Milk can any liquid for study

EXPERIMENTAL PROCEDURE:
OPEN PAN EVAPORATOR experimental set up
OPEN PAN EVAPORATOR
1. The diameter of the vessel is measured.
2. The steam boiler is started and pressure is developed.
3. 0. 5 liters of milk is measured and poured into the pan.
4. Steam is allowed by opening the valve and steam pressure is adjusted to (0.5 to 1. kg/cm2) and stop clock is started.
5. The evaporation is continued until 80% of the liquid is evaporated and milk gets concentrated.
6. The boiling temperature of the milk is noted down.
7. Steam supply is started and the boiler is switched off.
8. The concentrated milk is collected and weighed.

OBSERVATIONS:

Diameter of pan = …… cm
Height from center =……..cm
The initial weight of milk = W1 Kg
The final weight of milk = W2 kg
Pressure gauge reading = , 
Surface temperature, TS = 0C 
Initial temperature of milk = Tm1 0C
Final temperature of milk = Tm2 0C
Time of evaporation = t, min
Mass of steam condensate collected, m = kg

DATA ANALYSIS:

Amount of water evaporated V = W1-W2
Rate of evaporation V1 = V/t Kg/min
The rate of heat transfer = V1*l J/min, where l = Latent heat of vaporization at atm pressure
Steam rate = m/t 
Vaporization efficiency = (V1/m) *100
Diameter of pan = d = cm
Height from center = h = cm
Heat transfer area = p * (1.2d)2/4 m2
Average milk boiling temperature = (Tm1+Tm2)/2 =Tm
Q = UADT 
U = Q/(A* Ts-Tm) W/m2Deg.C

The procedure is a sample calculation method used with a prototype pan evaporator. Dimensions will vary with the model of the equipment used in the experiment in determining the steam economy and efficiency of the steam evaporator. Studies on the efficiency of the evaporator for particular feed material will differ from the properties. To find out the data of that specific feed material number of consistent trail runs are done on open pan evaporator. 

Related topic: Double pipe heat exchanger study

Open Pan Evaporator Calculator

This calculator estimates the performance of an open pan evaporator. It is intended for educational purposes and preliminary analysis. Real-world evaporator performance can be affected by numerous factors not included here.

Diameter of the pan used for evaporation.



Height of the pan from the center.



Initial weight of the liquid to be evaporated (e.g., milk).



Final weight of the liquid after evaporation.



Pressure of the steam supplied.



Temperature of the heating surface.



Initial temperature of the liquid.



Final temperature of the liquid.



Time taken for evaporation process.



Mass of steam condensed during the evaporation process.



Specific heat capacity of the liquid being evaporated (e.g. for milk ~3900 J/kg°C).



Latent heat of vaporization of water at atmospheric pressure (default: 2257000 J/kg)



The ambient temperature of the surroundings. This is important for estimating heat losses.



Emissivity of the pan surface (typically between 0.05 and 1).



This Open Pan Evaporator Calculator provides a simplified way to estimate the performance of an open pan evaporation process. It allows you to input key parameters like pan dimensions, initial and final liquid weights and temperatures, steam pressure, and process duration to calculate important metrics such as evaporation rate, heat transfer rates, steam consumption, vaporization efficiency, and heat losses. To use the calculator, simply enter the relevant values into the input fields and click "Calculate". The results section will then display the calculated parameters, offering insights into the evaporator's energy efficiency and overall performance. However, it's crucial to remember that this calculator is a simplified tool for educational purposes only. Actual evaporator performance can be significantly affected by factors not included here, such as variations in liquid properties, atmospheric conditions, and heat transfer surface conditions. Therefore, the results should be considered as estimations and not used for critical design decisions without further, more detailed analysis. A full evaporator design requires sophisticated expertise and software.

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