Steam%Cane and Individual Body Heating Surface Calculation in Sugar Industry

Formulas to find Steam%Cane and Individual Body Heating Surface of Quintuple Effect Evaporator with online calculator

1. Calculation of steam%cane and evaporator set individual bodies heating surface have placed one of the major calculations in equipment design drawing of sugar process industry.

2. In the steam%cane calculation involve so many factors like type of multiple effect evaporators, types of juice heaters, types of pans,  bleeding arrangement for juice heating and massecuite boiling  ect.

3. Concentration of sugarcane juice in the sugar industry is done in multiple effect evaporators either in Quadruple, Quintuple, or DEVC + Quad. These evaporator systems are based on the Reileaux principle selected on the basis.

4. In maximum sugar industries Quintuple effect evaporator has been installed keeping in mind to get lower steam consumption in boiling house using extensive vapour bleeding.

5. This article provided formulas for steam%cane  calculation  and also gave formulas to find required heating surface of the individual  evaporator bodies. And also provided one powerful online calculator for above calculations.

Formulas involved in this calculation:

1. Pressure Drop Calculation:

The first step in this calculation find the pressure drop across the evaporator set and also find individual bodies pressures, temperatures, and Latent heat for given exhaust pressure and lost body vacuum of the evaporator set. It has been explained in my other article please go through the link below.

Principles and Pressure Drop Calculation across the Multiple Effect Evaporator Bodies

2. Vapour required for juice heating

Vapour required for juice heating = [ Q x Cp x ΔT ] / λ

• • Q=Quantity of juice flow in Ton/hr
  • Cp =Specific heat of juice Kcal/kg/^oC
  • ΔT =Temp difference of inlet and outlet of the juice
  • λ =Latent Heat  of the vapour in kal/kg 

(Note: If the DCH( direct contact heater) is used for juice heating then vapour required quantity for juice heating to be added to the quantity of juice for further calculation. Latent heat value to be taken as per heating vapour.)

3. Vapour required for massecuite boiling

Vapour required for massecuite boiling = K x M x [ (Brix of massecuite – Brix of feed material) / Brix of massecuite]

• • K = 1.5 for Batch Pan and 1.2 for Continuous Pan.
  • M = Quantity of massecuite in Ton/hr.

Note:

a) It is better to add moment water percentage to above-required vapour.

b) For better understanding and analysis propose to be calculate specific steam consumption of the individual massecuites like A,B & C m/c. The units of specific steam consumption is a Ton of vapour per Ton of massecuite.  ( i.e Specific steam consumption = Vapour required for massecuite boiling per ton of mssecuite)

4. Vapour consumption for miscellaneous

This includes pan washing, seed melting, molasses reconditioning, sulphur melting, and super heated wash water system, etc..

Generally, these were considered as on percentage of the crushing rate. Generally consider the values as follows as

• • a) For Pan washing take 0.2 to 0.25 % cane
  • b) For Seed melting take 0.4 to 0.6 % cane.
  • c) For molasses reconditioning take 0.4 to 0.6 % cane
  • d) For Super heated wash water (SHWW) system take 0.2 to 0.25% cane
  • e) For Sulphur melting purposes take 0.2 to 0.4 % cane. Now a days for sulphur melting follows like E- boiler or wapcon systems etc. to avoid 7ata steam.

5. Total Evaporation Rate

Total Evaporation rate = [ (Brix of Syrup) – (Brix of C.Jc) / (Brix of syrup) ] x Final clear juice quantity.

a) Here Brix of clear juice = Brix of mixed juice x [ (Mixed juice Quantity  / Final clear juice quantity) ]

b) C.Jc % Cane = Final quantity of clear juice x 100 / Crushing rate

c) Final clear juice quantity = Juice quaintly after the juice heating – Mud quantity in mixed juice ( Final clear juice quantity will change in the case of heating the juice in DCH otherwise it will be the same as the quantity of mixed juice).

Vapour Production = Evaporation Rate x Clear Juice Quantity in Ton/hr then calculate “ X “ Value ( X =Quantity of Vapour goes to the condenser  of the evaporator in Ton/hr)

( Note: ” X ” should have a positive value.

• • X =  Positive valve than given bleeding arrangement is ok
  • X =  Negative value than given bleeding arrangement should not possible so to change the bleeding arrangement (i.e Require vapour is more than vapour produced from Evaporators)

6. Steam requirement calculation

• Total Exhaust required for Process in Ton/hr = X +  Vapour required for Juice heating + Vapour required for massecuite boiling +  Vapour required for miscellaneous

Steam% Cane = Total Exhaust required for Process x 100 / Crushing Rate in TCH

For better understanding and analysis purposes we can calculate individual steam consumption as follows

1. 1. Steam%cane for total Juice Heating = Total Vapour required for juice heating x 100 / Crushing Rate in TCH.
   2. Steam%Cane for massecuite Boiling = Total Vapour required for massecuite boiling x 100 / Crushing Rate in TCH.
   3. Steam % Cane for Evaporators = Total Quantity of Vapour that goes to the evaporator condenser in Ton/hr x 100 / Crushing Rate in TCH.
   4. Steam%Cane for Miscellaneous= Total Vapour required for Miscellaneous x 100 / Crushing Rate in TCH

• Total Steam%cane = Steam%cane for total Juice Heating + Steam%Cane for massecuite Boiling   + Steam % Cane for Evaporators + Steam % Cane for Miscellaneous.

It is also helpful for cross-checking calculations.

7. Heating surface requirement for individual bodies

a) As per the general method.

Heating surface requirement = vapour production from the body in kg/hr / Evaporation rate of the body.

Evaporation rates can be calculated by the existing bleeding vapour arrangement.

Evaporation Rate = Vapour production in that body in Ton/hr x 100/ Total vapour production in all sets of evaporator bodies.

But in the calculation of the heating surface will be taking the general evaporation rates of evaporator bodies.

b) As per the E.Hugot formula

b) As Per Hugot given the Evaporation Rate of The Several Vessels of a multiple effects working under the condition of temperature drop from 120^oC to 55^oC

Heating surface requirement for evaporator bodies as per E.Hugot formula.

Heating surface requirement = Vapour production/ ΔT * Coefficient of heat transfer.

Outlet Brix of the body = [ (Juice Inlet Quantity  x Brix of inlet juice) / ( Juice inlet Quantity – Vapour Production in that particular body) ]

Average Brix of the body = [ Outlet Brix + Inlet Brix ] / 2

Boiling Point elevation =  Boiling point elevation found from HANDBOOK OF CANE SUGAR ENGINEERING by E.Hugot Page No. 501 table no.  32.3

(Note: This table considered the parameter liquid column height in the body, Brix of the body, and temperature of the liquid in that body.

a) For liquid column height generally take 1/3^rd height of the tube in Robert type body and 20% height of the tube in semi kestner body.

b) For the Brix of the body to take average brix.)

The effective boiling point of the body = Temperature of the body +  Boiling Point elevation.

ΔT = Temperature of inlet vapour of the body – Effective boiling point of the body

The coefficient of heat transfer is calculated from the Dessin formula as follows.

Dessin proposed a formula permitting the evaporation coefficient to be calculated for any vessel of a multiple effect:

C  = 0.001 (100 – B) (T – 54)

• • C = specific evaporation coefficient for the evaporator, in kg of vapour/ m²/^oC/hr
  • B = Brix of the juice leaving the vessel
  • T = temperature of the heating steam in the calendria, in °C (°F).

(Note: To get better results from the above formula, take in the place of coefficient 0.001 as follows as

• • For 1^st effect = 0.001,
  • 2^nd effect = 0.0009,
  • 3^rd effect= 0.0009,
  • 4^th effect = 0.0008,
  • 5^th effect = 0.0008.

Online calculator for Steam%Cane and Individual Body Heating Surface in  Quintuple Effect Evaporator.

Click Here

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