Design Calculation of Juice Defecator and Sulphitor with online calculator
In this article explained about juice defecator and juice sulphitor calculations like diameter, overflow height, find the shock lime point etc.
Juice reaction vessels (Defecator or Sulphitor)
a) For better juice clarification and excellent mud settling rate, the juice defecation and sulphitation reaction vessels play a key role. This reaction vessel is the heart of the overall juice clarification station.
b) In Juice sulphitor reaction vessel having the connection of milk of lime and SO2 gas but in defector only having milk of lime connection. This is the major deference for both systems. The remaining design criteria for both reaction vessels are the same.
c) Juice liming only is done in the vessel called as juice defecator.
d) Juice liming and sulphitation are done in the vessel called as Juice sulphiter. Where the juice after passing the mass flow meter and heating to 70 to 75oC. Comes in contact with lime and sulphur dioxide gas. The juice entry from the top of the gas absorbance tower and then enters into the bottom of the juice sulphiter. After being contact with lime and SO2 gas from about 7 to 8 minutes it over flow into Subjected juice receiving tank. The quantities of lime and sulphur dioxide depend upon the pH of the juice.
The design of a sulphitation/defection unit of great importance and needs the consideration from all angles. The design of the unit should ensure the following requirements.
The juice sulphiter vessel is normally provided with stirrer, milk of lime inlet, SO2 gas sparger , SO2 gas absorption tower, milk of lime dosing tank , preliming tank(depend upon design), treated juice over flow box, test or sample cocks and liquidation valves etc.
Retention:
a) Retention or contact of juice with lime and gas must be given a sufficient time to complete precipitation.
b) It is generally take for both reaction vessels having 7 to 8 minutes.
Stirrer:
a) Stirrer speed should be low because of floc break avoiding. Gentle agitation is utmost importance to bring about maximum flocculation.
b) The RPM of the stirrer having 16 to 24. While providing the baffle arrangement in the vessel then rpm lies 16 to 18 and with out baffles the rpm goes upto 20 to 24.
c) In some reaction vessel designs not having the stirrer arrangement. In this type of design having two to three compartment. While juice passing through this compartments, it can be mixed proper and completed reaction.
Lime entry
a) Lime dosing is the one of the main design unit for the reaction vessel. As per the method of reaction the lime entry will be arranged.
b) For shock lime method lime entry point will be provide 8 to 10 secs before entry of the juice into the reaction vessel.
c) In simultaneous method lime entry to be provide just before or near to SO2 gas distribution system.
Juice over flow:
There should be a gutter on the periphery for the out let of juice. The gutter volume should be cover the total juice flow rate at the outlet point. (i.e The juice collection from the vessel to be cover equally overflow from the all sides).
Hydrostatic head :
This should be 2.0 to 2.4 meter. i.e juice column height(juice overflow height) in the reaction vessel . Normally here bottom cone height not consider.
SO2 distribution system: (For juice sulphitor)
a) Distribution of the SO2 gas in juice sulphitation tanks one of the major important criteria for getting better clarification.
b) The SO2 gas distribution system mainly two types of designs. Sparger type SO2 gas distribution system and Cross Type gas distribution system.
c) Generally Sparger type SO2 gas distribution system is preferable of smaller diameter type reaction vessels and Cross Type gas distribution system for larger diameter vessels.
d) Total cross section area of gas distribution holes should be 150 to 200 % of main SO2 gas line. Hole size shall be as small as possible. It should not be larger 25 to 30mm. When compare to larger diameter SO2 gas bubble, the smaller dia of the SO2 gas bubbles having higher surface area to contact the juice.
Gas Absorbance tower:
a) The function of this tower can be defined as to absorbed the residual SO2 left over in the gas after completing the reaction in the main vessel.
b) It reduces the consumption of sulphur and also to give the effect of partial presulphitation.
c) The SO2 gas is quickly absorbed in the juice while traveling in upward direction. In this design provide baffle arrangement for proper contact of juice and residual SO2 gas. The diameter and number of baffles to be provided on the basis about minimum 10secs of contact time.
Sampling Points:
Sampling point shall be provide for shock lime and final juice to continuously checking the pH.
Comparision of defecation and sulphitation process :
a) As the defecation process is only used for the manufacture of raw sugar and sulphitation process can be applied to produce planitation white sugar. (i. e The sulphitation is the single step of clarification system to get the good colour of the sugar)
b) Defacation process is the oldest method of the juice clarification . sulphitation process is the 3rd development of the juice clarification .
c) Defecation process is the cheapest than sulphitation process.
d) Sulphitation process results in a superior purification of the juice than defecation due to the removal of a greater quantity of non sugars, collides etc.
e) CaO content of clear juice in defecation process is in the range of 90ppm to 120ppm where as in sulphitation process,the range is 400ppm to 600ppm. The very low CaO content in defecation process results in drastic reduction of scaling at evaporators.
f) The lime consumption in defecation ( 0.1 – 0.12% on cane ) is less than the sulphitation process (0.15 to 0.20% on cane).
Design of the Juice reaction vessel ( Calculate with example).
Dia of the juice reaction vessel ( D ) (Defecator / Sulphitor )
Required Data:
Crushing capacity – 5000TCD = 5000/22 = 227 TCH (Calculate 22 hrs basis).
Juice % to inlet of reaction Vessel (Defecator or sulphitor) = 115%
Reaction Time = 7 minutes.
Juice column height in the reaction vessel ( H )(Generally bottom cone height not consider) = 2.2meters ( 2 to 2.4mtr )
Specific volume of the juice = 1.06 gm/ml3.
Calculation Part:
Volume of the juice in T/ hr = Crushing rate x Juice % = 227 x 115% = 261.05 T/hr.
Volume of the juice in M3/min. = Volume of the juice (T/hr) / ( 60 x Specific volume of the juice).
= 261.05 / (60 x 1.06) = 4.10456 M3/min.
Volume of juice for given retention time ( V ) =4.10456 x 7 = 28.73192 M3
Holding Volume of the reaction vessel ( V ) = (π/4) x D2 x H
D2 = 28.73192 /( 2.2 x 0.785) = 16.6369
D = 4.0788 mtr = 4100mm.
Find the Retention time of the existing Reaction vessel (Defecator / Sulphitor)
Required Data:
Crushing capacity – 5000TCD = 5000/24 = 208 TCH (Calculate 24 hrs basis).
Juice % to inlet of reaction Vessel (Defecator or sulphitor) = 115%
Dia of the reaction tank ( D )= 4.2 meters
Reaction Time ( T ) = ? minutes.
Juice column height in the reaction vessel ( H )(Generally bottom cone height not consider) = 2.1meters
Specific volume of the juice = 1.06 gm/ml3.
Calculation Part:
Juice reaction tank holding volume ( V ) = (π/4) x D2 x H = 0.785 x (4.2)2 x 2.1 = 29.0795 M3
Juice flow rate ( F ) = (208 x 115% ) / (3600 x 1.06 ) = 0.0626833 M3 /sec.
Retention Time = V / F = 29.0795/0.0626833 = 463.9 sec = 7.7 minutes.
Find the shock lime point for juice sulphitor
Required Data:
Crushing capacity – 5000TCD = 5000/24 = 208 TCH (Calculate 24 hrs basis).
Juice % to inlet of reaction Vessel (Defecator or sulphitor) = 115%
Dia of the juice inlet line (after the SO2 gas absorption tower) ( D )= 400mm
Shock lime reaction time ( T ) = 10 sec (8 to 10 sec)
The specific volume of the juice = 1.06 gm/ml3.
Shock lime point throughout the juice inlet ( H )= Distance between the Juice inlet of the vessel to shock lime point.
Calculation:
Calculate juice volume for giving 10 sec time M3 ( V )
Juice Volume ( V ) = (208 x 115% x 10) / (3600 x 1.06 ) = 0.626833 M3 / 10 sec.
V = (π/4) x D2 x H
H = V / [ (π/4) x D2 ]
H = 0.626833 / (0.785 x 0.4 x 0.4 ) = 4.991 meter.
i.e Shock lime point to be provided from the juice inlet point to 4991mm distance, throughout the juice inlet pipeline.
SO2 Gas distribution system opening area calculation
( sparger or cross-type SO2 gas system holes opening calculation)
Required Data
SO2 gas inlet line dia ( D ) = 200mm
Generally, the sparger opening area to take 150 to 200% of the gas inlet line cross-sectional area
Here Considered 200% and calculated for both distribution systems
For better SO2 gas distribution hole size of the sparger shall be not more than 40mm and for cross-type SO2 gas distribution system shall be not more than 30mm. At the same time smaller holes diameter, the higher the possibility of jamming may take place.
For Sparger Type : The hole size is better to take progressively increased as 20, 25, 30 & 38mm diameter otherwise it is to be take equal size. At the top of the sparger one hole of 40 to 45mm diameter may also be provide to ascertain complete SO2 gas removal.
Total holes opening area (A )= Gas inlet line cross sectional area x 200% = (π/4) x D2 = 0.785 x 0.2 x 0.2 x 200%= 0.0628 m2
Consider here 50% cross section area shall be provided of the below 25mm dia holes.
Choose the size of the holes and number of holes as per accommodate in the sparger area.
20mm size 50no.s, = 0.785 x 0.02 x 0.02 x 50 = 0.0157 m2
25mm size 45nos = 0.785 x 0.025 x 0.025 x 45 = 0.022078 m2
32 mm size 30 no.s = 0.785 x 0.032 x 0.032 x 50 = 0.024115 m2
40 mm size 1 no. = 0.785 x 0.04 x 0.04 x 1 = 0.001256 m2
Total holes opening area = 0.63149 m2
For cross-type SO2 gas distribution system : In this system, SO2 gas distribution holes diameter shall be not more than 30mm. For the inlet gas branch line to take less number of holes (Single row) and for the remaining branch line to take double row holes.
Total required number of holes (Each Hole size 20mm) = 0.0628 / (0.785 x 0.02 x 0.02) = 200 no.s
Online Calculator for Design of Juice Sulphitor / Juice Defecator
Note : In this calculator provided four sheets regarding
- a) Calculate reaction tank dia.
- b) Calculation of reaction time for existing juice reaction tank.
- c) Calculation of overflow juice height for existing reaction vessel
- d) Finding the shock lime point for juice sulphitor.
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