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Increase production rate and solve bottle necks at
Carbonatation and Phosphatation-Clarification types of sugar
Refineries with the use of High performance Adsorbents
E.M.Sarir(1),C.A.Donado(2), A.Ogheneovo(3),R.Villanueva(4),
H. Tobar(5),A.Boghari(6), N.Espaneuva(7)
(1)
CarboUA International, (2)CarboUA do Brazil, (3)CarboUA Nigeria, (4)Abdul Monem Sugar,
(5)
United Sugar Company, (6)Incauca Refinery, (7)Ex-Dangote Sugar Refinery
Abstract:
This paper reviews the use of patent pending high performance adsorbents
used in some sugar Refineries to achieve enhanced daily production, process
efficiency, improved filterability and energy saving for carbonatation and
phosphotation refineries. Different processes and technologies for sugar
purification and their impact on sugar recovery are reviewed and discussed. How
the patent pending adsorbent enhanced carbonatation and phosphatation
clarification, as well as its further application with double stage purification
methods to by-pass unit operations such as granular activated carbon or ionexchange resin was reported. The benefits are presented based on: improved final
liquor colors and better refined quality, improved daily throughput of sugar
solids, improved conversion rates of refined sugar per ton of raw sugar melt,
reduction in the amount of recycled (double-processed) recovery sugar and
reduction in energy consumption per ton of sugar produced.
Key words: clarification, efficiency, energy use, production, quality of
sugar, sugar refining.
Introduction:
This paper presents a review and comparison between different types of
clarification and decolorization processes, including the newly developed patent
pending high-performance adsorbents, which have demonstrated to be an
excellent alternative in terms of cost-benefit. Additional to the process
comparison, some case studies amongst others regarding how specific problems
have been solved are also presented.
Production of better quality refined sugar, maximizing process efficiency
and minimizing energy consumption, are the basic objectives of all sugar
Refineries in order to be able to optimize profit margin and returns to
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International Conference on:
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stakeholders. Current processes for clarification and decolourization offer the
opportunity to process raw sugar so that the final liquor after all purification
process has the necessary conditions for a good exhaustion (recovery of sucrose
in crystals) and fulfilling the quality parameters required in the industry.
Choosing the right kind of clarification process and / or decolorization
requires a careful evaluation of the pros and cons of each alternative technology
available in the market and deciding which one(s) best meets the needs of each
particular process. Selection of the correct purification process and strategy is
very important, not only because it will obviously determine the final quality of
the processed sugar but will also be a critical factor to determine the refinery
yield
Several authors have made fair comparisons between the different
purification process technologies, especially in terms of efficiency of purification,
color removal, etc. but only a few studies have so far been carried out to analyze
the cost-benefit of each operation technology, considering purification efficiency,
operation cost and effect on the refinery yield. We try to shed some light on this
in this paper.
Comparison of Various Color Removal Technologies
Firstly, the comparison of these color removal technologies and process
will be done using a modified table that was first presented by Rein (2006). With
the advent of the new patent pending high performance adsorbents, the authors
were compelled to make minor changes to the table and also include a new
column, with the heading: high performance adsorbents to enable a comparison
to be made between all available technologies as in table (I) below.
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Table (I): Effect of Decolourization Processes on Colour Types
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From table (I) above, it is clear that there are different types of purification
processes; the high performance adsorbents are more adaptable to meet a wider
variety of needs, with a better cost-process ratio and better flexibility to different
process conditions.
Now, the reason why high performance adsorbents are successfully
adapted to solve different problems and bottle necks in sugar refinery is because
they combine the main principles and active ingredients of the other clarification
and decolorization process in one integrated solution.
To observe in more details this distinct characteristic of the high
performance adsorbent, an adaptation of the table presented by Davis (2001) in
its technical paper of 2001 “The Chemistry of Color Removal Processing
Perspective” is presented in table (II) below:
Table (II): Effect of Decolorization Processes on Color Types.
COLOR PROCESS
Phenolics Flavonoids Melanoidins Caramels
ADF
Color
Products Precursors
Carbonatation
Okay
X
Okay
Sulphitation
Okay
Okay
Okay
X
X
Okay
Okay
Okay
Okay
OKay
Okay
Phosphatation
Color Precipitant
OxidativeDecolourants
Okay
Okay
OKay
OKay
X
X
Okay
X
Okay
ActivatedCarbon
OKay
OKay
Okay
OKay
X
High PerformanceAdsorbents
OKay
OKay
Okay
OKay
Okay
Ion Exchange
Okay
OKay
Combining the main strengths of the existing clarification and
decolorization process it is possible to create a “single process/product” with
ability to remove more impurities and generate proper conditions for an enhanced
plant yield.
PRACTICAL PROBLEM SOLVING APPROACH
Case Study No.1
PROCESS BOTTLENECK
A 900 t/d sugar refinery in Colombia operates a back end Refinery to a
cane sugar mill. As a phosphatation refinery, it processes melt liquor with a color
of 400 - 500 IU. Before the project at this mill the fine liquor had a color of 200 250 IU after the phosphatation clarifier. The plant operated a back-boiling
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International Conference on:
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crystallization scheme with liquor to syrup ratio of 60 : 40.
PROPOSED SOLUTION USING HIGH PERFORMANCE ADSORBENT
The aim of the project was to increase the production rate of the plant by
improving on the color and turbidity removal in the phosphatation clarifier,
thereby increasing sugar quality in order to meet the specifications of customers
with stricter standards (such as bottlers).
HOW THE PROBLEM WAS SOLVED
250 mg/kg of a high performance adsorbent was added to the raw sugar
being melted. This lowered the syrup color after the pressure filter to a range of
100 - 150IU. As a result the ratio of liquor to syrup for the back boiling
crystallization system was modified to 50: 50. The reduced color in the syrup
allowed better massecuite exhaustion and reduced run-off recirculation within the
white house. This increased the throughput tremendously, produced sugar of
better quality and saved considerable quantity of energy.
DISCUSSION OF RESULTS
Table (III) shows the results of adding the adsorbent. The color removal
was improved by 21% enabling the production of better quality sugar.
Table (III) Color removal comparism
Color Profile – Color Removal Comparison.
Table (IV) Phosphotation chemical reduction
Chemical Reduction
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International Conference on:
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From table (IV), it can be seen that addition of 200mg/kg high
performance adsorbent reduced the quantity of phosphoric acid by 15%,
flocculant by 30%, polymer decolorant by 53% and filtration aid by 25%. It also
led to a 100% elimination of granulated activated carbon. This is evident that the
patent pending high performance adsorbent combines the properties of
clarification chemicals and other color removing unit operations.
The improvement in the final liquor quality led to a reduction in the
amount of wash syrup in the centrifugals, which resulted in generating less runoff syrup (energy saving) by increasing the liquor to runoff syrup ratio to 50:50 .
It was possible to reduce the amount of syrups in the white sugar house by 42%
(increased yield and quality).
Fig 1
Fig 1: shows the number of 50:50 strikes after addition of the adsorbent.
The daily refined sugar production increased by 6% after the application of
the adsorbent as shown in figure 1.
Case Study No.2
PROCESS BOTTLENECK
This involves a carbonatation sugar refinery in the Middle East with a
production capacity of 3000 t/d. It processes raw sugar of 900 – 1300 IU. The
carbonatation is followed by a filtration step and granular activated carbon for
colour removal.
The existing process parameters:
-
Flow rate of 235 m3/hr of Clarified Liquor
Syrup Brix 55% to 58%
Syrup color after filtration of 750 IU
Refined sugar output of 3300 t /d
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International Conference on:
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PROPOSED SOLUTION
The aim of the project was to increase the sugar throughput by increasing
the Brix of the syrups and/or the process flow rate. By improving the
carbonatation performance a lower final liquor color should be obtained, thereby
giving a higher rate of white sugar production with constant or higher sugar
quality. Here the high performance adsorbent was added to the maturation tank
after carbonatation located before filtration.
PROBLEM SOLVED
The process parameters of the enhanced carbonatation using the patent
pending high quality adsorbent system is as follows:
-
Flow rate of 260 m3/h (+9.6%) syrup
61% Brix of the syrup
Color of the syrup after filtration of 525 IU
Refined sugar output of 3700 t /d.
The improved adsorption of non-sugars like starch and dextran allowed for
a better filtration rate from the Laboratory analysis of the syrup.
Table (V): Reduction in fine liquor color
Fine Liquor
Daily INCREASE
Colour (After GAC)
Refined Sugar Output
Carbonatation Only
225 - 250 IU
---
EnhancedCarbonation
125 - 150 IU
12% increase
ProcessMethod
Table (V) shows the reduction of color in the fine liquor after the granular
activated carbon (GAC) due to addition of the high quality adsorbent.
The factory was able to reduce the centrifugal wash time to 2 and 1seconds
on the 1st strike, compared to 3 and 2 seconds with the normal carbonatation
process, thereby saving some quantity of wash water and energy.
Maximizing daily production capacity within the constraints of existing
sugar house capacity allowed a 12% increase in the daily production of refined
sugar as in table vi below:
Table (VI) Process Comparism :Carbonatation only vs Enhanced Carbonatation
ProcessMethod
ProcessFlow
Rate
(m3/hr)
Liquor Concentration FilteredLiquor Average RSO
ºBrix
Colour (IU)
(Tons/day)
Carbonatation Only
235
~ 55
775
3300
Enhanced Carbonatation
260
~ 61
525
3700
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International Conference on:
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A 19% reduction in fuel oil consumption, a 25% reduction in steam
consumption, and a 29% reduction in water consumption were achieved as in
table vii
Table (VII) Process Comparism: Energy saving
FuelOil
Steam
Water
(kg/ton RSO)
(Tons/Ton
RSO)
(kg/ton RSO)
Carbonatation Only
84
1.13
620
Enhanced Carbonatation
68
0.84
440
ProcessMethod
Case study No.3
PROCESS BOTTLENECK
This refers to a stand alone phosphatation refinery in Africa, which
produces, as stand-alone refinery, more than 3000 t/day.
It processes raw sugar with 600 – 700 IU. At this refinery the syrup is
decolorized by an ion exchange, after phosphatation stage, resulting in a final
liquor color of 220 to 280 IU. The refinery uses a straight crystallization scheme,
whereby the first three sugars R1, R2and R3 were blended and packed. Before
the project, the R4 sugar color was too high to be blended into the product for
sale. Therefore the R3 stage back-boiling system was used.
PROPOSED SOLUTION
The aim of the project was to eliminate the need for back-boiling at the R3
stage and to produce a lower color R4 sugar, so that it could be blended with R1,
R2 and R3 without compromising on quality.
PROBLEM SOLVED
The addition of the adsorbent easily reduced the color of theR4 sugar,
making it suitable for sale, and increased the daily production rate by 2.1% on the
average. Table 8 shows the color of the white sugar produced at different stages
in the white sugar house. The typical blended color of the white sugar for sale
decreased from 60 – 80 IU to 30 – 45 IU after the addition of the adsorbent.
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Table (VIII) Refined Sugar color profile
ProcessMethod
Fine LiquorColour
(IU)
Phosphatation Then
IER
220-280 IU
Phosphatation
WITH
Adsorbent,followed
by IER
120-180 IU
R1 – R4 Sugar
Colours (IU)
R1: 25
R2: 50
R3: 100
R4: N/A
R1: 12
R2: 25
R3: 38
R4: 75
Considerable steam savings was achieved as a result of removing the need
for back-boiling. At the same time use of phosphoric acid and decolourants was
reduced as shown in table (IX).
Table (IX) Phosphatation chemical reduction
ProcessMethod
Phosphatation Only
Phosphatation WITH
Adsorbent
PolymerDecolourant
(ppm)
300ppm
PhosphoricAcid
(ppm)
450ppm
125ppm
250ppm
Enhanced phosphatation generated optimization of the chemicals in
Clarification process at the same time ,th 4th strike was achieved throughout and
a plant production increase of + 2.1%, resulting in steam savings and avoiding
the 3rd strike back boiling.
Case Study No.4
PROCESS BOTTLENECK
This involves a Carbonatation Sugar Refinery in South Asia with a
production capacity of about 800 Tons/day and normally processes VHP raw
sugar. The Carbonatation process is followed by two-Stage Rotary Filtration and
Ion-Exchange Resin Columns.
In this particular study, the objective was to process a High Color Raw
Sugar from Southeast Asia (about 12,000 IU color), which was mixed with the
VHP raw sugar at the rate of about 5% only, before the applications of the High
Performance Adsorbent.
The existing parameters were before the application of the high
performance adsorbent; 5% mix of High Color Raw Sugar with VHP Raw sugar:
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1. Flow rate of maximum of 45m3 per Hour
2. Brix of Filtered Liquor at 58 to 60
3. Average Color Removal in Carbonatation Process of about 50%, with Raw
Melt Liquor at 1650 IU and Filtered Liquor at 825 IU.
4. Refined Sugar Output on average of about 688 tons/day
PROPOSED SOLUTION
The objective was to maximize the mixing rate of the high color raw sugar
from Southeast Asia with VHP raw sugar, by the addition of high performance
adsorbent in the carbonated liquor/filter supply tank, thereby improving the
filterability of the process liquor and the color removal with the enhanced
carbonatation process. Consequently, the mixing ratio of the high color sugar
with the VHP raw sugar could be increased thus increasing the refined sugar
output.
PROBLEM SOLVED
With the application of the High Performance Adsorbent, the following
improvements were achieved in the Sugar Refinery Process:
1. Flow rate was maintained at 50m3 per hour (about 11% increase)
2. Filtration Cycle was improved from average of 5-6 hours to up to 7 hours
(improvements by 15-20%).
The Color Removal by the Enhanced Carbonatation Process was improved to
about 72%, with Raw Melt Liquor Average Color exceeding 2300 IU but with
Filtered Liquor at Average Color of only 670IU.
3. Refined Sugar Output increased to 785 tons/day.
Table(x) below shows the Performance of the Sugar Refinery Process with
applications of High Performance Adsorbent Product as compared to the existing
process:
Table(X): Process comparison. Carbonatation Only vs. Enhanced carbonatation
High Color
Sugar/VHP
ProcessMethod Mix Ratio
(%)
Carbonatation
5
Only
Enhanced
20-30
Carbonatation
Process
Flow
Rate
(m3/hr)
(Hours)
Filtered
Liquor
Color
(IU)
45
5-6
830
50
--
688
--
50
Up to 7
670
72
22%
785
14%
Filter
Cycle
Color Removal
Refined Sugar
Melted vs
Output
Filtered
(%) Increase Ton/day Increase
The applications of the High Performance Adsorbent Products resulted in
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optimizing the mixing rate of High Color Sugar with VHP Raw Sugar, and
further increasing the Refined Sugar Output. Consequently, the available amount
of 15,000 tons High Color Raw Sugar from Southeast Asia could be fully
consumed in the sugar refinery process in about 4 months with 20-30% mixing
rate, as compared to more than 1 year with only 5% mixing.
SPECIAL SECTION
It is good news to note that CarboUA has launched a new range of high
performance adsorbents which are not carbon based and are more potent, whitish
in appearance and gives better performance. This new array of products: FRS-CJ
and FRS-EW have been tried in so many Refineries in Africa, South America and
Asia with excellent results.
Also in the Mills, we have got some new line of products: FRS-J for the
juice treatment and the CarboUA S type1-5 with unique properties for use in the
Pans to remove impurities.
GENERAL CONCLUSIONS
The use of high performance process aids have been shown to significantly
enhance Carbonatation clarification operations in the refinery via improvements
in process throughput related to flow rate and brix increases and improved color
removal in the Carbonatation stage.
These benefits can enable an increase in daily refined sugar output (RSO)
even with the constraints of existing process equipment, as well as reduction in
energy consumption per ton RSO.
The use of high performance process aids have also been shown to enhance
the Phosphatation clarification operations in the refinery via improvements in
color/impurity removal; this can result in lower fine liquor color and
improvements in daily sugar produced via improved daily conversion of feed
sugar to the desired crystal product sugar in a single pass (obtaining R4 as white
sugar for example, instead of reprocessing it as crop sugar).
Further, the process aids can be utilized in a secondary clarification step
(either afterphosphatation or after carbonatation) to impart additional
DECOLOURIZATION and improved sugar throughput (flow rate and brix
increases) at dosages much lower than conventional powder carbon.
In all the cases mentioned above it is good to note that the cost benefit
analysis resulted in a significant economic advantages to the refineries and this
translates into millions of dollars when evaluated over a short operation period as
the case may be.
Due to recent shortages of world sugar supply compared to demand, as
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well as projections of continued growing demand, the ability to improve
production capacity and efficiencies within existing refineries is a worthwhile
and timely pursuit.
References
REIN P. “Cane Sugar Engineering”. 2006. Comparison of Decolorization
Systems. pp. 549.
DAVIS S.B. “The Chemistry of Color Removal:
Perspective”.2001. Comparison of Processes. pp. 334
A
Processing
PABON B. “International Sugar Journal”. Improving the efficiency of
carbon/diatomaceous earth filtration in sugar refining using the high
quality adsorbent”. 2003. Entire Document
BUENO D.J. “International Sugar Journal”. Enhanced Phosphatation
Clarification Performance for Improved Production Efficiency in Sugar
Refineries and Sugar Mills with High Performance Process Aids,
2011.Efficiency and Product Quality in Sugar Refineries. 2010. Improving
Total Clarification by Utilizing A Secondary Clarification Step.
SARIR E. “International Sugar Journal”. Improving Daily Production Capacity
and Energy
BERNABE G. “Phil-Sutech”. Enhanced Carbonatation and Phosphatation
Clarification performance for improved production efficiency and product
quality in the Sugar Refinery, 2011
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