International Conference on:
“New Role for the World Sugar Economy in a Changed Political and
Economic Environment ”
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 ion-exchange 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 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.
Table (I): Effect of Decolourization Processes on Colour Types
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 Products / Color PrecursorsCarbonatation / Okay / X / Okay / Okay
Sulphitation / Okay / Okay / Okay / Okay
Phosphatation / X / X / Okay / Okay / Okay
Color Precipitant / Okay / OKay / Okay
OxidativeDecolourants / OKay / OKay / Okay
Ion Exchange / X / X / Okay / X / Okay
ActivatedCarbon / OKay / OKay / Okay / OKay / X
High PerformanceAdsorbents / OKay / OKay / Okay / OKay / 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 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
Table (IV) Phosphotation chemical reduction
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 run-off 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
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
ProcessMethod / Fine Liquor / Daily INCREASEColour (After GAC) / Refined Sugar Output
Carbonatation Only / 225 - 250 IU / ---
EnhancedCarbonation / 125 - 150 IU / 12% increase
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 / LiquorConcentration / FilteredLiquor / Average RSO(m3/hr) / ºBrix / Colour (IU) / (Tons/day)
CarbonatationOnly / 235 / ~ 55 / 775 / 3300
Enhanced Carbonatation / 260 / ~ 61 / 525 / 3700
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
ProcessMethod / FuelOil / Steam / Water(kg/ton RSO) / (Tons/Ton RSO) / (kg/ton RSO)
Carbonatation Only / 84 / 1.13 / 620
Enhanced Carbonatation / 68 / 0.84 / 440
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.
Table (VIII) Refined Sugar color profile
ProcessMethod / Fine LiquorColour (IU) / R1 – R4 Sugar Colours (IU)Phosphatation Then IER / 220-280 IU / R1: 25
R2: 50
R3: 100
R4: N/A
Phosphatation WITH Adsorbent,followed by IER / 120-180 IU / 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 / PolymerDecolourant (ppm) / PhosphoricAcid (ppm)Phosphatation Only / 300ppm / 450ppm
Phosphatation WITH Adsorbent / 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:
- Flow rate of maximum of 45m3 per Hour
- Brix of Filtered Liquor at 58 to 60
- Average Color Removal in Carbonatation Process of about 50%, with Raw Melt Liquor at 1650 IU and Filtered Liquor at 825 IU.
- 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:
- Flow rate was maintained at 50m3 per hour (about 11% increase)
- 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.
- 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
ProcessMethod / High Color Sugar/VHP Mix Ratio / Process Flow Rate / Filter Cycle / Filtered Liquor Color / Color Removal Melted vs Filtered / Refined Sugar Output(%) / (m3/hr) / (Hours) / (IU) / (%) / Increase / Ton/day / Increase
Carbonatation Only / 5 / 45 / 5-6 / 830 / 50 / -- / 688 / --
Enhanced Carbonatation / 20-30 / 50 / Up to 7 / 670 / 72 / 22% / 785 / 14%
The applications of the High Performance Adsorbent Products resulted in 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 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: A Processing Perspective”.2001. Comparison of Processes. pp. 334
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