Raw sugar factory and refinery practice at Central Azucarera Don Pedro, Inc. (CADPI) : special topic: process control in pan boiling crystallization and purging

Date

10-2011

Degree

Bachelor of Science in Chemical Engineering

Major Course

Major in Sugar Technology

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Jeanne Michelle T. Valencia

Abstract

The need for raw and refined sugar in the Philippines has increased over the past decades due to the establishment of industrial parks that cater international companies in need for high quality sugar for their production. In order to meet the demands of both local and international market for high quality sugar, many sugar companies improved their sugar production techniques, which involved installation of new equipments and plant expansion projects..Central azucarera Don Pedro, Inc. (CADP,Inc) located in Nasugbu, Batangas is one of the largest sugar factory in the Philippines with a capacity of 13000 tons of cane per day. The company had an expansion program during C.Y. 2010-2011 to increase its capacity to 15000 tons per day by adding new equipments in the raw sugar factory and modernizing the refinery operations. Also, the company helps the planters increase their farm yields in terms of tonnage and sugar per hectare which will consequently increase sugar production. Production starts at with cane preparation and milling.. The discharged canes flow through a series of size reduction equipments in preparations for milling. Prepared canes go into a milling tandem where juice is extracted. The juice is sent to the boiling house for further processing while the residual matter (bagasse) is sent to the Boilers to be used as fuel. The juice first weighed in order to determine the amount of process material entering the boiling house. After weighing, the juice passes through a series of heaters in order to raise its temperature to 216-220°F. Before the juice enters the tertiary heater, a lime saccharate solution is added that raises the pH of the juice to avoid sucrose inversion. Most of the impurities present in the juice are removed during clarification in which the heated juice goes into a clarifier where the impurities settle at the bottom. the clarified juice is sent to a quituple effect evaporator system that removes around 80% of the water present, while the impurities or mud goes to a rotary vacuum filter for sugar recovery. The concentrated juice from the evaporators (called syrup) then goes to the pan boiling station to start the crystallization process. After pan boiling, both high and low grade massecuite undergoes further formation inside crystallizers. The massecuite then goes into a centrifugal machine to separate the sucrose crystals from the mother liquor(Molasses). The collected raw starts with weighing of raw sugar which is then discharged on screw conveyor leading to the mingler, which removes the thin film of molasses present on the crystal. The resulting material, called magma, is discharged into the centrifugals to separate the affined sugar from the affined syrup. The affined sugar is brought to the melter and mixed with sweet/hot water. The resulting raw melt is brought to a lime liquor tank where it is added with milk of lime before it goes to the carbonators, in which CO₂ gas is added and reacts with the solution. The carbonated liquor is filtered to remove the solid particles, and the resulting brown liquor is then brought to the IER to remove colorants. The resulting fine liquor undergoes evaporation, pan boiling and centrifugation similar to that in the boiling house. the process only differs in the feed material since refinery operation only uses syrup in white pan boiling straight pan boiling) compared to refinery operation only uses syrup in white pan boiling scheme with recycles. The sugar then goes into the driers to reduce its moisture content and then blended according to their specific grades. Screened sugar are discharged in 50-kg or1-ton bags for packaging and then brought to the warehouse for storage. In order to monitor the quality of their products, CADPI has quality control department divided into three laboratories: raw, refinery, and research laboratories. Samples of intermediate products like juices and molasses as well as final products are brought to the laboratory for analysis. Wastewater analyses are also done to monitor the quality of the discharged water. The wastewater of the factory is treated in the Environmental Management System department (EMSD) that complies with the DENR standards for wastewater discharge. EMSD uses a system of lagoons as primary treatment for the wastewater capable of treating cubic meters per day. The waste treatment plant lowers the BOD, color, salinity of the wastewater before discharge. According to Dunn (2006), the technology of controlling a series of events to transform a material into a desired end product is called process control. Consequently,process control strategies are the key factors to maintain efficient production and a safe working environment for the workers. The same is true for sugar factory operations in which process control strategies have evolved from manual control practices to computer aided monitoring devices. In CADPI, both manual and automatic process control are employed in pan boiling control. Ten batch vacuum pans operated manually by skilled pan men while three continuous vacuum pans are fully automated. Basic batch vacuum pan control is achieved through the use of valves and gauges that aid the operator in determining whether the process is still desirable or not. For automatic control, CADPI installed a NAHMAT pan automation system in the white vacuum pans in order to achieve a more precise crystal growth and formation. Continuous vacuum pan control involves the use of control loops like absolute pressure control, calandria steam control, conductivity control, seed pump speed control system and condensate monitoring system to monitor and correct any deviation from the desired setpoint. The basic crystallizer control involves the use of feed and discharge valves manipulated after achieving the required retention time for massecuite cooling, Centrifugal control can be set to automatic of manual mode depending on the quality of the massecuite and sugar. An operator can either maximum feeding time, free washing time, water washing time, centrifuging time and basket washing time to achieve a more desirable sugar washing. The use of manual or automatic control depends on the need of a particular process. In sugar factory operations, manual control is still important to properly monitor and troubleshoot a process since computer aided devices solely depend on the data stored within its system. In actual processes variations in set parameters often occur that can only be corrected manually.

Language

English

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993 2011 E62 /A36

Document Type

Thesis

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