Condensate recovery, a challenge for water management
Approximately 80% of the water that enters with the cane to the sugar factories can be recovered in condensed form and used in different stages of production.
Like almost every living being on the planet, sugar cane is made up of 70% water, which means that a similar percentage enters the sugar manufacturing process with the cane.
Now, since water is essential in different phases of sugar production, it is necessary to make rational use of what enters with the cane to reduce its capture from external sources.
But, how can this water be used and what is the most efficient way to reuse as much of it as possible? If so, does the resource meet the optimal conditions to be used multiple times in the process?
To answer these and other questions, in mid-2013 the sugar sector created the Mesa del Agua en Fábrica working group, which started different activities. One of them was to calculate the gains and losses of water in the sugar production process, with which it was identified that the highest water requirements occur in the plant vapor condensation system; in other words, when the water that is part of the sugarcane juice evaporates and later condenses.
These vapors are used as a source of thermal energy in the process and some of the already condensed plant vapors are capable of being recovered for use in other stages of the operation.
According to Diego Cobo, Cenicaña mechanical engineer, studies carried out by Cenicaña have confirmed that “approximately eighty percent of the water that enters the sugar production process with the cane can be recovered in the form of condensates from the process. –And it needs–: Among the possible uses of these recovered condensates we can mention: imbibition of bagasse in the grinding process; replacement of boiler feed water; preparation of chemical inputs; ash wetting at the equipment outlet, such as cyclones at the steam generation station; replacement of water in closed circuits, such as condensation systems, swimming pools or cooling towers; washing and cleaning of floors, and cooling fluid in mill shaft supports, among others ”.
This means that the rate of water collection from natural sources and the generation of effluents can be reduced in the appropriate way.
These first studies made it possible to identify opportunities for improvement and implement actions that have been validated in some mills with very good results.
In fact, the resource management carried out in each mill through the Factory Water Board was reflected in a decrease in the water catchment indicator in 2013 and 2014, which went from 1.41 m3/ t cane at 1.35 m3/ t cane, which is equivalent to approximately 1,186,000 m3 water.
An alternative to improve the work of control, distribution and monitoring of condensed water to be reused in different stages of the production process is to implement a centralized system, which works as a main tank for water collection. The condensate flows are conducted to this tank, and with the installation of cooling towers its temperature is lowered to later use this water in the factory.
In addition, it is essential to control the quality of the recovered condensate by recording its physicochemical variables to project its possible uses. In this sense, Cenicaña has validated nine methodologies to determine the water quality parameters, which are available to be adopted by the mills.
“The Factory Water Table has allowed committees from different mills to discuss and propose solutions to various problems related to the optimal use of water resources, and good proposals have emerged from them for a greater and better use of condensates, since according to the quality of the fluid can be suitable for different uses, such as: feeding boilers for steam production, exhaust steam tempering, imbibition and preparation, among others ”.
David H. Giraldo Jaramillo
Maintenance Supervisor - Elaboration Ingenio Pichichí.
Energy expenditure and water consumption
Condensation technology is a factor that affects energy and water consumption in liquid injection stations, and therefore the design and configuration conditions of the system are essential for a good performance of the process.
According to the engineer Diego Cobo, it is essential that the barometric condensers are located at an appropriate height for atmospheric pressure conditions, so that only the energy required to raise the injection flow is used.
In addition, the water consumption in the condenser can be reduced by controlling both the temperature and the flow of the water at the outlet of the condenser, so that the amount of water that enters the condenser is proportional to the evaporation rate inside the equipment.
Article: Use and reuse of water in the sugar manufacturing process. Available in: Library catalog.
Presentation: Water balance project progress. Available in: Factory Committee reports, March 5, 2014.