TROPICANA, BRADENTON, FLORIDA
INNOVATIVE MECHANICAL WATER TREATMENT FOR THE
NORTH CONDENSER SYSTEM EVAPORATIVE CONDENSERS
NREP/2005 ENVIRONMENTAL AWARDS
MAY 31, 2005
PREPARED BY: TONY LUNDELL
TROPICANA - BRADENTON, FLORIDA
NORTH CONDENSER SYSTEM PROJECT OBJECTIVES The Tropicana North Condenser System, (NCS) in Bradenton, Florida, was constructed with several key objectives in mind. These objectives were to: (a) provide a, state-of-the-art facility which cools one of the largest refrigerated enclosures in North America, (b) improve condenser operating efficiency over the existing central and south condenser systems (c) conserve water by minimizing condenser make up consumption, (d) produce a reduced quantity of condenser bleed that possessed minimal pollution and (e) implement environmental improvements and worker safety wherever possible. The designers, Tropicana Bradenton Management, and Tropicana Bradenton Operating personnel embraced these core objectives. Numerous environmentally friendly, water-saving and waste-minimizing programs were considered in this endeavor. One of these programs included the VRTX Technology, a patented and innovative, chemical-free system for treating Tropicana Bradenton's North Condenser System, (NCS). The project objectives for the VRTX system were as follows:
• Performance equal to or better than traditional methods of chemical treatment on the evaporative condenser water that rejects heat from the ammonia compressor system.
• Reduce or eliminate toxic and hazardous chemicals and improve worker safety and environmental compliance.
• Significant water savings. Measurement to be via cycles of concentration and reductions in makeup and blow down.
• Corrosion control equal to or less than Cooling Technology Institute (CTI) recommendations.
• Scale control equal to or better than those achieved from traditional chemical water treatment.
• Biological control equal to or better than CTI recommendations. • Justifiable project cost savings. • Ability to generate a reusable water source for non-potable applications from the
bleed. • The on-site ability to compare the VRTX system with chemical treatments.
PROJECT RESULTS: Installation of the VRTX system on the North Condenser System has yielded the following results:
• VRTX system performance met or exceeded that which would be accomplished by using conventional chemical water treatment methods.
• Shortly after startup on the NCS, the VRTX system eliminated the use of hazardous chemicals (biocides, algaecides and corrosion inhibitors) in the NCS condenser water. Worker safety was improved, training requirements were reduced, storage of onsite water treatment chemicals were eliminated for this system, along with the improved work environment for employees and environmental compliance associated with this benefit.
• Annual water savings exceed 5 million gallons (see Appendix A). • Corrosion rate test results were within the Cooling Tower Institute Limits:
• The annual cost savings for the VRTX portion of the project is in excess of $100,000 and the VRTX portion of the project was paid off in less than 26 months, (See Economic Analysis Section).
DETAILED DISCUSSIONS: Background The Tropicana facility in Bradenton, Florida, is a state-of-the-art facility designed to keep citrus & juice products cold. The facility's state-of-the-art North Condenser System (NCS), has the capacity to handle 15,000 tons of ammonia refrigeration. It is the one of the largest refrigeration systems in the North America. The North Condenser System is an essential component of the ammonia refrigeration system that is responsible for keeping the perishable products at the Tropicana, Bradenton Facility cool and fresh. Water is pumped from a sump basin at the base of each evaporative condenser to a system of spray headers positioned above the ammonia condenser tubes in each evaporative condenser unit, see (Figure 1). The spray water is discharged over the horizontal bank of tubes from top to bottom and a counter current flow of air is induced upward through the water flow by the evaporative condenser fans, see (Figure 1). This process allows the heat from the high pressure/high temperature ammonia vapor to condense to a high temperature/high pressure liquid inside the condenser tubes where it then travels thru an expansion valve after it exits the evaporative condenser tube bundle. See (Figure 1). The ammonia is then cooled as a result of the pressure drop it experiences across the expansion valve, and that “cool-ness” is passed to the refrigeration area of the facility, See (Figure 1). Makeup water is added to the condenser sump basin to compensate for water losses due to evaporation, drift, and bleed. Bleed is the discharge of water to the sanitary sewer system or plant reuse when the concentration(s) of scaling components within the condenser water are above saturation in the condenser water system. Traditionally, chemical treatment of the makeup water is required to control scale, corrosion and biological activity. The Bradenton facility had identified the North Condenser System, (NCS), for evaluating VRTX technology. The North Condenser System, (NCS), consists of a bank of 18 evaporative condensers, (EC’s), with a 15,000 ton cooling capacity. The water treatment committee at the Tropicana, Bradenton, Facility managed the VRTX project. This committee began their task by seeking the best available technology and then establishing the goals, objective and performance measurements. The emphasis was on operational efficiency, environmental compliance, water conservation, and improved worker safety. Project Resolution
Since the early 2000's, Tropicana Management and operating personnel at the Bradenton facility had researched alternative cooling water treatment methods to replace traditional chemical treatment for the evaporative condensers. Like most companies, Tropicana uncovered several non-chemical methods available in the marketplace and concluded that none of these would accomplish the aforementioned goals. During the course of their continued evaluation and search, they were informed that one non-chemical treatment system, VRTX, had merit and should be considered for use at the Bradenton facility. Shortly thereafter, Tropicana made an Inquiry to VRTX Technologies, LLC, after which the VRTX technology was presented to Bradenton personnel with the claim that the technology was able to control scale, corrosion, and microbiological activity in evaporative condenser water systems without the use of chemicals. In addition, the condenser water system could be run at elevated cycles of concentration so that makeup water usage and bleed water volume would be reduced. Moreover, VRTX had a proven track record in numerous installations throughout the United States, notably in evaporative condensers. A number of Blue Chip companies were utilizing VRTX technology. After checking independent references and reviewing the independent party data, the Bradenton committee elected to install three VRTX 250gpm units and the specified filtration systems on the North Condenser System. System Design: The Tropicana Bradenton facility purchased and installed three 250gpm VRTX systems (VRTX unit and filtration system) to the sump basin water that serves the NCS. A Zero Gravity Filtration System, ZGF was installed on the main condenser basin to separate and remove precipitated solids from the condenser water stream. The VRTX system ran under the same load & conditions as the previous chemical programs used prior to VRTX. The makeup water for all systems was the same. The VRTX system was installed on new evaporator condensers. Prior to final startup the evaporative condenser system watersides were passivated. Throughout the evaluation period, the committee utilized independent lab data as well as VRTX lab data to measure performance. Summary of Results: Since startup, the VRTX system has yielded significant water savings, along with the option to reuse large quantities of non-potable water. Corrosion control was below
Cooling Tower Institute, CTI standards. There was little or no scale buildup on the critical heat exchange surfaces, and the VRTX system was able to control microbiological activity below CTI specifications. Scale Buildup No significant scale buildup was observed in the systems treated by the VRTX system (See Appendix C). Frequent visual inspections, Delta T’s, ammonia head pressures concluded that no measurable heat transfer efficiency loss since the VRTX technology has been treating the NCS. It should be noted that the makeup water at the Bradenton facility is reasonably aggressive, as noted in the water analysis contained in Appendix A. Nevertheless, the VRTX system was able to operate, on average, at cycles of concentration above 8.5 without any scale buildup. This is compared and contrasted to chemical treatment systems operating at 5.9 cycles of concentration. Microbiological Control Microbiological counts averaged less than 350 RLU’s or ~ 10,000 CFU/ml for this system. No significant bacteria slime was noted on the evaporative condenser tubes. Relative Light Units are a measurement of Adenosine-Tri-Phosphate, (ATP) which is the molecule that all cells use for respiration and other life processes. More bugs equals more ATP, which translates to more microbes per volume in the condenser water. Colony Forming Units Per mL is another unit of measurement that is used to quantify microbes in the recirculating cooling water. Corrosion The results for corrosion coupon testing are contained in Appendix B. No pitting was noticed on any test coupon. On galvanized steel, the corrosion rates were good to excellent for passivated and non-passivated galvanized coupons. Environmental Impact Appendix A summarizes meaningful and significant water conservation. As noted, annual water savings are over 5.4 million gallons of water. Moreover, the use of the VRTX system has allowed over 7 million gallons of non-potable water to be reused on an annual basis. The major water savings from the use of the VRTX system comes from increasing the cycles of concentration without causing scale, corrosion and microbiological problems. The reduced makeup water usage comes from the reduction of blow down discharge at Bradenton. The VRTX systems operate at 9 cycles versus 6 cycles for traditional chemicals.
Use of Hazardous Chemicals The VRTX system has eliminated the use and release of the following chemicals into the environment: Low Molecular Weight Anionic Polymer, Phosphonate, Tri-Toly-Azole, Molybdate, Zinc, Tin Butyl Oxide Biocide and Chlorine / Bromine Oxidizing biocide. Not only have the water based pollutants from these treatment chemicals been removed from the environment but the Volatile Organic Compounds, (VOC’s), released to the atmosphere during the chemical manufacturing process and those released during their use have also been eliminated. Economic Analysis Use of VRTX technology has proven that an effective control can be maintained without the use of chemicals and the problems of scale, corrosion and bacteria can be controlled. Since utilizing the VRTX system, the annual cost savings have exceeded $100,000 per year and the ROI was achieved in less than 26 months. Note the following: Reduced Chemical Usage $50,000 Water Savings $13,000 Sewerage Cost Reduction $69,000 Routine Purchase Processing $ 5,000 Total Annual Savings $137,000 In addition to the tangible economic benefits above, the following would be included:
• Eliminated risk of water treatment chemical spills for this system. • Improved employee work environment to eliminate handling of hazardous water
treatment chemicals. • Elimination of the discharge of hazardous water treatment chemicals to the
environment from the NCS. • Continued positive employee relationships as a result of management and
empowered employees to identify, evaluate and use new technology to improve their work environment and the surrounding community environment.
Innovation Tropicana and the Bradenton facility have always stressed innovation and the use of the best technology whenever possible. The VRTX project proved to be innovative and beneficial for the following reasons:
• The program was responsive to Tropicana's desire to conserve water and reduce exposure and use of hazardous chemicals and biocides
• The project addressed an operational area which was not a typical area for environmental improvement or cost saving opportunities -- both of which proved to be beneficial
• The project utilized key personnel from the Bradenton facility along with personnel from the VRTX organization and the Stellar Group
• The project identified and qualified a new mechanical, chemical-free treatment of cooling water while improving system operation efficiency, reducing hazardous material handling by employees, reducing plant water usage, reducing plant energy usage and reducing chemical waste to the environment
Model for Others Installation of the three 250 gpm VRTX systems at the Tropicana Bradenton facility has proven to yield significant savings and benefits for the plant environment as well as the surrounding community. Several other private and public entities that utilize water-cooled systems are in the process of reviewing and installing the VRTX technology to accrue the environmental and economic benefit that this technology provides. *****************************************************************