1、 Michael P. Patton is the International Sales Manager for Griswold Water Systems, Corona, CA, USA. The Debate is Over: Physical Water Treatment Meets the Demands of Modern Water Treatment Deliverables Michael P. Patton Member ASHRAE ABSTRACT Awareness of Non-chemical processes and the successes of v
2、arious technological solutions to common water treatment problems are now well established. Despite detractors, Non-chemical and Physical Water Treatment products continue to make their mark by providing results that meet and exceed water treatment industry standards. Although initially propelled by
3、 the greening of the built environment, Physical Water Treatment now stands as a viable alternative to traditional chemical programs. The debate over whether these technologies work is over, with the new discussions centered around when and how to apply them. With technological progress and continue
4、d innovation, these once experimental technologies have given birth to experienced and proven methodologies. This paper covers the history of various technologies, and examines the plusses and minus of each class of non-chemical water treatment. It will illustrate how the latest advancements are sav
5、ing of water and energy, while matching or exceeding the performance metrics of modern water treatment deliverables. INTRODUCTION In the debate over the efficacy of Physical Water Treatment (PWT) systems to provide commercial cooling water treatment results that are on par with additive chemical pro
6、grams, skeptics abound. Despite the multiple field trials that have been documented over the recent decade, consensus among chemical water treatment providers is elusive as to whether these technologies are suitable for any given commercial application. All water treatment programs are subject to fa
7、ilure if ignored or improperly applied, yet skeptics constantly direct attention to specific instances of in-situ PWT performance failure, while cases of failed additive chemical programs are forgotten. Often in the case of failure, a PWT manufacturers service recommendations were ignored, and sound
8、 forensic evaluations of failure are dismissed. Even though PWT programs do not operate on the same principles as additive chemistry programs, properly executed PWT programs achieve results on par with modern water treatment deliverables. Since the year 2000, there have been more and more peer revie
9、wed papers, case studies, and success stories. Growing acceptance by the WT Industry of performance parameters is evident. However, not all PWT technologies operate under the same physical principles, and performance against accepted criteria has been spotty. COMMON PWT TECHNOLOGIES AND PRINCIPLES H
10、uchler (2002) originally organized PWT systems into three classes of technology; Magnetic, Electrostatic, and AC Induction and laid out the principals of each. In the intervening years, advancements in AC Induction class to now include Pulsed Electric Field technology and the addition of a new class
11、 of PWT; Hydrodynamic cavitation. All of these technologies claim efficacy in preventing scale, microbiological populations, and corrosion inhibition. Other classes that do not claim all three have been dismissed from this evaluation. Table 1. PWT Technologies and claims for water treatment principl
12、es Principle Scale / Deposition Micro Bio Corrosion Fixed Magnet Magnetic field Bulk precipitation Nutrient limitation Alkaline water chemistry Electrostatic Direct electric field Bulk and/or Charged surface precipitation Electric field bio stasis Reduction of MIC AC Induction / Pulsed electric fiel
13、ds Induced electric field or Electrodynamic field Colloidal precipitation Encapsulation / Electroporation bio stasis Alkaline water chemistry, carbonate saturation Hydrodynamic Cavitation Kinetic energy waves Bulk Precipitation Membrane rupture biocidal Alkaline water chemistry At the time, Huchler
14、also identified “Obstacles to Advancementi” and laid out parameters for field trials that should be undertaken by manufacturers of PWT. More than a decade later, examples of these field studies have been executed and are examined herein. PWT PERFORMANCE METRICS Examination of PWT performance metrics
15、 related to modern chemical water treatment deliverables allows a construct of comparison of performance of the two approaches. Micro-biological control is measured by heterotrophic plate count (HPC) according to Standard Methods for the Examination of Waste Water (SMEWW Vol. 22) section 9215B. Usin
16、g plate count agar (PCA), the standard applied is often less than 104 cfu/mL (colony forming units per milliliter of water) to achieve satisfactory results. For control of surface biofilms, (sessile) there is no consensus on neither quantitative nor qualitative examinations. SMEWW and ANSI are silen
17、t on techniques for sampling and enumerating sessile populations in the field. Lacking guidance on how and where to sample, and further, how to assay and report, general guidance of 106 cfu/square cm is often required for modern water treatment program RFQs. At 106 cfu/cm2 sessile populations are vi
18、sibly present and can be clearly evaluated by touching exposed and accessible wetted surfaces for slimy feel on the fingers. The effects of deposition and scaling are well known, but absent precise controls, visual examination is the norm. Precise control by monitoring of heat transfer by full-load
19、chiller condenser approach temperature (Leaving condenser water temperature (LCWT) minus condensing saturated refrigerant temperature) is more available today given the sophistication of chiller machine controls. However, operating condenser approach temperatures can be misleading at less than full-
20、load. Each chiller machine will have a different approach temperature ranging from less than .5degC (0.9degF) to 4degC (6.8degF) depending upon tube type, tube size and machine age. Only full load design condenser approach should be evaluated against approach temperature as catalogued by the manufac
21、turer. The resulting performance goal of observing deposition in visible areas of cooling tower fill, while operating or after light brushing of chiller condenser tube maintenance is the most common evaluation of success. Uniform corrosion performance depends upon the analysis of corrosion coupon te
22、st results, performed at 90-day intervals. General attack is calculated relative to coupon weight loss, yielding 0.0254mm (0.001 inch) annual rate of metal surface loss, or one mil per year (mpy). Though there is much debate on the topic, for HVAC Chemical Engineering, pp66-69, April 2008 Huchler, L
23、.; (2002); Non-chemical Water Treatment Systems: Histories Principles and Literature Review, IWC-02-46 Cho, Y.; (2002) Efficiency of physical water treatment in controlling calcium scale accumulation in recirculating open cooling water system. ASHRAE Research project RP-1155, Final Report. Cho, Y. e
24、t. al., (2005) Pulsed-power treatment for physical water treatment, Int. Comm. Heat Mass Transfer, 32, 861-871 ASHRAE Handbook 2015 Applications - Chapter 49, p49.8. Kitzman, K., et. al., Blumenschein, C., Smith, A., (2003) Chemical vs. Non-chemical Cooling Water Treatments a Side-by-side Comparison
25、; IWC Conference Paper 03-22 McLachlan, D., (2008) Physical Water Treatment for Cooling Towers; CTI annual Conference Paper TP08-15 Alley, D., Puckorius P., Keinle, H.; (2008) Dolphin Pulsed Power Cooling Water Treatment; CTI Annual Conference Paper TP08-19 Patton, M., Alley D., (2009) A Field Evalu
26、ation of Chemical and Pulsed Power Water Treatment; IWC Conference Paper 09-60 Puckorius, P., (2012) Field Evaluation and Verification of Biological Control in Operating Cooling Tower Water Systems Utilizing Non-Chemical Pulse Electric Field Devices; 2012 CTI Annual Conference Paper 12-10 Puckorius,
27、 P., Dresty J.E. Jr., Ruckstuhl, R., Jr.; (2014) A Detailed Independent Field Site Evaluation of Electrodynamic Field Generation Results as the Cooling Water Treatment; 2014 CTI Annual Conference Paper 14-18 Puckorius P., Ruckstuhl, R., Jr.: (2015) A Progress Report of a Field Evaluation of a Cooling Tower System and the Effectiveness of an Electrodynamic Pulse Field Water Treatment; 2015 CTI Annual Conference Paper 15-10
