FIRST COOLING TOWER WATER SAVINGS STAKEHOLDER MEETING

Transcription

1 FIRST COOLING TOWER WATER SAVINGS STAKEHOLDER MEETING August 25, 2010 Web conference This memo summarizes the key discussions that were held during the first Investor Owned Utility (IOU) sponsored 2011 Title 24 stakeholder meeting for cooling tower water savings. The meeting was held by Web conference on August 25 th Most of the discussion focused on the specific code change options presented and the relationship between cooling tower water chemistry and potential cycles of concentration. Section 3 provides a summary of data the project teams would like to obtain to support the water savings and cost-effectiveness analysis that will be conducted in advance of the second cooling tower water savings stakeholder meeting. For a full understanding of the scope of the code change proposal, this memo should be read in conjunction with the power point materials that were presented at the stakeholder meeting. Table of Contents 1. ATTENDEES MEETING NOTES REQUESTS FOR INFORMATION...6 1

2 1. ATTENDEES In Person: N/A On the Phone/Web Conference: Tom Carter, Baltimore Air Coil Sam McManis, Chem-Aqua Mark Pfeifer, SPX Greg Gress, ICC Jim Pegg, Evapco Chris Lazenby, Southern Company Theresa Pistochini, WCEC John Koeller, CUWCC/ Koeller and Company Angela Anderson, CUWCC Ed Osann, NRDC Jamy Bacchus, NRDC Mark Hydeman, Taylor Engineering Ron Gorman, Sempra Amir Tabakh, LADWP Tuan Ngo, California Energy Commission Stuart Tartaglia, PG&E Erika Walther, Energy Solutions Michael McGaraghan, Energy Solutions Heidi Hauenstein, Energy Solutions Jordan Shackelford, Energy Solutions 2. MEETING NOTES 2.1 Cooling Tower Water Savings This CASE report will investigate the water savings and cost-effectiveness of a mandatory standard that cooling towers in non-residential buildings be equipped with flow meters on bleed and makeup water lines, as well as conductivity controllers, overflow alarms, and possibly, drift eliminators. This CASE report is investigating the viability of a mandatory requirement that cooling towers achieve a minimum cycles of concentration based on water quality. Lastly, the CASE team proposed a possible voluntary requirement regarding water reuse for Part 11 of Title 24. Discussion regarding ASHRAE 191 P, ASHREA s Standard for the Efficient Use of Water in Building, Site and Mechanical Systems : Scheduled for a vote through the standards committee on September 16. Public review probably available in early November, and voted out in January or June. Only opportunity to get a copy is to download it when it is posted for public review it cannot be shared. Anyone who sees it posted should let Erika know and she can alert the group that it is available. 2

3 There was a discussion regarding the value of requiring drift eliminators in Part 6 (base code) versus the voluntary portion of Part 11 (green code): As far as water conservation is concerned, drift eliminators are part of blowdown. Since drift is water leaving the cooling tower, it is basically avoided blowdown. Reducing drift would require increasing blowdown to maintain CoC, so no additional savings are gained by eliminating drift. Drift eliminators are important for controlling Legionaire s disease and preventing spotting on cars; however, the purpose of Title 24 is to deliver costeffective energy savings, or in this case water savings. Drift eliminators don t contribute to that. CASE authors asked about the prevalence of constant bleed as a strategy for minimizing TDS and at what point conductivity controls are likely to be installed. Several people agreed that for cooling towers over 50 tons, a conductivity controller is going to be cost-effective. Smaller towers might be employing constant bleed, but that probably wouldn t be employed in larger towers just because it is too expensive. The group discussed typical practice for cycles of concentration seen in the field, and whether 2-4 is typical. Mary Hydeman s (Taylor Engineering) experience from the field was that over 5 cycles was exceptional Sam McManis of Chem-Aqua had records of sites where they had done business and thought the average may be higher than 2-4. Cited one location in Oakland achieving over 10 cycles. Erika had also heard of a hotel in Oakland achieving over 10 cycles using nonchemical treatment. Source was a distributor for a non-chemical treatment company. Tuan Ngo at CEC used to work with power plant permitting and recalled CTs at power plants getting cycles, even with high TDS in makeup water, which was usually tertiary-treated reclaimed water. Tuan to run down that data and share it with the group. There is no difference in HVAC versus industrial cooling towers in terms of the relationship between cycles of concentration and makeup water quality; however, cost-effectiveness threshold may be higher at power plants, allowing for more water treatment. The group discussed the value of a prescriptive requirement for flow meters in addition to conductivity controllers, and whether this was redundant. Someone commented that makeup flow meters are sufficient with conductivity meters to calculate cycles of concentration, w/o need for blowdown flow meter. Erika explained her understanding that conductivity controllers are not entirely accurate for determining cycles of concentration and that measuring flow of 3

4 makeup water over flow of blowdown was they way the chemical companies did it. Sam McManis (Chem-Aqua) agreed, but said measuring conductivity is the easiest, least expensive way to determine cycles and is okay. Mark Hydeman pointed out that flow meters are expensive probably $2,000 and it may be more cost-effective to only require it on the makeup water line. Sam thought turbine and insertion meters would be sufficient and would cost less than $1,000. A conductivity meter would cost about $400. Several people pointed out the merits of a flow meter on the bleed line, including identification of losses, managing sewer discharge costs, and raising awareness of water use in cooling tower in general especially in larger towers. Sam also pointed out that Chem-Aqua installs contacting head makeup meters that also control chemical feed if this type is not required by base code, customer would have to replace flow meters, adding cost. The group discussed the potential prescriptive requirement for a minimum cycles of concentration based on water quality. Sam McManis said that the proposed cycles of concentration requirement is not sufficient to account for water quality (proposed code references hardness and silica to set cycles requirement) it needs to account for alkalinity and other parameters. He recommended the Langelier Saturation Index 1, which accounts for ph, TDS, hardness, alkalinity and temperature, and that a maximum of would be reasonable. Ed Osann asked how operational issues are addressed in Title 24, and it was agreed they are not generally addressed. Response: Although Acceptance Testing has been added to the code since 2005, once the Certificate of Occupancy is issued, the building dept. does not do any more inspections. A discussion ensued about how the proposed Cycles of Concentration requirement could be enforced and Ed Osann suggested that water utilities could require it in their service contracts with facilities. Mark Hydeman suggested that makeup water quality could be requested from the water utility and the facility could be required to develop an appropriate Cycles of Concentration prior to issuance of Cert of Occupancy. Facility could have the option to develop an appropriate Cycles of Concentration, or meet one of two other requirements: 1) use some percentage of non-potable water for makeup source, or 2) reuse some percentage of blowdown water, e.g., for landscaping. 1 The Langalier Saturation Index (LSI) is used to predict the calcium carbonate stability of water and indicates whether water will precipitate, dissolve, or be in equilibrium with calcium carbonate. The LSI is expressed as the difference between the actual system ph and the saturation ph. If the actual ph of the water is below the calculated saturation ph, the LSI is negative and the water has a very limited scaling potential. If the actual ph exceeds phs, the LSI is positive, and being supersaturated with calcium carbonate, the water has a tendency to form scale. At increasing positive index values, the scaling potential increases. 4

5 Sam McManis agreed this could work because, generally, one of the first things a water treatment company does is get water quality data so they can determine the feasible Cycles of Concentration and develop a treatment plan for the client. Jamy Bacchus asked how we make sure the water quality report and Cycles of Concentration plan is legitimate, and Mark Hydeman responded that we could require the PE to review and sign-off on it, as had been done in other parts of the code. The CASE team asked the group whether a requirement regarding the placement of the makeup line and the bleed valve would be of value. In poorly designed systems, the makeup line can enter the sump too close to the bleed valve and water can be lost before it even circulates through the system. While people were familiar with such cases, the consensus was that they are very uncommon and the losses were minimal. The CASE team asked whether there were any comments regarding the requirement for overflow alarms. There were no objections to including this as a prescriptive requirement. The group also discussed the potential for requiring use of non-potable water as a makeup water source. Sam McManis said they are doing a study on HVAC condensate harvesting and are finding it can provide 8% of makeup water from a 300 ton system in Texas, but this depends on relative humidity since HVAC removed humidity from air as well as cools it. Theresa Pistochini with the Western Cooling Efficiency Center said they are currently doing a study on this in Davis and can share the results if they are available in time All agreed that in the dry California climate, condensate may have limited potential. Someone commented that condensate is pure, so it would be a good, but perhaps small source. Ed Osann pointed out it would also likely be cost-effective since it would require minimal plumbing from the source to the makeup line. Stu Tartaglia of PG&E pointed out that condensate is also available from refrigerated warehouses and walk-in refrigerators. Gregg Gress of International Code Commission suggested perhaps the approach to this measure code could be simplified by requiring the makeup water to be nonpotable, with an exception for those who can prove they are achieving a high Cycles of Concentration. Several people responded that having access to significant sources of nonpotable water was not the norm in California, so that would be difficult for many facilities. 5

6 3. REQUESTS FOR INFORMATION 3.1 Cooling Tower Water Savings Survey information to be requested from cooling tower water quality management companies and cooling tower maintenance companies Prevalence of conductivity controls, flow meters, overflow alarms, and drift eliminators by size category (e.g., <100 tons, tons; 500 tons or greater) Typical practices by size category Conductivity setpoints for blowdown Cycles achieved Prevalence of constant bleed Survey information to be requested from cooling tower manufacturers Market share of system sizes by market sector Additional useful information regarding water reuse in cooling towers Case studies/ feasibility studies Water quality for various sources of reused water - including but not limited to, HVAC and steam condensate, captured rainwater and stormwater, tertiary treated reclaimed water, cooling tower/ boiler blowdown water - and treatment requirements for use as cooling tower makeup water Treatment requirements for use of cooling tower blowdown for principal applications, i.e., landscape irrigation, toilet flushing. Onsite water treatment options and costs 6