Archive | May, 2005

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May 1, 2005
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Chiller Energy Efficiency Cuts Energy Costs

When Saint Francis Hospital was founded in northeastern Oklahoma in 1960, it was a 275-bed facility. It has grown into a facility licensed for 918 beds. Saint Francis’ traditions of excellent patient care, continuing education, and clinical research have made it stand apart. These traditions of excellence and leadership also hold true for the Saint Francis facility maintenance department.

The chiller plant at the hospital consists of three older 1920 ton Carrier and three newer 2000 ton York centrifugal chillers, totaling 11,760 tons of cooling capacity, along with a five-cell, 10,000 ton Marley cooling tower system with variable speed fans. The facility uses a total of 1300 tons of free cooling capacity through plate exchangers during the winter. The plant runs four 6000 gpm variable speed chill water pumps to create a secondary loop to the hospital, which increases overall efficiency by maximizing flow without bringing additional chillers online.

Commitment to excellence
Operators endure a three-year apprentice program, proceeding from limited experience to licensed operators of a chiller/boiler plant (a requirement of the City of Tulsa) to a first class unlimited licensed operator. This process provides additional training coordinated by hundreds of years combined experience in the maintenance department.

To ensure the facility maintains high performance, it uses automation where economically feasible. This includes direct digital controls (DDC) in the chiller plant along with state-of-the-art automated equipment to help manage the water treatment program. The chillers are sequenced to ensure the cooling load is met with the least amount of equipment in operation. Equipment operates near full capacity when possible, but averages 60-80 percent load, rarely falling below 50 percent. To help further reduce the kW/ton for each chiller, the entering condenser water temperature (ECWT) is dropped to its lowest possible temperature based on wet bulb and design conditions.

Accurate analysis needed
Committing to best practices and the need to save time analyzing log sheet data, the maintenance department was interested in an easy-to-use, cost-effective tool that would evaluate log data, trend and verify chiller performance levels, and provide cost analysis. In late fall 2003, Saint Francis contracted to beta test an Internet-based chiller energy efficiency tool developed by Efficiency Technologies, Inc. (EffTec), Tulsa, OK, called EffHVAC. The operators input their daily chiller logs into the tool, which calculated the chillers’ performance and compared kW/ton to full load design conditions to determine efficiencies, tonnage, and costs. It was immediately apparent that it was difficult to determine actual chiller performance by comparing to full load design. The results were an exaggerated efficiency and inaccurate cost analysis.

Realizing the impact that ECWT and part load values have on chiller efficiency, the company developed a proprietary calculated part load value (CPLV) that increased the predictability of the kW/ton for a chiller under all conditions. CPLV kW/ton is compared to the actual kW/ton produced by the chiller, resulting in accurate efficiency measurements and cost analysis.

Along with this improvement, advances in charting and data collection make it possible to view and verify the slightest changes in operations that affect efficiency. Other improvements to the program include chiller alarms, comprehensive troubleshooting guidelines, and water usage calculations. The troubleshooting guidelines help identify problems such as defective temperature sensor and pressure gauge. The water usage calculations determine the facility’s projected evaporation credits and cycles of concentration in the tower system, further improving overall plant cost analysis.

Baseline data
Taking past chiller logs and entering the data into the energy efficiency tool establishes a starting point for current analysis. Any improvements or operational changes, past or present, are immediately reflected for review. Log sheet data was input for 2003 and the reports were compared to the reports for 2004. This increased awareness and improved general operations such as ECWT adjustments, gauge and sensor calibrations, scheduled maintenance, monitoring weather conditions, and adding/shedding chillers. Two other significant operational changes that improved efficiency were flow adjustments and changing the chiller configuration.

Identify electrical/mechanical problem
The reports have helped identify an electrical problem in Chiller #5 that may have gone undetected indefinitely. The chiller was sporadically unloading and having difficulty loading. By examining the reports (Fig. 1) it was obvious that the condition was having an effect on the kW/ton and daily operation of the chiller. This chiller had been taken off line several times after this condition was diagnosed. Replacing an automatic refrigerant level controller corrected the problem.

Biocide sterilization, cleaning
Microbiological organisms can have a tremendous effect on heat transfer. It is not uncommon for their impact to cause a 10-15 percent reduction in efficiency, and even more in extreme cases. On July 20, 2004, the plant operators performed a routine scheduled tower/condenser sterilization which included hyperchlorination and biodispersants to strip away all biofilms in the tower/condenser system. The overall efficiency improvement is noticeable on the monthly calendar report and is a 2-3 percent improvement in efficiency system-wide (Fig. 2).

Monitoring weather conditions
The effects of dramatic weather change can immediately be seen in the reports (circled in gold Fig. 6). On July 9, a storm blew in an unusual cold front between 12:00 and 14:00 (military time), dropping the temperature 17 F. This dropped the kW/ton in Chiller #1 6.8 percent and dropped the ECWT 7 F. The kW/ton in Chiller #6 dropped 6.3 percent, and the ECWT dropped 6.9 F.

Adding, shedding chillers
To determine when a chiller should be added or shed, if the efficiency is improved when a chiller is added, the chiller should have been added sooner. If the efficiency falls, the chiller was added too soon. This is authenticated by analysis of the reports. In Fig. 3, the circle represents the impact on Chiller #1 by the addition of Chiller #5 at 09:30 and shed at 15:00. The introduction of Chiller #5 dropped the efficiency of Chiller #1 from 76 percent to 52 percent at 10:00; it returned to 79 percent efficiency at 12:00. The impact is temporary and the system should adjust after a short period of time provided the system load increases. The shedding of Chiller #5 was appropriate indicated by the minimal impact on the kW/ton of Chiller #1.

Flow adjustments
It became apparent from analyzing the reports that the chiller system flow had become out of balance due to seasonal adjustments (additional chillers were brought on line in April). Fig. 4 shows the efficiency of Chiller #1 prior to any adjustments in the flow rates. On July 8 between 08:00 and 10:00, flow valves for the chiller were adjusted and measured by a DP gauge to achieve design flow rates.

The results were immediately apparent in increased efficiency (Figs. 5and 6) and lower costs (Fig. 7). The increase in efficiency for the chiller was approximately 17 percent, cost avoiding approximately $144/day in energy. The awareness gained from this experience makes it possible to anticipate and adjust to the effect seasonal changes have on flow rates.

Load profiles
In 2003, the #5 Cooling Tower was down for repairs, limiting the use of Chiller #6. In 2004, the repairs were completed, allowing the full use of Chiller #6 (Fig. 8). This increased the flexibility of the plant and reduced the demand on the older, less efficient chillers. The plant load also increased approximately 23.7 percent to 23,074,439 tons through October, which included the addition of a new complex. Using the more efficient chillers and decreasing the use of the less efficient chillers helped lower the overall plant electrical costs while meeting the increased cooling demand.

Chiller-specific improvements
Table 1 shows a comparison of the improvements made on the individual chillers from January through October 2003 and January through October 2004. The total chiller specific cost avoidance through October 2004 is $67,110.

Total plant improvement
These overall plant improvements have resulted in substantially lower energy costs. From January to October 2003, the plant produced 18,650,119 tons of cooling at a cost of $667,880 ($0.0358/ton). From January to October 2004, the plant produced 23,074,439 tons of cooling at a cost of $726,066 ($0.0314/ton)—a $100,373 cost avoidance in energy usage. Subtracting from this the cost avoidance from chiller-specific improvements of $67,110 shows $33,263 from modifying the chiller configurations.

For a not-for-profit hospital that operates on a 2 percent profit margin, $100,373 in cost avoidance is equivalent to bringing in $5,018,650 in new business. The total energy cost avoidance through 2004 is conservatively expected to be more than $120,000. The continual improvement through 2005 is expected to yield even greater results.

The investment in the on-line tool was $3000 in 2004, which was recouped in approximately 9 days of energy cost avoidance. This tool has allowed management to accurately evaluate chiller performance and enabled plant operators to refine the best practices for their plant.

Future improvements
Based on the operational achievements, plans to increase efficiency and reduce energy costs are being developed. Knowing the relationship between flow and efficiency will allow the operators to monitor chiller performance and make immediate adjustments to ensure optimal efficiency. Chillers will be added and shed with greater predictability, minimizing unnecessary energy consumption. Load profiles associated with real-time energy pricing are being studied to determine potential cost avoidance and impact on plant operations.

Information supplied by Don Clark, Efficiency Technologies, Inc., 3105 East Skelly Dr., Ste. 420, Tulsa, OK 74105; telephone (866) 333-8321

0505chiller1

Fig. 1. kW/ton spikes on Chiller #5 associated with an electrical/mechanical problem.

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Monthly Calendar Report

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Fig. 2. Biocide sterilization and tower cleaning impact for Chiller #1.

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Fig. 3. Impact on Chiller #1 when adding Chiller #5.

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Fig. 4. Chiller #1 before flow adjustments.

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Fig. 5. Chiller #1 during flow adjustments.

 

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Fig. 6. Chiller #1 after flow adjustments.
Note: The kW/ton values scale for each chart changes, essentially zooming in for more detailed analysis when the CPLV kW/ton and actual kW/ton values get closer. For example, the kW/ton scale in Fig. 4 is from 0.55 to 0.80 and the kW/ton scale in Fig. 6 is from 0.50 to 0.675.

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Fig. 7. Calendar summary of flow adjustment results for Chiller #1.

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Fig. 8. 2003 vs 2004 chiller configuration.

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Table 1. Chiller-Specific Improvements

 

Chiller #1

Chiller #2

Chiller #3

Chiller #4

Chiller #5

Chiller #6

2003 kW/ton

0.664

0.98

0.752

0.798

0.649

0.667

– 2004 kW/ton

0.599

0.794

0.753

0.804

0.605

0.627

= kW/ton variance

0.065

0.186

-0.001

-0.006

0.044

0.04

x Total tonnage

7,332,297

1,665,375

112,744

655,459

6,923,689

3,385,875

= Total kW used

476,599

309,574

-113

-3933

304,642

255,435

x Cost per kW

0.05

0.05

0.05

0.05

0.05

0.05

= $ cost avoided/lost

$23,830

$15,479

$6

$197

$15,232

$12,772

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The Importance of CPLV

Why determine efficiency and cost using calculated part load value (CPLV) kW/ton vs full load design kW/ton? Because a chiller rarely operates at full load design conditions and entering condenser water temperatures (ECWTs) vary throughout the year. Either can greatly affect overall kW/ton.

The Air Conditioning and Refrigeration Institute (ARI, www.ari.org) has developed the measuring standard 550/590-1998 for integrated part load value (IPLV) and nonstandard part load value (NPLV). Its purpose is to reflect the chiller’s actual operating experience in the field. Depending on chiller types and compressor style, the IPLV/NPLV kW/ton can vary 10-40 percent below full load design under actual operating conditions. This ARI standard is used as a starting point for CPLV.

With this tool, CPLV analyzes full load design, actual part load, and actual ECWT to effectively calculate the outcome of what the actual kW/ton should be. The CPLV kW/ton is then compared to the actual kW/ton to determine efficiency and cost. This is more accurate than comparing strictly to full load design.

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May 1, 2005
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Winning Top to Bottom Support for Reliability-Based Maintenance

Five practical steps toward gaining a consensus for aggressively pursuing a plant-wide reliability initiative.

Whether your firm bleaches pulp for paper, refines petroleum, or manufactures, your company executives are expected to watch the bottom line. They want equipment up and running at full capacity so they can meet their output goals—even if it means pushing the equipment well beyond its original design capacity. And they want it done with an ever-shrinking maintenance budget.

These are the realities facing North American maintenance managers. So it is your job to keep the equipment running smoothly—even under these impossible conditions.

You know a reliability-based maintenance management approach can provide the solution. You have read books that explain the latest theory behind equipment failure patterns and the benefits of early detection. You have even been to technical conferences and read industry publications to learn the current reliability “best practices.”

But how do you turn your organization around? You know you will need active cooperation from everyone. But how do you get technicians, supervisors, engineers, production managers, and others to buy in—particularly when they have 20-plus years of experience in a different paradigm? And more important, how do you get executive approval to move forward with reliability initiatives?

Here are five practical steps toward gaining a consensus among your entire team for aggressively pursuing a plant-wide equipment reliability initiative.

Step 1: Educate from top to bottom
Maintenance and reliability leaders have to be much more than just cheerleaders. They have to help others understand, believe in, and follow a new maintenance approach—one that often contradicts traditional wisdom and experience. There are no quick fixes here. Traditional maintenance knowledge and beliefs have been internalized through repeated exposure and experience over many years. New concepts and practices have to be acquired the same way—with repeated exposure over spaced intervals of time. Here are some practical tips for spreading the “reliability gospel” in your organization:

• Shatter the old myths. For example, as reliability leaders, we know that overhauling or replacing motors on scheduled time intervals actually lowers reliability because the rebuilt or new ones are more likely to fail early in their life (infant mortality). But others in the organization may still base their understanding of maintenance on older concepts. Resistance to change will persist until they understand the limitations of traditional approaches.

• Present a better way. New concepts and methods will not take root without a clear understanding of both how and why they are better. Explain, for example, how accurate data on heat exchanger efficiency establishes what is “normal” and why timely inspections are needed to detect degradation early enough to plan and schedule corrective maintenance.

• Use multiple formats. Delivering your message via creative and varied means will dramatically reduce the number of exposures it will take for people to “get it.” Quick learning points in regular meetings, water cooler conversations, and distributing short articles can be as effective as formal training.

• Show them “what’s in it for me.” Just because people “get it” does not mean they will “do it.” So help them understand how reliable equipment benefits them personally: The production manager meets his output goal, the maintenance supervisor does not get calls in the middle of the night, and the technician gets out of firefighting mode.

Planting lots of small seeds in different places will eventually cultivate a broad understanding of reliability concepts and an appreciation for the benefits that are gained. This exposure will lay the foundation for future acceptance—not to mention approval—of real change later.

Step 2: Benchmark where you are
Obviously it takes more than education to get a plant-wide reliability initiative off the ground. Achieving marked improvements in equipment reliability requires changing how you make maintenance decisions, how you invest limited plant resources, and what people do on a daily basis. Gaining approval for this level of change requires a comprehensive plan and a strong business case. The first effort should be to assess objectively where you are now.

Benchmarking can be a humbling experience for plants that are entrenched in traditional maintenance methodologies. They are shocked to find out how far behind they are. But a good dose of reality can provide a tremendous “attitude adjustment.” It is a bit like the doctor telling you that you are 25 lb overweight, your cholesterol and blood pressure are too high, and your life expectancy is 20 years shorter than it should be. Suddenly the latest fads of eating right and exercising have a whole new meaning.

So what do you use as a measuring stick for maintenance and reliability? Unfortunately there are no industry standard metrics like we have for safety. For safety, OSHA has defined how to calculate lost time incident rate (LTIR) and recordable incident rate (RIR). Companies have been tracking them for years, so we know that an RIR of 0.5 and LTIR of 0.05 are top notch.

Benchmarking maintenance and reliability can be a bit more involved. Experts simply disagree on what to measure and how to measure it. And few industries publish their outcomes. For many plants the best answer is to enlist a professional to assess the organization. But do not spend 6 months and a ton of money. For a mid-sized maintenance organization (50-200 technicians) $30,000-$50,000 and a few weeks should get you a decent scorecard and a best practices review. The unbiased opinion is well worth the time and cost; after all, one unplanned failure of a critical pump can cost you a lot more than $50,000 in lost production and repair costs.

For those who want to implement an internal benchmarking process, a core list of maintenance and reliability metrics is provided in the accompanying “Basic List of Maintenance and Relibility Performance Metrics,” adapted from benchmarks used by the management consulting firm ATKearney. Precise definitions of these metrics vary and the “top notch” score will vary with the type of operation.

Once you know how your outcomes stack up, the next step is to assess how you are doing maintenance—a best practices review. In other words, determine what techniques or methods you are using and to what extent. Examples of top notch practices include operator-driven maintenance, designing out failures, condition-based maintenance, and use of an enterprise reliability information system. If you do all the right things and do them well, you should achieve good results. So make sure there is good correlation between your best practices “score” and the performance outcomes “score.”

Communicating the results of a benchmarking effort to the organization can be risky business, particularly when the gap between perception and reality is great. But an early wake-up call can energize the organization and possibly save a plant from being closed.

Step 3: Establish a long-term vision
Once you have established where you are, your next challenge is to define where you want to be. The key to establishing a vision is to begin with the end in mind. Use the metrics from the benchmark to set specific, measurable targets for your performance outcomes 3-5 years in the future. Use the best practices from the benchmark to paint a vision of what maintenance and reliability will look and feel like when you get there.

Make sure you include the key stakeholders in the goal-setting process. Maintenance supervisors, engineers, reliability specialists, and production managers will all have to cooperate to achieve the goals. An offsite planning meeting can be a very effective forum to gain commitment, motivate your team, and establish momentum for your reliability program. And an outside resource can be helpful as a neutral facilitator of the process.

During the visioning process avoid getting mired in discussions of the details and difficulties of how you will achieve the results. When you plan a vacation you first decide where you want to go, then you sort out the logistics of how to get there and what to do along the way.

Step 4: Build a business case
Now that you know where you are going, what is it worth to get there? The business case answers the question “why do we want to have a reliability program?” It is not because we want to be top notch or be recognized at the next reliability conference. We want to make more money; that is why we are in business.

Fortunately there are very few endeavors that have a more compelling financial business case than a reliability-based maintenance management approach. And the homework you have done in Steps 2 and 3 make the calculation relatively simple. Consider the following examples:

• A 5 percent increase in Availability = a 5 percent increase in revenue for a continuous process plant that can sell all that it makes. A plant that produces $200 million per year generates another $10 million in revenue.

Reducing Overtime from 20 percent to 10 percent moves 10 percent of your labor from overtime rates to straight time rates. If your overtime multiplier is 1.5 and you have a $15 million labor budget you move $500,000 to the bottom line.

• Increasing your Planned Work from 50 percent to 80 percent moves 30 percent of your corrective work from unplanned to planned. Since a planned job costs 2/3 less, you save 20 percent overall. So for a corrective maintenance budget of $10 million you move $2 million to the bottom line.

Now when you are presenting your plans to the VPs from corporate and they ask “why do we need to do this reliability thing?” you can answer “because it will add $10 million to top line revenue and $2.5 million to bottom line profits.” Now you have their interest.

Building a compelling business case is often overlooked and underemphasized by technical experts in the reliability field. But executives are not persuaded by cool technology, world-class best practices, and the latest buzzwords. Even if they understand it and find it interesting, they will not act on it. So the function of the business case is to first educate the executives about the business value of reliability and then to explain the details of how you will roll out the program and how much it will cost. It is also very helpful to get your accounting folks involved in crunching the numbers to avoid credibility issues. Fig. 1 illustrates a typical business case for a small to mid-sized plant ($10 million-$20 million annual maintenance budget).

Step 5: Conduct a pilot program
Now you have gotten buy-in (or at least interest) at all levels of the organization, so where do you begin? The answer is to conduct some kind of pilot program. The pilot serves the following critical functions:

• Reduce initial investment. The pilot may cost only 10 percent of the full program, so you are far more likely to gain budget approval. And a mini-business case for a good pilot can easily show good returns in a short time period.

• Prove the business case. Even the best business case, completed with blessing from the accounting department, will have assumptions. The pilot serves to validate the assumptions and demonstrate the financial benefits.

• Test lab. You are attempting something new. So you want to be able to tweak things and figure out what works and does not work without the pressure and scrutiny of a huge project.

• Solidify buy-in. No matter how much preaching and planning you have done, many in the organization are going to be from Missouri. They need the “show me” of a pilot to get onboard for full rollout.

Selecting your pilot project is critical. Ideally, you want to identify a small but operationally significant portion of the plant and apply all of the new practices in that area. Make sure the project is small enough to initiate in 1-3 months and show significant results in 3-6 months.

Establish a method of tracking impact from day one. Document little successes and convert them to dollars using an accepted method like a balanced scorecard. Compile these into a success story and get accounting to bless the financial calculations.

Now you have got the buy-in, the confidence, and know-how to move forward with a plant-wide reliability program. And, more importantly, you have the proof you need to gain executive level funding approval.

Jay West is currently technology development manager for the Reliability division of BE&K, an engineering, construction, and maintenance company, 2000 International Park Dr., Birmingham, AL 35243; (205) 972-6000; e-mail ; Internet

BASIC LIST OF MAINTENANCE AND RELIABILITY PERFORMANCE METRICS

Metric

Top Notch Value

Availability: the portion of time that a plant or major system is available for producing output of the appropriate quality and quantity

95-99 percent

Percent Failure Analysis: the portion of equipment downtime events that undergo a thorough analysis of failure modes, effects, and root causes

85-100 percent

Percent Planned Work: the portion of corrective maintenance work hours that are planned and scheduled in advance (not unplanned breakdowns)

85-95 percent

Percent Overtime: the portion of maintenance work hours that are performed at an overtime rate

5-8 percent

Relative Maintenance Cost: maintenance spending as a percentage of asset replacement value of the plant being maintained

1.5-2.5 percent

Technician Productivity: the percent of work hours spent on productive activities vs nonproductive (rework, waiting for parts or tools, etc.)

70-85 percent

Percent Rework: the portion of maintenance work that has to be redone due to poor installation, shoddy workmanship, or incorrect diagnosis

2-5 percent

 

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 0505bekfig1

Fig. 1. Typical business case for a small to mid-sized plant ($10 million-$20 million annual maintenance budget).

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