CASE STUDY - HOW DID WE DO IT !

200 HP Multiple Compressors to Less Than 100 HP Saves $70,000 Annually!

Compressed Air Performance Specialists (CAPS Inc.) located in Calgary, Alberta (Canada) often hears the question “how did you do it” posed after yet another successful compressed air project has been completed for our client.  The most recent compressed air project the question is referring to is our reducing a 200 HP multi compressor system down to a single 100 HP VSD air compressor utilizing 75 HP of compressor energy (kWh) for $70,000 annual energy utility savings.  Many earlier compressed air system projects performed by Don Dyck President of CAPS Inc. (Calgary) are also enjoying similar successes! 

The end user client is a worldwide organization with a local Calgary facility producing frozen food products to various large retailers throughout Canada.  Having previously completed successful compressed air projects with an individual now involved within a management role to this local Calgary facility, in the late summer of 2013 the facility contacted CAPS Inc. to again perform our compressed air performance evaluation (CAPE) to their compressed air system. 

A comprehensive on-site CAPE was performed followed by a detailed 50 (+) page final report to the facility in October 2013.  In-depth discussions followed regarding the extensive CAPE report’s findings inclusive of supporting performance data/analysis tables, graphs and drawings, concluding with extensive recommendations and an initial capital equipment budget estimate.  The CAPE final report estimated the compressed air system annual energy (kWh) savings opportunities available to the facility versus the existing systems annual operational costs.  From this point, the Calgary facility obtained capital equipment/project funding approval and the beginning of a very successful project began for the facility to their compressed air system and annual energy savings opportunity.

For this project to be successful, CAPS Inc. can wholeheartedly acknowledge that the facility management individuals involved to this project where indeed on-board and supportive.  With their unwavering support, the end results to-date have far exceed the baseline estimates initially provided while greater energy savings opportunities are being continually pursued and achieved. 

The start point included an existing system consisted of three (3) individual air cooled oil flooded base mounted/enclosed rotary screw air compressors with dual refrigeration air dryers and limited in-line air filtration units aft of the dryers.  This was followed by a singular 200 gallon remote air receiver prior to delivering compressed air to a primary 4 inch main plant air header (loop) system.  The production floor sub piping systems was generally undersized and/or had lengthy linear service distances with additional issues associated such as high delta P service connections and/or air management devices for individual production equipment and/or areas.

The compressed air system operated 24 X 7 with two of the three air compressors running continually, while one of the air compressors (75 HP) ran near constant. Individual air compressors consisted of a 100 HP VSD, 75 HP and 25 HP (tank mounted) rotary screw compressor configuration collectively totaling 200 HP nameplate connected.

Operating mode and operating pressure/set points where set/adjusted in such a manner as two of the three compressors would run constant, and the remaining 75 HP compressor would auto stop/start as required via system low air pressure set point.  However this auto stop/start capability was generally manually overridden to ensure and maintain a final discharge air pressure to the 4 inch air header (loop) of 116.0 PSIG during frequent production air surge demand events to the production floor.

The existing three air compressors consumed an annual 996,000 (+) kWh of energy at an energy utility cost of $88,000.00 (+)/yr excluding the energy consumption attributed to the dual refrigeration compressed air dryers.  General day to day compressed air system operational performance issues encountered by the facility where frequent low plant air pressure alarm events, frequent high compressed air production demand surge events, high downstream compressor oil/condensate contamination downstream to the plant piping system and production equipment.  Additional general issues included utility/compressor room seasonal high ambient temperatures, and high temp operating conditions to individual air compressors.  Hence normal operational practice was to have all three (3) individual air compressors totaling 200 HP connected running.  Finally no reliable compressed air system performance verification capability excluding the low air pressure alarm device was present to the existing compressed air system.

During the extensive on-site period CAPS Inc. completed the CAPE including our primary elements of investigation, testing, measurement/logging and data analysis including but not limited to the following;

Installing accurate meter/data logging systems at strategic locations, which simultaneously logged in real time the downstream compressed air demand (CFM), compressed air pressure/temperature, and the compressor room ambient temperature and Rh%.

Installing individual power meters/loggers to each individual air compressors electrical “load” side ensuring all demand (kW) and power measurements included both the air end/exhaust cooling 3-phase drive motors.

Utilizing our highly accurate multi orifice ACFM flow measurement device to each air compressor’s package discharge air port, CAPS Inc. baseline performance tested and measured each individual compressors ACFM capacity output at baseline 100.0 PSIG, site altitude and temperatures.  Simultaneously during these individual ACFM capacity tests the measurement/performance data logging of the 3 phase voltage, current, power factor/quality and individual/total 3 phase demand (kW) to each compressor was performed.  During each of these ACFM @ 100.0 PSIG full load performance test periods to each air compressor, CAPS Inc. also conducted further testing at load/unload/modulating conditions; varying ACFM/PSIG demands and varying ambient inlet compression air/cooling air temperatures.

Now having very accurate individual compressor performance profiles at virtually every operational variable available at the CAPE period (summer), the extensive investigation, observation and overall system performance profiling began with simultaneous data measurement and logging to all key areas and the entire downstream compressed air system.  This lengthy period also included extensive first hand production practices/shift period observations of both production and production equipment/production areas and events, and specific items of investigation requiring further testing and/or concern.

The completion of the full CAPE and final report analysis illustrated the following supported performance testing and data profile findings and shall be generally outlined as follows;

The existing three compressors collectively delivered 801.2 ACFM @ 100.0 PSIG full load @ 70°F baseline discharge air temp @ 172.0 kW demand “load side” equaling 226.3 HP.  Normally the 100 and 25 HP compressors running would deliver 530.8 ACFM @ 100.0 PSIG full load @ 70°F baseline discharge air temp @ 116.3 kW demand (151.6 HP).  The remaining 75 HP compressor delivered 270.4 ACFM @ 100.0 PSIG full load @ 70°F baseline discharge air temp @ 55.7 kW demand (74.7 HP).  It is important to note as well the 100 VSD and 75 HP compressors each had 3 HP cooling exhaust fan drive motor while the 25 HP was a direct drive configuration.  It was very clear after the measured demand (kW) at full load ACFM testing the 100 HP VSD had a much lower performance efficiency kW (HP) per ACFM performance capacity.  To clarify this, the 100 HP VSD tested 127.0 HP (94.7 kW) @ 3.5 ACFM/HP measured @ full load @ 100 PSIG.  Performance testing for the 75/25 HP compressors confirmed the following 3.6 ACFM/HP/3.7 ACFM/HP performance values respectively.  The compressor (s) where set/operated to maintain 116.0 PSIG downstream plant air pressure, after the refrigeration air dryers/filtration assemblies delta P losses. 

Average 24 hr/day weekly production air demand was 438.2 ACFM @ 100 PSIG with frequent plant air production demand (surge) events being an average 650.0 ACFM with 700.0 ACFM maximum peak recorded while cause and effect brought the 75 HP air compressor on-line to assist during all surge events experienced.  Weekend periods had partial production and non-production hours with and/or without sanitation air demands being measured ranging from 150.0 to 275.0 ACFM.  Further performance testing/profiling verified the air system overall air leaks equaled 155.5 to 175.4 ACFM inclusive to production equipment, air lines, fittings, valves, tubing/fittings, hose/fittings, air control/treatment devices and other unspecified.

Ancillary ACFM demand performance testing to four individual ancillary devices and/or systems verified a range of 84.2 - 116.5 ACFM constant demand.  Six additional individual ancillary devices and/or systems collectively tested and measured a 189.1 – 266.9 ACFM intermittent demand range contingent on the number of ancillary devices and/or systems being utilized both during production and non-production periods.  Sanitation air demand volume would fluctuate contingent on the period of completion and would normally be in the range of 84.6 ACFM or greater.  CAPS Inc. defines ancillary air demand as follows; “Compressed air volume/demand (CFM) that is not directly associated to manufacturing the product/service, but is used to overcome a production process, function or equipment design deficiency”.

When reviewing the above air leak and ancillary ACFM demand values important clarifications must be indicated to fully understand the relevant factors to the facilities overall compressed air demand (kW) and energy (kWh) consumption.  The compressed air leak ACFM was indeed an accurate tested and measured value to the facilities compressed air demand profile for both production and non-production periods.  The ancillary compressed air ACFM values noted reflected both the low/high ACFM potential of ancillary demand.  Examples of potentials include two production lines having a blow bar and dual blow guns being utilized to blow off finished product debris from product trays.  The blow bar utilized 61.6 ACFM during production, and the blow guns would utilize 30.0 (1 blow gun) to a maximum 60.0 (2 blow guns) ACFM contingent on the individual operator at that time of production (min 90 to max 120 ACFM).  Additional examples included a dust collection system whereby during production and/or non-production periods requiring its filter purge cycles to operate, the cycles consumed 19.9 ACFM every 20 seconds (24 X 7).  Electrical cabinet cooling guns also contributed to ancillary ACFM demand with four units in total and a constant ACFM demand of 23.2 for two units, and 55.5 ACFM total for all four cooling guns operating.

As I’m certain the magnitude of opportunities for this facility are now becoming clear, the CAPE final report detailed specific recommendations including PSIG/ ACFM reduction target values for the facilities management personnel’s consideration.  In order to illustrate the general opportunities available to which the facility pursued, the following outlines briefly the progression of recommendations implemented to date;

  1. Compressor room air system, including installing/upgrading:

    1. Dual 1060 gallon vertical air receivers (wet air receivers-twinned).

    2. Appropriately sized in-line compressed air filtration assemblies (Boge).

    3. Singe appropriated sized refrigeration air dryer (Boge).

    4. In-line compressed air flow pressure regulator (ConservAir).

    5. New 63 mm compressed air piping throughout (Transair).

    6. Utilizing both no air loss and timed solenoid condensate auto drains.

    7. Installing SCFM flow and data logging systems (CDI Meters).

  2. Compressors operating temperatures/compressor room ambient temperature:

    1. Upgraded and improved the 100 and 75 HP compressors fresh air inlet/hot air exhaust ducting systems.  The facility envelope did not need any additional heating capacity.

    2. Inclusive of installing individual fresh air inlet/hot exhaust/warm air mixing louvers with electric actuators for open/close and/or modulating operation to the 100 and 75 HP compressors.  Ensuring 513,000 (+/-) BTU’s/hr was ejected outside and 114,000 BTU’s/hr was eliminated (25 HP compressor disconnected). 

  3. Individual compressors:

    1. Shut off and disconnected the tank mounted 25 HP compressor.

    2. Serviced and installed/retrofitted (as required) new control devices to 75 HP air compressor complete with operating mode “auto start/stop” and operating pressure set point adjustments.

    3. Serviced and adjusted operating mode/pressure set points to 100 HP VSD.

  4. Located new ConservAir intermediate pressure/flow controller installation aft of refrigeration dryer, prior to main 4 inch plant air header (loop):

    1. Operating pressure set to 105.0 PSIG for main 4 inch plant air header (loop)

  5. Utilized 63 mm Transair blue pipe throughout with final connect to existing main 4 inch plant air header (loop).

  6. Installed CDI flow meters with LED displays and USB programmable data logging devices.

  7. Installed several high quality pressure gauges at several strategic locations before/after to visually verify both overall system air pressure and delta P’s to all compressor room air treatment equipment.  Gauge installations also included the 100 and 75 HP compressors discharge air outlet pipe connection for actual discharge pipe to compressor panel PSIG comparisons.

  8. Installed high quality compressed air approach temperature gauge prior to refrigeration air dryer for visual reference of compressed air approach temperature.

  9. Installed at all locations to equipment noted above including air pressure/temperature gauges manual full port ball valve by-pass/isolation systems.

  10. Future (TBD) – compressor (s) power meter/energy logging/data management system.

  11. Facility personnel minimized significant compressed air surge demand events from specific production floor product line devices.

  12. Began air leak minimization program, with to date results showing an approx. 75 ACFM (+/-) reduction while program is on-going.

  13. Began installation at critical locations upgrading of existing undersized schedule 40 black sub air service pipe to Transair blue 63, 40 and 25 mm pipe as deemed appropriate.

  14. Utilized and relocated existing original 200 gallon air receiver to dust collection system.

  15. Installed new remote 120 gallon vertical air receiver common to dual product packaging lines.

  16. Installed at strategic locations additional high flow/low delta P point of use and/or production area compressed air filtration assemblies with program on-going.               

  17. Retrofitted and/or reconfigured several point of use and/or production areas compressed air control systems improving compressed air flow while reducing operating pressures and delta P’s throughout with program on-going.

  18. Replaced, upgraded and improved several production areas where existing service line tubing was undersized and/or aged with larger diameter tubing and fittings with program on-going. 

  19. Began reductions and/or eliminating ancillary compressed air demands as described earlier.  A few examples include the redesign and installation of new compressed air product tray debris blow off nozzle systems.  Final ACFM air consumption total for both of the two new systems is 28 ACFM @ minimum 62 to maximum 92 ACFM reductions achieved.  Additional reductions included the shut off of 3 electrical cabinet cooling guns for 35 (+) ACFM, and minimizing dust collector filter cleaning cycles when not needed for a 19.9 ACFM reduction opportunity with ancillary air demand reduction program on-going.

  20. Throughout all of the above mentioned upgrades and/or retrofits/repairs to date the end goal achieved were (to date) significant air leak and ancillary ACFM demand reductions while reducing key locations operating pressures and/or significantly reducing eliminating areas having high delta P issues.

As briefly outlined numerous areas of improvement to the plant production floor compressed air system has been achieved and continues to-date.  The completion of the improvements has continually marked a reduction to the varying weekly production compressed air demand volumes (ACFM) now required.  In addition a significant reduction during non-production periods in compressed air demand volume (ACFM) is also being experienced, while comfortably operating at a primary plant air header pressure of 105.0 PSIG for both production and non-production periods.  To simplify an illustration for every 20.0 ACFM/100.0 PSIG in production/non-production compressed air demand reduction achieved, an energy savings of $3,000 (+) annually @ $0.08/kWh is achieved, and jumps to $3,700 (+) annually @ $0.10/kWh.

The dramatic performance and annual energy consumption improvements starting at the compressor room with only the 100 HP VSD compressor being required and operating in a load/unload mode, dual 1060 gallon air receivers, main compressed air piping, refrigeration air dryer/filtration, intermediate pressure/flow controller and the room ambient temp including the compressor cooling air ducting system has been significant.  Couple the compressor room with the plant production floor work already completed if you can envision the original compressed air system with a total connected 200 HP for 3 compressors, now only using a single 100 HP VSD compressor operating at load/unload mode utilizing approx. average 75 HP (-) during weekday production and less than 30 HP for weekend non-production periods the magnitude of success for this facility to-date is apparent. 

CAPS Inc. issued the original CAPE final report in October 2013 and identified the following conservative energy savings opportunity for the facility based on $0.08/kWh at the time of the CAPE report and as follows:

“The following briefly summarizes this 2013 CAPE final report and the overall estimated operational energy savings opportunities to the facility (Section 20.0) being an estimated 667,000 (+) kWh annual reduction for an estimated annual $54 – 61,000 (+) $/kWh energy operating savings @ $0.08/kWh.”

Delivery of capital equipment occurred in late June 2014 with the comprehensive compressed air project commencing shortly thereafter and starting at the compressor room proper.  Within a 7 month period the compressors and compressor room system was completed with several plant production floor projects underway as well.  Early 2015 focused on several point of use areas to the production floor and the positive energy savings results continue to significantly increase from the original conservative savings estimates determined in October 2013.  In co-operation with facility management and personnel, CAPS Inc. to-date has continued completing plant production floor projects which has the compressed air systems annual energy savings opportunity potentially exceeding $70,000 (+) $/kWh versus the conservative October 2013 estimated energy savings range.  As CAPS Inc. progresses to the final completion of this overall project, even further compressed air system energy savings may be obtained where in co-operation with the facility recent investigations into utilizing alternate methods and/or retrofitting of operation for key equipment functions such as palliating may be available.

Once again we will stress the importance were a facility/organization has highly motivated management and personnel such as this facility, the annual energy savings opportunities to the compressed air system can be very dramatic while also dramatically reducing downtime and significantly improving throughput.  For capital equipment and new compressed air line supply/installation the facility and CAPS Inc. utilized a local compressed air capital equipment supplier/service/installation firm namely Central Air Equipment (Calgary, AB Canada).  Their involvement to the compressed air project was also crucial in the to-date success already achieved.   

CAPS Inc. goal is always the ultimate benefactor being the facility and the annual energy savings now being on-going with further success to their facilities near future.  If you wish further discussion and/or to inquire as to our services please feel free to contact myself (Don Dyck) via email caps.inc@shaw.ca and see how we can afford ably help you. 

While reviewing our web site take a look at our Southern Alberta Institute of Technology (SAIT Calgary AB Canada) and CAPS Inc. one of kind compressed air workshops utilizing the CAPS Inc. designed fully functioning CALES system.  The CALES platform simulates in real time virtually any compressed air performance variable you may be experiencing while visually illustrating the performance data measurements in real time showing you exactly how compressed air variables affect demand (kW) and annual energy (kWh).