Kohler

Compressed air energy audit

Written By: Shane Egner

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Executive Summary

The purpose of this report is to convey the results of the compressed air energy study performed at Kohler’s Reynosa Mexico facility from Sunday August 10th through Friday August 15th of 2014.

The compressed air system is operating at 78% efficiency with a potential for energy savings of over $33,000 annually. This cost reduction can be achieved with a return on investment of less than two years.

 

 

Existing

 

New

 

 

System

 

System

Annual KWH

681,374

 

410,234

Annual Cost (USD)

$85,172

 

$51,279

@$.125/KWH

 

 

 

 

 

 

 

System Efficiency

 

78%

 

98%

Average Flow (CFM)

 

325

 

288

Average Power (HP)

 

104

 

72

 

 

 

 

 

 

 

Equipment Cost

 

 

New System

 

 

1100 CFM High Efficiency Filter

 

$5,900.00

 

 

2 X 100 HP VFD Drives

 

 

$20,446.40

 

 

5 No Loss Drain Valves

 

 

$4,000.00

 

 

Egnergy Efficiency Meter

 

 

 

 

 

 

 

(includes control for 6 isolation

 

$19,661.00

 

 

 

 

 

valves and valves)

 

 

 

 

 

 

 

Total

 

 

$50,007.40

 

 

Energy Savings (annual)

 

 

$33,892.54

 

 

Return On Investment (Years)

 

 

1.5

 

 

2

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

1:Introduction

Cost reduction is an essential part of a manufacturing facilities sustainability and continued success. This report shows in detail how the cost savings, return on investment calculations and data collection were performed.

**Power cost calculations are base on an electrical cost of $0.125/KWhr**

2: Methodology

Compressed air flow meter:

The compressed air flow in SCFM (Standard Cubic Feet Per Minute) was measured using a CDI Meters 5400-30S flow meter (data sheet in figure 1). The flow meter was installed in the pipe between the compressed air system and the compressed air distribution system (before the flow control valve). This meter uses a loop powered 4- 20 milliamp signal to transmit compressed air flow to the data logger. The flow is recorded one time per second in units of SCFM.

Pressure Transducer:

The compressed air pressure was measured using 4 Pressure transducers. One installed at the inlet of the distribution system, one installed in the tank, and two installed in the production areas (one at Cut to length and one at the channel welder). The locations for measuring pressure in the plant were determined by plant personnel due to the channel welder being most sensitive to pressure fluctuations and the cut to length area being the furthest distance from the compressor room. The pressure transducers used have a range of 0 – 200 PSIG with a corresponding meter output from either 0 – 5 VDC or 4 – 20 mA. The pressure transducer is connected to the logger using a DC power supply for excitation voltage. Pressure is recorded every 1 second in units of PSIG.

3

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Compressor Power:

Compressor power was measured using a Veris Industries H8042-0300-2 power transducer. The power transducer monitors the incoming power of the compressor in KW and was recorded one time per second. The power transducer measures voltage and current and calculates power to be output to the data logger via a 4 – 20 mA signal. Data sheets for the H8042-0300-2 can be found in figure 3.

Data Loggers:

The measurements for flow, pressure, and compressor power were recorded one time per second using two Onset UX120-006M and one LogicBeach IL80. The data is read and graphed through Onset’s software called HOBOware.

3: Results

Compressed air consumption:

Sunday:

The graph below is a representation of compressed air flow and the power to generate the flow for Sunday 8/10 through Monday 8/11 at 6:00 AM (prior to production starting). The average flow of the system was 258 SCFM and the average power was 93.91 HP. The compressed air usage during this 12-hour period cost approximately $142. Assuming this usage was constant for 24 hours every Sunday the average annual cost is $14,600.

4

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Compressed air consumption:

Monday - Saturday:

The graphs below show the parameters recorded in the compressor room: Power, Flow, Pressure, and % Efficiency. The average power for Monday – Saturday was found to be 106 HP with an average flow of 336 SCFM. The maximum flow of the system was 492 SCFM, which is very close to the capacity of one compressor. During this situation, the compressor is actually operating at greater than 100% efficiency. This is due to the motor operating at 100% power, but not maximum pressure. This condition is known in the compressed air industry as drawdown. The maximum flow event did not occur for an extended period of time, but could cause problems in the future. The annual average cost to run the compressor Monday – Saturday is calculated to be $74,200.

5

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

The graph below shows 12 hours of system operation. The graph shows there are periods of high demand within the system. These high demand periods usually last between one to two hours. In this case it occurs around 11 AM.

Compressed air system efficiency:

The compressed air system efficiency was calculated by comparing the rated CFM/HP ratio of the operating compressor to the actual CFM/HP ratio of the compressed air system. The nameplate flow rating for this compressor is 495 CFM with a power rating of 122 HP (see CAGI compressor rating in Figure 4). The data collected shows an average flow rating of 336 CFM with an average power of 106 HP. This gives us an ideal ratio of 4.1 CFM/HP and an actual ratio of 3.2 CFM/HP. The ratio of actual to ideal gives system efficiency, which is 78%.

Lower plant pressure: One opportunity for savings for Kohler Reynosa is to reduce the pressure in the distribution system to the minimum possible without affecting production. The minimum plant pressure during the study was found to be 81 PSI at the Channel Welder and 80 PSI at the Cut To Length section of the plant. It is reasonable to assume that 80 PSI is a good starting point for plant pressure, but it may be able to be lowered beyond that. This will reduce the compressed air flow of the plant by around 5% because there will be less force to push the air through the leaks.

6

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Online/offline curve:

The curve above is a representation of variable speed drive and online/offline controlled compressor efficiency. The curve is used by first calculating the ratio of compressed air storage to maximum compressed air flow. This ratio is used to determine which line the system efficiency falls on. The capacity of compressed air storage for Kohler is 1060 gallons while the compressor capacity is 495 CFM. This gives a gal/CFM ratio of approximately two. It is fairly obvious from the graph above that a ratio for gal/CFM of two is less than desirable. The red line on the graph represents the ratio of flow to capacity with a variable speed drive. The ratio is 1:1 from 50% capacity to 100% capacity and is the most efficient way to operate an air compressor.

7

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

System Drawings

Existing system:

Proposed system :

8

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Pressure differential: Another parameter that was examined was the differential in pressure between the compressor room and the facility. This differential pressure is important because if it is large it can cause an inflated pressure at the compressor room to compensate for the pressure drop in the distribution system. The pressure differential at the Kohler Reynosa facility is around 9 PSID from the tank to the Cut To Length section of the plant. The addition of a flow control valve to separate supply from demand in the system and high efficiency low pressure drop filter will help to minimize this pressure drop.

The Channel Welder has too many filters and regulators in the piping prior to entering the machine. All filters but one should be removed to reduce pressure drop during machine operation.

Drain Valves:

The compressed air system has four electrically operated drain valves. Each of these drain valves represents a great opportunity for savings. The list below details the drain valves and how long each is open.

a.One on for 10 sec every 8 minutes = 75 seconds per hour

b.One on for 5 seconds every 15 minutes = 20 seconds open per hour

c.One on for 7 seconds every 45 minutes = 9.3 seconds open per hour

d.One on for 7 seconds every 5 minutes = 84 seconds open per hour

Each valve is effectively a 1/4” orifice which leaks 86 CFM at a pressure of 90 PSI. The valves are discharging air like an open 1/4” leak 188 seconds out of every hour. This equates to 458 hours per year. The compressed

9

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

air system is operating at 3.2 CFM/HP it is like a 27 HP compressor operating for 458 hours of the year. Replacing these drain valves with no loss drain valves will save Kohler around $1000 pear year.

4: Conclusions

The compressed air system in the Kohler Reynosa facility is operating at a moderate efficiency level. There is a potential for an increase in efficiency of 22% for a total annual savings of around $33,000.

5:Recommendations

1.Install VFD drives on existing compressors

2.Reduce compressed air demand on Sunday to a minimum level

3.Install no loss drain valves on all drain points of system

4.Install high efficiency mist eliminator filter

10

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

CDI 5400

FLOWMETER FOR COMPRESSED-AIR

SYSTEMS Rev. 2.0

Easy to install

No moving parts

Digital display

Milliamp and pulse outputs

No calibration or setup required

Complete flowmeter in one package

Optional RS-485 output for net- working

Housing rotates to suit vertical or horizontal installation

The CDI 5400 clamps onto a pipe, with two flow-sensing probes projecting into the pipe through 3/16-in. drilled holes. It seals directly to the pipe; no cutting or welding is required for installation. Because each flowmeter is made and calibrated for a specific size of pipe, the digital display indicates flow directly, with no setup or adjustment.

The meter measures flow by maintaining one probe warmer than the other. It calculates the mass velocity from the amount of heat required, and then calculates the flow on the basis of pipe area. The flow rate, in scfm, is shown on a large, four-digit display; a 4-20 mA output and a pulse output permit remote display, totalizing and data collection.

AVAILABLE SIZES

Nom

Calibrated

Model No. for

Model No. for

range b

Size a

Sch 40 Steel

Type L Copper

(scfm)

2 in.

4

- 400

5400-20S

5400-20Cc

2.5 in.

5

- 500

5400-25S

5400-25C

3 in.

12

- 1200

5400-30S

5400-30Cc

4 in.

20

- 2000

5400-40S

5400-40Cc

5 in.

20

- 2500

5400-50S

--

6 in.

50

- 5000

5400-60S

--

8 in.

100 - 6000

5400-80S

--

SPECIFICATIONS

Accuracy:

5 percent of reading plus one percent of full scale at air temperatures between 40 and 120 degrees Fahrenheit

Accuracy, extended range:

7 percent of reading from rated full scale to 150 percent of calibrated range, at air temperatures between 40 and 120 degrees Fahrenheit

Fluids:

Compressed air and nitrogen

Operating pressure:

200 psig maximum on Sch. 40 steel and on Type L copper below three inch; consult CDI for other materials and higher pressures.

Input power:

250 mA at 18 to 24 Vdc

Output resistance:

400 Ohms max.

Materials exposed to measured fluid:

Stainless steel, gold, thermal epoxy and Viton (seal)

Ring material:

Aluminum

(a)Meters are also available for several sizes of Aluminum pipe. For metering smaller pipe sizes, please see our Series 5200 flowmeters.

(b)Accuracy will be reduced when flow is outside of the specified range. Milliamp scale ranges differ.

(c)Flowmeters for 2”, 3, and 4” copper have smaller calibrated ranges.

Display:

Four-digit LED display

Response time:

One second to 63 percent of final value

US Patent 6,802,21

Figure 1

11

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Model G2 Pressure Transducer

Cable

Connection

Hirschmann

Connection

Metri-Pack

Connection

Flying Lead

Connection

LOOK FOR THIS

AGENCY MARK ON

OUR PRODUCTS

APPLICATONS

The G2 pressure transducer combines performance with value to meet the demanding needs of the original equip- ment manufacturer in applications found in:

Off-road Equipment

Construction Machinery

Performance Racing

Railroad/Transportation

Compressor Control

HVAC and Refrigeration

Agricultural Implements

Process Automation and Control

Hydraulic & Pneumatic Sensing

Pump Monitoring

FEATURES

1% Total Error Band Accuracy

Broad Temperature Capability

All-welded pressure construction

High EMI/RFI rating

Ranges 30 psi through 20,000 psi

IP 67 Ingress rating

Diagnostic rails

The Ashcroft® Type G2pressure transducer has been specifically designed with the high volume OEM in mind.

A ±1% Total Error Band accuracy is accom- plished by marrying a high performance ASIC to a very stable, field proven polysilicon thin film pressure sensor. The sensor is electron beam welded to a pressure fitting of stainless steel, which provides excellent overpressure capability and outstanding durability in the presence of shock and vibration.

The circuitry is held within an internal cage and housed in an enclosure of reinforced Nylon.

TOTAL ERROR BAND (TEB)

Error limits of all points (0-100% of range)

 

2.0%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.5%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

of span)

1.0%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.5%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.0%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Error

-0.5%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-1.0%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-1.5%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-2.0%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-60

-40

-20

0

20

40

60

80

100

120

140

 

 

Ambient Temperature (C)

 

 

 

Pos Error Limit

 

 

 

 

 

 

 

 

Neg Error Limit

 

All specifications are subject to change without notice.

 

All sales subject to standard terms and conditions.

BULLETIN G2

© 2013 Ashcroft Inc., Rev. 08/13

PERFORMANCE SPECIFICATIONS

Ref. Condition 21°C ±1°C (72°F ±2°F)

Accuracy:

Total Error Band includes combined effects of temper- ature, non-linearity (Terminal Point Method), hysteresis, non repeatabilty, zero offset and span setting errors

±1% of Span: From –20 to 85ºC (–4 to 185ºF)

±1.5% of Span: From –40 to –20ºC (–40 to –4ºF) ±1.5% of Span: From 85 to 125ºC (185 to 257ºF)

Note: Static accuracy ±0.25% of span BFSL (Best Fit Straight Line Method); includes non-linearity, hysteresis and non-repeatable effects at reference temperature 72°F (21°C)

Stability: Less than ±0.25% span/year Durability: Tested to 50 million cycles

ENVIRONMENTAL SPECIFICATIONS

Temperature:

 

 

Compensated

–40 to 125°C

(–40 to 257°F)

Operating

–40 to 125°C

(–40 to 257°F)

Storage

–40 to 125°C

(–40 to 257°F)

Humidity: 0 to 100% R.H., no effect

FUNCTIONAL SPECIFICATIONS

Select from over 25 pressure ranges starting at 30 psi and running through 20,000 psi gauge. Compound (vacuum & pressure) ranges are also available, see “To Order” on back.

Overpressure (F.S.):

Proof

Burst

750 psi & below

200%

F.S. 1000% F.S.

1500 psi

200%

F.S.

500% F.S.

3000 psi

200%

F.S.

500% F.S.

5000 psi

150%

F.S.

500% F.S.

7500 psi

120%

F.S.

500% F.S.

10,000 psi

120%

F.S.

240% F.S.

20,000 psi

120%

F.S.

240% F.S.

Vibration: Random vibration (20 g) over tempera- ture range (–40° to 125°C). Exceeds typical MIL. STD. requirements

Shock: 100gs, 6 ms

Drop Test: Withstands 1 meter on concrete 3 axis

Response Time: Less than 1 msec

Warm-up Time: Less than 500 msec typical Position Effect: Less than ±0.01% span, typical

ELECTRICAL SPECIFICATIONS

Output Signals Available:

Supply

 

 

Voltage Output

Excitation

Current

0-5 Vdc, 3 wire

9-36 Vdc

5mA

0-10 Vdc, 3 wire

14-36 Vdc

5mA

1-5 Vdc, 3 wire

9-36 Vdc

4mA

1-6 Vdc, 3 wire

9-36 Vdc

4mA

0.5-4.5Vdc, 3 wire

9-36Vdc

4mA

Ratiometric Output:

 

 

0.5-4.5 Vdc, 3 wire

5 Vdc ±0.5 Vdc

3.5mA

Current Output:

 

 

4-20mA, 2 wire

9-36 Vdc

 

Reverse Polarity & Miswired Protected: Yes Insulation Breakdown Voltage: 100 Vac

Insulation Resistance: Greater than 100 megohms at 100 Vdc

CE Marked: Per DoC

EMC Directive 2004/108/EC

IEC/EN 61326-1:Edition 1.0 Industrial

IEC/EN 61326-2-3:Edition 1.0 Annex BB Industrial PED Directive

Ashcroft Inc., 250 East Main Street, Stratford, CT 06614 USA Tel: 203-385-0648 • Fax: 203-385-0408

email: info@ashcroft.com • www.ashcroft.com

Figure 2

12

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Figure 3

13

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Figure 4

14

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

Vibration:

The graphs below represent the vibration on the air end and motor bearings in units of in/sec-PK. This measurement was taken as an extra for the report. Vibration in the air end and motor of both compressors reduces when the compressor is unloaded. The vibration of compressor number one is around 20% higher than the vibration in compressor number two.

These numbers are interesting, but not very useful. The vibration of the bearings would need to be trended over time to see how the bearings are wearing in the machine.

15

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

16

Kohler Reynosa compressed air system cost reduction

Egnergy

19718 Ranch Meadow

San Antonio, TX 78258

210-560-6568

17

Kohler Reynosa compressed air system cost reduction