Alcom Reynosa

Compressed air flow audit Compressor Rooms 1 and 2

Written By: Shane Egner

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Executive Summary

The purpose of this report is to convey the results of the compressed air flow study performed in Compressor Rooms one and two along with the results of point of use flow in MD1 Alpine Assembly Area and moulding. The compressed air system consists of two compressor rooms with one room containing three 50 HP air compressors and one 125 HP and the other room contains four 50 HP and one 100 HP compressor for a total installed HP capacity of 575 HP and over 2,300 SCFM.

Alcom Compressor Rooms 1 and 2

 

 

Flow (SCFM)

 

 

Pressure (PSIG)

 

% Capacity

 

Min

 

Max

 

Average

Min

 

Max

Average

Min

Max

Average

Compressor Room 1 (8Sept14)

601.76

 

861.33

 

778.44

98.19

 

109.36

103.17

43%

62%

56%

Compressor Room 2 (5Sept14)

29.95

 

393.28

 

266.04

94.13

 

110.52

104.41

3%

36%

24%

Combined (10Sept14)

1076.19

 

1446.27

 

1256.69

96.74

 

106.31

101.69

47%

63%

55%

The chart below is the summary of the point of use flow measurements for one production cell in MD1 Alpine Assembly and one moulding machine (A-34)

Production Area Point of Use

 

 

Flow (SCFM)

 

Pressure (PSIG)

 

Min

Max

Average

Min

Max

Average

MD1 Alpine Assembly

0.36

22.9

8.42

85.28

108.49

100.29

Moulding Machine A-34

0

16.62

5.15

85.43

104.86

97.19

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Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

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 uncontrolled demand in production can cost an incredible amount of money and also reduce the redundancy of facility systems.

2: Methodology

Compressed air flow meter (inline):

One of the compressed air flow meters used for this study is a one- inch inline flow meter (VPFlowScope® In-line) designed for portable point of use compressed air flow, temperature, and pressure measurements. The meter was installed between the supply compressed air lines and the lines feeding air to the production cells. Flow and pressure were recorded once every 5 seconds and temperature was recorded one time every 10 seconds.

Compressed air flow meter (insertion):

One of the compressed air flow meters used for this study is an insertion type inline flow meter (VPFlowScope®) designed for portable and permanent compressed air flow, temperature, and pressure measurements. The meter was installed in the main header between the compressor room and the compressed air distribution system. Flow and pressure were recorded once every 5 seconds and temperature was recorded one time every 10 seconds.

Data Loggers:

The measurements for flow, and pressure were recorded using a Onset UX120-006M data logger. The data is read and graphed through Onset’s software called HOBOware.

3

Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Compressor Room 1:

Compressor Room 1 consists of one 100 HP rotary screw air compressor and four 50 HP rotary screw air compressors. During normal daytime production Compressor Room 1 has 4 compressors running: three 50 HP and one 100 HP. The configuration of equipment in Compressor Room 1 can be seen in the schematic below:

Compressor Room 1 is piped in the best method with a “wet tank”,“dry tank”, and dryers installed in parallel with each dryer having the capacity of the system. The graph of flow and pressure is below. One interesting note about the flow and pressure: in two situations where the flow decreases the pressure decreases for the same period of time which is due to a compressor reaching its pressure setpoint and going into a standby mode until the pressure falls to the point where it needs to load, but when the compressor unloads just after 3:00 PM the pressure continues to rise. This can be due to two things: production reduced drastically for that period of time and demand reduced, or (the more likely situation) a compressor in compressor room 2 loaded up and caused a compressor in Compressor Room 1 to unload while plant pressure still increased. The control settings of the compressors will be discussed later in the report.

4

Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Compressor Room 2:

Compressor Room 2 consists of 4 rotary screw air compressors; one 125 HP two stage compressor and three 50 HP compressors. During normal production either three 50 HP compressors or the one 125 HP compressor operate to maintain pressure in the facility. The configuration of equipment in Compressor Room 2 can be seen below:

Compressor Room 2 is piped very similarly to Compressor Room 1 with a “wet tank”, “dry tank”, and dryers installed in parallel. The graph of flow and pressure of Compressor Room 2 is shown below. One interesting note about the flow from Compressor Room 2 is that there were three 50 HP compressors operating to maintain pressure. The flow from three 50 HP compressors should be in the 600 CFM range. What was found is that one of the compressors was operating, but not pumping air due to a faulty control valve.

5

Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

The graph below is the graph of Compressor Room 2 flow and pressure with the pressure from the moulding area superimposed over the data. It is interesting to notice that the pressure in the moulding area follows the pressure in Compressor Room 2 with an average offset of around 7 PSI. This pressure offset represents around 3.5% of running compressor power and can be eliminated by finding and eliminating the source of pressure drop.

Compressor Rooms 1 and 2 Combined:

The graph below is a representation of flow and pressure from Compressor Room 1 and Compressor Room 2 superimposed over each other. The data shows that in some instances Compressor Room 1 and Compressor Room 2 are actually fighting each other.

6

Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

The graph below is an example of how the control setpoints can be modified to help the system be more efficient. The first situation where flow in Compressor Room 2 increases and flow in Compressor Room 1 decreases (approximately 9:50 AM) is caused by the unload setpoint being reached in one compressor in Compressor Room 1. The increase in flow from Compressor Room 2 is only from compressed air storage. The second situation is due to the 125 HP compressor turning on and loading up. This caused a 50 HP compressor in compressor room 1 to unload until the 125 reached it’s unload setpoint.

The graph below is a representation of the worst situation in a dual entry point compressed air system. When the compressors operate in this manner they will never be able to shut down in standby mode.

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Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Control Setpoints:

The control setpoints for both compressor rooms are shown here graphically. One major problem with the way the controls are set up in this situation is that all compressors but one are set to unload at the same pressure. Fortunately, the pressure readouts on the machine do not match. The transducers probably need to be calibrated.

The first part of a good control scheme is determining which compressor room will be the “base load” compressor room. For the purposes of this report we will make Compressor Room 2 the base load and Compressor Room 1 will make up the extra flow to maintain plant pressure.

In this configuration the 125 HP 2 stage compressor will be the base loaded compressor and should only cycle when the flow of the plant is below 600 CFM. When the flow of the plant is between 600 and 800 Compressor 8 will cycle to maintain pressure and so forth until the flow is above the capacity of Compressor Room 2 (approximately 1200 CFM). If demand flow of the plant is above the demand of Compressor Room 2 then compressor 13 will come online and be the trim compressor. C13 is the 100 HP compressor. If the demand of the plant becomes higher than Compressor Room 2 and C13 can provide then C3 will turn on and become the trim compressor. When the demand of the plant reduces the operation of the compressors will reverse.

Placing the compressed air system in this control configuration will require that all pressure transducers be calibrated (performed onsite by technician). The

data shows that there is approximately a 4 PSI pressure difference between Compressor Room 2 and Compressor Room 1. The first time this control scheme is implemented pressure should be monitored to ensure the pressure differential does not cause a problem.

The other option is to install a system controller. The controller has built in control schemes and is designed to cycle the compressors to maintain one plant pressure.

Plant Pressure Drop:

Depending on the time of day and compressed air demand from production there is a pressure drop between 6 and 9 PSI from Compressor Room 2 to the moulding area. This pressure drop could be due to the extra clean up equipment installed on the mezzanine in the moulding area. This pressure drop results in the compressors operating at an elevated pressure. This elevated pressure presents a savings opportunity between 3% and 4.5% of compressor power cost.

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Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Moulding:

The point of use flow and pressure meter was installed in moulding machine A-34 to determine the compressed air demand from one moulding machine. The graph of the data is below:

MD1 Alpine Assembly:

The point of use flow meter was installed in one production cell in the MD1 Alpine Assembly area. The graph of the data is below.

Drain Valves:

It was noticed during the audit that most of the drain valves in the facility are the timed electric solenoid type. These drain valves have an inexpensive initial cost and do work when set up properly. There are a couple of problems with the electric drain valves. The first (and biggest) problem is there is no way to determine if the valve is working. While pressing the test button will result in a “click” that does not mean the valve is actually releasing condensate. The second problem is that the amount of condensate generated by the compressed air system varies with capacity, temperature, and pressure. For the drain valve timer to be set for the largest possible amount of condensate it will need to stay open and discharge air for all times other than worst case.

Float type no loss drains solve this problem. They have a clear plexiglass tube for easy diagnosis of drain valve problems and they only discharge condensate when they open. The drain valves can be installed in a rack and labelled for which piece of equipment they are installed. This will allow technicians to look at all drain valves in one location.

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Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

Recommendations:

1.Find and eliminate source of pressure drop from compressor rooms to production areas. Reduction in compressor output pressure of 2 PSI results in 1% reduction in power.

2.Install master system controller or change control scheme to base load/trim station.

3.Replace electric drain valves with no loss drains.

4.Install monitoring system to ensure compressed air system is always operating at its peak efficiency.

5.Replace two 50 HP compressors with 100 HP variable speed drive compressor installed in MD3.

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Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

11

Alcom Reynosa compressed air system Flow Study

Egnergy

3400 N McColl Suite F11

Mcallen, TX 78501

210-560-6568

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Alcom Reynosa compressed air system Flow Study