Improvement actions

Introduction

CALMS compressed air optimization platform, has taken a whole new approach to improve the reliability, financials and sustainability of compressed air systems. The 5-step approach systematically identifies potential savings and leads steps by step towards energy and sustainability excellence with improvements opportunity cards.

Each of the steps contains specific actions that will be automatically identified and suggested to create a more energy-efficient system and reduce carbon footprint. The system as a whole is analysed and monitored. The steps towards continuous improvements.

Based on identified opportunities for improvements CALMS will create cards under each step.

Each improvement opportunity card will contain current situation and opportunity description with link to action in CALMS and link to detail explanation and identified impact on :

  • Reliability
  • Financial
  • Sustainability

Disclaimer: Final solution must be verified by CA expert.

Action cards list and description

Create system review

This is the first card when you add new system. Card will pop up under Assessment group. Until complete System review and system setup will be done System KPIs will not work.

The minimum requirements for System Review are at least one note or opportunity, complete System details page with CA cost and TCO and Setup, complete all answers on Efficiency and Reliability page and saved Potential savings.

Complete system review

System review is not completed, all pages must be filled completely.

Same as Create system review card.

Decrease system pressure

Before decreasing system pressure measure pressure across the factory and check for the lowest pressure. Best is to start with monitoring or audit.

Too low pressure can cause even more damage to the production.

Too high pressure will cause energy inefficient system.

Our recommendation is to operate compressed air for standard instrument air at system pressure 6-6.5 bar (90-95PSI) or lower. If air system piping does not support this kind of pressure we would suggest to develop a generic piping schematic diagram for use in conducting a thorough system assessment.

Install pressure drop indicators

Purpose of differential pressure monitoring devices in connection with monitoring will bring numerous benefits to regularly changing compressed air filter elements like:

  • High quality compressed air
  • Protection of adsorption (desiccant) dryer beds
  • Protection of downstream equipment, personnel and processes
  • Reduced operational costs
  • Increased productivity & profitability
  • Continued peace of mind

Differential pressure is a measurement of pressure loss in a compressed air system. To achieve a constant downstream pressure required to operate equipment and processes, an air compressor must often operate at a higher operating pressure and/or for longer periods to overcome the pressure losses.

Every 14.5 psi (1 bar) of differential pressure an air compressor (positive displacement type) must overcome is equal to approximately 7% increase in electrical consumption. So, while keeping differential pressure losses low is good practice, compressed air quality is the main reason for changing a filter element.

Cost of maintenance and replacement parts are insignificant compared to those associated with product spoilage should a filter element fail. What seems like a cost savings in the short term can turn out to be a costly mistake. Therefore, filter elements should primarily be replaced based upon manufactures recommendations to maintain air quality.

Secondary consideration should also be given to system pressure losses; however, for almost all modern compressed air systems, this should not be the main reason to change filter elements. The exception to this may be more applicable to older, more heavily contaminated compressed air systems, when it may be more cost effective to change filter elements before the manufacturers recommendation as the cost of replacement elements will be significantly lower than the energy cost associated with operating with higher differential pressures.

Install heat recovery

Compressing air gives heat and as much as 90% of that heat can be recovered for use in your operation. Your compressed air system represents an excellent source for heat recovery and could improve the efficiency of the system overall. Improving the performance of your compressed-air system reduces your plant wide energy costs.

Consult energy manager and expert to identify heat recovery opportunity.

If you can supplement or replace the electricity, gas or oil needed to create hot water for washrooms, or direct warm air into a workspace, warehouse, loading dock, or entryway, the savings can really add up. The possibilities to recover this waste heat via hot air or hot water are good. The return on the investment for energy recovery is usually as short as one to three years. In addition, energy recovered by means of a closed loop cooling system (for water cooled compressors) is advantageous to the compressor’s operating conditions, reliability and service life due to an equal temperature level and high cooling water quality to name but a few.

Change dryer type

Adsorption dryers are consuming lot of energy or air for regeneration and in some factories low dew point is not necessary for all consumers so dryers can be replaced with refrigeration dryers or more efficient HOC dryers.

With the help of expert calculate saving potential for replacing those dryers.

Increase system capacitance

Installed receivers and volume of main pipes are too small for your flow profile demand, causing pressure fluctuation and frequent loading of compressors. For an efficient operation of a compressed air system the size of the compressed air receiver is critical.

Capacitance (m3/bar) is defined as the amount of air needed (over what is already being supplied) to raise (or lower) the system pressure by 1 bar.

Adding bigger size of receivers/tanks is often better for system operation but also space and cost must be considered (law of diminishing returns)

Based on monitoring flow profile correct tank sizing would not be a problem.

We recommend that the receiver should be sized to protect the largest system event. You can use control storage calculator.

The minimum amount of storage recommended is 1 gallon per 1 cfm of capacity or 160 litre per 1 m3/min. This should be increased to 4 to 10 gallons per cfm or 640 litre to 1600 litre per m3/min of capacity for systems with sharp changes in demand.

Typical flow vs. power curves at various receiver sizes for load/unload lubricated compressors.

In industrial applications where air pressure is subject to large fluctuations or variations, air receivers are beneficial. In these situations, the increased compressed air requirement is compensated by air from local air receivers thus minimising idling at the generation station. The receivers subsequently replenish slowly using control valves to minimise peak energy demand on the compressor station. In addition to reduced compressor cycling, air receivers provide protection for end users that require high pressure by minimising the system pressure drop off while supporting the speed of transmission response in supply.

Install Flow controller

A Pressure/Flow Controller installed downstream of the properly-sized air storage receiver(s) and upstream of the main piping header leaving the compressor room is designed for this task. It senses the pressure at its outlet and modulates the flow control valve(s) accordingly to control the air flow from the receiver to hold the pressure constant. If more air is flowing away than in, the air expands and pressure decreases. The Pressure/Flow Controller opens sufficiently to release air from storage to bring pressure back to the set point. Conversely, if more air is flowing in than out, pressure is increasing and the Pressure/Flow Controller closes to hold air back in the receiver to correct the offset. The Pressure/Flow Controller isolates the supply side from the demand side dynamics and typically stabilizes the delivered air pressure +/- 0.07 bar (1psi) or less.

Stabilizing the pressure in the main distribution header eliminates the need to compensate for the fluctuating air pressure by raising the overall system pressure. The delivered air pressure from the Pressure/Flow Controller is set to more closely approach the minimum acceptable. Leaks and unregulated demands in the system consume less air when supplied at the lower pressure.

Significant reserve energy is available from air compressor motors that are running but not fully loaded. In combination with the Pressure/Flow Controller and air storage receiver, this reserve energy can be applied in a proactive manner to maintain an optimal balance point. As the receiver pressure changes, the trim compressor loads and unloads accordingly. For systems equipped with a network control system, instrumentation of the change allows a signal to be sent to automatically sequence the operation of the compressors in the network.

Running a partially loaded fixed speed compressor is inefficient and can be costly. Storage, therefore, is typically sized to allow unneeded compressors to time out and shut down. Ideally, all operating compressors run at full load with only one compressor trimming at any given time. Substantial air storage must be applied to cover any peaks so a shut down compressor doesn’t have to restart.

The advances in variable speed drive compressors (VSD) offer even greater opportunities to save energy and further enhance the overall performance of a system. Unlike a fixed speed compressor, there is no penalty for operating a VSD compressor partially loaded. Horsepower balances with the demand over the full capacity range of the compressor. A VSD compressor can be oversized to provide additional reserve energy without introducing an added operating cost burden.

The application of a Pressure/Flow Controller with the VSD compressor(s) offers additional savings opportunities and greater stability. Without supplemental storage, a VSD compressor tends to become reactive and ends up constantly chasing the dynamic demands, stressing the compressor motor. The Pressure/Flow Controller eliminates the oscillation and allows the VSD to operate at its maximum efficiency. Additional savings of 7-10% can be realized.

Main pipeline size redesign - high air speed in distribution line

The piping system design is crucial to operating the compressors at lower pressures. Piping configuration frictional line losses can be significant. Short-duration, high ‘surge-flow’ conditions also can affect system pressure.

Our recommendation is to operate compressed air at system pressure 6-6.5 bar (90-95PSI) or lower. If air system piping does not support this kind of pressure we would suggest to develop a generic piping schematic diagram for use in conducting a thorough system assessment.

Main ring is generally the most efficient type of distribution layout. Air mains are usually sized on velocity and a velocity level of 6 to 9 m/s (20-30 fps) is common as this is sufficiently low to prevent excessive pressure drop and should also allow reasonable water separation. The local feeding mains can flow up to around 15 m/s (50 fps). However, in order to prevent adverse pressure drops, the flow velocity in the main header sections should not exceed circa. 6 m/s (20 fps).

It is best to replace any tee connections for directional angle entry connections or swept tees. Turbulence caused by a 90o tee connection can cause pressure drops resulting in back pressure sending a false “unload signal” to the compressors which can potentially cause excessive cycling of the compressor.

Incorrect pipe sizing and restrictions are a major source of pressure losses in the system. Losses in the interconnecting distribution pipework between the compressor and the header distribution piping are commonplace however, the losses along these lines should be kept to a minimum.

Repairing air leaks and installing additional compressors and expensive controls will not rectify a basic pipe distribution system or process machine operational issue. Having too many compressors in service, needing equipment maintenance work, upgrading controls and repairing large leaks certainly are issues that need to be addressed. However, do not allow improperly sized air piping and fittings at one or two process machines in your plant to dictate a higher pressure for the entire system.

Reduce air leaks - compressed air leak management

The key to the leakage challenge lies in finding better insights and using them to support decision-making. This way, companies can find and prioritise their most effective options, and balance objectives optimally. They can reduce the number of leaks, and predict and locate those that do still occur faster and more efficiently in case of using smart leak management and zone based monitoring, supported by CALMS under Waste.

To manage leakage really effectively, companies need to optimise five linked issues:

  1. Where on the network is leakage likely to occur?
  2. When a leak does occur, how can I narrow the search area to find it as quickly as possible?
  3. What is the optimal way to organise the work of fixing a leak?
  4. How can I optimise the pressure on the network so I don’t cause leaks?
  5. How can I allocate capital expenditure so that I replace vulnerable infrastructure before leaks occur?

Leaks in compressed air systems are a regular feature. The energy requirements served by compressed air systems are intermittent in nature, however leaks are constant and surprisingly, potentially significant. The monetary cost of leaks can be quite startling and perhaps a little eye watering.

For instance, one 4mm hole in a compressed air distribution pipe can cost €2,000 per annum on a typical compressed air system operating throughout the year and at 8 bar.

In addition to the monetary cost, leaks can cause significant pressure drops resulting in excessive compressor cycling. In an attempt to reduce the pressure loss in a system where excessive leakage is an issue, operators occasionally increase the system discharge pressure. However, this has the effect of exacerbating the problem by increasing the leakage rate and create more leaks in the future.

It is not uncommon for leakage rates to be around 20 – 30%. Leaks can occur at any point in the system with joints, drains, valves regulators etc being the most common sources. Fixing leaks in the most basic form can occasionally be as simple as tightening connections or applying a sealant at a strategic point. However, leaks will be found which require replacement of faulty components. It is worth noting that one of the most effective means of reducing leakage is to reduce the distribution pressure. Note, a 10% reduction in leakage would often be achieved through carrying out an appropriate leak reduction programme.

Log equipment maintenance

Increase system redundancy - back-up compressor

Based on system review there is no adequate back-up compressor available in case of failure or service of the biggest compressor.

Our suggestion would be to have N+1 redundancy available.

N+1 redundancy is a form of resilience that ensures system availability in the event of component-compressor failure. Components (N) have at least one independent backup component (+1). The level of resilience is referred to as active/passive or standby as backup components do not actively participate within the system during normal operation.

Redundancy is a system design in which a biggest compressor is duplicated so if it fails there will be a backup. Redundancy has a negative connotation when the duplication is unnecessary or is simply the result of poor planning.

System redundancy = (Total system capacity - System flow capacity) / Biggest compressor capacity * 100%

In system review estimation we are using power instead of capacity

System redundancy:

  • < 100% - unreliable system without enough backup
  • 100% - system has backup capacity for biggest compressor
  • 100 - 200% - well designed and reliable system
  • 200% - system with overcapacity

Decrease system specific power

Decrease pressure drop across air treatment

Improve condensate management

Under average conditions, every 100 cfm of air compressed to 100 psig (6.89 barg) produces approximately 20 gallons (75.7 litres) of condensate per day which needs to be treated.

Decrease excessive distribution pressure

Our recommendation is to operate compressed air at system pressure 6-6.5 bar (90-95PSI) or lower. If air system piping does not support this kind of pressure we would suggest to develop a generic piping schematic diagram for use in conducting a thorough system assessment.

Main pipeline size redesign - high pressure drop in distribution piping

In general, fixed compressed air distribution systems should be sized such that the pressure drop in the pipes does not exceed 0.1 bar (1.45 psi) between the compressor room and most remote demand point. The pressure drop arising from flexible hoses, couplings and fittings should also be included in the pressure drop calculation. However, if possible, in an attempt to reduce pressure losses, the number of bends, valves, fittings or flow obstructions should be kept to a minimum.

An ideal distribution system provides a sufficient supply of compressed air to all demand points at the required pressure. Inadequate or poorly designed compressed air distribution systems can lead to low productivity, poor equipment performance and high energy bills. When designing a compressed air system, it is therefore good practice to consider the factors which help improve the efficiency and reliability of the compressors and ancillary equipment, minimise leakage and pressure drops and improve compressor life-cycle cost.

A useful approach is to design a ring main or looped piping system to serve the space where the compressed air consumption will take place. This is an effective way to minimise pressure drop in a system. Branch pipe connections are then run from the loop to serve the various demand points. This helps provide for a uniform compressed air supply as the air distributed to the demand point from two directions.

The design of a ring main system is a recommended approach however, may not be entirely suitable in scenarios where there are large compressed air consumers located at a much greater distance from the compressor installation. It is recommended that a separate compressed air main should be routed under these circumstances to serve this equipment.

Inadequate documentation - collect and update project documentation and PI&D

Possible high temperature in compressor room

Improve cooling air quality

Increase or clean space around equipment for service accessibility

Improve daily equipment checklist

Design and add spare connection for rental equipment in emergency situation

Consider doing a yearly audit

Consider purchasing new equipment - compressors to replace old ones

Consider using a service contractor for compressors that performs preventive maintenance to keep possible downtime to a minimum

Consider overhauling or replacing old compressors

Inadequate redundancy of compressors

Install a bypass across filters and dryers

Order new equipment maintenance

Equipment regular service is very important for reliable and efficient compressed air system operation.

Perform an external audit

Start using CALMS smart monitoring

Organize training for your employees

Ongoing employee training helps cultivate talent from within your business. By retraining employees on current skills, you can increase productivity by preventing small, basic mistakes.

Replace filters more regularly

Check condensate drains regularly

Under average conditions, every 100 cfm of air compressed to 100 psig (6.89 barg) produces approximately 20 gallons (75.7 litres) of condensate per day which needs to be treated.

Change desiccant

Conform to standards

Start new trainings for employees

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