Only one pressure in your compressed air network?

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I am amazed to see only single pressure networks, even in the largest factories with over 2000 employees and 5 or 6 large compressors in a row. There is 7 bar everywhere. However, I was in a cookie factory, where more than half of this air was used for blowing the crumbs from the machines. You don’t need 7 bar for that! Compressed air is a very expensive form of energy and it would be much cheaper if part of it were supplied also at a lower pressure, where appropriate. It is like providing water at two temperatures. Can you imagine having only one tap for hot and not for cold water, all over the factory, and also home? How long would it take for you to realise the inefficiency of such a single network and fix the situation?


I was wondering if air could not be compressed at two different pressures and asked a Solution Engineer of Atlas Copco in Switzerland his opinion about the following three ways to do that:

  • Two different compressors in the central compressor room and two different grids. This can also be so configured that the air for the low pressure grid is taken from the first stage of the compressor and the second stage takes the air that is left from the production of the low-pressure-unit minus the consumption at low pressure, to input it into the high pressure grid. The Solution Engineer said that this requires the exact synchronisation of the high pressure unit with the consumption at low pressure. It seems better to have simply two compressors and two grids. It will still save energy! And parts of the existing grid may be reused for the low pressure if in some department there is no need for two pressures.

  • One low pressure machine in the central compressor room and another in some department of the factory, where high pressure is required. So there is a low pressure grid in the whole factory that feeds also the peripheral higher pressure machine. This compressor supplies its local higher pressure grid. Apart from the dislocation of the high pressure compressor, this is similar to the previous situation. The Solution Engineer told that this is done for example with blowing PET bottles at 40 bar. With a compressed air storage, the synchronisation hasn't to be precise.

  • One normal high pressure machine in the central compressor room for the grid in the whole factory. A few mobile low pressure machines are used where lower pressure is sufficient. This is often used for cleaning, so mobile compressors make sense! The Solution Engineer said that if the need for low or high pressure is divided between departments, so that there are not many areas where air is needed at two different pressures, it would be more practical to have a fixed grid. So in the particular case that no area has need for two pressures, the existing grid needs only to be separated in two different grids.

Moreover, the engineer said that at the usual pressure, each bar reduction will save 7-8% of energy, so it makes sense to decrease the pressure with trial and error at the lowest possible pressure with some margin to allow for pressure reduction during high consumption. Such a pressure fall can also depend from a non sufficient diameter of piping!

A tip that seems to be known on a limited scale is to keep the inlet temperature of air compressors low. I saw even large factories with many compressors, all in a row in a machine room, taking the inlet air from that same room, even in summer. The inlet air must respect the quality requirements of the manual, but the temperature must be at the lower limit for maximum efficiency. Once, in a large factory, I saw next to the machine room a tunnel that was running under the whole factory. That is a good source of constant temperature inlet air during the year.

The need for Energy Managers for the Energy Transition

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Energy Efficiency is behind on Renewable Energy as the International Energy Agency (www.IEA.org) confirms here

Is the one better, convenient of cleaner than the other? No. As I explain in my blog on the Trias Energetica they fit to each other. In short: you don't want to waste renewable energy in inefficient production plants. An efficient consumer will require a smaller renewable energy system and save on its investment. The problem is to optimise the combination, which requires a quicker development of energy efficiency.

How can we change that? A good start would be to delegate it to your new Energy Manager and support her/him. Then it will depart “automatically”! And how? 

Like Schneider Electric states, on the long run the Energy Manager can save for your organisation up to 30% in 3 phases:

  1. Passive Energy Efficiency (like new tech with higher conversion efficiency, insulation, …); 

  2. Active Energy Efficiency (automated switching, human behaviour, setpoints); 

  3. Monitoring and maintaining savings. 

 

And how do you get quickly an Energy Manager, but a real one? Not a general technical person that has Energy Efficiency as a “nice if” task, if there is time over!

I would say, select from your technical staff an engaged, experienced and outgoing person and train her/him with a compact course. Birdseye Energy School already launched a course online, it is short enough for a quick start (saving time and money) and complete enough to empower the new Energy Manager in a lot of different situations. A quick start will allow to have quick results and a positive feedback from the decision-makers. The Energy Manager can learn by doing and take later additional courses for specific subjects. Birdseye is preparing small learning units for specific technologies (how to safe energy with compressed air, HVAC, light, heat recovery, Demand Side Management, …) and different industries (machines, food, paper, waste, …). Also measurement and monitoring will have an apart course.

Because Energy Efficiency is complex and requires a multitude of made-to-measure solutions in each enterprise, we need in each enterprise with 1 million $ a full time Energy Manager and a shared Energy Manager for the smaller enterprises. They will repay their cost, not only with the savings on the energy bill but also with collateral benefits.

Birdseye Energy School is focused on teaching to find these collateral benefits that will not only increase the cash flows but also make happy other persons in the enterprise, which will be directly affected by these benefits, for example the Safety & Health Manager with better lighting and the Production Manager with higher yield after installing heat recovery. There are many examples of collateral benefits and the training enterprise sellingenergy.com in California is one of the first that started teaching this concept.

The Dutch "Wipe Pulse" for saving on lighting

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Imagine an office building. It is night and many lights are still switched on. Are there really people there working, or maybe a few teams are cleaning the offices? Is this a picture taken at a time that they are cleaning offices or maybe at 3 o'clock at night? I don't know but I imagine that many offices are looking like this during the whole night and not only the night that this picture was made! And what about lunchtime? It might be only one hour but still, leaving on the lights during this hour is  wasteful.

What is the matter here? You imagine it. People just leave the lights on. 

So what will you do in this case? Presence sensors? Good hit. They are indeed applied in many places, especially when people are not too often in the room, when the off-time would be significant in comparison with the on-time (so the energy saving is significant) and when the switching doesn’t disturb. If you are in a storehouse, this may work well. In an office or even factory, people are usually all time there and it doesn’t make much sense to work with presence sensors. There is the risk that if people are sitting still, presence sensors switch the light off. That may require attention during the configuration of the sensors or buying advanced, more expensive models.

In shops, presence sensors are not applied much and shop owners would not like to consider it, I imagine. People might stay away if they see that the shop is dark or semi dark.

In the Netherlands, they came already decades ago with the “veegpuls”. How do you explain this word in English? Maybe Wipe-Pulse is the best translation. A few times during the day, for example at lunchtime, after work (5:30 PM) and certainly after cleaning hours, all lights (excluded a few with presence sensors) are switched off centrally. If someone decides to stay in the office or hall, for example to lunch while surfing the internet or in the evening to do overwork, it is simple to stand up from the seat, walk to the switch and walk back to your place. So then you may be sure that light is on, where it is needed and only there. This needs a network where all lamps can be controlled centrally and locally. People also become aware that energy is saved in this way and might extend this awareness to other places without the swipe pulse. Maybe at home.

The list of collateral benefits (I want you to provide with such a list for each Energy Conservation Measure that I write about):

  • It is relatively simple, apart from the need to have central command over all switches. It doesn’t require a complicated installation, configuration and there is no investment in many presence sensors with each its own configuration of sensitivity and switching time. This advantage may appeal to management because of the lower investment and less labour for the set up.

  • The building users are left in freedom. They have at most to stand up from their seats twice a day. The lights are switched of 3 x a day, this is not much. If compared with lights that are often switching in rooms where people are present, it will disturb less.

  • If people are sitting still, presence sensors might switch the light off. That is not good. So the swipe pulse gives more comfort in this sense, too.

  • Energy is saved especially during many hours in the night. This saves money and reduces the need to cool the produced heat away when people are arriving in the morning.

  • People are made aware of energy saving.

Your bonus

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You will have access to a free course of 2 hours about Energy Management, which has a price of 15$ on my course platform. The course can be found on:

        https://birdseye-energyefficiency.learnworlds.com/courses

 

This cours with 3 lessons teaches about the situation today with Energy Management in large organisations and complex energy users (I stay away from the Energy Efficiency in the residential sector, where many services are already available), and why there is so much room for improvement. Knowing this unlocks the door to the solution already! I also explain the ISO 50'001 and how it can help the enterprise. Finally I explain how Birdseye Energy School can help you to improve the situation in a concrete way.

During the purchase you use the following coupon to cover the entire cost of the course:

         FreeCrs

You fill it in the coupon area on the purchase page (no need to fill in the credit card fields). You click "Redeem" and the total sum will go to 0. Then purchase it and continue to the course.