More than 90% reduction of discharge water in the Schuberg Philis data centerArjan Westerhoff
A few years ago we successfully reduced 86% of electrical energy using our new cooling installation in the data center. The new cooling installation is a combination of cooling towers and aquifer thermal energy storage (WKO). Together with a new distribution system, optimized in-room cooling units and, most importantly together with a great team, we were able to achieve this result.
After all these years it's working great, but there was one thing ....the water consumption
It started with one of the colleagues of Schuberg Philis who was walking outside of the data center and heard a lot of water draining into the sewer. When hearing this he asked himself: why are we using such an amount of water for a cooling process and after that it's going to be wasted? It shouldn't be this way.
Since then, we have been searching for a better technique to improve our water consumption. We came across Frans Durieux from the Aqua Innovation Network, who is a water treatment expert, and as such, he was familiar with David Sherzer from Universal Environmental Technology (UET), who many years ago discovered and developed a water conservation technology, which is used all over the world, but not before in the Netherlands.
Water treatment in cooling towers
The main issues with water in cooling towers are scaling, corrosion and biological growth. The chemical solutions are anti scalants, anti-Oxidants and Biocides. The anti scalants bind ‘the hard minerals’ in the water, which avoids scaling to a degree but makes the water aggressive. Anti-oxidants solve this (self-inflicted) problem and should avoid the water to attack steel and copper piping. Biocides are dosed to control the biological growth. There are several negative aspects to doing this:
- Avoiding scale with anti scalants is limited in its effectiveness, causing a need for a high blow-down of (chemically burdened) waste water.
- Once deposits are formed they will not be removed by dosing of anti scalants.
- Biocides take time to become effective, by which time they might be discharged already
- The water quality will vary in time, but the dosing remains constant so the dosing is never spot on.
The chemical treatment goal is to avoid the natural way of water, which is to scale when concentrations build up. This is a dangerous fight, with deposits on one side and corrosion of the heat exchanger on the other side of the narrow path that needs to be taken. The biological fight is a different one but with even larger and potentially lethal consequences. This fight takes a regular check on effectiveness which too often prove to be insufficient due to wrong set points, empty buffers and failing pumps. These fights can be won, but still take a limited water effectiveness, causing one third to half of the feed water to be discharged.
David Sherzer worked in a large industrial complex (bromine compounds industry), and got frustrated by the philosophy of adding chemicals to water in order to avoid water’s tendency to form scale. Why work against nature when there might be ways to achieve the same goal in a different way: not to fight water’s tendency to produce scale, but to encourage the water to do it in a desired place instead of an undesired one. After some tests, he started Universal Environmental Technology (UET), in order to bring this vision to the market within a new technology.
The core of this patented technology is a chemically engineered reactor driven by a controlled partial electrolysis, taking place in an electrically charged tubular reactor. The outside of this reactor is negatively charged, causing, among other reactions, a higher concentration of hard minerals (Calcium, Manganese, Silica, etc.) and a high pH. This leads to scaling within the reactor. A positively charged anode is placed in the middle, where chlorine is produced from the naturally occurring chlorides in the water. This reactor is placed in a side stream of the cross flow of the cooling tower (typically about 10-25% of the flow), resulting in disinfection of the whole system, depressing corrosion processes and avoiding scaling in undesired places. This technology brought to the world the opportunity to clean water systems from historical deposits, without adding any acid and without an acceleration of corrosion processes, all without stopping the cooling system. Oxidation issues are avoided by controlling the amount of hard minerals in the water in such a way that they are just below saturation point. This keeps the water from being aggressive, hence no oxidation of metals as Zinc, Copper or Ferric will take place.
With this technology, water consumption is reduced, as the undesired minerals are removed from the water instead of them binding together. This saves money on both the intake and the discharge of water, and results in no more chemicals, saving money as well. The UET technology is not like generic chemicals, and successfully treats cooling systems using make-up from potable-, ground- and river water.
The project of changing chemical water treatment with UET's chemical treatment included the following steps:
We performed water sample analyses from the cooling towers and the ground water. Unfortunately, the amount of iron in the ground water was too high, so we decided to use potable water, as a first stage.
We gathered engineering data relating to the existing cooling installation - the cooling towers, heat ex-changer, pump, pipelines, flow, etc., including readings and controls from the Building Management System.
We approached the manufacturers of the cooling installation components (cooling tower, heat ex-changer & pump) with information regarding the UET technology, and its predicted water analysis. Both the technology and the results were approved by them.
These water treatment results were submitted to the local authorities with regards to legionella management, and were proven to comply with regulations.
The UET unit was designed, ordered, integrated into the cooling tower and operated for several months.
The UET unit started up by simply putting it on, shutting the dosing pumps off and increase the discharge set point from 1250 to 5000 uS/cm (at that time the maximum set point)
Change the blow-down controls: new conductivity measurement (higher range) and blow-down valve, and give new set point of 6000 uS/cm
After several months, during which we performed constant water analysis, the UET reactors were opened and impressive amounts of scale were scraped out of them, instead of settling inside the cooling system. According to the ion balance that was made, we could prove that a historical amount scale was removed from the system. Cooling tower experts were surprised to find out that historical scale can be extracted from water systems, without using any acid. An additional surprise was that we did not need to stop the cooling system during the cleaning. So, not only did we buy a water treatment system, the added bonus was that we also received a cooling system cleaning device, without additional cost.
Since the commissioning of the new water treatment system we have taken multiple water samples, and could confirm that the amounts of the following minerals are all within specification: Calcium, Magnesium, Silicon, Iron, Chlorine, Sulfate and Carbon trioxide. Additionally, the pH and bacterial count, including legionella, were also improved in comparison to the conventional treatment.
We used to consume 600 liters of chemicals for water treatment every year. Now we are chemical free.
With this water treatment system we can’t affect the evaporation ( the cooling process itself ), that’s why we talk about the more than 90% reducing instead of the more than 40% of total water reducing.
Note: these results are based on the first four months of the water treatment installation in operation and when we only use the cooling towers for cooling the data center and based on the outside climate conditions on that moment. When we use the cooling towers for cooling the data center and storing cooling capacity in the ground we use more make-up water. Next to that the outside climate condition will influence the water usage.
Review of the project objectives
Reducing water – UET's technology in operation brought more than 90 % reduction on the blow-down.
Total chemical elimination – since the UET installation, no chemicals have been injected into the system.
Cost reduction – the UET technology, according to the onsite performance, shows less than a 1.5 year return on investment.
Improve heat exchanger efficiency - by not having scale on the heat exchanger, which would act as a heat transfer isolator.
Reduced corrosion acceleration – UET's technology reduces corrosion by operating under scale formation conditions, without forming scale in the water system.
The effectiveness of the cooling installation should be taken in account when looking to the water consumption of a data center.
On a yearly average base we consume 0.19 kW electrical energy for the cooling of 1 kW of electrical energy IT equipment. The efficiency factor of the cooling installation is 5.2
These calculations an numbers give a transparent view of the efficiency then when using the PUE metric. Within the PUE metric other facility’s energy uses are included.
Explanation of technical phrases
Make-up water : this is the fresh supply water
Blow-down water : this water will be drained in the sewer
Evaporation : this is the cooling process itself
Thanks to Frans Durieux from the Aqua Innovation Network & David Sherzer from UET we are one step further to a more sustainable world because we are reducing millions liters of water every year and we are chemical free!
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