Tag Archives: monitoring

Sensors

Monitoring Transportation

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Rotronic has recently released a cold chain logger which can be used to ensure items are kept at the correct temperature during transportation.

tl-cc1_0094Rotronic cold chain logger

Transportation in general

One key aspect of today´s wealth in the modern world is specialization. So towns, regions or even whole countries focus on a few things they are really good at. This can be based on various factors; for example resources offered by the land, climatic conditions or specific knowledge that has been developed over a long period and has been passed on from generation to generation. As an example, Cuba provides brilliant conditions for the Corojo and Cirollo plants, better known as tobacco. Although smoking is quite popular among Cubans, their production of tobacco exceeds the local demand by far. On the other hand they lack other resources and goods. At that point trading, and therefore the importance of transportation, comes into play. In the case of the tobacco the transportation is not a simple task, since it requires a constant high humidity level to maintain the high quality expected from a Cuban cigar.

Tobacco-Fields-in-VinalesTobacco plants in Cuba

Like tobacco there are many products where special requirements for shipping have to be put in to consideration, in order to maintain freshness, internal integrity, colour quality or whatever other properties that could be affected by an inappropriate transportation.

Facts & figures:

A major step in the transportation industry was the international standardisation of shipping containers in 1955. This means that one container can be put directly from a vessel to a truck and transported all around the globe.

Today 28´000´000 ISO containers (20 feet) are permanently on the move, transporting goods from point to point keeping our economy running.

Every year 10´000 shipping containers fall over board.

0.16 Euro cents is the cost of transporting a bottle of Chilean whine to Europe.

Why the need to monitor transportation?

Various factors can have a negative impact on a product during transportation. Below are the most common parameters to be monitored to ensure product quality:

Temperature

Controlling temperature is the key in transporting fresh foods, where the rate of decomposition is reduced significantly by maintaining lower temperatures. It is also important as proof of an uninterrupted cool chain for frozen products or to ensure the effectiveness of medication.

truck_insidesthe back of a temperature controlled lorry.

Humidity

Monitoring humidity ensures that the growth of micro organisms in food and medications remains below critical levels. Controlling humidity also helps to maintain structural integrity of paper and cardboard or to avoid corrosion of metals during a long transatlantic journey in a shipping container.

Pressure

Apart of being able to reconstruct when and how long a parcel`s flight was, pressure is also en essential parameter for products that have to be transported in a vacuum or pressured chamber. This method could for example be used when transporting biological samples or hazardous chemicals.

Shock

To guarantee that expensive machinery, glass, works of art and other delicate products weren’t damaged during transportation, monitoring of the G-force in all three axis is the solution.

Rotronic-HygroLog-Log-HC2-P1-Universal-Humidity-and-Temperature-Data-Logger-Humidity-and-Temperature-Measurement---Large-21391770915

 

The Rotronic LOG-HC2 can log light, temperature, humidity, pressure, and shock.

Light

Light is a good parameter to determine if or at what time a container or package was opened. Also to ensure protection of light sensitive products such as vegetable oils, chemical substances or photo paper.

Philip Robinson                                                                                                       Rotronic UK

CO2, Sensors

CO2 and Indoor Air Quality (IAQ)

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Indoor Air Quality in General

The quality of the air in a room can greatly affect the health, productivity, and well being of any occupants. Previously the temperature and humidity of indoor air were considered as the most important parameters contributing to air quality, but there are several other factors which must be taken into account.

Indoor Air Quality (IAQ) problems are very often caused by gases or particles released into the air by pollution sources. This can be avoided by carefully selecting the materials which are to be used inside dwellings, offices, classrooms, gymnasiums, hotels, shopping malls, hospitals and in all en-closed spaces which are inhabited. But there is another source of air pollution, which cannot be avoided. this other source is people themselves. Every time a person exhales, CO2 is released. Inadequate ventilation may increase CO2 concentration to an unhealthy or even life-threatening level.

carbon_dioxide_3d_ball

CO2: made up of 2 oxygen atoms, double bonded to a single carbon atom.

The most important control parameters for a good Indoor Air Quality are temperature, relative humidity and CO2 concentration. If these values are used with an intelligent air conditioning system, an energy efficient air supply can be used to produce a high quality atmosphere.

Facts & figures:

CO2 is a naturally occurring molecule consisting of two oxygen atoms and a single carbon atom.

At standard temperature and pressure CO2 is a gas, invisible and without any smell or taste.

CO2 is 50% heavier than air and has no liquid state under atmospheric pressure.

In the earth’s atmosphere CO2 has a concentration of 390 ppm by volume.

The worldwide industry produces approximately 36 billion tons of CO2 per year.

Industrial activities are responsible for an increase of atmospheric CO2 concentration and thus for an increase of global warming (greenhouse effect).

Influence of CO2 on Humans

Only a small amount of the atmosphere is made up of CO2, the prevailing components are nitrogen and oxygen. The natural outdoor atmosphere CO2 level is approx. 390 ppm. Increasing this concentration causes several symptoms of poisoning, ranging from drowsiness at around 1´000ppm to unconsciousness and even death at above 10´000 ppm. Even if a  rise in CO2 concentration has not yet severely influenced the health of people, it may reduce their productivity, efficiency and well-being.

270px-Main_symptoms_of_carbon_dioxide_toxicity.svg

 

Some of the possible health effects

How to Measure CO2

The most common measuring method for CO2 concentration nowadays is based on a spectroscopic principle. Sending infrared light (IR) with a wave length of 4.23 μm through a gas sample. CO2 molecules in the sample absorb the light at this wavelength. an IR sensor is then used to detect any changes in the energy levels of the light after passing through the sample. The more C)2 in the sample, the more of the light that will be absorbed, and the weaker the IR signal will be when it reaches the sensor.

ndir-sensor_1

Example of an IR CO2 sensor

The sensitivity of a CO2 sensor increases with the length of the light path through the sample gas. Thus the sensor used in Rotronic CO2 measuring devices makes use of multiple reflections of the IR beam on the walls of the probe chamber. this means the small CO2 sensor (2.5 cm x 5 cm) has a measuring path length of 12.5 cm and is accordingly sensitive. This type of sensor is called a NDIR (Non Dispersive Infra Red) sensor. This means that a broadband IR light source is used and the measured wavelength is filtered out at the end of the beam in front of the IR detector.

Why the Need to Measure CO2

New energy efficient demands lead to more airtight buildings and ventilation being completely turned off at night. Intelligent HVAC systems must be able to adapt themselves to situations with changing occupants of rooms. One answer is Demand Controlled Ventilation (DCV) with built-in CO2 sensors. By using DCV, huge amounts of energy can be saved without any drawback for the occupants. According to a study of the UN Climate Panel 40-50% of world energy is used in buildings. Only the adoption of the EU Directive on Energy Efficient Buildings would result in saving 30-45 MT of CO2/year. As HVAC (Heating, Ventilation and Air Conditioning) is responsible 40-65% of energy usage in commercial and public buildings, a balance between comfort and energy saving must be found.

HVAC

A large HVAC system

One example demonstrates the evidence of CO2 controlled room ventilation. The exhaled air of a human contains up to 40´000 ppm CO2. In one hour a person breathes out 15 litres of CO2. Thus in a classroom with a volume of 200 m³ occupied by 25 pupils the CO2 concentration increases in one hour by 1´875 ppm!

Especially in wine cellars, breweries, the beverage industry and other industries in which CO2 may be produced or processed the constant measuring of CO2 concentration is absolutely vital to prevent a deadly threat to the employees. This is not only a rational procedure but is also enforced by official regulations in nearly every developed country.

Philip Robinson                                                                                                       Rotronic UK

Meteorology, Sensors

Wind Turbines

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Its been pretty windy recently, So wind farms are probably doing quite well at the moment. The biggest wind farm in the world, at the moment, is the London array, which can produce 630MW of power.

Wind Energy in General

The future is very encouraging for wind power. The technology is growing exponentially due to the current power crisis and the ongoing discussions about nuclear power plants. Wind turbines are becoming more efficient and are able to produce increased electricity capacity given the same factors.

Facts & figures:

There is over 200 GW (Giga Watts) of installed wind energy capacity in the world.

The Global Wind Energy Council (GWEC) has forecasted a global capacity of 2,300 GW by 2030. This will cover up to 22% of the global power consumption.

WindPower
Converting wind power into electrical power:

A wind turbine converts the kinetic energy of wind into rotational mechanical energy. This energy is directly converted, by a generator, into electrical energy. Large wind turbines typically have a generator installed on top of the tower. Commonly, there is also a gear box to adapt the speed. Various sensors for wind speed, humidity and temperature measurement are placed inside and outside to monitor the climate. A controller unit analyses the data and adjusts the yaw and pitch drives to the correct positions.

The formula for wind power density: 

W = d x A^2 x V^3 x C  

d: defines the density of the air. Typically it’s 1.225 Kg/m3. This is a value which can vary depending on air pressure, temperature and humidity.

A^2: defines the diameter of the turbine blades. This value is quite effective with its squared relationship. The larger a wind turbine is the more energy can be harnessed.

V^3: defines the velocity of the wind. The wind speed is the most effective value with its cubed relationship. In reality, the wind is never the same speed and a wind turbine is only efficient at certain wind speeds. Usually 10 mph (16 km/h) or greater is most effective. At high wind speed the wind turbine can break. The efficiency is therefore held to a constant of around 10 mph.

C: defines the constant which is normally 0.5 for metric values. This is actually a combination of two or more constants depending on the specific variables and the system of units that is used.

nordex-wind-turbine-450-x-299

Why the need to measure the local climate?

To forecast the power of the wind over a few hours or days is not an easy task.

Wind farms can extend over miles of land or offshore areas where the climate and the wind speed can vary substantially,
especially in hilly areas. Positioning towers only slightly to the left or right can make a significant difference because the wind velocity can be increased due to the topography. Therefore, wind mapping has to be performed in order to determine if a location is correct for the wind farm. Such wind maps are usually done with Doppler radars which are equipped with stationary temperature and humidity sensors. These sensors improve the overall accuracy.

Once wind mapping has been carried out over different seasons, wind turbine positions can be determined. Each turbine will be equipped with sensors for wind direction, speed, temperature and humidity. All of these parameters, the turbine characteristics plus the weather forecast, can be used to make a prediction of the power of the turbine using complex mathematics.

wind-turbine-controlThere is a small weather station on the top of this wind turbine

The final power value will be calculated in “watts” which will be supplied into power grids. Electricity for many houses or factories can be powered by this green energy.

Why the need to measure inside a wind turbine?

Wind farms are normally installed in areas with harsh environments where strong winds are common. Salty air, high humidity and condensation are daily issues for wind turbines.

Normal ventilation is not sufficient to ensure continuous operation. The inside climate has to be monitored and dehumidified by desiccant to protect the electrical components against short circuits and the machinery against corrosion.

Internal measurements are required to ensure continuous operation and reduce maintenance costs of a wind farm.

Philip Robinson                                                                                                       Rotronic UK

CO2

Chicken Hatcheries.

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As it is nearly Easter, I thought it would be a good idea post something related to eggs, unfortunately not the chocolate kind…

Chicken hatcheries in general

It takes about 21 days to hatch a chicken and during that time, it is crucial that the surroundings are controlled for it to be successful. Egg hatching farms transform the chickens into “broilers” or egg laying hens. Meat from egg hatching farms is the most consumed worldwide.

Facts & figures:

Approximately 49 billion chickens are consumed worldwide every year. That is 134 million every day.

Chicken is the most common type of poultry in the world.

100g of baked chicken breast contains 4 grams of fat and 31 grams of protein.

Sustainability of chicken meat increases by 20%, when using CO2 for modified atmosphere processing.

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Why the need to measure CO2?

Less staff required to run the breeding stations thanks to all hatching happening at around the same time. This means it is easier to plan shipments and know how many birds can be transported at a time. This results in less capital and reduced transport costs.

A smaller number of birds die during transportation, which results in more profit per shipment and less feed losses.

More efficient and cheaper feeding options, both through feed reduction and reduction in time.

Chickens_eating

Faster and easier to slaughter the animals using CO2, and there is no unnecessary suffering to the birds.

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Packing using CO2, means food will last longer in supermarkets and for customers once purchased. This means a reduction in food waste from expired food.

How does it work?

The fertilized eggs are placed in a chamber, in which CO2 levels are controlled, depending on what stage of development the eggs are in. Living eggs contribute to the levels of CO2 (not 100% of all eggs are alive), which means that you have to monitor the CO2 continuously.

It has been shown that during embryonic development, the supply of CO2 has positive effects on the health of the organism after birth. Control of CO2 in chickens in development has also led to a more controlled hatching time.

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Once CO2 levels insid an egg reach a certain level, the fully developed chickens start to hatch. When the chick has hatched, oxygen will be supplied. Once the eggs are hatched, they are sent off in trucks where the birds continue to develop during the transportation. To ensure the good health of the chicks during their transportation, the CO2 levels in the truck are controlled for the whole journey.

It has been found that a bird’s metabolism works slower at high concentrations of CO2. Controlling CO2 levels therefore means it can take less time and less food to raise broilers or egg laying hens. This means production will be cheaper for the companies, it´s also more sustainable to use less feed per pound of chicken.

The chickens are slaughtered after being knocked out with high levels of CO2, which only take a few seconds. This method is more humane than killing by electrical stunning.

Philip Robinson                                                                                                       Rotronic UK

Humidity, Sensors

Timber Drying

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We recently visited a company which is involved in the drying of wood, and learned a bit about wood drying. This company had bought a temperature and humidity logger for monitoring their drying environment.

Timber Drying in General

Wood is probably one of the oldest building materials on the planet. But before wood can be used as a construction material, whether it for structural support in a building or to manufacture furniture, it has to undergo treatment to gain the required properties defined by the application in which the wood is used. The first and most important treatment is the drying process.

MINOLTA DIGITAL CAMERAA timber frame for a barn.

The fastest and most effective way to drying timber is in a Kiln. Kiln drying is done in a closed chamber in which air temperature, relative humidity and airflow can be controlled to dry timber to a specified moisture content. The temperature for the drying is usually between 40-90°C depending on type, size and the intended use of the timber. There are many different types of kilns such as vacuum systems, traditional heat and vent type kilns and radio frequency dryers. The cost of installing and maintaining a kiln may often be prohibitive unless a large amount of timber can be processed. However, if the value of specific species is high enough, it becomes more feasible to kiln dry green timber.

Drying_process2Wood in a drying kiln.

Some other drying options timber include: Solar drying where the green timber gets put into a glass house. This option is more often used for drying small amounts of timber. For bigger amounts the Air drying option tends to be used more often. Both drying options are only controllable to a very limited extend since they strongly depend on weather conditions.

Facts & figures:

One cubic metre of freshly felled oak contains approximately 540 litres of water.

Examples for air drying times:

Softwoods: 25mm thick Scots pine that is stacked in April can reach 20 % moisture content by July to August if the summer months are warm and dry.

Hardwoods: 25mm thick English oak if piled in early autumn can reach 20 % moisture content in about 10 months.

A 75mm thick log of wood can even take 3 years to reach equilibrium moisture content.

Why the need to measure humidity?

Controlling humidity during the timber drying process is essential for many factors. An incorrect level of % Equilibrium Relative humidity (ERH) in wood can have the following effects on product and process:

OLYMPUS DIGITAL CAMERAWhen damp, wood is easily damaged.

Dimensional changes

A controlled drying process prevents the timber from unacceptable shrinkage after the installation. But since wood is a natural hygroscopic product it will always change its size to a minor extend.

Strength

Drying the timber below a water contents of 25 % to 30 % will maximise the mechanical strength. dry wood is nearly twice as strong and twice as stiff as green wood.

stess_moisture_plotAs moisture content of wood decreases, the strength increases.

Decay

After drying, timber maintaining less than 20 % moisture content is unlikely to be attacked by wood decaying fungus.

Preservation

To increase the effectiveness of preservative treatments. Many preservatives should only be applied when the humidity of the timber has been reduced.

Corrosion

Drying timber prevents the corrosion of metal fixings such as  nails and screws.

rusty-fixingsWhen wood is wet, it may corrode metal fittings.

Weight

Dry wood is much lighter in weight than wet wood. For many species, dry wood is nearly half the weight of wet wood.

Philip Robinson                                                                                                           Rotronic Uk

Humidity

Humidity and Seed Storage

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I recently visited a facility where they were doing a lot of research into plant biology. As such, it was important for them to have their seeds stored at exactly the correct temperature and humidity to prevent germination or degradation of the seeds.

Seed storage in general

Around 10000 years ago when the first human beings stopped hunting and gathering wild plants, and started to cultivate on farms, preserving and storing seeds became important.

There are various reasons to store seeds, for example, simply preserving grain for consumption later in the year or for sowing during the following season. A little more complex is the collection and preservation of seeds for a longer period of time. This may be done to protect species from extinction or to ensure genetic variety for future generations. Long term storage is also necessary as a back up in case of catastrophic events, such as natural disasters, and disease outbreaks. This type of long term storage is usually done in well protected storage building called seed banks.

Seed-Diversity-in-the-Mil-007A range of seeds in storage

Inside each seed is a living plant embryo which, even in a state of dormancy, breathes through the exchange of gases across its membrane, and is constantly undergoing metabolic processes, also known as aging. The natural lifespan of a seed is influenced by several factors including: permeability of the seed coat, dormancy, and seed physiology. But one of the most important factors is the external environment the seed is exposed to. Temperature and humidity play a key role in the storage capabilities of seeds.

Facts & figures:

The oldest seed that has grown into a viable plant was a Judean date palm seed about 2,000 years old.

The Millennium Seed Bank Project in the UK is the biggest seed bank in the world. Currently they store 31880 species and 1`907`136`030 seeds.

China, with 197 million metric tons, is the world`s biggest producer of rice.

 

Why the need to measure humidity?

Controlling the environment in seed storage is essential for maintaining the germination capacity of seeds, or simply the quality of the seed as a food.

iregi_siteSunflower seeds

In General

Every 1% decrease in the moister content will double the storage life. The same applies for every 5°C decrease of the storage temperature.

A rule of thumb: the sum of the temperature in degrees F and the % relative humidity should be less then 100 for good seed storage conditions.

Storage conditions

Proper storage conditions maintain relative humidity levels
between 20% and 40%, giving corresponding seed moisture contents between 5% – 8%, depending on the type of seed. This range is safe for most seeds. When seed moisture content drops too low (<5%), storage life and seed vigor may decline. When seed moisture content goes above 8%, aging or seed deterioration can increase. Deterioration effects the integrity of the cell membrane, along with several biochemical processes, which overall results in loss of vigor and viability. Seed moisture contents above 12% will promote growth of fungi and insects. Most seeds cannot germinate until seed moisture contents go above 25%.

seedgrowthA newly germinated seed

Seed preparation for long term storage (Seed bank)

To prepare for long term storage, seeds are first put in to a drying room where temperature and humidity is carefully kept at 15°C and 15% relative humidity. Under these conditions the seeds gradually dry out. They are then cleaned, counted and put into airtight containers, before being placed in a seed bank at -20°C. The seeds are then tested for viability on a regular basis.

Philip Robinson                                                                                                                        Rotronic UK

Humidity

Humidity in Archive Stores

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We recently visited a record office to help set up a wireless temperature and humidity logging system in their archives. They had been experiencing problems with mould growth on the records, some of which could be over a thousand years old. To reduce the levels of damage to the records, they wanted to be able to closely control temperature and humidity levels.

Archives in general

Archives are an accumulation of historical documents collected over the life-time of an organisation.

National archives collect, catalog, and secure historical & present day materials from their country. Besides preserving & organising collections, archivists face the great challenge of deciding which records are assigned a lasting value for research purposes and could contribute to the understanding of the country’s history.

Furthermore, archivists transfer the information to more resistant media by digitising documents, drawings, and photographs. This makes it easy for researchers to access conserved items without the risk of damaging the originals.

OrphicPrayerSheet, 3rd Century BCE

Ancient  Etruscan script

In spite of all the new media available these days some legacy materials need to be preserved in order to show their uniqueness. The oldest preserved book in the world is possibly an Etruscan script discovered in Bulgaria. It is estimated to be more than 2,600 years old.

Besides all the academic work necessary it requires great technical effort to create the best possible storage conditions suitable for the form of the objects to be preserved. For example; papyrus and paper require different temperature and humidity conditions compared with microfilm tapes.

Environmental factors in archive stores

– Radiation in the form of light will cause paper to yellow and ink to fade considerably.

– Air pollutants such as dust and chemicals accelerate the degradation of important documents.

– Vibration for example of archive stores caused by vehicular traffic or construction work can cause mechanical stress on collections.

– Insect pests can lead to severe damage through bites and deposits.

– Temperature & humidity are the most significant factors that have an impact on archive collections and often interrelate with other environmental factors.

Why the need to measure relative humidity?

As in museums, incorrect temperature and humidity levels cause damage to documents, books, photographs and drawings. The rate of decay can double with an increase of as little as 5 °C. Generally warm & damp conditions provide more energy and so increase the speed of decay.

High temperatures can cause document wax seals to soften and even result in the combustion of cellulose nitrate film. At low temperatures organic and plastic materials become brittle making them prone to physical damage. However, one of the most significant consequences of incorrect temperature is the incorrect relative humidity that can result – temperature has a direct effect on relative humidity and vice versa.

This particular fact of course is the same in museums, but is often much harder to control in archives since proper ventilation is not easy to achieve in between multiple shelves fully loaded with collections. Studies have shown large deviations of temperature and therefore also humidity (RH) within an archive section. In general, it is recommended to keep the temperature between 20 – 22 °C and humidity be-tween 50 – 60 %rh in archives where organic material is stored. Otherwise a temperature drop can make condensation inevitable.

book1

A damaged book.

RH above 65 % encourages mould and pest activity, RH below 45 % leads to desiccation, shrinking and cracking of organic materials.

The main challenge for architects, and heating, ventilation and air conditioning engineers is to create the most homogeneous controlled storage environment possible.

Philip Robinson                                                                                                       Rotronic UK

Humidity, Process

Sugar Production and Relative Humidity

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The sugar market worldwide

Sugar is one of the most important raw materials traded on the worldwide markets.

Top 5 sugar producing companies

1. Suedzucker AG,

2. Cosan SA Industria & Comercio

3. British Sugar PLC

4. Tereos Internacional SA

5. Mitr Phol Sugar Corp.

In the 18th century only a few countries were producing sugar. However, these days over 100 nations process different base materials into sucrose. Remarkably India, China, Brazil & the European Union alone deliver 50% of the global demand.

Sugar Facts:

– Worldwide 170 million tons of raw sugar were produced in 2011/2012

– Brazil, India, China & EU are the most important sugar producing nations

– With an annual consumption of more than 24 million tons India, is the world’s largest market for raw sugar

Raw materials & processing

In temperate regions such as West, Central & Eastern Europe, the United States, China and Japan raw sugar is produced from sugar beet. However in the tropics and subtropics sugar is extracted from sugar cane.

800px-cut_sugarcane

Sugar cane & Sugar Beet

Processing

The processing of these two raw materials only differs in the first few steps. The main goal is to extract the juice, containing the sugar,  as efficiently as possible.

Extracting the sugar

Sugar cane is cut into small pieces during the harvest. It is then put through an industrial press to squeeze out the sweet sap.
Sugar beet has to be processed in extraction towers, where the plants release their sugar during a hot water treatment at 70°C.

Evaporation

After filtering the juice the water is extracted by passing through different stages of evaporators until only a thick syrup is left consisting of around 70% sugar.

Crystallisation

The syrup is then boiled until sugar crystals are formed. These crystals are then cleaned through centrifugation. To further improve purity this process is repeated twice.

Cooling & drying

Now the sugar has to be dried. One option is in large scale drum dryers at a temperature of 60°C. after drying, the sugar is cooled down on fluidized-bed coolers before heading to the warehouse or packed for shipping.

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Inside a drum dryer.

Storage & logistics

Sugar belongs to the group of hygroscopic goods with an extremely low water content – below 1.5%. Basically sugar is a robust material but vulnerable to high humidity and temperature changes.
Generally it is recommended to store and transport sugar at a temperature of 20-25°C and 25-60% relative humidity.

By taking a closer look at the adsorption curve of sugar it is easy to see that over a long range of relative humidity the product quality is not affected. But as soon as the humidity level rises to 75% sugar starts to clump and above 80% relative humidity even dissolves .

Storage

Immediately after production the refined sugar is stored in humidity controlled sugar terminals or ventilated silos connected to dehumidifiers.

6.2.4. Sugar Terminal 5086

Sugar in a storage terminal

Logistics

Large quantities are trans-ported in silo trucks or train wagons. When sent by ship sugar is packed in double-walled bags made of natural fibre and plastic. If sealed like this, temperature is the crucial parameter which can affect the quality of the sugar. Due to big differences in temperature water vapour left inside the bags may cause clumping and even liquefaction.
The finer the sugar, the higher the risk of clumping.

Caking-dark-brown-sugar

Sugar clumping

Why the need to measure humidity?

As seen above, temperature and humidity measurements are crucial parameters in the sugar industry. Due to its hygroscopic behavior sugar can resist small changes in humidity, and slight temperature variations are not a major problem. But as soon as relative humidity rises above 80% or temperature changes significantly, the product can be destroyed as it clumps or even turns liquid.
During the process of evaporation, crystallisation, drying and cooling temperature and humidity play a huge role.

Philip Robinson                                                                                                        Rotronic UK

 

CO2, Humidity, News

Greenhouses and environmental control

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The idea of growing plants in environmentally controlled areas has existed since Roman times. The emperor Tiberius ate a cucumber-like vegetable daily. The Roman gardeners used artificial methods (similar to the greenhouse system) of growing to have the vegetable available on his table every day of the year.

The next step from the conventional greenhouse as we know it today will be the introduction of “vertical farms”. Currently, sophisticated so called “plantscrapers“ are being planned or are already under construction in Sweden, Japan, China, Singapore and the United States.

Skyscraper

Skyscraper farming might yet be a possible answer to the question of how to feed the nine billion people that are expected by the middle of the century. These types of green-houses have a tightly con-trolled level of temperature, humidity & CO2, sophisticated watering systems and in addition to sunlight, advanced artificial LED lighting that is specifically designed and installed for each plant family. This way, the crops grow much faster and very efficiently all year round. It is estimated, that the Swedish plantscraper that is planned to be 54m high, will produce thousands of tonnes of food a year, enough to feed up to 30,000 people.

Facts & figures:

  • Tomato is the second most important commercial vegetable crop after potato. Current world production is about 100 million tonnes produced on 3.7 million hectares.
  • In the year 2000, per capita consumption of fresh tomatoes in the U.S. was 17.8 lb,/ 8.73 kg.
  • About 85 percent of the world’s soybeans are processed, or “crushed,” annually into soybean meal and oil. Around 98 percent of the soybean meal that is crushed is further processed into animal feed.
  • The Food and Agriculture Organization of the United Nations (FAO) reports that world production of carrots and turnips (these plants are combined by the FAO for reporting purposes) for calendar year 2011 was almost 35,658 million tonnes.

Why do we need to measure humidity?

Greenhouse humidity levels are important both in prevent-ing plant diseases and promot-ing healthy and strong plant growth. High humidity can promote Botrytis and other fungal diseases. High humidity also restricts plant transpira-tion, which in turn limits evapo-rative leaf cooling and can lead to overheating of plant foliage. If high humidity persists for a long time, the restriction of transpiration can limit the “transpiration stream” of nutrients and can lead to nutrient deficiencies.

Low humidity levels are best avoided because these may increase foliar transpiration to the extent that the root system cannot keep up. Humidity is perhaps the most difficult of the greenhouse conditions to control. Most growers simply aim to avoid the extremes of humidity. Over most temperature ranges, a greenhouse humidity of 50 – 85 %rh is generally safe. Low humidity can be managed with the use of misters and foggers. It is also useful to shade plants under conditions of low humidity to reduce the rate of transpiration.

Transpiring plants add water vapour to the greenhouse air, increasing the humidity inside the greenhouse. Therefore, managing high humidity starts with ventilation control. Replacing warmer, humid greenhouse air with cooler, drier external air. Ventilation also involves significant energy losses, and therefore ventilation must often be accompanied by heating. Therefore, lowering greenhouse humidity with a combination of ventilation and heating increases energy costs significantly.

Candice 
Area Sales Manager