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Silos - Bulk storage special



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									                   Digital Re-print -
               January | February 2014
                      Silos - Bulk storage special

Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom.
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or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872


           SILO DESIGN AND
      by Bentall Rowlands Storage Systems Limited, UK

          torage systems must be individu-           capitalise on the expanding market in storage         build the best relationships with our customers
          ally designed for each client. Each        systems.”                                             and spend time making sure that they receive
          project must have a bespoke design             With capabilities to design, manufacture,         the best possible service from the initial design
    that ensures it matches, if not exceeds          supply and install storage systems from               concepts through to installation and comple-
    client expectations,” says Kevin Groom,          an extensive range of products, Bentall               tion of the project,” adds Mr Groom.
    technical director of Bentall Rowlands           Rowlands provides a comprehensive end-to-
    Storage Systems Limited in the UK.               end solution which can be designed to any             Seismic activity
                                                     specific requirement.                                     “When we are tasked with the job of
        “We are extremely proud of the projects          As the demand for bulk storage and                designing a new storage facility, there has to
    that we have undertaken in geographically        handling equipment increases worldwide,               be a thorough inspection and survey of the
    challenged areas, proving that whatever the      volumes and competitive pricing in grain              site done prior to any work taking place.
    specification, we are sure to provide the        handling charges require efficient solutions.             “The geology of the area is key to the
    most suitable design necessary.                  We manufacture the right quality of product           design. For example we were chosen to
        “We have designed and installed silos        to produce the efficiency savings required to         design a site in New Zealand.
    worldwide in countries that include the UK,      justify the investment.                                   “This country is known for its volcanic
    Kenya, Thailand, Holland, France, Ukraine,           Each project undertaken is designed dif-          activity, earthquakes and geothermal areas
    Malawi, New Zealand and many more.               ferently and will need to take into account           because of its position on the boundary of
        With over a century of experience in         a number of factors. This includes geo-               the Australian Plate and Pacific Plates. We
    the design, quality and installation of grain    graphical issues, including large temperature         needed to know the area in great detail
    storage systems, Bentall Rowlands have           fluctuations, seismic activity, high winds and        to make sure we designed the size and
    developed new technologies that have been        corrosion.                                            structure of the silos accordingly to dismiss
    applied to the manufacture as well as the                                                              any chances of collapse or damage if seismic
    installation of grain storage and processing     Why do silos fail?                                    activity does occur.
    equipment.                                           On a number of occasions, the failure                 “When designing a storage system for
        Bentall Rowlands is a leading UK manu-       may only involve distortion or deformation,           erection in a known earthquake region, they
    facturer in complete storage and processing      which doesn’t necessarily pose an immediate           must be designed to the countries relevant
    equipment solutions for the agricultural and     safety hazard.                                        seismic standards. All silos will need to be
    industrial markets.                                  On the other hand, failure can mean               built a great deal stronger to cater for the
        It offers a wide range of galvanised steel   complete collapse of the structure resulting          horizontal loading at ground level. It is far
    silos, flat bottom and hopper bottom, water      in the loss of use and in some cases, the             better to keep the silos height down.
    tanks, catwalks and platforms, material han-     loss of life.                                             “Silos that are shorter and wider are far
    dling equipment, cleaning and grading and            The major causes of these failures are            better than those that are tall and thin. When
    weighing and drying systems that can be          predominately down to design errors, con-             seismic activity strikes, a structure that has a
    assembled worldwide.                             struction errors and utilisation errors.              larger base area is more likely to withstand
        “Our engineering and technical expertise         “It is important that silos are built to meet     the pressures and remain intact. If you have
    combined with continued focus on customer        the specifications set out in the design, eliminat-   a taller and thinner structure, this presents a
    satisfaction places us in a strong position to   ing any chance of silo failure. We work hard to       huge amount of stress to the lower sections

                           grain silos                           hoppered silos

                                                              tech expo                     Grain
Lucknow. 1 - 2 February                           Kiev. 11 - 13 February          El Cairo. 18 - 20 February

O ces and Factory:
Ctra. de Arenas km. 2,300
13210 Villarta de San Juan • Ciudad Real- Spain
T: +34 926 640 475 • F: +34 926 640 294
Madrid O ce:
C/ Azcona, 37 • 28028 Madrid - Spain
T: +34 91 726 43 04 • F: +34 91 361 15 94
 20 | January - February 2014                                                                                   Grain  &Feed millinG technoloGy
                                                                                                        uct will affect the design of the silo, as does
                                                                                                        the moisture content of the stored product.
                                                                                                            “We look at the bulk solid that is being
                                                                                                        stored, and take into account the levels
                                                                                                        of moisture. Increased moisture within a
                                                                                                        storage system will affect the grain, causing
                                                                                                        expansion within the silo.”
                                                                                                            If this occurs when the materials are
                                                                                                        not being taken out, upward expansion is
                                                                                                        restrained. This means that the majority of
                                                                                                        the expansion will occur in the horizontal
                                                                                                        direction, resulting in increased lateral pres-
                                                                                                        sure, and hoop stresses in the silo walls.
                                                                                                            “In situations like this, we have to assess
                                                                                                        the area and the likelihood of significant
                                                                                                        moisture migration as this will affect the
                                                                                                        design of the system.
of the silo which will ultimately result in the   to withstand gusts of 50m per second, which               Our silo roofs are designed with an area
collapse of this structure.                       equates to 180km per hour.                            of overhang, meaning that in areas where
    “Due to the fact that the magnitude               “During the recent storms that occurred           rainfall will be a potential problem, we have
of earthquakes varies greatly, all our silos      in the North of England and Scotland, we              that ‘run-off’ effect from the roof that pro-
are individually designed to suit each areas      had reports that all of the silos withstood the       tects the grain within the silos.
requirement.                                      gale force winds, with no reported problems               “If our storage systems were designed
    “The contract was originally built for the    or damage.”                                           differently, it would result in added moisture
New Zealand Government to store oil seed              In areas where silos could be prone to these      content within the silo, causing expansion
rape. The stored grain would then be sent         high winds, the structure needs to be quite           and increased hoop stresses, but also the
for crushing to be turned into biofuel. The       similar to that where seismic activity takes place.   danger of losing the grain to mould.”
silos were designed to hold the wet oil seed      Silos will withstand these huge wind speeds
rape prior to going through a continuous          when they are designed to cover a greater base        The need for galvanising
flow drier,” he says.                             area. This gives them the stability needed to            Galvanisation is the process of applying
                                                  remain intact once a storm has passed.                a protective coating of zinc to the silos in
Dealing with high winds                                                                                 order to prevent rusting occurring.
    High winds can cause great problems for       Temperature change                                       In areas where high levels of corrosion
a number of structures, including our storage        For countries that are prone to tempera-           could be present, this is a necessity.
facilities.                                       ture fluctuations, the design of the storage             “Compared to other companies, we use
    “We make sure that our silos are designed     system needs to be carefully thought out.             G600 as a standard whereas some compa-
                                                                              More so for               nies may only use G90. This greatly increases
                                                                          countries prone to            the life expectancy of our silos.”
                                                                          high levels of mois-             For example, in tropical marine areas
                                                                          ture. In severe cold          where storage systems are required, you
                                                                          weather        where          can expect them to last somewhere around
                                                                          snow can be quite             35 years which is a huge advantage over
                                                                          extreme, it is the            other companies. Countries that have high
                                                                          roof of the structure         levels of precipitation and humidity will rely
                                                                          that needs to be one          on the galvanising of the silos in order to
                                                                          of the main focuses.          protect them from this corrosion. This is
                                                                              Snow load is the          standard on all types of storage equipment,
                                                                          reason for engineer-          to add that extra bit of security on life
                                                                          ing changes.                  expectancy.
                                                                              When design-
                                                                          ing the roof, it is           Getting the shipments right
                                                                          important to know                 “Not only do we have to take into
                                                                          what depth of snow            account the design of the silos in these geo-
                                                                          can be expected in a          graphically challenged areas, but the vast job
                                                                          given area.                   of sorting the logistical side out.
                                                                              “We designed                  “All our shipments have to be correct at
                                                                          a bespoke storage             all times, especially the ones going to these
                                                                          system for an area            challenged areas.”
                                                                          within the Ukraine                Getting it right first time is imperative.
                                                                          where the snow can                “To start shipping missing goods is not
                                                                          get extremely deep.           only a logistical nightmare, but can be
                                                                              “We specifically          a very expensive mishap, extremely time
                                                                          designed the roof             consuming and can hold up the project by a
                                                                          on each silo to be            significant amount of time.
                                                                          able to withstand a               “At Bentall Rowlands, when building large
                                                                          pressure of 1kn/m2            grain stores, it is common to agree a spares
                                                                          which equates to              package that can be shipped with the main
                                                                          one meter of snow,”           contract. More likely than not, some of the
                                                                          he adds.                      parts may become damaged or misplaced
                                                                              Temperature               and parts that may only cost a few pounds
                                                                          changes within the            could cost thousands if it has to be air
                                                                          actual stored prod-           freighted,” he notes.

           by Pablo Fernández , Southeast Asia Area Manager Silos Cordoba

        toring soybean and soybean meal              material can then be used first as opposed to       Table 1: Moisture content and safe storage
        leads to specific storage problems.          long-term storage within the original stock.        durations
        That is why we need to know more                Soybean meal is difficult to handle
                                                                                                             Moisture        Safe storage period
    about them.                                      because of its poor flowability and bridging
                                                                                                            content, %     Market          Seed
                                                     characteristics. Soybean meal tends to settle
                                                                                                             wet basis      stock          stock
        For example, the structure of the bean       or consolidate over time. This phenom-
    impacts its handling and:                        enon occurs in most granular materials and
                                                                                                                10-11     4 years         1 year
      • Handling involves conveying and              becomes more severe with increased mois-
         transporting from the farm to end-          ture, time and when particle sizes are small.            10-12,5    1-3 years       6 months
         user. During this phase there are many                                                                            6-9            Poor
         different movements from harvest to         Flow characteristcs                                        13-14
                                                                                                                          months       germination
         the production into oil and meal               The flow characteristics of bulk materials
      • The structure of a soybean seed makes        are dependent on individual particle shape,                14-15    6 months
         it susceptible to splitting and breakage    density, frictional property and moisture con-
         during mechanical handling. The             tent. Granular materials have three typical flow   storability. By focusing on these three ele-
         extent of breakage in soybeans during       patterns during discharge from hopper bottom       ments, we can assure the perfect storage of
         conveying varies with the impact force      bins: normal discharge pattern (there is no        soya bean and soya bean meal:
         imposed on each individual seed. The        problem here), bridging and funneling. These
         least breakage occurs when soybeans         two latter problems occur in grains containing     Moisture content:
         are conveyed in a bucket elevator as        high content of foreign material or moisture.          Depending on the percentage of mois-
         compared to other conveying methods            Typical flow problems of meal products          ture, the periods of storage change. Soybeans
        Figure 1 shows the extent of soya bean       discharged from storage silos are hang-ups,        contain moisture ranging from 12 percent to
    breakage with four methods of conveying:         dead pocket and piping (see figure 2).             15 percent at harvest time. Above 13 per-
    the first one represents the percentage of          These are usually due to a combination          cent should be dried to reduce the risk of
    breakage of the grain in a free fall of 30, 21   of factors such as poor hopper design, high        deterioration due to seed respiration, mold
    and 12 meters.                                   moisture content and storage time.                 attack, spontaneous heating and reduced
        The storability of soybeans is affected                                                         germination.
    by the degree of damage to the seed coat         External factors
    and by other factors such as mold or insect          Beside all of the above soybean and soy-       Temperature:
    attack. It is therefore important to inspect     bean meal consideration, we have to keep              Temperature is another very impor-
    soybeans for mechanical and other forms of       in mind the most important external factors:       tant factor influencing in soybean storage.
    damage prior to storage.                         moisture content, temperature and duration         Growth of fungi and chemical changes, such
        If the amount of broken or split soybeans    of temperature.                                    as oxidation, increased with temperature in
    is very high, it may be prudent to separate          The general condition of the product and       both meal and whole beans.
    the broken or split grains by sieving. This      amount of foreign materials also affect its           Moreover, it is really important to con-
The right storage solution starts with the right advice.

Storage decisions can affect your operation for decades. That’s why so many companies around the world trust Westeel with
their storage needs. Not only do we supply some of the most advanced storage products available, we support our products
with the expert project leadership and sound engineering advice necessary to ensure that the decisions you make today
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                                                                                                                            14WEST5242-0214 | Canada (Home Office) 204-233-7133 | United States 701-280-2467 | Spain +34 91 216 14 97
F    24 | January - February 2014                                                                                  Grain  &Feed millinG technoloGy
                                                                                                           by stack burning (charring) or at worst, the
                         BREAKAGE IN SOYBEANS
                                                                                            Figure 1       entire facility will be lost through fire.
     PERCENT BREAKAGE                                                                                          Aerating soybeans when fire has already
                                                                                                           started makes the situation worse. A temper-
                                                                                                           ature monitoring system in soybean storage
                                                                                                           silos is essential. Immediate corrective meas-
                                                                                                           ures for heating cannot be over-emphasised.

                                                                                                           Change in color and general
                           30m         21m       12m     SPOUT          THROW            ELEV              appearance:
                        HANDLING METHOD                                                                        In general, sound soybeans are plump
                                                                                                           with bright uniform tan with no trace of
                                                                                                           green colour and free from unusual spots
       TYPICAL PROBLEMS WITH MEAL PRODUCTS                                                  Figure 2       and shriveled appearance.
                                                                                                               Discoloured soybeans usually indicate
                                                                                                           inferior quality and lower market value.
                                                                                                           The change in colour is usually associated
                                                                                                           with mold invasion accompanied by micro-
                                                                                                           bial respiration and subsequent heating. This
                                                                                                           deterioration process can be detected by
                                                                                                           periodic drawing of samples from the silos
                                                                                                           as part of an integrated approach of quality
                                                                                                               Once detected, appropriate measures
                                                                                                           can then be taken such as cooling the grain
                                                                                                           either by aeration or use of a portable
                                                                                                           cooling unit. Another corrective measure
                                                                                                           is to transfer the grain to another silo thus
                                                                                                           breaking any hot spots present and cooling
                                                                                                           the soybeans during the conveying process.
                                                                                                               However, this should be done only as a
                                                                                                           last resort since it is costly and will increase
                                                                                                           the amount of broken or split soybean seed.
                           HANG UPS             DEAD POCKETS                      PIPING
                                                                                                           Mustiness and off-odor condition:
                                                                                                              Musty odor usually indicates an advanced
                                                                                                           stage of insect or mold infestation and
                                                                                                           should be dealt with immediately. If this is
                                                                                                           detected, the soybean should be aerated to
                                                                                                           remove the bad odor and cool the material.
                                                                                                              Seeds should then be used at the earliest
                                                                                                           opportunity. The grain should be fumigated
                                                                                                           immediately if insects are present. A sharp
                                                                                                           odor may indicate rancidity due to chemical
                                                                                                           changes in the oil component.

                                                                                                            Lumping and caking:
    sider the climate in the different regions         fine foreign materials and through pockets of           Lumping and caking indicate a very
    of the world. Experience indicates that            high concentration of large foreign materials.      advanced stage of fungi invasion in soybeans
    under hot and humid tropical conditions,               This condition creates a non-uniform            and soybean meal. In metal bins, caking usually
    grains stored in metal bins exhibit sweat-         flow of air during aeration, thus, making it        occurs on the bin walls as a result of sweating
    ing. This problem arises with extreme high         an ineffective operation. Hence, cleaning           or moisture condensing on the inner surface
    temperatures reached on the inner surface          soybeans prior to storage will minimise the         of the cold bin wall. The condensing moisture
    of the metal silo on a hot day, then, at           risk of spoilage and economic loss.                 is absorbed by the adjacent grains resulting in
    night, the rapid cooling of the metal results                                                          either sprouting or mold growth.
    in moisture condensation as the dew point          Detecting possible problems
    is reached.                                           Here you have some indicators that will          Useful tips for soybean and
        Caking and charring in metal silos can be      help you to detect any possible problems            soybean meal storage
    attributed to this phenomenon. Installing the      with the products storage inside the silos.             For all of this, low product moisture, low
    proper devices of ventilation and cooling                                                              temperature and short storage periods are
    machines keep the correct temperature and          Heating:                                            desirable. After this brief analysis we can
    avoid these problems.                                  Heating is the most common indicator            give some tips for those who need to store
                                                       of a problem in stored grains and oilseeds.         either soybean meal or soya bean:
    Time of storage:                                       High grain temperatures normally indi-              The proper devices for storing soybean
        Shorter better! Fine foreign materials         cate either microbial or insect activity. If left   and soybean meal are:
    tend to segregate during bin loading and           unchecked, this may lead to heat-damaged              1. Hydraulic sweep auger (for soybean
    occupy void spaces in the central region of        or charred grains due to the phenomenon                  meal). This sweep auger effectively
    the grain mass.                                    of stack burning. Because of this danger, hot            reclaims meal products from silos
        Meanwhile the large and lighter materials      spots in stored soybeans must be cooled or               because it is able to work with full silos.
    will accumulate close to the walls of the          dissipated before they reach the critical level.         One full rotation of the screw once
    silo. Then, during aeration, the air will flow         If no action is taken when heating in soy-           a day is mandatory to prevent the
    around spots with a higher concentration of        beans occurs, either the product will be lost            mentioned discharge problems.
F   26 | January - February 2014                                                                                          Grain &Feed millinG technoloGy
    2. Smoother wall ring+washer outside                  soybean for a few days to prevent spoilage          storing soybean meal? In order to avoid
       the silos and head-round bolts inside              before proper drying. It should be noted            long storage in soymeal silos, we of course
       the silos. Different silos manufacturers           that aeration is not intended to dry grains.        recommend our model:
       using different wall ring waves. We have        6. Cooling machines. Strongly recommended                  Silo model: 12.22/12
       to be careful and choose a long wave.              in tropical climates with high heat and high            Silo diameter: 12.22m
    3. Pre-cleaner. “Fine foreign materials               humidity. Soybean, even after harvested,                Eave height: 13.73m
       tend to segregate during bin loading and           still keeps on breathing.                               Total capacity: 1.749m3 (1120T)
       occupy void spaces in the central region           The grain once chilled, keeps its low                   Discharge capacity: 50T/h approx
       of the grain mass. Meanwhile the large             temperature for a long time, without the                Please note that few silos in the same site
       and lighter materials will accumulate              need for a continuous cooling. Direct               can share the same hydraulic unit, and there-
       close to the walls silos”.                         consequences of non-controlled storing              fore the unitary price decreases. With several
       That fact effects the ventilation,                 of wet grain are the appearance of fungi            silos they can rotate the product between
       “the air will flow around spots with               and toxins, which are very dangerous                them; that is especially useful for long storage.
       higher concentration of fine foreign               for the health of humans and animals.
       materials and through pockets of high              The proper storing of grain by means                What extraction screws do you
       concentration of large foreign materials.          of chilled and dry air fix completely or            deliver together with above flat
       This condition will create a non-uniform           widely minimise the problem.                        bottom silos?
       flow of air during aeration, thus, making       7. Temperature monitoring system. This                    We have worked with hydraulic sweep
       it an ineffective operation.” Cleaning the         device is essential to control and correct          augers from Morillon. According to the
       product prior to storage will minimise             any deviation of the optimum.                       capacity required they can be single arm or
       the risk of spoilage and economic loss.         8. Belt conveyors. To prevent the                      double arm.
       Moreover, if the product has to be                 breakage of the grain. This kind of
       dried it is totally necessary to avoid the         conveyor can move grains for great                  What hopper silos are suitable for
       burn of the waste (fine foreign materials          distances without damage.                           storing soybean meal?
       like straw, dust, etc) inside the dryer.        9. Periodic drawing of product samples                     Due to the poor flow characteristics of
    4. Dryer. Soybean moisture above 13                   and accurately testing them.                        the soy, hopper silos with a reinforced cone
       percent should be dried to reduce                 By following all these steps you can be              of 60º are suitable. These silos should be
       the risk of deterioration due to seed         assured of avoiding change in color, risk of             equipped with screw discharge conveyors
       respiration, mold attack, spontaneous         deterioration due to seed respiration, mold              The biggest hopper silo model we have
       heating and reduced germination.              attack, spontaneous heating, reduced germi-              installed so far for this product is our model
    5. Ventilation. Centrifugal fans. The primary    nation, mustiness and off-odor conditions,               60º hopper silo 6.88/9, with the 467m3.
       purpose of aeration is to make the            presence of insects, lumping and caking and
       temperature of the grain bulk uniform. This   finally economic loss.
       prevents moisture migration in the grain                                                                  More      inforMation:
       mass due to natural convection. Aeration      Answering your questions                              
       may also be used to hold partially dried         What flat bottom silos are suitable for

                          STORAGE SYSTEMS WORLDWIDE

          We take looking after
           grain very seriously

                          Stand No. D109
                        Hall EH104 and EH103

                                                                        Bentall Rowlands Storage Systems Limited
                                                                        Dragonby Vale Enterprise Park, Mannaberg Way, Scunthorpe, North Lincolnshire, DN15 8XF, UK
                                                                        T: +44 (0)1724 282 828 E: W:
                                                                                       SITE 3

                                                                                                                 SITE 4

                                                                                                                                             SITE 5

                                                                                                                                                                     SITE 6
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                                                             SITE 2
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