Digital Re-print - January | February 2014

Design of an efficient intake pit dedusting system the state-of-the-art in technology

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Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2014 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872

Innovations for a better world.

Built by feed millers for feed millers. Equipped with the industry‘s most efficient

drive system, the new Bühler pellet mill Kubex™ T saves up to 30% of energy –

while boosting line capacity to up to 80 tons per hour. With the Kubex™ T

you save costs, reduce the release of CO2 and make your operation even more

productive. Gaining competitive advantages has never been easier. For more in-

formation please visit www.buhlergroup.com/kubex-t

Bühler AG, Feed & Biomass, CH-9240 Uzwil, Switzerland, T +41 71 955 11 11, F +41 71 955 28 96

fu.buz@buhlergroup.com, www.buhlergroup.com

Visit us at Victam 2014 in Bangkok

8 - 10 April 2014, booth A071

VICTAMAsia2014FIAAP

A s i a 2014

2014grapas

asia

DPEF_210x297_KubexT_plant.indd 1 15.11.2013 14:09:58

The unloading of bulk materials such as cereals into intake pits is general-ly associated with considerable dust

emissions. The reasons for the need for an efficient receiving pit dust control system can be diverse. They range from reducing dust emmissions in neighboring residen-tial areas to improving health and safety at work for those working on site and the imperative requirement of prevent-ing serious damage to plant and danger of fatal injury from dust explosions.

Bühler Grain Logistics offers a choice between two systems, depending on applica-tion requirements: namely central or distrib-uted receiving pit dust control. These can be further subdivided on the basis of whether extraction is above or below the grid iron. Both systems are of modular design and can therefore be customized to the specific conditions of each situation.

To ensure that the required aspiration capacity of the intake pit dedusting is kept

to the minimum, every component needs to be optimized. It is therefore an advantage if there are gates at the entrance area which are kept closed at all times during unload-ing so that undesired air draughts and dust escaping to the surrounds can be prevented at the outset. For an optimum air flow inside the reception area, the upper section of the side wall is fitted with louvers. This prevents dust getting whirled up and ensures that the dust which collects is directed towards the extractors (Figure 1).

Another technical step towards minimis-ing dust emissions can be taken by installing a dust barrier. The barrier has dust retention panels (Figure 2) and prevents dust whirling up in the hopper. Practical experience from day-to-day operations has shown that up to 75 percent of the dust which is generated is produced when the bulk material hits the floor of the hopper. The dust barrier reduces air requirements, allows smaller filters and fans and cuts the power requirements of the fans by approximately 60 percent.

Filters for intake pits (decentralized)

For operations such as grain collection facilities or farms where the amount of dust generated is insignificant or plays only a minor role at most, decentralized dedusting is the more appropriate solution (Figure 3). In this case two adjustable inlet openings allow the air which requires cleaning to flow into the filter panels, from which it is directed to the fan through a manifold pipe line. The filter modules are connected using elements to form a single unit and the cleaned dust falls back into the reception pit via a diagonal plate.

Centralized intake pit dedusting

Centralized dedusting is designed more for food processors such as grain mills and producers of pasta, where removing dust from the raw product is essential. As in decentralized dedusting, the air to be cleaned is also caught by an aspiration panel. The individual aspiration modules are screwed together, which means that a variety of intake hopper sizes can be created ranging from 4 m to a maximum of 24 m in length. The aspiration panel is connected to a dust manifold pipe line which leads to a Bühler round filter. The round filter is a central filter with a jet-pulse cleaning system. This is where the flow of raw gas which is picked up and the dust which is retained are separated. The dust is conveyed through dust discharge chutes to separate dust con-tainers or big bags. As a result, the undesired dust no longer comes into contact with the product, thereby ensuring improved hygiene and greater safety. This system could be described as a form of initial pre-cleaning.

FilterTA-Luft directive requirements under

the German Federal Immissions Control Act stipulate emission limits of 20 milligrams of residual dust per normal cubic meter of air. The use of antistatic filter bags is one way of ensuring compliance with these reference values. They are more effective at cleaning than filter cells and also permit higher airto cloth ratios.

Design of an efficient intake pit dedusting system the state-of-the-art in technology

by Andreas Rembeck and Rico Hindemith, Bühler GmbH

Figure 1: Schematic diagram of an intake pit

16 | January - February 2014 Grain&Feed millinG technoloGyF

Innovations for a better world.

Built by feed millers for feed millers. Equipped with the industry‘s most efficient

drive system, the new Bühler pellet mill Kubex™ T saves up to 30% of energy –

while boosting line capacity to up to 80 tons per hour. With the Kubex™ T

you save costs, reduce the release of CO2 and make your operation even more

productive. Gaining competitive advantages has never been easier. For more in-

formation please visit www.buhlergroup.com/kubex-t

Bühler AG, Feed & Biomass, CH-9240 Uzwil, Switzerland, T +41 71 955 11 11, F +41 71 955 28 96

fu.buz@buhlergroup.com, www.buhlergroup.com

Visit us at Victam 2014 in Bangkok

8 - 10 April 2014, booth A071

VICTAMAsia2014FIAAP

A s i a 2014

2014grapas

asia

DPEF_210x297_KubexT_plant.indd 1 15.11.2013 14:09:58

Cleaning is on a time-controlled and/or differential pressure controlled basis, which ensures optimum filter performance and saves energy.

ComparisonThe two types of intake pit dedusting

systems can be designed for both side and rear unloading. With their adjustable double gap they can be customized to local conditions and are capable of aspiring even if the intake pit is overfilled. Depending on requirements the walls can be supplied with filter modules only or with partition walls as well, enabling sizes ranging from 2x3 to 4x24 square meters.

The differences between the two fil-ter systems are as follows: whereas the decentral dedusting system has a larger surface and therefore a lower filter load than the central dust removal system, the maximum dischargeable air rate of 55 m³ per minute and meter of pit length with a filter load of 5 m³ per minute and m² of filter surface (grain) is less than the dischargeable air rate of the central solu-tion, which is a maximum of 65 m³ per minute and meter of pit length for the same filter load.

Separate dust separation means that the central version requires more space for Bühler round filters (Figure 4) and

dust containers. On the other hand the decentralized dedusting system involves additional costs in terms of compressed air for cleaning the filter bags.

The purchase costs of the central receiving pit dedusting system are gen-erally higher than for a decentralized system because the former has more components. In terms of operating costs, however, the central solution normally works out better. Both systems have their advantages. The decision as to whether preference should be given to the central or decentral option depends on the spe-cific application.

www.buhlergroup.com

About BühlerBühler is a global technology leader

which specializes in the supply of equip-ment, systems and services for the con-version of renewable resources derived from food and synthetic substances into top quality functional products and materials. Bühler operates in over 140 countries and has some 10,000 employees worldwide. In fiscal 2012, the Group generated sales revenue of CHF 2,409 million.

Figure 3. Filters for intake pits (decentralized) Figure 4: Type RB round filter

Figure 2: Dust retention panels

17 | January - February 2014 Grain&Feed millinG technoloGy17 | January - February 2014 Grain&Feed millinG technoloGy F

Cleaning is on a time-controlled and/or differential pressure controlled basis, which ensures optimum filter performance and saves energy.

ComparisonThe two types of intake pit dedusting

systems can be designed for both side and rear unloading. With their adjustable double gap they can be customized to local conditions and are capable of aspiring even if the intake pit is overfilled. Depending on requirements the walls can be supplied with filter modules only or with partition walls as well, enabling sizes ranging from 2x3 to 4x24 square meters.

The differences between the two fil-ter systems are as follows: whereas the decentral dedusting system has a larger surface and therefore a lower filter load than the central dust removal system, the maximum dischargeable air rate of 55 m³ per minute and meter of pit length with a filter load of 5 m³ per minute and m² of filter surface (grain) is less than the dischargeable air rate of the central solu-tion, which is a maximum of 65 m³ per minute and meter of pit length for the same filter load.

Separate dust separation means that the central version requires more space for Bühler round filters (Figure 4) and

dust containers. On the other hand the decentralized dedusting system involves additional costs in terms of compressed air for cleaning the filter bags.

The purchase costs of the central receiving pit dedusting system are gen-erally higher than for a decentralized system because the former has more components. In terms of operating costs, however, the central solution normally works out better. Both systems have their advantages. The decision as to whether preference should be given to the central or decentral option depends on the spe-cific application.

www.buhlergroup.com

About BühlerBühler is a global technology leader

which specializes in the supply of equip-ment, systems and services for the con-version of renewable resources derived from food and synthetic substances into top quality functional products and materials. Bühler operates in over 140 countries and has some 10,000 employees worldwide. In fiscal 2012, the Group generated sales revenue of CHF 2,409 million.

Figure 3. Filters for intake pits (decentralized) Figure 4: Type RB round filter

Figure 2: Dust retention panels

17 | January - February 2014 Grain&Feed millinG technoloGy17 | January - February 2014 Grain&Feed millinG technoloGy F

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• Having no choice is not reasonable The quest for a healthier snack

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• Design of an efficient intake pit dedusting system the state-of-the-art in technology

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