If a bakery has to deal with a quantity of approx. 20 tons of flour every day, this huge amount can only be accomplished at a fully automated large-scale business, where the flour is conveyed all-automatic. Regarding the wholesale bakery Sehne in Ehningen, near Böblingen the efficiency of the former pneumatic conveying system had been exhausted up to the limit. Therefore, a considerable capacity increase had become inevitable. The solution put into practise by the end of 2007 is brilliant and convincing: An additional pneumatic conveying unit together with a new integrated weighing station had been added to the present conveying unit between the external silos and the former weighing station. Thanks to the almost complete further use of all components of the former solution and the additional insertion of the new unit, it was possible to establish an especially economic and reliable new transport- and weighing concept with considerably increased number of cycles. The extra demand of conveying air is produced by two additional positive displacement blowers manufactured by Aerzener Maschinenfabrik.
First started with a bakery in Ehningen founded in 1957 by master baker Heinrich Sehne and his wife Ruth, a huge company has developed with a staff of almost 800 employees. The second-generation guided family company produces on an area of 10.000 m and offers a variety of more than 200 different bakeries. An own truck fleet with 40 vehicles supplies the products to 140 own sales outlets within a radius of approx. 50 km around the location of Ehningen. Originally the full-automatic weighing station at Sehne consisted of two independently working balances, which had been provided by the six external silos via a pneumatic conveying unit. However, due to the constantly increasing flour consumption pretty soon this system had worked at its limits, so that a new solution with a considerably higher capacity had been mandatory. Then, Messrs. Georg Stein Process Equipment in 49324 Melle developed a new transport- and weighing concept. Owner Georg Stein recommended an additional “inserted” pneumatic conveying unit with an additional, more efficient weighing station under further use of the former unit components as far as possible. This proposal had been planned after preliminary talks and had been commissioned at the end of 2007.
Messrs. Georg Stein Process Equipment supplies individual process solutions regarding raw material handling, mechanical and thermal process engineering for the foodstuff- and chemical industry. The focus is on the pneumatic and mechanical conveying- and aspiration units for the safe and efficient disposal of dust at production units. Each established unit is adjusted company-related and customized to the production courses and room conditions of each customer, as the design and technical properties and condition must always refer to the individual requirements at site. This includes the distances to be bypassed, the required flow rates, the quantity of parts-removal and receiving stations and last but not least the features of the bulk goods. This has also applied for the new solution in the wholesale bakery Sehne in Ehningen.
Decisive participation in all fully automatic-working conveying- and weighing procedures within the new pneumatic conveying concept near Sehne provides a superordinated control concept. It was designed and delivered by Messrs. AWS Automation (24783 Osterrönfeld, near Rendsburg) – a long-time partner of Messrs. Sehne in the field of electrical and electronical control- and switch gears. The AWS-system works fully automatic and multifunctional, is visualized via screen and called up in the production according to the stipulations of the central control room and is controlled via the AWS software fully automatically. The control concept for the entire unit can be telemonitored in addition by AWS from the location of Osterrönfeld. The AWS-system controls fully automatically all formulations for more than 200 products of the company and is also responsible for the constant daily high quality of all Sehne-products. Messrs. AWS Automation has worked as general contractor regarding this project. Messrs. Georg Stein Process Equipment has been responsible for the entire “hardware”.
The new weighing concept
Regarding the old concept the flour of the six silos had been transported pneumatically by two blowers via two piping with intermediate switch points directly to the former weighing station with two scales. In order to increase the transport capacity an additional pneumatic conveying unit was installed with a new, more efficient weighing station between the external silos and the old weighing stations. This insertion consists of two completely autarkicly working individual units. They are supplied with the necessary conveying air by two new positive displacement blowers of Aerzener Maschinenfabrik. The weighing procedure of the component parts taken off the storage silos is now being carried out exclusively in the two new weighing stations of this “inserted” new pneumatic conveying unit. The two scales of the old weighing station still only work as target reservoir and register the entries of the charges. The mixture of flour and its further processing is then carried out in different production steps according to stipulations.
Main component parts of each single station regarding the inserted weighing station are the main scale and two reservoirs switched in addition, being also equipped as scales. The system works as follows: Three of the six external silos are drained as usual by the two conveying air blowers already available. Now, the flour is no longer transported to the old scales, but is led to the inserted weighing station via sieving machines. By means of monitored switch points the flour reaches then the main scale pre-selected by a computer program, to be portioned afterwards. Via an electro-pneumatically monitored folding box the portioned amount enters fully automatically one of the two subsequent reservoirs arranged below. These reservoirs are also designed as scales (main scale I with subsequent reservoirs A und B, main scale II with subsequent reservoirs C and D). Due to the connecting drain of the filled-in following reservoir, a new weighing procedure starts with the main scale. However, the weighed amount of flour enters the second subsequent reservoir. In the meantime, a new weighing procedure has started with the main scale and following drain into the first subsequent reservoir. This weighing cycle of the main scale with follow-on two-way drain into two subsequent reservoirs continues constantly.
Pneumatic transport
The conveying air necessary for the pneumatic transport of the weighed flour quantities is produced by two new conveyed air blowers of Aerzener Maschinenfabrik. They supply each one of the two conveying lanes of the new piping system, from the new weighing station to the former weighing station. The four subsequent reservoirs of the new weighing station (main scale I with subsequent reservoir A and B, main scale II with subsequent reservoir C and D) are connected staggered to each one conveying lane of this new piping system (subsequent reservoir A and C to conveying lane I, subsequent reservoir B and D to conveying lane II). Upon request, the allocation of the compressed-air blowers to these subsequent reservoir couples can be monitored by a pneumatically automatic switch-point system. (Note: The compressed-air necessary for the control of these switch points had been produced by separate compressed-air supply system and supplied to the users via separate system). The flour penetrating from the subsequent reservoirs into the piping system is then led via the conveying air of the new Aerzen positive displacement blowers to the old weighing station, which represents only the destination with registration function. Thanks to this cycle concept the weighing- and transport procedures run at tremendous speed and practically without any delay times. In addition the new solution offers a sufficient reserve performance, so that during the next development phase, it is possible to carry out two or even four additional weighing procedures without extensive additional modifications. Due to the new ”inserted” pneumatic conveying system, this new concept leads to a considerable increase of the weighing rating, so that the flour supply of Sehne corresponds again to the increased requirements of the production. The entire system works at low-pressure range and is aligned for delta p = 1000 mbar max.
Thanks to the availability of two new Aerzen conveyed air blowers as well as the present switches and shut-off flaps in the new piping system the allocation of the conveyed air blowers can be switched to the two conveying lines upon requirement. However, according to procedure the remaining blower cannot serve both conveying lines at the same time, but only one exactly defined conveying line. Therefore, the standstill of a conveyed air blower means a considerable reduction of the total capacity of the concept, even that the new weighing system has been designed continuously redundant.
Aerzen positive displacement blower units
As producer of the conveying air required in addition for the new solution of Sehne, Mr. Georg Stein has selected Aerzen positive displacement blower units of type GM 10 S of series “DELTA BLOWER Generation 5”. Aerzener Maschinenfabrik has manufactured positive displacement blowers since 1868. Therefore, Aerzen is one of the oldest and biggest manufacturers of such machines worldwide and has market leading position in Europe. The new blower generation “DELTA BLOWER Generation 5” combines the well-known and successful characteristics of the former generation with new technical innovations, meeting already today the future requirements. 5 main advantages of the new Generation 5 are in the front for the customer. At the same time they represent distinctive features of other blower models, such as:
• The decreased sound level by approx. 6 to 8 dB (A)
• The even easier installation, operation and maintenance (service package with lifting jack, funnel and initial oil filling; operation only from the front; easily accessible maintenance components; oil level control when machine is running by means of external oil sight glass
• The aeration without additional electric motor by mechanical fan on the blower shaft (regarding units with acoustic hood)
• The renunciation of sound-absorbing material (sound reduction by air deflection in the base support formed as discharge silencer);
• The reduction of the linear dimension with smaller units and the space-saving side-by-side installation with all models.
Further advantages are: The oil-free conveyance (sealing) thanks to the piston ring labyrinth sealing (proven over decades) in connection with neutral chambers (open to atmosphere), Aerzen base support certified as spark extinguisher for ATEX applications, the blower stage with patented procedure for pulsation decrease, the standardized application of energy-sufficient motors of classes EFF1, the authorization as per PED-guideline (discharge silencer and pressure valve), regarding encapsulated units the intake on the “cold” side of the unit, the drive via high-performance narrow V-belts and the automatic belt re-tension by hinged motor mounting plate.
Georg Stein does not only appreciate the brand awareness: “The machines made by Aerzener Maschinenfabrik are also famous in the foodstuff industry because of their high reliability. Therefore, they are first choice by plant manufacturers and users. In addition, I appreciate the short official channels of this manufacturer, so that in special situations very quick reactions and solutions have always been possible. As plant manufacturer I am liable towards my customers for the entire project. This also applies for the conveyed air units – the core of each project. Therefore, I choose for my projects only sub-suppliers who are reliable for 100%. I expect this also from the overnight service for spare part orders. By experience, I am always on the safe side with Aerzen.”
Two DELTA BLOWER blowers of new “Generation 5”
The alignment of the required blowers (at Sehne) (pressure, design etc.) has been carried out depending on the case of requirement by Messrs. Georg Stein Process Equipment. Two Aerzen positive displacement blower units of type GM 10 S, series ”DELTA BLOWER Generation 5” had been installed. An ATEX design had not been necessary in this case. Aerzen units are designed for a conveyed capacity of 9.000 kg flour each / per hour. They work at a constant performance. At present, the blowers produce at an overpressure of approx. 600 mbar. However, they can be driven by an increase of the drive capacity up to an overpressure of 1000 mbar. Following a detailed planning, the transition from the old to the new concept had been carried out during company holidays at a week-end in December 2007. Starting the working shift on Sunday night the new concept has already been in good working condition. In case of system failures Messrs. Sehne contacts at first the general contractor AWS. Looking at the remote control room installed by AWS, there are first clues about the cause of failure and the malfunctioning area. Thanks to the prompt agreement with Messrs. Georg Stein Process Equipment, the further procedure has been coordinated between both partners without any time loss, so that the cause of malfunction can be eliminated as quickly as possible.
Sehne is absolutely satisfied with the results. “The new basic concept has worked from the very beginning. Since its commissioning at the end of 2007 the unit has been operated without any malfunction. It has completely met our expectations. Thanks to the concept realized by Messrs. Georg Stein Equipment, we could optimally adjust the required number of cycles of the weighing procedures to the considerably increased requirements of our production. Essential share in the success of this concept have the two new positive displacement blowers of Aerzener Maschinenfabrik. It has been quite pleasing that we could accomplish the new concept under further use at large extent concerning the present units with clear investment costs”, emphasizes co-owner Gerd Sehne.
Pneumatic Conveying of Flour
PNEUMATIC CONVEYING OF POWDERY GOODS
by Stephan Brand
Aerzener Maschinenfabrik GmbH
31855 Aerzen, Germany
03.08.2009
If a bakery has to deal with a quantity of approx. 20 tons of flour every day, this huge amount can only be accomplished at a fully automated large-scale business, where the flour is conveyed all-automatic. Regarding the wholesale bakery Sehne in Ehningen, near Böblingen the efficiency of the former pneumatic conveying system had been exhausted up to the limit. Therefore, a considerable capacity increase had become inevitable. The solution put into practise by the end of 2007 is brilliant and convincing: An additional pneumatic conveying unit together with a new integrated weighing station had been added to the present conveying unit between the external silos and the former weighing station. Thanks to the almost complete further use of all components of the former solution and the additional insertion of the new unit, it was possible to establish an especially economic and reliable new transport- and weighing concept with considerably increased number of cycles. The extra demand of conveying air is produced by two additional positive displacement blowers manufactured by Aerzener Maschinenfabrik.
First started with a bakery in Ehningen founded in 1957 by master baker Heinrich Sehne and his wife Ruth, a huge company has developed with a staff of almost 800 employees. The second-generation guided family company produces on an area of 10.000 m and offers a variety of more than 200 different bakeries. An own truck fleet with 40 vehicles supplies the products to 140 own sales outlets within a radius of approx. 50 km around the location of Ehningen. Originally the full-automatic weighing station at Sehne consisted of two independently working balances, which had been provided by the six external silos via a pneumatic conveying unit. However, due to the constantly increasing flour consumption pretty soon this system had worked at its limits, so that a new solution with a considerably higher capacity had been mandatory. Then, Messrs. Georg Stein Process Equipment in 49324 Melle developed a new transport- and weighing concept. Owner Georg Stein recommended an additional “inserted” pneumatic conveying unit with an additional, more efficient weighing station under further use of the former unit components as far as possible. This proposal had been planned after preliminary talks and had been commissioned at the end of 2007.
Messrs. Georg Stein Process Equipment supplies individual process solutions regarding raw material handling, mechanical and thermal process engineering for the foodstuff- and chemical industry. The focus is on the pneumatic and mechanical conveying- and aspiration units for the safe and efficient disposal of dust at production units. Each established unit is adjusted company-related and customized to the production courses and room conditions of each customer, as the design and technical properties and condition must always refer to the individual requirements at site. This includes the distances to be bypassed, the required flow rates, the quantity of parts-removal and receiving stations and last but not least the features of the bulk goods. This has also applied for the new solution in the wholesale bakery Sehne in Ehningen.
Decisive participation in all fully automatic-working conveying- and weighing procedures within the new pneumatic conveying concept near Sehne provides a superordinated control concept. It was designed and delivered by Messrs. AWS Automation (24783 Osterrönfeld, near Rendsburg) – a long-time partner of Messrs. Sehne in the field of electrical and electronical control- and switch gears. The AWS-system works fully automatic and multifunctional, is visualized via screen and called up in the production according to the stipulations of the central control room and is controlled via the AWS software fully automatically. The control concept for the entire unit can be telemonitored in addition by AWS from the location of Osterrönfeld. The AWS-system controls fully automatically all formulations for more than 200 products of the company and is also responsible for the constant daily high quality of all Sehne-products. Messrs. AWS Automation has worked as general contractor regarding this project. Messrs. Georg Stein Process Equipment has been responsible for the entire “hardware”.
The new weighing concept
Regarding the old concept the flour of the six silos had been transported pneumatically by two blowers via two piping with intermediate switch points directly to the former weighing station with two scales. In order to increase the transport capacity an additional pneumatic conveying unit was installed with a new, more efficient weighing station between the external silos and the old weighing stations. This insertion consists of two completely autarkicly working individual units. They are supplied with the necessary conveying air by two new positive displacement blowers of Aerzener Maschinenfabrik. The weighing procedure of the component parts taken off the storage silos is now being carried out exclusively in the two new weighing stations of this “inserted” new pneumatic conveying unit. The two scales of the old weighing station still only work as target reservoir and register the entries of the charges. The mixture of flour and its further processing is then carried out in different production steps according to stipulations.
Main component parts of each single station regarding the inserted weighing station are the main scale and two reservoirs switched in addition, being also equipped as scales. The system works as follows: Three of the six external silos are drained as usual by the two conveying air blowers already available. Now, the flour is no longer transported to the old scales, but is led to the inserted weighing station via sieving machines. By means of monitored switch points the flour reaches then the main scale pre-selected by a computer program, to be portioned afterwards. Via an electro-pneumatically monitored folding box the portioned amount enters fully automatically one of the two subsequent reservoirs arranged below. These reservoirs are also designed as scales (main scale I with subsequent reservoirs A und B, main scale II with subsequent reservoirs C and D). Due to the connecting drain of the filled-in following reservoir, a new weighing procedure starts with the main scale. However, the weighed amount of flour enters the second subsequent reservoir. In the meantime, a new weighing procedure has started with the main scale and following drain into the first subsequent reservoir. This weighing cycle of the main scale with follow-on two-way drain into two subsequent reservoirs continues constantly.
Pneumatic transport
The conveying air necessary for the pneumatic transport of the weighed flour quantities is produced by two new conveyed air blowers of Aerzener Maschinenfabrik. They supply each one of the two conveying lanes of the new piping system, from the new weighing station to the former weighing station. The four subsequent reservoirs of the new weighing station (main scale I with subsequent reservoir A and B, main scale II with subsequent reservoir C and D) are connected staggered to each one conveying lane of this new piping system (subsequent reservoir A and C to conveying lane I, subsequent reservoir B and D to conveying lane II). Upon request, the allocation of the compressed-air blowers to these subsequent reservoir couples can be monitored by a pneumatically automatic switch-point system. (Note: The compressed-air necessary for the control of these switch points had been produced by separate compressed-air supply system and supplied to the users via separate system). The flour penetrating from the subsequent reservoirs into the piping system is then led via the conveying air of the new Aerzen positive displacement blowers to the old weighing station, which represents only the destination with registration function. Thanks to this cycle concept the weighing- and transport procedures run at tremendous speed and practically without any delay times. In addition the new solution offers a sufficient reserve performance, so that during the next development phase, it is possible to carry out two or even four additional weighing procedures without extensive additional modifications. Due to the new ”inserted” pneumatic conveying system, this new concept leads to a considerable increase of the weighing rating, so that the flour supply of Sehne corresponds again to the increased requirements of the production. The entire system works at low-pressure range and is aligned for delta p = 1000 mbar max.
Thanks to the availability of two new Aerzen conveyed air blowers as well as the present switches and shut-off flaps in the new piping system the allocation of the conveyed air blowers can be switched to the two conveying lines upon requirement. However, according to procedure the remaining blower cannot serve both conveying lines at the same time, but only one exactly defined conveying line. Therefore, the standstill of a conveyed air blower means a considerable reduction of the total capacity of the concept, even that the new weighing system has been designed continuously redundant.
Aerzen positive displacement blower units
As producer of the conveying air required in addition for the new solution of Sehne, Mr. Georg Stein has selected Aerzen positive displacement blower units of type GM 10 S of series “DELTA BLOWER Generation 5”. Aerzener Maschinenfabrik has manufactured positive displacement blowers since 1868. Therefore, Aerzen is one of the oldest and biggest manufacturers of such machines worldwide and has market leading position in Europe. The new blower generation “DELTA BLOWER Generation 5” combines the well-known and successful characteristics of the former generation with new technical innovations, meeting already today the future requirements. 5 main advantages of the new Generation 5 are in the front for the customer. At the same time they represent distinctive features of other blower models, such as:
• The decreased sound level by approx. 6 to 8 dB (A)
• The even easier installation, operation and maintenance (service package with lifting jack, funnel and initial oil filling; operation only from the front; easily accessible maintenance components; oil level control when machine is running by means of external oil sight glass
• The aeration without additional electric motor by mechanical fan on the blower shaft (regarding units with acoustic hood)
• The renunciation of sound-absorbing material (sound reduction by air deflection in the base support formed as discharge silencer);
• The reduction of the linear dimension with smaller units and the space-saving side-by-side installation with all models.
Further advantages are: The oil-free conveyance (sealing) thanks to the piston ring labyrinth sealing (proven over decades) in connection with neutral chambers (open to atmosphere), Aerzen base support certified as spark extinguisher for ATEX applications, the blower stage with patented procedure for pulsation decrease, the standardized application of energy-sufficient motors of classes EFF1, the authorization as per PED-guideline (discharge silencer and pressure valve), regarding encapsulated units the intake on the “cold” side of the unit, the drive via high-performance narrow V-belts and the automatic belt re-tension by hinged motor mounting plate.
Georg Stein does not only appreciate the brand awareness: “The machines made by Aerzener Maschinenfabrik are also famous in the foodstuff industry because of their high reliability. Therefore, they are first choice by plant manufacturers and users. In addition, I appreciate the short official channels of this manufacturer, so that in special situations very quick reactions and solutions have always been possible. As plant manufacturer I am liable towards my customers for the entire project. This also applies for the conveyed air units – the core of each project. Therefore, I choose for my projects only sub-suppliers who are reliable for 100%. I expect this also from the overnight service for spare part orders. By experience, I am always on the safe side with Aerzen.”
Two DELTA BLOWER blowers of new “Generation 5”
The alignment of the required blowers (at Sehne) (pressure, design etc.) has been carried out depending on the case of requirement by Messrs. Georg Stein Process Equipment. Two Aerzen positive displacement blower units of type GM 10 S, series ”DELTA BLOWER Generation 5” had been installed. An ATEX design had not been necessary in this case. Aerzen units are designed for a conveyed capacity of 9.000 kg flour each / per hour. They work at a constant performance. At present, the blowers produce at an overpressure of approx. 600 mbar. However, they can be driven by an increase of the drive capacity up to an overpressure of 1000 mbar. Following a detailed planning, the transition from the old to the new concept had been carried out during company holidays at a week-end in December 2007. Starting the working shift on Sunday night the new concept has already been in good working condition. In case of system failures Messrs. Sehne contacts at first the general contractor AWS. Looking at the remote control room installed by AWS, there are first clues about the cause of failure and the malfunctioning area. Thanks to the prompt agreement with Messrs. Georg Stein Process Equipment, the further procedure has been coordinated between both partners without any time loss, so that the cause of malfunction can be eliminated as quickly as possible.
Sehne is absolutely satisfied with the results. “The new basic concept has worked from the very beginning. Since its commissioning at the end of 2007 the unit has been operated without any malfunction. It has completely met our expectations. Thanks to the concept realized by Messrs. Georg Stein Equipment, we could optimally adjust the required number of cycles of the weighing procedures to the considerably increased requirements of our production. Essential share in the success of this concept have the two new positive displacement blowers of Aerzener Maschinenfabrik. It has been quite pleasing that we could accomplish the new concept under further use at large extent concerning the present units with clear investment costs”, emphasizes co-owner Gerd Sehne.
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