Factory Organisation PLANT L。eATl。N The location of the dehydration factory must be considered very carefully, because, whereas at one time proximity to the source of raw materials was of paramount importance, availability of an adequate labour force and the provision for effluent disposal will, perhaps, constitute a more pressing requirement A rural environment is obviously better than a location in a highly industrialised area, because operation involves the utilisation of a considerable amount of open space for the rec materials, particularly where vegetable dehydration is being undertaken This chapter, in dealing with factory planning, proceeds on the premise that vegetables are the principal raw material to be processed Fruit dehydration is dealt with in Chapter 7 On the assumption that the labour availability factor has been resolved, and co-operation from the Local authority on effluent disposal has been secured, it is important that the location should be a focal point for the intake of indigenous raw material within a radius of some 80 kilometres. In the case of highly perishable vegetables, such as vined peas and green beans, availability should be within half that radius. These figures are relevant where the scale of ope s an intake of 70-80 tons of produce per day, which is, in effect, a viable level upon which to work. This would be regarded as a medium size plant Production on a larger scale would call for a wider area of raw material
2 Facto ry 0 rgan i sat io n PLANT LOCATION The location of the dehydration factory must be considered very carefully, because, whereas at one time proximity to the source of raw materials was of paramount importance, availability of an adequate labour force and the provision for effluent disposal will, perhaps, constitute a more pressing requirement. A rural environment is obviously better than a location in a highly industrialised area, because the operation involves the utilisation of a considerable amount of open space for the reception and storage of raw materials, particularly where vegetable dehydration is being undertaken. This chapter, in dealing with factory planning, proceeds on the premise that vegetables are the principal raw material to be processed. Fruit dehydration is dealt with in Chapter 7. On the assumption that the labour availability factor has been resolved, and co-operation from the Local Authority on effluent disposal has been secured, it is important that the location should be a focal point for the intake of indigenous raw material within a radius of some 80 kilome-. In the case of highly perishable vegetables, such as vined peas and green beans, availability should be within half that radius. These figures are relevant where the scale of operation presupposes an average intake of 70-80 tons of produce per day which is, in effect, a viable level upon which to work. This would be regarded as a medium size plant. Production on a larger scale would call for a wider area of raw material 21
availability but, in the ensuing chapters, it is intended to concentrate on the problems of the medium size operator, coming into the industry for the first time, or developing into dehydration from some other food processing activity. It is, perhaps, more likely, at this stage of the growth of dehydration, that development in Europe will be at this sort of level, rather than at that applying in the US, where plants with an intake capability of upwards of 500 tons a day are not uncommon RAW MATERIAL Once the vegetable programme has been established, an efficient procurement system is an absolute necessity, as it is vital that the plant be fed with a round-the-clock supply of raw material for many months of the year, with no hiatus or short-fall due to weather conditions, or any other circumstances. Binding contracts must be made with reliable growers to ensure this and also to ensure that suitable varieties of vegetable-ones that lend themselves favourably to the process-are grown. Random purchasing on the open market is a system not to be relied upon by the dehydrator, because wherever the price is right the variety will be wrong, and vice versa The one exception, when this procedure is varied, is in the case of potatoes, and spot purchases are often made as the season proceeds. Whilst there is an element of risk in this particularly in a of low solids and a short crop- potato prices tend to be more stable than those for some other crops, and availability is spread over a much longer period fro.? some particular potato products, however, do call for speclalvarieties as a first choice. Potato granules and flakes, for example, should be made igh starch content tubers and, if these types are not grown in the traditional growing areas, special plantings under contract may have to be made adjacent to the plant location. On the other hand, some processors find that, to meet a cost problem with some potato products, they have to process culls from ware(table grade)potatoes, and, in this case, contracting is not usually possible. Grading stations can usually supply large quantities of this material, which is satisfactory for the manufacture of some grades of dehydrated product, and long term arrangements can always be made for intake from such sources, provided certain basic quality requirements are covered Contracts The procurement contract with the grower can take one of two forms, either: (1)A contract wherein the purchaser undertakes to buy from the vendor a specific tonnage of vegetables at a fixed price per ton, delivered to the factory over a specified period, or (2)a contract wherein the purchaser
availability but, in the ensuing chapters, it is intended to concentrate on the problems of the medium size operator, coming into the industry for the first time, or developing into dehydration from some other food processing activity. It is, perhaps, more likely, at this stage of the growth of dehydration, that development in Europe will be at this sort of level, rather than at that applying in the US, where plants with an intake capability of upwards of 500 tons a day are not uncommon. RAW MATERIAL Once the vegetable programme has been established, an efficient procurement system is an absolute necessity, as it is vital that the plant be fed with a round-the-clock supply of raw material for many months of the year, with no hiatus or short-fall due to weather conditions, or any other circumstances. Binding contracts must be made with reliable growers to ensure this and also to ensure that suitable varieties of vegetable - ones that lend themselves favourably to the process -are grown. Random purchasing on the open market is a system not to be relied upon by the dehydrator, because wherever the price is right the variety will be wrong, and vice versa. The one exception, when this procedure is varied, is in the case of potatoes, and spot purchases are often made as the season proceeds. Whilst there is an element of risk in this particularly in a Season of low solids and a short crop - potato prices tend to be more stable than those for some other crops, and availability is spread over a much longer period. Some particular potato products, however, do call for special varieties as a first choice. Potato granules and flakes, for example, should be made from high starch content tubers and, if these types am not grown in the traditional growing areas, special plantings under contract may have to be made adjacent to the plant location. On the other hand, some processors find that, to meet a cost problem with some potato products, they have to process culls from ware (table grade) potatoes, and, in this case, contracting is not usually possible. Grading stations can usually supply large quantities of this material, which is satisfactory for the manufacture of some grades of dehydrated pmduct, and long term arrangements can always be made for intake from such sources, provided certain basic quality requirements are covered. Contracts The procurement contract with the grower can take one of two forms, either: (I) A contract wherein the purchaser undertakes to buy from the vendor a specific tonnage of vegetables at a fixed price per ton, delivered to the factory over a specified period, or (2) a contract wherein the purchaser 22
undertakes to buy the produce of a specific acreage laid down by the vendor, at an agreed price per acre In the first instance, the grower must cover all contingencies arising from total or partial crop failure, and carry a not inconsiderable element of risk of the purchaser buying in against him in the event of a crop failure The second form of contract implies that the processor takes over some of this risk but, in return, has a reasonable chance of buying his product cheaper, if he has an efficient fieldsman service to supervise the grower and ensure a high level of good husbandry. cases, the processor will elect to supply the seed at arieties and, in some The contract, in whichever form, will specify agreed cost to the grower. Further stipulations will cover the quality standard, the rate of intake r day and the period over which intake will be accepted. The contract will also state whether the produce is to be delivered in bulk, or in containers and how accepted weights will be established. There is invariably provision for arbitration in the event of a dispute. It is important that the quality clause in the contract should be most specific, so that the grower is made aware of the standard of grading or dressing required. The processor will also underline his right to oversee, through his fieldsmen, the sowing, planting, cultivation and harvesting of the crop Supervision must also be exercised with types of fertilise weedicide and pesticide used in connection with the cultivation, as dangerous residuals can sometimes affect the produce at maturity. All these factors must be fully considered and covered in the document but, as this procurement procedure has been adopted for many years by canners and freezers, and has equally been accepted by growers, either individually or by their Associations, where group negotiations arise, the dehydrator shoul not really have any difficulty in getting all the above clauses implemented LAB。 UR REQUIREMENTS In selecting a site for the factory, the consideration of suitable labour availability will have been made. On the assumption that the location is rural, certain advantages as to quality of labour are usually apparent, in that both male and female operatives who have agricultural backgrounds and traditions often integrate very satisfactorily into vegetable processing as this is, in effect, an extension of their way of life The labour content of the putative 70-80 ton per day plant will vary according to the type of drying plant selected and the range of products to be handled but some guide can be given if certain assumptions are made at this point. Let it be supposed that the operation is mounted on a ten months
undertakes to buy the produce of a specific acreage laid down by the vendor, at an agreed price per acre. In the first instance, the grower must cover all contingencies arising from total or partial crop failure, and carry a not inconsiderable element of risk of the purchaser buying in against him in the event of a crop failure. The second form of contract implies that the processor takes over some of this risk but, in return, has a reasonable chance of buying his product cheaper, if he has an efficient fieldsman service to supervise the grower and ensure a high level of good husbandry. The contract, in whichever form, will specify varieties and, in some cases, the processor will elect to supply the seed at an agreed cost to the grower. Further stipulations will cover the quality standard, the rate of intake per day and the period over which intake will be accepted. The contract will also state whether the produce is to be delivered in bulk, or in containers and how accepted weights will be established. There is invariably provision for arbitration in the event of a dispute. It is important that the quality clause in the contract should be most specific, so that the grower is made aware of the standard of grading or dressing required. The processor will also underline his right to oversee, through his fieldsmen, the sowing, planting, cultivation and harvesting of the crop. Supervision must also be exercised with types of fertiliser, weedicide and pesticide used in connection with the cultivation, as dangerous residuals can sometimes affect the pduce at maturity. All these factors must be fully considered and covered in the document but, as this procurement procedure has been adopted for many years by canners and freezers, and has equally been accepted by growers, either individually or by their Associations, where group negotiations arise, the dehydrator should not really have any difficulty in getting all the above clauses implemented. LABOUR REQUIREMENTS In selecting a site for the factory, the consideration of suitable labour availability will have been made. On the assumption that the location is rural, certain advantages as to quality of labour are usually apparent, in that both male and female operatives who have agricultural backgrounds and traditions often integrate very satisfactorily into vegetable processing as this is, in effect, an extension of their way of life. The labour content of the putative 70-80 ton per day plant will vary according to the type of drying plant selected and the range of products to be handled but some guide can be given if certain assumptions are made at this point. Let it be supposed that the operation is mounted on a ten months’ 23
programme over the following range of vegetables: peas, green beans, potatoes (granules and cubes), cabbage, leeks, carrots, celery, beetroot and The process staff will require to operate on a three shift system, usually ix days per week, with a plant cleaning shift and a maintenance shift in addition at the weekend. Local custom may require that this system be covered by four teams to avoid excessive overtime at weekends but it is by o means uncommon in some factories for staff to accept this overtime, the three eight hour shifts being covered by three teams changing their shifts by rota every week. The many types of dehydration plant will be considered in detail in the following chapters but, for the purpose of assessing the process labour ontent of a typical medium size plant, it could be assumed that the following dryers would be required to handle the above ten month programme For Granules: an Air-Lift dryer with a capacity of 1.5 tons of raw potatoes per hour For peas, green beans, cabbage, celery and leeks one Hot Air Through Conveyor Band Dryer, with a capacity of up to 3 tons of prepared raw egetables per hour-the capacity will vary according to the type of vegetable and size of cut For root vegetables and potato cubes: one Hot Air Through Conveyo Band Dryer with the same capacity as mentioned for other vegetables These dryers would not be operating concurrently throughout the whole of the season but would come into operation in accordance with the availability of the crops. It is vitally important that at certain times some excess drying capacity is available to cope with gluts, or a dryer breakdown, hence the advisability of duplicating the band dryer. Some important crops, which have a short harvest period, such as peas and French beans, can overlap and, in these circumstances, shortage of drying capacity can have dire cor appn The process labour to man this scale of operation, per shift,would be ly as fol Shift Superintendent: 1 Forewomen Quality Control Male Plant Operators: 10 2(maintenance duties only) Electrician 1(maintenance duties only)
programme over the following range of vegetables: peas, green beans, potatoes (granules and cubes), cabbage, leeks, camts, celery, beetroot and turnips. The process staff will require to operate on a three shift system, usually six days per week, with a plant cleaning shift and a maintenance shift in addition at the weekend. Local custom may require that this system be covered by four teams to avoid excessive overtime at weekends but it is by no means uncommon in some factories for staff to accept this overtime, the three eight hour shifts being covered by three teams changing their shifts by rota every week. The many types of dehydration plant will be considered in detail in the following chapters but, for the purpose of assessing the process labour content of a typical medium size plant, it could be assumed that the following dryers would be required to handle the above ten month programme: For Granules: an Air-Lift dryer with a capacity of 1.5 tons of raw potatoes per hour; For peas, green beans, cabbage, celery and leeks one Hot Air Through Conveyor Band Dryer, with a capacity of up to 3 tons of prepared m vegetables per hour- the capacity will vary according to the type of vegetable and size of cut; For mot vegetables and potato cubes: one Hot Air Through Conveyor Band Dryer with the same capacity as mentioned for other vegetables. These dryers would not be operating concurrently throughout the whole of the season but would come into operation in accordance with the availability of the crops. It is vitally important that at certain times some excess drying capacity is available to cope with gluts, or a dryer breakdown, hence the advisability of duplicating the band dryer. Some important crops, which have a short harvest period, such as peas and French beans, can overlap and, in these circumstances, shortage of drying capacity can have dire consequences. The process labour to man this scale of operation, per shift, would be approximately as follows: Shift Superintendent: 1 Foreman: 1 Forewomen: 1 Male Plant Operators: 10 Fitters: 2 (maintenance duties only) Electrician: 1 (maintenance duties only) Boilerman: 1 Quality Control: 2 24
30-50(trimming and selection) Permanent night men 15-25(Trimming and selection) The female labour content will vary according to the types of vegetable being processed. The above numbers in any case assume that, at the selection and packing end of the process, the products are being bulk packed. Where the product is intended for retail distribution in small units, a very much larger female packing staff would be required to operate filling and packing machinery. Such considerations, in this instance, however, have not been taken into account. Male operators will normally substitute for women on the 10pm to 6am shift It is stressed that the figures given can only be taken as a rough guide, d the of two types of dryer, the methods of operating which are efficient and particularly economical in labour content generally The conveyor band dryer, either single or multi pass, is probably more versatile than most in the types of vegetable it will handle, and it is particularly suitable for long sustained runs of one product. Its merits, along with those of other dryers, will be described in later chapters but in the context of the present plant under review, it requires a minimum of staff to operate it. As in the canning and freezing industries, the greatest concentration of female labour is in the trimming and selection departments, and unless strict control is exercised in these areas, as to the numbers and efficiency costs can easily overtake profits Technology has made great strides, however, in reducing the tedium and unrewarding work of product selection, and there are now very efficient colour sorting devices on the market, which effectively select and reject blemished material in the raw state, or after drying. This reduces the labour requirement for trimming and selection, and the development of these machines to the present peak of efficiency has cut the cost of these operations very considerably. As the particle size of dried vegetables rarely exceeds 10mm by 10mm by 10mm, the electronic colour sorter can scan these particles in their trajectory through an optical box against a predetermined coloured background. Any particle, whose colour, by reason of blemish, differs from that which is acceptable, is pushed into a different trajectory by a jet of compressed air and diverted through a waste spout. These machines have high efficiency and perform the task of selection at a fraction of the cost of hand labour Some visual inspection is still advisable after the product has passed
Women: 30-50 (trimming and selection) Permanent night men 15-25 (Trimming and selection) The female labour content will vary according to the types of vegetable being pmcessed. The above numbers in any case assume that, at the selection and packing end of the pmcess, the products e being bulk packed. Where the product is intended for retail distribution in small units, a very much larger female packing staff would be required to operate filling and packing machinery. Such considerations, in this instance, however, have not been taken into account. Male operators will normally substitute for women on the lOpm to 6am shift. It is stressed that the figures given can only be taken as a mugh guide, and they are based on the manning of two particular types of dryer, the methods of operating which are efficient and particularly economical in labour content generally. The conveyor band dryer, either single or multi pass, is probably more versatile than most in the types of vegetable it will handle, and it is particularly suitable for long sustained runs of one product. Its merits, along with those of other dryers, will be described in later chapters but in the context of the present plant under review, it requires a minimum of staff to operate it. As in the canning and freezing industries, the greatest concentration of female labour is in the trimming and selection departments, and unless strict control is exercised in these areas, as to the numbers and efficiency, costs can easily overtake profits. Technology has made great strides, however, in reducing the tedium and unrewarding work of product selection, and there are now very efficient colour sorting devices on the market, which effectively select and reject blemished material in the raw state, or after drying. This reduces the labour requirement for trimming and selection, and the development of these machines to the present peak of efficiency has cut the cost of these operations very considerably. As the particle size of dried vegetables rarely exceeds lOmm by lOmm by lOmm, the electronic colour sorter can scan these particles in their trajectory through an optical box against a predetermined coloured background. Any particle, whose colour, by reason of blemish, differs from that which is acceptable, is pushed into a different trajectory by a jet of compressed air and diverted through a waste spout. These machines have a high efficiency and perform the task of selection at a fraction of the cost of hand labour. Some visual inspection is still advisable after the product has passed 25
through a colour sorter but the labour content at this point is minimal Intake staff Very considerable labour economies can be effected in the vegetable intakedepartment by the use of bulk loaders forpotatoesand root vegetables, 500kg tanks for peas and large crates or tote boxes for cabbage, leeks, celery etc. Green beans are perhaps the only vegetable for which bags or nets need Also, the use of storagesilos for potatoes and roots reduces the intake staff to one, or two at most, per shift, and this staff can be used for fluming the raw material into the plant. This presupposes that an adequate supply o cheap water is available from an adjacentriver, waterway or borehole, fmm which the processor has a prescribed right to abstract water. This need not be potable water, as it is only used as a means of moving the vegetables fmm the silos through flumes into a primary washer, and thence into the preparation plant. Such water is normally discharged from the washer into settling tanks, to remove silt and stones washed off the vegetables, before being returned to waste or recycled. In some instances, it may have to go through an effluent treatment plant before it can be discharged but the loca Authority will have to be consulted on this matter. A destoning machine isa necessary adjunct to this part of thesystem. The shiftquality controller has an important part to play at this point, as it is his responsibility to ensure that the quality of the intake measures up Typical bax
through a colour sorter but the labour content at this point is minimal. Intake Staff Very considerable labour economies can be effected in the vegetable intake department by the use of bulk loaders for potatoes and root vegetables, 500kg tanks for peas and large crates or tote boxes for cabbage, leeks, celery, etc. Green beans are perhaps the only vegetable for which bags or nets need to be Also, the use of storage silos for potatoes and roots reduces the intake staff to one, or two at most, per shift, and this staff can be used for fluming the raw material into the plant. This presupposes that an adequate supply of cheap water is available from an adjacent river, waterway or borehole, fmm which the processor has a prescribed right to abstract water. This need not be potable water, as it is only used as a means of moving the vegetables fmm the silos through flumes into a primary washer, and thence into the preparation plant. Such water is normally discharged from the washer into settling tanks, to remove silt and stones washed off the vegetables, before being returned to waste or recycled. In some instances, it may have to go through an effluent treatment plant before it can be discharged but the Local Authority will have to be consulted on this matter. A destoning machine is a necessary adjunct to this part of the system. The shift quality controller has an important part to play at this point, as it is his responsibility to ensure that the quality of the intake measures up Typical box tipper 26
to the contractual requirements of the buying department Potatoes must be examined for total solids, reducing sugar content, excess soil, blemish and grading Vined peas are examined for quality and tested for temperature and tenderometer reading Carrots, cabbage, celery, leeks, etc, are checked for the standard of dressing which is called for in the Procurement contract. Extraneous matter in vegetables, apart from the waste factor, can also do untold damage to preparation plant later in the process, and intake staff must be very vigilant on this score The period of intake will normally extend over twelve hours of each day, except during the season when highly perishable vegetables, such as peas and beans, are being handled, then intake and quality control staff will be required round the clock on three shifts. Adequate staffing at this point is Warehousing Staff The staffing of the warehousing and despatch departments will depend, as to numbers, on the nature and size of the packs being produced. and whether a bulk or retail consumer trade is being carried on. If the factory is concerned mainly with bulk packs, two men per shift for stock movement will be adequate, with a daytime superintendent in overall charge Maintenance Staff A part from the fitting staff detailed to cover the shift maintenance duties, it is necessary to provide for an adequate day shift maintenance st in the field of both mechanical and electrical engineering. Dehydration plant, operating round the clock for many months of the year, demands a high standard of maintenance, 'and there is invariably a heavy day shift Programme of servicing equipment, both mechanical and electrical temporarily taken out of service for a major overhaul. a minimum of six day shift fitters and three electricians would be required for the size of undertaking under review. These are supplementary to maintenance personnel working on the three shift rota. A carpenter, painter and bricklayer can also be usefull ed all the year round on the day shift maintenance staff because continuous shift operation levies a heavy toll on the buildings, particularly at the wet preparation end of the factory Laboratory and Horticultural Staff Laboratory staff required, excluding the shift quality controllers, will be three as a minimum, depending on the range of products being handled The main duties in the laboratory are the routine analytical tests on the dried
to the contractual requirements of the buying department. Potatoes must be examined for total solids, reducing sugar content, excess soil, blemish and grading. Vined peas are examined for quality and tested for temperature and tenderometer reading. Camts, cabbage, celery, leeks, etc, are checked for the standard of dressing which is called for in the procurement contract. Extraneous matter in vegetables, apart from the waste factor, can also do untold damage to preparation plant later in the process, and intake staff must be very vigilant on this score. The period of intake will normally extend over twelve hours of each day, except during the season when highly perishable vegetables, such as peas and beans, are being handled, then intake and quality control staff will be required round the clock on three shifts. Adequate staffing at this point is, therefore, imperative. Warehousing Staff The staffing of the warehousing and despatch departments will depend, as to numbers, on the nature and size of the packs being produced, and whether a bulk or retail consumer trade is being carried on. If the factory is concerned mainly with bulk packs, two men per shift for stock movement will be adequate, with a daytime superintendent in overall charge. Maintenance Staff Apart from the fitting staff detailed to cover the shift maintenance duties, it is necessary to provide for an adequate day shift maintenance staff in the field of both mechanical and electrical engineering. Dehydration plant, operating round the clock for many months of the year, demands a high standard of maintenance,' and there is invariably a heavy day shift programme of servicing equipment, both mechanical and electrical, temporarily taken out of service for a major overhaul. A minimum of six day shift fitters and three electricians would be required for the size of undertaking under review. These are supplementary to maintenance personnel working on the three shift rota. A carpenter, painter and bricklayer can also be usefully employed all the year round on the day shift maintenance staff because continuous shift operation levies a heavy toll on the buildings, particularly at the wet preparation end of the factory. Laboratory and Horticultural Staff Laboratory staff quired, excluding the shift quality controllers, will be three as a minimum, depending on the range of products being handled. The main duties in the laboratory are the routine analytical tests on the dried 27
ised by a chief technician, assisted by more academically unqualified assistants. Some research and development will also be carried out by the senior staff. A horticultural officer and two fieldsmen are also required WATER For the size of plant under review, the requirements for water washing, process use, boilers, etc, but excluding any fluming operations, will be of the order of 8 million litres per week of eight hour shifts. temp The quality of the water is important, and it is necessary to know the temporary and permanent hardness characteristics. It may be that the local supply is not entirely suitable for every kind of vegetable to be processed and some treatment may be necessary For example, peas require soft water for washing and blanching, as high calcium content in the supply has a toughening effect on the skins. In these circumstances a water softening plant will need to be installed to treat the water which is in contact with the peas in process. Conversely, potatoes, particularly when used for cubing or slicing, require a higher degree hardness in the processing water, and it is usually necessary to treat this with calcium chloride in the blanching process. Ideal water conditions are, therefore, unlikely to be found in many locations, and perhaps a supply with 8 degrees of hardness might be regarded as a fair average, requiring less treatment overall than most samples. Consideration of the water analysis should, therefore, be treated of some importance when choosing the factory site. Boiler water should be reasonably soft, to avoid scale formation but where hard water conditions apply, the supply will have to be treated hemically, or a base exchange softening plant installed. With the latter, some further organic or chemical treatment will be necessary to correct excess alkalinity, which is a feature of the base exchange method It is good boilerhouse practice to return all the available condensate from the processing plant, ie, from dryer steam batteries, blancher and lye peeler steam coils and space heating batteries, back to the hot well in the boilerhouse, so that the feed water supply is available at a high temperature There are several points in the factory where mains water can be conserved by recycling, particularly the washing plant. Care must be exercised here, however to ensure that recycled water is not contaminated and some in-plant chlorination will be necessary to implement this recycling system
product, and these are supervised by a chief technician, assisted by two or more academically unqualified assistants. Some research and development will also be carried out by the senior staff. A horticultural officer and two fieldsmen are also required. WATER For the size of plant under review, the requirements for water washing, process use, boilers, etc, but excluding any fluming operations, will be of the order of 8 million litres per week of eight hour shifts. The quality of the water is important, and it is necessary to know the temporary and permanent hardness characteristics. It may be that the local supply is not entirely suitable for every kind of vegetable to be processed and some treatment may be necessary. For example, peas require soft water for washing and blanching, as a high calcium content in the supply has a toughening effect on the skins. In these circumstances a water softening plant will need to be installed to treat the water which is in contact with the peas in process. Conversely, potatoes, particularly when used for cubing or slicing, require a higher degree of hardness in the processing water, and it is usually necessary to treat this with calcium chloride in the blanching process. Ideal water conditions are, therefore, unlikely to be found in many locations, and perhaps a supply with 8 degrees of hardness might be regarded as a fair average, requiring less treatment overall than most samples. Consideration of the water analysis should, therefore, be treated as of some importance when choosing the factory site. Boiler water should be reasonably soft, to avoid scale formation but, where hard water conditions apply, the supply will have to be treated chemically, or a base exchange softening plant installed. With the latter, some further organic or chemical treatment will be necessary to correct excess alkalinity which is a feature of the base exchange method. It is good boilerhouse practice to =turn all the available condensate from the processing plant, ie, from dryer steam batteries, blancher and lye peeler steam coils and space heating batteries, back to the hot well in the boilerhouse, so that the feed water supply is available at a high temperature. There are several points in the factory where mains water can be conserved by recycling, particularly the washing plant. Care must be exercised here, however, to ensure that recycled water is not contaminated, and some in-plant chlorination willbe necessary to implement this recycling system. 28
Fumin a che Fluming water, as referred to earlier, must come from a free or, at least, ap source. It is not viable to use mains water for this purpose, as the volume required for fluming, say 70-80 tons of root vegetables or potatoes per twentyfour hour day, will be of the order of 1.2 million litres. It therefore, desirable that the factory be situated near a river, or waterway, and that the River authority can be persuaded to give the necessary licence to abstract water for this particular purpose. An alternative to this source of supply is, of course, a borehole, or a series of boreholes capable of that sort of capacity. The sugar beet factories use this system of fluming beet into their plants, some thousands of tons per day being moved from silo to process by high pressure water jets, with a minimum amount of manual effort. It is a system well worth emulating in the dehydration factory, where large quantities of roots and potatoes have to be handled End elevation of root vegetable silo with centre fluming channel Silos The construction of the silos is quite a simple matter and a typical size for a 100 ton unit would be 30m by 4m. The side walls are 1m in height and constructed of 23cm thick masonry. Both ends of the silo are left allow incoming bulk loaders or tipper lorries to discharge their loads. The concrete bottom of the silo slopes from either side wall to the fluming channel in the middle. This runs longitudinally down the whole length of the silo with a fall of 50cm in the 30m length. The width of the channel is 30cm, and this is rebated to take 7. 5cm thick timber cover boards which are fitted flush with the sloping silo bottom. The shallowest point of the flume channel must be not less than 15cm deeP, and it is from here that the water supply is introduced from powerful centrifugal Pumps with a capacity of 91,000 to 136,000 litres per hour. The cover boards are removed in that part of the silo which requires to be emptied, and the vegetables feed in a steady stream into the fluming channel, whence they are carried along with the flow of
Fluming Fluming water, as referred to earlier, must come from a free or, at least, a cheap source. It is not viable to use mains water for this purpose, as the volume required for fluming, say 70-80 tons of root vegetables or potatoes per twentyfour hour day, will be of the order of 1.2 million lihes. It is, thefore, desirable that the factory be situated near a river, or waterway, and that the River Authority can be persuaded to give the necessary licence to abstract water for this particular purpose. An alternative to this sourre of supply is, of course, a borehole, or a series of boreholes capable of that sort of capacity. The sugar beet factories use this system of fluming beet into their plants, some thousands of tons per day being moved from silo to process by high pressure water jets, with a minimum amount of manual effort. It is a system well worth emulating in the dehydration factory, where large quantities of roots and potatoes have to be handled. /.--.-- AI7 r’ I, --___. I.,//;*/, / -v7Ab.- ‘rr I End elevation of root vegetable silo with centrefluming channel Silos The construction of the silos is quite a simple matter and a typical sue for a 100 ton unit would be 30m by 4m. The side walls are lm in height and constructed of 23cm thick masonry. Both ends of the silo are left open to allow incoming bulk loaders or tipper lorries to discharge their loads. The concrete bottom of the silo slopes from either side wall to the fluming channel in the middle. This runs longitudinally down the whole length of the silo with a fall of 50cm in the 30m length. The width of the channel is 30cm, and this is rebated to take 7.5cm thick timber cover boards which are fitted flush with the sloping silo bottom. The shallowest point of the flume channel must be not less than 15cm deep, and it is from here that the water supply is introduced from powerful centrifugal pumps with a capacity of 91,000 to 136,000 litres per hour. The cover boards are removed in that part of the silo which requires to be emptied, and the vegetables feed in a steady stream into the fluming channel, whence they are carried along with the flow of 29
water. Beyond the end of the silo, the fluming channel continues, maintaining the same rate of fall, to the prewasher and destoner. At this point the fluming water is discharged, and the vegetables are elevated into the processing plant In setting out this system, levels have to be carefully studied, as it may not be possible to arrange for a natural fall for the whole length of the flum and some elevation may be necessary prior to the washer. This can only be decided by the processor in the light of local circumstances Adequate protection from bad weather must be provided, and the silos should be under cover in suitable outbuildings wherever possible Alternatively, 50 ton storage bins may be erected over the silos to discharge directly into the flume channels. a mobile elevator will be needed to fill these from bulk transport POWER Electricity requirements for the putative plant will be in the range 300- 400KW. Whilst this will normally be taken from the mains, it is a wise precaution to have some internal generating facilities, even if only to keep essential plant running in the event of a mains power failure Downtime in continuous process is very expensive indeed and, apart from raw material in mid-process being at risk, heavy standing charges have also to be met from reserves. Also, when highly perishable vegetables, such as vined peas, are being handled, every hour lost by breakdown is irrecoverable, as the vining programme on the farms is geared accurately to the plants optimum processing throughput, and any hold-up at the factory can result in the loss of many tons of raw material, which could be the processors responsibility. This situation is very obvious when it is realised that the whole seasons pack of fresh peas has to be processed in six weeks, therefore every hour of electrical or mechanical breakdown in the working week can Precipitate disastrous losses for both the grower and the dehydrator. The economics of dehydration are elaborated in a later chapter but it cannot be stressed too strongly at this point that any steps, which can be taken by way of ensuring complete reliability and continuity of the power supply, should be taken, in he full knowledge of the consequences of breakdown It is sound practice to install electric motors rated somewhat in excess of their actual duty, and to ensure that they are adequately protected against water,steam and conditions of high humidity, remembering also that they will probably be running continuously for many hours. It is possible to spray windings, starters and switchgear with a water repellent compound nd this precaution should be taken by the shift maintenance staff as a regular procedure
water. Beyond the end of the silo, the fluming channel continues, maintaining the same rate of fall, to the prewasher and destoner. At this point the fluming water is discharged, and the vegetables are elevated into the processing plant. In setting out this system, levels have to be carefully studied, as it may not be possible to arrange for a natural fall for the whole length of the flume, and some elevation may be necessary prior to the washer. This can only be decided by the processor in the light of local circumstances. Adequate protection from bad weather must be provided, and the silos should be under cover in suitable outbuildings wherever possible. Alternatively, 50 ton storage bins may be erected over the silos to discharge directly into the flume channels. A mobile elevator will be needed to fill these from bulk transport. POWER Electricity requirements for the putative plant will be in the range 300- 400KW. Whilst this will normally be taken from the mains, it is a wise precaution to have some internal generating facilities, even if only to keep essential plant running in the event of a mains power failure. Downtime in a continuous process is very expensive indeed and, apart fmm raw material in mid-process being at risk, heavy standing charges have also to be met from reserves. Also, when highly perishable vegetables, such as vined peas, are being handled, every hour lost by breakdown is irrecoverable, as the vining programme on the farms is geared accurately to the plant’s optimum processing throughput, and any hold-up at the factory can result in the loss of many tons of raw material, which could be the processor’s responsibility. This situation is very obvious when it is realised that the whole season‘s pack of fresh peas has to be processed in six weeks, therefore every hour of electrical or mechanical breakdown in the working week can precipitate disastrous losses for both the grower and the dehydrator. The economics of dehydration are elaborated in a later chapter but it cannot be stressed too strongly at this point that any steps, which can be taken by way of ensuring complete reliability and continuity of the power supply, should be taken, in the full knowledge of the consequences of breakdown. It is sound practice to install electric motors rated somewhat in excess of their actual duty, and to ensure that they are adequately protected against water, steam and conditions of high humidity, remembering also that they will probably be running continuously for many hours. It is possible to spray windings, starters and switchgear with a water repellent compound, and this precaution should be taken by the shift maintenance staff as a regular procedure. 30