英文文献年产万吨的苹果汁工厂设计Word格式.docx

1、Roofs and ceilingsWallsWindows and doorsFloorsLighting and powerWater supply and sanitationLayout of equipment and facilities In general, a building should have enough space for all production processes to take place without congestion and for storage of raw materials, packaging materials and finish

2、ed products. However, the investment should be appropriate to the size and expected profitability of the enterprise to reduce start-up capital, the size of any loans taken out and depreciation and maintenance charges.In tropical climates, overhanging roofs keep direct sunlight off the walls and out

3、of the building. This is particularly important when processing involves heating, to make working conditions more comfortable. Fiber-cement tiles offer greater insulation against heat from the sun than galvanized iron sheets do. High level vents in roofs both allow heat and steam to escape and encou

4、rage a flow of fresh air through the processing room. The vents must be screened with mesh to prevent insects, rodents and birds from entering the room. If heat is a serious problem, the entrepreneur could consider fitting electric fans or extractors, although this clearly increases capital and oper

5、ating costs. Rafters or roof beams within the processing and storage rooms are unacceptable. They allow dust to accumulate, which can fall off in lumps to cause gross contamination of products. Similarly, insects can fall from them into products. They also allow paths for rodents and birds, with con

6、sequent risks of contamination from hairs, feathers or excreta. It is therefore essential to have a paneled ceiling fitted to any processing or store-oom, with careful attention when fitting them to ensure that there are no holes in the paneling. Care should also be taken to prevent birds, rodents a

7、nd flying insects gaining access to the processing room through gaps in the roof structure or where the roof joins the walls. As a minimum requirement, all internal walls should be rendered or plastered with a good quality plaster to prevent dust forming in the processing room. An experienced plaste

8、rer should be used to ensure that no cracks or ledges remain in the surface finish, which could accumulate dirt and insects. The lower area of walls, to at least 1.08 metres （four feet） above the floor, is most likely to get dirty from washing equipment, from product splashing etc. and special atten

9、tion should be paid to ensure that this area is easily cleaned. Higher areas of walls should be painted with a good quality emulsion. The lower parts of walls should be either painted with a waterproof gloss paint, preferably white, to allow them to be thoroughly cleaned, or ideally they should be t

10、iled with glazed tiles. If tiling a process room is too expensive, it is possible to select particular areas such as behind sinks or machinery and only tile these parts. In some countries there is a legal requirement for specified internal finishes and this should be checked with the Ministry of Hea

11、lth or other appropriate authority （see also Section 2.4.2） Window sills should be made to slope for two reasons: to prevent dust from accumulating and to prevent operators from leaving cloths or other items lying there, which in turn can attract insects. Windows allow staff to work in natural dayli

12、ght, which is preferable to and cheaper than electric lighting. However, in tropical climates there is a natural inclination for workers to open windows to allow greater circulation of fresh air. This provides easy access for flying insects, which can readily contaminate the product. Windows should

13、therefore be fitted with mosquito mesh to allow them to be left open. Normally doors should be kept closed, but if they are used regularly there is again a tendency for them to be left open with similar consequences of animals and insects entering the plant. In this case, thin metal chains or strips

14、 of material that are hung vertically from the door lintel may deter insects and some animals, while allowing easy access for staff. Alternatively mesh door screens can be used. Doors should be fitted accurately so that there are no gaps beneath them and all storeroom doors should be kept closed to

15、prevent insects and rodents from destroying stock or ingredients. It is essential to ensure that the floors of processing rooms and storerooms are constructed of good quality concrete, smooth finished and without cracks. In some developing countries, it is possible to buy proprietary floor paints or

16、 vinyl based coatings, but these are usually very expensive. Generally, it is not adequate to use the red wax floor polishes that are commonly found in households, as these wear away easily and could contaminate either products or packages. Over time, spillages of acidic fruit products react with co

17、ncrete and cause it to erode. Attention should therefore be paid to cleaning up spillages as they occur and to regularly monitor the condition of the floor. The comers where the floor and the walls join are places for dirt to collect. During construction of the floor, it should therefore be curved u

18、p to meet the wall. It is possible to place fillets of concrete （or coving） in the comers of an existing floor to fill up the right angle, but care is needed to ensure that new gaps are not created which would harbour dirt and insects. The floor should slope at an angle of approximately 1 in 8 to a

19、central drainage channel. At the end of a days production, the floor can be thoroughly washed and drained. Proper drainage prevents pools of stagnant water forming, which would in turn risk contamination of equipment and foods. The drainage channel should be fitted with an easily removed steel grati

20、ng so that the drain can be cleaned. Where the drain exits the building, there is a potential entry point for rodents and crawling insects unless wire mesh is fitted over the drain opening. This too should be easily removed for cleaning. General room lighting should be minimized wherever possible. F

21、ull use should be made of natural daylight, which is both free and better quality light, especially for intricate work. Where additional lighting is needed, florescent tubes are cheaper to operate than incandescent bulbs. However, if machinery is used that has fast moving exposed parts, these should

22、 be lit with incandescent bulbs and not tubes. This is because even though the parts should have guards fitted, a rotating machine can appear to stand still if its speed matches the number of cycles of the mains electricity that powers fluorescent tubes - with obvious dangers to operators. All elect

23、ric power points should be placed at a sufficiently high level above the floor that there is no risk of water entering them during washing the floor or equipment. Ideally, waterproof sockets should be used. It is important to use each power point for one application and not use multiple sockets whic

24、h risk overloading a circuit and causing a fire. If there are insufficient power points for the needs of a process, additional points should be installed, even though this is more expensive. All plugs should be fitted with fuses that are appropriate for the power rating of the equipment and ideally

25、the mains supply should have an earth leakage trip switch. If three-phase power is needed for larger machines or for heavy loads from electric heating, it is important that the wiring is installed by a qualified electrician to balance the supply across the three phases. Water is essential in nearly

26、all fruit and vegetable processing, both as a component of products and for cleaning. An adequate supply of potable water should therefore be available from taps around the processing area. In many countries, the mains supply is unreliable or periodically contaminated and it is therefore necessary f

27、or the entrepreneur to make arrangements to secure a regular supply of good quality water each day. This can be done by installing two high level, covered storage tanks either in the roof-space or on pillars outside the building. They can be filled alternately when mains water is available and while

28、 one tank is being used, any sediment in water in the other tank is settling out. As sedimentation takes several hours, the capacity of each tank should be sufficient for one days production. The tanks should have a sloping base and be fitted with drain valves above the slope and at the lowest point

29、. In use, water is taken from the upper valve and when the tank is almost empty, the lower valve is opened to flush out any sediment that has accumulated. Water that is included in a product should be carefully treated to remove all traces of sediment and if necessary, it should be sterilised. This

30、is particularly important if the product is not heated after water has been mixed in as an ingredient. There are four ways of treating water at a small scale: by filtration; by heating; by ultra-violet light and by chemical sterilants, such as hypochlorite （also named chlorine solution or bleach）. O

31、ther water treatment methods are generally too expensive at a small scale of operation. Filtration through domestic water filters is slow, but having made the capital expenditure, it is relatively cheap. Larger industrial filters are available in some countries. Heating water to boiling and holding

32、it at that temperature for 10-15 minutes is simple and has low capital costs, but it is expensive because of fuel costs and it is time consuming to do routinely. Heating sterilises the water but does not remove sediment and boiled water may therefore require filtering or standing to remove sediment. Ultra-violet light destroys micro-organisms in water and commercial water treatment units that use this principle （Figure 38） are coming down in price to the point that