Abstract:
The invention relates to a method and an apparatus for cleaning industrial pipe systems, preferably pipe systems used in food industry, such as meat, fish and vegetable industry. The method for cleaning industrial pipe systems, includes the steps of feeding a detergent together with liquid and granules, having a diameter, in batches only into a small part of a pipe, having a cross-section, to be cleaned, whereby one wash batch has a volume in liters, which is 0.05-0.3 times the numerical value of the cross-section in square centimeters of the pipe, creating a negative pressure in the pipe, and bringing the wash batch to flow in the pipe by means of the negative pressure for cleaning and mechanically treating the walls of the pipe. The invention relates also to an apparatus for carrying out the method. As an essential part, the apparatus includes a washing center ( 9 ) that functions as a source of the batches cleaning the pipe ( 4 ).

Description:
[0001]    This application is a continuation of International application PCT/FI99/00953, filed Nov. 17, 1999 which claims priority of Finnish application No. 982495, filed Nov. 18, 1998, the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a method for cleaning industrial pipe systems, more precisely to a method for cleaning industrial pipe systems, preferably pipe systems used in food industry, such as meat, fish and vegetable industry, where detergent and liquid are fed into a pipe to be cleaned, and a pressure difference is created in the pipe and the detergent and liquid are brought to flow in the pipe by means of a pressure difference in order to clean the pipe.  
           [0003]    In food industry the pipes transferring foodstuffs have to be cleaned in due time for hygienic reasons in order not to contaminate the foodstuffs transferred therein. A conventional way to clean these pipes is to feed water and detergent through the pipes. The cleaning process also includes cleaning with a disinfectant and rinsing. For example in dairy industry the cleaning agent is often fed in from one end of the pipe to be cleaned using pumps, in which case the flow is maintained until the cleaning agent flows out from the other end of the pipe. The required power of the pump has to be high, since the length of the pipe can extend up to hundreds of meters and the flow rate is, for example, 2-4 m/s. As the diameter of the pump is large, considerable amounts of cleaning agent and disinfectant have to be fed. Owing to the above, cleaning a pipe becomes very expensive.  
           [0004]    The cleaning agent, disinfectant and rinsing agent (typically water) can be brought to flow using negative pressure as an alternative for using a pump, which is the conventional means for causing the flows. This is known from slaughtering lines. However, known systems utilizing negative pressure have not been able to provide a desired and an adequate cleaning result.  
           [0005]    The invention also relates to an apparatus for cleaning industrial pipe systems, preferably pipe systems used in food industry, such as meat, fish and vegetable industry, comprising feeding means for feeding liquid into a pipe to be cleaned and a pressure unit for removing the liquid fed into the pipe from the pipe by means of a pressure difference.  
           [0006]    Known apparatuses are arranged to transfer, depending on the work phase, washing agent, disinfectant or rinsing agent into the pipe along the entire length of the pipe. The water amounts used are generally large and the actual cleaning phase includes several feedings of the substances, as the inner surface of the pipe is rarely adequately cleaned during one treatment. On account of the above, known apparatuses do not enable the pipe systems to be cleaned rapidly and inexpensively.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0007]    It is an object of the invention to provide a method and an apparatus removing said drawbacks. In order to achieve this the present invention provides a method method for cleaning industrial pipe systems, having pipe walls, by mechanically treating the walls thereof, said method comprising  
           [0008]    feeding a detergent together with liquid and granules, having a diameter, in batches only into a small part of a pipe, having a cross-section, to be cleaned, whereby one wash batch has a volume in liters, which is 0.05-0.3 times the numerical value of the cross-section in square centimeters of the pipe;  
           [0009]    creating a negative pressure in the pipe; and  
           [0010]    bringing the wash batch to flow in the pipe by means of the negative pressure for cleaning and mechanically treating the walls of the pipe.  
           [0011]    Preferred embodiments of the method of the invention are disclosed in the attached claims 2-8.  
           [0012]    One of the greatest advantages of the method of the invention is that it allows industrial pipe systems having a large diameter in particular to be cleaned considerably more economically and more appropriately than previously.  
           [0013]    The present invention provides for an apparatus for cleaning industrial pipe systems, having pipe walls, by mechanically treating the walls thereof, said apparatus comprising feeding means for feeding liquid and granules into a pipe to be cleaned and a low pressure unit for removing the liquid and granules fed into the pipe from the pipe by means of a negative pressure, said apparatus further comprising a washing center arranged by means of feeding means including a feeding pipe to feed liquid and granules into the pipe to be cleaned, the washing center comprising a container that comprises an inlet which is connected to the pipe to be cleaned for receiving material arriving from the container, removing means connected to the feeding pipe for feeding liquid through the feeding pipe to the pipe to be cleaned, the container comprising a granule space for granules, having a diameter, wherein the pipe to be cleaned includes a dosage valve for dispensing a detergent together with liquid and granules in the form of a wash batch only into a small portion of the pipe to be cleaned, the granule space comprising a feeding surface for feeding granules, said feeding surface being provided with holes having a diameter which is smaller than the diameter of the granules, the granule space being connected to the feeding pipe  
           [0014]    The preferred embodiments of the apparatus of the invention are disclosed in the attached claims 11-13.  
           [0015]    One of the greatest advantages of the apparatus of the invention is that it allows industrial pipe systems having a large diameter in particular to be cleaned considerably more economically and more appropriately than previously. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    In the following the invention will be described by means of a preferred embodiment with reference to the attached drawing, in which  
         [0017]    [0017]FIG. 1 shows an apparatus of the invention,  
         [0018]    [0018]FIG. 2 shows an important part of the apparatus in FIG. 1, and  
         [0019]    [0019]FIG. 3 is a top view along the line III-III illustrating a part of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    [0020]FIG. 1 shows a poultry slaughtering line comprising a conveyor (not shown in the Figure) for conveying a slaughter animal, like a chicken or the like, to a work station  1 . Typically there are several work stations  1 ,  2  but for the sake of simplicity FIG. 1 only shows two work stations.  
         [0021]    The work station  1  comprises a funnel  3 , from where a process pipe  4  leads to a separating unit  5 . A low pressure unit  6  is connected to the separating unit  5  for creating negative pressure to the separating unit. The separating unit  5  comprises a container  7  which can be opened and closed from above. A pipe  8  leads from the bottom of the container  7  to a washing center  9 . The washing center  9  is by means of a feeding pipe  10  connected to the process pipe  4 , the connection point being positioned relatively close to the funnel  3 . A valve  11  is arranged at that end of the feeding pipe  10  which is close to said connection point. Closing the valve  11  prevents the medium from being transferred from the feeding pipe  10  to the process pipe  4  or from the process pipe to the feeding pipe. The valve  11 , which can be referred to as a dosage valve, is arranged close to an end  12  of the pipe  4  comprising the funnel in such a manner that between the end and the valve a pipe portion  13  is formed, whose length and volume are small compared to the total length and total volume of the pipe. The volume of the pipe portion  13 , in liters, is 0.5-3 times the numerical value of the cross-section in square centimeters of the pipe  4 , and divided by ten, i.e. the volume is 11.25-67.5 l for a pipe having a 225 square centimeter cross-section (the diameter of the pipe being 169 mm) and the volume is 45-270 l for a pipe having a 900 square centimeter cross-section (the diameter of the pipe being 339 mm). Thus the length and volume of the pipe portion  13  form only a fraction, for example 0.1-10%, of the total length and volume of the pipe  4 .  
         [0022]    The pipe portion  13  comprises, as shown in FIG. 1, a portion that points upwards. On this account the pipe portion  13  can be filled with the batches described below that form a “water lock” to the pipe  4 . Alternatively the pipe portion  13  may include a valve (not shown) that enables the pipe portion  13  to be filled with a batch forming the “water lock”.  
         [0023]    Reference numeral  14  indicates a wash ball feeding apparatus, which will be described below.  
         [0024]    Two water feeding lines  15 ,  16  lead to the washing center  9  for adding pure water from above to a container  25  of the washing center.  
         [0025]    Reference numeral  17  indicates a detergent container that is arranged to feed detergent through a pipe  18  to the washing center container  25  from above.  
         [0026]    Reference numeral  19  indicates a disinfection container arranged to feed detergent through a pipe  20  to the washing center container  25  from above.  
         [0027]    The end of the feeding pipe  10  on the side of the washing center comprises three valves, what are known as a granulate valve  21 , a washing water valve  22  and a dewatering valve  23 , the function of which will be described below.  
         [0028]    A pump  24  is arranged to the feeding pipe  10  for transferring medium from the washing center to the pipe portion  13 .  
         [0029]    [0029]FIG. 2 shows in greater detail the essential components of the washing center in the apparatus.  
         [0030]    The washing center container  25  comprises a space, what is known as a granule space  26 , for plastic granules  52  which are 1-10 mm in diameter. The diameter of the granules is preferably within 1-3 mm. The plastic granules are supported from below by a tapering feeding plate  27  defining the granule space as conical. A dashed line  28  indicates the granule level. The feeding plate  27  is perforated and comprises holes  51  which are smaller than the diameter of the granules to be used. The diameter of the holes  51  is preferably about 1 mm. The plastic granules are worn in use, so that before long the diameter thereof goes below 1 mm, whereafter these small, worn granules fall through the holes of the feeding plate  27  to a sediment space  28  at the bottom of the container where sediment is collected. The sediment is removed along a pipe  41  to a drain by opening the flap valve  23 .  
         [0031]    The lower end of the granule space  26  comprises a delivery outlet  29  that can be closed and opened in the upright direction using an adjusting cone  30  which can be transferred by means of a support rod  31  or another valve element. The adjusting cone  30  is placed at a distance from the delivery outlet  29  so that an appropriate ring-surface is obtained for feeding granules  52 . The adjusting cone  30  is perforated, thus allowing the liquid to be transferred through the holes.  
         [0032]    The granule space  26  is connected to a feeding pipe  10  through a pipe  34 , whereto the valve  21  (granulate valve) is connected.  
         [0033]    Beneath the granule space  26  there is a liquid space  35  for water. The water space  35  is connected to the feeding pipe  10  through a pipe  36 , whereto the valve  22  (washing water valve) is connected. The upper end of the pipe  36  is above the sediment space  28 .  
         [0034]    Reference number  37  indicates an overflow pipe that leads to the drain.  
         [0035]    Heating elements  38 - 40  are placed inside the container  25  in order to keep the water in a liquid space  35  at a desired temperature.  
         [0036]    The material and the liquids are fed into the upper end of the container  25  through said pipes  8 ,  15 ,  16 ,  18  and  20 .  
         [0037]    The operation of the apparatus is described in the following.  
         [0038]    The process is initiated because the process pipe  4  is dirty and should be washed. The process pipe  4  has become dirty since it has been used to transfer slaughtering material to the separating unit  5 . The slaughtering material is removed through a lid at the bottom of the separating unit  5 .  
         [0039]    When the pipe  4  is cleaned after use, the following steps are performed:  
         [0040]    A: Pre-wash or first rinse of the pipe,  
         [0041]    B: Wash of the pipe,  
         [0042]    C: Final wash of the pipe,  
         [0043]    D: Intermediate rinse of the pipe,  
         [0044]    E: Disinfection of the pipe and  
         [0045]    F: Final rinse of the pipe.  
         [0046]    During the pre-wash of the pipe, the valve  22  in the washing center  9  is opened and water at a temperature within 30-50° C. is fed from the water space  35  in the washing center into the feeding pipe  10 . A particularly appropriate temperature is about 37° C. The temperature is selected so that it will not exceed the limit where the proteins in the pipe  4  “burn” to the pipe. The amount of water to be fed is small compared to the volume of the pipe  4 . This water amount is fed using the pump  24  when the valves  11  and  42  are open and when a valve  43 , what is known as the air valve, is closed at the pipe portion  13  of the pipe  4 . A ball  44  of flexible material, whose inner diameter substantially corresponds to the one of the pipe  4 , or another kind of piece is fed from the wash ball feeding apparatus  14  to the funnel  3  and further to the pipe portion. The water in the pipe portion  13  and the ball form a pre-wash batch. The length and volume of the pipe portion  13  are small compared to the length and volume of the pipe  4 . The length of the pipe portion  13  is preferably selected so that the pre-wash batch fills the pipe portion. The volume of the pre-wash batch is preferably 20-40 l, when the inner diameter of the pipe  4  is 150 mm, but may in a wider sense be for example 0.1-10% of the volume of the pipe  4 .  
         [0047]    After this the valves  11  and  43  are closed. The low pressure unit  6  is switched on, whereafter the pressure difference between the end  12  of the pipe comprising the funnel and the end of the pipe comprising the separating unit  5  is 0.2-0.5 bar that brings the pre-wash batch to flow in batches in the pipe  4  to the separating unit  5 , and cleans the pipe walls from coarse, or large, loose material, which may fall out through the lid at the bottom of the separating unit. When the batch moves the ball  44  functions as a scraping device.  
         [0048]    Water is fed into the washing center container  25  when the pipe is being washed. Detergent is also fed into the container  25  using a pump  45 . The granule space  26  comprises granules. The water in the liquid space  35  is heated to a temperature that ranges from 50 to 100° C. (the temperature thus remaining beneath the boiling point of water). Water is fed into the feeding pipe  10  through the pipe  36  and the valve  22 . Granules are fed into the feeding pipe  10  through the pipe  34  and the valve  21 . The amount of water, detergent and granules to be fed is small compared to the volume of the pipe  4 . Water, detergent and granules are fed in batches by means of the pipe  24  when the valves  11  and  42  are open and when the valve  43 , what is known as the air valve, is closed to the pipe portion  13  of the pipe  4 . The water, detergent and the granules in the pipe portion  13  form a wash batch. The volume of the wash batch is, for example, 0.1-10% of the volume of the pipe  4 . An adequate washing result is obtained when the percentage of the granules is 30 to 70% by volume of the wash batch volume.  
         [0049]    After this the valves  11  and  43  are closed. The low pressure unit  6  is switched on, whereafter a pressure difference of 0.2 to 0.5 bar is formed to the pipe  4 , and the wash batch flows in the pipe  4  as a batch to the separating unit  5  on account of the pressure difference and cleans the inner pipe walls. The water, detergent and granules in the wash batch are conveyed along the pipe  8  back to the granule space  26 .  
         [0050]    Before washing takes place the valve  42  is closed and the valve  43  is opened so that the wash batch can be transferred to the separator  5  using negative pressure during the wash. The work stations  1 ,  2  may have a mutual air valve  43  that can be referred to as a line rinsing valve.  
         [0051]    The wash described above is repeated 1 to 5 times if necessary.  
         [0052]    During the final wash of the pipe  4 , water at a temperature within 30-70° C. and a wash ball are fed into the pipe portion  13 . The final wash batch formed thereof having a small volume is fed into the pipe  4  as described above, whereafter water is emptied from the container  25 .  
         [0053]    During the intermediate rinse of the pipe  4 , water is fed into the container  25  of the washing center. The water in the liquid space  35  is heated to a temperature within 30-50° C. Water is fed in batches into the feeding pipe  10  and to the pipe portion  13  using a pump. An intermediate rinse water batch, the volume of which is small compared to the total length of the pipe  4 , is then fed along the pipe  4  into the separating unit  5 .  
         [0054]    When the pipe  4  is being disinfected, water is fed into the washing center container  25 . A disinfectant is also fed into the container  25  using a pump  46 . When the disinfectant is fed into the container  25  from above through the pipe  20 , the disinfectant cleans the granules in the granule space  26 . The water in the liquid space  35  is heated to a temperature within 50-70° C., preferably 60° C. Water is fed into the feeding pipe  10 . The amount of water and disinfectant to be fed is small compared to the volume of the pipe  4 . The water and the disinfectant are fed into the pipe portion  13 . Together the water and disinfectant in the pipe portion  13  form a disinfectant batch. The volume of the disinfectant batch is, for example 0.1-10% of the volume of the pipe  4 .  
         [0055]    The disinfectant batch is transferred in batches in the pipe  4  to the separating unit  5 .  
         [0056]    The disinfection described above is repeated 1-5 times if necessary.  
         [0057]    The final rinse of the pipe  4  is conducted in the same way as the intermediate rinse, whereby the rinse batch can be referred to as the final rinse water batch.  
         [0058]    Said batches are transferred in the pipe at a velocity of 10 to 40 m/s, whereby an optimal result is achieved during cleaning.  
         [0059]    The washing center  9  functions as a source to the batches cleaning the pipe.  
         [0060]    The pipe  47 ,  4  connected to the work station  1  is cleaned in the same way as the pipe  4  connected to the work station  2 . The pipes can be cleaned at the same time or at different times by appropriately controlling the valves  11 ,  42 ,  43 ,  48 - 50 .  
         [0061]    The invention has above been described by means of one example only and it is therefore pointed out that the invention can be implemented in various ways deviating from the example described above within the scope of the attached claims. Hence, the structure of the washing center  9  can, for example, be different and instead of the valves  11 ,  42 ,  43  another valve arrangement can be used for filling the pipe portion  13  with a wash batch and with other batches associated with the method. The plastic granule volume of the batch volume may remain outside the ranges presented. Granules made of other materials may also be used instead of plastic granules. The liquid used for cleaning can be water that contains various chemicals. The method is still economical if a liquid that is significantly more expensive than water is used, since the volume of the wash batches and cleaning batches remains small even if the diameters of the pipes to be cleaned are large (for example over 100 mm). The detergent may be any detergent generally used in the field and any alkaline or acid liquid may function as the detergent. During cleaning the pressure to be used does not have to create a pressure difference of 0.2 to 0.5 bar to the pipe  4 , although such a pressure difference has proved to be very effective (since it does not cause any blockages in the pipe to be cleaned): at a wider scale the pressure difference may range from 0.1 to 0.97 bar. Water heated up to a 100° C. temperature can be used for the final wash, intermediate rinse, disinfection and final rinse of the pipe. The method and the apparatus can basically be applied for cleaning any pipe systems, such as cleaning the pipe systems conveying food debris or concrete.