CTG TSP1 EU TRANSPORTATION, STORAGE AND PROCESS

Transcription

1 TRANSPORTATION, STORAGE AND PROCESS CTG TSP1 EU TRANSPORTATION, STORAGE AND PROCESS

2 Tank Cleaning Technology Index Preface page 3 Common Tank Cleaning Methods page 4 Tank Cleaning Devices page 4 Cleaning Dynamics page 12 The Science Of Tank Cleaning CIP (Clean In Place) Systems page 17 Cleaning Validation and CIP Optimization page 18 Technical Publications PNR manufactures a complete range of spray nozzles for industrial applications, as well as products and systems specially designed for specific industries. Information about our Company and our product range is available through the following publications PRODUCT RANGE CTG TV BR GENERAL PURPOSE SPRAY NOZZLES CTG UG BR AIR ASSISTED ATOMIZERS CTG AZ BR COMPLEMENTARY PRODUCTS AND ASSEMBLY FITTINGS CTG AC BR INDUSTRIAL TANK WASHING SYSTEMS CTG LS BR EVAPORATIVE COOLING LANCES CTG LN BR FIRE FIGHTING PRODUCTS CTG FF BR PAPERMILL PRODUCTS CTG PM BR STEELWORK NOZZLES CTG SW BR SPRAYDRY NOZZLES CTG SP BR Our Company has qualified its Quality Management System according to the ISO 9001/2000 Norms. 2 DNV Cert AQ MIL SINCERT Copyright: Troy Humphries

3 Tank Cleaning Technology 01 - Preface The Science of Tank Cleaning Technology is a culmination of various disciplines and includes but is not limited to the application of mechanical function, hydraulics, physics, chemistry, and instrumentation. The application of these various disciplines for a given Tank Cleaning requirement will also vary from the simplistic to the very complex. The safe, efficient, and economic cleaning of tanks and vessels has become a major consideration for a number of industries. Today, less than adequate cleaning can result in... Off-Spec Products Lost production Excessive waste Excessive energy consumption Unsafe working conditions All of these factors can result in lost revenues and in some cases loss of consumer confidence. The purpose of this paper is to make you aware of the factors to be considered when analyzing a tank cleaning requirement. This paper should not be considered conclusive as the available technologies are ever changing. You will, however, receive information about various types of cleaning devices, CIP Design Considerations, Cleaning Dynamics, Validation Methodologies and more. Cleaning of vessels and tanks is not a new requirement. In ancient Egypt, manual cleaning of large wine amphorae was very common. However, it is amazing that today this method of cleaning is still quite prevalent. It is estimated that approximately 40% of the tank cleaning accomplished worldwide today is manually achieved and another 15%-20% is accomplished inefficiently compared to the technology available. The primary reason is due to insufficient knowledge and understanding of today's cleaning technologies. 3

4 Tank Cleaning Technology 02 - Common Tank Cleaning Methods Most all Tank Cleaning Methods fall into the following categories: Manual The process whereby a human being is placed in the tank or external to the tank and cleaning is accomplished by either hand/brush or with wash hose (high and low pressure). Fill and Dump (Floatation) The process whereby a tank or process vessel is filled with the required cleaning fluid. Agitation and heat may be applied. Automated - Portable The process whereby an automated cleaning device is placed in the tank; either static or dynamic; then removed after the cleaning process has been completed. Automated - Fixed In Place The process whereby an automated cleaning device is placed permanently in the tank; either static or dynamic; and is not removed during process, storage or transportation Tank Cleaning Devices The most optimal cleaning process is the one which brings back the tank or vessel into satisfactory operating condition by using: the shortest possible time the least volume of cleaning liquid the least amount of chemicals the least amount of energy while at the same time being.., Reliable Safe Economical To accomplish this, a properly engineered and installed system along with the proper selection and placement of the automated cleaning device is imperative Types of Automated Cleaning Devices 4 Automated cleaning devices fall into the following primary categories: Static Dynamic

5 Tank Cleaning Technology Static Devices Static devices are any cleaning device that does not move and has no moving parts (Figure 1). Devices within this category are: Spray Balls Spray Rings Static Nozzles Figure 1 There are variations of these devices in that they can be directional and vary in their pressure and flow rates. Primary advantages and disadvantages of these devices are as follows: Advantages - Mechanically they are not complicated - Low purchase cost - Little to no maintenance required - Disassembly and inspection process by regulatory authorities is easy Disadvantages - High flow rates compared to other technologies - Low transference of energy to tank surfaces - Blockage of cleaning ports more prevalent - Limited tank size capability - Validation of device operation is difficult compared other technologies Figure 2 Dynamic Devices - RJH Non-Integrated Fluid Drives (Auxiliary) Non-Integrated fluid driven rotating jet-heads1 (RJH) and spheres are those which require a power source to operate the gear mechanism other than the cleaning media (Figure 2). In other words, to rotate the head or sphere a pneumatic, electric, or hydraulic power source is required. A rotating jet-head lays a cleaning pattern by rotation of its main body axis (the horizontal plane) while at the same time rotating its nozzle hub (the vertical plane). A full 360 degree or directional indexing can be accomplished (Figure 3). Figure 3 5

6 Tank Cleaning Technology Dynamic Devices - Rotating Spray Head (RSH) A rotating sphere is either a rotating ball or disc with strategically drilled ports or slots for the expulsion of the cleaning fluid (See Figure 4). An RSH is normally set into rotation by reaction of the fluid flow against the sphere or disc. As the fluid is discharged through the device, the reaction of the fluid force will set the ball of the RSH or disc in rotation. Some rotational values on some types are controlled; but in most cases it is not. Advantages - Good transfer of energy to tank surfaces - Lower flow rates - Reduced cleaning times compared to static devices - Reduced chemical usage compared to static devices - Normally improved cleaning results compared to static devices - Broader range of tank sizes compared to static device Figure 4 Disadvantages - Mechanically more complicated - Higher purchase cost - Self cleaning can be more difficult to accomplish Dynamic Devices - Integrated Turbine Fluid Drives An Integrated Turbine Fluid Drive is powered by the cleaning fluid that flows through it. In the case of a rotating jet-head (RJH), normally a turbine is set in rotation by the passing of fluid across the turbine vanes (See Figure 5). This in turn rotates the turbine shaft and associated gears. The device is then set into rotation. Advantages - Excellent transfer of energy to tank surfaces - Low flow rates; relative to tank size capabilities - Reduced cleaning times - Reduced chemical usage - Improved cleaning results - Validation of operation is easy - Broadest range of tank sizes - Normally offers the best cost-to-benefit ratio in terms of cleaning cost. Figure 5 6 Disadvantages - Mechanically more complicated - Highest purchase cost of all dynamic devices - Unless properly designed, self-cleaning is difficult

7 Tank Cleaning Technology How Automated Cleaning Devices Function Figure 6 Figure 7 2 A shielded or shadow area is the surface within a tank or vessel that cannot be projected upon directly from a given position of the cleaning device. 3 The track width is the area between where the center of the jet impinges upon the tank surfaces and the next adjacent jet track. Static Devices Static devices predominantly clean the host tank or vessel by cascading the cleaning media on the surfaces of the subject structure. This is commonly referred to as sheeting. The most common device used is a spray ball. A spray ball atomizes the fluid flow within a few feet of the device and a dense mist is projected onto a portion of the subject structure. Solubility of the soil in water or the CIP solution is relied upon to provide the cleaning action required. There is little to no impact values onto the surfaces as a whole. Static nozzles basically accomplish cleaning in a similar way except that they can offer increased impact and cleaning radius due to nozzle design but is usually very localized. These devices rely more heavily on fluid flow, chemical assistance, time, and temperature than dynamic cleaning devices. However, in many cases, this is all that is required to place the subject tank or vessel back into a satisfactory operating condition. Installation of these devices can be accomplished in a number of ways. The most common for the hygienic industry is the slip-joint or tri-clamp fitting (See Figure 7). Placement of the static device is predominantly located in the upper areas of the vessel (See Figure 6) so that the fluid flow will come in contact with these upper surfaces, thus allowing gravity to assist in dispersing the media to the other portions of the vessel. Directional units are available if only a portion of the vessel is desired to be cleaned. This is many times the case for open-top tanks or process vessels. Dynamic Devices - Rotating Jet-Heads (RJH) and Rotating Spray Heads (RSH) As the basic cleaning operation of Auxiliary and Integrated Turbine Fluid Drives are similar, we will not segregate the two in this section. Rotating Jet-Heads clean the host tank or vessel by projecting a preprogrammed or programmable cleaning pattern on to the internal structures of the tank (See Figure 3). This pattern is a series of jet projections onto the vessel structures. Pattern build-up and density can vary from one manufacturer of the device to another. Complete cleaning patterns can be developed in as little as 5-6 minutes or as long as several hours. It is many times not necessary to complete a pattern in order to render a tank clean. Shielded (shadow) areas 2 to the cleaning device can many times be cleaned with a deflective jet (See Figure 8). Automatic indexing and the deflective quality of the jet is the primary advantage of the rotating jet-head over that of the static device and that of the rotating sphere or disc. The track width 3 is cleaned by the jet spread that occurs upon impingement. Rotating spheres and discs do not develop patterns in the same way as the RJH. In most cases, these devices project either a vertical or horizontal sheet or stream of cleaning fluid. The sphere or disc rotates 360 7

8 Tank Cleaning Technology degrees and projects the cleaning fluid throughout the structure. Rotating jet-heads, spheres and discs can project onto only a designated portion of the subject vessel (directional devices) or offer 360 degree coverage. Principal factors to be considered in the success of a Rotating Jet- Head are: P (Delta P) across the cleaning device. The differential pressure loss from the entry of the cleaning media to its exit at the nozzle is an important factor. Should the device consume an inordinate amount of the hydraulic energy, jet impacts and distances will be negatively affected. An easy way to check this is to note the start-up pressure and flow. A lower start-up is a good indication of the RJH mechanical efficiency and hence less mechanical losses through the machine. When evaluating input values the following example might occur: RJH 1 discharge pump: 100 PSIG inlet to RJH: 95 PSIG nozzle entrance: 75 PSI P across machine: 20 PSI RJH 2 discharge pump: 100 PSIG inlet to RJH: 95 PSIG nozzle entrance: 90 PSI P across machine: 5 PSI Figure 8 In this case RJH 2 with it s lower P would result in a more efficient transfer of energy. It does not necessarily mean that RJH 2 would offer an overall better cleaning ability over RJH 1 as number other factors must be considered. 8 Machine and nozzle design. The internal design of the machine and nozzles has a direct effect on achieving laminar flow when the fluid exits the nozzle as the jet stream. Laminar flow will result in a high density jet-stream with longer distance and impact capabilities resulting in the reduction of cleaning devices, flow requirements, and enhancing the ability to clean shielded areas. The more turbulence created within the cleaning device, the more difficult the task of achieving optimized laminar flow values. Within an RJH; turbulence is created but can be minimized with proper design criteria. In most all designs turbulence is abated primarily within the nozzle hub (Figure 10) and the nozzle (Figure 9). In the case of smaller nozzle designs (Figure 11) little to no turbulence reduction will be achieved. This nozzle body (Figure 10) employs a tangential offset design as opposed to 180 opposite angles. This allows for reduction of turbulence prior to nozzle entry. The nozzle (Figure 9) employs a tubular bundle or flow straightener to further reduce turbulence and hence improve laminar flow values. Figure 10 Figure 11 Figure 9

9 Tank Cleaning Technology Today, the two most common gear mechanisms used in a Rotating Jet-Head are the Worm Wheel and Planetary Gear. Both are effective and proven designs However the external appearance and production requirements are reasonably different. The Worm Wheel Design (Figure 13) will typically use approximately 30%+ fewer parts in the construction of the machine compared to the In- Line or Planetary Gear (Figure 12) methodology and will typically have less pressure drop ( P) across the machine. However, externally the bottom of the machine will require enlargement (bell shape) to allow for a horizontal shaft in the process of transferring torque to the drive mechanism. As a result, the Planetary or In-Line Gear design allows for a smaller profile taking on a cylinder type of construction and many times reduces the size opening required for entry of the RJH in to the tank. Figure 12 The machine designs shown in Figure 13 and Figure 12 are considered pre-programmed machines. In short this means that a given cleaning pattern will be developed for a given XYZ location within the tank being cleaned. Depending upon the gear ratio of the Fixed Gear (the gear attached to the inlet connection) and the moving gear typically the one attached to the hub a set pattern matrix will be developed within the tank. For example; should the fixed Gear employ 65 teeth compared to the hub gear that has 63, it will take 65 axial revolutions to make one complete pattern. After the 65th revolution, and for a given XYZ location within a tank, the pattern matrix will begin all over again tracing back over where it originally began. The pattern matrix of a two nozzle for both a 65/63 and 45/43 gear ratio can be seen below in Figure 14. Figure 13 9 Figure 14

10 Tank Cleaning Technology Programmable Tank Cleaning Machines typically will use a single nozzle design; similar that seen in Figure 15 below. The cleaning patterns are mechanically programmed to start at a given point in the tank and indexed based on a chosen degree inclination per revolution. Figure 15 A computer controlled tank cleaning machine does exist today in the form of a product called the CyberJet. The cleaning jet, which takes the form of a single nozzle machine with retractable down pipe, is controlled by servos that operate via software working from a geometrical representation of the tank being cleaned. See Figure 16 for a visual representation of this device. 10 Figure 16

11 Tank Cleaning Technology 04 - Cleaning Dynamics - The Science of Tank Cleaning Jet Peripheral Velocity - JPV (RJH Devices) The peripheral speed at which the jet-stream is traveling at the farthest distance from the device is a critical factor, particularly in larger or more difficult to clean tanks. See the formula in Figure 17 and illustration in (). Figure 17 Figure 18 This is the most critical factor to consider when selecting and applying an RJH to a given tank cleaning requirement. As a general rule, the following peripheral speeds should be observed: Maximum impact requirements 0.5 to 1.5 feet/second Standard impact requirements 1.5 to 5.0 feet/second Low impact requirements 5.0 to 8.0 feet/second Good washing and rinsing requirements 8.0 to 12.0 feet/second Good wetting requirements feet/second As the speed of the jet-stream increases, the duration time of the jet on the surfaces is reduced. Additionally, the jetshear becomes more prevalent. This serves to degrade the jet-stream and reduce its impact and distance abilities. Jet Density + Velocity = Impact. The density of the jet is controlled by the volume of fluid in the jet and to an extent by the specific gravity of the cleaning media. Velocity is relative to the fluid pressure upon entrance to the nozzle and the achievement of adequate laminar flow upon exiting the nozzle. As we are dealing with a liquid, too great of a jet velocity will serve to degrade the jet-stream prematurely. For example, a pressure of 150 PSI at the nozzle entrance where surface impact is 30 feet from the cleaning device will result in a higher impact than that of 400 PSI at the nozzle. Correspondingly, as the surface becomes closer to the device, impact values will normally increase and higher pressure values at the machine will become more efficient. 11

12 Tank Cleaning Technology Locating The Cleaning Device Placement of the Rotating Jet-Head is not accomplished in the same way as placement of the Rotating Spray-Head or disc. The rotating sphere or disc is positioned in much the same way as the static devices. Although these cleaning devices overcome distance and impact limitations imposed by static devices, it is advantageous to benefit from the cascading effect when installed in the upper portion of the tank or vessel. When determining the position of the rotating jethead, a geometrical study of the host vessel is recommended. Placeent Drawing - Profile View Figure 19 Figure 20 Placeent Drawing - Pla View Figure 22 Figure As the rotating jet-head overcomes limitations of the other devices mentioned, an improper location can result in less than satisfactory results. A study of the jet-stream impact angles and deflection requirements should be made. In doing this the number of units, time, and flow rates required to accomplish the desired cleaning can be optimized. See Figure 19, Figure 20, Figure 22 and Figure 22.

13 Tank Cleaning Technology Validation of Cleaning Device Operation Validation of operation for static devices and rotating spheres or discs are for the most part limited to the monitoring of flow meters, pressure gauges, or ultrasonics. It is difficult to validate that all the ports of a spray ball are clear or that a rotating sphere or disc is in rotation. Visual inspection by means of a sight glass is a reasonably good method. However, in addition to the sight glass method, a rotating jet-head can have its operation validated by the rotation of the jet impinging upon a pressure sensor (See Figure 23). This signal can then be interpreted in various ways, subject to the facility's requirements. Figure 23 13

14 Tank Cleaning Technology Selection Of The Appropriate Cleaning Device The selection of the appropriate cleaning device can involve a number of factors. However, if due consideration is given to the application, the process can be quite simple. When selecting the cleaning device consider the following with regards to the application at hand: Dimensions and internal structures of the tank or process vessel? The size and number of internal structures of the tank or process vessel will be a major factor in determining the type and quantity of devices required. Type of surfaces to be cleaned? Electropolished stainless steel and glass lined vessels are far easier surfaces to clean than carbon steel or certain types of coated tanks. The condition of the lining can also be a factor. This is due to the frictional resistance of the surface to the cleaning media and its ability to absorb the product. Are sanitary conditions required? Sanitary cleaning devices, in most cases, are more costly and will utilize more flow than a device that does not consider this requirement. If you require a 100% self-washing device, make it known in your cleaning design. What openings are available for the installation of the cleaning device? In the case of new equipment, this consideration is more flexible. A review of the vessel design can be made prior to construction and the cleaning requirements determined. Installation is made easier and usually less costly. However, in the case of existing equipment, the desired location for the cleaning device may not be available. This will have a bearing on the device selected and its operating parameters. What percentage of shadow 4 areas are acceptable? At present, there are no regulations governing the percentage of shadow areas for any industry other than marine. However, it is a factor that should not be overlooked when selecting the proper cleaning device. This consideration is a principal factor in determining the number of devices to be used, the type, or both. 4 See footnote 1. A shadow area is the same as a shielded area. 14

15 Tank Cleaning Technology Desired cleaning time? As production requirements may be a primary factor, the speed at which the selected device or devices will render the tank or vessel clean, would be a consideration. Reason for cleaning? What required the subject tank or vessel to be cleaned? To prevent cross-contamination, sterilization, preparation for maintenance, product recovery, etc. 5 A portable cleaning device is any device that is placed into the tank or vessel for cleaning then removed once cleaning has been accomplished. The device does not remain in the vessel during process or storage of the product. Is it desired that the cleaning device be permanently installed or portable? 5 The installation assembly and cleaning device can be of different natures if portable rather than fixed placement is desired. For example, you may not normally require the device to be fully selfwashing if it is to be installed only for the cleaning process and then removed. Type of soil to be removed? The device selected is largely influenced by the type and condition of the soil to be removed. As a simple example, consider the removal of methanol verses the removal of latex. The methanol can be removed with simple cascading of the fluid over the surfaces. A spray ball or rotating sphere/disc could be employed, subject to tank size and capacity. However, in the case of the latex you would be cleaning a long time if you used a spray ball or rotating sphere. For latex, it would be more prudent to use a rotating jet-head at the required pressures and flows. Budget considerations; capital cost and operational? The cost of cleaning devices and their associated systems for a given application can cost from $ to $1,000, The purchase of the device is only part of the cost. In many cases, if the proper cleaning system and device are selected, operational savings can result in a favorable return on investment. Operating parameters? Pressure, flow rates, tank/vessel evacuation rates, cleaning media, operating and at rest temperatures of the cleaning device are all considerations in the selection process. These criteria will determine, among others, the construction requirements of the device. 15

16 Tank Cleaning Technology 05 - CIP (Clean In Place) Systems CIP Systems fall predominantly into the following three categories: Single Use/Single Pass Single Use/Recirculatory Multi-Tank Solution Recovery As this is an abridged version of this paper we will not go into the depth required concerning CIP Systems. However, in general it should be understood, that the CIP Systems should never be designed until the cleaning requirements have been determined. It should also be noted that in addition to the cleaning of the lines, valves and other associated wetted areas must be considered. This in many cased could require multi-pumps or multiple pumps to achieve this requirement. On determination of the in-tank cleaning design, the in the CIP design process is the formulation of the P&ID (Piping and Instrumentation Diagram) see (). 16

17 Tank Cleaning Technology 05 - CIP (Clean In Place) Systems Cleaning Validation is the process whereby the desired cleaning is verified by means acceptable and repeatable for the given cleaning requirement. CIP Optimization is the process of streamlining the cleaning process so that operationally the highest level of efficiency is achieved. In brief, cleaning validation is accomplished today by the following means: Sight Time and Temperature Conductivity Plate Counts ATP (Adenosine Tri-Phosphate) Prior to any Cleaning Validation Process; it is generally good practice to validate coverage by means of establishing rinse protocols so as to insure that all surfaces that require cleaning receive the minimal fluid flow requirements. One of the best methods is the Riboflavin Rinse Validation Process. This method employs the spraying of a Riboflavin mixture onto the surfaces to be cleaned and then validating coverage with a long-wave ultraviolet light. On validation of that coverage the prescribed cleaning arrangement is started and at set time intervals checked and recorded until the surfaces are free of the Riboflavin mixture. Riboflavin is readily miscible with water at ambient temperatures and very accurately reveals if fluid flow reaches the required areas of the tank, valves, pipes, and other areas within the tank or process structure. Figure 24 Figure Application of Riboflavin Mixture

18 Tank Cleaning Technology Figure 26 Figure 27 Validation of Coverage with Long-Wave Ultra Violet Light 18 Figure 28 Figure 29 Photos After Rinsing

19 Tank Cleaning Technology Once sufficient rinse coverage is established, validating cleanliness by the taking of a rinse sample can then be considered viable. Conductivity is a reasonable good way to monitor the absence of certain fluids within the rinse water but is limited to those fluids that possess a reasonably good conductivity value. Biologically, one of the best methods is to measure bio-mass using the ATP detection method. All organic matter possesses ATP (Adenosine Tri- Phosphate). When ATP is properly mixed with Lucifern Luciferase a chemical light is produced that can be accurately read and recorded by a properly balanced luminometer. 19

20 CTG TSP1 EU Our products are distributed through the following Pnr Companies PNR America PNR Benelux PNR Italia PNR Asia PNR Czech Republic PNR Mexico PNR Baltic PNR Deutschland PNR U. Kingdom We are moreover represented in the following countries Argentina Australia Austria Canada China Denmark Finland Greece India Indonesia Iran Ireland Japan Korea Nepal Norway New Zealand Pakistan Poland Portugal Singapore Slovenja Spain Sweden Taiwan Venezuela