Abstract:
A method and software for sizing three-phase separators utilizing an iterative approach is provided. The proposed computational method for sizing three-phase separators uses an iterative technique that calculates the optimum vessel dimensions for each service over a range of length to diameter ratios. The method starts with the smallest vessel dimension depending on the service and the selected vessel type and then tries to satisfy all the requirements for vapor/liquid and liquid/liquid separation. The vessel dimensions, i.e., length and diameter, are incrementally changed until all the requirements are met. The method and software are not restricted to any fixed value for the length to diameter ratio. The method and software select the smallest sized three-phase separator required for each service.

Description:
RELATED APPLICATIONS 
     This application is related to and claims priority and benefit of U.S. Provisional Patent Application Ser. No. 60/755,657, filed Dec. 30, 2005, titled “Computational Method For Sizing Three-Phase Separators,” which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to software for, and a method and software for sizing separators. More specifically, the present invention relates to a method and associated software for sizing a three-phase separator utilizing a robust iterative technique. 
     BACKGROUND OF THE INVENTION 
     Three-phase separators are widely used in the petrochemical and oil and gas industries. Engineers often face the problem of designing new separators or verifying the fitness-for-service of existing separators for new service conditions that the separator was not originally designed to handle. Obtaining the smallest vessel size suitable for each service is a time consuming task, which can have a significant impact on the overall cost of projects. 
     One of the most common approaches to sizing three-phase separators is to use a trial and error technique that requires that the designer estimate the separator dimensions. The programs then calculate the maximum allowable velocity of each phase based on the required residence times and usual vapor-liquid separation. It is based on these allowable velocities that the programs decide whether the separator is large enough for operating conditions or design conditions. This prior art approach does not provide the optimum vessel size and requires several attempts by the user to come up with the right combination of diameter and length. Another limitation of these tools is that they mostly work based on a fixed length to diameter ratio. 
     SUMMARY OF THE INVENTION 
     The invention includes a computerized method of sizing a three-phase separator. The method includes the step of providing a computer having a database defining fields. At least a portion of the fields have available preselected sizes for a plurality of predefined standard separators. The fields also have a preselected length to diameter ratio, a minimum required light liquid level for a light liquid phase, and a minimum required heavy liquid level for a heavy liquid phase associated with each of the preselected sizes for the predefined standard separators. The computer also has memory with instructions stored therein. The instructions include a design conditions calculator to calculate preselected design conditions of a fluid entering the predefined standard separator responsive to predetermined values entered by an operator. The instructions also include a separation time calculator to calculate the rising time of the light liquid droplets in the heavy liquid and the settling time of the heavy liquid droplets in the light liquid responsive to a calculated light liquid holdup volume and a calculated heavy liquid holdup volume that are calculated by a holdup volume calculator. The instructions further include a terminal velocity calculator to calculate the terminal velocity of the vapor responsive to the predetermined values entered by an operator. Moreover, the instructions include a required vapor flow area calculator to calculate the required vapor flow area responsive to the terminal velocity of the vapor. Furthermore, the instructions include a minimum dimension retriever that retrieves a smallest available length and a smallest available diameter for a separator from the database responsive to the length to diameter ratios entered by the operator. 
     The method includes the step of an operator entering the predetermined values and a range of length to diameter ratios defined by a minimum length to diameter ratio and a maximum length to diameter ratio. The minimum and maximum length to diameter ratios are defined by the operator. 
     The method includes the step of calculating the design conditions with the design conditions calculator. These calculations are responsive to the predetermined values entered by the operator. The design conditions include a required light liquid holdup volume, a required light liquid surge volume, a required heavy liquid holdup volume, a required heavy liquid surge volume, and a required total light liquid volume. 
     The method includes the step of retrieving from the fields the smallest available minimum diameter and the smallest available minimum length with the minimum dimension retriever responsive to the range of length to diameter ratios entered by the operator. 
     The method includes the step of retrieving from the fields the minimum required light liquid level and the minimum required heavy liquid level. The minimum light and heavy liquid levels are responsive to the smallest available minimum length and smallest available minimum diameter determined based upon the length to diameter ratio. 
     The method includes the step of calculating a volume of the heavy liquid and a volume of the light liquid. The volume of the heavy and light liquids are responsive to the length of the separator, and the diameter of the separator. The volume of the heavy and light liquids are also responsive to the minimum required light liquid level and the minimum required heavy liquid level. The volume of the heavy liquid defines a calculated heavy liquid holdup volume and the volume of the light liquid defines a calculated light liquid holdup volume. The heavy liquid holdup and light liquid holdup volumes being responsive to the dimensions of the separator. 
     The method includes the step of incrementally in :ceasing the minimum required heavy liquid level and repeating or going back to the step of calculating the volume of the heavy liquid and the volume of the light liquid as described above, until the calculated heavy liquid holdup volume is at least as great as the required heavy liquid holdup volume. 
     The method includes the step of incrementally increasing the minimum required light liquid level and repeating or going back to the step of calculating the volume of the heavy liquid and the volume of the light liquid as described above, and continuing the process back to this step, for the calculated light liquid holdup volume to be at least as great as the required total light liquid volume. 
     The method includes the step of calculating the rising time of the light liquid droplets in the heavy liquid and the settling time of the heavy liquid droplets in the light liquid responsive to the calculated light liquid and heavy liquid holdup volumes. 
     The method includes the step of incrementally increasing the length of the separator by a predetermined length incremental step. 
     The method includes the step of confirming the length to diameter ratio based upon the incrementally increased separator length is less than the maximum length to diameter ratio entered by the operator. Then repeating or going back to the step of calculating the volume of the heavy liquid and the volume of the light liquid as described above, and continuing the process back to this step, and replacing the smallest available minimum length with the incrementally increased separator length for the rising time of the light liquid droplets in the heavy liquid to be less than the heavy liquid resistance time and the settling time of the heavy liquid droplets in the light liquid to be less than the light liquid residence time. 
     The method includes the step of incrementally increasing the diameter of the separator by a predetermined diameter incremental step. 
     The method includes the step of confirming the maximum diameter from the database having available sizes for standard separators is at least as great as the separator diameter based upon the incrementally increased separator diameter. There repeating or going back to the step of retrieving the minimum required light and heavy liquid levels as described above, and continuing the process back to this step, And replacing the smallest available minimum diameter with the incrementally increased separator diameter for the length to diameter ratio to be less than the maximum length to diameter ratio, the computer being operable to provide a prompt to the operator that the separator diameter exceeds the maximum diameter from the database having available sizes for standard separators. 
     The method includes the step of calculating the terminal velocity of the vapor responsive to the predetermined values entered by the operator. 
     The method includes the step of calculating the required vapor flow area responsive to the terminal velocity of the vapor. 
     The method includes the step of providing a vapor phase height calculator to calculate a calculated vapor phase height responsive to the separator diameter, the heavy liquid level, and the light liquid level. 
     The method includes the step of providing a vapor phase area calculator to calculate a calculated vapor phase area responsive to the separator length, the separator diameter, and the calculated vapor phase height. 
     The method includes the step of calculating the calculated vapor phase height with the vapor phase height calculator. 
     The method includes the step of calculating the calculated vapor phase area with the vapor phase area calculator. 
     The method includes the step of incrementally increasing the separator length by the predetermined length incremental step. 
     The method includes the step of repeating or going; back to the step of incrementally increasing the separator length followed by confirming the length to diameter ratio as described above, and continuing the prows back to this step, for the calculated vapor phase area to be at least as great as the required vapor flow area. 
     The method includes the step of incrementally increasing the diameter of the separator by a predetermined diameter incremental step. 
     The method includes the step of confirming the maximum diameter from the database having available sizes for standard separators is at least a great as the separator diameter based upon the incrementally increased separator diameter. Then repeating or going back to the step of incrementally increasing the separator length followed by confirming the length to diameter ratio as described above, and continuing the process hack to this step, and replacing the smallest available minimum diameter with the incrementally increased separator diameter fir the length to diameter ratio to be less than tie maximum length to diameter ratio, the computer being operable to provide a prompt to the operator that the separator diameter exceeds the maximum diameter from the database having available sizes for standard separators. 
     The method includes the final step of reporting the length and diameter of the separator. 
     The invention also includes software for placement on memory of a computer to size a three-phase separator. The software has a design conditions calculator to calculate preselected design conditions of a fluid entering a three-phase separator responsive to predetermined values entered by an operator. The software has a separation time calculator to calculate the rising time of a plurality of light liquid droplets in a heavy liquid in the fluid entering the three-phase separator. The separation time calculator also calculates the settling time of a plurality of heavy liquid droplets in a light liquid in the fluid entering the three-phase separator responsive to a calculated light liquid holdup volume and a calculated heavy liquid holdup volume that are calculated by the design conditions calculator. 
     The software also includes a terminal velocity calculator to calculate the terminal velocity of a vapor in the fluid entering the three-phase separator responsive to the predetermined values entered by the operator. The software further includes a required vapor flow area calculator to calculate the required vapor flow area responsive to the terminal velocity of the vapor. Moreover, the software has a minimum dimension retriever to retrieve a smallest available length and a smallest available diameter for a separator from the database responsive to the length to diameter ratios entered by the operator. 
     The software also include a minimum required liquid level retriever to retrieve the minimum required light liquid level and the minimum required heavy liquid level responsive to the smallest available minimum length and smallest available minimum diameter determined responsive to the length to diameter ratio. The software includes a holdup volume calculator to calculate a volume of the heavy liquid and a volume of the light liquid. The holdup volume calculator is responsive to a length and a diameter from the minimum dimension retriever. The holdup volume calculator is also responsive to the minimum required light liquid level and the minimum required heavy liquid level from the minimum required liquid level retriever. The volume of the heavy liquid defining a calculated heavy liquid holdup volume and the volume of the light liquid defining a calculated light liquid holdup volume. 
     The software further includes a vapor phase area calculator to calculate a calculated vapor phase area responsive to the length and diameter of the separator, and a calculated vapor phase height. 
     In a further aspect of the invention, the software can also include a heavy liquid level incrementor to incrementally increase the minimum required heavy liquid level in order for the calculated heavy liquid holdup volume to be at least as great as the required total light liquid volume, and a light liquid level incrementor to incrementally increase the minimum required heavy liquid level in order for the calculated light liquid holdup volume to be at least as great as the required total light liquid volume 
     According to a further aspect of this invention, the software further includes a diameter incrementor to incrementally increase the diameter of the separator by a predetermined diameter incremental step so that increases in the separator diameter are no longer necessary for the length to diameter ratio to be less than the maximum length to diameter ratio. According to this same further aspect of the invention, the software also includes a length incrementor to incrementally increase the length of the separator by a predetermined length incremental step so that increases in the separator length are no longer necessary for the smallest available minimum diameter to at least as great as a total of (1) a minimum vapor height guess value; (2) the minimum required light liquid level minus the minimum required heavy liquid level; and (3) the minimum required heavy liquid level. The length incrementor incrementally increases the length of the separator so that incremental increases in the separator length are no longer necessary for the rising time of the light liquid droplets in the heavy liquid from the separation time calculator to be less than a heavy liquid resistance time and the settling time of the heavy liquid droplets in the light liquid from the separation time calculator to be less than a light liquid residence time. Moreover, the length incrementor incrementally increases the length of the separator so that incremental increases in the separator length are no longer necessary for the calculated vapor phase area from the vapor phase area calculator to be at least as great as the required vapor flow area from the required vapor flow area calculator. 
     The invention provides a method for sizing three-phase separators utilizing an iterative approach. The method starts with the smallest vessel dimension depending on the service and the selected vessel type and then tries to satisfy all the requirements for vapor/liquid and liquid/liquid separation. The vessel dimensions, i.e., length and diameter, are incrementally changed until all the requirements are met. The methods are not restricted to any fixed value for the LAD (length/diameter) ratio and therefore provide the smallest sized three-phase separator required for each service. 
     The methods of the present invention can be used on several different types of separators, including a vertical separator having a baffle, a horizontal separator, a horizontal separator having a boot, a horizontal separator having a bucket and split feed flow, and a horizontal separator having a weir. 
     The proposed computational method for sizing three-phase separators uses an iterative technique that calculates the optimum vessel dimensions for each service over a range of L/D ratios, which is specified by the engineer. It starts with the minimum practical dimensions depending on the type of separator and in each iteration checks all the required criteria with incremented dimensions until all the requirements are met. Most of these requirements are common industry standards which are practiced by major oil companies such as Saudi Aramco. One of the important features of this technique is that it provides the optimum vessel size for an L/D ratio range while all the existing methods work based on fixed values for length and diameter. This means that by choosing a very large range of L/D ratios, the method will calculate the L/D ratio that provides the minimum vessel size for each particular case. 
     The invention provides optimum separator size for each service. The invention works based on an L/D ratio range specified by the engineer, rather than a fixed L/D ratio. The invention calculates the optimum L/D ratio, which results in minimum separator size. The invention ignores and flags out impractical or unrealistic answers. 
     This invention addresses the subject of sizing three-phase separators using a robust iterative technique. It can be applied to separators with most well-known internal types such as weirs, buckets and boots. It may not be used for sizing separators with complicated internals or proprietary devices that enhance phase separation. However, for most engineering evaluations and initial cost estimation purposes, simplified internal structures can be used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above-recited features, advantages, and objectives of the invention, as well as others that will become apparent, are attained and can be understood in detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the drawings that form a part of this specification. It is to be noted, however, that the appended drawings illustrate only preferred embodiments of the invention and are, therefore, not to be considered limiting of the invention&#39;s scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a sectional view of a three-phase horizontal separator designed and sized in accordance with an embodiment of the present invention; 
         FIG. 2  is a sectional view of a three-phase vertical separator designed and sized in accordance with an embodiment of the present invention; 
         FIG. 3  is a sectional view of a three-phase horizontal separator with a weir internal assembly designed and sized in accordance with an embodiment of the present invention; 
         FIG. 4  is a sectional view of a three-phase horizontal separator with a bucket assembly designed and sized in accordance with an embodiment of the present invention; 
         FIG. 5  is a sectional view of a three-phase horizontal separator with a boot assembly designed and sized in accordance with an embodiment of the present invention; 
         FIG. 6  is a schematic diagram of a separator sizing system and method for sizing separators according to an embodiment of the present invention; 
         FIG. 7  is a schematic representation of an input screen for an operator to input operating and design conditions into the separator sizing system of  FIG. 6  according to an embodiment of the present invention; 
         FIG. 8A-8D  is schematic flow diagram of the method for sizing the separators shown in  FIG. 1  when utilizing the system shown in  FIG. 6  according to an embodiment of the present invention; and 
         FIG. 9A-9C  is schematic flow diagram of the method for sizing the separators shown in  FIG. 1  when utilizing the system shown in  FIG. 6  according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-5  show various schematical layouts of separators used in the petrochemical industry to separate heavy liquids, light liquids, and vapors from fluids during refining. One version of a separator  11  is shown in  FIG. 1 . Separator  11  in  FIG. 1  is a horizontal separator typically used for separation of three-phase fluids. Separator  11  includes a separator body  13  that is typically a tubular member situated horizontally with respect to a supporting structure. A pair of separator end caps  15  are attached to separator body  13  to seal the end portions of separator body  13 . Separator  11  preferably includes a separator fluid inlet  17  extending through a sidewall of separator body  13 . In separator  11  shown in  FIG. 1 , fluid inlet  17  extends through an upper wall of separator body  13 . Fluid enters separator  11  through fluid inlet  17  for separation within separator  11 . 
     The separation within separator  11  is typically a static separation. Over time, the heavy liquids found within the fluids settle to the bottom portion of separator  11  while the vapors rise to an upper portion of separator  11 . Between the vapor portion and the heavy liquid portion separating within the fluid are light liquids found within the fluid entering separator  11 . A heavy liquid level is designated by line HL, a light liquid level located between the heavy liquids and the vapor is designated by LL and the vapor is found above light liquid line LL. 
     Separator  11  preferably includes a vapor outlet  19  in fluid communication with the vapor separated from the fluid entering separator  11 . In the version shown in  FIG. 1 , vapor outlet  19  is located through an upper sidewall of separator body  13 . Separator  11  preferably also includes a light liquid outlet  21  in fluid communication with the light liquid separated from the fluid entering separator  11 . Light liquid outlet  21  is preferably positioned through a sidewall of separator  11 , through end cap  15  in the embodiment shown in  FIG. 1 , at an elevation for light liquid outlet  21  to be in fluid communication with the light liquids found in separator  11 . Separator  11  also preferably includes a heavy liquid outlet  23  positioned to receive heavy liquids separating from the fluid entering separator  11 . In the embodiment shown in  FIG. 1 , heavy liquid outlet  23  extends through the lower sidewall of separator body  13  so that heavy liquids settling along the bottom portion of separator  11  can flow out of separator  11  through heavy liquid outlet  23  due to the force of gravity. As will be readily apparent to those skilled in the art, separator  11  shown in  FIG. 1 , depends upon time for the heavy liquids to settle and the vapor to rise in order for separation to occur thereby causing separation across three phases of the fluid entering separator  11 : a vapor phase, a light liquid phase, and a heavy liquid phase. 
     Referring to  FIG. 2 , separator  11  is a vertical separator comprising similar features as that shown in  FIG. 1 . Separator body  13  in the separator shown in  FIG. 2  is aligned vertically with respect to a support structure so that separator  11  is a vertical separator. Fluid inlet  17  extends through a sidewall of separator body  13  while vapor outlet  19  and heavy liquid outlet  23  extend through upper and lower end caps  15 . Light liquid outlet  21  extends through another sidewall of separator body  13  at a position between vapor outlet  19  and heavy liquid outlet  23 . Separator  11  in  FIG. 2  also preferably includes a baffle or weir assembly  25  located within the light liquid level found within separator  11 . As is readily known in the art, weir assembly  25  aids in the separation of heavy and light liquids. Fluid entering fluid inlet  17  slides axially downward beside weir assembly  25  toward a lower portion of separator  11 . After a predetermined amount of time, light liquid droplets found in the heavy liquids are allowed to rise to the light liquid level found in separator  11 , and the heavy liquid droplets found in the light liquid are allowed to settle to the heavy liquid level found in separator  11 . Weir assembly  25  helps to prevent heavy liquid droplets from entering light liquid outlet  21 . 
     Referring to  FIG. 3 , separator  11  is a horizontal separator similar to that shown in  FIG. 1 , however, separator  11  in  FIG. 3  also includes a baffle or weir assembly  25 . Weir assembly  25  extends upward from the lower sidewall of separator body  13  to create a physical barrier that the fluid entering separator  11  will have to flow over in order to reach vapor outlet  19  and light liquid outlet  21 . As is readily appreciated by those skilled in the art, the heavy liquids within the fluid entering separator  11  are not capable of flowing over weir assembly  25  so the heavy liquids flow out of heavy liquid outlet  23  located adjacent weir assembly  25 . The light liquids found in the fluid entering separator  11  flow over weir assembly  25  and collect in a portion of separator  11  segregated from the heavy liquids in the fluid entering separator  11 . The collecting light liquids that have flown over weir assembly  25  exit separator  11  through light liquid outlet  21 . 
     Separator  11  shown in  FIG. 4  is a horizontal separator similar to those shown in  FIG. 1  and  FIG. 3 . Separator  11  in  FIG. 4  preferably includes a bucket assembly  27  medially located between the upper and lower sidewalls of separator body  13 . Bucket assembly  27  includes a generally bucket shaped assembly positioned within the light liquids and above the heavy liquids separated from the fluids entering separator  11 . Bucket assembly  27  also preferably includes a bucket passageway extending axially downward and extending through the lower sidewall of separator body  13  adjacent heavy liquid outlet  23 . The lower extending passage of bucket assembly  27  is in fluid communication with light liquid outlet  21  for light liquids to exit separator  11 . Separator  11  in  FIG. 4  preferably includes a pair of fluid inlets  17  extending through the upper sidewall of separator body  13  at opposite ends of separator  11 . Separator  11  also preferably includes vapor outlet  19  centrally located along the upper sidewall of separator body  13 . Fluid entering separator  11  feeds into separator  11  through both of fluid inlets  17  and collects toward the lower portion of separator  11 . As the liquid level within separator  11  rises, bucket assembly  27  acts as a physical barrier to the heavy liquids within the fluid being in fluid communication with light liquid outlet  21 . The lighter liquids separating from the heavy liquids in the fluid entering separator  11  accumulate and overflow into the center portion of bucket assembly  27  for exiting out of separator  11  through light liquid outlet  21 . Vapor separates from and accumulates above both the heavy and light liquids separated from the fluid entering separator  11  and exits through vapor outlet  19  located at the top sidewall of separator  11 . 
     Referring to  FIG. 5 , separator  11  is another horizontal separator similar to that shown in  FIG. 1 . Separator  11  in  FIG. 5 , however, preferably includes a boot  29  extending downward from the lower sidewall of separator body  13 . Heavy fluid outlet  23  extends from the lower most portion of boot  29 . Heavy liquid separated from the fluids entering separator  11  accumulates within boot  29  before exiting separator  11  through fluid outlet  23 . Light liquids separating from the heavy liquid and vapor exit separator  11  through light liquid outlet  21  extending through end cap  15  at an elevation above the heavy liquid fluid level. Vapor exits separator  11  in  FIG. 5  through vapor outlet  19  positioned through the upper sidewall of separator body  13 . 
       FIG. 6  shows a schematic representation of a separator sizing system  111  designed for selecting the optimum separator size for each of the above described separators  11  shown in  FIGS. 1 through 5 . Separator sizing system  111  preferably includes a processor  211  in electrical communication with memory  311  and a database  411 . Processor  211  is also preferably in electrical communication with a user interface  511  for interaction from a user  513 . As shown in  FIG. 6 , user interface  511  can be a keyboard and monitor assembly for a computer system, however, as will be appreciated by those readily skilled in the art, user interface  511  can be numerous forms of electronic media. For example, a user interface  417  can include, but is not limited to, a mouse attached to a computer, a personal digital assistant (PDA), a cellular telephone with Internet connections, or a touch sensitive screen connected to a computer system having access with a communication network. 
     In the preferred embodiment, software or instructions  313  are preferably stored within memory  311 . Instructions  313  preferably include modules designed to perform specific operations necessary for sizing separators  11 . Instructions  313  preferably include an operating conditions or design conditions calculator  315  to calculate preselected operating conditions and design conditions of the fluid entering separator  11 . The design conditions calculated by design conditions calculator  315  are responsive to values inputted by user  513  into user interface  511  and communicated through processor  211  to memory  311 . Typical design conditions are those that are calculated using basic thermodynamic principles upon entry of such values as specific gravity, density, pressure, and/or temperature of the fluid entering separator  11 . As will be readily appreciated by those skilled in the art, entry of other standard values such as molar weight or mass flow rate can readily be substituted for values in order to calculate design conditions of the fluid entering separator  11 . 
     The typical values or fields ( FIG. 7 ) that are entered by operator  513  for calculations include gas mass flow rate of vapor entering separator  11  with the fluid as well as the gas density of the vapor, light liquid density and light liquid mass flow rate of the light liquids entering separator  11  with the fluid, and the heavy liquid density and heavy liquid mass flow rate entering separator  11  with the fluids. Additional design conditions for initial calculation purposes include the operating temperature, operating pressure, and atmospheric pressure depending upon the location wear separator  11  would be located. 
     Referring back to  FIG. 6 , based upon all these values, various other design conditions can be calculated for example the gas volumetric flow rate, liquid light volume flow rate, liquid light volumetric flow rate, the heavy liquid volumetric flow rate can be calculated by the design conditions calculator  315  responsive to the fields inputted by operator  513 . Values produced from design conditions calculator  313  are preferably transferred through processor  211  to database  411  for storage. Other design conditions include a required light liquid surge volume, a required heavy liquid surge volume, a required light liquid holdup volume, and a required heavy liquid holdup volume. 
     Instructions  313  preferably include a separation type calculator  317  as one of the modules found within instructions  313 . Separation time calculator  317  preferably calculates in a manner known in the art the time required for the heavy liquids to separate from the light liquids and the fluid entering separator  11 . In order to calculate the time required, separation time calculator  317  must calculate both the settling time of the heavy liquid droplets found within the light liquid region of separator  11  and the rising time required for the light liquid droplets found within the heavy liquid region of separator  11 . Both of these values are based upon the principle that over time smaller droplets of the light liquid found within the heavy liquids will eventually rise from the heavy liquid to separate and accumulate with the light liquids found within separator  11 . Similarly, the heavy liquid droplets initially located within the light liquid of the fluid will eventually settle and accumulate with the heavy liquid portion of separator  11 . The separation time calculator  317  advantageously calculates both the settling and rising time required for both of these processes to occur within separator  11 . 
     Another module found within instructions  313  includes a terminal velocity calculator  319 . The terminal velocity calculator calculates in a manner known in the art the terminal velocity of the vapor separating from the light and heavy liquids found within the fluid entering separator  11 . As before, the calculated terminal velocity of the vapor is communicated through processor  211  to database  411  for storage. In the preferred embodiment, another module found within instructions  313  is a minimum dimension retriever  323  and a minimum required liquid level retriever  325 . Minimum dimension retriever  323  and minimum required liquid level retriever  325  advantageously communicates with database  411  which has stored sizes and dimensions, and physical properties of preselected standard separators within the size and dimensions storage field  413 . Minimum dimension retriever  323  is preferably responsive to a minimum length to diameter ratio entered by operator  513  and communicated to memory  311  via processor  211 . Minimum retriever  323  preferably retrieves the minimum length and minimum diameter from the size and dimension database field  413  stored within database  411  for preselected separators having a length to diameter ratio equal to the minimum length to diameter ratio inputted by the operator  513 . Minimum required liquid level retriever  325  advantageously communicates with database  411  to retrieve the minimum required heavy liquid level and minimum required light liquid level for fluids located within a separator  11  with the minimum length and diameter as previously retrieved from minimum dimension retriever  323 . 
     Another module preferably included within instructions  313  is a holdup volume calculator  327 . As is readily appreciated by those skilled in the art, the holdup volume for the heavy liquid and light liquid within the fluid entering separator  11  is the volume of the fluids accumulating before the heavy and light liquids exit separator  11  through their respective liquid outlets  21 ,  23 . Holdup calculator  327  advantageously utilizes standard formulas known in the art for calculating the holdup volume for both the light liquid and the heavy liquid entering and accumulating within separator  11  before exiting through light liquid and heavy liquid outlets  21 ,  23 . Typical holdup volume calculations are dependent upon the design conditions of the fluid entering separator  11  as well as the dimensions of separator  11  as provided from minimum dimension retriever  323 . The holdup volumes calculated by holdup calculator  327  are for comparison with the minimum required holdup volumes calculated by design conditions calculator  315 . 
     A vapor phase area calculator  329  is another module preferably included within instructions  313  of memory  311 . Vapor phase area calculator  329  calculates the vapor phase area remaining within separator  11  based upon the holdup volumes calculated by holdup volume calculator  327 . Therefore, vapor phase area calculator  329  is dependent upon the dimensions of separator  11 . In the preferred embodiment, values calculated by vapor phase area calculator  329 , holdup volume calculator  327 , required vapor flow area calculator  321 , terminal velocity calculator  319 , separation time calculator  317 , and design conditions calculator  315  are communicated through processor  211  to database  411  for storage. Dimensions and liquid levels retrieved with minimum dimension retriever  323 , and minimum required liquid level retriever  325  are also preferably communicated through processor  211  to database  411  for storage. 
     A heavy liquid level incrementor  331  is preferably another module stored on memory  311  as instructions  313 . Heavy liquid level incrementor  331  advantageously increases the heavy liquid level used during calculations by holdup volume calculator  327  responsive to preselected conditions. For example, if the calculated heavy liquid holdup volume calculated from holdup volume calculator  327  is less than the minimum required heavy liquid holdup volume calculated by design conditions calculator  315 , heavy liquid level incrementor  331  incrementally increases the liquid level of the heavy liquids within separator  11  for further calculations. Another module preferably included within instructions  313  is a light liquid level incrementor  333 . Light level incrementor  333  advantageously incrementally increases the minimum light liquid level by a predetermined amount responsive to preselected conditions. For example, light liquid level incrementor  333  incrementally increases the light liquid level used for calculations when the calculated holdup volume of the light liquid within separator  11  calculated by holdup volume calculator  327  is less than the minimum required light liquid holdup volume as calculated by design conditions calculator  315 . 
     Additional modules included within instructions  313  of memory  311  are preferably a diameter incrementor  335  and a length incrementor  337 . Length incrementor  337  advantageously increases the length of separator  11  during calculations responsive to predetermined results. For example, length incrementor  337  can increase the length of separator  11  for calculation purposes when the total height of the vapor plus the height of the light liquid level plus the height of the heavy liquid are greater than the diameter of separator  11  as retrieved by minimum dimension retriever  323 . Preferably, the total height comparison is performed after satisfying that the calculated holdup volume for the light liquids and the calculated holdup volume for the heavy liquids are greater than the minimum required holdup volumes of the light and heavy liquids. An increase in length by length incrementor  337  advantageously reduces the heights for the vapor, heavy liquid, and light liquid within separator  11  so that the dimension required for the heavy liquid, light liquid, and vapor can be less than the diameter as retrieved by dimension retriever  323  for separator  11 . Diameter incrementor  335  advantageously increases the diameter of separator  11  for calculation purposes responsive to predetermined criteria. An example of such predetermined criteria is when the length to diameter ratio of separator  11  following the previous calculations is greater than the length to diameter ratio originally used prior to calculations. Increasing the diameter of separator  11  helps reduce the length to diameter ratio overall for separator  11 . 
     Another module stored within instructions  313  of memory  311  includes the vapor phase height calculator  339 , and a minimum vapor height guesser  341 . Minimum height vapor guesser  341  advantageously provides an initial guess value for the height of the vapor entering separator  11  before calculations are performed by the other modules within instructions  313  as described above. Minimum vapor height guesser  341  can use numerous parameters for supplying a minimum vapor height guess value. For example, minimum vapor height guesser  341  can provide a guess value for the minimum vapor height based upon a percentage of the overall diameter of separator  11 , based upon a preselected value for each predetermined standard separators within database  411  from which dimensions are retrieved by minimum dimension retriever  323 , or based upon the ratio of the vapor to the fluid entering separator  11  through fluid inlet  17 . Vapor phase height calculator  339  advantageously calculates the vapor phase height of the vapor within the fluid entering separator  11  responsive to the dimensions of separator  11  as well as the rising time and settling time of the heavy and light liquids calculated by separation time calculator  317  and design conditions calculator  315 . The vapor phase height calculated by vapor phase height calculator  339  is used in calculating an actual vapor phase area for sensing the viability of separator  11  under the design conditions. 
     An additional module of instructions  313  stored in memory  311  also includes proposed diameter calculator  343 . Proposed diameter calculator  343  advantageously calculates the diameter of separator  11  based upon the height of the vapor, light liquid, and heavy liquid found in the fluid entering separator  11 . Proposed diameter calculator  343  advantageously adjusts the calculated diameter of separator  11  responsive to changes in separator length and separator diameter prior to calculating the holdup volumes. An additional mode of instructions  313  stored in memory  311  is boots, weirs, and buckets adjustor and calculator  344 . Adjustor and calculator  344  advantageously adjusts the calculations to accommodate the presence of boots, weirs, or buckets internally located in the separator like those shown in  FIGS. 1-5 . 
     Database  411  advantageously provides storage fields for various preselected information important for sizing separators  11 . Database  411  preferably comprises a size and dimensions field  413 . The size and dimensions field  413  preferably stores retrievable information pertaining to the sizes and dimensions of preselected standard separators used in the industry for three phase fluid separation. The sizes and dimensions of standard separators can preferably include the length, the diameter, the length to ratio, the minimum required light liquid level, and the minimum required heavy liquid level of each of the preselected standard separators used within the industry. Database  411  also preferably includes a storage field for input fields from operator  415 . As previously described, input fields from operator  415  are used when calculating design conditions by design conditions calculator  315  within memory  311 . Input fields from operator field  415  within database  411  advantageously stores the inputted fields from operator  513  for retrieval by design conditions calculator  315  and other calculators within memory  311  for later calculation interations for sizing separator  11 . 
     Another storage field advantageously stored within database  411  preferably includes calculated values from memory  417 . Values calculated by various instructions  313  within memory  311  are advantageously communicated through processor  211  to database  411  for storage. Calculated values from memory  311  are stored within calculated values from memory field  417  for reporting to operator  513 , or for further calculations upon interations by separator sizing system  111 . 
     Another storage field found within database  411  comprises an updated dimensions from memory field  419  for storing retrievable values for the length and diameter of separator  11  for calculations during interations by separator sizing system  111 . Updated dimensions from memory field  419  preferably retrieves information regarding updated separator dimensions from diameter incrementor  335  and length incrementor  337 . Based upon updated dimensions from memory field  419 , diameter incrementor  335  and length incrementor  337  advantageously increases the length and diameter of separator  11  by increments on top of those incremental steps already added to the length and diameter dimensions of separator  11 . 
     Referring to  FIGS. 8A-8D , the process utilized by separator sizing system  111  is shown in the schematic form of sizing diagram  611 . In operational step  611 , software  313  reads fields and values inputted by operator and stores the values in database  411 . As shown in operational step  613 , the software  313  then calculates design conditions responsive to the input fields. As described above, the calculations performed in operational step  613  are performed by design conditions calculator  315  of software or instructions  313 . In the next operational step  614 , software  313  retrieves the minimum separator length and diameter based upon inputted values for the maximum and minimum length to diameter ratios and vessel type. As discussed above, retrieving of the minimum separator length and diameter for separator  211  is based upon the values retrieved by minimum dimension retriever  323  stored within instructions  313  of memory  311 . 
     After retrieving the minimum separator length and diameter values, the next operational step  615  is for the software to assign the minimum separator length and diameter values for calculations. Afterwards in operational step  616 , the software  313  assumes a minimum height for the vapor phase of the fluid entering separator  11 . As discussed above, the assumption of the minimum height vapor phase is performed by minimum vapor height guesser  341 . 
     After separator sizing system  111  calculates the design conditions responsive to the inputted fields and assigns the dimensions to separator  11  based upon inputted fields, in the next operational step  617 , the software  313  retrieves the minimum heavy liquid and light liquid levels based upon separator length, diameter, and separator type. After retrieving the minimum heavy and light liquid levels, in the next operational step  618 , the software calculates the holdup volumes for the heavy and light liquids based upon the liquid heights and separator dimensions retrieved during operational step  617 ,  616 , and  615 . In operational  619  the software program  311  compares the calculated heavy liquid holdup volume with the minimum required heavy liquid holdup volume based upon the dimensions of separator  11 . In operational step  620  the separator sizing system  111  compares the calculated heavy liquid holdup volume with the minimum heavy liquid volume. If the heavy liquid holdup volume as calculated by operational step  618  is not greater than or equal to the minimum required heavy liquid holdup volume, the software sizing system then proceeds to operational step  621 . If in operational step  620  the calculator holdup volume is less than the minimum heavy liquid holdup volume then the separator sizing system  111  proceeds to operational step  622 . 
     In operational step  621 , after determining that the calculated heavy liquid holdup volume is not greater than or equal to the minimum heavy liquid holdup volume for separator  11 , the software  313  increases the minimum heavy liquid height by a predetermined increment. In the preferred embodiment, the incremental steps for software  313  to incrementally increase the minimum heavy liquid height is preferably six inches. After increasing the heavy liquid height by the predetermined increment by software  313  in process step  621 , the software program  313  compares separator  11  diameter to the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level. The difference of the heavy liquid level from the light liquid level is also known as the height of the light liquid within separator  11 . In process or decisional step  624 , if the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level is greater than the diameter of separator  11 , then the separator sizing system  111  proceeds to letter B which leads to process step  642  ( FIG. 8D ). If the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level is less than or equal to the diameter of separator  11 , then separator sizing system  111  proceeds to process step  625 . In process step  625 , software  313  replaces the previous heavy liquid level with an increased heavy liquid level for calculations. After increasing the heavy liquid level with the increased heavy liquid level for calculations, separating sizing system  111  proceeds back to process step  618  for recalculating the holdup volumes for the heavy and light liquid levels based upon the liquid heights and the separator dimensions, while using the new heavy liquid level for such calculations. The separator sizing system then repeats operational steps  619  and  620 . 
     As mentioned above, when the calculated heavy liquid holdup volume is greater than or equal to the minimum required heavy liquid holdup volume as compared in operational step  620 , software sizing system  111  then proceeds to operational step  622 . In operational step  622 , the software program  313  compares the calculated light liquid holdup volume with the minimum required light liquid holdup volume. A calculated holdup volume is provided by holdup volume calculator  327 . The minimum required light liquid holdup volume is from field  413  within database  411 . The comparison of the calculated light liquid holdup volume and the minimum required light liquid holdup volume is performed within operational step  626 . If the calculated light liquid holdup volume is greater than the minimum required light liquid holdup volume, the software program  313  proceeds to letter A which continues on to operational step  631  ( FIG. 8C ). If the calculated light liquid holdup volume is less than the minimum required light liquid holdup volume then computer software program  313  proceeds to operational step  627 . 
     In operational step  627 , software program  313  increases the minimum light liquid height by a predetermined increment. As mentioned above, the predetermined incremental step is a predetermined value as set within software program  313 . The typical incremental step utilized by software  313  is an increment of six inches. The incremental increase of minimum light liquid height is performed by light liquid level incrementor  333  of instructions  313  stored within memory  311 . After increasing the light liquid level height by the predetermined increment in operational step  627 , software program  313  proceeds to operational step  628 . 
     In operational step  628  software program  313  compares the separator diameter to a total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level. Operational step  628  is similar to operational step  623 . In operational step  629 , if the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level is greater than the diameter of separator  11 , software program  313  proceeds to letter B which is continued on  FIG. 8D  with proceeding toward operational step  642 . If the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level is not greater than the diameter of separator  11 , then this means that the total of the heavy, light, and vapor liquids within separator  11  is capable of being held within the diameter of separator  11 . Upon such a finding in operational step  629 , software program  313  proceeds to operational step  630 , in which software program  313  replaces the previous light liquid level with an increased light liquid level for calculations. After replacing the previous light liquid level as provided by database  411  with the increased light liquid level in operational step  630 , software program  313  proceeds back to operational step  618  for calculating holdup volumes for the heavy and light liquid levels based upon the liquid heights and separator dimensions for separator  211 . After separator sizing program  111  recalculates the holdup volumes for the heavy and light liquid levels in operational step  618 , software program  313  then repeats operational step  619  and  620 . 
     After comparing the calculated heavy liquid holdup volume and the light liquid holdup volumes with the minimum required heavy and light liquid holdup volume in steps  620  and  626 , if the calculated holdup volumes for both the light and heavy liquids were greater than the minimum holdup volumes for the heavy and light liquids, software sizing system  111  proceeds to letter A on  FIG. 8C  which then proceeds to operational step  631  on  FIG. 8C . In operational step  631 , software program  313  calculates the rising time of the light liquid droplets within the heavy liquid of the fluid within separator  11  based upon separator dimensions and liquid levels. The calculations of the rising time for the light liquid droplets in the heavy liquids are performed by separation time calculator  317 . In operational step  632 , software program  313  compares the calculated rising time of the light liquid droplets from separation time calculator  317  with a heavy liquid residence time that is inputted by operator  513  and stored within database  411 . In operational step  633 , if the rising time calculated by separation time calculator  317  is less than or equal to the heavy liquid residence time inputted by the operator  513 , separator sizing system  111  proceeds to operational step  634 . If the rising time of the light liquid droplets within heavy liquid is greater than the heavy liquid residence time inputted by the operator  513 , the separator sizing system  111  proceeds to letter B. 
     In operational step  634 , software program  313  calculates the settling time of the heavy liquid droplets and the light liquid, based upon separator  11  dimensions and the liquid levels within separator  11 . The settling time of the heavy liquid droplets and the light liquid is calculated by separation time calculator  317 . After calculating the settling time of the heavy liquid droplets, software sizing system  111  proceeds to operational step  635 , in which software program  313  compares the calculated settling time of the heavy liquid droplets in the light liquid with the light liquid residence time impeded by the operator  513 . In operational step  636 , if the settling time of the heavy liquid droplets and the light liquid as calculated by separation time calculator  317  is not less than or equal to the light liquid residence time as inputted by operator  513 , then separator sizing system  111  proceeds to letter B on  FIG. 8D . If the settling time of the heavy liquid droplets within the light liquid is less than or equal to the light liquid residence time as inputted by operator  513 , then separator sizing system  111  proceeds to operational step  637 . 
     In operational step  637 , separator program  313  calculates the height of space available for vapor based upon separator  11  dimensions and liquid levels. The calculations performed in operational steps  637  are performed by vapor phase height calculator  339 . After calculating the height of space available for the vapor by vapor phase height calculator  339 , separator sizing system  111  proceeds to operational step  638 . In operational step  638 , software program  313  calculates the area for vapor flow based upon the height of space for vapor and separator  11  dimensions. The calculation of the area for vapor flow is calculated by vapor phase area calculator  329  in instructions  313  of memory  311 . The calculated area for vapor flow calculated by vapor phase area calculator  329  in operational step  638 , is the area available for vapor flow within separator  11 . 
     After separator sizing system  111  calculates the area available for vapor flow with vapor phase area calculator  329  in operational step  638 , separator sizing system  111  proceeds to operational step  639 . In operational step  639 , software program  313  compares the calculated area available for vapor flow (AV) with the minimum required vapor flow area (MinAV). The minimum required vapor flow area is calculated by design conditions calculator  315  and based upon the design conditions inputted by operator  513  and the calculated vapor terminal velocity calculated by terminal velocity calculator  319 . Design conditions calculator  315  also calculates the minimum area required for vapor flow within separator  11 . If the available vapor flow area of separator  11  calculated by vapor flow area calculator  329  is greater than or equal to the minimum flow area required based upon the design conditions, then separator sizing system  111  proceeds to operational step  641 . 
     In operational step  641 , separator  11  can handle the design conditions and requirements for optimal separation of the light liquid, the heavy liquid, and the vapors from the fluid entering separator  11 . Accordingly, in operational step  641 , software program  313  then prints the results of separation sizing system  111  for review by operator  513 . If the calculated area available for vapor flow from vapor phase area calculator  329  is less than the minimum required vapor flow area from design conditions calculator  315 , separator sizing system  111  proceeds to operational step  642 . 
     Operational step  642  is also the operational step proceeded to from letter B corresponding to both operational steps  629  and  624  when the total of the vapor phase height, the heavy liquid level, and the difference of the heavy liquid level from the light liquid level was greater than the diameter of separator  11 . In operational step  642 , software program  313  increases separator  11  length by a predetermined increment. The incremental increase of separator length is performed by length incrementor  337 . After increasing the length of separator  11  with length incrementor  337 , separator sizing program  111  proceeds to operational step  643 . 
     In operational step  643 , software program  313  calculates the length to diameter ratio of separator  11  with the incrementally increased separator length provided by length incrementor  337 . After determining the new length to diameter ratio based upon incrementally increased separator length, software sizing system  111  proceeds to operational step  644 . In operational step  644 , software program  313  compares the length to diameter ratio with the maximum length to diameter ratio inputted by operator  513  and stored in database  411 . In operational step  645 , if the length to diameter ratio as calculated with the incrementally increased length is greater than the maximum length to diameter ratio inputted by operator  513 , separator sizing system proceeds to operational step  647 . If the length to diameter ratio calculated using the incrementally increased length of separator  11  is less than or equal to the maximum length to diameter ratio inputted by operator  513  and stored within database  411 , separator sizing system  111  proceeds to operational step  646 . In operational step  646 , software program  313  replaces the previous separator length with the incrementally increased separator length for calculation purposes and proceeds to letter C. Letter C refers back to letter C on  FIG. 8A , for the separator sizing system  111  to return to operational step  617 . Calculations are then recalculated using the incrementally increased separator length. 
     As mentioned above, if the length to diameter ratio with the incrementally increased separator length is greater than the maximum length to diameter ratio separator sizing system proceeds to operational step  647 . A finding that the length to diameter ratio using incrementally increased separator length is greater than the maximum length to diameter ratio as inputted by operator  517  means that the separator length must be decreased or the separator diameter must be increased in order to remain within the length to diameter ratio boundaries as set by operator  513 . In operational step  647 , software program  313  increases separator diameter by a predetermined increment in order to alter the length to diameter ratio. The software program  313  increases the separator diameter with diameter incrementor  335  of instructions  313  stored within memory  311 . Length incrementor  337  and diameter incrementor  335  preferably increases the length and diameter of separator  11  by six inch increments. However, as will be understood by those skilled in the art, the incremental steps of increasing the length and diameter of separator  11  can be varied as desired. After diameter incrementor  335  increases separator diameter by the predetermined increment, separator sizing system  111  proceeds to operational step  648 . In operational step  648 , software program  313  compares the maximum diameter of available standard separators in database  411  with the incrementally increased diameter provided by diameter incrementor  335 . In operational step  649 , if the incrementally increased diameter of separator  11  is greater than the maximum diameter of the standard separators in database  411 , separator sizing system proceeds to operational step  651 . In separational step  651 , software program  313  suggests using more separators  313  in parallel series for operator  513  to review by using a plurality of separators  313  in parallel, the inlet flow rates of the fluid entering separators  11  can be divided amongst several separators thereby decreasing the length and diameter of separator  11  necessary for proper three phase separation. 
     In operational step  649 , if the incrementally increased diameter of separator  11  is less than or equal to the maximum diameter of standard separators provided in database  411 , separator sizing system  111  proceeds to operational step  650 . In operational step  650 , software program  313  replaces the previous separator diameter with the increased separator diameter from diameter incrementor  335  for further calculations. After substituting the previous separator diameter with the incrementally increased separator diameter from diameter incrementor  335 , separator system  111  proceeds to letter D of  FIG. 8D . Letter D corresponds to letter D found on  FIG. 8A  which sends separator sizing system  111  back to operational step  615 . Separator sizing system  111  substitutes the incrementally increased separator diameter for the diameter used for calculations in the operational steps following operational step  615 . Upon returning to operational step  615  another iteration of calculations is performed by separator sizing system  111 . 
       FIGS. 9A-9C  show a computerized method  711  of sizing separator  11  with separator sizing system  11 , in accordance with the operational steps  611  of  FIGS. 8A and 8D . Method step  713  is providing computer  211  having a database  411  defining fields, and memory  311  with instructions  313  stored therein. The instructions  313  including the design conditions calculator  313 , the separation time calculator  315 , the holdup volume calculator  327 , the terminal velocity calculator  319 , the required vapor flow area calculator  321 , and the minimum dimension retriever  323 . At least a portion of the fields containing available preselected sizes for a plurality of predefined standard separators  413 , the fields also containing a preselected length to diameter ratio  413 , a minimum required light liquid level for a light liquid phase  413 , and a minimum required heavy liquid level for a heavy liquid phase associated with each of the preselected sizes for the predefined standard separators  413 . 
     The instructions  311  including an design conditions calculator  315  to calculate preselected design conditions of a fluid entering the predefined standard separator  11  responsive to predetermined values entered by operator  513 , a separation time calculator  317  to calculate the rising time of the light liquid droplets in the heavy liquid and the settling time of the heavy liquid droplets in the light liquid responsive to a calculated light liquid holdup volume and a calculated heavy liquid holdup volume that are calculated by the design conditions calculator  313 , a terminal velocity calculator  319  to calculate the terminal velocity of the vapor responsive to the predetermined values entered by an operator, a required vapor flow area calculator  321  to calculate the required vapor flow area responsive to the terminal velocity of the vapor, and a minimum dimension retriever  323  that retrieves a smallest available length and a smallest available diameter for a separator from the database responsive to the length to diameter ratios entered by the operator. 
     Method step  715  is entering the predetermined values by an operator  513 , and a range of length to diameter ratios defined by a minimum length to diameter ratio and a maximum length to diameter ratio, the minimum and maximum length to diameter ratios being defined by the operator  513 . 
     Method step  717  is calculating the design conditions with the design conditions calculator  315  responsive to the predetermined values entered by the operator  513 . The design conditions including, but not limited to, a required light liquid holdup volume, a required light liquid surge volume, a required heavy liquid holdup volume, a required heavy liquid surge volume, and a required total light liquid volume. 
     Method step  719  is retrieving from the fields in database  411  the smallest available minimum diameter and the smallest available minimum length with the minimum dimension retriever  323 , responsive to the range of length to diameter ratios entered by the operator  513 . 
     Method step  721  is retrieving from the fields in database  411  the minimum required light liquid level, and the minimum required heavy liquid level responsive to the smallest available minimum length and smallest available minimum diameter determined responsive to the length to diameter ratio. 
     Method step  723  is calculating a volume of the heavy liquid and a volume of the light liquid responsive to the length, the diameter, the minimum required light liquid level, and the minimum required heavy liquid level. The volume of the heavy liquid defining a calculated heavy liquid holdup volume, and the volume of the light liquid defining a calculated light liquid holdup volume. The heavy liquid holdup and light liquid holdup volumes being responsive to the dimensions of the separator. In the preferred embodiment, the heavy liquid holdup and light liquid holdup volumes are calculated with holdup volume calculator  327 . 
     Method step  725  is incrementally increasing the minimum required heavy liquid level and repeating step  723  until the calculated heavy liquid holdup volume is at least as great as the required heavy liquid holdup volume. In the preferred embodiment, method step  725  is performed with heavy liquid level incrementor  331 . 
     Method step  727  is incrementally increasing the minimum required light liquid level and repeating method steps  723 - 725  for the calculated light liquid holdup volume to be at least as great as the required total light liquid volume. In the preferred embodiment, method step  727  is performed by light liquid level incrementor  333 . 
     Method step  729  is calculating the rising time of the light liquid droplets in the heavy liquid and the settling time of the heavy liquid droplets in the light liquid responsive to the calculated light liquid and heavy liquid holdup volumes. In the preferred embodiment, method step  729  is performed by separation time calculator  315 . 
     Method step  731  is incrementally increasing the length of separator  211  by a predetermined length incremental step. In the preferred embodiment, method step  731  is performed by length incrementor  337 . 
     Method step  733  is confirming the length to diameter ratio based upon the incrementally increased separator length is less than the maximum length to diameter ratio entered by the operator  513 . Then repeating steps  723 - 731  and replacing the smallest available minimum length with the incrementally increased separator length for the rising time of the light liquid droplets in the heavy liquid to be less than the heavy liquid resistance time and the settling time of the heavy liquid droplets in the light liquid to be less than the light liquid residence time. 
     Method step  735  is incrementally increasing the diameter of separator  211  by a predetermined diameter incremental step. In the preferred embodiment, method step  735  is performed by diameter incrementor  337 . 
     Method step  737  is confirming the maximum diameter from database  411  having available sizes for standard separators is at least as great as the separator diameter based upon the incrementally increased separator diameter. Then repeating steps  721 - 735  and replacing the smallest available minimum diameter with the incrementally increased separator diameter for the length to diameter ratio to be less than the maximum length to diameter ratio. The computer  211  being operable to provide a prompt to the operator  513  that the separator diameter exceeds the maximum diameter from the database having available sizes for standard separators. In the preferred embodiment, the prompt is provided by increase number of separators suggestor  345 . 
     Method step  739  is calculating the terminal velocity of the vapor responsive to the predetermined values entered by the operator  513 . In the preferred embodiment, method step  731  is performed by terminal velocity calculator  319 . 
     Method step  741  is calculating the required vapor flow area responsive to the terminal velocity of the vapor. In the preferred embodiment, method step  731  is performed by length incrementor  337 . 
     Method step  743  is providing a vapor phase height calculator  339  to calculate a calculated vapor phase height responsive to the separator diameter, the heavy liquid level, and the light liquid level. In the preferred embodiment, vapor phase height calculator  339  is included in instructions  313  of memory  311 . 
     Method step  745  is providing a vapor phase area calculator  329  to calculate a calculated vapor phase area responsive to the separator length, the separator diameter, and the calculated vapor phase height. In the preferred embodiment, vapor phase area calculator  329  is also included in instructions  313  of memory  311 . 
     Method step  747  is calculating the calculated vapor phase height with the vapor phase height calculator  339 . Method step  749  is calculating the calculated vapor phase area with the vapor phase area calculator  329 . 
     Method step  751  is incrementally increasing the separator length by the predetermined length incremental step. In the preferred embodiment, method step  751  is performed by length incrementor  337 . 
     Method step  753  is to repeat steps  731 - 751  above for the calculated vapor phase area to be at least as great as the required vapor flow area. 
     Method step  755  is incrementally increasing the diameter of the separator by a predetermined diameter incremental step. In the preferred embodiment, method step  751  is performed by diameter incrementor  335 . 
     Method step  757  is confirming the maximum diameter from the database  411  having available sizes for standard separators is at least as great as the separator diameter based upon the incrementally increased separator diameter. Then repeating steps  721 - 755  and replacing the smallest available minimum diameter with the incrementally increased separator diameter for the length to diameter ratio to be less than the maximum length to diameter ratio. The computer  211  being operable to provide a prompt to the operator  513  that the separator diameter exceeds the maximum diameter from the database having available sizes for standard separators. In the preferred embodiment, the prompt is provided by increase number of separators suggestor  345 . 
     Method step  759  is reporting the length and diameter of the separator  211 . In the preferred embodiment, method step  759  is reported through the computer or processor  211  and user interface  511  to the operator  513 . 
     Although embodiments of the present invention have been described in the context of a fully functional method, system, and program product of the present invention and/or aspects thereof re capable of being distributed in the form of computer readable medium, media, or means of instructions in a variety of forms for execution on one or more processors such as used in association with various types of computers, including, but not limited to, laptops, personal digital assistants, server computers, administration computers, and various other hardware, software, and/or firmware as understood by those skilled in the art. Also, these embodiments of the present invention can also apply regardless of the particular type of signal bearing media or means used to actually carry out the processing, distributing, or dosing as described herein. Examples of computer readable media or means include: nonvolatile, hard-coded type media such as read only memories (RAMs), erasable, electronically programmable read only memories (EEPROMs), including nonvolatile types, recordable and writable media such as CDs, DVDs, floppy disks, hard drives, and transmission type media such as digital and analog communication links. 
     Those skilled in the art will recognize that many changes and modifications may be made to the system and method of practicing the separator sizing system  111  without departing the scope and spirit of the invention. In the drawings and specification, there have been disclosed embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification.