Title of Invention

"DEVICE FOR MEASUREMENT OF FLOW RATE OF OVERFLASH LIQUID IN CRUDE DISTILLATION COLUMNS"

Abstract

The flow measurement device of the present invention uses a measuring vessel of known internal volume, the said measuring vessel is connected to the crude column by pipes with heat tracing for collecting the overflash liquid and sending it back to the column after measurement, the said pipes do not have any flow restriction and the liquid head required for the flow to take place through this device is very low, wherein the measuring vessel is filled with overflash liquid and temperature probes are used to indicate starting and ending of the filling process and knowing the volume of liquid collected and time elapsed the flow rate of overflash liquid may be estimated very accurately wherein accurate measurement of overflash flow rate enables optimized operation of the crude column.

Full Text

Field of the invention The present invention relates to a device for the measurement of flow rate of overflash liquid in crude distillation columns. The present invention also relates to a crude distillation column provided with a novel device for the measurement of flow rate of overflash liquid therein. Background of the invention Distillation of crude oil is used to obtain a number of useful fractions. Distillation of crude oil is typically carried out in two columns, firstly in an atmospheric column and subsequently in a vacuum column, collectively termed as crude distillation columns. The section of a crude distillation column, where the hot feed enters the column, is called flash zone. The section of the column above flash zone is called wash zone and the section below the flash zone is called stripping zone. All these three sections - wash zone, flash zone and stripping zone, play a very important role in fractionation of crude oil. The hot feed (crude oil) entering the flash zone of crude column is split into a vapour and a liquid fraction. The vapour fraction moves upward and enters the wash zone and comes in contact with a wash liquid flowing downward through the wash zone from the column top. A packing is normally used in the portion of the distillation column comprising the wash zone. In atmospheric column trays may be used. However, in vacuum column packing is always preferred. The trays or packing in wash zone enable the vapour and the liquid phases to intimately contact each other thereby enabling exchange of heat and mass therebetween. The vapour-liquid contact in wash zone serves three purposes. Firstly it de-superheats the vapour coming from the flash zone. This is important for mass transfer process to start between vapour and liquid. Secondly, it washes undesirable contaminants like metals carried by the vapour. This is very important in order to maintain the quality of product streams from the column. Finally, it offers mass transfer between liquid and vapour. This is important for proper fractionation of two adjacent product streams. All these objectives of wash zone operation are satisfactorily met only when the optimum quantity of vapour and liquid phases are flowing through the trays or packing of this section. The vapour flow rate is controlled by splitting of hot crude oil feed into vapour and liquid in flash zone, which, in turn, depends on temperature of the hot feed and pressure of the flash zone. However, the liquid flow rate if controlled purely by the amount of liquid, also known as the wash oil, fed to the tray or packing at the top of the wash zone. A useful product stream is drawn from the column just above the wash zone and part of that product oil is diverted to the top of the wash zone as wash oil. Maintaining an optimum rate of wash oil is critical to column fiinctioning. Excess wash oil means loss of product and less wash oil results in sub-optimal functioning performance of the wash zone. In the case of vacuum column operation, this can lead to coke formation in the packed bed. Excessive coking leads to shutdown of the unit resulting in loss for the refinery. The liquid emerging from the bottom of wash zone is called overflash liquid. While the wash oU after passing through the wash zone becomes overflash liquid, the flow rate and composition of the wash oil and the overflash liquid differ since the overflash rate includes entrainment of liquid carried over by the vapour from flash zone of the column. However, there is a direct relation between these two liquid streams. More overflash liquid rate ensures more wash oU rate in relative basis and vice-versa. In crude distillation column flow rate of overflash liquid is measured and the wash oil rate inferred therefrom. Overflash liquid from the bottom of the wash zone flows down to the stripping zone bypassing the flash zone. The stripping zone therefore receives two liquid streams - overflash liquid and liquid from splitting of hot feed. The lighter components are stripped off from this combined liquid stream flowing downward through the frays or packing of stripping zone by using steam introduced at the bottom of stripping zone. The liquid from the bottom of stripping zone is also a useful product and is processed further in downstream units. The rate of overflash liquid determines the rate of this product stream. Therefore, the measurement of overflash liquid rate is important for optimal functioning of stripping zone. In order to measure the overflash liquid rate, the liquid is coUected on a total coUector tray located below the wash zone. The total liquid is taken out from the column, diverted through a flow-measuring device and returned to the column above the stripping zone. Several methods for measurement of liquid flow rate in pipes are known. Several types of flow meters are available for measurement of liquid flow. They can broadly be classified into two categories - differential flow meters, which give instant flow rate such as orifice meter, venturi meter, rotameter, etc., and flow integrator, which gives cumulative flow rate over a specified period of time such as turbine type flow meters. Turbine type flow meters are likely to be more effective for overflash flow measurement because overflash liquid flow is fluctuating in nature and instantaneous value of flow rate is often misleading. Typically for smooth functioning of conventional flow meters, the overflash liquid lines are provided with heat tracing. Heat tracing prevents heat loss to atmosphere and therefore reduces the possibility of congealing of overflash liquid in pipelines and flow meter. An alternative method for measurement of overflash liquid flow rate is to measure it inside the column instead of taking it out. According to this method, overflash liquid from the wash zone bottom tray/collector tray is taken directly to the stripping zone through a pipe located inside the column. The overflash liquid is released in a measuring box located just above the stripping zone top tray/distributor. The overflash liquid from the measuring box flows to the stripping zone top tray/distributor through an orifice of known diameter. Under steady condition, the flow rate of overflash liquid through the orifice in measuring box depends on the level of liquid in measuring box. Knowing the level on liquid in measuring box the flow rate of overflash liquid can be estimated. Since the measuring box is inside the column, the liquid level in it is measured by some indirect method e.g. gamma ray attenuation technique. The disadvantage of conventional flow meters described above is that, in one way or other, they restrict flow passage in pipe. Overflash liquid being very viscous, more so when it is taken out of the column because of its congealing nature, often finds it difficult to flow through those restrictions in flow passage. The hot overflash liquid, when taken out of the column tends to congeal in pipelines, which makes flow measurement by conventional flow meters very difficult. Conventional flow meters usuaUy have flow restriction in the form of orifice plate, venturi throat, rotameter float or turbine blades. Though the situation can be improved to some extent by heating the overflash liquid pipe using heat tracing but the problem remains because of the congealing nature of overflash liquid. Overflash liquid, being very viscous, requires high liquid head for flow to take place in pipe and through flow meters. In crude column the availability of this head is Umited by the height between the bottom tray/coUector tray of wash zone and the top tray/liquid distributor of stripping zone. The over flash liquid flow is not always steady and fluctuating in nature, which interferes with the flow meter reading. Low liquid head makes the flow of overflash liquid through flow meters further difficult, specially outside column even with heat tracing. The flow meter usuaUy stops functioning satisfactorily as liquid starts congealing in dead pockets in and around the flow meter. The restoration of its performance requires thorough cleaning of the flow meter either by isolating and bypassing it or by shutting down the whole column. In both the cases functioning of the whole distUlation unit is disturbed resulting in products of inferior quality, which eventuaUy means loss of refinery profitability. The estimation of flow rate of overflash liquid based on measurement of liquid level in measuring box located inside the column is not accurate because the turbulent condition prevailing inside the column results in fluctuation of level in the box. Indirect measurement of level from outside the column by gamma ray attenuation introduces further inaccuracy in flow rate estimation. Objects of the invention The main object of the invention is to provide a novel device for accurate measurement of flow rate of overflash liquid in atmospheric and vacuum crude distillation column. It is another object of the invention to provide a novel device for the accurate measurement of overflash flow rate in an crude distillationcolumn which works on simple principle of measurement of volume against time. It is another object of the invention to provide a method for the accurate determination of overflash flow rate in a crude distillation column which can accurately measure the flow rate of viscous liquid even for low liquid head and flow fluctuations. It is further object of the invention to provide a novel device for the measurement of overflash flow rate in a crude distillation column wherein problems caused due to congealing of the overflash liquid in flow rate measurement is overcome. It is yet another object of the invention to provide a device for the accurate measurement of overflash flow rate in a crude distillation column wherein cleaning of the flow measurement device can be carried out online without requiring shutdown of the refinery, thereby making the operation of the refinery more economical and efficient. Summary of the invention. The above and other objects of the invention are achieved by the novel overflash flow measurement device of the invention. The flow measurement device of the present invention uses a measuring vessel of known internal volume. The measuring vessel is connected to the crude column by pipes with heat tracing for collecting the oveflash liquid and sending it back to the column after measurement. The pipes do not have any flow restriction and the liquid head required for the flow to take place through this device is very low. Measuring vessel is filled with overflash liquid and temperature probes are used to indicate starting and ending of the filling process. Knowing the volume of liquid coUected and time elapsed the flow rate of overflash liquid may be estimated very accurately. Accurate measurement of overflash flow rate enables optimised operation of the crude column. Accordingly, the present invention provides a device for overflash flow rate measurement in a crude distiUation column, comprising a measuring vessel connectable external to the crude distillation column at an elevation intermediate to wash zone and stripping zone of the crude distillation column, said measurement vessel being adapted to receive an overflash liquid from a bottom tray/collector tray of the said wash zone, said measurement vessel being provided with a top end and a bottom end, a liquid inlet means being provided at the bottom end of the measurement vessel, a first and inlet liquid parameter measurement means being provided connected to the liquid inlet means, an outlet means being provided at the top end of the measurement vessel, a second and outlet liquid parameter measurement means being provided on said outlet means to measure a predetermined parameter of the overflash liquid exiting from said measurement vessel, said measurement vessel being of a predetermined volume. In one embodiment of the invention, a inlet means comprises of an inlet pipe provided with an inlet valve to either stop or allow the entry of the overflash liquid into the measurement vessel. In another embodiment of the invention, the first and inlet liquid parameter measurement means comprises an inlet temperature probe provided on the inlet pipe. In another embodiment of the invention, the outlet means comprises an outlet pipe connected to the measurement vessel adjacent to the top end thereof and provided with an outlet valve to isolate the measurement vessel, if desired. In a further embodiment of the invention, the second and outlet liquid parameter measurement means comprises an outlet temperature probe located on the outlet pipe and adjacent to the measurement vessel. In another embodiment of the invention, the device is isolatable from the crude distillation column by means of a draw off pipe provided with a draw off valve and a bypass pipe-In another embodiment of the invention, the bypass pipe is provided with a bypass valve which is closed when the measurement vessel is online and opened when the measurement vessel is offline. In a further embodiment of the invention, a vapour return means is provided at the top of the measurement vessel and provided with a vapour return valve to allow vapour from measurement vessel to return to the crude distillation column or to isolate the measurement vessel from the column. In another embodiment of the invention, a cleaning liquid inlet means is provided connected to the vapour return means, said cleaning liquid inlet means being provided with a cleaning liquid isolation valve. In yet another embodiment of the invention, the measurement vessel is provided with one or more offline cleaning means. In a further embodiment of the invention, said one or more offline cleaning means comprise one or more holes provided on the vessel with appropriate covering means. In another embodiment of the invention, both the inlet and outlet liquid parameter measurement means comprise gamma ray attenuation meters. The present invention also relates to a crude distillation column provided with an external device for measurement of overflash liquid flow rate. Brief description of the accompanying drawings Figure-1 shows the overall arrangement of the overflash flow rate measuring device with respect to the crude distillation column where the location of wash zone, flash zone and stripping zones in crude column and the layout of pipes connecting the measuring vessel and the crude column are shown. Figure-2 shows the details of the measuring vessel with all inlet/outlet connections and locations of temperature indicators. It also shows the vessel cleaning arrangement. Figure-3 shows a typical pattern of readings by temperature indicators based on which flow rate of overflash liquid is estimated. Detailed description of the invention The present invention relates to a device for measurement of flow rate of overflash liquid in crude distillation column. This is an innovative device, which can handle viscous overflash liquid even under congealing condition outside column. The measurement of flow rate by this device is very accurate. This device does not require frequent cleaning and cleaning, whenever required can be accomplished online without disturbing the normal operation of the column. The device consists of a measuring vessel. The vessel is located outside the crude column at an elevation intermediate to wash zone and stripping zone. The overflash liquid from the bottom tray/coUector tray of wash zone enters the measuring vessel from bottom of the vessel through a pipe connecting the bottom tray/coUector tray and the measuring vessel. A temperature indicator is mounted on this entry pipe nearest to the column. The entry of hot overflash liquid to the measuring vessel is indicated by the rise in temperature in temperature indicator. The liquid exits from the vessel through a pipe connected to the top of the measuring vessel. The hot liquid after entering the vessel gets accumulated in the vessel. As more liquid enters the vessel the level of liquid rises in the vessel until it reaches the exit pipe level. Another temperature indicator is mounted on the exit pi pe and the exit of liquid from the vessel is indicated by the rise in temperature of this indicator. The time difference between the temperature rise indicated by the two temperature indicators is noted. Knowing the internal volume of the vessel and the pipes between the two temperature indicators and time taken by the flowing overflash liquid to fill that volume, the flow rate of overflash liquid is estimated. The exit liquid is returned to the column and is fed on to the top tray/liquid distributor of stripping zone. Whenever the hot overflash liquid enters the measuring vessel, hot vapour is expected to precede the hot liquid. But considering the fact that heat transfer coefficient of vapour is lower than that of liquid, the temperature indicators indicate the entry and exit of hot liquid only and the inaccuracy due to presence of hot vapour is likely to be very less. Design of the vessel is critical because for designing the vessel, estimated flow rate of overflash liquid, height available between wash zone and stripping zone, column pressure and temperature are taken into consideration. An alternative to using temperature indication to mark entry and exit of overflash liquid in measuring vessel, level measurement technique using gamma ray attenuation can be used. Two level indicators are positioned at entry and exit of the measuring vessel and time taken by overflash liquid to fill up the vessel from entry to exit level is noted. Knowing the volume of the vessel the flow rate of overflash liquid is estimated. However, this technique is not very accurate because of fluctuations of liquid level. The measurement of flow rate by the device described in present invention is done offline. From the bottom tray/coUector tray of wash zone, one pipe runs directly to the top tray/liquid distributor of stripping zone bypassing the measuring vessel. The three pipes one for vessel entry, one for vessel exit and one bypassing the vessel, have isolation valves on themselves. During normal operation the overflash liquid flows through the bypass pipe as the valve on it kept open while the other two valves are kept closed. During flow rate measurement, the bypass Une valve is closed and the vessel entry and exit valves are opened. The liquid under such condition flows only through the measuring vessel. There is one more pipe connecting the top of the vessel to the column. This pipe is used to return any accumulated vapour in the vessel back to the column. This avoids any blockage of liquid flow to the measuring vessel due to presence of vapour in the vessel. The vessel is provided with an online cleaning mechanism. A pipe is connected to the top of the vessel through which a light petroleum product like diesel can be put into the vessel. This light petroleum product cleans any congealed liquid or any other deposition in the vessel as weU as connecting pipe lines without disturbing the column operation. The vessel is also provided with hand holes. The hand holes can be opened under shutdown conditions for thorough cleaning of the vessel, in case it is required. The device as detailed in the present invention has been actually tested in a crude vacuum distillation column operating in a refinery. The performance of the device has been found to be satisfactory. The flow rate of overflash liquid measured by using the device is very close to flow rate estimated from simulation calculations based on the operating data. The invention will now be described with reference to the accompanying drawings which are illustrative of the device of the invention and should not be construed as limiting the scope thereof It will be understood from the foregoing and the following description that various modifications are possible to the device of the invention without departing from the scope and spirit thereof Figure-1 shows the overall configuration of the flow rate measuring device for overflash liquid disclosed in the present invention. Hot feed enters the crude distillation column (1) through a feed pipe (2) connected to a feed entry device (3). The feed entry device is located in flash zone (5) of the crude column (1). The hot feed splits into vapour and liquid streams in the flash zone (5). The vapour moves upward and enters the wash zone (4) and the liquid stream moves downward and enters the stripping zone (7). The bottom coUector tray (6) of wash zone (4) coUects the overflash liquid. The overflash liquid is taken out of the column (1) through a overflash draw-off pipe (9). The overflash liquid enters the measuring vessel (13) through an inlet pipe (10) and fills up the measuring vessel (13). The entry of hot overflash liquid to the measuring vessel (13) is indicated by the temperature indicator (16) located on pipe (10). After filling up the vessel (13), the overflash liquid comes out of the vessel (13) through an outlet pipe (11). The exit of hot liquid from the vessel (13) is indicated by the temperature indicator (17). The outlet pipe (11) takes the overflash liquid to column (1) and is fed to the top tray (8) of the stripping zone (7). When the flow rate of overflash liquid is not measured, the measuring vessel (13) is bypassed. The overflash liquid from draw-off pipe (9) goes directly to the vessel outlet pipe (11) through a bypass pipe (12). The vapour accumulated in the measuring vessel (13) is returned to the column (1) through a vapour return pipe (14). A cleaning liquid pipe (15) is connected to the vapour return pipe (14) through which the cleaning oil like diesel is sent to the pipes (9, 10, 11 and 12) and measuring vessel (13). Figure-2 shows the details of the measuring vessel (13) assembly. The measuring vessel (13) has a liquid inlet (10) at bottom. Liquid entry to the vessel (13) is either stopped or aUowed by an inlet valve (20) located on the inlet pipe (10). Inlet temperature probe (16) is located on the inlet pipe (10) very close to the vessel (13) body. The outlet pipe (11) is connected to the vessel (13) near the top. An outlet valve (22) is located on the outlet pipe (11), which is used to isolate the vessel (13), if required. The outlet temperature probe (17) is located on the outlet pipe (II) very close to the vessel (13) body. The overflash liquii from the draw-off pipe (9) either enters the vessel (13) through the inlet pipe (10) or is bypassed to the column (I) through the bypass pipe (12). A draw-off valve (19) is located on the draw-off pipe (9), which isolates the whole device from the column (1), if required. The bypass pipe (12) has a bypass valve (21) on it, which is closed when the vessel (13) is taken in line and is opened when the vessel (13) is bypassed. The vapour return pipe (14) is located at the top of the vessel (131 and a vapour return valve (23) is located on the vapour return pipe (14). The vapour return valve (23) is used either to allow vapour from measuring vessel (13) to return to the column (1) or to isolate the vessel (13) from the column. The cleaning liquid pipe (15) is connected to vapour return pipe (14) and a cleaning liquid isolation valve (24) is located on the cleaning pipe (15). The valve (24) is opened only when the vessel (13) needs to be cleaned by cleaning liquid. The vessel (13) has a hand-hole (18), which may be one or more in number depending on the size of the vessel (13). The handhole (18) is used for thorough cleaning of the vessel (13). Figure-3 shows a graphical representation of readings of temperature indicators (16 and 17) as function of time. The curve (25) shows the reading of temperature indicator (16) and the curve (26) shows the reading of the temperature indicator (17). The mean time of temperature rise in the inlet temperature indicator (16) is marked by the point (27) on time axis. Similarly, the mean time of temperature rise in the outlet temperature indicator (16) is marked by the point (28) on time axis. The difference between these two readings (27 & 28) on time axis gives the time required (29) by the overflash liquid to fill up the known volume ofthe measuring vessel (1*3) from which the flow rate of overflash liquid is estimated. The device described in the present invention is a novel device for measuring flow rate of overflash liquid in crude distillation column. This is a simple device based on the principle of measuring the volume of liquid coUected over a period of time and estimating the flow rate therefrom. The novelty of the device lies in the fact that in spite of its simple working principle it offers an accurate measurement of flow rate of overflash liquid under conditions where conventional flow measuring devices fail to perform satisfactorily. UnUke conventional flow meters, the present device does not have any now restrictions and therefore, the requirement of liquid head for flow to take place through the device is considerably less. This feature of the present device particularly suits flow rate measurement of overflash liquid because in typical crude distillation column the availability of liquid head is not sufficient to drive highly viscous overflash liquid through conventional flow meters offering higher resistance to flow. Overflash liquid is congealing in nature. In the case of flow rate measurement, the liquid tends to congeal in the pipes and flow meters when it is taken out of the column. The present device does not have any flow restrictions and the congealing liquid cannot choke or block flow passages. Further to this the heat tracing provided on pipes and measuring vessel prevents excessive congealing of overflash liquid. This is advantageous over conventional flow meters because the requirement of frequent cleaning of the device is avoided and uninterrupted column operation is achieved. In the present device the overflash liquid is collected in a measuring vessel of known volume and the time of coUection is noted by temperature indication of entering and exiting liquid. The advantage of using temperature indication in the measuring vessel is that it is very sensitive and accurately indicates the entry and exit of hot overflash liquid in the vessel. The present device is most suitable for measurement of fluctuating flow rate of liquid. The advantage of coUecting volume in the measuring vessel over a period of time and then estimating the flow rate is that it eUminates any error due to fluctuation in flow rate, which is likely in the case of overflash liquid. Overall this device measures an accurate averaged flow rate of overflash liquid. The present device has an online cleaning mechanism. The light petroleum oil like diesel is used for cleaning the device in case excessive congealing of overflash liquid takes place in the device. The cleaning can be done online without disturbing the column operation as the cleaning liquid is a petroleum fraction and does not interfere with the normal distlllation process in the column. This reduces refinery down time and improves profitability. However, if the device gets completely choked or blocked by depositions of any kind it can be opened and cleaned after stopping column operation. In the present device as an alternative to using temperature indicators to mark entry and exit of liquid in the vessel, level indicators using gamma ray attenuation technique can be used. The present device can be integrated with control system of the crude column by connecting the output of temperature indicators to it. This enables onUne estimation of flow rate of overflash liquid and the control system can take corrective action, if required and pressure of flash zone. We Claim: 1. A device for overflash flow rate measurement in a crude distillation column (1), comprising a measuring vessel (13) connectable externally to the crude distillation column (1) at an elevation intermediate to wash zone (4) and stripping zone (7) of the crude distillation column (1), said measurement vessel (13) being adapted to receive an overflash liquid from a bottom tray/collector tray (6) of the said wash zone (4), said measurement vessel (13) being provided with a top end and a bottom end, a liquid inlet means (10) being provided at the bottom end of the measurement vessel, characterized in that, a first inlet liquid parameter measurement means being provided connected to the liquid inlet means (10) wherein a temperature probe (16) is located, an outlet means (11) being provided at the top end of the measurement vessel (13), a second outlet liquid parameter measurement means being provided on said outlet means (11) having a temperature probe (17) located on it to measure a predetermined parameter of the overflash liquid exiting from said measurement vessel (13), said measurement vessel (13) being of a predetermined volume such that the flow rate of overflash liquid is estimated by measuring the volume of liquid collected over a period of time using said temperature probes (16 and 17). 2. The device as claimed in claim 1, wherein, the inlet means comprises of an inlet pipe (10) provided with an inlet valve (20) to either stop or allow the entry of the overflash liquid into the measurement vessel (13). 3. The device as claimed in claims 1 and 2, wherein, the first inlet liquid parameter measurement means comprises an inlet temperature probe (16) provided on the inlet pipe (10). 4. The device as claimed in claim 1, wherein, the outlet means comprises an outlet pipe (11) connected to the measurement vessel (13) adjacent to the top end thereof and provided with an outlet valve (22) to isolate the measurement vessel (13), if desired. 5. The device as claimed in claims 1 and 4, wherein, the second outlet liquid parameter measurement means comprises an outlet temperature probe (17) located on the outlet pipe (11) adjacent to the measurement vessel (13). 6. The device as claimed in any of the preceding claims, wherein, the device is isolatable from the crude distillation column (1) by means of a draw-off pipe (9) provided with a draw-off valve (19) and a bypass pipe (12). 7. The device as claimed in claim 6, wherein, the bypass pipe (12) is provided with a bypass valve (21) which is closed when the measurement vessel (13) is online and opened when the measurement vessel (13) is offline. 8. The device as claimed in any of the preceding claims, wherein, a vapour return means (14) is provided at the top of the measurement vessel (13) the said pipe (14) being provided with a vapour return valve (23) to allow vapour from measurement vessel to return to the crude distillation column (1) or to isolate the measurement vessel (13) from the column (1). 9. The device as claimed in claim 8, wherein, a cleaning liquid inlet means (15) is connected to the vapour return means (14), said cleaning liquid inlet means (15) being provided with a cleaning liquid isolation valve (24). 10. The device as claimed in any of claims 1 to 8, wherein, the measurement vessel (13) is provided with one or more offline cleaning means. 11. The device as claimed in claim 10, wherein, the said one or more offline cleaning means comprise one or more holes provided on the vessel (13) with appropriate covering means. 12. The device as claimed in claim 1, wherein, both the inlet and outlet liquid parameter measurement means comprise gamma ray attenuation meters. 13. A crude distillation column (1) provided with an external device as claimed in claim 1 for measurement of overflash liquid flow rate.

Documents:

690-DEL-2003-Abstract-(25-05-2012).pdf

690-del-2003-abstract.pdf

690-DEL-2003-Claims-(19-09-2012).pdf

690-DEL-2003-Claims-(25-05-2012).pdf

690-del-2003-claims.pdf

690-del-2003-Correspondence Others-(01-01-2013).pdf

690-DEL-2003-Correspondence Others-(25-05-2012).pdf

690-del-2003-Correspondence Others-(30-11-2012).pdf

690-DEL-2003-Correspondence-Others-(19-09-2012).pdf

690-del-2003-Correspondence-Others-(26-09-2012).pdf

690-del-2003-correspondnece-others.pdf

690-del-2003-correspondnece-po.pdf

690-DEL-2003-Description (Complete)-(25-05-2012).pdf

690-del-2003-description (complete).pdf

690-DEL-2003-Drawings-(25-05-2012).pdf

690-del-2003-drawings.pdf

690-del-2003-form-1.pdf

690-del-2003-form-18.pdf

690-del-2003-form-2.pdf

690-del-2003-form-3.pdf

690-del-2003-GPA-(26-09-2012).pdf

690-del-2003-gpa.pdf