Plant Layout

now that we have defined process scheme and the process we shall define their location this will also determine the required plant footprint it is the scope of the plant layout discipline this discipline is usually grouped on the piping even though it has a very distinctive role it defines the overall facility layout ie the relative locations of the various plant areas such as process utility and administrative buildings it also defines the position of equipment within units the overall facility layout is primarily dictated by safety two means are employed to reduce the risk to the minimum possible level the first one is to adequately select the relative positions of the various plant areas the second one is to provide safe separation distances between these areas properly out and spacing indeed can significantly reduce the consequence of a fire or an explosion an oil and gas facility comprises process units utility units as well as off sites such as storage and offloading fire station control room and office buildings utility units are located away from process units in order that they remain operational in the event of an incident in the process unit manned buildings are located the furthest away from process units and in the location where personnel can easily escape the facility the wind direction has a large influence on the layout of a facility this may be quite surprising for the newcomer but one has to understand that a gas cloud that could originate from a leak source would develop towards the direction where it is blown by the wind and it must not be allowed to reach an ignition source therefore ignition sources must be located a point of possible leak sources ie process units and storage areas there are unavoidable ignition sources in oil and gas facilities they include fired equipment such as furnaces as well as the flare and electrical substations the layout shown here would be an adequate layout for a land facility as you can see the prevailing wind is blowing from the left side the flare has been located crossed wind of process units and the storage tanks have been located down wind of the flare the storage tanks could also be located downhill if the relief of the site so allows once this overall facility layout has been decided the relative location of the various process units must be defined the arrangement of process units within the facility is primarily dictated by safety considerations as well separation distances are kept between units in order to limit the impact of fire or explosion in one unit on the nearby units indeed the radiation level from a fire or the overpressure blood just from an explosion very quickly decreases with distance a separation distance is therefore an effective means to reduce the consequence of a fire or explosion in one unit on the adjacent units each unit is classified in terms of level of hazard the classification depends on the type of fleets handled in the unit the type of process is it a reactive process a reaction where there could be a runaway or not and the level of pressure and temperature once each unit has been classified a separation distance is kept between each two units by the combination of the hazard levels for instance two high hazard units will be separated by 60 meters whereas to moderate hazard units will only require a 15 meters separation distance the overall facility layout is reviewed during the hazard review session has it means hazard identification it looks at the hazards to which the plant could be subject due to its location so due to its environment as well as the hazards that are inherent to the plan due to its process and operations the general plot plan shown here for instance was reviewed during the hazard and the various substances we are marked using different colors during this has its session it was decided that the storage tanks must be relocated furthest away from process units once the overall facility layout has been established layout will define the unit layout this is primarily done according to process requirements the position of equipment is data mined according to their sequence on the process flow diagrams the size is given by process in the process equipment list which shows the dimensions of the equipment which result from the process sizing such sizing nevertheless only concerns vessels rotating equipment and heat exchangers and other types of equipment are not sized by process therefore enquiries to vendors are necessary to obtain dimensions in the case shown here for instance that includes a gas compressor and an air-cooled heat exchanger enquiries will have to be made to vendors of these two equipment the gas compressor and the air-cooled heat exchangers to get dimensions in order for plant layout to be able to produce the unit plug plan note that the dimensions to be obtained from vendors of complex equipment such as packages a turbo compressor package for instance must include the dimensions of auxiliaries for a turbo compressor for instance it must include the size of the air inlet system of the turbine as well as fuel gas conditioning and lube oil conditioning skids the view shown here is the plot plan plan view however process equipment must also be arranged vertically the relative elevation of process equipment is determined by process reasons primarily gravity flow from one equipment to the other in this system for instance which is made of a column a reflux condenser an accumulator and a pump the reflux condenser condenses the gas coming out of the column and the condoms liquid flows to the accumulator where from it is pumped back to the column gravity flow is required between the condenser and the accumulator while the pump needs to be located below the reflux accumulator with sufficient head so that it won't cavitate a stacking of equipment such as the one shown here is required the condensers are located above the accumulator which itself is located above the pumps similarly to what was done for process units separation distances are kept between high risk process equipment only a few equipment are concerned they include high pressure pumps pumping flammable fluids at high pressure high temperature flammable gas compressors and so on a separation distance is kept between these two high risk equipment as per the combination of hazard level for example a distance of 15 meters will be provided between a high hazard reactor and a flammable gas compressor a separation distance is also naturally kept between an open flame furnace and the rest of the facility besides process requirements the equipment layout must take into account the access requirements for operation escape and maintenance these two reactors for example are filled with catalyst every few years the catalyst needs to be replaced therefore an access for vehicles needs to be provided to replace this catalyst shell and tube heat exchangers are subject to frequent maintenance which requires the removal of the tube bundle therefore these heat exchangers have been located on the top level on the top deck of this fpso in order to be accessible by the crane in fact the equipment layout for offshore facilities is strongly determined by maintenance requirements by accessibility for maintenance indeed overhead access with a crane for removal of parts is not feasible offshore as it is on shore as equipment are stacked on several levels therefore parts must be moved by means of monorails to the edge of the platform where they can be picked up by the crane the routing of lines between equipment also impact the position of the equipment enough flexibility must be provided in the routing of the line connecting to equipment so that it's thermal expansion will not result in excessive efforts on the equipment nozzles this is particularly true for rotating machinery as excessive effort so could bring to machinery misalignment space must be provided for operator to access instruments and valves for instance one has to take into account that the operator needs to access the suction and discharge valves on the lines feeding this pump as well as the strainer and any instruments present on these lines one may wonder why minimum of three meters is provided between these two vessels however once the equipment pipes and instrumentation has been modeled one will quickly understand that the three meters was a minimum required this shows that plant layout engineer needs a lot of experience it indeed needs to take into account all the equipment environment even if it is not yet designed and shown in the 3d model allocation of space must be made for all the prompt networks including pipes Gables escape ways firewater Network drainage networks and so on let's look at this on the ground networks consolidated drawing it shows all what is on the ground in a facility you find equipment foundations rainwater collection network including underground pipes catch basins and manholes at changes of direction underground vessels which are drain vessels this one this one connected to drain networks which collect drains from vessels such as this column there are few drain networks open drain closed drain some time they are chemical drains also cables are buried on the ground since it provides mechanical protection and also fire protection so you'll find electrical cables instrumentation cables which are also run on the ground finally you will also find the fire water network which is also buried for mechanical protection and fire protection reasons hence a similar drawing showing all the underground networks has an impact on the facility layout and the equipment location finally economic considerations come into play and this is basically to reduce the lengths of pipes cables pipe racks and so on the deliverables of the plant layout discipline include the general plug plan and the unit plug plan the general plug plan shows the overall plant territory it shows the location of the process and utility units as well as buildings of sights Flair it also shows the connection of the plant with its environment such as access roads and pipelines electrical power grid the unit cut plan shows the positions of equipment within a particular unit the one shown here is typical equipment are arranged on both sides of a central pipe rack the central pipe rack supports the lines from one equipment to the other it also supports the lines from the plant to the unit and from the unit to the plant such as utility lines and process lines battery limit valves are located at the boundary of the unit a periphery crowed with access ways provides easy access for operation maintenance or emergency fixing the position of equipment is a major step in the design to do this the involvement of the plant owner the future operator is necessary therefore a review of the plot plan is organized with the plant owner this review is done in 3d and is called the first or 30% model review the review is called 30% as a this stage only search percent of the lines are modeled these are the main process lines all the lines which are shown on the process flow diagrams the aspects reviewed are primarily the access for operation as well as maintenance operations the purpose of the first or 30% model review is to freeze the plot plan once the first model review with a plant owner has been held and any changes have been incorporated in the unit plot plan it is issued for design IFD this is a major design stage indeed many disciplines require the equipment layout the unit plug plumb to be frozen to start their work it includes piping for the routing of lines structural steel for the design of steel structures civil for the design of foundations and underground networks electrical for the design of the electrical power distribution system instrumentation for the routing of instrumentation cables and safety for the distribution of the fire water nevertheless at this stage the unit plug plan will not be finalized as you remember a number of equipment are designed by vendors such as rotating equipment fired equipment packages heat exchangers the dimensions of these equipment will not be known at the stage of the issued for design plot plan this shows the dimensions that were thought to be that of air blowers a issued for design stage of the plot plan and what they finally wear when the plot plant was issued for construction you see that significant differences can appear between these two revisions of the plot plan receiving equipment vendor general arrangement drawings showing equipment dimensions as well as for packages that include several equipment and skids receiving arrangement drawings from the vendors showing the arrangement and dimensions of all the skids and all the parts of the package is a prerequisite to phrase the plot plan and issue it in issued for construction revision and the issue for construction of the plot plan is a prerequisite for any drawing in any discipline to be issued for construction to site this concludes the presentation of the plant layout discipline thank you for your attention goodbye

Channel: InIPED

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Keywords: Plant Engineering and Design

Id: Vpx2q5RKPcM

Length: 22min 59sec (1379 seconds)

Published: Tue May 31 2016