Saeid Three Phase Separator And Api 521 Flare Kod Design p2c51

Three Phase Separators - Inlet Devices Saeid Rahimi 28-Jan-2013 Introduction For

many, three phase separator sizing is a challenging j o b . This is m a i n l y because o f the number o f process parameters

involved, the variety o f internals and possible internal configurations. In addition, the numbers o f parameters that have to be checked to ensure proper separator sizing are relatively high and sometimes a c o m b i n a t i o n o f these criteria adds to the complexity o f the calculation. That is w h y some believe that there is as much art as there is science to properly deg a (horizontal) three phase separator.

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Nevertheless, 1 believe separator sizing is a simple set o f calculations when you k n o w the basic sizing principals such as gasl i q u i d separation theory, l i q u i d - l i q u i d separation fundamentals and the definitions o f different and their importance. The next step is to obtain the required input data and try to find a size w h i c h satisfies these requirements and criteria. W i t h o u t having the whole picture o f what is g o i n g to be done, any simple exercise can turn into a cumbersome and complex iterative problem. 1 am g o i n g to develop a series o f notes to cover the basics o f three phase separator sizing. This note reviews different types o f inlet devices, their effects on the gas-liquid separation, and sizing and selection details.

Inlet Device Importance A n inlet device should perform the f o l l o w i n g functions: f

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Separate B u l k L i q u i d s

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O f the main functions o f the inlet device is to i m p r o v e the p r i m a r y separation o f l i q u i d from the gas. A n y bulk liquids separated at the inlet device w i l l decrease the separation load on the rest o f the separator and thus improve the efficiency. Good bulk separation w i l l also make the separator operation less sensitive to changes in the feed stream. When mist extractors (mesh or vane pad) are utilized to enhance the l i q u i d droplet separation, the amount o f l i q u i d i n gas in the face o f mist extractor ( l i q u i d loading) adversely affects the performance o f the mist extractor. Therefore using an appropriate inlet device plays a major role in achieving required separation.

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E n s u r e G o o d G a s and L i q u i d Distribution

A properly sized inlet device should reduce the feed stream m o m e n t u m and ensure the d i s t r i b u t i o n o f the gas and liquid(s) phases entering the vessel separation compartment, in order to optimise the separation efficiency. M a l - d i s t r i b u t i o n o f liquid can lead to a large spread in residence times, decreasing the separation efficiency. A l s o a gas mal-distribution at the entrance o f the mist extractor or cyclone deck can locally overload the demister and cause severe carryover.

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Prevent Re-entrainment and Shattering

Re-entrainment o f l i q u i d droplets can be caused by b l o w i n g gas d o w n or across the l i q u i d surface at very high velocities. This phenomenon often occurs when vessels w i t h deflector baffles or h a l f pipes are operated at the higher gas flow rates than what they were designed for. L i q u i d shattering inside the inlet device can also happen i n a vessel w i t h no inlet device or w i t h a deflector baffle when the feed stream's liquid smashes into the plate and is broken up in extremely small droplets. This can create smaller droplets than were present in the feed stream, m a k i n g the separation in the rest o f the separator even harder. Selecting a proper inlet device and f o l l o w i n g c o m m o n design guidelines for setting the distance between the bottom o f the inlet device and highest l i q u i d level inside the vessel should m i n i m i z e this p r o b l e m .

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Facilitate De-foaming

I f the feed stream has a tendency to foam, an inlet device that prevents or even breaks d o w n foam can significantly improve the separation efficiency o f the vessel, reduce the size o f the vessel and the use o f chemicals.

1

Inlet Device Type The f o l l o w i n g section provides some information about different types o f inlet devices. •

No Inlet Device

The simplest form o f vessels has no inlet device on the inlet nozzle.

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Deflector Baffle

Deflector baffles are historically one o f the most c o m m o n types o f inlet devices i n o i l and gas industries before inlet devices w i t h higher separation efficiency become so popular. This device s i m p l y uses a baffle plate in front o f the inlet nozzle to change the direction o f the inlet stream and separate the bulk o f the l i q u i d from the gas. However, an increasing number o f contractors and operators are m o v i n g away from traditional types o f inlet devices towards more advanced designs w i t h higher separation efficiencies.

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90° Elbow

This inlet device is used in the horizontal vessels to direct the inlet stream towards the vessel dish end. L o n g Radius ( L R ) elbows are n o r m a l l y preferred for this purpose and there is no straight run o f pipe downstream o f the e l b o w . However, Short Radius (SR) elbows can be used i f installing LR e l b o w increases the height o f the vapor space. T h e y can be also provided w i t h a straight a m o f pipe w i t h a length equal to t w o times o f the inlet nozzle diameter ( 2 d | ) to direct the feed to the dish end rather than the surface o f l i q u i d inside the vessel and m i n i m i z e the l i q u i d re-entrainment.

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H a l f Open Pipe

H a l f open pipes are the modified versions o f 9 0 ° elbow devices, suitable for both vertical and horizontal separators, w i t h slightly i m p r o v e d bulk l i q u i d removal and reasonable gas distribution. I n this type, a piece o f pipe w i t h a length up to three times the inlet nozzle diameter ( 3 d | ) is welded to the inlet 9 0 ° elbow.

1 fey]/

l a . Horizontal Vessel - T o p E n t r y

l b . V e r t i c a l Vessel

lil

I c . Horizontal Vessel - Side E n t r y

Figure 1 - H a l f Open Pipe Installation Configuration in Horizontal and Vertical Vessels In horizontal vessels, the last section o f the h a l f open pipe should be horizontal, p o i n t i n g opposite to the flow direction in the vessel and w i t h its opening directed u p w a r d (Figure l a ) . In vertical vessels, the last section is closed and its opening is directed d o w n w a r d (Figure l b ) . The same configuration is used when the h a l f open pipe is used for a horizontal vessel w i t h a side nozzle (Figure I c ) .

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Vane Type Distributor

The simplest form o f the vane distributor is the dual vane inlet device (shown in Figure 2.a) w h i c h offers a reasonable flow distribution w i t h l o w shear and pressure drop. In horizontal vessels, it is suited for top entry only. The benefits o f this device compared w i t h simpler deflectors such as deflector plates include reduced agitation and hence i m p r o v e d phase operational performance, more stable level c o n t r o l , and reduced foaming. For liquid slugging applications, usually where there is a long i n c o m i n g flow line, this device provides excellent mechanical strength. The dual vane works by smoothly d i v i d i n g the i n c o m i n g flow into t w o segments using curved vanes lo suit the overall geometry o f the inlet nozzle. The gas phase readily separates and disperses along the vessel, whilst the l i q u i d phase velocity is reduced and the flow directed to the vessel walls where it further disperses and falls into the bulk l i q u i d layer at relatively l o w velocity.

2

Figure 2 - The Different Types o f Vane inlet Devices

For ser\'ices where there is a high gas f l o w relative to the l i q u i d flow, the multi-vane inlet device provides excellent vapour distribution a l l o w i n g a reduced height lo the mass transfer or mist eliminator internals. The vane distributors work by smoothly d i v i d i n g the i n c o m i n g flow into various segments using an array o f curved vanes to suit the overall geometry o f the inlet nozzle and distributor length. T o achieve this effect the vanes start w i t h a wide spacing and gradually reduce the gap, g i v i n g the unit its characteristic tapering shape. It can be installed in both vertical and horizontal (top and side entry) three phase separators. Figure 2.b shows the internal details o f multi-vane inlet distributor. Some vendors have tried to e m p l o y the multivane distributor benefits together w i t h tangential entry ( w h i c h provides considerable centrifugal force) to i m p r o v e the bulk separation. Figure 2.c shows a t y p i c a l type o f vane developed for vertical separators only.

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Slotted Tee D i s t r i b u t o r

The slotted T-shaped distributor consists o f a vertical pipe extended inside the vessel to bring the distributor to the right elevation and a slotted pipe w i t h large holes or rectangular slots (perpendicular to the inlet pipe) ensuring a reduced feed stream velocity and m i n i m i z e d flow turbulence. It can be used in both vertical and horizontal (top entry o n l y ) separators.

The openings o f the slots are usually 120 ° ( ± 6 0 ° ) and towards the dish end and l i q u i d interface in horizontal and vertical vessels, respectively. F i g u r e 3 - Tee distributor

Tangential Inlet W i t h A n n u l a r Ring

Tangential inlet devices have been exclusively developed for vertical vessels. The feed flow radially enters the vessel and accelerates ing through the inlet device, the cyclonic action o f the inlet device helps the liquid droplets flow on the inner w a l l o f the vessel and the stripped gas to flow through the central section o f the inlet device (annular ring) to the gas outlet nozzle. -•••t^^

There are two options w i t h regards to the inlet nozzle arrangements shown in Figure 4. The type depicted in Figure 4a generates higher centrifugal force and slightly better separation efficiency. However, it is not recommended for pressures higher than 5.0 bar due to its construction difficulties at high pressures. Furthermore, both types can have a circular or rectangular inlet nozzle. A larger cross sectional area can be provided when a rectangular ( w i t h height larger than the w i d t h ) nozzle is used.

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Cyclone

The cyclonic inlet device is used in horizontal and some vertical separators where there is a requirement for high momentum dissipation, foam reduction and high capacity. They work on the principle o f enhanced gravity separation by accelerating any incoming stream to a high g-force, w h i c h particularly helps foam to break d o w n into separate liquid and gas phases. U n l i k e most inlet devices that are positioned in the gas phase, the inlet cyclone is partly submerged in the liquid phase. The liquid phases are also separated cenlrifugally through the perimeter o f the cyclone lubes and fall d o w n in lo the bulk liquid layers, whilst the gas forms a central vortex core and escapes through a top outlet hole into the gas space. The m i x i n g elements on top o f the cyclone outlet section usually provide a proper distribution o f the cleaned gas to downstream devices. The device has a high pressure drop associated w i t h it.

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4a. R o u n d E n t r y

4b. Straight E n t r y

F i g u r e 4 - Tangential Inlet E n t r y Arrangements The designs o f the inlet cyclones have evolved over the past decades from short single (conventional cyclones) or dual cyclones into multi-cyclone arrangements (Figure 5). A m a i n characteristic o f the cyclone inlet device is its high f l o w capacity, meaning that more throughput is possible through any given size separator.

Selection Criteria

F i g u r e 5 - M u l t i Cyclone Inlet Device

In order to make a proper selection, you need to k n o w h o w different types o f inlet devices perform in similar conditions. Table I evaluates to what extent they fulfil the functions described earlier in this note. T a b l e 1 - C o m p a r i s o n of Performance of Different Inlet Devices Inlet Device F u n c t i o n s

Separate B u l k L i q u i d s E n s u r e Good G a s and L i q u i d Distribution Prevent Re-entrainment of L i q u i d from the G / L Interface Minimize Droplet Shatter

Facilitate De-foaming

No Inlet

Deflector

Half Open

Baffle

Pipe

Vane Type Distributor

Cyclone

Device

Poor

Poor

Average

Good

Very G o o d

V e r y Poor

V e r y Poor

Average

Good

Good

V e r y Poor

V e r y Poor

Poor

Good

Good

Poor

Very Poor

Average

Very Good

Very Good

V e r y Poor

V e r y Poor

Poor

Average

V e r y Good

It may be concluded f r o m Table-1 that it w o u l d always be necessary to install a sophisticated inlet device such as vane type distributors or cyclones. But, it should be noted that T a b l e - I compares the performance o f different inlet devices in similar conditions. For example, the a b i l i t y o f h a l f open pipe to prevent re-entrainment o f the l i q u i d from G / L interface is poor compared to the vane type distributor when they are installed at the same distance from the gas/liquid interface. However, this deficiency can be i m p r o v e d by p r o v i d i n g enough height between the h a l f open pipe and the interface level. In other words, the weakness o f the inlet device can be compensated i f proper engineering practices are taken into consideration. Another example is the cyclone w h i c h is exceptionally effective in breaking the foam. But the fact is that using the cyclone is particularly essential when the amount o f l i q u i d is considerable. I f the l i q u i d flow rate is not high, most probably it is more reasonable to de-foam the l i q u i d by p r o v i d i n g the adequate residence time (not necessarily much more than what is required for the process operation or l i q u i d - l i q u i d separation) rather than an advanced technology device lo enhance the de-foaming.

Furthermore, performance mentioned in Table I is expected from a correctly designed inlet device. Otherwise, using a w r o n g l y designed cyclone can cause gas b l o w - b y or l i q u i d carry over w h i c h w i l l increase foam formation instead o f stopping it. Or having a high m i x t u r e velocity at the exit o f the annual ring w i l l result in re-entrainment o f the liquid film w h i c h has been already collected on the separator w a l l .

4

In summary, the selection o f the o p t i m a l inlet device differs from case to case. Therefore, it is important to understand how inlet device functions and the effect it has on the separation efficiency o f the rest o f the vessel. The f o l l o w i n g section describes other important parameters i n selecting a proper inlet device.

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Separation Requirements

The first parameter to check is whether a high performance inlet device is required from a process point o f v i e w or not. I f there is no specific separation requirement other than bulk liquid separation and the major portion o f the liquid droplets are relatively large ( t y p i c a l l y larger than 150-200 microns), most probably a vertical K O D w i t h one o f the simplest inlet devices (may be N O inlet device) is sufficient. O n the other hand, using a high performance inlet device is essential in some other applications where the ratio o f l i q u i d to gas i n the feed stream is high and mist extractors (mesh or vane pads) are used to enhance the quality o f gas leaving the vessel. In such applications, the amount o f residual l i q u i d in the gas stream in the face o f the mist extractor plays a major role in achieving the desired separation efficiency in the mist extractor.

Therefore, a high performance inlet device w h i c h

efficiently performs the p r i m a r y separation and u n i f o r m l y distributes the gas across the vessel area prevents the mist extractor f r o m being overloaded w i t h the l i q u i d .

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Therefore, depending on the ratio o f l i q u i d to gas in the feed stream and the selected gas-liquid separation device (permissible l i q u i d loading in the face o f mist extractor) a proper inlet device should be selected.

Otherwise, to take in to the

l i q u i d overloading effect into vessel sizing, the mist extractor K value should be de-rated as pointed out earlier in "Three Phase Separators - T i m e D e f i n i t i o n " . T o calculate the amount o f liquid at the entrance o f the mist eliminator, the feed stream's l i q u i d fiaction can be m u l t i p l i e d by the factors specified in Table 2.

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T a b l e 2 - Efficiency o f Different Inlet Devices for B u l k L i q u i d Removal Tnlet device

N o inlet device

Deflector baffle

H a l f open pipe

Multi-vane

Cyclone

distributor Separation efficiency

<0.5

0.5

0.8

0.95

>0.95

Space and C o s t Considerations In some applications where vessel size is significantly important (such as offshore installations or where the size o f equipment is l i m i t e d by transportation restrictions), reducing the size o f the vessel can be a great advantage. U t i l i z i n g a higher performance inlet device is one o f the methods.

For example, i f the diameter o f vertical K O D mentioned above is

large, installing a h a l f open pipe on Ihe inlet nozzle can cause a great reduction in the length o f the vessel. On the other hand, adding a h a l f open pipe in horizontal vessel w i t h top nozzle may result in a larger vessel diameter as accommodating the h a l f open pipe w i l l need the larger vapor space (the distance between H H L L and the top o f the vessel). Furthermore, it should be noted that theses k i n d o f changes may not always be economically attractive. For example, according to Table 3, where the effects o f different inlet devices on the length o f a vertical vessel have been summarized, replacing the h a l f open pipe w i t h vane distributor in a vertical K O D o f 2000 m m diameter can result in about 0.55D (0.25D in the distance between H L L and inlet device + 0.3D in the distance between the inlet device and top T L ) which is about 1000 m m . Therefore, i f the o n l y reason for this upgrade is to reduce the vessel size, the equipment cost saving due to 1000 m m reduction in the length can be offset by the higher cost o f the inlet device, vendor and contractor engineering costs and delay in procurement, etc.

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Other Parameters

There are some other parameters to look into w h i l e selecting/deg an inlet device for a three phase separator: F l o w regime: annular dispersed and mist flow regimes in the inlet pipe need special attention and inlet devices w i t h higher surface area such as m u l t i v a n e inlet distributor o f tangential inlet w i t h annular ring are recommended when l o w l i q u i d carry over is essential. A l m o s t all inlet devices can be made mechanically appropriate to handle l i q u i d dominant flow regimes such as bubble and intermittent (slug or plug) flow regimes without vibration. The most desired flow regimes in the vessel inlet pipe are stratified (smooth or w a v y ) flow regimes. The design o f inlet p i p i n g to achieve this flow regime should be considered for special services in w h i c h a l o w liquid entrainment rate is required but mist extractors are not allowed due to any reason (i.e. the possibility o f mist pad plugging).

Pressure d r o p : the pressure drop o f the inlet device increases as the number o f internals and changes in Ihe direction o f inlet flow

increases but it usually remains in the order o f a few Pascals. Inlet cyclones usually create higher pressure drop than

other inlet devices, therefore they are not recommended i f the allowable pressure drop is very l i m i t e d . 5

T a b l e 3 - The Effect o f Different Inlet Devices on the Length o f the V e r t i c a l Vessel Inlet device

Inlet device to top T L (KOD)

Inlet device to wiremesh

0.5 D ( m i n 3 0 0 m m )

d,

1.0 D ( m i n 1200mm)

0.7 D ( m m 9 0 0 m m )

0.3 D ( m i n 3 0 0 m m )

2d,

I . 0 D ( m i n 900mm)

0.5 D ( m i n 6 0 0 m m )

0.3 D ( m i n 3 0 0 m m )

di

0.9 D ( m i n 9 0 0 m m )

0.05 D ( m m 150mm)

d| + 2 0 m m

0.6 D ( m i n 6 0 0 m m )

No inlet device Deflector Bafne H a l f open pipe Vane t y p e distributor

Inlet device height (Note 1)

H H L L to Inlet device

0.45

D (min 600iTim)

d, ( m i n 300 m m )

Notes: 1) The inlet nozzle size ( d i ) also varies w i t h the type o f inlet device. U s i n g high performance inlet devices allows the designer to use higher m o m e n t u m for the inlet nozzle sizing. This leads to the reduction in the size o f the inlet nozzle w h i c h directly contributes to the length o f the vertical vessel and can be important (as discussed above) i n the size o f horizontal vessels. Refer lo the nozzle sizing section for further information.

2) The effect o f the inlet device on the size o f a horizontal separator is not that straight forward. O n one hand, using a high performance inlet device (as illustrated in Table 2) can reduce the size o f the vapor space through i m p r o v i n g (not de-rating) the separation efficiency o f mist extractors. On the other hand, the vapor space m a y be governed by other factors, such as m a x i m u m f i l l i n g level or a c c o m m o d a t i n g the gas outlet device (refer to the paper "Three Phase separators - Gas Internals"). For example, some o f the gas outlet devices need vapor space o f at least 4 0 % o f the vessel diameter in w h i c h any inlet device o f ordinary size can be accommodated.

But in any c o n d i t i o n , the vapor space should be sufficiently high to

accommodate the feed inlet device plus m i n i m u m 150 m m between the bottom o f the inlet device and H H L L . See the f o l l o w i n g section for the size o f the inlet device.

F o a m services: cyclones are the o n l y inlet device w i t h proven capability to break the foams. The p r i m a r y purpose o f the inlet cyclone is that o f foam e l i m i n a t i o n inside a separator. M a n y crude oils exhibit moderate or severe foaming tendency and the traditional approach to these problems is through a c o m b i n a t i o n o f oversized equipment using foam breaking packs and chemicals. Nozzle size: using a high performance inlet device enables the designer to use higher m o m e n t u m for inlet nozzle sizing. T h i s can reduce the nozzle size and subsequently the length o f the vessel. It can also be o f great advantage especially when the entire vessel mechanical design can be adversely affected by an extraordinarily large opening.

S o l i d ; a vessel w i t h no inlet device is preferred. Cyclones are not suitable for this ser\'ice as they further accelerate the inlet fluid for separation purpose w h i c h can create an extremely erosive environment. I f an inlet device is inevitable, it should have 1-2 m m extra thiclcness for erosion. Fouling services: Inlet devices w i t h narrow openings such as slotted tee distributors should be used w i t h extra precaution in the fouling services. T h e y are not recommended i f the feed's wax, solid, scale or asphaltene content are high.

Sizine Considerations The f o l l o w i n g section covers the sizing requirements o f the various inlet devices:

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Deflector Baffle

Figure 6 shows the typical dimensions on a deflector baffle.

90° Elbow

The diameter o f the e l b o w should be the same as the inlet nozzle. Figure 7 shows the m i n i m u m height o f vapor space to accommodate

LR and SR elbows. Furthermore, the elbow should be installed as close as possible to the tangent

considering reinforcement and fabrication requirements (150 m m ) .

6

line

A n impingement baffle should be installed opposite to the e l b o w to protect the drum

shell. The

impingement

baffle

diameter

should

be

twice the

elbow

diameter, as o f a m i n i m u m .

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H a l f Open Pipe

Similar to 90 degree the diameter o f the h a l f open pipe is the same as that o f the inlet nozzle. H o w e v e r , the length o f the device is usually 3 times the inlet nozzle diameter ( 3 d | ) out o f w h i c h 2 d | is dedicated to the opening cut.

A h a l f open pipe can also be fitted downstream o f a L R or SR elbow when it is used in horizontal vessels - top entry depending on available vapor space (Refer to Figure 7 for details). For a horizontal vessel, an impingement baffle should be installed opposite to the e l b o w to protect the d r u m shell. The impingement baffle diameter should b twice the e l b o w diameter, as o f a m i n i m u m .

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Vane Type Distributor

In a horizontal vessel, the length o f a multi-vane distributor is between 3 to 5 F i g u r e 6 - Deflector Baffle Dimensions

times the inlet nozzle diameter. For a vertical vessel, the length o f a multi-vane distributor can be as high as the vessel diameter. H o w e v e r , a shorter vane distributor is needed to

accommodate

the required number o f vanes w h i l e o b t a i n i n g a reasonable opening between t w o adjacent vanes.

/

I n other words, a specific number o f vanes should be installed w i t h particular pitch in order to achieve the targeted performance. This can be a trial and error exercise, starting w i t h an assumed length, f o l l o w e d

by specifying the size and

number o f vanes, and finally checking i f this number o f vanes can meet other

150 mm 1.5 dl (LR) or 1.0 dl (SR) 0.5 dl

manufacturing requirements (consult w i t h vendor) in the assumed length or not. 150 mm The height o f the vane is the same as the inlet nozzle. A d d i t i o n a l height for the

LAHH

inlet elbow should be added to the vane distributor height when it comes to determining the m i n i m u m vapor space in horizontal vessels to accommodate inlet device.

the F i g u r e 7 - Inlet E l b o w Dimensions

T

Vane distributors are not recommended i f ^

Vessel diameter is less than 500mm.

>

Inlet nozzle diameter is smaller than 150mm.

>

Inlet nozzle diameter is larger than 1/3 o f the vessel diameter.

T o prevent v i b r a t i o n o f the vanes, special considerations should be given to the design and construction o f the vane distributors when the vane height is in excess o f 8 0 0 m m or exceptionally high f l o w rates are possible or l i q u i d slugging is expected.

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»

--fev-

Slotted Tee D i s t r i b u t o r

The slotted tee distributor can be sized based on the superficial v e l o c i t y o f the inlet fluid in the slot through the f o l l o w i n g equation ( I ) :

Vslot =

MG

Other details and dimensions o f inlet distributor can be calculated using the formulas below:

F i g u r e 8 - T e e Distributor Details

N , M = Q T / ( C 2 X A„„,x v „ J

7

L,,„,= 1 2 0 n d , e e / 3 6 0

QT = QG + Q L

Tee distributor diameter, d,ee. is tlie same as the inlet nozzle size and its length can be calculated by the equation below:

Ldistributor = d,e,+ N„„, X W,,,, + (N,,,,, + 2) X Pitch

Where 0 ; l i q u i d surface tension. m N / m PL: l i q u i d density, kg/m3 PG: gas density, kg/m3 [iQ-. gas viscosity, C , : 7 X 1 0 ' ' ( M e t r i c unit) C 2 : 2 when the f l o w is split between the t w o sides o f the distributor (tee type) and 1 i f a slotted pipe distributor is used. Wsi„,: w i d t h o f slot, 15mm Pitch: the distance between t w o adjacent slots, 2 5 m m

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Tangential Inlet W i t h A n n u l a r R i n g

Inlet nozzle is usually sized by d e t e r m i n i n g the v e l o c i t y required to satisfy the f o l l o w i n g requirements: >

L i q u i d bulk separation

>

Inlet stream m o m e n t u m ( p V ~ )

>

F o a m i n g separation requirement

>

Prevent erosion i f erosive materials are present

Figure

10

-

Tangential

Inlet

with

Annular Ring

The annular r i n g w i d t h is usually the same as the inlet nozzle diameter. The ring height should be 2.5 times the inlet nozzle diameter. The diameter o f the vessel is also l i n k e d w i t h inlet nozzle size and it is the larger o f

>

3.0 and 3.5 times o f mlet nozzle width/diameter for rectangular and circular inlet nozzles, respectively.

>

Vessel diameter required to maintain the gas v e l o c i t y in the vessel cross sectional area b e l o w 3m/sec.

Furthermore, one s o l i d circular baffle w i t h diameter to a l l o w superficial velocity o f 45mm/sec through the annular gap ( w i t h m i n i m u m gap o f 50 m m ) should be installed at least 150 m m above H H L L . Four vertical a n t i - s w i r l baflles should be provided below N L L . These baflles should be extended from 150 m m b e l o w the N L L to the b o t t o m T L . The baffle w i d t h should be about 10% o f the d r u m diameter.

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Cyclone

There are some general guidelines about cyclone inlet device sizing; however, the best approach is to ask the vendor to provide the size o f this device.

Nozzle Design Details A feed stream can enter a horizontal vessel from top or dish ends. When the feed nozzle is on top o f the vessel, the inlet device is usually faced t o w a r d the dish end to make the most use o f the space available in the head cap section.

The diameter o f the inlet nozzle is a function o f the feed flow rate and the pressure. The c r i t e r i o n for nozzle sizing is that the m o m e n t u m o f the feed should not exceed an allowable l i m i t . The m a x i m u m allowable inlet m o m e n t u m can be increased by fitting inlet devices into the inlet nozzle. The f o l l o w i n g table shows the allowable p V ' c r i t e r i o n for different inlet devices w h i c h can be customized based o n the inlet device vendor recommendation. 8

T a b l e 4 - Inlet Nozzle Sizing Criteria Inlet device Pn>V„,\s (pa)

No inlet

Deflector

H a l f open

Multi-vane

Cyclone

device

baffle

pipe

distributor

(conventional)

1,000

1,400

2,100

8,000

1,0000

Multi-cyclone 35,000

Where is the mean density o f the mixture in the feed pipe in k g / m ' Vn, is the velocity o f the mixture in the inlet nozzle in m/s.

Where the inlet feed is practically gas phase, p V " can be increased to 8000 Pa regardless o f the type o f inlet device. Erosional and 8 0 % o f sonic velocity are other limitations that should be met for inlet nozzle design.

Please visit www.linked]n.com/uroups/Chem\vork-3822450

should you have any comments, questions or or feel free

to S.Rahimi(iijgmail.com.

9

APl-521 Flare K O D Design and Even More (Part 1) Saeid R. Mofrad 03-Jan-2014 Introduction A P I 521 provides tlic principles o f flare K n o c k out D r u m ( K O D ) sizing, some guidelines on selecting the type and orientation, number o f inlet/outlet nozzles, internals and the basis for sizing the gas and l i q u i d sections o f the K O D . It also provides the sizing procedure and sample calculation for a typical horizontal K O D . T h o u g h K O D sizing seems to be a simple task, the problem usually rises due to number o f emergency eases for w h i c h the vessel needs to be sized, the variation o f sizing parameters such as l i q u i d and gas f l o w rates, densities and viscosities and K O D pressure and temperature at different emergency cases. Furthermore, the interpretation o f design companies from A P I requirement is different. Specific or additional requirements are sometimes imposed by the Client. For instance, 1 faced some problems recently when in the detail engineering o f a project I tried to set ( f i t ) different l i q u i d levels inside a horizontal flare K O D already sized in the F E E D stage based on A P I standard but not taking the required process c o n t r o l , alarms and trips into .

This note intends to discuss the A P I requirements in detail, review some o f the debates about flare K O D sizing parameters and show h o w to meet the A P I guidelines as w e l l as the actual project and process needs. H o w to specify the K O D sizing cases along w i t h a stepwise sizing procedure and a case study w i l l be discussed in the part 2 o f this paper.

A P I Requirements

''^^n^h

The f o l l o w i n g section outlines the m a i n A P I guidelines for the flare K O D sizing and selection: •

The economics o f d r u m design can influence the choice between a horizontal and a vertical d r u m . I f a large liquid storage capacity is desired and the vapour flow is high, a horizontal drum is often more economical. A l s o , the pressure drop across horizontal drums is generally the lowest o f all the designs. Vertical knockout drums are t y p i c a l l y used i f the l i q u i d load is l o w or l i m i t e d plot space is available. They are w e l l suited for incorporating into the base o f the flare stack.

•

A l t h o u g h horizontal K O D s are available in many configurations, the differences are m a i n l y in h o w the path o f the vapour is directed. The various configurations include the f o l l o w i n g :

•

1. 2.

the vapour entering one end o f the vessel and e x i t i n g at the top o f the opposite end the vapour entering at each end on the horizontal axis and a centre outlet (split entry)

3.

the vapour entering in the centre and exiting at each end on the horizontal axis (split exit)

Configurations 2 and 3 can be used to reduce the drum diameter (but increase the length) for large flow rates and should be considered i f the vessel diameter exceeds 3.66 m (12 ft). Careful consideration should be given to the hydraulics o f split entry configuration to ensure the flow is indeed split in the desired p r o p o r t i o n .

•

The dropout v e l o c i t y i n the d n i m may be based on that necessaiy to separate l i q u i d droplets from 3 0 0 n m to 6 0 0 n m in diameter.

•

The effect o f any l i q u i d contained in the d r u m on

vapour and liquid

reducing the

releases

v o l u m e available

for v a p o u r / l i q u i d

disengagement should be considered in K O D sizing. This liquid may result from: a) Condensate that separates d u r i n g a vapour release, or b) L i q u i d streams that accompany a vapour release. The v o l u m e occupied by the l i q u i d should be based on a release that lasts 20 to 30 minutes. Larger hold-

^

minimum vapour space for dropout velocity liquid hoid-up from safery relief valves and other emergency releases

slop and drain liquid

up volume may be required i f it takes longer to stop the flow. A n y accumulation o f l i q u i d retained from a

prior

release

should

be

added

to

the

liquid

pumpout

indicated in items a) and b) above to determine the available vapour disengaging space.

F i g u r e 1 - F l a r e K n o c k out D r u m Sizing Basis as per A P l - 5 2 1

•

The m a x i m u m vapour release case does not necessarily coincide w i t h the m a x i m u m l i q u i d . Therefore, the K.OD size should be determined tlirough consideration o f both the m a x i m u m vapour release case as w e l l as the release case w i t h the m a x i m u m amount o f l i q u i d .

The overall size o f flare K O D can be specified using the gas droplet settling velocity and l i q u i d hold up time mentioned above. For a vertical vessel, this is quite straight forward as the gas flow rate determines the vessel diameter and l i q u i d h o l d up time is used to calculate the m a x i m u m l i q u i d fill and finally vessel length. However, for horizontal vessel this needs to be done through a trail-and-error calculation.

Liquid Hold-up T i m e In theory, the l i q u i d holdup time o f flare K O D should be higher than the summation o f the time required for the operator to take action and the action to become completely effective. A properly designed K O D should provide enough time for operator to respond and for the pi'ocess system to react in the favorable direction to cease the r e l i e f (i.e. r e l i e f valve to close).

•

A c o m m o n l y accepted time range for the operator action is between 10 to 30 minutes, depending on many parameters including operator experience, the c o m p l e x i t y and extent o f automation and instrumentation o f the plant. For example, i f the process c o n f i g u r a t i o n is pretty simple or few sources can release the l i q u i d to the flare system, i t . w i l l be relatively easy for operator to diagnose the problem, analyse the situation and take proper action. Furthermore, i f the corrective action can be executed from the control room rather than site, it w i l l m i n i m i z e the response time.

•

H o w fast the response becomes fully effective depends on the process dynamics. For example, the effect o f opening an inadvertently closed S D V at the discharge o f a reciprocating pump is sensed by p u m p r e l i e f valve in a relatively short time span i f the blocked valve is near the p u m p . H o w e v e r , it w i l l take several minutes for the discharge pressure to fall and relief valve to start c l o s i n g i f the S D V is at the other end o f a long pipeline. Keep i n m i n d that the relief valve w o n ' t be fully closed unless the pressure falls w e l l below the relief valve set pressure ( t y p i c a l l y 9 3 % o f the set pressure for conventional r e l i e f valve).

Miscellaneous

Volume

A P l - 5 2 1 defines the miscellaneous v o l u m e as any accumulation o f l i q u i d retained from a prior release (from pressure r e l i e f devices or other sources). Then it uses the mysterious value o f 1.89 m3 (500 US gal) o f storage for miscellaneous drainings in a sample calculation w h i c h has become sort o f standard value for many these days, regardless o f the actual plant c o n d i t i o n . The actual intention o f dedicating a part o f the K O D v o l u m e to the miscellaneous liquids becomes clear when we understand few points: •

Flare K O D is sometimes used as the drain d r u m in onshore plants and often in offshore applications. Therefore, most probably small volumes o f l i q u i d d u r i n g normal operation and larger ones during plant overhaul and maintenance

are

drained into the K O D . •

The number o f streams connected to flare are such versatile (control valves, instrument devices' drains and vents, maintenance

vents, s a m p l i n g points, analyzers, pump and compressor seal vents, etc) that it is almost impossible to

guarantee that no l i q u i d w i l l be sent to the K O D d u r i n g normal operation. •

Unless there is very strict plant housekeeping

practices in place (to drain the K O D l i q u i d content every so often),

otherwise the l i q u i d collected d u r i n g normal operation can go unnoticed t i l l the l i q u i d level hits the H H L alarm level. Therefore, in order to specify the miscellaneous volume, a detailed review o f the project drainage philosophy, the sources and amount o f liquid/t\vo phase/condensable gas release to the flare net^vork and finally K O D d u r i n g normal operation, the type o f l i q u i d handling system, its design and operating philosophy is required. The purpose o f this study should be to estimate a practical v o l u m e so that the frequency o f l i q u i d handling operation becomes reasonable d u r i n g normal operation.

L i q u i d Handlint; System The f o l l o w i n g section reviews the design o f various liquid handing systems as they can affect the flare K O D sizing. The l i q u i d collected in the K O D can be evacuated in one o f the f o l l o w i n g ways:

•

Pump The most c o m m o n l i q u i d handling system employs the pump to send the l i q u i d back to the process for repossessing, slops or product tanks, etc. Different instrumentation configurations have been used in past for K O D pumps: 1.

The simplest control configuration w h i c h is usually followed for all rotating machines is to provide a local manual start and stop for the K O D pumps so that site operator does the routine checks to ensure that everything is alright before p u t t i n g the p u m p in service. In this configuration, it is o n l y possible to stop the pump form the

2

control r o o m . Using the pump w i t h local start is in line w i t h the tlare K O D design intent which assumes that KOD

is large enough to accommodate the largest l i q u i d release for 20-30minutes w i t h o u t any need for pump

operation. 2.

For this specific service, some companies prefer to have the start p r o v i s i o n at control r o o m in addition to above.

3.

The pump is automatically started and stopped based on the l i q u i d level in the K O D . W i t h this configuration, the first p u m p starts at the level 1 call First Pump Start Level (FPSL corresponding to H L L - 1 in Table I ) w h i c h is slightly b e l o w H L L . I f the l i q u i d level keeps rising, the second p u m p starts at Second Pump Start Level (SPSL corresponding to F I L L - 2 in Table 1) w h i c h is slightly higher than H L L . Both pumps are stopped at the level called B o t h Pumps Stop L e v e l ( B P S L corresponding to L L L - 1 in Table I ) w h i c h is slightly above L L L .

In all above configurations, i f control system or operator fails to stop the pump due to any reason, both pumps are tripped at L L L L through Emergency Shutdown system ( E S D ) . The pump capacity is usually selected to drain the l i q u i d content o f the K O D in a specified time (typically t w o hours).

Gravity A connection from

the b o t t o m o f K O D to the closed drain

system w i t h a control valve operating w i t h i n a l i q u i d band can be

Siphon

an ideal l i q u i d handling system i f there is an adequate d r i v i n g

Breaker

force (basically differential head between K O D and destination vessel)

for

the

liquid

inside

the

KOD

to

flow.

In

this

configuration, the drain control valve opens at a level slightly below H L L and closes slightly above L L L . A n d finally at L L L L , ESD

system w i l l act to close the drain line shutdown valve in

order to prevent the gas b l o w - b y from K O D to the drain system.

To Drain

Seal Height

The siphon drain ( s h o w n in F i g w e 2) is a type o f gravity drain where the l i q u i d level inside the K O D is maintained by the l i q u i d seal height out o f the vessel w i t h o u t any need for control system. A shutdown valve acting at L L L L however is needed to prevent the gas b l o w - b y . In a properly designed

l i q u i d seal for flare

F i g u r e 2 - G r a v i t y Drain - Siphon Type

K O D , the top o f l i q u i d seal matches the desired l i q u i d level in the vessel and the height (depth) o f seal is specified based on the 175% o f the d r u m ' s m a x i m u m operating pressure. This requirement w i l l restrict the application o f this configuration to very l o w pressure Hares; otherwise the depth o f liquid seal w i l l be too high (most probably below grade) w h i c h outweighs the auto-draining advantage ( s i m p l i c i t y ) o f this configuration.

Heater

,-

: > >

The heater/coil inside the K O D is usually used

because o f t w o reasons; w i n t e r i z a t i o n ' or liquid vaporizer. The

winterization is out o f the scope o f this article but the heater can be used as liquid handling system to vaporize the collected l i q u i d inside the vessel to the stack when there is no system available for d r a i n i n g the l i q u i d into, the liquid is relatively light, and the long term fiaring is not an issue, and at remote locations (i.e. portable flare K O D s ) . However, the effect o f exposing liquid to the high temperature w h i c h can result in coke formation, polymerization, solid deposit, chemical reaction, etc. should be taken into w h i l e selecting this method. The heater can u t i l i z e electricity or any hot

fluid

(stream, hot water or o i l ) as heating m e d i u m depending on the

availability o f heating m e d i u m and the temperature required to vaporize the l i q u i d . It is sized to vaporize the K O D content w i t h i n particular time w h i c h can be as long as 8 hours i f sizing for shorter duration (say 2 hours) considerably increases the heater size/ power consumption. The heater is usually switched on by a gap controller at a level lower than H L L and switched o f f at a level higher than L L L . The heater is usually tripped at L L L L by E S D system. The importance o f t r i p p i n g (he heater before l i q u i d falls below the top o f the heater is vital for the electrical heater where the heater elements it can be damaged as a result o f overheating. The need for t r i p p i n g (closing the heating m e d i u m S D V ) in all other types o f heater should be evaluated on case by case basis. U n l i k e rotating machines, heaters can have start provision from control r o o m w h i c h minimizes the

' keeping the l i q u i d content above a specific temperature to prevent it from becoming an undesirable fluid as a result o f cold weather or auto-refrigeration

3

site intervention and subsequently improves the possibility o f fast start on demand. H o w e v e r , they are usually sluggish systems compared to p u m p or even gravity drain systems as l i q u i d heating and v a p o r i z i n g are relatively slow processes. A K O D equipped w i t h heater should have an additional provision such as truck out connection for evacuating the residual liquid b e l o w L L L L . T a b l e 1 - C o n t r o l and Shutdown Systems' A c t i o n s Level

Action through

Pump

Heater

Gravity

HHLL

Shutdown system

L A H H - plant trip

L A H H - plant trip

L A H H - plant trip

HLL-2

Control system

Start the second pump

NA

NA

HLL

C o n t r o l system

LAH

LAH

LAH

HLL-1

C o n t r o l system

Start the first pump

Svvitch on the heater

Open the drain control valve

LLL-1

C o n t r o l system

Stop both pump

Switch o f f the heater

Close the drain control valve

LLL

C o n t r o l system

LAL

LAL

LAL

Shutdown system

T r i p both pumps

T r i p the heater

Close the drain S D V

LLLL

Note: having separate settings for the control actions than the liquid level alarms is h i g h l y recommended for m o n i t o r i n g the l i q u i d level (especially d u r i n g emergency conditions) and operator intervention because any uncontrolled/unpredicted l i q u i d level rise can risk the plant p r o d u c t i o n ( i f there is a plant shutdown at H H L L ) .

It should be noted that irrespective o f l i q u i d handling system type, the selected control configuration and the level o f automation, no credit is usually g i v e n to the amount o f the l i q u i d that can be drained d u r i n g emergency conditions to reduce the size o f flare K O D because availability and functionality o f liquid handling system can also be adversely affected at this condition. H o w e v e r , i f the draining the l i q u i d is essential, the r e l i a b i l i t y o f power supply and the availability o f destination system to receive the l i q u i d especially d u r i n g emergency c o n d i t i o n (when S D V s are closed) should be ensured.

KOD

Internals

The f o l l o w i n g section reviews the possible internals for the flare K O D , related design considerations and their effects on the size o f K O D : *^

•

Inlet Device In general, a n y t h i n g that can block the relief path is not acceptable on the flare system. In line w i t h this, the K O D inlet nozzle is usually equipped w i t h o n l y simple and robust (properly designed or attached) inlet devices such delleclor baffle, 9 0 ° elbow or h a l f open pipe to direct the i n c o m i n g stream towards the dish end and make the vessel length available for the l i q u i d droplets to settle. Refer to the paper "Three Phase Separators - Inlet Devices" for further details about different inlet devices.

There are some debates about the suitability o f deflector baffle/plate on the inlet nozzle but it is believed that the failure o f the deflector baftle/plate ( w h i c h is a rare case anyway) w i l l not obstruct the f l o w path into and out o f the K O D . Some companies accept using the multi-vane distributor on the inlet nozzle w i t h particular design, fabrication and installation considerations.

The difference between a K O D w i t h and w i t h o u t inlet device is that in the second one the effective length for l i q u i d droplet separation is the distance between the inlet and outlet nozzles centerlines. T h i s can be considerably less than the KOD

actual length considering Ihe large nozzles ( w h i c h are quite c o m m o n in this application) and the nozzle w e l d i n g

requirement (the distance between nozzle neck at tangent line w e l d lines). I n a K O D w i t h the 90 elbows on both inlet and outlet nozzles the full vessel length is practically available for l i q u i d droplet separation. Therefore installing a suitable device on inlet and outlet nozzles can result in substantial reduction i n K O D length. O n the other hand, adding an inlet device can add some limitations on the m a x i m u m l i q u i d fill as discussed in the paper "Three Phase S e p a r a t o r s L i q u i d Levels",

•

O u t l e t Device The choice o f outlet device is much more restricted than the inlet nozzle so that most o f companies d o n ' t even accept the deflector baffle on the outlet nozzle as it can potentially block the flow path once it is dislodged. Therefore, the outlet nozzle is either w i t h o u t any device or w i t h 9 0 ° elbow (this is not possible in split e n t i y and split exit designs).

4

•

G a s - L i q u i d Separation Device Though separation o f l i q u i d droplets in the range o f 300-600 microns through gravity settling is relatively easy, using any gas-liquid separation device such as mist eliminators to reduce the K O D size shall be avoided because o f the potential for blockage from scale or w a x y deposits.

•

L i q u i d - L i q u i d Separation Device K O D s are usually treated as t w o phase separators, however, provisions can be made for water boot i f it is really critical to separate the water from hydrocarbon before further processing. Considering the fact that there is an ample o f residence time in K O D for the gravity l i q u i d - l i q u i d separation, it is hard to believe that a l i q u i d - l i q u i d separation device such as plate pack or coalescing mat w i l l be ever needed in the K O D .

F r o m K O D sizing v i e w p o i n t , using the boot for an absolutely dry K O D , in one hand, may enable the designer to accommodate the l i q u i d levels up to the H L L w i t h i n a small v o l u m e o f the boot and free up the horizontal vessel full cross section area for the l i q u i d droplet separation w h i c h w i l l reduce the vessel diameter and subsequently the total weight and cost o f the K O D . O n the other hand, having boot (especially for the wet K O D s ) can increase the overall elevation o f K O D

inlet nozzle, the entire plant pipe racks carrying the Hare headers and shoot up the plant capital cost.

L i q u i d L e v e l Setting Apart from the l i q u i d hold up time and l i q u i d droplet separation requirements w h i c h determine the overall size o f flare K O D , the f o l l o w i n g considerations shall be taken into in order to address operation and control aspects in K O D size: •

L o w - L o w L i q u i d level ( L L L L ) is the m i n i m u m allowable l i q u i d level inside the K O D . This is the level at w h i c h ESD system stops the l i q u i d draining by tripping/closing the pumps/heater/drain shutdown valve. It is normally specified based on the pump N P S l l , heater submergence depth or the size o f l i q u i d outlet nozzle (size/height o f vortex breaker). This varies from 150mm in gravity drain arrangement to lOOOmm in presence o f an electrical heater (exact value is set based on the heater bundle diameter).

•

L o w L i q u i d Level ( L L L ) is where the l o w level alarm is triggered to warn operator that liquid level is still falling and there is a risk o f gas b l o w - b y . L L L should be 1-2 minutes above L L L L based on the m a x i m u m draining rate, w i t h m i n i m u m o f I OOmm.

•

L L L - 1 is the level at w h i c h pumps/heater/drain control valve is stopped/switched off/closed by the control system. L L L I level should be at least 100 m m above L L L .

•

H L L - 1 is the level at w h i c h the first pump/heater/drain control valve is started/switched on/opened by the control system. H L L - 1 level should be at least 100 m m below H L L .

•

H i g h L i q u i d Level ( H L L ) is where high level alarm is triggered to w a r n operator that despite o f control system action at H L L - 1 the l i q u i d level is still rising and there is a risk o f plant trip. T o accommodate control system actions ( L L L - 1 and H L L - 1 ) , H L L should be at least 3 0 0 m m above L L L i f the l i q u i d is pumped out and 2 0 0 m m above L L L in other arrangements. In order to meet the A P I requirement, the v o l u m e between L L L to H L L should be larger than Miscellaneous V o l u m e too. .

•

H L L - 2 is the level at w h i c h the second pump is started by the control system to increase the l i q u i d discharge rate and prevent h i g h - h i g h level trip. H L L - 2 should be at least 100 m m above H L L . This level does not exist in K O D s w i t h healer (vaporizer) or gravity draining.

•

H i g h - H i g h L i q u i d Level ( H H L L ) is where the upstream process plant is usually tripped, especially i f tripping o f facilities is practical and the risks associated w i t h liquid carryover to the stack are high. It is usually a l l o w e d to depressurize the plant w h e n the K O D level is at H H L L . In line w i t h A P l - 5 2 1 standard, the distance between H L L and H H L L is specified to accommodate the m a x i m u m i n c o m i n g liquid flow rate for 20-30 minutes. The area above H H L L , vapor space, is available for l i q u i d di'oplet separation.

Dead Volume A l t h o u g h the representation o f K O D volumes in A P l - 5 2 1 (Figure 1) indicates that the entire bottom section o f K O D is available for holding the maintenance/miscellaneous drains, in reality part o f this v o l u m e w h i c h is below L L L - 1 w i l l remain always liquid filled. I call this idle v o l u m e the Dead V o l u m e hoping that the new term w i l l help the designer make distinction between miscellaneous and dead volumes and correctly specify the v o l u m e inside the vessel that can be dedicated to the drain system.

5

Post E S D Volume A s mentioned above some companies have hnked the h i g h - h i g h h q u i d level in the Hare K O D w i t h the entire plant shutdown. Then they realized that some o f the equipment (such as compressors

or

reactors) cannot be held in pressurized condition for a long time and needs to be depressurized after

tof

releases

/

minimum vapour space for dropout velocity • /

shutdown. M o r e o v e r , since depressuring is often side, the need emerged;

for new

Emergency

additional l i q u i d

High-High

Liquid

level

and other emergency releases

Level

(EHHL),

Post ESD volume •

liquid liold-up from safety relief valves

associated w i t h l i q u i d condensation on the flare

(emergency volume)

\

slop and drain liquid imiscelianeous volume) dead volume

E H H L L is specified based on the total v o l u m e o f l i q u i d that can reach the t l a i e K O D after plant shutdown.

The

liquid

is

mainly

due

to

the

pumpout

condensation o f vapor released from a particular equipment or part o f the plant that cannot maintained

under

pressure

due

to

be

process,

F i g u r e 3 - Flare K n o c k out D r u m Sizing Basis

operation or safety' considerations.

A c c o r d i n g to the philosophy established f o l l o w i n g this design development:

•

E H H L L is where the upstream plant depressurization is inhibited. I n order to specify the level, further study needs to be conducted to identify the section o f plant that potentially requires to be depressurized after overall shutdown and calculate the amount o f l i q u i d that enters the K O D (Post E S D v o l u m e ) . In case the distance between H H L L and E H H L L is less than lOOmm, 100 m m shall be used.

Figure 3 depicts a revised version o f A P I representation o f flare K O D s h o w i n g both Dead and Post E S D volumes.



/«,

Please visit w w w . l i n k e d i n . c o m / i i r o u p s / C h c m w o r k - 3 8 2 2 4 5 0 should you have any comment, question or or feel free to S. Rah i m i(tV) gma i 1.com.

- -'Si.

6