Design of Compressor Suction Scrubbers_Noijen_Clinton

Design of Compressor Suction Scrubbers Or “Don’t wreck the expensive compressor with cheap scrubbers or with inadequate engineering ” TEKNA-Conference Norway, 26-27 September 2012

Hans Nooijen, GSNL-PTD/TRD

Paul Clinton, GSNL-PTU/EKUW

Principal Technologist Distillation

Principal Concept Engineer

Copyright of Shell Global Solutions International B.V.

DEFINITIONS AND CAUTIONARY NOTE Resources: Our use of the term “resources” in this announcement announcement includes quantities of oil and gas not yet classified as Securities and Exchange Commission of the United States ("SEC") proved oil and gas reserves or SEC proven mining reserves. Resources are consistent with the Society of Petroleum Engineers 2P and 2C definitions.

The companies in which Royal Dutch Shell plc directly and indirectly owns investments are separate entities. In this announcement "Shell", "Shell Group" and "Royal Dutch Shell" are sometimes used for convenience where references are made to Royal Dutch Shell plc and its subsidiaries in general. Likewise, the words "we", "us" and "our" are also used to refer to subsidiaries in general or to those who work for them. These expressions are also used where no useful purpose is served by identifying the particular company or companies. "Subsidiaries", "Shell subsidiaries" and "Shell companies" as used in this announcement refe r to companies in which Shell either directly or indirectly has control, by having either a majority of the voting rights or the right to exercise a controlling influence. The companies in which Shell has significant influence but not control are referred to as "associated companies" or "associates" and companies in which Shell has joint control are referred to as "jointly controlled entities". In this announcement, associates and jointly controlled entities are also referred to as "equity-accounted investments". The term "Shell interest" is used for convenience to indicate the direct and/or indirect (for example, through our 23 per cent. shareholding in Woodside Petroleum Ltd.) ownership interest held by Shell in a venture, partnership or company, after exclusion of all third-party interest.

This announcement contains forward looking statements concerning the financial condition, results of operations and businesses of Shell and the Shell Group. All statements other than statements of historical fact are, or may be deemed to be, forward-looking statements. Forward-looking statements are statements of future expectations that are based on management's current expectations and assumptions and involve known and unknown risks and uncertainties that could cause actual results, performance or events to differ materially from those expressed or implied in t hese statements. Forward-looking statements include, among other things, statements concerning the potential exposure of Shell and the Shell Group to market risks and statements expressing management’s expecta expectations, beliefs, estimates, forecasts, projections and assumptions. These forward looking statements are identified by their use of terms and phrases such as "anticipate", "believe", "could", "estimate", "expect", "goals", "intend", "may", "objectives", "outlook", "plan", "probably", "project", "risks", "seek", "should", "target", "will" and similar terms and phrases. There are a number of factors that could affect the future operations of Shell and the Shell Group and could cause those results to diffe r materially from those expressed in the forward looking statements included in this announcement, including (without limitation): (a) price fluctuations in crude oil and natural gas; (b) changes in demand for Shell's products; (c) currency fluctuations; (d) drilling and production results; (e) reserves estimates; (f) loss of market share and industry competition; (g) environmental and physical risks; (h) risks risks associated with the identification of suitable potential acquisition properties and targets, and successful negotiation and completion of such transactions; (i) the risk of doing business in developing countries and countries subject to international sanctions; (j) legislative, fisca l and regulatory developments including regulatory measures addressing climate change; (k) economic and financial market conditions in various countries and regions; (l) political risks, including the risks of expropriation and renegotiation of the terms of contracts with governmental entities, delays or advancements in the approval of projects and delays in the reimbursement for shared costs; and (m) changes in trading conditions. All forward looking statements contained in this announcement are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Readers should not place undue reliance on forward looking statements. Additional factors that may affect future results are contained in Shell's 20-F for the year ended 31 December 2011 (available at www.shell.com/investor www.shell.com/investor and www.sec.gov ). These factors also should be considered by the reader. Each forward looking statement speaks speaks only as of the date of this announcement,22 announcement,22 February 2012. 2012. Neither Shell nor any of its subsidiaries nor the Shell Group undertake any obligation to publicly update or revise any forward looking statement as a result of new inform ation, future events or other information. In light of these risks, results could differ materially from those stated, implied or inferred from the forward looking statements contained in this announcement.

Shell may have used certain terms, such as resources, in this announcement that the SEC strictly prohibits Shell from including in its filings with the SEC. U.S. investors are urged to consider closely the disclosure in Shell's Form 20-F, File No 1-32575, available on the SEC website www.sec.gov. www.sec.gov. You can also obtain these forms from the SEC by calling 1-800-SEC-0330.


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DEFINITIONS AND CAUTIONARY NOTE Resources: Our use of the term “resources” in this announcement announcement includes quantities of oil and gas not yet classified as Securities and Exchange Commission of the United States ("SEC") proved oil and gas reserves or SEC proven mining reserves. Resources are consistent with the Society of Petroleum Engineers 2P and 2C definitions.

The companies in which Royal Dutch Shell plc directly and indirectly owns investments are separate entities. In this announcement "Shell", "Shell Group" and "Royal Dutch Shell" are sometimes used for convenience where references are made to Royal Dutch Shell plc and its subsidiaries in general. Likewise, the words "we", "us" and "our" are also used to refer to subsidiaries in general or to those who work for them. These expressions are also used where no useful purpose is served by identifying the particular company or companies. "Subsidiaries", "Shell subsidiaries" and "Shell companies" as used in this announcement refe r to companies in which Shell either directly or indirectly has control, by having either a majority of the voting rights or the right to exercise a controlling influence. The companies in which Shell has significant influence but not control are referred to as "associated companies" or "associates" and companies in which Shell has joint control are referred to as "jointly controlled entities". In this announcement, associates and jointly controlled entities are also referred to as "equity-accounted investments". The term "Shell interest" is used for convenience to indicate the direct and/or indirect (for example, through our 23 per cent. shareholding in Woodside Petroleum Ltd.) ownership interest held by Shell in a venture, partnership or company, after exclusion of all third-party interest.

This announcement contains forward looking statements concerning the financial condition, results of operations and businesses of Shell and the Shell Group. All statements other than statements of historical fact are, or may be deemed to be, forward-looking statements. Forward-looking statements are statements of future expectations that are based on management's current expectations and assumptions and involve known and unknown risks and uncertainties that could cause actual results, performance or events to differ materially from those expressed or implied in t hese statements. Forward-looking statements include, among other things, statements concerning the potential exposure of Shell and the Shell Group to market risks and statements expressing management’s expecta expectations, beliefs, estimates, forecasts, projections and assumptions. These forward looking statements are identified by their use of terms and phrases such as "anticipate", "believe", "could", "estimate", "expect", "goals", "intend", "may", "objectives", "outlook", "plan", "probably", "project", "risks", "seek", "should", "target", "will" and similar terms and phrases. There are a number of factors that could affect the future operations of Shell and the Shell Group and could cause those results to diffe r materially from those expressed in the forward looking statements included in this announcement, including (without limitation): (a) price fluctuations in crude oil and natural gas; (b) changes in demand for Shell's products; (c) currency fluctuations; (d) drilling and production results; (e) reserves estimates; (f) loss of market share and industry competition; (g) environmental and physical risks; (h) risks risks associated with the identification of suitable potential acquisition properties and targets, and successful negotiation and completion of such transactions; (i) the risk of doing business in developing countries and countries subject to international sanctions; (j) legislative, fisca l and regulatory developments including regulatory measures addressing climate change; (k) economic and financial market conditions in various countries and regions; (l) political risks, including the risks of expropriation and renegotiation of the terms of contracts with governmental entities, delays or advancements in the approval of projects and delays in the reimbursement for shared costs; and (m) changes in trading conditions. All forward looking statements contained in this announcement are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Readers should not place undue reliance on forward looking statements. Additional factors that may affect future results are contained in Shell's 20-F for the year ended 31 December 2011 (available at www.shell.com/investor www.shell.com/investor and www.sec.gov ). These factors also should be considered by the reader. Each forward looking statement speaks speaks only as of the date of this announcement,22 announcement,22 February 2012. 2012. Neither Shell nor any of its subsidiaries nor the Shell Group undertake any obligation to publicly update or revise any forward looking statement as a result of new inform ation, future events or other information. In light of these risks, results could differ materially from those stated, implied or inferred from the forward looking statements contained in this announcement.

Shell may have used certain terms, such as resources, in this announcement that the SEC strictly prohibits Shell from including in its filings with the SEC. U.S. investors are urged to consider closely the disclosure in Shell's Form 20-F, File No 1-32575, available on the SEC website www.sec.gov. www.sec.gov. You can also obtain these forms from the SEC by calling 1-800-SEC-0330.


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CONTENTS

1. What is the problem? 2. It’s an old problem and it’s an ongoing problem 3. Why do we get it wrong? 4. Examples of getting it wrong. 5. How should we get it right?


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1 WHAT’S WHA T’S THE T HE PROBLEM? PROBL EM?


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WHAT IS THE PROBLEM?

Inadequate separation upstream of compressors results in: 

Liquids entering the compressor



Dissolved and entrained solids entering the compressor

Effect on the compressor: 

Erosion



Deposition of solids

Eventual consequences: 

Reduction of compression efficiency = loss of performance



Rotor imbalance - more unscheduled maintenance



Possible catastrophic failure


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2

IT’S:

An old problem A current problem An ongoing problem


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COMPRESSOR FOULING - IT’S AN OLD PROBLEM

27 May 1984

Case 1 Lift Gas Compressors Performance Check K-614

The second stage discharge pressure is higher than expected. The high pressure trip has been reached and the machine keeps tripping. The problem has been getting worse and it is suspected that carry-over is fouling the machine up. This would have its greatest effect in the third stage where the clearances are smaller.


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CASE 1 IN 2006

The liquid being drained from the casing drain resembled heavy crude rather than condensate.

GS.06.50099 Case 1 Visit Report : COMPRI & Smart Fields Scouting Study Copyright of Shell Global Solutions International B.V.

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CASE 2


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CASE 3

Salt deposits


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CASE 4 - FOULED DIFFUSER


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CASE 5 - 1ST STAGE COMPRESSOR INLET EYE


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CASE 6 COMPRESSOR - EROSION


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CASE 7 CATASTROPHIC FAILURE

When machine was opened, these pools of liquid were found in it.


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CASE 7 - PIECE BROKEN OFF IMPELLER


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CASE 7 - BROKEN SEAL


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3 WHY DO WE GET IT WRONG?


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WHY DO WE GET IT WRONG?



Ignorance - not thinking about our design and not understanding what is happening in our own process



Not following established good practice



Delegating design responsibility



Lack of attention to detail



No close supervision of contractors



Package unit & vendor guarantee mentality



Concept of “Industry standard”



Attempt to save money


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HOW DOES A COMPRESSOR SUCTION SCRUBBER WORK? Vessel 







Provides larger flow area to reduce flow velocity For gas dominated two phase flow, vertical vessel makes best use of available area If high proportion of liquid, need pre-separation Control volume for separated liquid

Outlet nozzle & pipe 

Avoids channeling of flow in the demister

Demisting internals  





Remove liquids by various means Merge small droplets into bigger droplets Catch the droplets (cyclones, flow direction change, etc Return removed liquid to bottom of vessel

Inlet device Inlet nozzle & pipe Avoids severe maldistribution of two phase flow across pipe area  Provides non slugging flow regime  If mist flow be careful - if very small droplet size,International difficultB.V. to Copyright of Shell Global Solutions 

Makes coarse gas/liquid separation  Distributes gas flow across vessel area  Avoids re-entrainment of droplets 

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UNDERSTANDING BEGINS AT THE PFS What is wrong with thisare PFS? Production separators only (what is missing?) bulk separators, just like slug catchers.

Suction scrubber was missing

wells Flowlines manifold (5 - 10 km long) Copyright of Shell Global Solutions International B.V.

Production separator

A clue: Now the second stage is shown

compressor

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UNDERSTANDING CONTINUES TO PEFS WhatInstructions instruction to is avoid missing slug from formation! these PEFSs?

Slope, do not pocket Slope, do not pocket To compressor

Slope, do not pocket From separator

To second compression train, see PEFS xyz

PEFS Production separator Copyright of Shell Global Solutions International B.V.

PEFS Compression 10/2/2012

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RUNNING PIPING TO COMPRESSORS - PLAN VIEW

Distance can be > 100 m

Compression train

Well flowlines Piping dept don’t know about slugs and the capabilities of your separators. If you don’t instruct otherwise they will run the pipes in the most convenient way:  At grade  Underground Copyright of Shell Global Solutions International B.V.

Compression train 10/2/2012

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RUNNING PIPING TO COMPRESSORS - ELEVATION VIEW Suction scrubbers are not slugcatchers. When a slug hits the suction scrubber, a significant proportion will leave in the gas and enter the compressor.

Production separator

This gas pipe is now similar to a two phase cross country pipeline. And it also has slugs:  Terrain induced  Flow rate induced A half full 100m long 30 inch pipe holds 7 m3 ofCopyright liquid! of Shell Global Solutions International B.V.

r n e o b i t b c u u r S c s

Worst case is starting another compressor. The equilibrium hold up changes and a huge slug can be generated.  High carryover to compressor  LZHH may be reached on running machines - which will trip.10/2/2012

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I CAN SOLVE THAT WITH A DRAIN POT!

LZHH

By the time you have engineered the drain pot, how high must the pipe be elevated? Definitely higher than it used to be!

Range for control LZLL

Clearance for access


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IF YOU CANNOT ELIMINATE SLUGS, ONLY PROPER SOLUTION IS A SLUGCATCHER To suction scrubber

Long pipe

slugcatcher

The slugcatcher will eliminate slugs. Liquid removal by dip tube or occasional blowdown are desperate measures for constructed plant. They should not be engineered into a new design. Copyright of Shell Global Solutions International B.V.

Underground slugcatchers are nice for the hydraulics, but very difficult for maintenance and safety. (don’t do it) Don’t forget that the compressor will still require a suction scrubber. 10/2/2012

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SUCTION SCRUBBER INLET & OUTLET PIPING

Inlet nozzle straight length requirement. Slope, do not pocket

Outlet nozzle v2 requirement usually needs larger pipe size. Note 2 Outlet nozzle straight length requirement.

Note 1

Inlet nozzle v2 requirement usually needs larger pipe size. Note 1. No bends in horizontal plane, valves or swages allowed within 10 pipe diameters of inlet nozzle Note 2. No bends in horizontal plane, valves or swages allowed within 2 pipe diameters of outlet nozzle Copyright of Shell Global Solutions International B.V.

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DEVIATION FROM SEPARATOR DEP Vendor Special     

Exciting new technology Smaller vessel Cheaper! CFD based design Great list of installed units (but have you spoken to them?)

DEP Separator  

Established technology Based on many actual field tests across Shell Group

Deviation Control  

Not applying the DEP requires approval to deviate from Shell pract ice. You are not authorized to make this decision.

Why Gamble? 

Taking a gamble on a cheaper scrubber is just not worth the risk of compressor damage. Copyright of Shell Global Solutions International B.V.

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4 EXAMPLES OF GETTING IT WRONG Please remember that all these examples were engineered by engineers - it wasn’t an accident.


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CASE 1 IN 2006

The root cause failure report for K 0611 highlighted (utilizing thermo-graphic photos) that the liquid suction header for the inlet scrubber was half filled with liquids (low section of the header). This is the suction header to inlet scrubber V-0610. Copyright of Shell Global Solutions International B.V.

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CASE 8

Long underground lines from flow station Copyright of Shell Global Solutions International B.V.

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CASE 1 K-614 SCRUBBER - VESSEL DATA SHEET

What basis is there for believing that this proprietary separator will work?


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CASE 1 K-614 SCRUBBER - IT GETS EVEN WORSE

Dresser stated that they were unable to comply with 24” manway requirements. Customer (x) agreed for vessels with no internals.


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PROPRIETARY SEPARATOR – CASE 9

Outlet 12” Flow evenly distributed across vane pack?

Channelling through vane pack?

Vessel ID = 750 mm

Re-entrainment of droplets?

Inlet 12” Copyright of Shell Global Solutions International B.V.

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CASE 9 PROPRIETARY SEPARATOR - EVALUATION In September 2003 severe rotor damage of the Export compressor K -83502 occurred. Liquid carryover from the suction scrubber vessel V-83502 was identified as a possible cause of failure. To quantify the level of liquid carryover and to determine the separation efficiency of the scrubber V-83502, a dedicated isokinetic sampling campaign was carried out by Shell Global Solution (SGSi-OGRD) over the period 10 to 12 October 2004. The vendor guarantee specification for liquid in the off gas from this scrubber is < 13 litres/MMsm3 (0.1 US gal/MMsft3). This translates to an actual liquid concentration of < 10 ppmw in the scrubber off gas. Conclusions The measurements from the isokinetic sampling showed an average liquid –in –gas concentration of 0.19wt% with a

separator liquid removal efficiency of 68%.

The vendor guarantee separator performance of 0.1 Usgal/MMsft3 (or 13 liters/MMsm3) carryover in the gas, which equates to a separation efficiency of 99.8%, is by far not being achieved . Copyright of Shell Global Solutions International B.V. Ref OG.04.50720

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CASE 10 - INCORRECT INLET PIPING TO SUCTION SCRUBBER Case 10 Pre-start-up audit, July 2005

Bend in horizontal plane violating 10D straight length requirement.


V-1410 Propane compressor suction scrubber

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5 HOW SHOULD WE GET IT RIGHT?


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HOW SHOULD WE GET IT RIGHT?



Understand the problem and how to avoid it.



Follow established good practice:





Use the Separator DEP



Eliminate slugs and keep them from re-forming



Pipework configuration correct

Don’t delegate design responsibility: 



Put “high level” philosophical requirements in BOD & BDP

Ensure that our requirements are fulfilled: 

Project spec contractor to correctly express our philosophical

requirements in the EPC bid document 

EPC contractor to purchase accordingly



EPC contractor to construct accordingly


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RELATIONSHIPS & EXPERTISE





There is no reason for the expertise not to be at the Principal’s end. That expertise should be you!

relationship Principal (asset owner) p i h s n o i t a l e r

Technical advisor

relationship Design contractor

relationship

Vendor

Fabricator

Who is making the decisions? Who is truly providing the guarantee? Where is the expertise? Who really knows how the equipment will perform?

Is the process engineering expertise in the project at the Principal’s end or the other end?


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THANK YOU FOR YOUR ATTENTION


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SURGE FACTORS For the production separator upstream of the compressor suction scrubber DEP 31.22.05.11-Gen. September 2002 In E&P Offshore service

Separator handling natural-flowing production from: a) its own platform b) another platform or well jacket in shallow water c) another platform or well in deep water Separator handling gas lifted production from: a) its own platform b) another platform or well jacket In E&P Onshore service Separator handling natural flowing production, or gas plant inlet separator in: a) flat or low rolling country b) hilly country Separator handling gas lifted production in: a) flat or low rolling country b) hilly country In Refineries and Chemical plants: The design margin ranges typically from Copyright of Shell Global Solutions International B.V.

1.2 1.3 1.4 1.4 1.5

1.2 1.3 1.4 1.5 1.15 to 1.25 10/2/2012

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CORROSION EROSION


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THRUST BEARING (BOTTOM) & SEAL


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RECIPROCATING COMPRESSOR OUTBOARD DISCHARGE VALVE


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Design of Compressor Suction Scrubbers_Noijen_Clinton

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