By: Bader Ba-Hammam Problem Statement TT here is high sulfur in Propane (C3) & Butane (C4) products coming from JGP to the customers in Jubail such

By: Bader Ba-Hammam

Problem StatementProblem Statement

There is high sulfur in Propane (C3) & Butane (C4) products coming from JGP to the customers in Jubail such as Ibn Sina & Sadaf.

Generally, JGP practice to maintain sulfur below 20ppm or well below the 30ppm specification, to allow for possible process upset or errors in reading or measurements that could produce off-spec products

JGP management takes the responsibility and the commitment to reduce sulfur to be on specification and gain customer satisfaction.

A team was assembled to review the problem with the objective of determining if the modification can be made to increase the reliability and operation performance of the MEROX unit.

Study MethodologyStudy Methodology

Define the problem.

Identify and evaluate possible causes.

Find solutions and identify recommendations.

Implement the changes.

Define The ProblemDefine The Problem

Identify the big problem Using the “Three Actual” rule to understand the problem before

solving it by collecting data from the right sources

• Go to actual place

• See the actual process

• Talk to the people (operation & maintenance)


Describe the process JGP has 3 existing fractionation modules and a new module in

construction phase.

In each module, there is a MEROX Unit that reduce the Sulfur

concentration on the products.

Fractionation Unit Overview

MEROX Introduction

Measure the process performance

Fractionation Unit OverviewFractionation Unit Overview

MEROX: Mercaptan Oxidation.

MEROX unit reduces LPG sulfur content to meet customers product specifications.

MEROX IntroductionMEROX Introduction

What does MEROX process consist of?

MEROX IntroductionMEROX Introduction

Mercaptan Sulfur Extraction SectionUtilization of caustic solution to extract mercaptans sulfur from LPG products as they are converted to mercaptides.

Caustic Regeneration SectionUtilization of catalyst and air to regenerate caustic solution as the mercaptides are converted furthermore to insoluble disulfides.

Prewash Drum

Extractor

Regenerated Caustic

Contaminated Caustic

Treated Product

San

d F

ilter

Caustic Settler

LPG

SulfurSulfur Extraction Extraction

Blockage of Merox unit equipment due to salt formation

Mr. LPGH2S


Extractor

San

d F

ilter

Caustic Settler


Prewash Drum

NaOH(Caustic)


H2S + 2NaOH Na2S + 2H2O

Extractor

San

d F

ilter

Caustic Settler

Prewash Drum


Off specification LPG products

RSH(Mercaptans)


NaOH

San

d F

ilter

Caustic Settler

Prewash Drum

Extractor


Legend

Mercaptans

NaOH Solution

Hydrocarbon


RSH + NaOH NaSR + H2O

NaSR(Mercaptide)


RSH(Mercaptans)

San

d F

ilter

Caustic Settler

Prewash Drum


Extractor

Prewash Drum

San

d F

ilter



Treated Product

Caustic Settler

Extractor

O

X

I

D

I

Z

E

R

Process AirContaminated Air


Disulfide Oil

CausticHeater

Regenerated Caustic

To atmosphere

60 PSIG Steam

To Crude

Caustic RegenerationCaustic Regeneration

Disulfide Separator

VentTank

Catalyst Add. Pot

O

X

I

D

I

Z

E

R

Process

Air

CausticHeater

O

X

I

D

I

Z

E

R

Disulfide Separator

VentTank


CatalystO2

NaSR+ + ½ H2O ½ RSSR + NaOH

RSSR(Disulfides)


NaSR(Mercaptides)

Merox Catalyst

41

Depleted Air

O

X

I

D

I

Z

E

RCausticHeater

RegenerationRegeneration

Disulfide Separator

VentTank

Regenerated Caustic

To Crude

San

d F

ilter

Prewash Drum

Treated Product



Extractor Caustic Settler

Process

AirDepleted

Air

O

X

I

D

I

Z

E

R

RegenerationRegeneration

Disulfide Separator

VentTank

Regenerated Caustic

To CrudeCausticHeater


Measure the process performance• The two figures show product sulfur as determined by laboratory analysis in C3 and C4 products,

respectively, between February 2005 and February 2006.

• During this period, as can be seen from the figures, there has been total of only 2 periods where off-spec product (>30ppm) was actually produced from one of the three Modules; Mod II in February 05 and Mod I in early November 05. During these incidences, the other modules were producing on-spec product.

• Note that the off-spec readings obtained in January 05 for C4 and C3 are accounted for by problems at RT lab.

• In addition, there were 16 days in which C3 product sulfur exceeded 20ppm but were still on-spec.

• Also, there have been a total of 46 incidences where C4 product sulfur ranges between 20ppm and 30ppm. (32 periods between 20-25ppm & 14 periods between 25-30ppm)

• To have off-spec C3 while having on-spec C4 would mean that the process is not functioning properly.





Identify & Evaluate Possible Causes Identify & Evaluate Possible Causes

JGP formed a team consisting of 2 process engineers, 1 instrument engineer,

1 maintenance engineer, 2 area operation foremen and 1 maintenance

foreman.

Brainstorming session was conducted to list all the possible root causes that

could lead to high sulfur in the C3/C4 products.

The team was able to identify approximately 20 conditions or causes that

could either lead to off-spec product or give the perception that off-spec

product was being produced.

Cause and Effect diagram was identified as follow:

High Sulfur in C3/C4 Products

Operation/ People procedure

RT Lab Equipment

Sulfur not removed by MEROX

Valve Plugging problem

High MEROX Catalyst Strength

Low Caustic Strength

Low MEROX Cat Strength

Wrong O2 Analyzer

Low Temp Inlet

to OxidizerLow O2 Flow

Analyzer

High Quantity of Inlet Sulfur

Low HC Flow

Carryover

High HC Feed Rates

Low Caustic Flow

Level Control

Extractor Level Tx

Faulty Lab Results

C4 From RT

Re Entry Sulfur

On-line Analyzer

Interface Level Control

IdentifyIdentify & Evaluate Possible Causes& Evaluate Possible Causes

Identify & Evaluate Possible Causes Identify & Evaluate Possible Causes

After listing all the causes, the team outlined tools available for plant

personnel to detect the conditions and outlined the actions that should be

taken.

Moreover, the frequency of the event occurring and a severity index were

assigned to each cause. this severity index is meant to be an estimate of the

amount of time before the condition, if left unnoticed or if no action was

taken to eliminate the cause, may lead to off-spec product.

In addition, safeguards were identified to list all the tools in place to alert

personnel that such conditions or causes were occurring.


Causes How to Detect What Actions Frequency Severity Safeguards

High quantity of inlet sulfur

AnalyzersChange caustic

turndown feed (call OSPAS)

Low 5 Analyzer Alarm

Sulfur not removed by MEROX

AnalyzersIncrease reflux on

DeC4Low 4 Analyzer Alarm

High HC feed rates Flow meters Lower capacityC3 - medium

C4 - high2 Surge drum alarm

Low HC flow Flow meters recycle to reflux

drumLow 3 FCV alarm

Low caustic flow FCV, level extractor Increase flow Low 4 Level alarm

Level in Extractortransmitter, level

switchcheck LCV, add

causticMedium 1

level transmitter alarm

CarryoverLevel in the settler boot, high sulfur

reduce rate Low 1Feed Management

Program

Low Temp inlet to Oxidizer

Low ΔT, high O2increase heater

TempLow 3

Analyzer Alarm, Temp Alarm

Low MEROX Catalyst Strength

Shake Test, 3x/day Add MEROX Medium 3 ----

High MEROX Catalyst Strength

Emulsion in caustic shelter

Dump caustic Low 2 Shake test


Low O2 flow to Oxidizer

O2 analyzer, Air flow meter

check analyzer using 3in1 portable

analyzerMedium 4 O2 analyzer alarm

Wrong O2 analysisO2 analyzer, Air flow

meter

check analyzer using 3in1 portable

analyzerHigh 4

3in1 portable analyzer

Low caustic strength Lab resultsMake-up with HS

causticLow 3 ----

Re-Entry SulfurLevel in DS drum,

analyzer, labLow O2 rate, Low

MEROXMedium 5 ----

Level control LT-651

High level in Ext, off spec product, re-entry sulfur

Maintain LT Low 3Verify low flow alarm

to Ext

Interface Level Control LT-650

---- Maintain LT High 5 ----

DS Oil Plugging problems

---- Maintain Valve High 5 ----

C4 from RTAnalyzers, Lab 2x-

3x/week, customers

Call RT, Stop receiving from

RTLow 5 ----

Faulty Lab Results Take check samplecheck sample, check

processLow 2 ----

On-Line Analyzer ---- ---- ---- ---- ----

Find Solutions & Identify RecommendationsFind Solutions & Identify Recommendations

Brainstorming session was conducted to list all the possible solutions

and proposed recommendations.

Although the unavailability of reliable analysis of the product from RT

lab is one of the primary cause of the problem, this specific issue is not

addressed because the laboratory has already taken steps to correct

matters.

As a result, the team has identified 17 recommendations to overcome

the problems currently being experienced in the MEROX unit.


The affinity diagram was conducted to sub-divide the recommendations into sections as

per following:

Section 1) Most Important; reduce the possibility of high sulfur products by providing

operation/engineering with timely and needed information about the unit.

1) On-line GC

2) Create poster to hang outside showing procedure for shake test

3) Log results of shake test in DCS

4) Create MEROX dashboard: DCS/PI schematic to show overview of important parameter for

MEROX performance as per decision tree in JIM 1504.33-1

5) Evaluate available and proven disulfide-caustic interface detection instrument

6) EJR to install water flush line to remove plugs from LCV-650


Section 2) General Items; to provide the operator with better information when sulfur

begins to rise as well as reemphasizing instruments PMs.

7) Consider increasing O2 alarm to 10%

8) Add ΔT reading & alarm in DCS for all oxidizers

9) Make On-line GC schematic in PI containing all sulfur information

10) Install seal pot on O2 analyzer

11) Replace F&PS analyzer installed to measure sulfur in RT C4 because it is not

reliable due to manufacturer's defect

12) Monthly PM for level & interface instruments


Section 3) Long-Term; for evaluation & studies.

13) Check Mod III inlet analyzer for accuracy

14) Evaluate “rate of change” alarm for level in Extractor

15) Evaluate installing flow transmitter on Disulfide oil flow

16) Evaluate enlarging DS oil line from 1 to 2

17) Consider adding balance calculation to alert operations when TR C4

combined with JGP C4 approached off-spec.

Implement The ChangesImplement The Changes

Each proposed recommendation was assigned to the right employee depending on his

specialty to ensure the fulfillment of the recommendation by eliminating the cause of high

sulfur product and following-up by evaluating and measuring the performance after the

change.

My role was to evaluate the existing interface level transmitter for all the Modules and then

search and evaluate new technologies.

It is found that the displacement type installed in JGP Mods is not suitable to detect interface

level and it is not recommended by ARAMCO consultants.

There are many interface level detectors methods used around the world for different

applications. These instruments should be studied very carefully from all aspects to have the

right one for JGP application.

NaOHMerox CatalystH2S

Mr. LPG

Documents

By: Bader Ba-Hammam Problem Statement TT here is high sulfur in Propane (C3) & Butane (C4) products coming from JGP to the customers in Jubail such