BORL HCU-DHT APC Scoping Study Report (Final)

7/23/2019 BORL HCU-DHT APC Scoping Study Report (Final)

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A Report on the Scoping Study for Advance

Process Control Implementation in HCU &DHT Units

at

BHARAT OMAN REFINERIES

LIMITED, BINA, MADHYA

PRADESH, INDIA

Submitted By

YOKOGAWA INDIA LIMITED,

BANGALORE

December 2013



Customer: Bharat Oman Refineries Limited

Project: Scoping Study for APC Implementation in HGU & HCU-DHT Units

Yokogawa India Limited, Bangalore Confidential

Doc. No: BORL-AB1-001

Revision History

Revision Date Prepared Checked Approved 0.0 15 Dec 13 Anjan K Datta Anjan K Datta Anil Dutt

Seyed Masood ARohit Ravichandran

1.0 30 Dec 13 Anjan K Datta Anjan K Datta Anil DuttSeyed Masood ARohit Ravichandran

2.0 15 Apr 14 Anjan K Datta Anjan K Datta Anil Dutt

Seyed Masood ARohit Ravichandran

3.0 12 May 14 Anjan K Datta Anjan K Datta Anil DuttSeyed Masood A







Contents

1.0 INTRODUCTION & ACKNOWLEDGEMENT ................................................. 1

2.0 EXECUTIVE SUMMARY ..................................................................................... 3

3.0 REVIEW OF PLANT OPERATION & CONTROL OF HCR-DHT UNIT...... 6

3.1 HCR 1ST STAGE................................................................................................................... 6

3.2 HCR 2 ND STAGE .................................................................................................................. 7

3.3 DHT ................................................................................................................................... 8

3.4 LIQUID PRODUCTS .............................................................................................................. 8

3.5 LIGHT E ND R ECOVERY (LER) SECTION............................................................................. 9

3.6 GAS R ECOVERY SECTION ................................................................................................... 9

4.0 PROPOSED APC STRATEGIES AND HARDWARE CONSTRAINTS OF

HCR-DHT UNIT ................................................................................................................ 10

4.1 R EACTOR CONTROL ............................................................................................................... 10

4.2 STRIPPER & FRACTIONATOR CONTROL ................................................................................. 11

4.3 DEETHANIZER & SPONGE ABSORBER CONTROL .................................................................. 12

4.4 DEBUTANIZER CONTROL ...................................................................................................... 12

4.5 NAPHTHA SPLITTER CONTROL.............................................................................................. 12

4.6 HCR & DHT FRACTIONATOR FURNACE CONTROL .............................................................. 12

4.7 HARDWARE / INSTRUMENT / PROCESS ISSUES OR CONSTRAINTS ....................... 13

5.0 QUANTIFICATION OF EXPECTED ECONOMIC BENEFIT ............................ 14

5.1 BENEFIT ESTIMATION METHOD ............................................................................................. 14

5.2 BASIS FOR BENEFIT ESTIMATION .......................................................................................... 16

5.3 QUANTIFICATION OF BENEFITS FOR HCR-DHT SECTION ..................................................... 18

5.3.1 MAXIMIZATION OF LPG ..................................................................................................... 18

5.3.2 MAXIMIZATION OF HCR DIESEL ....................................................................................... 19

5.3.3 MAXIMIZATION OF DHT DIESEL ....................................................................................... 21

5.3.4 MAXIMIZATION OF HEAT R ECOVERY IN F/E EXCHANGERS .............................................. 22

5.3.5 MAXIMIZATION OF STEAM GENERATION IN HEAVY DIESEL PUMP-AROUND CIRCUIT ...... 23







5.3.6 EXCESS AIR MINIMIZATION IN HCR FRACTIONATOR HEATER & DHT R EBOILER

FURNACES (WITHIN ALLOWABLE R ANGE) ................................................................................... 23

5.3.7 CONTROL & OPTIMIZATION OF GAS-TO-OIL R ATIO IN HCR 1ST STAGE (WITHIN

ALLOWABLE R ANGE) .................................................................................................................... 24

5.4 TOTAL EXPECTED APC BENEFIT ........................................................................................... 26

5.4.1 TOTAL EXPECTED APC BENEFIT IN HCR-DHT SECTION .................................................. 26

6.0 INSTRUMENTATION & HARDWARE REQUIREMENT FOR DCS

CONNECTIVITY WITH APC ........................................................................................ 28

6.1 RECOMMENDED SYSTEM ARCHITECTURE FOR APC SYSTEM ............... 30

7.0 TECHNICAL SPECIFICATIONS ............................................................................ 31

HARDWARE REQUIREMENTS (PER U NIT) ............................................................................. 31

(A) HARDWARE R EQUIREMENTS FOR HCR-DHT: ........................................................................ 31

(B) ADDITIONAL COMMON HARDWARE R EQUIREMENTS FOR HGU AND HCR-DHT** .............. 31

SOFTWARE REQUIREMENTS (PER U NIT) ............................................................................... 33

8.0 PROJECT EXECUTION & SCHEDULE ................................................................ 34

8.1 K ICK -OFF MEETING (KOM) ............................................................................................ 34

8.2 PROCESS STUDY ............................................................................................................... 34

8.3 PRETEST ........................................................................................................................... 34

8.4 STEPTEST.......................................................................................................................... 35

8.5 E NGINEERING ................................................................................................................... 35

8.6 COMMISSIONING .............................................................................................................. 36

8.7 SITE ACTIVITY TEST (SAT) ............................................................................................. 36

8.8 POST-AUDIT ..................................................................................................................... 36

9.0 TRAINING REQUIREMENT ............................................................................. 38

10.0 APPROXIMATE COST ESTIMATION ............................................................ 39



Yokogawa India Limited, Bangalore Confidential Page 1


1.0 Introduction & Acknowledgement

The petroleum refinery of Bharat Oman Refineries Limited (BORL) is located at

the village of Agasode, Bina, in the district of Sagar of Madhya Pradesh. The

refinery was designed to process 6 Million Metric Ton of Arab Mix Crude. The

refinery has adopted the state-of-the-art technologies and has the flexibility to

process other types of Crude. The processing units in the refinery include

Atmospheric Crude Distillation & Vacuum Distillation unit (CDU/VDU), and many

downstream units such as Hydrocracker, Hydrogen Generation, Naphtha & Diesel

Hydrotreating, LPG Treating, Fuel Gas Treating, Delayed Coker, CCR,

Isomerization, Sulphur Recovery, Amine Regeneration and Sour Water Stripper.

The Refinery came on-stream in June 2010 and was fully commissioned by May

2011.

BORL want to implement Advanced Process Control (APC) solutions in order to

improve the stability, performance and economic return of the process operations.

Application of APC will not only provide higher economic benefits but also result

in a smoother plant operation. As a first step, BORL has initiated a Scoping Studyfor APC implementation in the HCU, DHT & HGU units, which are important units

in the refinery. Yokogawa India Limited (YIL) has been offered the opportunity to

conduct such a study. YIL has been associated with BORL since its initial project

phase having supplied the Distributed Control System (DCS) and other

instrumentation products to automate the complex processes in this refinery. YIL

Solution team has also provided the PID tuning service to stabilize the DCS control

of various units during the commissioning phase.

The Scoping Study was carried out with the objective of finding various benefits

that can be derived by application of APC technology, hardware and software

requirement for APC implementation, and additional instrumentation and hardware

requirement in order to get the projected benefits from APC. In this connection,

YIL engineers visited BORL’s Bina Refinery from 15th November to 23rd

November of 2013. BORL presented the description, operational strategies and

control objectives of both the process. Operating manuals, DCS Screenshots, and





PFD/P&ID were provided and opportunity was given to know the present state of

the basic regulatory control system. In addition to the Process and Instrumentation

Review, a detailed analysis of Process and Laboratory data over the period of 1st

June 2013 to 30th October 2013 was conducted to establish a baseline performance

of existing process control system and estimate the performance improvement

benefit that can be expected from APC.

An executive summary of the benefit study is provided in the next section.

Following the executive summary, this document further contains the following

sections:

1. Review of Plant Operation & Control

2. Proposed APC Strategy & Hardware Constraints

3. Quantification of Expected Economic Benefit

4. Instrumentation & Hardware Requirement for DCS Connectivity with APC

5. Recommended System Architecture

6. Technical Specification

7. Project Execution and Schedule

8. Training Requirement

9. Approximate Cost Estimation

Acknowledgements:

We express our sincere thanks to the excellent support extended by BORL’s

Managers, Engineers and Technicians in providing the inputs required for this

study. Their contribution and commitment has helped us gain the understanding

necessary for preparing this Report within the stipulated period. Special thanks to

the Technical Services Group for arranging the meetings with Process and

Operations groups which has enabled us to understand the process and operating

constraints.





2.0 Executive Summary

YIL is pleased to present the Scoping Study report to BORL describing in detail the

benefits of implementing Advance Process Control in the HCU, DHT units,

including the hardware and software requirements. Through this study, it has been

found that these two units are prime candidates for APC implementation. APC can

not only stabilize the plant operation but also result in an increase in the yields of

valuable products and decrease in the energy costs.

Although the scope of the study initially included only HCU, the HCU & DHT

units at BORL-Bina are highly interlinked. The lighter and Naphtha products from

both units are combined before separation into OFF gas, LPG, Light Naphtha and

Heavy Naphtha in a common Light End Recovery section. Similarly, KERO

products of HCU & DHT are combined, and HCU Diesel is further blended with

part of the common KERO and Heavy Naphtha streams. The light gases from both

units feed single recycle gas compressor and a PSA unit. The compressed recycle

gas and make-up gas header is also connected to both units. If we consider Gas-to-

Oil Ratio control or optimization in HCU, then Gas-to-Oil Ratio in DHT is to be

considered as constraint. Hence, this report presents benefits achievable for HCU &

DHT together.

Many different areas where APC can result in more stable plant operation,

increased yields of valuable products or enhance energy savings were identified. At

the same time, required changes in hardware, addition of instruments or some

existing process problems have also been identified and provided inside this Report.

These are to be attended before APC implementation. A brief highlight of the

present study is as follows:

APC will consistently maintain the RCAT (or Volume Average Bed

Temperature of each reactor) and STGCAT (Volume Average Bed Temperature

of a Stage) in HCR 1st & 2nd Stage reactors. Apart from this, APC will maintain

Maximum Bed Temperature and Delta Bed Temperature of each bed and Outlet

Temperature for all the reactors.





Yields of valuable products such as Liquefied Petroleum Gas (LPG) and Diesel

(both HCR & DHT Diesel) will be increased while yields of Naphtha and

Kerosene will be decreased by APC through adjustments of product cuts and

other operating conditions in the HCR & DHT Strippers & Fractionators,

Deethanizer, Sponge Absorber and Debutanizer columns so that quality

giveaway is minimized. In order to realize these product yield benefits,

daily-basis Density & ASTM distillation data of Diesel & KERO and Flash

Point data of KERO at the HCR & DHT Fractionator product ends (before

any mixing) will be needed (in addition to the existing data of final

products). Furthermore, the VFD AC fans at the top of HCR & DHT

Strippers and DHT Fractionator are to be made available for manipulation

by APC, and flow meters (preferably with Flow Control Valves) are to be

provided in HN & KERO line to HCR Blend.

APC will manipulate the heavy Diesel Pump-Around circuit return temperature

in order to maximize MP steam generation that happens in the same Pump-Around circuit.

APC will manipulate the FD fan inlet damper opening and cold air dampers to

HCR Fractionator Heater and DHT Reboiler Furnaces in order to minimize

Excess Air within allowable ranges.

APC will maintain HCR 1st & 2nd Stage HCR Reactor s’ Furnace Heater

temperature difference while trying to increase in the heat recovery in the

Feed/Effluent exchangers. However, F/E Heat Recovery will be considered

unrealizable unless the ranges of Furnace temperature differences under

APC control are set around the average values under DCS control.





For the HCU & DHT units, the minimum expected total APC benefit at the

average total throughput of 475 MT/hr or 538 m3/hr is estimated as:

o 2.49 Crore Rs/Yr or 1.53 Cent/Barrel (When F/E Heat Recovery is not

realized)

o 2.78 Crore Rs/Yr or 1.71 Cent/Barrel (When F/E Heat Recovery is

realized)

The tangible APC benefit would be much more since the increases in the LPG yield

by pulling from Light Naphtha could not be added to the above benefit figure.

Similarly, increase of HCR & DHT Diesel by pulling from Kerosene cannot be

added to the above benefit figure.





3.0 Review of Plant Operation & Control of HCR-DHT Unit

The HCR-DHT unit consists of the following process steps:

HCR 1st Stage Feed Section

HCR 1st Stage Furnace & Reactors

HCR 1st Stage Product Flash Vessels

HCR Stripper & Fractionator

HCR 2nd Stage Feed System

HCR 2nd Stage Furnace & Reactors

HCR 2nd Stage Product Flash Vessels

DHT Feed System

DHT Reactor

DHT Product Flash Vessels

DHT Stripper

DHT Fractionator with Furnace Reboiler

Deethanizer & Sponge Oil Absorber Columns

Debutanizer & Naphtha Splitter Columns

Common Product Flash Vessels for Separating Recycle Gas

Recycle Gas Compressor (RGC) & Make-Up Gas Compressor (MUGC) system

HCR feed is a mixture of the followings:

1) Hot & Cold VGO

2) Hot & Cold HCGO

3) Hot & Cold Coker Naphtha

DHT feed is a mixture of the followings:4) Hot & Cold SR Diesel

5) Hot & Cold LCGO

3.1 HCR 1 st Stage

The feed after preheating in Process Heat Exchangers is sent to 1st stage Feed Surge Drum,

from where it is pumped out and mixed with the 1st stage Feed gas coming from Recycle

Gas Header. The combined feed is heated in the 1st Stage F/E Exchanger (EE105A/B) and





then in a natural convection Furnace (FF101). Then, it passes through three reactors.

Reactor 1 (RB101) has two beds with Quench gas injection in between the beds. Reactors 2

& 3 (RB102 & RB103) has two beds each with Quench gas injections at inlet and in

between the beds. 1st Stage Reactor effluent releases heat subsequently to DHT Feed

(EE107), HCR 1st Stage Feed (EE105), HCR Stripper Bottom (EE108) and an MP steam

Generator (EE109).

Reactor effluent then flashes in HCR 1st Stage HHPS (VV102). Liquid from HCR 1st Stage

HHPS passes through pressure reducing valves and joins with HCR 2nd Stage HHPS liquid.

This is then flashed in HCR HLPS (VV103). Liquid from HCR HLPS and HCR CLPS

goes to HCR Stripper (CC501) that uses MP stripping steam. HCR Stripper bottom is

finally heated in a Furnace (FF501) and fed to the HCR Fractionator (CC502), which

produces Naphtha at top. KERO (Kerosene), LD (Light Diesel) and HD (Heavy Diesel) are

withdrawn as side products through respective side strippers. The Fractionator uses LP

stripping steam at bottom and two pump-around loops (e.g., LD & HD pump-around

loops). HD pump around is used to generate MP steam in EE512.

3.2 HCR 2 nd Stage

HCR Fractionator bottom is fed to the HCR 2nd Stage Feed Surge Drum, from where it is

pumped out and mixed with 2nd Stage Feed Gas coming from Recycle Gas Header. The

combined feed is heated in the 2nd Stage F/E Exchanger and then in a natural convection

Furnace (FF201). Then, it passes through two reactors. Reactor 1 (RB201) has two beds

with Quench gas injection in between the beds. Reactor 2 (RB202) has only one bed with

Quench gas injections at inlet. 1st Stage Reactor effluent releases heat subsequently to HCR

2

nd

Stage Feed (EE201) and HCR Stripper Bottom (EE202A/B).

Reactor effluent then flashes in HCR 2nd Stage HHPS (VV202). Liquid from HCR 2nd

Stage HHPS passes through pressure reducing valves and joins with HCR 1st Stage HHPS

liquid before being flashed in HCR HLPS (VV103).





3.3 DHT

The feed after preheating in Process Heat Exchangers is sent to DHT Feed Surge Drum,

from where it is pumped out and mixed with the DHT Feed gas coming from 2 nd Stage

HHPS (VV202). The combined feed is heated in the DHT F/E Exchanger (EE304A/B) and

then in 1st Stage Reactor Effluent / DHT Feed Exchanger (EE107). Then, it passes through

the single Reactor (RB301) that has three beds with Quench gas injection at inlet and in

between the beds. DHT Reactor effluent releases heat subsequently to DHT Feed

(EE304A/B) and feed gas to 2nd Stage (EE305).

Reactor effluent then flashes in DHT HHPS (VV302). Liquid from DHT HHPS passes

through pressure reducing valves and then flashed in DHT HLPS (VV303). Liquid from

DHT HLPS goes to DHT Stripper (CC701) that uses MP stripping steam. DHT Stripper

bottom is heated by the DHT Fractionator bottom (EE702) and fed to the DHT Fractionator

(CC702), which produces Naphtha at top. KERO (Kerosene) is withdrawn as side products

through a side stripper. Part of the Fractionator bottom is heated in a Furnace (FF701) and

sent back to the Fractionator column. The remaining part of DHT Fractionator bottom is

sent to storage via a LP steam generator (EE704) and cooler.

3.4 L iqui d Products

HCR KERO combines with DHT KERO, the proportion of former being much larger. Only

small amount of the combined KERO is blended to HCR & DHT Diesels, the major

portion being sent to KERO storage.

HCR Heavy Diesel combines with HCR Light Diesel. Small amount of KERO, HN &

UCO are also added to the HCR Diesel to maximize Diesel production with desired

specification. At present, there is no flow control valve in the HN & KERO streams being

blended to HCR Diesel.

DHT Diesel flows out as separate Diesel product after mixing with small amount of KERO.





The major portion of UCO (Unconverted Oil) from HCR Fractionator bottom is sent to 2nd

Stage HCR as feed. After sending small amount of UCO as warm-up oil and for HCR

Diesel blending, the rest is sent to storage.

3.5 L ight End Recovery (LER) Section

Overhead gases and liquids (Unstabilized Naphtha) from HCR & DHT Strippers, Sponge

Oil from Sponge Oil Absorber and Deethanizer top vapor are combined, cooled and fed to

the Deethanizer Reflux Drum. The total reflux from this Drum is the feed to the

Deethanizer column (CC601). The heavy components in the sour gas leaving the Reflux

Drum is absorbed by a cooled Heavy Naphtha slip stream in the Sponge Oil Absorber

(CC602). Rich Sponge Oil is sent to Deethanizer Reflux Drum and lean gas is sent as Off-

gas.

Deethanizer bottom is separated into LPG and Stabilized Naphtha in the Debutanizer

column (CC603). Stabilized Naphtha from Debutanizer and the overhead Naphtha from

HCR & DHT Fractionator columns are separated into Light and Heavy Naphtha products

in the Naphtha Splitter column (CC604).

3.6 Gas Recovery Section

Vapors from HCR 1st Stage HHPS and DHT HHPS go to CHPS (VV401). Vapor from

CHPS goes to RGC (Recycle Gas Compressor) suction through HP Amine Absorber.

Liquid from CHPS is passed through pressure reducing valve and then mixed with vapors

from HCR HLPS (VV103) & DHT HLPS (VV303), and fed to CLPS flash vessel

(VV404). Vapor from CLPS goes to MUGC (Make-Up Gas Compressor) through LP

Amine Absorber & a PSA unit in HGU unit.

All reactor Quench flows are sourced from RGC outlet. RGC outlet joins with make-up

hydrogen from MUGC into a single header. The feed gas or recycle flows to HCR 1 st Stage

& 2nd Stage reactor inlets are taken from this header. Due to variation in H2 consumption in

HCR & DHT reactors, MUGC inlet pressure can vary. The excess H2 pressure at MUGC

inlet is preferably flared through the controller 16PIC9601.





4.0 Proposed APC Strategies and Hardware constraints of HCR-DHT

Unit

4.1 Reactor Control

APC can control Reactors variables like Maximum Bed Temperature and Delta Bed

Temperature of each bed, Outlet Temperature and RCAT (i.e., VABT of each reactor) of

each reactor, and STGCAT (VABT of all reactors in a Stage) of 1st stage & 2nd stage

reactors. For DHT Reactor, maximum bed temperature and Delta Bed Temperature of each

bed as well as Reactor Outlet Temperature can be controlled. Apart from these, an

inferential model for controlling Nitrogen in the Feed to 2nd Stage HCR will be provided.

Since there is no on-line indication of reaction conversions on the outlet of the HCR 1st &2nd Stage and DHT reactors, optimization of the Reactor Temperatures cannot be done by

APC.

The 1st stage GOR will be maintained within the desired range (around the design value)

by APC and will be minimized within this range. During site visit, YIL found that the

recycle gas flow available in the 2nd stage was limited by pressure drop to a value lower

than design. Hence, the 2nd stage GOR cannot be maintained within the desired range

(around the design value) by APC, instead it would be controlled within the achievable

range that might be below the design value. Because of this limitation as well as the

unavailability of any measurement for recycle gas flow to DHT, no benefit based on 2nd

stage GOR minimization has been estimated.

APC can control the Furnace temperature differences for the 1st and 2nd Stage HCR

reactors to maximize process heat recovery. However, F/E Heat Recovery will be

considered unrealizable unless the ranges of Furnace temperature differences under

APC control are set around the average values under DCS control.

Throughput control could also be included as an APC strategy. However, many instruments

and hardware are presently running close to their design limits. For example, YIL found

that HCR 1st stage feed pump and DHT feed pump amperage is reaching values very close

to design FLCs (Full Load Currents). Hence, throughput control with APC could be

included after all the hardware and process constraints related to throughput increment are





confirmed before APC design and all the related hardware / instrumentation issues (such

as, availability of constraint measurements) are resolved by BORL. Once feasibility of

throughput control is established, then throughput setpoints could be set so as to maximize

it without violating any constraint.

4.2 Stri pper & Fractionator Control

APC will try to control temperature profiles in the two Stripper and Fractionator columns

by varying top and bottom conditions. In addition, APC will vary Furnace COT and other

conditions in Fractionators to maintain tray temperatures and column delta pressures. APC

will account for variation of throughput and pressure as disturbance variable and will

implement control of pressure compensated temperatures wherever needed in the Strippersand Fractionator columns to maintain product qualities.

At present Density & ASTM distillation data of only Blended HCR Diesel, final DHT

Diesel and Combined KERO, and Flash Point of Combined KERO are taken. For product

optimizations using product draw rates and side stripper heat inputs in the

Fractionator columns, product Density & ASTM distillation data are needed for

column products like Heavy Naphtha, KERO, Diesel & UCO before any

mixing/blending (apart from the existing data for final products). There is flow meter

in the HN line going to the Diesel Blend, and no Flow Control Valves in the HN &

KERO lines going to the Diesel Blend. These are needed for accurate control of Diesel

blending.

Similarly, The VFD AC fans at the top of HCR & DHT Strippers and DHT

Fractionator have to be manipulated by APC in order to control product qualities and

yields.

Based on the confirmation by BORL that daily lab measurement of Density, Flash Point &

ASTM D95% of KERO at HCR & DHT Fractionator ends (before mixing with any other

streams) will be available during APC project; the same qualities in the Combined KERO

will be controlled. Similarly, based on the confirmation by BORL that daily lab

measurement of Density & ASTM D95% of Diesel & UCO at HCR Fractionator end

(before mixing with any other streams) will be available during APC project and that a





flow meter will be installed in the HN line blend; the same qualities in blended HCR Diesel

will be controlled. Similarly, based on the confirmation by BORL that DAILY lab

measurement of density & ASTM D95% of Diesel at DHT Fractionator end (before mixing

with any other streams) are available; the same qualities in blended DHT Diesel (after

mixing with Combined KERO) will be controlled.

In case of HCR Fractionator, pump around flows and TD (temperature difference) will also

be manipulated to control tray temperatures and product quality. At the same time, APC

will control the steam generation in the Heavy Diesel Pump-Around circuit.

Stripping Steam flows to the bottoms of HCR Stripper & Fractionator and DHT Stripper

could be minimized whenever possible without affecting product qualities. Similar

opportunistic minimization could also be done for DHT Fractionator Reboiler duty, and the

VFD AC fans' loading at the top of HCR & DHT Strippers and DHT Fractionator.

However, because of complex dynamics between product qualities and these variables, it is

not possible to quantify any benefit from such optimizations.

4.3 Deethanizer & Sponge Absorber Control

APC will maintain top & bottom temperatures and reflux ratio in Deethanizer. APC will

control HN flow and off gas yield in the Sponge Absorber.

4.4 Debutanizer Control

APC will control top & bottom temperatures and reflux ratio, hence the LPG yield and

Weathering. LPG Weathering inferential will be built for this purpose. LPG Weathering

will be controlled within the specified range while maximizing LPG yield by pulling lightcomponents from LN.

4.5 Naphtha Splitter Control

APC will control top & bottom temperatures and reflux ratio, hence the desired Light and

Heavy Naphtha quality.

4.6 HCR & DHT Fractionator Furnace Control





APC can control the FD inlet damper opening and cold air damper inlet to HCR

Fractionator Heater & DHT Fractionator Reboiler Furnaces to maintain excess air.

4.7 HARDWARE / INSTRUMENT / PROCESS ISSUES OR CONSTRAI NTS

In the above, issues on hardware, instruments and process that can hamper successful

implementation of APC and prevent achieving of the projected APC benefit in HCU &

DHT units of the BORL were described. BORL has confirmed that these will be attended

before APC implementation and are listed below:

1. At present, Density & ASTM distillation data of only Blended HCR Diesel, final DHT

Diesel and combined KERO are taken. Density & ASTM distillation data of Diesel &

KERO at the HCR & DHT Fractionator product ends (before any mixing) are also

needed. KERO analysis should include Flash Point also.

2. At present, there is flow meter in the HN line going to the Diesel Blend, and no Flow

Control Valves in the HN & KERO lines going to the Diesel Blend. These are needed

for accurate control of Diesel blending.

3. The VFD AC fans at the top of HCR & DHT Strippers should be made available for

manipulation by APC in order to recover LPG.





5.0 Quantification of Expected Economic Benefit

5.1 Benefi t Estimation Method

The approach taken in APC study follows the commonly used method for the estimation of

the benefits generated by APC, which is schematically represented in Figure 3.1. By

stabilizing the process unit, APC enables a controlled variable to be operated closer to its

specification. Any process variable, during a given time period, can be described through a

statistical model in terms of its average value and standard deviation. By reducing the

standard deviation, APC allows the operator to move the average value closer to the fixed

limit, by set point adjustment, while the risks of temporary violations are constant or

reduced. The difference between the average qualities before and after the implementation

of APC can be translated into quantifiable benefits such as product yields and hence into

economic benefits. To visualize how reduced variance allows closer approach to targets

and constraints consider the following diagram:

105

104

103

102

101

100

99

98

97

96

95

94

93

92

91

90

BEFORE CONTROL ADV ANCE D

CONTROL ON-LINE

EXPLOITATION -

SET POINT MOVED

CLOSER T O LIMIT

P E R C E N T O F L I M I T

Distribution of

Instantaneous values

SPECIFICATION

CONSTRAINT

QUALITY LIMIT, ETC

BEST OPERATOR

PERFORMANCE

A

B

Quality improvement through variance reduction

Figure 5.1

The graph represents the variation of some important process variable relative to a

constraint over a certain operating period. These variations can be represented by the so-

called normal “Gaussian” distribution as indicated in the right hand side of the above





figure. The tolerable frequency of constraint violation is determined by operational

experience and consequently sets the operating target with a certain comfort level below

the constraint (first part of the diagram). Modern APC techniques will stabilize the process

variations (second part of the diagram) and push the average operating point closer to the

constraint in such a way that the frequency of constraint violation remains the same (third

part of the diagram). The calculated economic impact of the shift of the mean closer to the

optimum operating point is then claimed as a benefit attributable to APC. Note the

reduction of the size of the violation after APC is put on-line at the same frequency of

violation (refer to the above figure). This effect will sometimes allow the constraint or

specification to be relaxed a little bit, increasing APC incentives further. However, to stay

rather conservative, this additional benefit is generally not accounted for in APC studies.

Experience shows that, depending on the application, advanced control can reduce the

standard deviation by 20-90% compared to the normal DCS control.

The actual calculation of APC benefit is carried out through the following steps. As a first

step, data collected during major process upsets are first discarded. Then, the SD (Standard

Deviation) is calculated using the formula given in Microsoft Excel. For those data that

should always remain within a range, e.g., Laboratory data, data values that differ form the

average value by certain magnitude (e.g., ± 2*SD) are considered out-liars and excluded

from the data. Then, the SD shall be re-calculated. The amount that the process variable

can be pushed towards constraint by use of APC can be found by using the statistical

formula, namely “The Same Limit Rule” (Ref: Hydrocarbon Processing, June 1991, Pg.

69):

x = k * (S-Sc)

where,

x = distance / gap the process variable can be moved towards constraint.

S = SD of process variable without APC in line

Sc= SD of process variable with APC in line

K = factor depends on the frequency of violation of process variable

If the violations are allowed 20% of the time then k = 0.8



If the violations are allowed 2.3% of the time then k = 2.0





Experience shows that most of the commercially available control systems show constraint

violations up to 5% of the time if plant is running below its designed capacity. Therefore,

x = 1.65* (S – Sc ) …(1)

Once the improvement

x in the value of parameter is found out as above, it can becorrelated to the economic driver attached to the improvement in parameter and we can

then quantify the APC benefit.

Since HCU & DHT plants are running close to 115% & 120% capacity respectively at

present, many process variables are at their operating constraints and the probability

of constraint violation is more. Apart from this, due to strong interactions between

controlled variables, product quality and operating constraints, the feasible reduction

in standard deviation will be less than predicted by the above equation. Benefits have

been calculated by taking these limitations into consideration.

5.2 Basis for Benefi t Estimation

As mentioned in Section 1, Process and Laboratory data over the period of 1st july 2013 to

30th august 2013 were collected to establish a baseline performance of existing processcontrol system and estimate the performance improvement benefit that can be expected

from APC. All the Laboratory data were filtered such that values outside the range ± 2*SD

(where, SD = standard deviation) are excluded as outliers. The Price data provided by

BORL is shown below.

Product Unit Price

IFO Rs/ MT 48061LPG Rs/ MT 50613.33

Light and Heavy Naphtha Rs/ MT 52804.67

Kerosene Rs/ MT 57449.36

HSD (Euro- III) Rs/ MT 55383.27

UCO Rs/ MT 48146.15

Steam Rs/ MT 2373

Fuel Gas Rs/ MT 57673.2

Electricity Rs / Unit 7.16

Additional data that were supplied by BORL are:





Variable Name Unit Value

Minm. HCR Diesel Density MT/m3 0.82

Minm. DHT Diesel Density MT/m3 0.824

Minm. Blended Diesel Density MT/m3 0.8225

Calorific Value of FG Kcal / MT 12000000

Feed Sp. Heat Kcal /MT/ oC 687.5

Latent Heat of Steam Kcal / MT 570000

It is further assumed that working hours per year is 8000.





5.3 Quanti fi cation of Benefits for HCR-DHT Section

5.3.1 Maximization of LPG

APC will control and maximize LPG production at Debutanizer, by controlling thetemperature profile and reflux in the Debutanizer column, HCR & DHT Stripper columns.

APC will also control Sponge Oil Absorption column conditions for the same reason so

that carryover of LPG components to sour gas is minimized. The VFD AC fans at the top

of HCR & DHT Strippers should be made available for manipulation by APC. The first

part of LPG yield maximization is based on lifting heavy Light Naphtha components into

the LPG stream. The second part of LPG yield maximization is based on capturing

heavy C3/C4 components in the Off-gas into LPG. However, this part could not be

estimated properly due to absence of C3/C4 component data in Off-gas. Due to

operating / hardware constraints, effective changes have been limited to 25% in the first

case. The calculation procedure would be as follows:

Std. Devn. in LN D5 v% Point = 2.2966 °C

Slope between LN D5 & IBP v% Points = 2.3138 °C / v%

Av. LN Flow = 36.3382 MT/hr

Av. LPG Density = 0.545 MT/m3

Av. LN Density = 0.6858 MT/m3

Increase in LN D5% based on Std. Devn. = 0.25*1.65*(2.2966-0.75*2.2966) = 0.2368 °C

Decrease in LN v% due to increase in LN D5% = 0.2368/2.3138 = 0.1024 v%

Decrease in LN volm. Flow = (0.1024/100)*(36.3382/0.6858) = 0.0542 m3/hr

Corresponding Increase in LPG volm. Flow = 0.0542 m3/hr

Corresponding Increase in LPG mass flow = 0.0542*0.545 = 0.0296 MT/hr

Av. HCR+DHT Feed Flow = 475.2827 MT/hr

Increase in LPG Yield due to lifting from LN = 0.0296*100/475.2827 = 0.0062 %

Please, note that exact correlation between LPG Weathering and LN D5% could not be obtained

based on the available data. The present av. LPG Weathering is -0.37. Increase in LN D5% by

0.2368 °C is expected to increase LPG Weathering by a fraction of 0.2368 °C. Hence, LPG

weathering is expected to remain below +2 °C. Furthermore, when APC will be implemented, it

will maintain LPG Weathering within a specified range.

Price of LPG = 50613.33 Rs/MT

Price of LN = 52804.67 Rs/MT

Price of FG = 57673.2 Rs/MT

Differential Price (LPG-LN) = Negative

Differential Price (LPG-FG) = Negative

Working Hours 8000 hr/yr

Av. HCR+DHT Flow = 475.2827 MT/hr

Benefit from increase of LPG yield by pulling from LN = Cannot be estimated due to negative

differential price (LPG-LN)

While maximizing LPG, Naphtha has been minimized by extracting light components as

much as possible into the LPG stream. The decrease in Naphtha yield achievable iscalculated as follows:





Decrease in LN (Light Naphtha) volm. Flow (as calculated above) = 0.0542 m3/hr

Av. LN Density = 0.6858 MT/m3

Corresponding decrease in SN mass flow = 0.0542*0.6858 = 0.0372 MT/hr

Av. HCR+DHT Flow = 475.2827 MT/hr

Decrease in Naphtha Yield = 0.0372*100/475.2827 = 0.0078 %

5.3.2 Maximization of HCR Diesel

APC will try to control and optimization Diesel production at the individual Fractionator

column of HCR. For implementation of this strategy, ASTM distillation data of HCR

Diesel & KERO at the HCR Fractionator product end are needed. At present ASTM

distillation data of only Blended HCR Diesel and combined KERO is taken. APC can also

try to maximize proportion of UCO, HN & KERO in Blended HCR Diesel. However, for

implementation of this strategy, flow control valve is needed in the HN and KERO

blending line. At present, flow control valve is present only for UCO blending line. Anestimate of the benefit, assuming these issues get resolved, is as follows:

HCR Diesel can be maximized by dropping heavy KERO components into Diesel and

lifting light UCO components into Diesel. The reliable method for estimating HCR Diesel

yield increase for these two cases under present circumstances is the use of HCR Diesel

ASTM curve at light & heavy ends. Since distillation data of only Blended HCR Diesel is

available, ASTM data of the later will be used as an approximation for HCR Diesel. In

order to keep critical process constraints like draw temperatures and product qualities

satisfied, and due to operating / hardware constraints, effective changes have been limited

to 25%. The calculation procedure would be as follows:

Std. Devn. in HCR Diesel D05 v% Point = 8.1596 °C

Av. Slope between HCR Diesel IBP – D10 v% Points = 2.7904 °C / v%

Std. Devn. in HCR Diesel D95 v% Point = 4.0094 °C

Av. Slope between HCR Diesel FBP - D90 v% Points = 1.8247 °C / v%

Av. light HCR Diesel Flow = 83.7995 MT/hr

Av. heavy HCR Diesel Flow = 76.4826 MT/hr

Av HCR Diesel Flow = 83.7995+76.4826 = 160.2821 MT/hr

Av. KERO Density = 0.7842 MT/m3

Av. HCR Diesel Density = 0.8209 MT/m3


Decrease in HCR Diesel D05 v% based on Std. Devn. = 0.25*1.65*(8.1596-0.75*8.1596) = 0.8415 °C

Increase in HCR Diesel v% due to decrease in HCR Diesel D05 = 0.8415/2.7904 = 0.3016 v%

Decrease in HCR Diesel volm. Flow =(0.3016/100)*(160.2821/ 0.8209) = 0.5888 m3/hr

Corresponding influx of KERO into HCR Diesel = 0.5888 m3/hr

Corresponding KERO volm. Fracn. In HCR Diesel = 0.5888/((160.2821/0.8209)+ 0.5888) = 0.003

Corresponding HCR Diesel Density = (1-0.003)*0.8209+0.003*0.7842 = 0.8207 MT/m3

Minm. Specification of HCR Diesel Density = 0.82 MT/m3

Allowed Increase in HCR Diesel volm. Flow by KERO dropping = 0.5888 m3/hr

Corresponding increase in HCR Diesel mass flow = 0.5888*0.8209 = 0.4833 MT/hr

Increase in HCR Diesel Yield due to dropping KERO = 0.4833*100/475.2827 = 0.1017 %





Increase in HCR Diesel D95 v% based on Std. Devn. = 0.25*1.65*(4.0094-0.75*4.0094) = 0.4135 °C

Std. Devn. in HCR Diesel D95.5 v% Point = 4.2334 °C

Corresponding increase in HCR Diesel D95.5% = 0.25*1.65*(4.2334-0.75*4.2334) = 0.4366 °C

Maximum Allowed value of HCR Diesel D95.5% = 360 °C

Present Av. value of HCR Diesel D95.5% = 357.3012 °CAllowed increase in HCR Diesel D95.5% = min(0.4366, (360-357.3012)) = 0.4366 °C

Allowed increase in HCR Diesel D95% = 0.4135 °C

Increase in HCR Diesel v% due to increase in HCR Diesel FBP = 0.4135/1.8247 = 0.2266 v%

Increase in HCR Diesel volm. Flow = (0.2266/100)*(160.2821/0.8209) = 0.4424 m3/hr

Corresponding increase in HCR Diesel mass flow = 0.4424*0.8209 = 0.3632 MT/hr

Increase in HCR Diesel Yield due to lifting UCO = 0.3632*100/475.2827 = 0.0764 %

Total increase in HCR Diesel Yield = 0.1017+0.0764 = 0.1781 %

Price of KERO = 57449.36 Rs/MT

Price of Diesel = 55383.27 Rs/MTPrice of UCO = 48146.15 Rs/MT

Differential Price (Diesel-KERO) = Negative

Differential Price (Diesel-UCO) = 7237.12 Rs/MT

Working Hours = 8000 hr/yr

Benefit from KERO Dropping into HCR Diesel = Cannot be estimated due to negative differential

price

Benefit from UCO Lifting into HCR Diesel = 0.3632*8000*7237.12/100000 = 210.2706 Lakh Rs/yr

Total Benefit = 210.2706 Lakh Rs/yr

While maximizing HCR Diesel, Kerosene and UCO have been minimized above bydropping heavy components of KERO and lifting light components of UCO respectively

into HCR Diesel. The decrease in KERO & UCO yields achievable is calculated as

follows:

Increase in HCR Diesel volm. Flow by KERO dropping (as calculated above) = 0.5888 m3/hr

Corresponding decrease in KERO volm. flow = 0.5888 m3/hr


Corresponding decrease in KERO mass flow = 0.5888*0.7842 = 0.4618 MT/hr


Decrease in KERO Yield due to dropping into HCR Diesel = 0.4618*100/475.2827 = 0.0972 %

Increase in HCR Diesel volm. Flow from UCO Lifting (as calculated above) = 0.4424 m3/hr

Corresponding decrease in UCO volm. Flow = 0.4424 m3/hr

Av UCO Density = 0.8382 MT/m3

Corresponding decrease in UCO mass flow = 0.4424*0.8382 = 0.3709 MT/hr


Decrease in UCO Yield = 0.3709*100/475.2827 = 0.078 %





5.3.3 Maximization of DH T Diesel

APC will try to control and optimize Diesel production at the Fractionator column of DHT.

For implementation of this strategy, ASTM distillation data of DHT Diesel & KERO at the

DHT fractionator product end are needed. At present ASTM distillation data of only final

DHT Diesel and combined KERO is taken.

DHT Diesel can be maximized by dropping heavy DHT KERO components into Diesel.

The reliable method for estimating HCR Diesel yield increase under present circumstances

is the use of DHT Diesel ASTM curve at light end. In order to keep critical process

constraints like draw temperatures and product qualities satisfied, and due to operating /

hardware constraints, effective changes have been limited to 25%. The calculation

procedure would be as follows:

Std. Devn. in DHT Diesel D05 v% Point = 4.3119 °C

Av. Slope between DHT Diesel D10 - IBP v% Points = 4.7014 °C / v%

Av DHT Diesel Flow = 189.3609 MT/hr


Av. DHT Diesel Density = 0.8243 MT/m3


Increase in DHT Diesel D05 v% based on Std. Devn. = 0.25*1.65*(4.3119-0.75*4.3119) = 0.4447 °C

Increase in DHT Diesel v% due to decrease in DHT Diesel D05 = 0.4447/4.7014 = 0.0946 v%

Increase in DHT Diesel volm. Flow = (0.0946/100)*(189.3609/0.8243) = 0.2173 m3/hr

Corresponding influx of KERO into DHT Diesel = 0.2173 m3/hr

Corresponding KERO volm. Fracn. In DHT Diesel = 0.2173/((189.3609/0.8243)+ 0.2173) = 0.0009

Corresponding DHT Diesel Density = (1-0.0009)*0.8243+0.0009*0.7842 = 0.8243 MT/m3

Minm. Specification of DHT Diesel Density = 0.824 MT/m3

Allowed Increase in DHT Diesel volm. Flow by KERO dropping = 0.2173 m3/hr

Corresponding increase in DHT Diesel mass flow = 0.2173*0.8243 = 0.1791 MT/hr

Increase in DHT Diesel Yield = 0.1791*100/475.2827 = 0.0377 %

Price of KERO = 57449.36 Rs/MT

Price of Diesel = 55383.27 Rs/MT

Differential Price (Diesel-KERO) = Negative


Benefit from KERO Dropping into DHT Diesel = Cannot be estimated due to negative differential

price

While maximizing DHT Diesel, Kerosene has been minimized by dropping its heavy

components as much as possible into DHT Diesel. The decrease in KERO yield achievable

is calculated as follows:

Increase in DHT Diesel volm. Flow by KERO dropping (as calculated above) = 0.2173 m3/hr

Corresponding decrease in KERO volm. flow = 0.2173 m3/hr

Corresponding decrease in KERO mass flow = 0.2173*0.7842 = 0.1704 MT/hrDecrease in KERO Yield due to dropping into DHT Diesel = 0.1704*100/475.2827 = 0.0358 %





Total Decrease in KERO Yield due to dropping in HCR & DHT Diesel = 0.0972+0.0358 = 0.133 %

5.3.4 Maximization of Heat Recovery in F/E Exchangers

The temperature controllers of the F/E Exchangers before the reactor furnaces (FF101 &FF201) are to be set such that the temperature difference across Furnace is around 22oC on

average. However, there is some variation in this temperature difference. Since APC can

reduce such variations by consistently maintaining the Furnace temperature difference at a

fixed value, heat recovery can be maximized. Since this benefit is based on the DCS

control as reference, the range of Furnace temperature difference under APC has to

be around the average Furnace temperature difference under DCS control to realize

this benefit. For example, the available data indicates that the present average values of

Furnace temperature differences under DCS control are below 22oC. In such a case, if APC

ranges are set around the higher value of 22oC for operational reasons, then obviously

energy consumption will increase in Furnaces instead of decreasing. We can consider this

as an “F/E Heat Recovery OFF” case in which the following benefit calculation

calculations cannot be used. Hence, during Post-Audit, this benefit can be estimated

and added to the total benefit only for “F/E Heat Recovery ON” case in which the

ranges of Furnace temperature differences under APC control are set around the

average values under DCS control. Due to operating / hardware constraints, effective

changes have been limited to 25%. The calculation procedure would be as follows:

FF101 TDI (Temp. Diff., 16TDI1601.PV) Mean = 18.306 °C

FF101 TDI STD = 2.3843 °C

Decrease in FF101 TDI based on Std. Devn. = 0.25*1.65*(2.3843-0.75*2.3843) = 0.2459 °C

Feed Liq to FF101 = 256.0477 T/hr

Feed Gas to FF101 = 30584.332 KG/hr

Total Feed to FF101 = 256.0477+30.5843 = 286.632 T/hr

Cp of Feed = 687.5 Kcal/T/ °C

Heat Requirement Decrease in Feed to FF101= =286.632*687.5*0.2459 = 48453.18 Kcal / hr

Calorific Val. of FG = 12000000 Kcal /T

Decrease in FG to FF101 = 48453.18/12000000 = 0.004 T/hr

FF201 TDI (Temp. Diff., 16TDI2603.PV)Mean = 19.358 °C

FF201 TDI STD = 1.7283 °C

Decrease in FF201 TDI based on Std. Devn. = 0.25*1.65*(1.7283-0.75*1.7283) = 0.1782 °C

Feed Liq to FF201 = 200.7894 T/hr

Feed Gas to FF201 = 18759.8633 KG/hr

Total Feed to FF201= 200.7894+18.7599 = 219.5493 T/hr

Cp of Feed = 687.5 Kcal/T/ °C

Heat Requirement Decrease in Feed to FF201= =219.5493*687.5*0.1782 = 26902.2 Kcal / hr

Calorific Val. of FG = 12000000 Kcal /T

Decrease in FG to FF101 = 26902.2/12000000 = 0.0022 T/hr

Total Decrease in FG = 0.004+0.0022 = 0.0063 MT/hr

Price of FG = 57673.2 Rs/MT






Benefit from maintaining Furnace Temperature Difference = 0.0063*8000*57673.2/100000 =

28.9732 Lakh Rs/yr

5.3.5 Maximization of Steam Generation in H eavy Diesel Pump-Ar ound circui t

The temperature controller around the Steam Generator in Heavy Diesel PA (Pump-

Around) circuit is presently set at a fixed temperature. For controlling column temperature

profile, the heat removal in PA circuit or equivalently PA temperature difference can be

controlled. However, there is some variation in the Pump-Around temperature difference.

Since APC can reduce such variations by consistently maintaining the Pump-Around

temperature difference within a fixed range, steam generation can be maximized. Due to

operating / hardware constraints, effective changes have been limited to 25%. The

calculation procedure would be as follows:

Heavy HCR Diesel PA TD (Temp. Diff., [16TI6007.PV] - [16TIC6801.PV]) Mean = 89.9259 °CHeavy HCR Diesel PA TD STD = 3.0953 °C

Decrease in Heavy HCR Diesel PA TD based on Std. Devn. = 0.25*1.65*(3.0953-0.75*3.0953) =

0.3192 °C

Heavy HCR Diesel PA Flow = 213.0396 T/hr

Cp of Feed = 736 Kcal/T/ °C

Increase in Heat available for Steam Generation in Heavy HCR Diesel PA circuit =

213.0396*736*0.3192 = 50050.0899 Kcal / hr

Latent Heat of Steam = 570000 Kcal / T

Increase in Steam Generation in Heavy HCR Diesel PA circuit = 50050.0899/570000 = 0.0878 T/hr

Price of Stm. = 2373 Rs/MTWorking Hours = 8000 hr/yr

Benefit from Stm. Generation in Heavy HCR Diesel PA circuit = 0.0878*2373*8000/100000 =

16.6693 Lakh Rs/yr

5.3.6 Excess Ai r M in imization in HCR Fractionator Heater & DHT Reboil er Furnaces

(With in Al lowable Range)

APC can control the FD fan speed and cold air damper inlet to HCR Fractionator Heater &

DHT Fractionator Reboiler Furnaces to maintain excess air. Due to operating / hardware

constraints, effective changes have been limited to 25%. The calculation procedure would be as follows:

Stoichiometric Coeff. w.r.t. FO in FF501 = 1.7258 M3/KG

Stoichiometric Coeff. w.r.t. FG in FF501 = 2.4798 M3/KG

Av. Excess O2 in FF501 = 3.2822 %

STD of Excess O2 in FF501 = 1.5134 %

Decrease in Excess O2 in FF501 based on STD = 0.25*1.65*(1.5134-0.75*1.5134) = 0.1561 %

Maxm. Allowed Decrease in Excess O2 in FF1501 (final Excess O2 > 2%) = 3.2822-2 = 1.2822 %

Decrease in Excess O2 in FF501 w APC = 0.1561 %

Av. FG flow in FF501 = 2415.2517 KG/hr

Av. FO flow in FF501 = 2527.5376 KG/hrAv. Air flow in FF501 = 62002.1602 M3/hr





Air flow in FF501 w APC ~ 62002.1602*(1-0.1561/100) = 61905.3938 M3/hr

FO flow in FF501 w APC

= 2527.5376+(1/1.7258)*(61905.3958/(1+(3.2822-0.1561)/100)-62002.1602/(1+3.2822/100))

= 2525.809755 KG/hr

Reduction in FO w APC = 2527.5376 – 2525.8098 = 1.7278 KG/hr

Stoichiometric Coeff. w.r.t. FG in FF701 = 1.6091 KG/KG

Av. Excess O2 in FF701 = 2.2376 %

STD of Excess O2 in FF701 = 1.5178 %

Decrease in Excess O2 in FF701 based on STD = 0.25*1.65*(1.5178-0.75*1.5178) = 0.1565 %

Allowed Decrease in Excess O2 in FF701 w APC (final Excess O2 > 2%) = 2.2376-2 = 0.2376 %

Decrease in Excess O2 in FF701 w APC = 0.1565 %

Av. FG flow in FF701 = 563.9006 KG/hr

Av. Air flow in FF701 = 12596.4268 KG/hr

Air flow in FF701 w APC ~ 12596.4268*(1-0.1561/100) = 12576.7105 KG/hr

FG flow in FF2 w APC

= 563.9006+(1/1.6091)*(12576.7105/(1+(2.2376-0.1565)/100)-12596.4268/(1+2.2376/100))= 563.6379 KG/hr

Reduction in FG w APC = 563.9006-563.6379 = 0.2627 KG/hr

FO Price = 48061 Rs/MT

FG Price = 57673.2 Rs/MT


Benefit from Excess Air Minimization

= (1.7278/1000)*48061+(0.2627/1000)*57673.2)*8000/100000 = 7.8554 Lakh Rs/yr

5.3.7 Control & Optimization of Gas-to-Oil Ratio in HCR 1st Stage (Within Al lowableRange)

At present, GOR (Gas-to-Oil Ratio) of HCR 1st & 2nd Stages are monitored through DCS

display. GOR is important for maintaining required H2 partial pressure in the reactors to

serve the desired reaction kinetics. There are variations in these ratios. By maintaining it at

an optimum value within an allowable range, it is possible to minimize Recycle Gas

consumption and hence the consumption of HP steam used to drive the RGC. As

mentioned in Section 4.1, only the 1st stage GOR will be optimized to remain at an

optimum value. In other words, minimization of GOR is expected to be achieved indirectly

by keeping it at an optimum value within the range of its normal variations. Due tooperating / hardware constraints, process interactions and the optimization difficulty, the

effective change has been limited to 10%. The calculation procedure would be as follows:

HCR 1st Stg. GOR Mean = 966.375

HCR 1st Stg. GOR STD = 204.9201

Decrease in HCR 1st Stg. GOR based on STD = 0.1*1.65*(204.9201-0.75*204.9201) = 8.453

Gain between HCR 1st Stg. GOR DCS-display unit and Direct KG/T unit = 0.12433

Decrease in HCR 1st Stg. GOR in Direct Kg/T unit = 8.453*0.12433 = 1.051 KG/T

Av Value of HCR 1st Stg. HC Feed = 256.0477 T/hr

Feasible decrease in HCR 1st Stg. Recycle Gas = 256.0477*1.051 = 269.0948 KG/hr

Gain of Recycle Gas and HP Steam Consumption in RGC = 0.00027106 T/KG





Decrease in HP Steam Consumption in RGC = 269.0948*0.00027106 = 0.0729 T/hr

Price of Steam = 2373 Rs/MT


Benefit from GOR minimization within allowable range = 0.0729*8000*2373/100000

= 13.8471 Lakh Rs/yr





5.4 Total Expected APC Benefi t

5.4.1 Total Expected APC Benef it in HCR-DH T Section

The list of benefits calculated above for HCR-DHT section is summarized below:

Table 5.4.1

Benefit Area

Percentage

Yield

Change

(wherever

applicable)

Benefit Estimate

Rs Lakh / Yr

LPG Maximization 0.0146 %

Increase

Benefit based on:

Pulling LN components cannot be estimated due to negative

differential priceTotal = 0 Lakh Rs / yr

Naphtha Minimization 0.0078 %Decrease

Already accounted through the LPG Benefit above

HCR DieselMaximization

0.1781 %Increase

Benefit based on:

1. Pulling KERO components cannot be estimated due to

negative differential price

2. Pulling UCO components = 210.27 Lakh Rs / yr

Total = 210.27 Lakh Rs / yr

DHT Diesel

Maximization

0.0377 %

Increase

Benefit based on:

1. Pulling KERO components cannot be estimated due to

negative differential priceTotal = 0 Lakh Rs / yr

KERO Minimization 0.133%

Decrease

Already accounted through the HCR & DHT Diesel Benefits above

UCO Minimization 0.078 %Decrease

Already accounted through the HCR Diesel Benefit above

Maximization of

Steam Generation in

Heavy Diesel PA

circuit

16.67

Excess Air

Minimization in HCR

Fractionator Heater &

DHT ReboilerFurnaces

7.86

Optimization of 1st

Stage GOR

13.85

Total Benefit (F/E

Heat Recovery OFF)

248.64

Maximization of Heat

Recovery in F/E

Exchangers

28.97

Total Benefit (F/E

Heat Recovery ON)

277.62

The total benefit can also be expressed in Cent/Barrel as follows:

Basis of Cent/Barrel Benefit = Total Feed to HCR & DHTAv. HCR Feed Flow (16FIC1601.PV) = 256.0477 MT/hr





Av. DHT Feed Flow (16FIC3701.PV) = 219.2354 MT/hr

Av. HCR Feed Density = 0.9166 MT/m3

Av. DHT Feed Density = 0.8490 MT/m3

Av. HCR Feed Flow (volume) = 256.0477/0.9166 = 279.3352 m3/hr

Av. DHT Feed Flow (volume) = 219.0477/0.8490 = 258.2329 m3/hrAv. HCR+DHT Feed Flow (volume) = 279.3352+258.2329 = 537.5682 m3/hr

1 Barrel = 0.15899 m3

1 Cent = 0.6 Rs

Total Benefit (F/E Heat Recovery OFF case) =

(248.64*100000)*0.15899/((537.5682*8000)*0.6) = 1.53 Cent/Barrel

Total Benefit (F/E Heat Recovery ON case) =

(277.62*100000)*0.15899/((537.5682*8000)*0.6) = 1.71 Cent/Barrel

Hence, the total HCR & DHT APC benefit is estimated here as:

- 2.49 Crore Rs/Yr or 1.53 Cent/Barrel (When F/E Heat Recovery is not

realized)

- 2.78 Crore Rs/Yr or 1.71 Cent/Barrel (When F/E Heat Recovery is realized)





6.0 Instrumentation & Hardware Requirement for DCS Connectivity

with APC

In BORL-Bina, HGU & HCR-DHT units are equipped with Yokogawa Centum

CS3000 DCS system for centralized operation and monitoring of the unit. The APC

system and verticals connectivity with the DCS has to be established using a

dedicated ExaOPC station resting on the V-net/IP network as shown in the below

diagram. Keeping in view DCS network loading, a dedicated ExaOPC is

recommended for the project (APC Implementation in HGU & HCR-DHT Units)

to enable the APC and RQE Controllers (Yokogawa APC Application or any Third

Party APC Application) to communicate with the DCS Network for seamless

bidirectional data transfer which is essential for APC Implementation.

This proposed ExaOPC Gateway shall cater to handling process data from the

HGU and HCR-DHT Units. It is recommended to deploy separate dedicated

ExaOPC Gateways to facilitate the APC-DCS Communication for the same.

With OPC, any third party system can acquire and define process data from CS3000

& and receive alarm events. It supports OPC standard interface functions(DA/A&E/HDA) specified by OPC Foundation, and many other optional

functional such as browsing.

Data Access (DA) Server (in-built under ExaOPC Gateway)

The DA Server reads and writes process data using item IDs as identifiers.

Alarms & Events (A & E) Server (in-built under ExaOPC Gateway)

The A&E Server notifies alarms and events from plants that asynchronously occur

Historical Data Access (HDA) Server (in-built under ExaOPC Gateway)

OPC automatically saves instantaneous values acquired from the DA Server, to a

historical database in the HDA Server. The OPC client can access historical data by

connecting to the HDA Server. A list of tags in CS 3000 can be equalized to OPC.

Users can view the content of the OPC from OPC client. The OPC client can access

CENTUM tag list that OPC acquired by Equalization functions. To prevent





problems, access from the client is restricted to avoid exceeding the maximum

accessible data. The OPC package provides the OPC client with an interface with

the following specifications:

OPC has passed the OPC DA2 Compliance Test. The ExaOPC Station being

supplied will be the latest version available and is DA3 Compliant.

DA Server Cassette Specification

OPC Data Access Custom Interface Specification Version 2.05a or above

OPC Data Access Automation Specification Version 2.0 or above

OPC Security Custom Interface Specification Version 1.0 or above

A&E Server Cassette Specification

OPC Alarms and Events Version 1.02

OPC Alarms and Events Automation Specification Version 1.0 (draft)

OPC Security Custom Interface Specification Version 1.0

HDA Server Cassette Specification

OPC Historical Data Access Custom Interface Version 1.1

OPC Historical Data Access Automation Interface (Version 1.0 draft)

Advantages of using ExaOPC station

a. Since it is directly connected to the control bus data availability can be

guaranteed at all the times irrespective of any Operator station failures, moreover

there is no need to write any user programs for gathering or setting the data to /

from DCS. All DCS information (real time data / Engineering data) is available at

all times at the bus speed.

b. In case of Tag List change ExaOPC station senses, equalizes it’s own database

and the same trigger can be used by client programs to update the Tag Lists.

c. ExaOPC is OPC server, which satisfies the OPC Standards; hence existing DCS

system becomes truly ‘OPEN’ with any third party OPC client.

d. Data thru put is as high as 1000 data per second.

e. Multiple clients can access the DCS data at their own interval.





f. Data Quality is maintained throughout the network. Each information is

associated with the Time stamp and the Quality flag.

6.1 Recommended System Architecture for APC System

The proposed System Architecture while implementing APC in HGU & HCR-DHT

units has been shown below:

Figure 6.1





7.0 Technical Specifications

HARDWARE REQUIREMENTS (Per Unit)

(a) Hardware Requirements for HCR-DHT:

S.No HARDWARE Type of Application Qty.

1 Online APC Server To be supplied by APC vendoras per APC Application

1

2 Offline APC Server To be supplied by APC vendoras per APC Application

1

(b) Additional Common Hardware Requirements for HGU and HCR-DHT**

S.No HARDWARE Type of Application Qty.

1 ExaOPC Gateway Proprietary to Yokogawa 12 Network Switch for APCComputers

To be supplied by APC vendor 1

**Note:- This has already been accounted for in the HGU Scoping Study Report.

1. Specifications for Online APC Computer (Server Range) – Qty. - 1No

Make: HP / DELL /IBM

S.No Item Requirement

1 Processor Dual Intel® XeonTM Processor 3.4 GHz or faster.2 RAM 4 GB, expandable to 8 GB minimum

3 Hard Disk 5x 80 GB minimum – RAID 5 w/online spare (6x1”) hot pluggable drive bays minimum

4 RAID Controller Smart Array 5302/128 Controller (RAID)

5 Monitor 17” TFT Monitor

6 CD-ROM/DVD CD-DVD + RW 16X Drive minimum

7 Network Card 3 Gigabit Network cards, Minimum two free PCI slots and

one free PCI Express slot minimum

8 Operating

System

Windows 2008 server (having downgrade option to Windows

2003 server) with media or latest Windows Operating Systemsupporting MVPC, IPP and other APC software includinginterface software.

9 MS Office and

Antivirus

MS Office 2010 and Symantec Antivirus and Antispywaresoftware with subscription till end of AMC.

10 Comprehensive

support

Till the end of AMC





11 Supplies and

Accessories

Hot plug redundant power supply, supporting 100-240V input power, hot plug redundant Fans, keyboard, mouse, USB ports,and CAT-6 cable (10feet) with RJ-45 connector.

2. Specifications for Offline APC Computer – Qty. - 1No

Make: HP / DELL /IBM

S.No Item Requirement

1 Processor Intel® Processor 2.4 GHz or faster

2 RAM 4 GB, expandable to 8 GB minimum

3 Hard Disk 3x80 GB minimum

4 Monitor 17” TFT Monitor

5 CD-ROM/DVD CD-DVD + RW 16X Drive minimum

6 Network Card 2, Gigabit Network cards

7 Operating

System

Windows 2008 server (having downgrade option to

Windows 2003 server) with media or latest Windows

Operating System supporting MVPC, IPP and other

APC software including interface software.

8 MS Office and

Antivirus

MS Office 2010 and Symantec Antivirus and

Antispyware software with subscription till end of

AMC.

9 Comprehensive

support

Till the end of AMC

10 Supplies and

Accessories

Supporting 100-240V input power supply, Keyboard,

mouse, USB ports, MS Office 2010, Symantec

Antivirus and Antispyware software with subscription

till end of AMC.

** Note: Latest available PC model/Other Hardware will be purchased and

delivered during the project execution.





SOFTWARE REQUIREMENTS (Per Un it)

(a) Software Requirements for HCR-DHT:

S. No. SOFTWARE Type of Application

1MVPC and Robust Quality

Estimator OnlineTo be supplied by APC vendor as

per APC Application

2MVPC and Robust Quality

Estimator OfflineTo be supplied by APC vendor as

per APC Application

3 APC-DCS Interface

Development ***Proprietary to Yokogawa

***Note: The APC-DCS Interface is imperative to the smooth and reliable operation of

APC Controllers. The Interface comprises of:-

1) supervisory and interlocks logic that need to be created in the DCS Controller

(FCS) for safe switchover from APC mode to DCS Control mode on account of any

emergency in Plant Operations or any other Operations requirement.

2) DCS Graphics to enable the Operator to perform APC Monitoring by entering the

MV Limits, CV Limits etc. to ensure smooth operation of the Plant

This would require additional resources to be created in the FCS (DCS Controller) and

engineering to be done to implement Interlock logics and also any ERC (Enhanced

Regulatory Control) strategies if required for better control.

Keeping in mind the criticality of the Interface for reliable and safe operations and also

mitigate any risks/delays that may arise in the later stages of Project Execution due to

insufficient knowledge on Yokogawa’s Centum CS3000 DCS System by any other APC

Vendor it is recommended that Yokogawa carry out this activity.

(b) Additional Common Software Requirements for HGU and HCR-DHT:**

S. No. SOFTWARE Type of Application

1 ExaOPC Application Package Proprietary to Yokogawa

**Note:- This has already been accounted for in the HGU Scoping Study Report.





8.0 Project Execution & Schedule

The project goes through the following steps.

8.1 Kick-Off Meeting (KOM)

It is proposed that the project KOM be held at BORL-BINA, as soon as possible

after the issue of the LOI. This meeting shall discuss in detail about project

organization, communication channels and the detailed project schedule.

8.2 Process Study

A detailed study of the plant is made. APC engineers collect any necessary

documents and data required and interact with Technical & Operation group to

obtain a full understanding of the process. The Process and Lab data (for the period

June to October, 2013), which were shared by BORL to YIL during Scoping Study

visit and the data based on which the Benefit estimate has been obtained in this

Report, shall be designated as the Base Case data of the project. This data shall be

used to establish the guaranteed benefit achieved by APC during Post-Audit.

8.3 Pretest

Following Base Case Study, Pretest is to be completed. The scope of Pretest is

primarily to check all the applicable DCS level regulatory controls, to make sure

they are configured properly and controlling adequately for the application of the

Advanced Process Control. Thus, PID (Proportional Integral Derivative) controller

loops critical for APC performance are examined and re-tuned if necessary.

Malfunctioning of existing instruments and need for additional instruments, which

are critical for APC application, are identified. All the controlled, manipulated and

disturbance variables are identified.

Following Pretest, a FDS (Functional Design Specification) is submitted by the

APC consultant for review of the customer. FDS is a preliminary design document

for the proposed APC system. Once FDS is approved by the customer, APC





consultant submits for approval a Step Test plant, indicating how the Steptest will

be conducted.

On the other hand, the customer should rectify the malfunctioning instrument and

provide the additional instrumentation identified before Step Test can begin.

8.4 Steptest

Following Pretest, Steptest is to be completed. Steptest is required for developing

dynamic models for the SMOC applications. During Steptest, inputs to the process

will be changed several times in both direction and the response will be noted. Data

of Steptest will be collected using the data historian software.

8.5 Engineering

There will be a complete Engineering of the APC system following Pretest &

Steptest, involving the following activities at the APC Vendor site:

Identification of Process Models

− Estimation of Model Parameters

− Model Validation

− Adequacy Check

Development of Quality Inference Models

− Estimation of Model Parameters

− Model Validation

− Adequacy Check

Controller Development based the models and offline simulation and tuning of

the controller

FAT (Factory Acceptance Test) based on off-line simulation for various test

conditions/scenarios

There will be following additional engineering activities at customer site before

commissioning:





Supply & Installation of all Hardware & Software

− Either before or after the Steptest, all the necessary APC & OPC

hardware and software need to be installed and kept ready before APC

commissioning.

APC Graphics & Interface Development

− CV/MV/DV tables with entries necessary to run APC from DCS are

created

− DCS switches and logic are created that will enable safe run of APC

from DCS (for example, facility to switch off APC following

communication problem or plant emergency and bumpless transfer from

APC to full DCS control)

8.6 Commissioning

After completing the activities above, APC commissioning activity at customer site

starts. During commissioning, APC loops are tuned online to make then work

satisfactorily. Any changes are incorporated in the final design document known as

DDS (Detailed Design Document) that is submitted after commissioning for

customer review.

8.7 Site Activity Test (SAT)

SAT is scheduled following commissioning. In this activity, APC run for about 15

to 30 days and closely observed to check any run time problems. The on-line factor

(i.e., the percentage of time that APC run uninterruptedly) is calculated. During this

period, the percentage confidence limits of quality inferentials (i.e., the percentage

deviation of model prediction from Laboratory data) are also checked.

8.8 Post-Audit

Post-Audit is scheduled following SAT. In this activity, APC run data are collected

over 7 days. These data are compared to the Base Case data and the APC benefit

achieved is calculated. A Post-Audit Report is submitted.





A tentative schedule of all activities is attached in Fig. 9.1. Normally,

commissioning is completed in eight months after obtaining the work order. 15 to

30 days post-commissioning is earmarked for SAT activity, following which Post-

Audit activity is taken up.

S.

No.

ACTIVITY FROM DATE OF

ISSUE OF LOI / PO / WO

No.

of

Mo. 1 2 3 4 5 6 7 8 9 10

1 KOM & Process Study 1

2Pretest, PID Tuning &

Pretest Report1

3 FDS Report 1

4 Supply & Installation ofHardwares & Softwares

0.5

5 Step Test 1.5

6Model & Inferential

Development1.5

7 FAT 0.5

8 Interface Development 0.5

9 Commissioning 1

10DDS & DCS Interface

Document1

11 SAT 1

12Post Audit & Post-Audit

Report0.5

Figure 8.1





9.0 Training Requirement

True success of any APC project is possible through synergy between BORL and

APC engineers. Therefore training shall be completed as early as possible

(preferably, before Steptest, or at least during FAT activity) in order to enable

BORL engineers to appreciate and involve fully in all activities of APC

implementation. BORL console officers shall also be trained before the APC is put

online.

The Engineering Training should be a comprehensive one and should cover design

aspects of APC. There are several advantages of comprehensive Engineering

Training:

1. BORL engineers can exploit advanced features of APC available at APC server,

such as on-line APC tuning, changing priority among controlled variables.

2. BORL engineer can quickly restore the system after communication or power

failure.

3. It becomes easy for BORL to look after the APC system.

4. BORL engineers can use the design tools themselves and modify APC design if

necessary.

The Operator Training should focus on the APC operational aspects; so that console

officers can change the variables provided in the APC graphics and obtain the

desired results. It is also necessary to train the operators on the followings:

1. Which Manipulated Variables (MV) are used by APC to control each

Controlled Variable (CV).2. Any specific requirement when switching between DCS and APC control.

3. What to do when CV or MV hit their limits.

A minimum of 6 engineers are given engineering training over a span of five days

and this training can be held at the APC vendor’s office. The operator training is

held prior to APC commissioning at site, and normally requir es only a 2 hours’

session. The console officers of the control room, where APC system has beencommissioned, are enrolled for the operator training.





10.0 Approximate Cost EstimationThe cost components in the HGU & HCR-DHT APC project are tabulated below in

Table 11.1 & 11.2. These are divided into proprietary and non-proprietary items.

Table 10.1 Bill of Materials for APC System in HCR-DHT Unit

Applicable for HCR-DHT Unit

S. No Item Quantity

1

Hardware for APC (Minimum Spec)

1 LotOffline Server (4 GB, 160GB HDD, R/W CD Drive) : 1 No.

Online Server (4 GB, 160 GB HDD, CD Drive) : 1No.

2

Software Suite for APC

1 Lot

SMOC Offline Package: 1No.

RQE Offline Package: 1No.

ExaSMOC (online) Package : 1 No.

ExaRQE (online) Package : 1 No.

3 APC Engineering 1 Lot

Base case preparation

Engineering

a. Pre-test

b. Step Test

c. RQE Model Development

d. SMOC Model Development

e. Controller commissioning and tuning

4APC-DCS Interface Development(Proprietary to

Yokogawa)1 Lot

5 Training 1 Lot

6 Documentation 1 Lot

7 Site Commissioning 1 Lot

8 SAT & Post Audit 1 Lot

9

Post-Warranty AMC Contract for APC

a. Service Contract

b. Software Upgrade Contract (Optional)

1 Lot





The estimated cost for the APC systems are tabulated below.

Table 10.2 Estimated Costs of APC System for HCR-DHT (As per BOM Table

10.1)

S. No. Item Price INR

1 Hardware (Item No - 1 of BOM) 1500000.00 Fifteen Lakhs

2 Software (Item No - 2 of BOM) 6000000.00 Sixty Lakhs

3 Training (Item No - 6 of BOM) 500000.00 Five Lakhs

4 Implementation (Item- 3,6,7,8-BOM) 3000000.00 Thirty Lakhs

5 APC-DCS Interface

Development(Item No 4 of BOM)

*(Proprietary to Yokogawa)

1500000.00 Fifteen Lakhs

Total 12500000.00 One Hundred

& Twenty Five

Lakhs

5 AMC Service Contract in Cost / Year

(Item No. – 9a of BOM)

1000000.00 Ten Lakhs

6. AMC Software Upgrade Contract

(Optional) in Cost / Year (Item No. –

9b of BOM)

1500000.00 Fifteen Lakhs

*Note: The price for the required EXAOPC Gateway and Network Switch for APC-

DCS communication is already furnished in the HCU Scoping Study Report. Since the

HCU-DHT and HGU Units shall have a common EXAOPC Gateway the prices are

given along with the HGU Scoping Study report and hence not explicitly mentioned in

this report.



**Note: All the above prices for APC Hardware, APC Software, APC

Implementation, ExaOPC Hardware, Software and Implementation are exclusive of

taxes. The taxes applicable and terms & conditions of this proposal are indicated

below:-

Taxes Excise Duty

CST

Service Tax

Extra as applicable at the time of delivery. Present rateis 12.36% for hardware items .Software does notattract Excise Duty.

Extra as applicable at the time of delivery.

Present rate is 2% on basic + excise duty for Hardware

and 2% on Software basic price.

Extra as applicable at the time of delivery.

Present rate is 12.36% on basic prices of Services. Statutory Variation Any Statutory variation for taxes and duties mentioned

above shall be borne by customer Price Validity 60 days from the date of the Proposal.

Documents

BORL HCU-DHT APC Scoping Study Report (Final)