logo
Banner pic

Main Automation and APC Technology

SME in the field of instrumentation including temperature, pressure, flow, and analytical instruments. All instrumentation must pass inspections as a prerequisite before any work on APC can begin. SME in the field control valves including valve sizing, positioner selection, and integration into any DCS IO, Foundation Field bus design, Alarm/Trip Summary, Specifications, Selection & Sizing of flow /level/control valves, Instrument Layouts, Instrument Hookups, Instrument JB / Marshalling / IO.

Termination Panel Wiring drawings, Logic Narrative, Logic Diagrams, Cause & Effect Matrix, Complex Control loops, using SEE and AUTOCAD. Installed and commissioned and maintained the following Gas Chromatographs, UV/IR Continuous Gas Analyzers, Paramagnetic Continuous Gas Analyzers, FTNIR, CEMS, pH & conductivity, TOC, Zirconium Oxide /Catalytic Bead stack analyzers.

PLATFORM FOR IMPLEMENTING ADVANCED CONTROLS

All basic and traditional Advanced Controls (e.g. cascade, feedforward, de-coupling, inferential and constraint controls, etc.) will be implemented on the DCS. While inferential calculations and MPC-based control applications (e.g. data acquisition, MPC controls, and dynamic simulation) will be implemented in a host engineering PC interfaced with the DCS. The Engineering computer will be interfaced with the DCS. It will also be interfaced with a PC to provide bi-directa ional transfer of files between the host computer and a PC. Custom schematics will be provided for operator monitoring of laboratory data. Application programs running in the PC ENGINEERING computer will access the laboratory data via the DCS Database.

ACSC will provide the refinery client with a license to use the following proprietary software Technology.

• PC ENGINEERING computer – DCS interface software

• MPC Control package

• MPC simulation Package for control engineer’s interface with and tuning of the MPC controller, as well as for operator training.

• Data Acquisition Package

• Inferential Quality Control Package.

• Crude Switching Quality Control Package.

• MPC–DCS interface software.

• Software for the bi-directional file transfer between the host computer and PC.

• Identification Package to generate dynamic models from process data tests.

• The client will be required to sign a secrecy agreement to use these packages.

Typical Scope of Crude (CDU) Unit project on any underlining site-wide DCS System:

CDU Advanced Control Objectives:

  • Maximize the charge rate to the crude unit while honoring all unit constraints, when the economic climate requires operating the unit at maximum throughput.
  • Maximize the lifting of Atmospheric Reside to Heavy Diesel (HD) and Light Diesel (LD).
  • Maximize the lifting of Vacuum residue to HVGO.
  • Reduce quality giveaway on Naphtha ASTM EP, thus allowing increased Naphtha yield without violating its ASTM EP constraint.
  • Improve the separation in the CDU towers by reducing the variability of Flash Zone Pressures and operating at minimum pressures limited by tower constraints.
  • Reduce the giveaway in CDU product quality during Crude Switching
  • Reduce i-C5 losses in the LSRN Stabilizer Overhead and the giveaway on the Stabilizer bottoms Reid Vapor Pressure (RVP).
  • Reduce energy consumption by reducing excess O2 in F1101A and F1101B Fuel Gas;  maintaining preheat trains and heater pass outlet temperatures equal, and optimizing the pump around heat duties.
  • Reduce the giveaway in Fuel Oil viscosity.
  • Increase Naphtha Splitter throughput limited by tower constraints and reduce the tower operating pressure to improve separation and reduce energy consumption.
  • Maximize i-C6 in Naphtha Splitter overhead and n-C6 in the Splitter bottoms.

VDU Advanced Control Objectives

  • Maximize the charge rate to the VDU while honoring all unit constraints,  when the economic climate requires operating the unit at maximum throughput.
  • Maximize the lifting of Vacuum Rresidueto HVGO.
  • Reduce the giveaway on Fuel Oil viscosity.
  • Improve the separation in the VDU by reducing the variability in tower pressure and operating at minimum pressures limited by tower constraints.
  • Reduce energy consumption by equalizing or balancing the vacuum heater passes outlet temperatures and reducing excess oxygen in the heater stack.
  • MOD Blending Unit Advanced Control Objectives
  • Optimize the blending of CDU Kerosene, L, D, and HD; VDU LVGO; and HDC diesel to maximize MOD production and reduce vacuum Reside production.
  • Reduce the giveaway on MOD product quality by the online blending of CDU Kerosene, LD and HD, VDU LVGO, and HDC Diesel.

Unifier Unit Advanced Control Objectives:

  • Reduce the variability in Unifier product sulfur to improve overall hydrotreated Naphtha yield and unit throughput.
  • Maximize Unifier Unit throughput constrained by unifier reactor temperature, H2 availability, circulation, heaters loading, etc to process the additional feed resulting from the anticipated increase in Naphtha production.
  • Maintain H2-to-Oil ratio between specified limits to maintain optimum Reformate catalyst aging rate and minimize H2 recycle compressor power consumption.
  • Reduce the giveaway on hydrotreated Naphtha RVP by allowing more butane in the Naphtha Stabilizer bottoms limited by the RVP specification.
  • Reduce i-C5 losses in the Naphtha Stabilizer overhead to maximize Naphtha yield.
  • Reduce Naphtha Stabilizer pressure, limited by the condenser’s capacity, to improve Naphtha yield and reduce energy consumption.
  • Maximize Unifier throughput.
  • Provide the refinery with the capability to process more high-sulfur low-cost crude.

Reformer Unit Advanced Control Objectives:

  • Reduce Reformate octane variability to improve overall Reformate yield.
  • Maximize the reformer unit throughput constrained by the reformer reactors temperature, H2 availability, circulation, heaters loading, etc to process the additional Naphtha resulting from the implementation of CDU, VDU, HDC, and MOD blending Advanced Control.
  • Increasing the Reformer throughput will be achieved mainly by reducing the variance in Reformate octane and operating the unit close to constraints, rather than operating at some safe distance from constraints in anticipation of large upsets.
  • Maintain H2-to-Oil ratio between specified limits to maintain optimum Reformer catalyst aging rate and minimize H2 recycle compressor power consumption.
  • Minimize Reformate reactor pressure to increase Reformate yield.
  • Reduce the giveaway on Reformate RVP by allowing more butane in the Reformate Stabilizer Bottoms limited by Reformate RVP specification.
  • Reduce i-C5 losses in the Reformate Stabilizer Overhead to maximize Reformate yield.
  • Reduce Reformate Stabilizer tower pressure, limited by the condenser’s capacity, to improve Reformate yield and reduce energy consumption.
  • Minimize de-euthanized overhead pressure constrained by condenser duty to improve LPG yield and reduce energy consumption.

Isomerization Unit Advanced Control Objectives:

Maximize unit throughput, yield, and product octane. This is achieved mainly by:

  • Monitoring isomer rate yield, feed composition, and charge rate and proper adjustment of the SAFE CAT reactor and adsorption section temperatures to maintain sulfur in the hydrotreated product between 0.1 to 0.2-wt%.
  •  Proper adjustment of Total Isomerization Process (TIP) reactor temperature and adsorber section cycle timer setting and flows to optimize the trade-off between increasing unit yield and improving product octane.
  • Provides the refinery with the capability to process more high-sulfur low-cost crude feed

Utility Boilers and Steam and Electricity Distribution Advanced Control Objectives.

  • Improve Steam and Utility Boilers efficiencies. Although the refinery is using economizers to preheat combustion air and improve heater efficiency, some of the heaters are operating at high excess O2.  Heater efficiency can be improved further by reducing excess air.
  • Optimize steam generation and distribution will conserve energy by reducing energy losses in the let-down stations, optimizing load distribution between the boilers, and reducing steam headers pressures.
  • Optimum electricity distribution will allow efficient use of the turbo generators and reduce grid electricity consumption.

2.0 CDU, VDU, HDC, and MOD BLENDING ADVANCED CONTROL APPLICATIONS

It is recommended to implement CDU, VDU, HD, C, and MOD blending in steps.

  • The first step is to install traditional and inferential Advanced Controls on the CDU, VDU, HDC, and MOD blending units. These are required to be installed and operational before implementing MPC controls.
  • The next step is to install three MPC controllers on the CDU, VDU, the Naphtha Splitter, and the LSRN stabilizer.  Three stand-alone controllers are recommended; one on the LSRN Stabilizer and the Naphtha Splitters, and one stand-alone controller on the CDU and VDU.  The stabilizer and splitter controllers will produce immediate benefits including reducinggiveawaysy on RVP, reducing i-C5 losses to LPG; maximizing n-C6 in the Naphtha Splitter bottoms, and i-C6 in the Splitter overhead.
  • The third step is to install MPC on the HDC Fractionation section.  Three stand-alone controllers are recommended; one on the product Fractionator, one on the debutanizer, and one on the Naphtha Splitters.  These controllers will produce immediate benefits including reducing the giveaway on Naphtha and Diesel quality.  Further benefits include maximizing the lifting of PF bottoms to diesel, reducing HDC Fractionation section energy consumption, reducing giveaway on HDC Naphtha RVP, reducing i-C5 losses to LPG, maximizing n-C6 in the Naphtha Splitter bottoms and i-C6 in the splitter overhead.
  • The fourth step is to install the HDC MPC reactor temperature controllers. A single controller will be applied for the 1st and 2nd stage reactors.  These controllers will stabilize the reactors’ operation and maximize the HDC throughput while honoring all equipment constraints and hydrogen availability. 
  • The last step is to install MOD online blending and optimization controls.

 2.1 Overview of Traditional and Inferential Control Applications

CDU, VDU, HDC, and MOD Blending Traditional and Inferential Advanced Control applications that maximize the yield of MOD and Naphtha, minimize energy consumption and maximize unit throughput are discussed individually in Section 5.7 of this document.  

These applications will be implemented mostly on the client’s Yokogawa DCS, with Inferential and other calculations done in the engineering WSPCr and will include:

Atmospheric Crude Unit Controls:

  • Desalter pressure control and crude preheat train temperature balancing.
  • Crude charge pump speed control.
  • Crude charge flow control and heaters’ pass balancing.
  • Crude heaters’ combustion control using available stack O2 analyzers.
  • Crude heaters’ combustion control using stack O2 and CO analyzers (for future application
  • Crude heaters’ outlet temperature control.
  • Top Pump Around duty control.
  • Mid Pump Around duty control.
  • Kerosene stripper’s Steam-to-Oil ratio control.
  • Lt. Diesel stripper’s Steam-to-Oil ratio control.
  • Heavy Diesel stripper’s steam-to-oil ratio control.
  • Naphtha ASTM End Point control.
  • Kerosene 95% ASTM BP control.
  • Light Diesel 95% ASTM BP control.
  • Heavy Diesel 95% ASTM BP control.
  • Over flash control.
  • CDU Overhead pressure minimization constraint pushing control.
  • Product quality and pump-around control during crude switches.

Vacuum Unit Controls

  • VDU charge flow control and heaters’ pass balancing.
  • Vacuum heater combustion control using available stack O2 analyzer.
  • Vacuum heater combustion control using stack O2 and CO analyzers (for future application).
  • Vacuum heater outlet temperature control.
  • VDU Top Pump Around duty control.
  • VDU Mid Pump Around duty control.
  • LVGO 95% ASTM BP controls.
  • HVGO 95% ASTM BP controls.
  • Over flash control.
  • Overhead pressure minimization constraint pushing control.

HDC Unit Controls

  • HDC charge control and heaters’ pass balancing.
  • HDC charge heater combustion control using available stack O2 analyzer.
  • HDC charge heater combustion control using stack O2 and CO analyzers (for future application).
  • HDC charge heaters’ outlet temperature control.
  • HDC PF charge control and heaters’ pass balancing.
  • HDC PF charge heater combustion control using available stack O2 analyzer.
  • HDC PF charge heater combustion control using stack O2 and CO analyzers 
  • HDC PF charge heaters’ outlet temperature control.
  • HDC NS reboiler flow control and heaters’ pass balancing.
  • HDC NS reboiler combustion control using available stack O2 analyzer.
  • HDC NS reboiler combustion control using stack O2 and CO analyzers 
  • HDC NS reboiler outlet temperature control.
  • Top Pump Around duty control.
  • Mid Pump Around duty control.
  • Kerosene stripper’s Steam-to-Oil ratio control.
  • Diesel stripper’s Steam-to-Oil ratio control.
  • HDC Naphtha ASTM End Point control.
  • HDC Kerosene 95% ASTM BP control.
  • HDC Diesel 95% ASTM BP control.
  • Hydrogen-to-oil ratio control.
  • HDC hydrotreating reactor bed inlet temperature control
  • HSRN stabilizer and HDC dehumanizer Bottoms RVP Inferential calculation.
  • CDU and HDC naphtha splitter overhead I-C6 inferential calculation
  • CDU and HDC naphtha splitter  bottoms n-C5 inferential calculation

MOD Blending Controls Simulation RESULTS using ACSC TECHNOLOGY

  • Online blending of CDU Kerosene, LD, HD, and VDU LD and HDC Kerosene and Diesel, using online Diesel 95 % BP analyzer and laboratory cold properties data.
  • MOD Blending Optimization.

Table 5.2.1

CDU, VDU, HDC, and MOD Blending Simulation Results – Base Case

 

CDU Naphtha CDU Kerosene CDU LD CDU HD CDU Resid VDU LVGO
Flow 181 43.6 104 104 268.2 14
Sp. Gravity 0.7145 0.78 0.8126 0.8567 0.957 0.861
ASTM 90% 155 198 263 352 370
ASTM 95% 162 204 273 367 388
ASTM EP 172 217 292 393 417

 

VDU HVGO VDU Resid HDC Naphtha HDC Kerosene HDC Diesel MOD Blending
Flow 93.2 106.4 20.34 17.5 51 335
Sp. Gravity 0.9068 1.014 0.737 0.815 0.831
ASTM 90% 495 146 228 378 347.2
ASTM 95% 507 237 385 365.5
ASTM EP 527 259 396 393.4

Table 5.2.2

CDU, VDU, HDC, and MOD Blending Simulation Results – Optimum Case

 

CDU Naphtha CDU Kerosene CDU LD CDU HD CDU Resid VDU LVGO
Flow 191.3 50.4 99 105 357.5 19.1
Sp. Gravity 0.716 0.7844 0.8276 0.862 0.9367 0.866
ASTM 90% 159 206 272 369 728 381
ASTM 95% 168 213 281 386 762 399
ASTM EP 179 226 300 413 825 430

 

VDU HVGO VDU Resid HDC Naphtha HDC Kerosene HDC Diesel MOD Blending
Flow 101.6 92.9 22.17 19 55.6 348.2
Sp. Gravity 0.916 1.028 0.737 0.815 0.831 0.83
ASTM 90% 522 136 228 378 351.7
ASTM 95% 536 145.9 237 385 369.9
ASTM EP 556 259 396 393.4

View ACSC Qualifications

View SIS PRESENTATION OUTLINE HLT

View Service

View Safety Checklist