what is feedback and feed forward control?

Feedback:
          Control action after an error exists.
Feed forward:
           Reacting to the disturbance before the  error occurs.

Mechanical/ Instrumentation Technicians wanted for Saudi Arabia

Aljabar Talke Group

A Multinational Co. Specialized in Chemical Logistics 
Operations Requires Below Manpower in Jubail.

Technicians - Mechanical/ Instrumentation

Qualification: Diploma in Mechanical/ Instrumentation

Experience: Minimum 3 years experience knowledge of Safety & MS Office application.

Location: Saudi Arabia

Client Interview in Delhi on 12th & 13th March 2014

Nasser Overseas Consultants
502/B, Savoy Chambers, 5th Floor, 
Linking Road, Near Juhu Garden, 
Opp. Masjid, Santacruz (W), Mumbai - 54 
Ph.: 022 - 6195 7500, 09819018298, 09833832163 

Intimation No. 40021400

Lic. No: B-0137/MUM/PER/1000+/3/263/84

FLUOR MIDDLE EAST JOBS

                              FLUOR MIDDLE EAST JOBS


Instrumentation & Controls Commissioning Engineer- KSA        click here for apply online

Commissioning Engineer/Specialist I                         - KSA         click here for apply online  

Designer, Instrumentation                                          - KSA         click here for apply online  

Control Systems Engineer                                         - KSA         click here for apply online  

Control Systems Engineer - Loop Check                  - KSA         click here for apply online  

Control Systems Engineer - Loop Check                  - KSA         click here for apply online  

Shell Recruitment - Instrument technician for Basra Iraq

Shell Recruitment - Instrument technician   for   Basra  Iraq


                                               click here for apply online
    Shell Iraq Pretroleum Development Company (SIPD) is committed to supporting the development of the Iraqi oil and gas industry. In 2013, Shell will invest more than US$1 billion in developing an oil field in Iraq. At Shell, your ideas will travel. This is reflected in Shell’s industry-leading career development programme that sees its employees thrive and take advantage of Shell’s unrivalled local and global experts. Shell Companies in Iraq provide a technically challenging work environment characterised by operational excellence and new ways of working. Our work environment and culture rewards innovation, collaboration and long-term commitment.

SOS-CO QATAR SHUTDOWN JOBS

SOS-CO QATAR SHUTDOWN JOBS

VACANCIES IN QATARGAS

VACANCIES IN QATARGAS   click here for apply online

FOR ONLINE APPLY	POSITION	JOB ID
FOR INTERVIEW	PROCESS ENGINEER	GG13301
FOR INTERVIEW	PLANT INSPECTOR	GG13302
FOR INTERVIEW	QA / QC ENGINEER	GG13303
FOR INTERVIEW	SENIOR CORROSION ENGINEER	GG13304
FOR INTERVIEW	SENIOR PIPELINE INTEGRITY ENGINEER	GG13305
FOR ONLINE APPLY	CORROSION INSPECTOR	GG13306
FOR ONLINE APPLY	INSTRUMENT & CONTROL ENGINEER	GG13307
FOR ONLINE APPLY	MATERIALS & CORROSION ENGINEER	GG13308
FOR ONLINE APPLY	MEASUREMENT ENGINEER	GG13309
FOR ONLINE APPLY	FIELD INSPECTOR	GG13310
FOR ONLINE APPLY	FIELD INSPECTOR	GG13310

:: JOB ORDER NO. GG138 ::

FOR ONLINE APPLY	POSITION	JOB ID
FOR INTERVIEW	ROVER OPERATOR LNG PROCESS	GG13801
FOR INTERVIEW	ROVER OPERATOR INLET RECEIVING	GG13802
FOR INTERVIEW	ROVER OPERATOR SRU	GG13803
FOR INTERVIEW	ROVER OPERATOR UTILITIES	GG13804
FOR INTERVIEW	ROVER OPERATOR CLNG - STORAGE AND LOADING	GG13805
FOR ONLINE APPLY	SENIOR LABORATORY TECHNICIAN	GG13806
FOR ONLINE APPLY	SENIOR INSTRUMENT TECHNICIAN	GG13807
FOR ONLINE APPLY	SENIOR OPERATOR	GG13808
FOR ONLINE APPLY	SENIOR LABORATORY OPERATOR	GG13809
FOR ONLINE APPLY	SENIOR ELECTRICAL TECHNICIAN	GG13810
FOR ONLINE APPLY	SENIOR MECHANICAL TECHNICIAN	GG13811

VACANCIES IN QATARGAS   click here for apply online

What is a Refinery?

Inside a maze of silver towers and pipes is a fascinating factory that changes hydrocarbon
molecules to make gasoline.

A refinery is a factory. Just as a paper mill turns lumber into legal pads or a
glass works turns silica into stemware, a refinery takes a raw material--crude oil--
and transforms it into gasoline and hundreds of other useful products.
A typical large refinery costs billions of dollars to build and millions more to
maintain and upgrade. It runs around the clock 365 days a year, employs
between 1,000 and 2,000 people and occupies as much land as several
hundred football fields. It's so big and sprawling, in fact, that workers ride
bicycles from one station to another.

Gasoline's lowly status rose quickly after 1892, when Charles Duryea built the
first U.S. gas-powered automobile. From then on, the light stuff from crude oil
became the right stuff.
Today, some refineries can turn more than half of every 42-gallon barrel of
crude oil into gasoline. That's a remarkable technological improvement from 70
years ago, when only 11 gallons of gasoline could be produced. How does this
transformation take place? Essentially, refining breaks crude oil down into its
various components, which then are selectively reconfigured into new products.
This process takes place inside a maze of hardware that one observer has
likened to "a metal spaghetti factory." Employees regulate refinery operations
from within highly automated control rooms. Because so much activity happens
out of sight, refineries are surprisingly quiet places. The only sound most visitors
hear is the constant, low hum of heavy equipment.

The complexity of this equipment varies from one refinery to the next. In
general, the more sophisticated a refinery, the better its ability to upgrade crude
oil into high-value products. Whether simple or complex, however, all refineries
perform three basic steps: separation, conversion and treatment.

Separation:  heavy on the bottom, light on the  top

Modern separation--which is not terribly different from the "cooking" methods used at the        Pico Canyon stills--involves piping oil through hot furnaces. The resulting liquids and vapors are discharged into distillation towers, the tall, narrow columns that give refineries their distinctive skylines. Inside the towers, the liquids and vapors separate into components or fractions

according to weight and boiling point. The lightest fractions, including gasoline and liquid

petroleum gas (LPG), vaporize and rise to the top of the tower, where they condense back to

liquids. Medium weight liquids, including kerosene and diesel oil distillates, stay in the

middle. Heavier liquids, called gas oils, separate lower down, while the heaviest fractions with the highest boiling points settle at the bottom. These tarlike fractions, called residuum, are literally the "bottom of the barrel."

The fractions now are ready for piping to the next station or plant within the refinery. Some components require relatively little additional processing to become asphalt base or jet fuel. However, most molecules that are destined to become high-value products require much more processing.

Conversion:  cracking and rearranging molecules to add value

            This is where refining's fanciest footwork takes place--where fractions from the distillation towers are transformed into streams (intermediate components) that eventually become finished products. This also is where a refinery makes money, because only through conversion can most low-value fractions become gasoline.

       The most widely used conversion method is called cracking because it uses heat and pressure to "crack" heavy hydrocarbon molecules into lighter ones. A cracking unit consists of one or more tall, thick-walled, bullet-shaped reactors and a network of furnaces, heat ex-changers and other vessels.

           Fluid catalytic cracking, or "cat cracking," is the basic gasoline-making process. Using intense heat (about 1,000 degrees Fahrenheit), low pressure and a powdered catalyst (a substance that accelerates chemical reactions), the cat cracker can convert most relatively heavy fractions into smaller gasoline molecules.

            Hydrocracking applies the same principles but uses a different catalyst, slightly lower temperatures, much greater pressure and hydrogen to obtain chemical reactions. Although not all refineries employ hydrocracking, some of industry leader in using this technology to cost-effectively convert medium- to heavyweight gas oils into high-value streams. The company's patented
hydrocracking process, which takes place in the Isocracker unit, produces mostly gasoline and jet fuel.Some refineries also have cokers, which use heat and moderate pressure to turn residuum into lighter products and a hard, coal like substance that is used as an industrial fuel. Cokers are among the more peculiar-looking refinery structures. They resemble a series of giant drums with metal derricks on top. Cracking and coking are not the only forms of conversion. Other refinery
processes, instead of splitting molecules, rearrange them to add value. Alkylation, for example, makes gasoline components by combining some of the gaseous byproducts of cracking. The process, which essentially is cracking in reverse, takes place in a series of large, horizontal vessels and tall, skinny towers that loom above other refinery structures. Reforming uses heat, moderate pressure and catalysts to turn naphtha, a light, relatively low-value fraction, into high-octane gasoline components. Chevron's patented reforming process is called Rheniforming for the rheniumplatinum catalyst used.