Tower , Furnace & SoakingDrum
cleaning & inspection
cleaning & inspection

A) Hydro mechanical decoking of fired heater tubes

 

The method of mechanical decoking with flexible scraper is well and is widely applied at the oil/gas process plants worldwide to deal with decoking and removal of petroleum coke and -inorganic deposits from the coil-tubes inner surface in the fired heaters/furnaces of oil refining and petrochemical plants.

The major benefits of pipe mechanical decoking at oil refining and petrochemical plants are:

* High cleaning efficiency

* Reduction of work performance time

* Safety of work performance

* Significant economy of energy resource during decoking

* This method guarantees removal of extraneous objects from inside heater tubes sections, which could have been left during first installation or annual maintenance and which cannot be removed with steam-air decoking methods.

* An option to complement the procedure of mechanical decoking with ultrasonic probe inspection.

Cleaning of tubes is performed initially with first run spongy scrapper and then with the cleaning scrapper inside pipes. Geometry of scrapper pins is of major importance for its performance.

 

Characteristics of coked pipe:

* Increase of firing fuel consumption cost

* Decrease of process performance

* Pipe life time reduction

* Increase of service frequency

* Decrease of pipe remaining life

* High pipe surface temperatures. High initial coking level

 

Advantages of hydro mechanical decoking:

* Complete extraction of all coke inside the system, inclusive convection section

* Reduction of off period for service activities

* No high temperature

* Ecologically safe

* No mechanic and temperature damages of pipes during decoking

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                Before Cleaning                                                                   After Mechanical Decoking

 

 

 Decoking of return bends, plug headers, u-bends, mule ears

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Condition of heater tubes before and after cleaning

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                                       Typical launcher system hook-up                  Launch of the scrapper

 

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                                                                 Before                                                         After

 

 

ID 89 and ID 141 mm process tubes, convection, pyrolysis heater

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                                             Before                                                                    After

Visbreaker unit heater, radiant outlets

 

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Coke deposits taken (on the right in the launcher)

 

Hydro mechanical decoking allows to renew the initial design capacity in heater passes flows, extruding during the first decoking physical obstacles, remains of rebar, pipes, which commonly remain after initial installation.

Absence or reduction of depositing in convective and radiant fired heater tubes allows to increase performance of oil processing heaters due to increase of their performance through heating of hydrocarbons under optimal temperature and pressure condition; meanwhile the outcome of end products is increased.

 

Fireside tubes cleaning online

Combined technology of fire heater tube outer surface cleaning online

Online chemical cleaning of fire heater tube external surface is the most economically worth wile and reasonable means of heater maintenance with further high heater performance.

The latest 20 years saw successfully application of this technology at overseas oil refineries, petro chemistry enterprises in the chemical industry, and it has been actively integrated in the world.

What problems do the clients face?

One may face the following problems during exploitation of fire heaters and waste heat boilers:

* Decrease of flue gas (draft)

* Decrease of pipe heat conductivity

* High flue gas  temperatures

* Decrease of productivity

* Increase of fuel consumption

* High and low temperature pipe corrosion, which leads to burn-out, sagging and pipe breakage

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Advantages of chemical treatment against ordinary steaming:

* Less maintenance shutoff time (due to reduction of entry time and mechanical cleaning time)

* Lower inflammation risks

* Lower steam and water consumption

* Facilitation of further mechanical cleaning from coke, non-organic and hydrocarbon deposits

* Wide application area-this method can be applied (when washing with water and steaming)

* Fast and safe preparation of equipment for opening

* Saving of plant resource

* Personnel security

 

Technology of outer surface cleaning online

Ensures efficient solution of equipment usage problems without shutdown connected losses using special purpose chemicals.

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External cleaning works include:

1. Injection of chemical into the flow of heater/boiler flue gas.

2. Removal of loose deposits by blow off with compressed air if access holes are available or application of stationary soot blowing system.

3. Blasting cleaning with soft abrasive (dry granulate).

Average cleaning time for one heater or waste heat boiler is four to six days.

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 Before                                                                    After

 

Outside cleaning in shut off mode

Operation principle:

Efficiency of this method is guaranteed by the chemical reagents which react with deposits in tube surface (sage, ash, Sulphur compounds), and pass a part of its kinetic energy to deposit particles without damaging the pipes and heater, tank and boiler equipment.

 

Column Gamma Scanning online

Gamma scanning is applied for inspection of fractionating columns at oil refineries, petrochemical and chemical manufactories. it allows to detect internal mechanical damages and defects in technologic process during its operation.

 

Column performance related problems

There may arise some failures in operation of column equipment the reasons of which are difficult to determine without shutoff and opening of column. Reasons for such failures may comprise destruction of inside apparatus (plates, caps), down flow weir blocks,carry over and flooding.

Gamma scanning has been successfully implemented for inspection of column equipment for over 15 years. the information collected during gamma scanning allows to gain better understanding of equipment operation, analyse existing problems,track possible repeated undesirable effects and help to adjust operation.

Description of Gamma scanning method

Scanning of a column is performed with a small power radio nuclear gamma source and a sensor.

Density profile is the result of such gamma scanning.

Diagnostics is performed in column operating mode with no interference into technologic process.

The information thus received can become the basis for such key decisions as further operation or shutoff of the column.

Application

* Problems with contamination and inorganic polymer deposits, problems of inside effects and flooding.

* Temperature and raw materials consumption connected operation defects.

* Optimization of equipment operation.

* Defects research and analysis.

* Pre-maintenance evaluation of the scope of mechanic damage with the purpose to prepare resource for reduction of equipment downtime during maintenance.

* Problems with start- up

* control emergency columns.

 

Gamma scanning results allow to:

Determine:                                                                                                       supervise:

* Mechanic damages of internal construction elements                 * Efficiency of taken measures

(destruction of caps and plates)                                                  * Amplification of adverse effects

* Flooding, carry over soakage or scumming                                * Unit performance

* Level of liquid in the bottom of column                                              To be scheduled:

* Changes in technologic process                                               
   in different operation modes                                   *  Purchase of components for fast and breakdown repair

                                                                               *  Maintenance

To be detected:                                                        * Equipment operation mode

* The reason of malfunction                                       * Development of new modification

* Temperature problems

* Change of exploitation characteristics

To be evaluated:

* Scope of damage

* Location of defects

 



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