Progress Report 4

Steam Reformer

Yousef Alhannoush, 200900150

AR-RAZI, SABIC Company

Mechanical Engineering Department, Engineering College, Prince

Mohammed University (PMU)

1

Summary

In the previous weeks, I visited the plant with one of the inspector engineers in order to see the revamp for the steam reformer. I went to see the catalyst tube, the catalysts, and the main components of the reformer. This report will cover in brief the definition, design, failures, inspection, revamp, start up, and shutdown of the reformer. This report is to show AR-RAZI professionalism in maintaining high levels of safety, reliability, and structure integrity. Background

All AR-RAZI plants are in Jubail industrial city, in the eastern province of Saudi Arabia.

It is not the only company who produces methanol; however, it is the biggest company to

produce methanol in the kingdom. The first plant was fully established in 1983. After

eight years, the second plant was constructed and followed by the third plant in 1997. The

fourth plant started to produce methanol in 1999. This plant is considered to be the

biggest plant in AR-RAZI Company. AR-RAZI is considered to be the largest single

complex methanol production plant in the world. The company has other facilities but it

is not as big as these plants. In this report, I will present the type of the corrosion that

they usually face, the prevention of corrosion, and the inspection equipment used.

ProgressThrough out my visiting to the plant for several times to see and to learn about steam

reformer as well as asking the inspectors and the mechanical engineers about it in details

and taking the specialized manual. Through this report I will show what I learned by

detailed information:

IntroductionIn the previous weeks, I visited the plant with one of the inspector engineers in order to see the revamp for the steam reformer. I went to see the catalyst tube, the catalysts, and the main components of the reformer. This report will cover in brief the definition, design, failures, inspection, revamp, start up, and shutdown of the reformer. This report is to show AR-RAZI professionalism in maintaining high levels of safety, reliability, and structure integrity. Definition

2

o Steam formers are used widely in the petrochemical industry to produce hydrogen from hydrocarbons.

o Steam reformer is a device used in chemical plants. o The steam reformer is one of the main essential equipment in methanol

and ammonia production plants.o The steam reformer is utilized in the production of synthesis gases

extracted from the natural gas.In the reformer, steam is mixed with the natural gas and the mixed stream is heated and routed through the tubes that contain nickel oxide catalyst. There will be such reaction caused by the methane from the natural gas which will be partially converted into:

Hydrogen Carbon dioxide Carbon monoxide.

The reactions that occur in the steam reformer are steam methane and water gas which can be summarized as follows:

CH4 + H2O CO + 3H2CO + H2O CO2 + H2

The figure below shows the outer and inner shape of the reformer (figure 1). The detailed design will be explained more through this report.

3

Figure 1. Steam reformer outer and inner shape

DesignThe design standard that is used for the reformer is API 530. The design of the steam reformer is:

o A rectangular insulated structure. o Vertical supported tubes. o Tubes are filled with nickel oxide catalyst in which the steam reforming

takes place at high temperatures. In the figure below, you can see the arrangement of a furnace with the reformer columns that has catalyst. The number of columns varies as it depends on the number and size of the walls. The number of catalyst tube is

4

672 that are manufactured with high alloy materials containing nickel and chrome.

Figure 2. Furnace with reformer columns

Design system of the reformero The design standard is API 530. o Designer should consider the allowable rupture strength to be close to

41 MPa for a life of 100,000 hours.o Rupture design is to prevent creep rupture, to design in creep range at

higher temperature, and to consider the allowable stress based on rupture strength.

o On the roof of the reformer, there are firing burners causing the endothermic heat reaction.

o Burners are arranged in rows between the reforming tubes. o Burners are placed in a manner as no flame impingement may occur on

the tube or on the furnace walls.

5

o A system of headers on the top of the reforming furnaces to distribute the natural gas and steam reactants.

o The catalyst tubes are high-chromium and nickel alloy that is 25Cr and 35Ni.

o Tubes are welded to the headers and pigtails which link the inlet of reagents and the exit of products to the main transfer line (Figure 3).

o The requested alloy is a modification of American Society of Testing Materials (ASTM).

o The design of the reformer furnace components takes into account the creep performance of the materials and is generally based on 10 years life or 100,000 hours.

Figure 3. Schematic of a pigtail connecting are former furnace tube to the main transfer line.

The main components of reformer: Burners:

o Main and auxiliary burners

6

Figure 3. Burners & Tubes Radiant coils:

o Catalyst tubeso Inlet and outlet manifoldso Inlet and outlet pigtails

Figure 4. Catalysts inside a reformer tube

Convection section coil Ducting

o Air ducting with supports and guides

7

o Turning Flue gas ducting with supportso Main burners ducto Transition ducto Air intakeo Flue gas duct to stack

Refractory radiant and auxiliary firing lining Steel works Piping

o Interconnection piping (convection to radiant)o Steam and mixed feed gaso Inlet manifoldso Inlet and outlet pigtailso Main and auxiliary burners piping completeo Instrumento Drain and vent connection.

Reformer gas main Process Flue gas stack (figure 5).

Figure 5. Flue gas stack

Equipmento Steam super-heater o Mixed feed heatero Combustion air preheatero Flue gas stack

8

o Flue gas fan with steam turbineo Combustion air fan with steam turbine.

Failure causes o Operating factors.o Design factors.o Changed in wall thickness.o Changed in Materials. o Sudden interruption in operation. o Rapid contraction and expansion of tubes. o Tube cracking. o Catalyst failure o Inaccurate temperature measurements.

Figure 6. Damaged Tubes with cracks

Inspection The main purposes of steam reformer inspection are:

o To confirm that the reformer is on the required efficiency. o To be on the safety standard. o To maximize the catalyst tubes extension o To draw the remaining life of the tubes.

9

The catalyst tubes are made from nickel and chrome; however, the price of nickel is very high as the cost of a single catalyst tube can be more than 75000 Saudi Riyals. Therefore, the unplanned downtime in reducing the plant on-stream factor is far greater than the installed cost of a single reformer tube. Inspection of the reformer is mostly for the tube catalyst and it is sometimes only possible to do that at shutdowns. The inspection technique generates accurate and repeatable results. The methods used in inspecting the reformer are as follows: Laser-Optic Tube Inspection System (LOTIS). Destructive Testing. Visual Inspection. Ultrasonic Attenuation (UT). Eddy Current (ET). Temperature measurement.

The details of each method are illustrated below which will show the difference between them: Laser-Optic Tube Inspection System (LOTIS)This method helps to determine the tube damage at very early stages and the time of a tube to be retired from the service. The internal inspection can be done during a turn around once the reformer catalyst is being changed. This process may take less than 3 minutes per tube. There is no necessity to access the reformer box; the only required access is from the top of the tubes where the catalysts are discharged.

10

Figure 7. LOTIS Probe & Helical Scan

Destructive Testing This is the most difficult method to do and it is very costly. This is because the catalyst tubes must be removed from the reformer and then cut up to allow for the amount of the creep damage to be determined. Visual InspectionThis is the very basic method as it is not enough to highlight operational problems. Thus, it will not determine the damage within the tube material as it depends on the familiarity of the inspecting eye. However, it is always useful to combine this method with other methods. Ultrasonic Attenuation (UT)This method transmits sound from the external part of the tube by a transmitter to a detector sensor. If there is a creep, then the signal will be attenuated and that will identify the damaged areas. This technique sometimes fails to identify the damaged areas since the surface of the tubes and material grain structures are both rough. Eddy Current (ET) This method is similar to ultrasonic attenuation (UT). It is applied outside the reformer tubes to determine the variations in flux density. The eddy current technique also has a less damage sensitivity especially at the inside surface of the tube wall. This test method may provide false positives and cause to replace a good conditioned tube and sometimes may provide false negatives which cause to keep the damaged tube.

11

Figure 8. Eddy Current

Temperature measurement This technique is used to measure temperature while the reformer is working. This is can be done by using a device called thermo graphic camera through the reformer window. The inspector should point this device to the catalyst tubes to measure the temperature (Figure 5). This device might give inaccurate measurement do to the uncontrollable variables:

o Background radiationo Emissivityo Flue gas composition

Therefore, the inspector must take this in account to get accurate measurements.

Figure 9. Thermo graphic camera for Temperature measurement

12

Reformer Revamp

o Revamp means renovating the steam reformer to have it for 100,000 hrs.

o It is based on the API 530.o Replacing the catalysts. o Replacing the catalyst tube.o Burners are not included in the revamp unless they are damaged.

Reformer start up

o Confirmation for startup. o Substitution for Reformed Gas (RG), Processed Natural Gas (PNG), Fuel

Purge gas (FPG), Fuel Natural Gas (FNG).o Start-up 1.D. Fan.o Igniting the arch burners to reheat the catalysts.o Switching over carrier gas to process steam.o Pressurizing the system.

Reformer Shutdown

o Shutting down the Fuel Purge Gas (FPG) burners.o Shutting down the Gas Compression section. o Reducing the pressure of the Reformed Gas (RG) line. o Stopping the Purge Natural Gas that goes to reformer.o Isolating the Waste Heat Boiler system from steam header.o Reducing the pressure of the system.o Switching the over carrier gas to plant air.o Cooling down reformer furnace and at the end stopping water

circulation.

Plans and report Conclusion

In this report, I showed what I learned about the reformer in terms of design, and all types

of inspection. In conclusion, I am ending my summer training here in AR-RAZI. I had a

good opportunity for this summer to enhance my knowledge and to gain experience in

my field in mechanical engineering. For that reason, I always like to express my thanks

13

and appreciations to all employees who helped me and taught me to improve my

knowledge in this subject. This report presented what I learned in the site about steam

reformer in terms of definition, design, failures, inspection, revamp, start up, and shutdown of the reformer.

14