0 Preface
The hydrogenation device was first developed by Germany in the early 20th century. At that time, Germany lacked oil resources and was compensated by hydrogenation of coal tar. After the end of the Second World War, the hydrogenation process was greatly developed in the processing of crude oil. Hydrogenation units became the main devices in refineries around the world.
Since China is a country with relatively little energy, crude oil imports a lot and coal is relatively large. In recent years, the comprehensive utilization of coal chemical oil and residue oil has been vigorously carried out. Provide catalytic hydrogenation to produce qualified fuel oil or chemical feedstock oil. At the beginning of 2013, the company handed over the design of self-control of a private oleo-hydrogenation plant project in Shandong to self-control design.
1 Process requirements
The technical difficulty of hydrogenation equipment lies in the measurement and control of high temperature and high pressure media. Including temperature, pressure, flow, level measurement; and flow control of high temperature and high pressure media.
High-temperature and high-pressure medium is mainly divided into gas and liquid: gas is mainly hydrogen, divided into new hydrogen and recycled hydrogen; liquid is mainly raw oil and process oil, and some of the sulfur-containing sewage.
2 High pressure regulator valve selection
According to different technological requirements, high-pressure control valves are divided into single seat control valves and single seat angle valves, as shown in Fig. 1 and Fig. 2 .
Figure 1 High pressure single seat regulator
Figure 2 high pressure single seat angle valve
According to the process requirements, for high pressure flow control valves, high pressure angle valves are required when the pressure difference between the front and rear of the valve is large.
2.1 Selection of Valve Body Material
According to the design specification, the body material must be equal to or better than the material of the process pipe.
Due to the characteristics of hydrogen, in the hydrogenation process, there are special requirements for high-pressure hydrogen pipeline materials, and A106 carbon steel is generally used. The hydrogen control valve must be made of hydrogen-brittle material (hydrogen brittleness occurs when the temperature of the hydrogen medium reaches a certain height), so the special carbon steel A216WCC is used. Hydrogen is divided into new hydrogen and recycled hydrogen. For the components that will contain sulfur in circulating hydrogen, the material selection must be added (sulfur resistant type).
For liquid media, especially raw oils and intermediate media, because it is a product of crude oil processing, it has high viscosity and contains more heavy components. When the temperature is low, the viscosity is higher and it is easy to condense. Operating temperature is 180 degrees to 270 degrees Celsius. The higher requirements are placed on the regulating valve. Therefore, special carbon steel A216WCC or stainless steel A351CF8C is selected. For a partially reacted, sulfur-containing medium, material selection must be added (sulfur resistant). Carbon steel material has NACE processing requirements.
Figure 3 high pressure angle valve, one with a prepared
Figure 4 M2 body structure
2.2 Selection of valve core material and valve seat material
According to the requirements of material strength, most of the control valves use 316L stainless steel, and some of the high-temperature media use 347 (cracked feedstock oil, refined feedstock oil, cracked mixed hydrogen oil, refined heat high oil, cracked heat high oil).
2.3 Selection of packing
For low temperature media, DoublePTFE PTFE is used; for high temperature media, Single Graphite graphite is used.
2.4 Traffic Characteristics
For high pressure single seat regulators, the flow characteristics are commonly used as equal percentages; for high pressure angle valves, the flow characteristics should be linear (available from the valve manufacturer).
This project adopts Germany imported control valve. The flow characteristics of high pressure single seat control valve and high pressure angle valve are equal percentage.
2.5 Selection of High Pressure Angle Valve Flow Direction
Due to the use of high pressure angle valves, care must be taken to the flow of the medium. Most manufacturers of high-pressure angle valves recommend bottom-in side-out; according to the characteristics of the high-pressure angle valve, it is generally required that the liquid medium enters the bottom and the gas medium enters the bottom. For the liquid medium, when the bottom side is out, the cavitation is large, and Stellite welding and other welding processes must be added to strengthen the valve body. (The side-in bottom-out process considers the high velocity on the low-pressure side and the high-speed fluid damages the equipment. ).
In this project, there are 4 outlet valves for hot high-divided tanks. After the calculation by the manufacturers, the vaporization rate is high and the diameter of the outlet must be enlarged. Therefore, the 2†inlet and 3†outlets are used, and the structure is the side inlet and bottom outlet.
2.6 Selection of Hand Wheels
Due to the high process requirements of the use of high-pressure control valves, handwheels must be equipped, mainly based on pneumatic actuators, mostly installed on the top of the regulating valve, and a small amount installed on the side of the regulating valve. Mounted on the top can be rotated directly, and a gear transmission mechanism is required to be installed on the side, which has reliability concerns in the field.
3 high pressure shut-off valve selection
High pressure shut-off valve uses parallel gate valve.
3.1 Application of high pressure shut-off valve
It is used for raw material oil feeding, high-point tank export, emergency venting and high-pressure water injection. Therefore, it requires quick action and adopts pneumatic double acting actuator without feedback spring. The supporting solenoid valve adopts the original ASCO two-position three-way flameproof type, providing a locking valve, and a two-position five-way and two two-position three-way pneumatic actuators to push the cylinder. In order to ensure the fault condition, the valve is in a safe position, and the gas tank is specially added to ensure that the valve can be returned to a safe position at least twice. Due to the large diameter of the valve, the torque of the actuator is required to be higher. Therefore, the manufacturer requires a 3/4†air source connector.
3.2 Selection of Valve Body Material
Body material selection A216-WCB, sulfur-containing medium required anti-H2S; hot high points export selection A351-CF8C (do NACE certification).
3.3 Selection of valve core material and valve seat material
Spool material and valve seat material are made of SUS304 stainless steel, which is made of SAS 316 stainless steel, and SUS347 stainless steel is used for hot HC export.
3.4 Selection of packing
Filler is selected according to the medium temperature. Graphite is used for this project.
3.5 Selection of Handwheels
According to the process requirements matching handwheel.
4 High-voltage electric shut-off valve selection
High-pressure electric shut-off valves use Y-type globe valves.
Figure 5 M2 Body: Standard
Figure 6 High pressure shut-off valve control air supply
4.1 Application of High-voltage Electric Shut-off Valve
Used for export control of new hydrogen compressors and recycle hydrogen compressors.
4.2 Selection of Valve Body Material
Body material selection A216-WCB, circulating hydrogen need anti-H2S.
4.3 Selection of packing
Filler is selected according to the medium temperature. Graphite is used for this project.
4.4 Selection of Handwheels
All need to bring a hand wheel.
4.5 Electric Actuator
Adopted domestic joint venture products. Due to the requirement of the speed of operation, it is necessary to cooperate with a power-intensive electric actuator. The power supply uses a three-phase 380V power supply. Pay special attention to the need to ensure the power supply in the design (motor starting power is very high).
Since the pressure rating is CLASS1500 or CLASS2500, the flange type uses RJ sealing face.
Figure 7 Control valve of the shut-off valve
Figure 8 Gas tank
Figure 9 Cross-section of a Y-type globe valve
Special attention: The ring connection surface needs to use a metal ring pad, and the hardness of the metal material must be lower than the flange material 30. Due to the special requirements of hydrogenation, many of the process piping are made of carbon steel materials and have low hardness. Therefore, it is recommended that the materials of the metal ring gaskets be made of soft iron materials.
5 Issues to Consider in Design
Due to the particularity of hydrogenation equipment, involving high temperature and high pressure media, and the complexity of raw material oil, the viscosity is usually high, which puts higher requirements on the control valve; while high pressure hydrogen is needed to prevent hydrogen embrittlement of the material; And the intermediate process oil contains sulfur and hydrogen sulfide components, and the material needs to have sulfur resistance properties.
For the high-pressure control valve, its external dimensions and quality are much larger than the low-pressure control valve, so it is necessary to carefully check after the manufacturer returns the ordering information, and cooperate with the piping professional to reasonably arrange the installation position.
Figure 10 High pressure flange sealing surface
Figure 11 Ring connection surface
6 Conclusion
The application of the oleo-hydrogenation unit converts the low-value oysteroil into light naphtha and diesel oil. The diesel product of this device can be used as fuel for vehicles. Its sulfur content and nitrogen content are in line with the National V Standard. Greatly improved the value of the product and produced very good results.
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