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Vee Wire Scallop

JOHNSON SCREEN

Vee Wire Scallop

Radial Flow Reactor Internals: Vee Wire Scallop | Johnson Type Centerpipes
VEE-WIRE SCALLOP – JOHNSON SCREEN SCALLOP – WEDGE WIRE SCREEN SCALLOP
(more convenient installation and maintenance) (for gas solid radial reactor)

The existing gas-solid radial reactor is equipped with a gas distribution device and a gas gathering device, which are respectively installed in the center and around the reactor. The gap between the two is filled with catalyst to form a catalyst bed.
The flat tube like equipment distributed uniformly along the vessel wall is called scallop tube. According to the different flow directions of the gas, they act as the flow diversion channel or the flow collection channel of the gas respectively.

Our company can produce various sizes of Vee-Wire Scallops (Johnson screen scallops). It has the characteristics of high strength, excellent surface finish, high precision, smooth and flat girth weld.
Wedge wire screen laser processing, precise gap, neat spacing and even distribution.
Advanced measuring instruments are used in the production process to ensure good straightness and product quality of the Johnson screen scallops cylinder.

It is widely used in catalytic reforming, ammonia synthesis and other process units.

Material: Stainless steel 304, 316, 316L.
Profile wire: 0.76×1.5mm, 1.5×2.5mm, 2.0×3.0mm, 2.0×4.0mm, 2.5×3.0mm, 3.0×5.0mm, 3.0×6.0mm or as your need.
Support rod: 2.0×3.0mm, 3.0×5.0mm, 5.0×8.0 or as your need.

Slot size (gap size): 0.3mm or as your need (meet the requirements of small catalyst retention).
Welding mode: Circular fusion welding, resistance welding.
Equipment (for screen scallops): Wedge wire drawing equipment, wedge wire screen production equipment, laser cutting equipment, plasma welding equipment, etc.

Notes after purchasing wedge wire scallops

  1. Is the size accurate.
  2. Whether the screen surface is smooth.
  3. Whether the gap size is uniform.
  4. Whether the weld is strong.
  5. Pay attention to the correct installation steps.

Johnson Screen Scallops Vs Perforated Metal Screen Scallops

Advantage of Johnson screen type scallops:

  1. The ability to resist bending, buckling, twisting, or collapse.
  2. Low pressure, high efficiency.
  3. Self supporting structure, high strength.
  4. Continuous slotting structure, large opening area.
  5. Special v-wire structure, not easy to block, easy to clean.

Due to the high opening rate and large amount of punching, the sector plate is generally made of 1.2 or 1.5mm sheet steel, which is limited by the punching process.

The only advantage of perforated metal screen is its low price, but in practice, the performance of Johnson screen scallops is better, so it is recommended to use it.
In the typical configuration of radial flow reactor, the reaction gas flows radially on the catalytic bed through the slot of the wedge wire screen scallop tube around the reactor wall.

After passing through the catalytic bed, the gas will gather in the central tube and transfer to the next reaction stage.

In addition, in some applications, the gas flows in the same direction, that is, the gas flows from the inside out, but the basic structure of the internals is the same.
In practical industrial application (such as catalytic reforming reaction), the change of working state and temperature makes the catalyst bed change.

Especially in case of sudden shutdown, the catalyst moves towards the sector tube driven by the accumulated gas in the reactor, and the sector tube bears the external force, which is similar to the instability and deformation of the long cylinder under external pressure.

Our Johnson screen Scallops can solve the above problems and provide efficient services.