USH1416H - Method for extending the life of a curved section in a pipe for the transport of finely divided fluidized particulate solids - Google Patents
Method for extending the life of a curved section in a pipe for the transport of finely divided fluidized particulate solids Download PDFInfo
- Publication number
- USH1416H USH1416H US08/265,906 US26590694A USH1416H US H1416 H USH1416 H US H1416H US 26590694 A US26590694 A US 26590694A US H1416 H USH1416 H US H1416H
- Authority
- US
- United States
- Prior art keywords
- finely divided
- particulate solids
- pipe
- curved section
- life
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000007787 solid Substances 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims abstract description 10
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000009792 diffusion process Methods 0.000 claims abstract description 14
- 229910052796 boron Inorganic materials 0.000 claims abstract description 13
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 6
- 239000010959 steel Substances 0.000 claims abstract description 6
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 5
- 239000003054 catalyst Substances 0.000 claims description 8
- 238000004523 catalytic cracking Methods 0.000 claims description 6
- 229910001347 Stellite Inorganic materials 0.000 description 8
- AHICWQREWHDHHF-UHFFFAOYSA-N chromium;cobalt;iron;manganese;methane;molybdenum;nickel;silicon;tungsten Chemical compound C.[Si].[Cr].[Mn].[Fe].[Co].[Ni].[Mo].[W] AHICWQREWHDHHF-UHFFFAOYSA-N 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 229910000975 Carbon steel Inorganic materials 0.000 description 6
- 239000010962 carbon steel Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000004231 fluid catalytic cracking Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000005552 hardfacing Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G53/00—Conveying materials in bulk through troughs, pipes or tubes by floating the materials or by flow of gas, liquid or foam
- B65G53/34—Details
- B65G53/52—Adaptations of pipes or tubes
- B65G53/523—Wear protection
Definitions
- This invention relates to the use of pipes for the transportation of fluidized finely divided particulate solids and more particularly to an improvement in such methods whereby the service life of the pipes may be extended.
- fluidized particulate solids such as fluid catalytic cracking catalyst particles are transported as a fluidized stream of particulate solids.
- Such fluidized finely divided particulate solids are extremely damaging to the pipes in which they are transported, particularly at curved surfaces such as elbows and the like. It is not uncommon to find that the life of elbows in pipes used for such applications may be as little as three to four months.
- the outer radius of the elbow fails as a result of the gouging erosion resulting from the flow of the fluidized finely divided particulate solids through the pipe and around the elbow.
- the pre-rotation vanes are frequently fabricated of carbon steel such as carbon or low alloy steel such as steel containing about 2.25% chrome and about 0.5% molybdenum. Other materials can be used but steel is a frequent material of construction for the pre-rotation vanes. Unfortunately, the steel vanes can be rapidly eroded and degraded by impact with the fluidized finely divided particulate solids so that the pre-rotation vanes themselves begin to be quickly eroded and their effectiveness reduced. To overcome this shortcoming, harder materials have been overlaid on the steel vanes to protect the pre-rotation vanes in such applications. STELLITE (trademark of Stoody Deloro Stellite, Inc. for metal alloys) alloy is one material which has been frequently used as a hard facing overlay.
- the STELLITE alloy is generally welded onto the carbon steel pre-rotation vanes to produce the final prerotation vanes for inclusion in the pipe.
- STELLITE alloy has a Rockwell C hardness of about 70 to 75 which is roughly the same as the Rockwell C hardness of the catalytic cracking catalyst solids.
- the STELLITE alloy when welded onto the pre-rotation vanes, results in thicker vanes to the detriment of flow through the pipe. Further, fluidized finely divided fluid catalytic cracking catalyst is frequently transported at temperatures approximating 1300° F. which is outside the upper range generally considered suitable for STELLITE alloy.
- an improvement is provided in a method for extending the life of a curved section in a pipe wherein finely divided particulate solids are transported in fluidized flow by positioning pre-rotation vanes upstream of the curved section, the improvement comprising the use of pre-rotation vanes fabricated of carbon steel and hardened by boron vapor diffusion hardening.
- pre-rotation vanes positioned upstream from a curved section in a pipe used for the transportation of fluidized finely divided solids are hardened by a boron gas diffusion process described in a publication by VaporKote, Inc. entitled “Boron Gas Diffusion Coating” published May 27, 1987.
- the boron vapor diffusion hardening process is considered to be well known to those skilled in the art and generally consists of packing the part to be treated in boron powder, placing the part packed in the boron powder in an oven at approximately 1800° F. where the boron powder vaporizes and, as vaporized, diffuses into the metal, thereby hardening all surfaces of the metal.
- the resulting boron vapor diffusion hardened pre-rotation vanes are smoother than can be readily produced using STELLITE alloy overlays and have a Rockwell C hardness of about 80 to about 85.
- the outer surface of the boron vapor diffusion hardened pre-rotation vanes is now harder than the fluidized catalytic cracking catalyst particles.
- pre-rotation vanes are not thickened and do not impede flow to any greater extent than the carbon steel pre-rotation vanes initially passed to the boron vapor diffusion hardening treatment.
- the design and fabrication of the pre-rotation vanes is considered to be well known to those skilled in the art and will not be discussed further except to note that no adjustment in the vane thickness is necessary to allow for the added thickness as required with the STELLITE alloy hard surfacing normally used in such applications.
- the pre-rotation vanes can be designed of carbon steel at the desired size and then passed to boron vapor diffusion hardening which achieves the desired hardening with no change in pre-rotation vane dimensions.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
Abstract
A method for extending the life of a curved section in a pipe wherein finely divided particulate solids are transported in fluidized flow by positioning pre-rotation vanes upstream of the curved section, the improvement comprising the use of pre-rotation vanes fabricated of steel and hardened by boron vapor diffusion hardening.
Description
1. Field of the Invention
This invention relates to the use of pipes for the transportation of fluidized finely divided particulate solids and more particularly to an improvement in such methods whereby the service life of the pipes may be extended.
2. Background Art
In numerous industrial applications such as fluidized catalytic cracking operations, finely divided fluidized particulate solids such as fluid catalytic cracking catalyst particles are transported as a fluidized stream of particulate solids. Such fluidized finely divided particulate solids are extremely damaging to the pipes in which they are transported, particularly at curved surfaces such as elbows and the like. It is not uncommon to find that the life of elbows in pipes used for such applications may be as little as three to four months. Typically, the outer radius of the elbow fails as a result of the gouging erosion resulting from the flow of the fluidized finely divided particulate solids through the pipe and around the elbow. Since such processes are frequently operated and a high degree of reliability is desired, the requirement to shut down the process and replace elbows at this frequency is very disadvantageous. It has been found that fluidized finely divided particulate solids can be transported through such pipes and the life of the curved sections of the pipe, such as elbows, extended by the use of pre-rotation vanes such as Cheng Rotation Vanes marketed by Cheng Fluid Systems, Inc. Cheng Rotation Vanes comprise a set of pre-rotation vanes installed upstream of a pipe elbow to alter the characteristics of the incoming flow to the elbow to compensate for the turning effects of the particular elbow geometry. These pre-rotation vanes have been effective to extend the life of elbows positioned in pipes used for the transportation of fluidized finely divided particulate solids. Such vanes are considered to be known to those skilled in the art and are described in a technical bulletin issued by Cheng Fluid Systems, Inc., Volume 1, No. 2, Sep. 1990.
The pre-rotation vanes are frequently fabricated of carbon steel such as carbon or low alloy steel such as steel containing about 2.25% chrome and about 0.5% molybdenum. Other materials can be used but steel is a frequent material of construction for the pre-rotation vanes. Unfortunately, the steel vanes can be rapidly eroded and degraded by impact with the fluidized finely divided particulate solids so that the pre-rotation vanes themselves begin to be quickly eroded and their effectiveness reduced. To overcome this shortcoming, harder materials have been overlaid on the steel vanes to protect the pre-rotation vanes in such applications. STELLITE (trademark of Stoody Deloro Stellite, Inc. for metal alloys) alloy is one material which has been frequently used as a hard facing overlay. The STELLITE alloy is generally welded onto the carbon steel pre-rotation vanes to produce the final prerotation vanes for inclusion in the pipe. Unfortunately, STELLITE alloy has a Rockwell C hardness of about 70 to 75 which is roughly the same as the Rockwell C hardness of the catalytic cracking catalyst solids. Further, the STELLITE alloy, when welded onto the pre-rotation vanes, results in thicker vanes to the detriment of flow through the pipe. Further, fluidized finely divided fluid catalytic cracking catalyst is frequently transported at temperatures approximating 1300° F. which is outside the upper range generally considered suitable for STELLITE alloy.
Accordingly, an improved method for extending the life of pre-rotation vanes used in pipes and the life of pipes used for the transportation of fluidized catalytic cracking catalyst solids has been sought.
According to the present invention, an improvement is provided in a method for extending the life of a curved section in a pipe wherein finely divided particulate solids are transported in fluidized flow by positioning pre-rotation vanes upstream of the curved section, the improvement comprising the use of pre-rotation vanes fabricated of carbon steel and hardened by boron vapor diffusion hardening.
According to the present invention, pre-rotation vanes positioned upstream from a curved section in a pipe used for the transportation of fluidized finely divided solids are hardened by a boron gas diffusion process described in a publication by VaporKote, Inc. entitled "Boron Gas Diffusion Coating" published May 27, 1987. The boron vapor diffusion hardening process is considered to be well known to those skilled in the art and generally consists of packing the part to be treated in boron powder, placing the part packed in the boron powder in an oven at approximately 1800° F. where the boron powder vaporizes and, as vaporized, diffuses into the metal, thereby hardening all surfaces of the metal. The resulting boron vapor diffusion hardened pre-rotation vanes are smoother than can be readily produced using STELLITE alloy overlays and have a Rockwell C hardness of about 80 to about 85. The outer surface of the boron vapor diffusion hardened pre-rotation vanes is now harder than the fluidized catalytic cracking catalyst particles.
Further, the pre-rotation vanes are not thickened and do not impede flow to any greater extent than the carbon steel pre-rotation vanes initially passed to the boron vapor diffusion hardening treatment.
Use of these boron vapor diffusion hardened prerotation vanes in pipes used for the transportation of fluidized finely divided fluid catalytic cracking catalyst solids has resulted in greatly extended life for the pipe elbows positioned downstream from the boron vapor diffusion hardened pre-rotation vanes.
The use of boron vapor diffusion hardening is considered to be well known to those skilled in the art and will not be discussed in detail.
Similarly, the design and fabrication of the pre-rotation vanes is considered to be well known to those skilled in the art and will not be discussed further except to note that no adjustment in the vane thickness is necessary to allow for the added thickness as required with the STELLITE alloy hard surfacing normally used in such applications. In other words, the pre-rotation vanes can be designed of carbon steel at the desired size and then passed to boron vapor diffusion hardening which achieves the desired hardening with no change in pre-rotation vane dimensions.
Having thus described the invention by reference to certain of its preferred embodiments, it is respectfully pointed out that such embodiments are illustrative rather than limiting in nature and that many variations and modifications are possible within the scope of the present invention. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon the foregoing description of preferred embodiments.
Claims (4)
1. In a method for extending the life of a curved section in a pipe wherein finely divided particulate solids are transported in fluidized flow by positioning pre-rotation vanes upstream of said curved section, the improvement comprising the use of pre-rotation vanes fabricated of steel and hardened by boron vapor diffusion hardening.
2. The improvement of claim 1 wherein said particulate solids are finely divided particulate fluidized catalytic cracking catalyst having a Rockwell C hardness from about 70 to about 75.
3. The method of claim 1 wherein said boron vapor diffusion hardened pre-rotation vanes have a Rockwell C hardness from about 80 to about 85.
4. The improvement of claim 1 wherein said finely divided particulate solids are finely divided particulate fluidized catalytic cracking catalyst solids and wherein said finely divided particulate solids are transported in said pipe at a temperature of about 1300° F.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/265,906 USH1416H (en) | 1994-06-27 | 1994-06-27 | Method for extending the life of a curved section in a pipe for the transport of finely divided fluidized particulate solids |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/265,906 USH1416H (en) | 1994-06-27 | 1994-06-27 | Method for extending the life of a curved section in a pipe for the transport of finely divided fluidized particulate solids |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USH1416H true USH1416H (en) | 1995-02-07 |
Family
ID=23012362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US08/265,906 Abandoned USH1416H (en) | 1994-06-27 | 1994-06-27 | Method for extending the life of a curved section in a pipe for the transport of finely divided fluidized particulate solids |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USH1416H (en) |
-
1994
- 1994-06-27 US US08/265,906 patent/USH1416H/en not_active Abandoned
Non-Patent Citations (12)
| Title |
|---|
| Chemical Engineering, Sep. 1992, "New In-Pipe Flow Conditioner Cuts Fluid Problems". |
| Chemical Engineering, Sep. 1992, New In Pipe Flow Conditioner Cuts Fluid Problems . * |
| Cheng Fluid Systems, Inc. Technical Bulletin, Sep. 1990 "Cheng Rotation Vanes (CRV)". |
| Cheng Fluid Systems, Inc. Technical Bulletin, Sep. 1990 Cheng Rotation Vanes (CRV) . * |
| Cheng Fluid Systems, Inc., Letter to Jon Berge, Aug. 6, 1992. * |
| Cheng Fluid Systems, Inc., letter to Meir Snir, Oct. 24, 1991. * |
| Machine Design, Aug. 23, 1990, "Rotational Vane Smooths Out Fluid Flow". |
| Machine Design, Aug. 23, 1990, Rotational Vane Smooths Out Fluid Flow . * |
| Turbine Metal Technology, Inc., "A Better Diffusion Coating for Centrifugal Pumps" date unknown but available to inventor as reference). |
| Turbine Metal Technology, Inc., A Better Diffusion Coating for Centrifugal Pumps date unknown but available to inventor as reference). * |
| VaporKote, Inc., May 27, 1987, "Boron Gas Diffusion Coatings". |
| VaporKote, Inc., May 27, 1987, Boron Gas Diffusion Coatings . * |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| STCF | Information on status: patent grant |
Free format text: PATENTED CASE |