WO2007044818A1

WO2007044818A1 - Catalyst test unit

Info

Publication number: WO2007044818A1
Application number: PCT/US2006/039759
Authority: WO
Inventors: David J. Edwards
Original assignee: Univar Usa Inc.
Priority date: 2005-10-11
Filing date: 2006-10-11
Publication date: 2007-04-19

Abstract

A catalyst test unit (20) for use in simultaneously exposing a plurality of catalyst samples to contaminants in a fluid stream. The catalyst test unit (20) includes an inlet isolation valve (26) for controlling the flow of the fluid stream into the catalyst test unit and an inlet manifold (24) receiving the fluid steam, said inlet manifold separating into a plurality of individual branches such that each branch receives a portion of the fluid stream. A knock out vessel (32) is configured to remove water droplets from the fluid stream passing through the inlet manifold (24) and a total flow meter (28) configured to measure flow rate of the fluid stream in the inlet manifold. Catalyst-containing reactor vessels (38A-F) are connected to the individual branches such that the portion of the fluid stream in each branch is exposed to the catalyst in its respective reactor vessel. First and second outlet manifolds (50, 52) are fluidically connected to outlets of the reactor vessels and have first and second outlet isolation valves (56A-F, 58A-F) for each of the plurality of reactor vessels (38A-F) . The first and second outlet isolation valves (56A-F, 58A-F) can be positioned so that the portion of the fluid stream passing through each reactor vessel can be directed to either the first or second outlet manifold (50, 52) . An individual flow meter (54) is configured to measure the flow rate of a fluid stream in the second outlet manifold. The catalyst test unit further includes a protective frame (70) .

Description

CATALYST TEST UNIT

Reference to Related Application

[0001] The present application claims priority under 35 U.S. C. §119(e) to U.S.

Provisional Patent Application No. 60/725,199, filed October 11, 2005.

BACKGROUND OF THE INVENTION Field of Invention

[0002] This invention relates generally to the testing and evaluation of catalyst materials and, more particularly, to a testing unit for simultaneously evaluating a plurality of catalysts.

Description of Related Art

[0003] When formulating new catalysts, a large number of candidate catalyst compositions are typically synthesized. It then becomes important to evaluate the various candidate catalysts to determine and identify those formulations that are the most successful under actual conditions in the field. It is particularly advantageous to evaluate or compare the performance of various catalyst materials based on identical testing conditions. For example, it is desirable to remove hydrogen sulfide (H₂S) from natural gas with a catalyst. If H₂S is not removed to less than about 4 ppmv, it will combine with moisture in the gas to form a corrosive medium, which will corrode underground pipelines and shorten their service life. Additionally, H₂S above a few parts per million is very hazardous and can cause death or serious injury if inhaled. However, the effectiveness of specific catalysts depends upon the particular make-up of the natural gas at a particular site. Therefore, it would be advantageous to determine which catalysts are most effective under the conditions present at the particular site before choosing which catalysts to use.

[0004] Traditionally, the performances of various different catalysts have been evaluated using a sequential approach. In such an approach, each catalyst sample or candidate is typically independently serially tested in a selected reactor vessel at one or more sets of specified reaction conditions. After completion of the tests at one or more sets of conditions, the tested catalyst sample is typically removed from the test reactor vessel and the next catalyst sample is loaded into the reactor vessel. The testing is then repeated on the freshly loaded catalyst sample. The process is repeated sequentially for each of the desired catalyst formulations. As will be appreciated, the application of such a process to the testing of numerous various catalyst formulations can be undesirably time-consuming. [0005] The determination of true catalyst absorbent capacity (i.e., contaminant loading) is necessary for accurate catalyst bed performance predictions. However, it is often difficult to duplicate field conditions in a lab setting, and in certain situations, the catalyst being tested needs to be tested in actual field gas and/or liquid conditions to establish working contaminant absorbent capacities. For example, the volume of gas or liquid required for field slip stream tests are high enough that it would be difficult to provide and manage the large flowrates over the four to six month time required to conduct the test in the lab. For example, one particular test requires between about 166,000 - 250,000 standard cubic feet of 100 parts per million H₂S laden natural gas. This type of testing is best facilitated in the field at the plant location.

[0006] In view thereof, there is a need and a demand for procedural developments in catalyst evaluation to better ensure consistent data sets by permitting or facilitating evaluation or comparison of each of multiple catalyst samples under uniform test conditions in the field at the plant location.

SUMMARY OF THE INVENTION [0007] In one aspect, the invention is directed to a catalyst test unit for use in simultaneously exposing a plurality of catalyst samples to contaminants in a fluid stream. The catalyst test unit includes an inlet isolation valve for controlling the flow of the fluid stream into the catalyst test unit and an inlet manifold receiving the fluid steam, the inlet manifold separating into a plurality of individual branches such that each branch receives a portion of the fluid stream. The catalyst test unit also includes a knock out vessel configured to remove water droplets from the fluid stream passing through the inlet manifold and a total flow meter configured to measure the flow rate of the fluid stream in the inlet manifold. The catalyst test unit also includes a plurality of catalyst-containing reactor vessels, wherein each of the plurality of individual branches is fluidically connected with one of the reactor vessels such that the portion of the fluid stream in each branch is exposed to the catalyst in its respective reactor vessel. The catalyst test unit also includes first and second outlet manifolds fluidically connected to outlets of the reactor vessels and first and second outlet isolation valves for each of the reactor vessels. The first and second outlet isolation valves can be positioned so that the portion of the fluid stream passing through each reactor vessel can be directed to either the first or second outlet manifold. The catalyst test unit also includes an individual flow meter configured to measure the flow rate of a fluid stream in the second outlet manifold. In one embodiment, the catalyst test unit further includes a protective frame.

[0008] These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above mentioned and other features of this invention will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0010] FIGURE 1 is a perspective view of a catalyst test unit according to the invention;

[0011 ] FIGURE 2 is a side view of the catalyst test unit of FIG. 1 ;

[0012] FIGURE 3 is a plan view of the catalyst test unit of FIG. 1 ;

[0013] FIGURE 4 is an end view of the catalyst test unit of FIG. 1 ;

[0014] FIGURE 5 is a schematic representation of the catalyst test unit of FIG. 1;

[0015] FIGURE 6 is another schematic representation of the catalyst test unit of FIG.

1;

[0016] FIGURE 7 is a side view of a threaded rod and piston assembly for use in removing the catalyst from a reactor vessel of the catalyst test unit; and

[0017] FIGURE 8 is another view of the threaded rod and piston assembly configured for catalyst removal.

[0018] Corresponding reference characters indicate corresponding parts throughout the views of the drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0019] The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description.

[0020] Turning now to FIGS. 1-4, there is illustrated a catalyst test unit, generally designated with the reference numeral 20, in accordance with one embodiment of the invention. The catalyst test unit 20 simultaneously exposes a plurality of catalyst samples to contaminants in a fluid stream so that the absorbent capacity (i.e., contaminant loading) of the multiple catalyst samples can be measured under uniform test conditions. As shown, a fluid feed stream is attached to an inlet 22 of the catalyst test unit 20 and feeds into an inlet manifold 24. The fluid feed is preferably gaseous, and in the described embodiment, the catalyst test unit 20 is used to test catalysts used in natural gas systems. However, it is to be understood that the catalyst test unit 20 may be used to test catalysts for use in other environments. Additionally, the catalyst test unit 20 is desirably portable so that it may be used in the field such that it may be placed in the natural gas piping at a natural gas facility. A main inlet metering valve 26 controls the total flow rate of the natural gas into the catalyst test unit 20. Those skilled in the art and guided by the teachings herein provided will appreciate that the fluid flow rate can be adjusted on a mass basis (e.g., mass flow rate) or a volumetric basis (e.g., volume flow rate), as may be desired in particular applications. A total flow meter 28 positioned in the inlet manifold 24 near the main inlet metering valve 26 measures the total flow rate of the natural gas through the inlet manifold 24. An inlet flow pressure gage 30 measures the pressure in the inlet manifold 24.

[0021] The inlet manifold 24 also contains a knock out vessel 32 designed to catch and remove liquid slugs, such as water droplets, that may be present in the natural gas stream. Water droplets, if not removed, are absorbed by the catalysts and may cause the catalysts to become fouled and soaked. Water soaking of the catalysts to be tested may render them inactive with respect to contaminant absorption and lead to inaccurate test results. In one embodiment, the knock out vessel 32 is a chamber that provides an enlarged volume through which the feed of natural gas flows. The enlarged volume of the knock out vessel 32 creates a decreased pressure condition as the natural gas feed flows through the vessel thereby causing the water droplets to fall out and collect at the bottom of the vessel. A liquid drain valve 34 is provided near the bottom of the knock out vessel 32 so that water collected in the vessel may be periodically drained. One example of a knock out vessel 32 is described, however those skilled in the art will appreciate that other mechanisms may be used to remove water slugs from the fluid stream [0022] Downstream from the knock out vessel 32, the inlet manifold 24 separates into a number of individual branches 36. In the illustrated embodiment, six separate branches 36 are employed, individually designated 36A-F, respectively, so as to form six corresponding individual feed streams. Each branch 36A-F has an associated reactor vessel 38A-F into which the individual feed stream is introduced. Desirably, the reactor vessels 38 A-F are arranged in a parallel array as illustrated. The array of parallel reactor vessels 38 A-F is formed so that catalysts within the reactor vessels can be tested simultaneously under uniform conditions. In the illustrated embodiment, the catalyst test unit 20 contains six reactor vessels 38 A-F. However, other numbers of reactor vessels 38 A-F may be used, including but not limited to 2, 4 or 8 reactor vessels, without departing from the scope of the invention. It is generally preferred that the array of parallel reactor vessels 38 A-F be arranged in a row and column formation.

[0023] The six branches 36A-F are each conducted through a respective individual metering valve 40A-F to regulate or control the flow rate of the six corresponding individual reactor feed streams. Depending upon the application and the data desired or variables being investigated, the set of feed streams may be regulated or controlled to provide the same feed fluid flow to the reactor vessels 38 A-F or they may be controlled at different flow rates. [0024] The reactor vessels 38 A-F each house or contain a measured amount of at least one of a plurality of catalyst samples. As identified below, each of the reactor vessels 38 A-F may contain a catalyst sample composed of different catalyst materials, different mixtures of catalyst materials, or, alternatively, the same compositional mixture of catalyst materials but where the components are in different ratios, or the like. Furthermore, identical catalyst sample formulations or mixtures may be repeated within the array of the parallel reactor vessels 38 A-F, especially such as when statistical analysis is being conducted. Each reactor vessel 38 A-F contains a measured amount of at least one of the plurality of catalyst samples to be tested. The catalyst test unit 20 is desirably used with catalysts that have varying combinations of iron oxide compounds. Iron oxide catalysts are used to remove hydrogen sulfide (H₂S) from natural gas. These different catalysts to be tested also have varying levels of porosity and internal surface area. The internal chemical compound matrix of each catalyst may also be varied to some degree. The catalyst test unit 20 can also be used to remove some if not all of the more complex sulfurs, mercaptans, COS, DMS, etc. by using sulfur absorbent catalysts manufactured using varying combination of metal oxides and metal carbonates, acetates, etc. The following is a general list of potential catalyst that could be tested in the catalyst test unit 20 for absorbing or scavenging sulfur compounds: zinc oxide, zinc oxide/copper oxide, zinc oxide/copper oxide/alumina oxide, copper oxide/alumina oxide, zinc carbonate/copper carbonate, copper carbonate, copper carbonate/alumina oxide, aluminum oxide, manganese oxide, manganese oxide/alumina oxide, manganese oxide/zinc oxide, zinc oxide/iron oxide, calcium oxide, calcium oxide/alumina oxide, lead oxide/alumina oxide, platinum/alumina oxide, activated carbon catalyst, and activated carbon catalyst - copper chloride impregnated catalyst compounds.

[0025] Each reactor vessel 38 A-F is fluidically connected to both a first outlet manifold 50 and a second outlet manifold 52 into which the fluid streams leaving the reactor vessels 38 A-F may be directed. The second outlet manifold 52 joins the first outlet manifold 50 near an outlet 53 of the catalyst test unit 20. A partial flow meter 54 is positioned in the second outlet manifold 52. First isolation valves 56A-F are positioned between each reactor vessel 38A-F and the first outlet manifold 50 and second manifold isolation valves 58A-F are positioned between each reactor vessel 38 A-F and the second outlet manifold 52. Selective opening or closing of the first and second isolation valves 56A-F, 58A-F determines whether the flow through each of the reactor vessels 38 A-F is directed to the first outlet manifold 50 or to the second outlet manifold 52. The first and second outlet manifolds 50, 52 allow flow through a single reactor vessel 38 to be diverted though the individual flow meter 54 in the second outlet manifold 52 while the flow of gas to the other five reactors 38 flows through the parallel first outlet manifold 50 so that the individual isolation valves 40 A-F for each reactor can be positioned to set the desired flow through each reactor. [0026] For example, the schematic representation of the catalyst test unit 20 in FIG. 5 illustrates the manifold isolation valves 56A-F, 58A-F positioned for flow testing and setting the position of the individual metering valve 4OF for reactor vessel 38F. The outlet isolation valve 56F for vessel 38 F leading to the first outlet manifold 50 is closed and the outlet isolation valve 58F leading to the second outlet manifold 52 is open so the flow through reactor vessel 38F is directed to the second outlet manifold 52 and can be measured by the partial flow meter 54. The flow through the remaining reactor vessels 38 A-E is directed through the first outlet manifold 50 and to the outlet 53 of the catalyst test unit 20. Thus, the position of the first and second isolation valves 56A-F₅ 58A-F allow flow through a single reactor vessel 38 to be diverted though the individual flow meter 54 while the flow of gas remains in parallel to the other five flows through the other manifold 50. With the catalyst testing unit 20 aligned in this configuration, the flow through reactor vessel 38F can be set so that one sixth of the total flow is directed through reactor vessel 38F. The catalyst test unit 20 can be successively aligned to set the flow through each of the other reactor vessels 38A- E.

[0027] The schematic representation of the catalyst test unit 20 in FIG. 6 illustrates the manifold isolation valves 56A-F, 58A-F lined up for flow through all the reactor vessels 38 A-F directed to the First outlet manifold 50 with the flow meters 28, 54 isolated, as would be preferable when the partial flows through the reactor vessels 38 A-F have been equalized so that catalyst testing can take place.

[0028] The catalyst test unit 20 desirably includes a protective frame 70 made of corrosion resistant tubing members 72. The reactor vessels 38 A-F are supported by cross members 74 of the protective frame 70. In one embodiment, the protective frame 70 has a height H of about 3 feet, a width W of about 3 feet and a length L of about 3 feet. The 3' x 3' x 3' protective frame 70 is desirable so that the catalyst test unit 20 can fit on a standard size pallet for convenient transport to a natural gas facility so the catalyst test unit 20 can test catalysts at the site. Additionally, the frame 70 of the catalyst test unit 20 may be partially disassembled to fit into the back of a small truck or sport utility vehicle and fit through standard dwelling door frames. The catalyst test unit 20 is desirable construction of a corrosion resistant material, such as 316L stainless steel for external corrosion resistance while exposed at the plant site. The 316L stainless steel construction of the reactor vessels 38 A-F and tubing members 72 also allows for reasonable passivation and corrosion resistance of the acid gas contaminant (i.e., H₂S, CO₂).

[0029] Each reactor vessel 38A-F on the catalyst test unit 20 desirably can be disassembled by unbolting it from the protective frame 70 and the inlet and outlet manifolds 24, 50, 52. In the illustrated embodiment, the reactor vessels 38A-F have removable top vessel heads or flanges 80 and bottom vessel heads or flanges 82 that can be removed from a cylindrical body portion 84. The top and bottom vessel heads 80, 82 seal a cylindrical body portion 84 with a long bolt assembly 85 and suitable bolts or fasteners 86 and contain fluid tight seals that are desirably made of Viton. The Viton seals are rated for maximum temperatures of between about 212 F up to about 400 F. However, it is conceivable that the catalyst test unit 20 may be used with catalysts that operate at higher temperatures in which case the seals would be made of a more temperature resistant material. In one preferred embodiment, the catalyst test unit 20 is designed to facilitate testing of catalyst in the absorbent removal of sulfur contaminants from natural gas or natural gas liquids at a temperature of about 40 F up to about 140 F and a natural gas pressure range from a few pounds per square inch up to about 1,100 psig. In the illustrated embodiment, the catalyst test unit 20 could be operated up to 1,800 psig as the knock out vessel 32 is the lowest pressure rated component on the catalyst test unit 20 and has a maximum working pressure of 1,800 psig. The primary reason for such over design is to ensure safety at working (testing) pressures at the customer's plant site as well as safety for any person working around or on the catalyst test unit 20.

[003Oj With the reactor vessel 38 removed from the protective frame 70, the top and bottom vessel heads 80, 82 can be removed so that the catalyst material in the reactor vessel 38 may be systematically removed and analyzed. Referring now to FIG. 7, one desirable method of removing the catalyst includes inserting the top side of the removed reactor vessel 38 into a jig 90. The jig 90 has a concentric depression 92 that allows the top flange 80 of the reactor vessel 38 to fit tightly while the bottom flange 82 is unbolted and removed. With the bottom flange 82 removed, a threaded rod and piston assembly 94 is then inserted into the bottom of the reactor vessel 38. Desirably, the threaded rod and piston assembly 94 has two constricting bands 96 that grip and hold the cylinder portion 84 of the reactor vessel 38 while a piston 98 is inserted into the open bottom of the cylinder portion 84 to make contact with the bottom of the catalyst bed within the cylinder 84. Referring now to FIG. 8, the threaded rod and piston assembly 94 is flipped 180 degrees and attached to a vise 100. The jig 90 is then removed so that the top flange 80 can be unbolted. A funnel 102 may be placed over the top opening of the cylinder 84 containing the spent catalyst. The piston 98 can be incrementally forced upward with a threaded rod 104 to expel the catalyst from the cylinder 84. The funnel 102 keeps the catalyst from overflowing so that it may be removed for thin layer analysis. In this manner, the whole catalyst bed can be analyzed in multiple points in any strata. The threaded rod and piston assembly 94 thereby allows the spent catalyst material to be removed from the vessel in thin wafer slices. By allowing the spent catalyst to be removed from the vessel 38 in thin wafer slices, statistical precision of catalyst loading data may be improved.

[0031] A common objective of catalyst evaluation testing is to produce or provide a comparison of absorbance capacity based on the use of each of a plurality of catalyst samples in order to determine which catalyst sample is most suitable for use in connection with the natural gas at a given facility. As identified above, to facilitate comparisons of absorbance capacity for various catalyst samples, it is desirable that there exist a common basis for comparison. It is preferred to compare the absorbance of the catalyst samples under identical testing conditions in the field to determine which of the catalyst samples exhibits the most preferred performance. Thus, in general terms, the invention applies an approach for simultaneously testing a plurality of catalyst samples. The invention provides an approach that is rapid and yet provides an accurate basis for comparison of catalyst performance characteristics determined for each of a plurality of catalyst samples.

[0032] While this invention has been described in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of this invention, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this invention.

Claims

What is claimed is:

1. A catalyst test unit for use in simultaneously exposing a plurality of catalyst samples to contaminants in a fluid stream, the catalyst test unit comprising: an inlet isolation valve for controlling the flow of the fluid stream into the catalyst test unit; an inlet manifold receiving the fluid steam, said inlet manifold separating into a plurality of individual branches such that each branch receives a portion of the fluid stream; a knock out vessel configured to remove water droplets from the fluid stream passing through the inlet manifold; a total flow meter configured to measure the flow rate of the fluid stream in the inlet manifold; a plurality of catalyst-containing reactor vessels, wherein each of the plurality of individual branches is fluidically connected with one of said reactor vessels such that the portion of the fluid stream in each branch is exposed to the catalyst in its respective reactor vessel; first and second outlet manifolds fluidically connected to outlets of the plurality of reactor vessels; first and second outlet isolation valves for each of the plurality of reactor vessels, said first and second outlet isolation valves positioned so that the portion of the fluid stream passing through each reactor vessel can be directed to either the first or second outlet manifold; and an individual flow meter configured to measure the flow rate of a fluid stream in the second outlet manifold.

2. The catalyst test unit of claim 1 further comprising a protective frame at least partially enclosing the reactor vessels and inlet and outlet manifolds.

3. The catalyst test unit of claim 2 wherein the protective frame is stainless steel.

4. The catalyst test unit of claim 2 wherein the protective frame has a height H of about 3 feet, a width W of about 3 feet and a length L of about 3 feet.

5. The catalyst test unit of claim 2 wherein the protective frame is made of corrosion resistant tubing members and the reactor vessels are supported by cross members of the protective frame.

6. The catalyst test unit of claim 1 wherein the reactor vessels are in parallel between the inlet manifold and the outlet manifolds.

7. The catalyst test unit of claim 1 wherein each reactor vessel can be removed from the catalyst test unit by unbolting it from the protective frame and the inlet and outlet manifolds.

8. The catalyst test unit of claim 1 wherein the reactor vessels have removable top vessel heads and bottom vessel heads and a cylindrical body portion.

10. The catalyst test unit of claim 1 wherein the catalyst in the reactor vessel is systematically removed using a threaded rod and plunger piston assembly, thereby allowing the spent catalyst material to be removed from the vessel in thin wafer slices.