CA2156234A1 - Dynamic fouling test procedure - Google Patents
Dynamic fouling test procedureInfo
- Publication number
- CA2156234A1 CA2156234A1 CA 2156234 CA2156234A CA2156234A1 CA 2156234 A1 CA2156234 A1 CA 2156234A1 CA 2156234 CA2156234 CA 2156234 CA 2156234 A CA2156234 A CA 2156234A CA 2156234 A1 CA2156234 A1 CA 2156234A1
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- Prior art keywords
- test
- stream
- additive
- fluid
- fouling
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
- G01N17/008—Monitoring fouling
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/26—Oils; viscous liquids; paints; inks
- G01N33/28—Oils, i.e. hydrocarbon liquids
- G01N33/2805—Oils, i.e. hydrocarbon liquids investigating the resistance to heat or oxidation
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- Immunology (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Medicinal Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Food Science & Technology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
A novel dynamic fouling test process is disclosed.
According to the process, a portion of a flowing fluid is diverted into a plurality of test streams. An additive to be tested is added to at least one of the test streams. A test stream to which the additive was added is directed to contact a first heated metal surface for a period of time, the metal surface having a mechanism for heating the surface. A second test stream is directed to contact a second heated metal surface for a time, the second heated metal surface having a mechanism for heating the surface. Then the accumulations of fouling on the two metal surfaces are measured and compared.
Related apparatus are also disclosed.
According to the process, a portion of a flowing fluid is diverted into a plurality of test streams. An additive to be tested is added to at least one of the test streams. A test stream to which the additive was added is directed to contact a first heated metal surface for a period of time, the metal surface having a mechanism for heating the surface. A second test stream is directed to contact a second heated metal surface for a time, the second heated metal surface having a mechanism for heating the surface. Then the accumulations of fouling on the two metal surfaces are measured and compared.
Related apparatus are also disclosed.
Description
21~6234 DYNAMIC FOULING TEST PROCEDURE
Backqround of the Invention 1. Field of the Invention The present invention relates to procedures for carrying out fouling tests in the field, and more particularly to on-line monitoring of fouling and on-line measurement of anti-foulant performance.
Backqround of the Invention 1. Field of the Invention The present invention relates to procedures for carrying out fouling tests in the field, and more particularly to on-line monitoring of fouling and on-line measurement of anti-foulant performance.
2. Description of the Prior Art Fouling is a problem associated with certain fluids in a variety of common situations. For example, fouling is a major problem encountered in the treatment of various hydrocarbon charge stocks in oil refineries, where the stocks are converted into valuable heating and transportation fuels and petrochemical feedstocks. The fouling is manifested as deposits that are formed frequently on the metal surfaces of the processing equipment and tend naturally to decrease the efficiency of the intermediate processing operations. The results of fouling appear in the form of heat transfer loss, pressure drop, loss in throughput rate and an increase in corrosion of the equipment.
Thus, techniques have been developed in an effort to decrease fouling, many of which involve the application of chemical additives that inhibit fouling. However, such additives inhibit the fouling to varying degrees of efficacy and variations among fouling situations mean that antifoulants suitable in one situation are .
unacceptable in another. Thus, an additive of ideal characteristics, including that of efficacy, and that has universal application has not been developed. Moreover, efficacy in a particular situation depends on a large number of variables making predictions impossible or at least impractical.
As a result, a trial and error approach typically is taken to determine whether a particular proposed anti-foulant would be suitable in the situation of o concern. However, because of the dangers of failures leading to continued fouling, of damaging equipment, of contamination of the system to be treated, of resulting shut-downs and of the need to dismantle the system to determine efficacy by inspection of the equipment, it is desirable to conduct such trials in a manner other than by subjecting the system to be treated to the experiment.
U.S. Patent No. 4,383,438 to Eaton describes apparatus and procedures for carrying out static fouling tests in a laboratory environment. The fouling tests of that patent are designed to simulate a heat exchanger surface such as a particular section of a heated exchanger tube exposed to a fouling liquid medium.
These tests represented a significant advancement over the prior art techniques for testing fouling conditions and the efficacy of antifoulants. However, the tests still depend on approximation of actual field conditions and so are not as reliable as desired in predicting fouling tendency in the field.
` 21~6234 In the field, hydrocarbon fluids that exhibit fouling tendencies flow through pipelines, heat exchangers and the like and encounter a variety of conditions that may not be able to be discovered (at least not without disrupting the system) or duplicated in a laboratory test such as that of the Eaton patent.
Moreover, the fluids flow at significant velocities.
Fiuid velocity has been found to be an important factor in fouling, particularly in the effect its shear forces have on deposits. Thus, static fouling tests are particularly unreliable in predicting fouling in dynamic field operations because they cannot duplicate satisfactorily the velocity of fluid flow in the field.
Moreover, inaccuracy is inherent in static tests since the metal surface is exposed to a set volume of fluid rather than the continuous flow, high fluid volume encountered by field surfaces. Continuous flow in the lab is impractical because of the volume of fluid that would be required for a continuous flow that may be carried out over a testing period that can last weeks.
The technique of the Eaton patent employs a stirring rotor to approximate the effect of the fluid velocity, but still relies on a simulation of the true flow of velocity and other field conditions, as well as on a set volume of fluid rather than a continuous flow. Other techniques feature continuous flow, but sacrifice the fluid velocity to minimize fluid use or loss.
Thus, techniques have been developed in an effort to decrease fouling, many of which involve the application of chemical additives that inhibit fouling. However, such additives inhibit the fouling to varying degrees of efficacy and variations among fouling situations mean that antifoulants suitable in one situation are .
unacceptable in another. Thus, an additive of ideal characteristics, including that of efficacy, and that has universal application has not been developed. Moreover, efficacy in a particular situation depends on a large number of variables making predictions impossible or at least impractical.
As a result, a trial and error approach typically is taken to determine whether a particular proposed anti-foulant would be suitable in the situation of o concern. However, because of the dangers of failures leading to continued fouling, of damaging equipment, of contamination of the system to be treated, of resulting shut-downs and of the need to dismantle the system to determine efficacy by inspection of the equipment, it is desirable to conduct such trials in a manner other than by subjecting the system to be treated to the experiment.
U.S. Patent No. 4,383,438 to Eaton describes apparatus and procedures for carrying out static fouling tests in a laboratory environment. The fouling tests of that patent are designed to simulate a heat exchanger surface such as a particular section of a heated exchanger tube exposed to a fouling liquid medium.
These tests represented a significant advancement over the prior art techniques for testing fouling conditions and the efficacy of antifoulants. However, the tests still depend on approximation of actual field conditions and so are not as reliable as desired in predicting fouling tendency in the field.
` 21~6234 In the field, hydrocarbon fluids that exhibit fouling tendencies flow through pipelines, heat exchangers and the like and encounter a variety of conditions that may not be able to be discovered (at least not without disrupting the system) or duplicated in a laboratory test such as that of the Eaton patent.
Moreover, the fluids flow at significant velocities.
Fiuid velocity has been found to be an important factor in fouling, particularly in the effect its shear forces have on deposits. Thus, static fouling tests are particularly unreliable in predicting fouling in dynamic field operations because they cannot duplicate satisfactorily the velocity of fluid flow in the field.
Moreover, inaccuracy is inherent in static tests since the metal surface is exposed to a set volume of fluid rather than the continuous flow, high fluid volume encountered by field surfaces. Continuous flow in the lab is impractical because of the volume of fluid that would be required for a continuous flow that may be carried out over a testing period that can last weeks.
The technique of the Eaton patent employs a stirring rotor to approximate the effect of the fluid velocity, but still relies on a simulation of the true flow of velocity and other field conditions, as well as on a set volume of fluid rather than a continuous flow. Other techniques feature continuous flow, but sacrifice the fluid velocity to minimize fluid use or loss.
3 9212 21~6234 Accordingly, dynamic tests are needed for monitoring and measuring fouling tendencies under more realistic field conditions that can take into account both fluid velocity and continuous flow without substantial fluid loss.
SummarY of the Invention The present invention, therefore, is directed to a novel method for dynamic fouling test process.
According to the process, a portion of a flowing fluid is diverted into a plurality of test streams. An additive to be tested is added to at least one of the test streams. A test stream to which the additive was added is directed to maintain contact with a first heated metal surface for a time period sufficient to allow fouling to accumulate on the metal surface. The heated metal surface has means for heating the surface. A second test stream is directed to maintain contact with a second heated metal surface for a second time period, preferably about the same time period as the first stream maintained contact with the first heated surface. The second heated metal surface has means for heating thé second metal surface. The accumulation of fouling on the two metal surfaces is measured and the accumulation on the first metal surface is compared to the accumulation on the second metal surface.
The present invention is also directed to a novel apparatus for dynamic testing of the foulin~ tendency of a flowing fluid. The apparatus comprises a slip stream
SummarY of the Invention The present invention, therefore, is directed to a novel method for dynamic fouling test process.
According to the process, a portion of a flowing fluid is diverted into a plurality of test streams. An additive to be tested is added to at least one of the test streams. A test stream to which the additive was added is directed to maintain contact with a first heated metal surface for a time period sufficient to allow fouling to accumulate on the metal surface. The heated metal surface has means for heating the surface. A second test stream is directed to maintain contact with a second heated metal surface for a second time period, preferably about the same time period as the first stream maintained contact with the first heated surface. The second heated metal surface has means for heating thé second metal surface. The accumulation of fouling on the two metal surfaces is measured and the accumulation on the first metal surface is compared to the accumulation on the second metal surface.
The present invention is also directed to a novel apparatus for dynamic testing of the foulin~ tendency of a flowing fluid. The apparatus comprises a slip stream
4 9212 :- 21~6234 conduit for divergence of a slip stream from a flow of fluid to be tested, a plurality of test stream conduits in fluid communication with the slip stream conduit and means for dividing a flow of fluid in the slip stream conduit into the plurality of test stream conduits, means for introduction of an additive into at least one of the test stream conduits, and a heated metal surface in each test stream conduit located so that the heated metal surface may be exposed to a fluid flowing through the lo test stream conduit for a time period sufficient to allow fouling to accumulate on the metal surface, the metal surface having means for heating the surface.
Among the several advantages of this invention, may be noted the provision of a method for carrying out fouling tests in the field; the provision of such method that permits on-line monitoring of fouling and on-line measurement of anti-foulant performance; the provision of such method that permits measurement of fouling tendency in the field under more realistic conditions; the provision of such method that permits measurement of fouling tendency under field-like high velocity, continuous flow conditions without substantial fluid loss; and the provision of apparatus useful in carrying out such method.
:
~ 21562~4 Brief DescriPtion of the Drawings Fig. 1 is a schematic representation of a typical refinery unit side stream adapted with apparatus for carrying out the test procedure of the invention; and S Fig. 2 is a view of the testing device of the invention shown in place in a conduit of the invention, the conduit being shown in cross-section.
Detailed Description of the Preferred Embodiments In accordance with the present invention, it has 1~ been discovered that by diverting a slip stream from a flow of fluid, such as from refinery unit side streams, to at least two test streams running in parallel and including heated metal surfaces, injecting an additive to one of the test streams and comparing the fouling on the heated metal surface from that stream to the fouling on a similar heated metal surface in a simllar stream to which the additive has been injected under different conditions or to which no additive or a second additive has been injected, a more realistic test of anti-foulant efficacy can be achieved than with standard static fouling test methods. The test is carried out on the actual fluid of concern. And, by contrast with such prior art static tests, this new dynamic test procedure permits continual renewal of the fluid being tested and takes into account the fluid velocity and so reflects actual field conditions more accurately without significant fluid loss.
Moreover, the new test procedure can be controlled to simulate a variety of conditions and to test the effects of various parameters. Thus, the time of operation, the heat transfer rate, the heat exchanger S skin temperature, the additive type, the additive injection rate and the operating mode (i.e., operation at constant heat transfer rate or constant skin temperature) can be selected. In fact, for instance, for fluid flow directed to a series of heat exchangers as may be encountered in a refinery unit side stream, by adjusting the skin temperature, any heat exchanger in the series can be simulated for fouling rate studies. Not only that, but by returning the test streams to the flow of fluid after comparing the fouling, fluid loss is eliminated.
Referriny now to Fig. 1, a typical refinery unit side stream adapted with apparatus for carrying out the test procedure of this invention is illustrated.
Although the test procedure and apparatus of this invention may be applied to any flow of fluid, the particular stream of Fig. 1 is shown for purposes of explanation and understanding of a typical environment for this invention. This invention is especially well suited to testing fouling of heat exchangers and so to application to fluid flow to heat exchangers, the invention may be adapted by the same methods to a wide variety of fluid streams.
21562~4 While the present test procedure may be employed for any of a wide variety of media having a tendency to foul metal surfaces such as heat exchanger surfaces, it is particularly well suited for testing of hydrocarbon fluids, especially crude oil. Such hydrocarbon fluids contain hydrocarbons, but also various other components or impurities investing in the fluid its tendency to foul metal surfaces.
In the particular stream illustrated in Fig. 1, crude oil from a desalter 5 is directed along a major conduit 10 and pumped by a pump 12 to a series of heat exchangers 1~, 16, 18, 20 and 22 to a furnace 24. An antifoulant or other chemical additive may be added to the stream by way of pump 26 at injection point P.
As shown in Fig. 1, a small slip stream may be diverted from the stream flowing through conduit 10 and studied with apparatus of this invention, which may be described as a refinery exchanger fouling simulator. In particular, gate valves 28 and 30 may be opened to create a slip stream. The slip stream flows through valve 28 and then is divided into two or more sub-streams running in parallel. Fig. 1 shows two substreams identified as ~a~ and "b", with each element associated with the sub-streams to be discussed below designated ~a~ and "b", respectively, to indicate association with the correspollding sub-stream. Thus, for example, a pump designated 32 would be identified as 32a in a sub-stream ~a~ and as 32b in sub-stream ~b~. Each sub-stream is -- 2156~34 carried by a conduit of, for example, three-quarter or one inch in diameter, permitting a flow rate as desired, such as about five to eight gallons per minute. However, other diameters and flow rates may be employed as appropriate for the system. Flow rate also can be varied by changing the pipe diameter or by changing the pump design or by adding additional piping to divert flow.
The substream temperature is the same as that of the flow from which is diverted; for instance, about 250F
lo (about lZ0C). Alternatively, the substreams may be equipped with a heat exchanger for varying the temperature, such as from about 250F (120C) to about 580F (300C).
For at least one of the sub-streams, a pump 32 is - 15 provided to permit injection at point C of a chemical additive to be tested. At least one of the sub-streams may be left untreated as a control or comparison to the treated sub-stream or sub-streams. Alternatively, all sub-streams may be treated, with the additive type or additive injection rate varied, or all sub-streams may be treated equally simply to show a favorable comparison of fouling tendency.
The sub-streams also may be adapted to account for the residence times and mixing of the tested additives in the stream 10. Thus, in the on-line additive treatment of stream 10 via injection by pump 26, the design of the refinery piping system (i.e., the length, diameter and layout of the piping) and the location of additive -21~62~4 , injection causes the additive to remain in and mix with the hydrocarbon in stream 10 for some amount of residence time. The residence time varies from refinery unit to refinery unit`and from refinery to refinery. The present invention takes the residence time and mixing into account.
In order to simulate the residence time of the additive in the main stream 10, the residence time of the additive in the substream may be increased such as by increasing the diameter of the conduit carrying the treated substream so that the conduit has an increased diameter for a selected length, and then reducing the diameter back to the original (or some other desired) diameter. This section is designate in Fig. 1 by the box marked ~R~. Thus, a wide variety of residence times may be accommodated by varying the flow rate, the degree of increase in diameter of the substream conduit and the length of the section of the conduit having increased diameter. Illustrative, but not limiting, of typical residence times that may be desired is the range of about one-half to about three minutes, such as about forty-five to fifty seconds.
The effect of mixing of additive with the hydrocarbon stream lO may be simulated in the substreams by the inclusion of one or more static, in-line mixing elements, the number of such mixing elements being dependent on the degree of mixing to be simulated. Such mixing elements are designated in Fig. 1 as 33. In `~ ` C?/5(P~
addition, pulsation dampening equipment can be included on the additive injection pumps 32, if so desired, to eliminate the effect of pulsed additive injection.
Injection quills also can be included as needed to match the system being simulated.
The pressure of the sub-stream then is increased by pump 34 and the sub-stream is directed to a testing device 36. The testing device includes a heat exchanger which provides a heated metal surface against which the fluid flows and on which fouling deposits may accumulate.
The heated metal surface may be a heated probe as described in U.S. Patent No. 4,383,438 to Eaton. Fig. 2 illu-strates the testing device, with the conduit shown in cross-section.
testing device, with the conduit shown in cross-section.
The sub-stream flows through conduit 38 in the direction of arrow 42 to a T-shaped section, with the branch of the T-shaped section opposite the flowing stream capped with the probe 44 so that the fluid flows into the end 46 of the probe and is routed away to flow in the direction of arrow 48, at right angle to arrow 42. The probe 44 is affixed to the T-section by means of fiange 52 and is configured as described in the noted patent to Eaton.
Therefore, the probe comprises a metallic housing 54 enclosing an electrical resistance heating element and a thermocouple in contact with the inner wall of housing 54. The heating element and thermocouple are not shown in Fig. 2, but are shown and discussed in the Eaton patent. The metallic housing 54 most desirably should be A
21~6234 of the same metal as the surfaces for which fouling is a concern in the system. Thus, if the fouling tendency of steel heat exchangers in the system is to be studied, the metallic housing 54 would be of the same type of steel as the heat exchangers.
As noted, the Eaton probe is just one possible heat exchanger that may be used. In other versions of the heat exchanger or metal surface, the fluid may contact the surface by flowing across the surface (i.e., it may flow parallel to and along the surface), by striking the surface obliquely or by striking the surface head on.
Possible embodiments of the heated metal surface include, for example, an electrically heated tube through which the fluid flows inside as opposed to outside the tube may be used. Or, a shell-in-tube heat exchanger, with a heating oil and heater added to provide a hot fluid for the shell side may be used with the fluid passing through the tubes. It is simply necessary that a heated metal surface be provided for exposure to the fluid flow. The flowing fluid maintains contact with the metal surface (that is, it flows along or against itj for a desired period of time to evaluate the fouling tendency of the fluid.
If the Eaton device is used, electrical leads 56 and 58 extend from the resistance heating element and the thermocouple, respectively, to the outside of the probe and conduit. Electrical leads 56 connect with a constant current power source shown in the Eaton patent, but not :'.;'.: 21~62~i in Fig. 2 herein. Electrical lead 58 connects with a temperature gauge, which in turn preferably is connected to a temperature recording device. The gauge and recording device are shown in the Eaton patent, but not in Fig. 2 herein. Alternatively, other heating and temperature measurement techniques may be employed; for example, a control panel with measuring devices, and a different type of power source and recordlng and controlling devices may be used.
Thus, the temperature of the surface of the metallic housing of the Eaton probe (i.e., the skin temperature) may be adjusted to the temperature of the surfaces for which fouling is a concern. If another type of metal surface is used instead of the Eaton probe, temperature may be controlled in a similar manner or by standard techniques for the heat exchanger employed for the metal surface.
If desired, a heat exchanger may be placed in the line before the metal surface as noted above to adjust the temperature of the flowing fluid as well. Means for measuring the temperature of the fluid flowing to the metal surface should be provided in addition to the means for measuring the temperature of the metal surface.
Thus, whereas the apparatus of Eaton required a vessel and rotor in an effort to simulate field conditions, the present device is placed in the actual field setting and exposed to field conditions, and the vessel and rotor are unnecessary. However, the metal C~/5~ 3S~
surface is equipped with a control cabinet to provide for control of the heated probe voltages using either the heated metal surface temperature or the delivered wattage as a control parameter. The control cabinet should also contain a datalogging means to record the performance for analysis. By measuring and comparing the fouling rates on the probes, antifoulant performance can be determined.
According to this technique, therefore, any of the time of operation, the additive type, the additive injection rate, the operating mode (that is, for example, running at constant heat transfer rate or constant skin temperature), the heat transfer rate of the heat exchanger simulated and the skin temperature of the heat exchanger simulated (the latter two be interdependent), may be control and varied and any of the other variables and resultant fouling rate can be measured. As a result, the dependency of fouling rate of a particular variable of concern can be studied.
After flowing past the metal surface, the substreams may be reunited at the T juncture 60 and directed via conduit 62, through gate valve 30 and back to the main conduit 10, eliminating waste of fluid otherwise encountered during standard tests. Between runs, the probe may be cleaned by first closing gate valves 28 and 30 and then opening flange 52 to remove the metal surface. The metal surface may then be cleaned as discussed in the Eaton patent.
21S623~ `
.
In view of the above, it will be seen that the several advantages of the invention are achieved and other advantageous results attained.
As various changes could be made in the above methods and compositions withou~ departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
Among the several advantages of this invention, may be noted the provision of a method for carrying out fouling tests in the field; the provision of such method that permits on-line monitoring of fouling and on-line measurement of anti-foulant performance; the provision of such method that permits measurement of fouling tendency in the field under more realistic conditions; the provision of such method that permits measurement of fouling tendency under field-like high velocity, continuous flow conditions without substantial fluid loss; and the provision of apparatus useful in carrying out such method.
:
~ 21562~4 Brief DescriPtion of the Drawings Fig. 1 is a schematic representation of a typical refinery unit side stream adapted with apparatus for carrying out the test procedure of the invention; and S Fig. 2 is a view of the testing device of the invention shown in place in a conduit of the invention, the conduit being shown in cross-section.
Detailed Description of the Preferred Embodiments In accordance with the present invention, it has 1~ been discovered that by diverting a slip stream from a flow of fluid, such as from refinery unit side streams, to at least two test streams running in parallel and including heated metal surfaces, injecting an additive to one of the test streams and comparing the fouling on the heated metal surface from that stream to the fouling on a similar heated metal surface in a simllar stream to which the additive has been injected under different conditions or to which no additive or a second additive has been injected, a more realistic test of anti-foulant efficacy can be achieved than with standard static fouling test methods. The test is carried out on the actual fluid of concern. And, by contrast with such prior art static tests, this new dynamic test procedure permits continual renewal of the fluid being tested and takes into account the fluid velocity and so reflects actual field conditions more accurately without significant fluid loss.
Moreover, the new test procedure can be controlled to simulate a variety of conditions and to test the effects of various parameters. Thus, the time of operation, the heat transfer rate, the heat exchanger S skin temperature, the additive type, the additive injection rate and the operating mode (i.e., operation at constant heat transfer rate or constant skin temperature) can be selected. In fact, for instance, for fluid flow directed to a series of heat exchangers as may be encountered in a refinery unit side stream, by adjusting the skin temperature, any heat exchanger in the series can be simulated for fouling rate studies. Not only that, but by returning the test streams to the flow of fluid after comparing the fouling, fluid loss is eliminated.
Referriny now to Fig. 1, a typical refinery unit side stream adapted with apparatus for carrying out the test procedure of this invention is illustrated.
Although the test procedure and apparatus of this invention may be applied to any flow of fluid, the particular stream of Fig. 1 is shown for purposes of explanation and understanding of a typical environment for this invention. This invention is especially well suited to testing fouling of heat exchangers and so to application to fluid flow to heat exchangers, the invention may be adapted by the same methods to a wide variety of fluid streams.
21562~4 While the present test procedure may be employed for any of a wide variety of media having a tendency to foul metal surfaces such as heat exchanger surfaces, it is particularly well suited for testing of hydrocarbon fluids, especially crude oil. Such hydrocarbon fluids contain hydrocarbons, but also various other components or impurities investing in the fluid its tendency to foul metal surfaces.
In the particular stream illustrated in Fig. 1, crude oil from a desalter 5 is directed along a major conduit 10 and pumped by a pump 12 to a series of heat exchangers 1~, 16, 18, 20 and 22 to a furnace 24. An antifoulant or other chemical additive may be added to the stream by way of pump 26 at injection point P.
As shown in Fig. 1, a small slip stream may be diverted from the stream flowing through conduit 10 and studied with apparatus of this invention, which may be described as a refinery exchanger fouling simulator. In particular, gate valves 28 and 30 may be opened to create a slip stream. The slip stream flows through valve 28 and then is divided into two or more sub-streams running in parallel. Fig. 1 shows two substreams identified as ~a~ and "b", with each element associated with the sub-streams to be discussed below designated ~a~ and "b", respectively, to indicate association with the correspollding sub-stream. Thus, for example, a pump designated 32 would be identified as 32a in a sub-stream ~a~ and as 32b in sub-stream ~b~. Each sub-stream is -- 2156~34 carried by a conduit of, for example, three-quarter or one inch in diameter, permitting a flow rate as desired, such as about five to eight gallons per minute. However, other diameters and flow rates may be employed as appropriate for the system. Flow rate also can be varied by changing the pipe diameter or by changing the pump design or by adding additional piping to divert flow.
The substream temperature is the same as that of the flow from which is diverted; for instance, about 250F
lo (about lZ0C). Alternatively, the substreams may be equipped with a heat exchanger for varying the temperature, such as from about 250F (120C) to about 580F (300C).
For at least one of the sub-streams, a pump 32 is - 15 provided to permit injection at point C of a chemical additive to be tested. At least one of the sub-streams may be left untreated as a control or comparison to the treated sub-stream or sub-streams. Alternatively, all sub-streams may be treated, with the additive type or additive injection rate varied, or all sub-streams may be treated equally simply to show a favorable comparison of fouling tendency.
The sub-streams also may be adapted to account for the residence times and mixing of the tested additives in the stream 10. Thus, in the on-line additive treatment of stream 10 via injection by pump 26, the design of the refinery piping system (i.e., the length, diameter and layout of the piping) and the location of additive -21~62~4 , injection causes the additive to remain in and mix with the hydrocarbon in stream 10 for some amount of residence time. The residence time varies from refinery unit to refinery unit`and from refinery to refinery. The present invention takes the residence time and mixing into account.
In order to simulate the residence time of the additive in the main stream 10, the residence time of the additive in the substream may be increased such as by increasing the diameter of the conduit carrying the treated substream so that the conduit has an increased diameter for a selected length, and then reducing the diameter back to the original (or some other desired) diameter. This section is designate in Fig. 1 by the box marked ~R~. Thus, a wide variety of residence times may be accommodated by varying the flow rate, the degree of increase in diameter of the substream conduit and the length of the section of the conduit having increased diameter. Illustrative, but not limiting, of typical residence times that may be desired is the range of about one-half to about three minutes, such as about forty-five to fifty seconds.
The effect of mixing of additive with the hydrocarbon stream lO may be simulated in the substreams by the inclusion of one or more static, in-line mixing elements, the number of such mixing elements being dependent on the degree of mixing to be simulated. Such mixing elements are designated in Fig. 1 as 33. In `~ ` C?/5(P~
addition, pulsation dampening equipment can be included on the additive injection pumps 32, if so desired, to eliminate the effect of pulsed additive injection.
Injection quills also can be included as needed to match the system being simulated.
The pressure of the sub-stream then is increased by pump 34 and the sub-stream is directed to a testing device 36. The testing device includes a heat exchanger which provides a heated metal surface against which the fluid flows and on which fouling deposits may accumulate.
The heated metal surface may be a heated probe as described in U.S. Patent No. 4,383,438 to Eaton. Fig. 2 illu-strates the testing device, with the conduit shown in cross-section.
testing device, with the conduit shown in cross-section.
The sub-stream flows through conduit 38 in the direction of arrow 42 to a T-shaped section, with the branch of the T-shaped section opposite the flowing stream capped with the probe 44 so that the fluid flows into the end 46 of the probe and is routed away to flow in the direction of arrow 48, at right angle to arrow 42. The probe 44 is affixed to the T-section by means of fiange 52 and is configured as described in the noted patent to Eaton.
Therefore, the probe comprises a metallic housing 54 enclosing an electrical resistance heating element and a thermocouple in contact with the inner wall of housing 54. The heating element and thermocouple are not shown in Fig. 2, but are shown and discussed in the Eaton patent. The metallic housing 54 most desirably should be A
21~6234 of the same metal as the surfaces for which fouling is a concern in the system. Thus, if the fouling tendency of steel heat exchangers in the system is to be studied, the metallic housing 54 would be of the same type of steel as the heat exchangers.
As noted, the Eaton probe is just one possible heat exchanger that may be used. In other versions of the heat exchanger or metal surface, the fluid may contact the surface by flowing across the surface (i.e., it may flow parallel to and along the surface), by striking the surface obliquely or by striking the surface head on.
Possible embodiments of the heated metal surface include, for example, an electrically heated tube through which the fluid flows inside as opposed to outside the tube may be used. Or, a shell-in-tube heat exchanger, with a heating oil and heater added to provide a hot fluid for the shell side may be used with the fluid passing through the tubes. It is simply necessary that a heated metal surface be provided for exposure to the fluid flow. The flowing fluid maintains contact with the metal surface (that is, it flows along or against itj for a desired period of time to evaluate the fouling tendency of the fluid.
If the Eaton device is used, electrical leads 56 and 58 extend from the resistance heating element and the thermocouple, respectively, to the outside of the probe and conduit. Electrical leads 56 connect with a constant current power source shown in the Eaton patent, but not :'.;'.: 21~62~i in Fig. 2 herein. Electrical lead 58 connects with a temperature gauge, which in turn preferably is connected to a temperature recording device. The gauge and recording device are shown in the Eaton patent, but not in Fig. 2 herein. Alternatively, other heating and temperature measurement techniques may be employed; for example, a control panel with measuring devices, and a different type of power source and recordlng and controlling devices may be used.
Thus, the temperature of the surface of the metallic housing of the Eaton probe (i.e., the skin temperature) may be adjusted to the temperature of the surfaces for which fouling is a concern. If another type of metal surface is used instead of the Eaton probe, temperature may be controlled in a similar manner or by standard techniques for the heat exchanger employed for the metal surface.
If desired, a heat exchanger may be placed in the line before the metal surface as noted above to adjust the temperature of the flowing fluid as well. Means for measuring the temperature of the fluid flowing to the metal surface should be provided in addition to the means for measuring the temperature of the metal surface.
Thus, whereas the apparatus of Eaton required a vessel and rotor in an effort to simulate field conditions, the present device is placed in the actual field setting and exposed to field conditions, and the vessel and rotor are unnecessary. However, the metal C~/5~ 3S~
surface is equipped with a control cabinet to provide for control of the heated probe voltages using either the heated metal surface temperature or the delivered wattage as a control parameter. The control cabinet should also contain a datalogging means to record the performance for analysis. By measuring and comparing the fouling rates on the probes, antifoulant performance can be determined.
According to this technique, therefore, any of the time of operation, the additive type, the additive injection rate, the operating mode (that is, for example, running at constant heat transfer rate or constant skin temperature), the heat transfer rate of the heat exchanger simulated and the skin temperature of the heat exchanger simulated (the latter two be interdependent), may be control and varied and any of the other variables and resultant fouling rate can be measured. As a result, the dependency of fouling rate of a particular variable of concern can be studied.
After flowing past the metal surface, the substreams may be reunited at the T juncture 60 and directed via conduit 62, through gate valve 30 and back to the main conduit 10, eliminating waste of fluid otherwise encountered during standard tests. Between runs, the probe may be cleaned by first closing gate valves 28 and 30 and then opening flange 52 to remove the metal surface. The metal surface may then be cleaned as discussed in the Eaton patent.
21S623~ `
.
In view of the above, it will be seen that the several advantages of the invention are achieved and other advantageous results attained.
As various changes could be made in the above methods and compositions withou~ departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
Claims (12)
1. A dynamic fouling test process comprising the steps of:
diverting a portion of a flowing fluid into a plurality of test streams;
adding to at least one of said test streams an additive to be tested;
directing a test stream to which the additive was added to maintain contact with a first heated metal surface for a period of time, the first heated metal surface having means for heating that surface;
directing a second test stream to maintain contact with a second heated metal surface for a desired time, the time being sufficient to allow fouling to accumulate on the second metal surface, the second heated metal surface having means for heating that surface; and measuring and comparing the accumulations of fouling on the two metal surfaces.
diverting a portion of a flowing fluid into a plurality of test streams;
adding to at least one of said test streams an additive to be tested;
directing a test stream to which the additive was added to maintain contact with a first heated metal surface for a period of time, the first heated metal surface having means for heating that surface;
directing a second test stream to maintain contact with a second heated metal surface for a desired time, the time being sufficient to allow fouling to accumulate on the second metal surface, the second heated metal surface having means for heating that surface; and measuring and comparing the accumulations of fouling on the two metal surfaces.
2. The test process of claim 1 wherein the portion of the flowing fluid that is diverted into a plurality of test streams is so diverted by diverting a single slip stream from the flowing fluid and dividing the slip stream into the test streams.
3. The test process of claim 1 wherein the portion of the flowing fluid that is diverted into a plurality of test streams is diverted into exactly two test streams.
4. The test process of claim 3 wherein the additive is added to one of the test streams and no additive is added to the other test stream.
5. The test process of claim 1 wherein the additive added to at least one of the test streams is a first additive and a second additive is added to at least one stream to which the first additive is not added.
6. The test process of claim 3 wherein the additive is added to one of the test streams and a second additive is added to the other test stream.
7. The test process of claim 1 wherein the flow of the test stream to which the additive has been added is delayed for a residence time after addition of the additive and before the stream flows about the first heated metal surface.
8. The test process of claim 1 wherein a minority of the flowing fluid is diverted, leaving a majority of the flowing fluid undiverted and further comprising the step of redirecting the test streams to the majority of the flowing fluid after the test streams flow about the heated metal surfaces.
9. The test process of claim 1 wherein the heated metal surfaces are heated metal probes about which the test stream flows.
lo. The test process of claim 1 wherein the period of time is about equal to the desired time sufficient which is to allow fouling to accumulate on the second metal surface.
lo. The test process of claim 1 wherein the period of time is about equal to the desired time sufficient which is to allow fouling to accumulate on the second metal surface.
17
11. An apparatus for dynamic testing of the fouling tendency of a flowing fluid comprising:
(a) a slip stream conduit for divergence of a slip stream from a flow of fluid to be tested;
(b) a plurality of test stream conduits in fluid communication with the slip stream conduit and means for dividing a flow of fluid in the slip stream conduit into the plurality of test stream conduits;
(c) means for introduction of an additive into at least one of the test stream conduits; and (d) a heated metal surface in each test stream conduit located so that the metal surface may be exposed to a fluid flowing through the test stream conduit for a time period sufficient to allow fouling to accumulate on the metal probe, the heated metal surface having means for heating the surface.
(a) a slip stream conduit for divergence of a slip stream from a flow of fluid to be tested;
(b) a plurality of test stream conduits in fluid communication with the slip stream conduit and means for dividing a flow of fluid in the slip stream conduit into the plurality of test stream conduits;
(c) means for introduction of an additive into at least one of the test stream conduits; and (d) a heated metal surface in each test stream conduit located so that the metal surface may be exposed to a fluid flowing through the test stream conduit for a time period sufficient to allow fouling to accumulate on the metal probe, the heated metal surface having means for heating the surface.
12. An apparatus for dynamic testing of the fouling tendency of a flowing fluid as set forth in Claim 11, further comprising:
means for directing a fluid flowing through the test stream conduits, after exposure to the heated metal surfaces, back to the flow of fluid to be tested that was not diverted as a slip stream.
means for directing a fluid flowing through the test stream conduits, after exposure to the heated metal surfaces, back to the flow of fluid to be tested that was not diverted as a slip stream.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29430094A | 1994-08-23 | 1994-08-23 | |
| US294,300 | 1994-08-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2156234A1 true CA2156234A1 (en) | 1996-02-24 |
Family
ID=23132810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2156234 Abandoned CA2156234A1 (en) | 1994-08-23 | 1995-08-16 | Dynamic fouling test procedure |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH08101117A (en) |
| CA (1) | CA2156234A1 (en) |
| GB (1) | GB2292607A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5734098A (en) * | 1996-03-25 | 1998-03-31 | Nalco/Exxon Energy Chemicals, L.P. | Method to monitor and control chemical treatment of petroleum, petrochemical and processes with on-line quartz crystal microbalance sensors |
| FR2949155B1 (en) * | 2009-08-14 | 2012-04-06 | Neosens | METHOD FOR MEASURING OR DETECTING THE REINFORCEMENT OF A REACTOR |
| KR101776443B1 (en) | 2012-07-27 | 2017-09-07 | 제너럴 일렉트릭 캄파니 | System and method for contaminant detection in fluid streams |
| JP6139230B2 (en) * | 2013-04-11 | 2017-05-31 | 三菱重工業株式会社 | Boiler steam system salinity monitoring device and monitoring method |
| US10234361B2 (en) | 2013-07-01 | 2019-03-19 | Knew Value Llc | Heat exchanger testing device |
| CN105593663A (en) | 2013-07-01 | 2016-05-18 | 价值有知有限公司 | Heat exchanger testing device |
| FR3047804B1 (en) * | 2016-02-11 | 2018-03-23 | IFP Energies Nouvelles | APPARATUS FOR ANALYSIS OF SENSITIVITY TO THE FORMATION OF DEPOSITION IN A FUEL, IN PARTICULAR IN A FUEL USED IN AERONAUTICS. |
| CA3030389C (en) * | 2016-07-14 | 2023-04-25 | Bp Corporation North America Inc. | Conditioning a sample taken from a hydrocarbon stream |
| CN115060870B (en) * | 2022-08-11 | 2022-11-29 | 中国长江三峡集团有限公司 | Geofluorine fluid scaling prediction method and device and laboratory reaction equipment |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE399765B (en) * | 1974-11-15 | 1978-02-27 | Stal Laval Apparat Ab | META DEVICE FOR SATURATION OF POLLUTION DEGREE IN HEAT EXCHANGERS AND OTHER PIPELINES |
| US4176544A (en) * | 1978-05-04 | 1979-12-04 | The British Petroleum Company Limited | Method for determining fouling |
| US4346587A (en) * | 1980-10-30 | 1982-08-31 | Drew Chemical Corporation | Process and apparatus for testing fluids for fouling and antifoulant protocol |
| US4383438A (en) * | 1981-06-02 | 1983-05-17 | Petrolite Corporation | Fouling test apparatus |
| US4910999A (en) * | 1988-11-14 | 1990-03-27 | Champion Chemicals, Inc. | Method and apparatus for conducting fouling tests |
-
1995
- 1995-08-16 CA CA 2156234 patent/CA2156234A1/en not_active Abandoned
- 1995-08-21 GB GB9517073A patent/GB2292607A/en not_active Withdrawn
- 1995-08-23 JP JP23594695A patent/JPH08101117A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08101117A (en) | 1996-04-16 |
| GB9517073D0 (en) | 1995-10-25 |
| GB2292607A (en) | 1996-02-28 |
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| EEER | Examination request | ||
| FZDE | Dead |