CN109425683B - Method for determining catalyst replacement time and proportion and method for replacing catalyst - Google Patents
Method for determining catalyst replacement time and proportion and method for replacing catalyst Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 186
- 238000000034 method Methods 0.000 title claims abstract description 89
- 230000009467 reduction Effects 0.000 claims abstract description 26
- 238000013178 mathematical model Methods 0.000 claims abstract description 18
- 230000000694 effects Effects 0.000 claims description 96
- 238000006243 chemical reaction Methods 0.000 claims description 37
- 230000008569 process Effects 0.000 claims description 28
- 238000006555 catalytic reaction Methods 0.000 claims description 27
- 238000006073 displacement reaction Methods 0.000 claims description 15
- 238000003786 synthesis reaction Methods 0.000 claims description 15
- 230000008859 change Effects 0.000 claims description 11
- 230000007423 decrease Effects 0.000 claims description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N methanol Substances OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 8
- 230000003247 decreasing effect Effects 0.000 claims description 7
- 230000001419 dependent effect Effects 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 230000003197 catalytic effect Effects 0.000 claims description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000004523 catalytic cracking Methods 0.000 claims description 2
- 238000006057 reforming reaction Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 8
- 239000007788 liquid Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000010926 purge Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 230000009849 deactivation Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/10—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using catalysis
Abstract
The invention relates to the field of chemical systems applying catalysts, and discloses a method for determining the replacement time and proportion of a catalyst, which comprises the following steps: (1) determining the target value of the catalyst: (2) carrying out space velocity reduction test, (3) establishing a mathematical model, and (4) determining the time and proportion of catalyst replacement. The method determines the catalyst replacement time and proportion by combining the test and the model, does not need the complicated test of unloading and adding the catalyst, but establishes a mathematical model on the basis of test data through a simple airspeed reduction test, thereby ensuring the accuracy of the model and not needing to verify the model again.
Description
Technical Field
The invention relates to the field of chemical systems applying catalysts, in particular to a method for determining the replacement time and proportion of a catalyst and a method for replacing the catalyst.
Background
After the catalyst is operated for a period of time in a reactor (a reactor such as a slurry bed, a fluidized bed or a fixed bed), the reactivity is reduced, which is called "deactivation". The deactivation of the catalyst can affect the normal operation of the chemical reaction, and in order to maintain the overall activity of the reactor, when the catalyst is deactivated, a part of old catalyst should be discharged from the reactor, and then a part of fresh catalyst should be added, but the discharge and the addition cannot affect the normal operation of the reactor (for example, catalyst replacement cannot be realized by stopping the reactor), namely, the catalyst replacement is realized by so-called catalyst replacement, so as to ensure that the overall activity performance of the reactor meets the requirement.
Therefore, when to start the replacement (time) and how much catalyst to replace (proportion) becomes a very critical issue.
In the prior art, the following two schemes are generally adopted to solve the problems: the first method is a test method, namely, on-line replacement is started when the performance of the catalyst is reduced, the replacement time is easy to determine, but the determination of the replacement ratio can only be carried out by a large number of trial tests, and the defect of large workload exists; in addition, the method of directly discharging and adding the catalyst has very strict requirements on a test device and operation, and the test cost is high. The second method is to use a mathematical model to obtain a mathematical model of catalyst replacement by performing simulation based on the existing performance data of the catalyst, which has the disadvantages of being heavily dependent on the accuracy of the selected model and requiring tests to verify the model.
CN105199771A discloses a slurry bed reactor catalyst replacement system and a method, wherein the replacement system comprises a slurry bed reactor, a reduction reactor and a slag wax stirred tank, the replacement method is a replacement method combining regular replacement of a catalyst and large-scale replacement of the catalyst, the regular replacement of the catalyst is specifically that the catalyst is replaced once every 5 days, the number of the catalyst replaced each time is 4.5 tons, the catalyst is replaced in large scale, and the catalyst which is reduced twice continuously is added into the slurry bed reactor once every month to complete large-scale replacement. However, the time and amount of catalyst replacement determined in the prior art are too simple to be applied to a specific type of reactor (slurry bed reactor) and a specific treatment amount system, and the ductility and generalization of the method are poor.
CN101829526A discloses a catalyst replacement system, a catalyst replacement method and a rectification column having the same, the replacement system comprising a catalyst filter (F01), a liquid collection tank (ZM02), a catalyst loading tank (ZM01), a pump (P01) and a plurality of valves, wherein the catalyst filter (F01) is in communication with a rectification column reaction tray; the liquid collection tank (ZM02) is in gas phase communication with the rectifying column reaction tray and is also in communication with the catalyst filter (F01); the catalyst loading pot (ZM01) stores new catalyst; a pump (P01) was used to pump the liquid collected by the liquid collection tank (ZM02) to the catalyst filter (F01), mix fresh catalyst with the liquid, and pump it back to the rectifier reaction tray. The catalyst can be replaced on the premise of no shutdown, so that the startup and shutdown times are reduced. However, the prior art does not describe how to determine the time and proportion of catalyst replacement, and the described method is mainly directed to a rectifying tower reaction system, and has certain limitations.
CN105817183A discloses a method for quickly removing phosgene in a catalyst during catalyst replacement of a phosgene synthesis tower. The method comprises the steps of firstly purging phosgene which is easy to desorb and adsorbed in catalyst active carbon of a phosgene synthesis tower by nitrogen purging, and then purging by ammonia gas, wherein the ammonia gas reacts with phosgene which is difficult to desorb and is contained in the catalyst of the phosgene synthesis tower. Then the phosgene synthesis tower is washed by a water gun and dried by hot gas. However, the method is only suitable for a system with a completely replaced catalyst, cannot be applied to the situation of partial catalyst replacement, and mainly aims at a phosgene synthesis tower, so that the method has certain limitation.
CN1423688A discloses a process for hydrotreating a hydrocarbon feed stream flowing upwardly through a hydroconversion reaction zone, the process comprising the steps of: a) passing a hydrocarbon feed stream in the presence of hydrogen at a reaction pressure into a hydroconversion reaction zone containing a particulate hydroprocessing catalyst to initiate upward flow of said hydrocarbon feed stream over said catalyst and recovering a reaction effluent therefrom; b) sulfiding a quantity of hydroprocessing catalyst within a treatment zone to produce sulfided catalyst; and c) adding at least a portion of the sulfided catalyst to the hydroconversion reaction zone while maintaining the reaction zone at the reaction pressure. The method is mainly suitable for the static reactors such as a hydrogenation catalyst packed bed, a fixed bed, an expansion catalyst bed and the like which take hydrocarbons as raw materials, and the application system is limited.
The prior art focuses on the establishment of a catalyst replacement method under the condition of a specific reaction system and specific treatment capacity, and does not perform essential innovation on catalyst replacement and does not establish a universal method for determining the catalyst replacement time and proportion.
Disclosure of Invention
The invention aims to overcome the defect that the catalyst replacement method in the prior art has no universality, and the method for determining the catalyst replacement time and proportion by combining the test and the model does not need the complicated test of 'discharging' and 'adding' the catalyst, but adopts the method of simply reducing the airspeed test and establishing a mathematical model on the basis of test data, thereby ensuring the accuracy of the model and not needing to verify the model again.
In order to achieve the above object, the present invention provides, in a first aspect, a method of determining catalyst replacement time and ratio, the method comprising:
(1) determining the target value of the catalyst:
the method comprises the steps of determining the target activity of a catalyst as X and the initial process condition corresponding to the target activity X, wherein the initial process condition comprises the unit of h-1Space velocity SV0Temperature T in degrees Celsius and pressure P in MPa;
(2) carrying out airspeed reduction test:
a) carrying out a catalytic reaction t under the initial process conditions in step (1)1Hours until the activity of the catalyst decreases by Y relative to the target activity X1％；
b) Keeping temperature T and pressure P constant, and adjusting space velocity SV0By lowering Z1% making the space velocity SV1And, at an airspeed SV1Under the condition, the activity of the catalyst is restored to the target activity X;
c) at temperature T, pressure P and space velocity SV1Continuing the catalytic reaction t under the condition2Hours until the activity of the catalyst decreases by Y relative to the target activity X2％；
d) Keeping temperature T and pressure P constant, and adjusting space velocity SV1By lowering Z2% making the space velocity SV2And is andat space velocity SV2Under the condition, the activity of the catalyst is restored to the target activity X;
e) repeating the steps c) and d) until the space velocity SV obtained after the nth reduction of the space velocity is reachednLess than space velocity SV0When the S percent is less than the S percent, the test is ended;
(3) establishing a mathematical model:
decreasing the space velocity by the ratio Z for the nth time existing at 1 st time, 2 nd time and repeating steps c) and d)1％、Z2% and Zn% is a dependent variable, and a mathematical model of airspeed change and displacement time is established by taking the corresponding displacement time t of each airspeed reduction proportion as an independent variable to obtain a mathematical equation of the airspeed change and the displacement time;
(4) determining the time and proportion of catalyst replacement:
substituting the replacement time t of the catalyst into the mathematical equation obtained in the step (3) to obtain corresponding Z%, wherein the Z% is equal to the proportion of the catalyst to be replaced at the corresponding replacement time t on the basis of the total amount of all the catalysts in the catalytic system;
said Y is1% and Y2%, and Y present by repeating steps c) and d)n% is the ratio of the 1 st, 2 nd and n th decreases in the target activity X, respectively, Y1、Y2And YnThe same or different, greater than 0 and less than 100 respectively;
the space velocity SV0Has a value corresponding to the space velocity SV of the reaction system catalyzed by the catalyst0And the lowest space velocity;
the X is more than 0% and less than or equal to 100%;
repeating the steps c) and d) at least once, wherein n is an integer greater than or equal to 3.
In a second aspect, the present invention provides a method of replacing a catalyst, the method comprising:
determining the time and proportion of catalyst replacement according to the method of the first aspect of the invention; and displacing the catalyst according to the time and the ratio.
The method for determining the catalyst replacement time and the catalyst replacement proportion has universality, and the replacement time and the catalyst replacement proportion can be determined by a simple space velocity reduction test and a mathematical model established on the basis of test data.
The method for determining the catalyst replacement time and the catalyst replacement proportion has the advantage of high accuracy.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As previously mentioned, a first aspect of the invention provides a method of determining catalyst replacement time and proportion, the method comprising:
(1) determining the target value of the catalyst:
the method comprises the steps of determining the target activity of a catalyst as X and the initial process condition corresponding to the target activity X, wherein the initial process condition comprises the unit of h-1Space velocity SV0Temperature T in degrees Celsius and pressure P in MPa;
(2) carrying out airspeed reduction test:
a) carrying out a catalytic reaction t under the initial process conditions in step (1)1Hours until the activity of the catalyst decreases by Y relative to the target activity X1％；
b) Keeping temperature T and pressure P constant, and adjusting space velocity SV0By lowering Z1% making the space velocity SV1And, at an airspeed SV1Under the condition, the activity of the catalyst is restored to the target activity X;
c) at temperature T, pressure P and space velocity SV1Continuing the catalytic reaction t under the condition2Hours until the activity of the catalyst decreases by Y relative to the target activity X2％；
d) Keeping temperature T and pressure P constant, and adjusting space velocity SV1By lowering Z2% making the space velocity SV2And, at an airspeed SV2Under the condition, the activity of the catalyst is restored to the target activity X;
e) repeating the steps c) and d) until the space velocity SV obtained after the nth reduction of the space velocity is reachednLess than space velocity SV0When the S percent is less than the S percent, the test is ended;
(3) establishing a mathematical model:
decreasing the space velocity by the ratio Z for the nth time existing at 1 st time, 2 nd time and repeating steps c) and d)1％、Z2% and Zn% is a dependent variable, and a mathematical model of airspeed change and displacement time is established by taking the corresponding displacement time t of each airspeed reduction proportion as an independent variable to obtain a mathematical equation of the airspeed change and the displacement time;
(4) determining the time and proportion of catalyst replacement:
substituting the replacement time t of the catalyst into the mathematical equation obtained in the step (3) to obtain corresponding Z%, wherein the Z% is equal to the proportion of the catalyst to be replaced at the corresponding replacement time t on the basis of the total amount of all the catalysts in the catalytic system;
said Y is1% and Y2%, and Y present by repeating steps c) and d)n% is the ratio of the 1 st, 2 nd and n th decreases in the target activity X, respectively, Y1、Y2And YnThe same or different, greater than 0 and less than 100 respectively;
the space velocity SV0Has a value corresponding to the space velocity SV of the reaction system catalyzed by the catalyst0And the lowest space velocity;
the X is more than 0% and less than or equal to 100%;
repeating the steps c) and d) at least once, wherein n is an integer greater than or equal to 3.
It should be noted that the nth time in the present invention is the number of times in the order of 1 st time and 2 nd time, and the corresponding nth time is the activity of the catalyst relative to the activity of the catalystSaid target activity X is reduced by at least Yn% and corresponding airspeed reduction ratio of Zn％。
The replacement time of the catalyst determined by the method of the invention and the replacement ratio under the corresponding replacement time have the advantages of high confidence and fitting degree (R)2) Close to 1.
For the determination of the target activity X of the catalyst, a person skilled in the art can determine the target activity X according to the factory performance of the catalyst and the characteristics of a reaction system catalyzed by the catalyst, for example, when the catalyst is an iron-based catalyst applied to the fischer-tropsch synthesis industry, the target activity X of the corresponding catalyst can be determined to be any one fixed value of 40-98% according to the operation habits in the field and the factory performance of conventional catalysts, and the fixed value is taken as an optimal activity value.
For the initial process conditions corresponding to the target activity X, the skilled person can determine a suitable initial process condition according to the reaction to be catalyzed by the catalyst and the value of the target activity X, and generally, the initial process condition is the optimal process condition for the corresponding reaction catalyzed by the catalyst. For example, when the catalyst is an iron-based catalyst applied to Fischer-Tropsch synthesis industry and performs Fischer-Tropsch synthesis reaction, the generally preferred reaction temperature T is 220-300 ℃, the preferred reaction pressure P is 1.0-5.0 MPa, and the preferred space velocity SV is0Is 8000-20000 h-1. Therefore, in order to determine the catalyst replacement time and the corresponding replacement ratio, one skilled in the art can select any one of the above-mentioned preferred reaction temperature, preferred reaction pressure and preferred space velocity, as long as the target activity of the catalyst can be made to be X determined as described above.
The significance of the selection of the optimum process conditions is primarily to enable the catalyst, for which the replacement time and the corresponding replacement proportion have been determined by the process according to the invention, to operate under the respective optimum process conditions, so that a suitable replacement proportion can be determined at different replacement times by the process according to the invention.
A certain time (t) has elapsed for the target activity of the catalyst1、t2Etc.) decrease relative to target activity X, e.g., Y1% or Y2% or YnThe determination of the specific reduction value of% can be determined by those skilled in the art according to the factory performance of the catalyst, that is, in the practical application process of the corresponding catalyst, when it is necessary to replace a part of the catalyst when the activity of the catalyst is greatly reduced, the foregoing Y can be determined according to the general reduction range1% or Y2% or Yn% of the specified values. This value is readily determinable by the person skilled in the art using the corresponding catalyst. Further, this is not a constant value, and in fact, those skilled in the art may arbitrarily select a corresponding value from 0 to 100%, as long as those skilled in the art consider that such selection is in accordance with various benefits to be considered in industrial production. Particularly preferably, said Y1、Y2And YnSame or different, greater than 0.1 and less than 50, respectively; more preferably, said Y is1、Y2And YnSame or different, greater than 0.5 and less than 20, respectively; more preferably, said Y is1、Y2And YnSame, and greater than 1 and less than 10. More preferably, said Y is1、Y2And YnSame, and greater than 1.2 and less than 5. For example, the Y1、Y2And YnMay be any one of 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 and 5.0.
Repeating steps c) and d) as described above for a number of times until the space velocity SV obtained after the nth reduction of the space velocitynLess than space velocity SV0At S%, the test is ended, while the space velocity SV is0Has a value corresponding to the space velocity SV of the reaction system catalyzed by the catalyst0And the lowest space velocity. It should be noted that there is a suitable range of process conditions corresponding to different catalysts and their corresponding application fields, for example, for the fischer-tropsch synthesis industrial iron-based catalyst, the preferred reaction temperature T is 220 to 300 ℃, the preferred reaction pressure P is 1.0 to 5.0MPa, and the preferred space velocity SV is generally 220 to 300 ℃ when performing the fischer-tropsch synthesis reaction0Is 8000-20000 h-1(ii) a Then, 8000h for this catalytic reaction system-1The space velocity of (A) is equivalent to the aforementioned lowest space velocity, because if the space velocity is lower, the yield per unit time is greatly reduced, which is not in accordance with the practical application of the process; and space velocity SV0Is equivalent to the aforementioned 20000h-1. In this example, the space velocity SV0The corresponding value of S% is 8000-20000 h-1In between, that is to say, steps c) and d) are repeated until the space velocity SV obtained after the n-th reduction of the space velocity is reachednLess than a predetermined value of 8000-20000 h-1Any value in between, the test is ended. In fact, the person skilled in the art can also predetermine the space velocity SV taking into account the actual efficiency of the industrial processnLess than 8000 to 20000h-1Which is fixed in between to determine when the trial is finished.
In step (3) of the present invention, the space velocity is reduced by the ratio Z and the n-th time existing at the 1 st time, the 2 nd time and the repetition of steps c) and d)1％、Z2% and Zn% is dependent variable, corresponding replacement time t of each airspeed reduction proportion is independent variable, and a mathematical model of airspeed and time is established to obtain a mathematical equation of airspeed change and time. The mathematical equation is a relation between Z% and time t. The time t in this equation is the time from which the reduced airspeed test begins.
Preferably, steps c) and d) are repeated at least twice, and n is an integer of 4 or more. More preferably, the steps c) and d) are repeated for 2 to 8 times, and n is an integer of 4 to 10.
Preferably, the catalyst is used in any one or more of a slurry bed reactor, a fluidized bed reactor, a moving bed reactor, a stirred tank reactor and a fixed bed reactor.
Preferably, the catalyst is any one or more than two catalysts used in fischer-tropsch synthesis reaction, methanation reaction, methanol-to-olefin reaction, water gas shift reaction, synthesis gas-to-methanol reaction, catalytic cracking reaction, hydrogenation catalytic reaction and methane reforming reaction.
As previously mentioned, a second aspect of the invention provides a method of replacing a catalyst, the method comprising:
determining the time and proportion of catalyst replacement according to the method of the first aspect of the invention; and displacing the catalyst according to the time and the ratio.
The method for determining the time and proportion of catalyst replacement according to the second aspect of the present invention is as described in the first aspect of the present invention, and the present invention will not be described herein again.
The present invention will be described in detail below by way of examples. The starting materials used in the following examples are all commercially available products unless otherwise specified.
Example 1: taking Fischer-Tropsch synthesis industrial iron catalyst (1205-N, produced by a certain catalyst factory in Zhejiang) as an example
(1) Determining the target value of the catalyst:
generally speaking, the activity X of the catalyst is required to be 60% in the industrial application of fischer-tropsch synthesis, therefore, the target activity X of the embodiment is set to be 60% according to the industrial requirement;
one of the optimum process conditions for a catalyst activity X of 60% is: space velocity SV0＝16000h-1The temperature T is 265 ℃ and the pressure P is 2.3MPa, so this condition is selected as the initial process condition;
(2) carrying out airspeed reduction test:
a) the catalytic reaction is carried out under the initial process condition in the step (1), and the catalytic reaction activity is maintained for 300h (t)1) The post-activity is reduced by 4% (Y)1％)；
b) Keeping the temperature and pressure constant, and keeping the space velocity SV0Decrease by 8% (Z)1%) to reduce the space velocity to 14720h-1(SV1) And, at an airspeed SV1Under the condition, the activity of the catalyst is restored to 60 percent of the target activity;
c) at 265 ℃, 2.3MPa and space velocity SV1The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 260h (t)2) The post-activity is reduced by 4 percent (Y)2％)；
d) Keeping the temperature and pressure constant, and keeping the space velocity SV1Decrease by 10% (Z)2%) to reduce the space velocity to 13248h-1(SV2) And, at an airspeed SV2Under the condition, the activity of the catalyst is restored to 60 percent of the target activity;
e) at 265 ℃, 2.3MPa and space velocity SV2The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 210h (t)3) The post-activity is reduced by 4 percent (Y)3％)；
f) Keeping the temperature and pressure constant, and keeping the space velocity SV2Decrease by 13% (Z)3%) to make the space velocity drop to 11526h-1(SV3) And, at an airspeed SV3Under the condition, the activity of the catalyst is restored to 60 percent of the target activity;
g) at 265 ℃, 2.3MPa and space velocity SV3The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 130h (t)4) The post-activity is reduced by 4 percent (Y)4％)；
h) Keeping the temperature and pressure constant, and keeping the space velocity SV3Decrease by 17% (Z)4%) to reduce the space velocity to 9566h-1(SV4) And, at an airspeed SV4Under the condition, the activity of the catalyst is restored to 60 percent of the target activity;
i) at 265 ℃, 2.3MPa and space velocity SV4The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 80h (t)5) The post-activity is reduced by 4 percent (Y)5％)；
j) Keeping the temperature and pressure constant, and keeping the space velocity SV4Decrease by 20% (Z)5%) to reduce the space velocity to 7653h-1(SV5) And is andat space velocity SV5Under the condition, the activity of the catalyst is restored to 60 percent of the target activity; at this time, the SV5Is SV only048% (S%) of the test, the test is ended.
(3) Establishing a mathematical model:
decreasing the space velocity by a reduction ratio Z for the 3 rd, 4 th and 5 th times existing in the 1 st, 2 nd times and repeating steps c) and d)1％、Z2％、Z3％、Z4% and Z5% is a dependent variable, and a mathematical model of airspeed change and displacement time is established by taking the corresponding displacement time t of each airspeed reduction ratio as an independent variable, so as to obtain a mathematical equation of the airspeed change and the displacement time: z% ═ 1.87 × (t/1000)3-2.74×(t/1000)2+1.65 (t/1000) -0.218, degree of fitting R2＝0.9998。
(4) Determining the time and proportion of catalyst replacement:
substituting the replacement time t of the catalyst into the mathematical equation obtained in the step (3) to obtain corresponding Z%, wherein the Z% is equal to the proportion of the catalyst to be replaced at the corresponding replacement time t on the basis of the total amount of all the catalysts in the catalytic system; for example, the catalyst activity decreased at 320h, the catalyst was replaced, and t ═ 320 was substituted into the equation to obtain Z ═ 9.1%, i.e., 9.1% of the catalyst needed to be replaced at 320 h.
Example 2: take industrial catalyst for preparing olefin from methanol (MTO-6, produced by Shandong catalyst factory) as an example
(1) Determining the target value of the catalyst:
the activity X of the methanol to olefin catalyst is generally 82 to 92%, and therefore, the target activity X of the present embodiment is set to 87% according to the industrial requirements;
one of the optimum process conditions for a catalyst activity X of 87% is: space velocity SV0＝3.0h-1The temperature T is 470 ℃ and the pressure P is 0.1MPa, so this condition is selected as the initial process condition;
(2) carrying out airspeed reduction test:
a) carrying out a catalytic reaction under the initial process conditions of step (1)The activity should be maintained for 40h (t)1) The post-activity is reduced by 2% (Y)1％)；
b) Keeping the temperature and pressure constant, and keeping the space velocity SV0Decrease by 2.1% (Z)1%) to reduce the space velocity to 2.94h-1(SV1) And, at an airspeed SV1Under the condition, the activity of the catalyst is restored to 87 percent of target activity;
c) at 470 ℃, 0.1MPa and space velocity SV1The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 52h (t)2) The post-activity is reduced by 2 percent (Y)2％)；
d) Keeping the temperature and pressure constant, and keeping the space velocity SV1Decrease by 2.8% (Z)2%) to reduce the space velocity to 2.85h-1(SV2) And, at an airspeed SV2Under the condition, the activity of the catalyst is restored to 87 percent of target activity;
e) at 470 ℃, 0.1MPa and space velocity SV2The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 66h (t)3) The post-activity is reduced by 2 percent (Y)3％)；
f) Keeping the temperature and pressure constant, and keeping the space velocity SV2Decrease by 4.2% (Z)3%) to reduce the space velocity to 2.73h-1(SV3) And, at an airspeed SV3Under the condition, the activity of the catalyst is restored to 87 percent of target activity;
g) at 470 ℃, 0.1MPa and space velocity SV3The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 80h (t)4) The post-activity is reduced by 2 percent (Y)4％)；
h) Keeping the temperature and pressure constant, and keeping the space velocity SV3Decrease by 5.8% (Z)4%) to reduce the space velocity to 2.58h-1(SV4) And, at an airspeed SV4Under the condition, the activity of the catalyst is restored to 87 percent of target activity;
i) at 470 ℃, 0.1MPa and space velocity SV4The catalytic reaction is continued under the condition that the catalytic reaction activity is maintained for 100h (t)5) The post-activity is reduced by 2 percent (Y)5％)；
j) Keeping the temperature and pressure constant, and keeping the space velocity SV4Decrease by 7.2% (Z)5%) to reduce the space velocity to 2.39h-1(SV5) And, at an airspeed SV5Under the condition, the activity of the catalyst is restored to 87 percent of target activity; at this time, the SV5Is SV only080% (S%) of the test, the test was ended.
(3) Establishing a mathematical model:
decreasing the space velocity by a reduction ratio Z for the 3 rd, 4 th and 5 th times existing in the 1 st, 2 nd times and repeating steps c) and d)1％、Z2％、Z3％、Z4% and Z5% is a dependent variable, and a mathematical model of airspeed change and displacement time is established by taking the corresponding displacement time t of each airspeed reduction ratio as an independent variable, so as to obtain a mathematical equation of the airspeed change and the displacement time: z% -0.00062 Xt-0.0066 degree of fitting R2＝0.9990。
(4) Determining the time and proportion of catalyst replacement:
substituting the replacement time t of the catalyst into the mathematical equation obtained in the step (3) to obtain corresponding Z%, wherein the Z% is equal to the proportion of the catalyst to be replaced at the corresponding replacement time t on the basis of the total amount of all the catalysts in the catalytic system; for example, the catalyst activity decreased at 100h, the catalyst was replaced, and the equation was substituted with t equal to 100 to obtain Z% equal to 5.54%, i.e., 5.54% of the catalyst needed to be replaced at 100 h.
The method provided by the invention has the advantages of universality, and the complex tests of 'unloading' and 'adding' of the catalyst are not needed by the method for determining the catalyst replacement time and the catalyst replacement proportion by combining the test and the model, but the method is a method for establishing a mathematical model on the basis of test data through a simple space velocity reduction test, so that the accuracy of the model is ensured, and the model does not need to be verified again.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method of determining catalyst replacement time and proportion, the method comprising:
(1) determining the target value of the catalyst:
the method comprises the steps of determining the target activity of a catalyst as X and the initial process condition corresponding to the target activity X, wherein the initial process condition comprises the unit of h-1Space velocity SV0Temperature T in degrees Celsius and pressure P in MPa;
(2) carrying out airspeed reduction test:
a) carrying out a catalytic reaction t under the initial process conditions in step (1)1Hours until the activity of the catalyst decreases by Y relative to the target activity X1％；
b) Keeping temperature T and pressure P constant, and adjusting space velocity SV0By lowering Z1% making the space velocity SV1And, at an airspeed SV1Under the condition, the activity of the catalyst is restored to the target activity X;
c) at temperature T, pressure P and space velocity SV1Continuing the catalytic reaction t under the condition2Hours until the activity of the catalyst decreases by Y relative to the target activity X2％；
d) Keeping temperature T and pressure P constant, and adjusting space velocity SV1By lowering Z2% making the space velocity SV2And, at an airspeed SV2Under the condition, the activity of the catalyst is restored to the target activity X;
e) repeating the steps c) and d) until the space velocity SV obtained after the nth reduction of the space velocity is reachednLess than space velocity SV0When the S percent is less than the S percent, the test is ended;
(3) establishing a mathematical model:
decreasing the space velocity by the ratio Z for the nth time existing at 1 st time, 2 nd time and repeating steps c) and d)1％、Z2% and Zn% is a dependent variable, and a mathematical model of airspeed change and displacement time is established by taking the corresponding displacement time t of each airspeed reduction proportion as an independent variable to obtain a mathematical equation of the airspeed change and the displacement time;
(4) determining the time and proportion of catalyst replacement:
substituting the replacement time t of the catalyst into the mathematical equation obtained in the step (3) to obtain corresponding Z%, wherein the Z% is equal to the proportion of the catalyst to be replaced at the corresponding replacement time t on the basis of the total amount of all the catalysts in the catalytic system;
said Y is1% and Y2%, and Y present by repeating steps c) and d)n% is the ratio of the 1 st, 2 nd and n th decreases in the target activity X, respectively, Y1、Y2And YnThe same or different, greater than 0 and less than 100 respectively;
the space velocity SV0Has a value corresponding to the space velocity SV of the reaction system catalyzed by the catalyst0And the lowest space velocity;
the X is more than 0% and less than or equal to 100%;
repeating the steps c) and d) at least once, wherein n is an integer greater than or equal to 3.
2. The method of claim 1, wherein steps c) and d) are repeated at least twice, and n is an integer greater than or equal to 4.
3. The method according to claim 2, wherein the steps c) and d) are repeated 2 to 8 times, and n is an integer of 4 to 10.
4. The method of claim 1, wherein said Y is1、Y2And YnEqual to or different from greater than 0.1 and less than 50, respectively.
5. The method of claim 4, wherein said Y1、Y2And YnEqual to or different from greater than 0.5 and less than 20, respectively.
6. The method of claim 5, wherein said Y1、Y2And YnSame, and greater than 1 and less than 10.
7. The method of claim 6, wherein said Y1、Y2And YnSame, and greater than 1.2 and less than 5.
8. The method according to any one of claims 1 to 7, wherein the catalyst is a catalyst for any one or two or more of a slurry bed reactor, a fluidized bed reactor, a moving bed reactor, a stirred tank reactor and a fixed bed reactor.
9. The method according to claim 8, wherein the catalyst is any one or more of a catalyst used in a Fischer-Tropsch synthesis reaction, a methanation reaction, a methanol-to-olefin reaction, a water gas shift reaction, a syngas-to-methanol reaction, a catalytic cracking reaction, a hydrocatalytic reaction, and a methane reforming reaction.
10. A method of replacing a catalyst, the method comprising:
determining the time and proportion of catalyst replacement according to the method of any one of claims 1-9; and displacing the catalyst according to the time and the ratio.
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