Method for estimating thickness of coking layer of dome of settler of catalytic cracking unit

Abstract

The invention relates to a method and equipment for estimating the thickness of a coking layer of a settler dome of a catalytic cracking unit and a storage medium, and the method comprises the following steps: simultaneously establishing a coking layer heat transfer rate calculation formula and a reference layer heat transfer rate calculation formula to obtain a coking thickness estimation formula, the coking thickness estimation formula does not have a heat transfer rate variable of heat in a coking layer and a heat transfer rate variable of heat in a reference layer, and the estimation formula is used for expressing a calculation mode of the thickness variable of the coking layer through a temperature difference expression between two sides of the coking layer and a temperature difference expression between two sides of the reference layer. Therefore, when the thickness of the coking layer is estimated in production, the actually-measured temperature difference between the two sides of the coking layer and the actually-measured temperature difference between the two sides of the reference layer can be detected in real time, and the coking thickness estimation value is calculated according to the actually-measured temperature difference between the two sides of the coking layer and the actually-measured temperature difference between the two sides of the reference layer by utilizing a coking thickness estimation formula. And the method does not need to depend on historical data set by the settler.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic cracking, and in particular to a method for estimating the thickness of a coking layer on a dome of a settler of a catalytic cracking device. Background Art

[0002] Catalytic cracking unit is the main production unit of gasoline in my country, producing about 70% of the total gasoline, and is the core unit of oil refining enterprises. Catalytic cracking unit uses atmospheric and vacuum wax oil, residual oil, coking wax oil, and heavy oil after hydrogenation of residual oil as raw materials. Under the action of catalyst and high temperature, it reacts to produce products such as liquefied gas, gasoline, diesel, oil slurry and coke.

[0003] The settler is a device that separates the reaction oil and gas from the catalyst. The separated catalyst enters the regenerator for charring and regeneration, while the reaction oil and gas go to the fractionation tower through the large oil and gas pipeline for further separation. Whether the settler can work properly directly affects the pressure balance and normal production of the reaction regeneration system.

[0004] Since high-temperature oil and gas contain components that are prone to coking, they will carry the catalyst to form coke in multiple parts of the settler, such as the cyclone separator, the inner wall of the settler, the dome, etc., especially in parts with sudden changes in the structure. The dome of the settler is one of the most serious parts of coking. The hazards caused by coking at the dome are mainly:

[0005] (1) The normal oil and gas flow channels are blocked.

[0006] (2) The coke may fall off, increasing the safety risk of the equipment.

[0007] (3) In severe cases, it may cause unplanned shutdown of the catalytic cracking unit.

[0008] Therefore, the real-time evaluation of coking on the settler dome is of great significance. The real-time evaluation of coking on the settler dome is helpful in judging the extent of coking and in suggesting the appropriate time for shutdown and maintenance.

[0009] Since the mechanism of coking is very complex, it is very difficult to analyze the mechanism. In addition, since coking is invisible and intangible, and there is a lack of detection methods, it is also very difficult to evaluate and analyze coking in real time.

[0010] At present, the real-time evaluation of coking thickness uses fluid mechanics to analyze the experimental device and establishes a model for estimating the coking amount of the settler. However, this model is a method for calculating the coking amount by forward deduction from the mechanism of coking formation. When judging the current coking degree, this method requires historical data of all relevant factors since the start-up of the catalytic cracking unit. Once the intermediate data is missing, the calculation cannot proceed smoothly. Summary of the invention

[0011] The present disclosure provides a method, device, storage medium and computer program for estimating the thickness of the coking layer on the dome of a settler of a catalytic cracking unit, so as to estimate the coking degree in real time without relying on historical data since the start-up of the settler.

[0012] In a first aspect, the present disclosure provides a method for estimating the thickness of a coking layer on a dome of a settler of a catalytic cracking unit, comprising:

[0013] Obtaining a measured temperature difference between two sides of the coking layer and a measured temperature difference between two sides of a reference layer of a settler dome;

[0014] Based on the coking thickness estimation formula, the estimated value of the coking layer thickness is calculated according to the measured temperature difference on both sides of the coking layer and the measured temperature difference on both sides of the reference layer; wherein,

[0015] The coking thickness estimation formula is obtained by combining the heat transfer rate calculation formula of the coking layer and the heat transfer rate calculation formula of the reference layer based on the principle that the heat transfer rate under the steady-state production state is equal. The heat transfer rate calculation formula of the coking layer is obtained by correlating the temperature difference expression between the two sides of the coking layer, the thickness variable of the coking layer and the heat transfer rate variable of the coking layer based on Fourier's law. The heat transfer rate calculation formula of the reference layer is obtained by correlating the temperature difference expression between the two sides of the reference layer and the heat transfer rate variable of the reference layer based on Fourier's law.

[0016] In some embodiments, the step of obtaining the measured temperature difference between the two sides of the coking layer includes:

[0017] obtaining the bulk temperature of the fluid in the settler;

[0018] Obtain the inner wall temperature of the dome of the settler;

[0019] The difference between the bulk temperature of the fluid in the settler and the inner wall temperature of the dome of the settler is calculated to obtain the measured temperature difference between the two sides of the coking layer.

[0020] In some embodiments, the step of obtaining the measured temperature difference between two sides of the reference layer includes:

[0021] Obtain the inner wall temperature of the dome of the settler;

[0022] Obtain the outer wall temperature of the settler;

[0023] The difference between the inner wall temperature of the dome of the settler and the outer wall temperature of the settler is calculated to obtain the measured temperature difference between the two sides of the reference layer.

[0024] In some embodiments, the coking thickness estimation formula is as follows:

[0025]

[0026] Among them, S1 is the estimated value of the coking layer thickness, T w1 and T w2 is the temperature on both sides of the coking layer, T v1 and T v2 is the temperature on both sides of the reference layer, and k is the coefficient.

[0027] In some embodiments, the coking thickness estimation formula is as follows:

[0028]

[0029] Among them, S1 is the estimated value of the coking layer thickness, T w1 is the bulk temperature of the fluid in the settler, T w2 is the inner wall temperature of the dome of the settler, T w3 is the outer wall temperature of the insulation layer of the dome of the settler, and k is the coefficient.

[0030] In some embodiments, the estimating method further comprises:

[0031] Obtaining a coke thickness estimation value calculated using a coke thickness estimation formula within a preset time period before coke cleaning and an estimated coke thickness value within a preset time period after coke cleaning;

[0032] Detecting changes in the estimated value of coke thickness within a preset period of time before defocusing and changes in the estimated value of coke thickness within a preset period of time after defocusing;

[0033] When the estimated coke thickness increases to a first coke thickness value within a preset period before defocusing and starts to increase with a second coke thickness value within a preset period after defocusing, a result that meets the consistency requirements is output, wherein the first coke thickness value is greater than the second coke thickness value.

[0034] In some embodiments, the estimating method further comprises:

[0035] Obtaining the values ​​of measurable production parameters;

[0036] Calculate the correlation between the numerical value of the measurable production parameter and the estimated value of the coke thickness to obtain a correlation coefficient;

[0037] Check whether the absolute value of the correlation coefficient is less than or equal to the correlation threshold;

[0038] When the absolute value of the correlation coefficient is less than or equal to the correlation threshold, a result that meets the coking exclusivity is output.

[0039] In some embodiments, the estimating method further comprises:

[0040] Obtaining the estimated value of coking thickness corresponding to a preset discrete time point within the operation period, where the operation period is the period between two adjacent coking cleaning operations;

[0041] Calculate the interval between each preset discrete time point and the end of the last coking cleaning work to obtain the operation time of each preset discrete time point;

[0042] Detect whether the estimated coking thickness corresponding to the preset discrete time point is positively correlated with the operation time;

[0043] When the estimated coking thickness corresponding to the preset discrete time point is positively correlated with the operation time, the output is a significant result.

[0044] In a second aspect, the present disclosure provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above aspect.

[0045] In a third aspect, the present disclosure provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method described in the above aspects when executed by a processor.

[0046] The present disclosure provides a method, device and storage medium for estimating the thickness of the coking layer of the dome of a settler of a catalytic cracking unit. When heat passes through the coking layer, the heat is transferred from one side of the coking layer to the other side of the coking layer, and the heat is reduced. There is a temperature difference between the two sides of the coking layer. According to Fourier's law, a calculation formula for the heat transfer rate of the heat when passing through the coking layer, that is, a calculation formula for the heat transfer rate of the coking layer, can be constructed. The calculation formula for the heat transfer rate of the coking layer is used to calculate the heat transfer rate variable of the coking layer according to the temperature difference expression between the two sides of the coking layer and the thickness variable of the coking layer. The reference layer is a structural layer that needs to be measured in advance in the dome of the settler, and can be a structural layer at a predetermined position of the body of the settler. The reference layer is selected based on the principle of measuring the parameters involved in the heat transfer rate calculation formula of the reference layer, so as to determine the measurement data corresponding to more variables in the heat transfer rate calculation formula of the reference layer during estimation, and reduce the manual estimation of the variables. When the production is stable, the assumption that the dome is barely loaded with a large flat plate is assumed, and the heat flows through the coking layer and the reference layer in turn, and the heat transfer rate is equal. According to Fourier's law, a calculation formula for the heat transfer rate when heat passes through the reference layer, namely, the reference layer heat transfer rate calculation formula, is constructed. The reference layer heat transfer rate calculation formula is used to calculate the heat transfer rate variable of the coking layer.

[0047] When the settler is in a steady-state state of production, the heat transfer rate variable of the heat in the reference layer is equal to the heat transfer rate variable of the heat in the coking layer. Therefore, the heat transfer rate variable of the reference layer and the heat transfer rate variable of the coking layer can be eliminated by the elimination method, and the heat transfer rate calculation formula of the coking layer and the heat transfer rate calculation formula of the reference layer are combined to obtain the coking thickness estimation formula. The coking thickness estimation formula does not have the heat transfer rate variable of the heat in the coking layer and the heat transfer rate variable of the heat in the reference layer. The estimation formula is used to express the calculation method of the coking layer thickness variable through the temperature difference expression between the two sides of the coking layer and the temperature difference expression between the two sides of the reference layer. Therefore, when estimating the thickness of the coking layer in production, the measured temperature difference between the two sides of the coking layer and the measured temperature difference between the two sides of the reference layer can be detected in real time. The coking thickness estimation formula is used to calculate the estimated value of the coking thickness according to the measured temperature difference between the two sides of the coking layer and the measured temperature difference between the two sides of the reference layer, without relying on historical data since the start of the settler. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0049] Figure 1 A schematic flow chart of a method for estimating the thickness of a coking layer on a dome of a settler of a catalytic cracking unit provided in an embodiment of the present disclosure;

[0050] Figure 2 A schematic diagram of heat transfer at the dome of a settler provided in an embodiment of the present disclosure;

[0051] Figure 3 A schematic diagram of a curve showing the coking index versus production time provided in an embodiment of the present disclosure.

[0052] In the drawings, the same reference numerals are used for the same components, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, and to fully understand and implement how the present disclosure applies technical means to solve technical problems and achieve the corresponding technical effects, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only embodiments of a part of the present disclosure, not all of the embodiments. The embodiments of the present disclosure and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the scope of protection of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present disclosure.

[0054] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0055] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0056] After consulting the literature and patents, the coking of the settler of the catalytic cracking unit is concentrated in the following aspects:

[0057] (1) Qualitative analysis and optimization of the hazards of coking, the nature of coking, and general preventive measures do not involve real-time assessment of the degree of coking.

[0058] (2) The fluid mechanics analysis and experiments on the coking formation mechanism do not involve real-time evaluation of the degree of coking.

[0059] (3) From the perspective of coking principle, the coking amount is calculated based on indicators such as gasification rate, condensation rate, and coking rate. This is a positive calculation method that is used to determine the current coking degree, but it requires historical data of all relevant factors since the start of operation.

[0060] Embodiment 1

[0061] Figure 1 The present invention provides a schematic flow diagram of a method for estimating the thickness of the coking layer on the dome of a catalytic cracking unit settler. Figure 1 As shown, a method for estimating the thickness of the coking layer on the dome of a catalytic cracking unit settler comprises:

[0062] Step 110, obtaining the measured temperature difference between the two sides of the coking layer and the measured temperature difference between the two sides of the reference layer of the dome of the settler.

[0063] In this embodiment, for the dome of the settler, a coking layer is usually formed on the inner wall of the dome of the settler, and the coking layer is in contact with the inner wall of the settler. Both sides of the coking layer include a first side facing the material in the settler and a second side in contact with the inner wall of the settler. The heat in the settler is first transferred to the first side of the coking layer, and the heat is transferred inside the coking layer, from the first side of the coking layer to the second side of the coking layer. The reference layer is selected based on the principle of measuring the temperature on both sides of the reference layer. For example, it can be the dome layer of the settler, then the temperature on both sides of the reference layer includes the inner wall temperature of the dome of the settler and the outer wall temperature of the insulation layer of the dome of the settler. Heat is transferred from the inner wall of the dome of the settler to the outer wall of the dome of the settler.

[0064] In one embodiment, the step of obtaining the measured temperature difference between the two sides of the coking layer includes:

[0065] obtaining the bulk temperature of the fluid in the settler;

[0066] Obtain the inner wall temperature of the dome of the settler;

[0067] The difference between the bulk temperature of the fluid in the settler and the inner wall temperature of the dome of the settler is calculated to obtain the measured temperature difference between the two sides of the coking layer.

[0068] In practical applications, the main body temperature of the fluid in the settler is measured as the temperature of the coking layer on the side facing the material in the settler. The coking layer is usually attached to the inner wall of the settler, especially the inner wall of the dome of the settler, and the temperature of the coking layer on the side in contact with the inner wall of the dome of the settler is usually the inner wall temperature of the dome of the settler. Therefore, the measured temperature difference between the two sides of the coking layer can be obtained by subtracting the inner wall temperature of the dome of the settler from the main body temperature of the fluid in the settler. The inner wall temperature of the dome of the settler is the temperature at the contact point between the coking layer and the inner wall of the dome of the settler.

[0069] In one embodiment, the step of obtaining the measured temperature difference between two sides of the reference layer includes:

[0070] Obtain the inner wall temperature of the dome of the settler;

[0071] Obtain the outer wall temperature of the settler;

[0072] The difference between the inner wall temperature of the dome of the settler and the outer wall temperature of the settler is calculated to obtain the measured temperature difference between the two sides of the reference layer.

[0073] In this embodiment, the reference layer is the equipment and insulation layer of the settler, that is, the main body layer forming the outline of the settler, and the thickness of the reference layer is the thickness of the outline of the settler. The inner wall temperature of the dome of the settler can be the temperature of the wall surface of the dome of the settler facing the fluid, and the outer wall temperature of the settler can be the outer wall temperature of the insulation layer of the dome of the settler. The measured temperature difference between the two sides of the reference layer can be obtained by subtracting the outer wall temperature of the settler from the inner wall temperature of the dome of the settler.

[0074] Step 120, based on the coking thickness estimation formula, according to the measured temperature difference on both sides of the coking layer and the measured temperature difference on both sides of the reference layer, calculate the estimated value of the coking layer thickness; wherein, the coking thickness estimation formula is obtained by combining the coking layer heat transfer rate calculation formula and the reference layer heat transfer rate calculation formula based on the principle that the heat transfer rate is equal under the production steady state, the coking layer heat transfer rate calculation formula is obtained by associating the temperature difference expression between the two sides of the coking layer, the thickness variable of the coking layer and the heat transfer rate variable of the coking layer based on Fourier's law, and the reference layer heat transfer rate calculation formula is obtained by associating the temperature difference expression between the two sides of the reference layer and the heat transfer rate variable of the reference layer based on Fourier's law.

[0075] In this embodiment, when heat is transferred in the coking layer, the temperature gradually decreases in the coking layer along the direction of heat transfer, and there is a temperature difference between the two sides of the coking layer. Based on Fourier's law, a formula for calculating the heat transfer rate variable of the coking layer is constructed according to the temperature difference expression between the two sides of the coking layer and the thickness variable of the coking layer, so that the temperature difference expression between the two sides of the coking layer, the thickness variable of the coking layer and the heat transfer rate variable of the coking layer are associated, and the heat transfer rate calculation formula of the coking layer is obtained. When heat is transferred in the reference layer, the temperature gradually decreases in the reference layer along the direction of heat transfer, and there is a temperature difference between the two sides of the reference layer. Based on Fourier's law, a formula for calculating the heat transfer rate variable of the reference layer is constructed according to the temperature difference expression between the two sides of the reference layer, so that the temperature difference expression between the two sides of the reference layer and the heat transfer rate variable of the reference layer are associated, and the heat transfer rate calculation formula of the reference layer is obtained.

[0076] In this embodiment, when the settler is in a steady-state state, the heat transfer rate variable of the coking layer is equal to the heat transfer rate variable of the reference layer. Therefore, the constructed heat transfer rate calculation formula of the coking layer and the heat transfer rate calculation formula of the reference layer can be linked, and the heat transfer rate variable of the coking layer and the heat transfer rate variable of the reference layer are eliminated by the elimination method to obtain the coking thickness estimation formula. The coking thickness estimation formula associates the temperature difference expression between the two sides of the coking layer, the thickness variable of the coking layer and the temperature difference expression between the two sides of the reference layer. The temperature difference expression between the two sides of the coking layer is used as a variable of a value to be calculated in subsequent applications, and the temperature difference expression between the two sides of the coking layer and the temperature difference expression between the two sides of the reference layer are used as variables of known values ​​in subsequent applications. During the application process, the measured temperatures on both sides of the coking layer are measured, the two measured temperatures are subtracted to obtain the measured temperature difference on both sides of the coking layer, and the measured temperature difference on both sides of the coking layer is substituted into the temperature difference expression between the two sides of the coking layer in the coking thickness estimation formula; the measured temperatures on both sides of the reference layer are measured, the two measured temperatures are subtracted to obtain the measured temperature difference on both sides of the reference layer, and the measured temperature difference on both sides of the reference layer is substituted into the temperature difference expression between the two sides of the reference layer in the coking thickness estimation formula, thereby calculating the estimated value of the coking layer thickness.

[0077] In one embodiment, the coking thickness estimation formula is as follows:

[0078]

[0079] Among them, S1 is the estimated value of the coking layer thickness, T w1 and T w2 is the temperature on both sides of the coking layer, T v1 and T v2 is the temperature on both sides of the reference layer, and k is the coefficient.

[0080] In this embodiment, heat is transferred from the first side of the coking layer into the interior of the coking layer, and the heat inside the coking layer is transferred from the second side of the coking layer to the exterior of the coking layer. w1 is the temperature of the first side of the coking layer, T w2 is the temperature of the second side of the coking layer. Heat is transferred from the first side of the reference layer into the interior of the reference layer, and the heat inside the reference layer is transferred from the second side of the reference layer to the exterior of the reference layer, T v1 is the temperature of the first side of the reference layer, T v2 is the temperature of the second side of the reference layer. The coefficient k can be an empirical value set manually or based on Where λ1 is the thermal conductivity of the coking layer, λ2 is the thermal conductivity of the reference layer, and S2 is the thickness of the reference layer. The reference layer is the dome layer of the settler, which includes a dome material layer and a thermal insulation layer. The thermal conductivity of the reference layer is the combined thermal conductivity of the dome material layer and the thermal insulation layer. It should be understood that when the second side of the coking layer and the first side of the reference layer are in contact or coplanar relationship, the temperature T of the first side of the reference layer is v1 The temperature T of the second side of the coking layer w2 It can be the temperature at the same position, so the temperature T of the first side of the reference layer is v1 Equivalent to the temperature T of the second side of the coking layer w2 .

[0081] See also Figure 2 In one embodiment, the coking thickness estimation formula is as follows:

[0082]

[0083] Among them, S1 is the estimated value of the coking layer thickness, T w1 is the bulk temperature of the fluid in the settler, T w2 is the inner wall temperature of the dome of the settler, T w3 is the outer wall temperature of the dome of the settler, and k is the coefficient.

[0084] In this embodiment, in order to facilitate the measurement of the temperature required for the coking thickness estimation formula, the coking layer is the coking attached to the dome of the settler, and the reference layer is the dome layer of the settler. At this time, the coking layer is in contact with the reference layer, and the second side of the coking layer and the first side of the reference layer are both the inner wall of the dome of the settler. Heat flows through the coking layer and the reference layer in turn. The first side of the coking layer faces the material, and the main body temperature T of the fluid in the settler can be used. w1 The temperature of the first side of the coking layer is taken as the temperature of the second side of the coking layer. The second side of the coking layer contacts the inner wall of the dome. A temperature sensor is arranged on the inner wall of the dome to detect the temperature of the inner wall of the dome as the temperature of the second side of the coking layer. Therefore, the main body temperature T of the fluid in the settler is taken as w1 Subtract the inner wall temperature T of the dome of the settler w2 , we get the temperature difference expression T between the two sides of the coking layer w1 -T w2 The first side of the reference layer is the inner wall of the dome of the settler, and the inner wall temperature of the dome of the settler is T w2 The temperature of the first side of the reference layer is used as the temperature of the outer wall of the dome. The temperature of the outer wall of the dome of the settler is used as the temperature of the second side of the reference layer. The coefficient k can be an empirical value set by humans or can be based on where λ1 is the thermal conductivity of the coking layer, λ2 is the thermal conductivity of the reference layer, and S2 is the thickness of the reference layer. w3 Usually 60℃ is suitable.

[0085] See also Figure 3 In one embodiment, the method further comprises:

[0086] Obtaining a coke thickness estimation value calculated using the coke thickness estimation formula within a preset time period before coke cleaning and a coke thickness estimation value within a preset time period after coke cleaning;

[0087] Detecting changes in the estimated value of coke thickness within a preset period of time before defocusing and changes in the estimated value of coke thickness within a preset period of time after defocusing;

[0088] When the estimated coke thickness increases to a first coke thickness value within a preset period before defocusing and starts to increase with a second coke thickness value within a preset period after defocusing, a result that meets the consistency requirements is output, wherein the first coke thickness value is greater than the second coke thickness value.

[0089] In this embodiment, the coke cleaning operation cleans the coke in the settler, so the thickness of the coke layer will be reduced. The pre-coke cleaning preset period is a preset period before the start time of the coke cleaning operation, for example, within one week before the start time of the coke cleaning operation; the pre-coke cleaning preset period is a preset period after the end time of the coke cleaning operation, for example, within one week after the end time of the coke cleaning operation. The coke thickness estimation formula is used to calculate the estimated value of the coke thickness in the pre-coke cleaning preset period and the estimated value of the coke thickness in the pre-coke cleaning preset period. Detect the change of the estimated value of coking thickness in the preset time period before decoking and detect the change of the estimated value of coking thickness in the preset time period after decoking. When it is detected that the estimated value of coking thickness increases to the first coking thickness value in the preset time period before decoking and starts to increase with the second coking thickness value in the preset time period after decoking, and the first coking thickness value is greater than the second coking thickness value, it means that in the preset time period before decoking, as the material in the settler reacts, the thickness of the coking layer increases to the first coking thickness value. When the decoking work is being carried out, the thickness of the coking layer gradually decreases until the end of the decoking work, when the thickness of the coking layer decreases to the second coking thickness value. In the preset time period after decoking, as the material in the settler reacts, the thickness of the coking layer gradually increases from the second coking thickness value. This shows that the estimated value of the coking layer thickness calculated by the coking thickness estimation formula is in line with the actual situation. In the preset time period before coking and the preset time period after coking, the thickness of the coking layer increases with the reaction of materials in the settler, and the estimated value of the coking thickness at the beginning of the preset time period after coking is smaller than the estimated value of the coking thickness at the end of the preset time period before coking.

[0090] In one embodiment, the method further comprises:

[0091] Obtaining the values ​​of measurable production parameters;

[0092] Calculating the correlation between the numerical value of the measurable production parameter and the estimated value of the coking thickness to obtain a correlation coefficient;

[0093] Detecting whether the absolute value of the correlation coefficient is less than or equal to a correlation threshold;

[0094] When the absolute value of the correlation coefficient is less than or equal to the correlation threshold, the output is consistent with the result of coking exclusivity. In this embodiment, the measurable production parameters are, for example, the amount of atomizing steam, the pressure of the settler, the reaction feed amount, the outlet temperature of the riser, and the position of the regeneration slide valve. The Pearson correlation calculation formula is used to calculate the correlation between the numerical value of the measurable production parameter and the estimated value of the coking thickness to obtain the correlation coefficient. The larger the absolute value of the correlation coefficient, the greater the degree of correlation between the numerical value of the measurable production parameter and the estimated value of the coking thickness. It is detected whether the absolute value of the correlation coefficient is less than or equal to the correlation threshold, and the correlation threshold is used to measure whether the numerical value of the controllable production parameter and the estimated value of the coking thickness are related. When the absolute value of the correlation coefficient is less than or equal to the correlation threshold, it means that the controllable production parameter has little effect on the coking, and the estimated value of the coking thickness calculated by the coking thickness estimation formula is caused by the actual change in the thickness of the coking layer, and the estimated value of the coking thickness is not caused by the change in the measurable production parameter.

[0095] See also Figure 3 In one embodiment, the method further comprises:

[0096] Obtaining an estimated value of coking thickness corresponding to a preset discrete time point within an operation period, wherein the operation period is a period between two adjacent coking cleaning operations;

[0097] Calculate the interval between each of the preset discrete time points and the end of the last coking cleaning work to obtain the operation time of each of the preset discrete time points;

[0098] Detecting whether the estimated value of coking thickness corresponding to the preset discrete time point is positively correlated with the operation duration;

[0099] When the estimated coking thickness corresponding to the preset discrete time point is positively correlated with the operation duration, a significant result is output.

[0100] In this embodiment, affected by factors other than coking, the coke thickness estimation value calculated by the coke thickness estimation formula may have deviations, resulting in noise in the coke thickness estimation value. In order to test whether the influence of coking on the coke thickness estimation value is significant enough, the overall trend of the coke thickness estimation value in each operating period is analyzed. The operating period is the period between two adjacent coke cleaning operations. In principle, during the operating period, the coke thickness estimation value is mainly affected by coking. Therefore, as the material in the settler reacts, the coke thickness estimation value calculated by the coke thickness estimation formula should gradually increase. However, affected by other factors, such as measurement errors in temperature measurement, the coke thickness estimation value calculated at the next moment may decrease or mutate relative to the coke thickness estimation value calculated at the previous moment. In order to detect the degree of influence of other factors, a preset discrete time point is determined during the operating period, and there are multiple preset discrete time points, the time points are separated, and there is a preset duration between two adjacent time points. Each preset discrete time point is distributed on the time axis of the operation period, and the interval between each preset discrete time point and the end of the last coking cleaning work is calculated, that is, the time period between the preset discrete time point and the end of the last coking cleaning work is calculated to obtain the operation time of each preset discrete time point. The longer the operation time, the longer the time from the current preset discrete time point to the end of the last coking cleaning work, and the thickness of the coking layer is usually greater. Detect whether the coking thickness estimate corresponding to the preset discrete time point and the operation time are greater than the preset correlation coefficient threshold. The preset correlation coefficient threshold is a positive number, which is used to measure whether the coking thickness estimate and the operation time have reached a positive correlation. When the coking thickness estimate and the operation time are greater than the preset correlation coefficient threshold, it means that the positive correlation between the coking thickness estimate and the operation time is large. The main factor affecting the change of the coking thickness estimate is the material reaction in the settler. The coking thickness estimate increases with the increase of the time of the material reaction in the settler, and the coking has a significant effect on the coking thickness estimate.

[0101] In this embodiment, the density of the distribution of the preset discrete time points and the preset correlation coefficient threshold affect the accuracy of the significance detection. The denser the distribution of the preset discrete time points, the greater the accuracy of the significance detection; the larger the preset correlation coefficient threshold, the greater the accuracy of the significance detection. Therefore, different preset discrete time points and / or different preset correlation coefficient thresholds can be gradually selected to perform multiple significance tests.

[0102] In this embodiment, the coking layer surface temperature variable Tw1 is the temperature variable of the side of the coking layer facing away from the inner wall of the settler, and is also the temperature variable of the side of the coking layer facing the raw materials in the settler. The junction temperature variable Tw2 between the coking layer and the settler is the temperature variable of the contact surface between the coking layer and the inner wall of the settler. Therefore, the coking layer surface temperature variable Tw1 and the junction temperature variable Tw2 between the coking layer and the settler are equivalent to the temperature variables between the two opposite sides of the coking layer.

[0103] After the heat passes through the coking layer, it will also be transferred to the outside through the wall of the settler. When the heat passes through the wall of the settler, the heat transfer rate calculation formula when the heat passes through the wall of the settler can be constructed according to Fourier's law, that is, the second heat transfer rate formula. The second heat transfer rate formula is used for the junction temperature variable Tw2, the external temperature of the settler Tw3 and the settler thickness variable S2 to calculate the heat transfer rate of the heat in the wall of the settler.

[0104] When the settler is in a steady-state state of production, the heat transfer rate of heat in the wall of the settler and the heat transfer rate variable of heat in the coking layer are equal, so the first heat transfer rate formula and the second heat transfer rate formula can be combined to form a coking thickness estimation formula. The coking thickness estimation formula does not have the heat transfer rate variable of heat in the coking layer and the heat transfer rate of heat in the wall of the settler. The estimation formula is used to express the calculation method of the coking layer thickness variable S1 through the coking layer surface temperature variable Tw1, the junction temperature variable Tw2, the settler external temperature Tw3 and the settler thickness variable S2. Therefore, when estimating the coking layer thickness in production, the measured surface temperature of the coking layer, the measured interface temperature between the coking layer and the settler, the measured temperature outside the settler, and the measured thickness of the settler can be detected in real time, and the coking thickness estimation value is calculated based on the coking thickness estimation formula in turn, without relying on historical data since the start of the settler.

[0105] Embodiment 2

[0106] Based on the above embodiment, a method for estimating the thickness of the coking layer on the dome of the catalytic cracking unit settler includes:

[0107] Step 1, obtaining the main body temperature and inner wall temperature of the settler fluid.

[0108] According to the actual temperature instrument of the production device, collect the temperature point data of the dense phase. If there are multiple temperature measurement points, calculate the average value. Collect the instrument data of the temperature measurement point on the inner wall of the dome dilute phase. Collect the temperature of the outer wall of the dome of the settler (outer wall of the insulation layer) and calculate the average value. If there is no actual measurement instrument for the outer wall temperature, it can be approximately 60 degrees Celsius.

[0109] There are usually multiple measuring points for the temperature at the dome, some of which are deep inside the equipment and some are located on the inner wall. We only take the temperature at the inner wall. If the production device lacks measuring points at the inner wall, it is necessary to add a temperature measuring point at the inner wall or change the depth of an existing temperature measuring point into the equipment.

[0110] Step 2, calculate the coke thickness from the heat transfer equation.

[0111] See also Figure 2 , assuming that the coking dome partially satisfies the large flat plate heat transfer assumption, the heat transfer rate from the main body of the process fluid to the inner wall of the dome is:

[0112] q=λ1*(T W1 -T W2 ) / S1 (1)

[0113] The heat transfer rate from the inner wall of the dome to the outer wall of the dome is:

[0114] q=λ2*(T W2 -T W3 ) / S2 (2)

[0115] Where q is the heat transfer rate, λ1 is the thermal conductivity of coke, λ2 is the combined thermal conductivity of the settler material and the insulation layer, S1 is the coke thickness, and S2 is the dome equipment thickness plus the insulation layer thickness. Equations (1) and (2) are obtained based on Fourier's law.

[0116] Ignoring the pressure difference between the main body of the settler fluid and the inner wall, after transformation, equations (1) and (2) are transformed into:

[0117] S1=λ1*(T W1 -T W2 )* S2 / [λ2*(T W2 -T W3 )] (3)

[0118] In formula (3), T W1 The temperature of the main body of the settler fluid can be brought in, T W2 The temperature at the inner wall can be brought in, T W3 is the outer wall temperature of the dome, about 60 degrees Celsius. Based on formula (3), the coking thickness at the dome can be roughly estimated. The heat transfer rates q of formula (1) and formula (2) must be equal when the production is in a steady state, regardless of the heat transfer medium. Because when the production is in a steady state, the heat transfer medium will not accumulate heat.

[0119] Step 3: Design of dome coking index

[0120] The coking index of the dome is calculated using the following formula:

[0121] Dome coking index = k*(settler fluid main body temperature - settler inner wall temperature) / (settler inner wall (4) temperature - 60)

[0122] In formula (4), k is a constant whose value can make the coking index within the designer's preferred range. The temperature at the inner wall is the interface between the coking layer and the dome equipment layer, which is why we need the temperature at the inner wall.

[0123] Tw1 should have been the temperature outside the coking layer, but it is not possible to install a measuring point here, so we can only find a temperature point close to it. The temperature of the main body of the settler fluid is close to its pressure and temperature.

[0124] Step 4: Industrial verification.

[0125] According to the quantitative characterization method of coking, the production data of a catalytic cracking unit settler is collected and the curve of the quantitative index of coking is drawn as follows: Figure 3 In a production cycle, even if there is data missing in the middle, it will not affect the subsequent calculation process.

[0126] Consistency verification: In general, as the device is running, the coking digital index gradually increases and reaches the maximum before the device is shut down for coking and maintenance; after the coking and maintenance, the digital index immediately drops back, and the overall trend is consistent with principles, common sense, experience, and production phenomena. It can be seen that the digital index meets the consistency requirements.

[0127] Exclusivity verification is verified by the correlation between the coking digital index and the adjustable and controllable production parameters. If the correlation between the coking index and the adjustable and controllable production parameters is very small, it can be considered that the change in the coking index is entirely caused by coking. After calculation, the Pearson correlation calculation results of the operable factors to the coking digital index N are as follows: Exclusivity verification conclusion: atomizing steam correlation -0.093; settler pressure correlation 0.198; reaction feed amount correlation 0.270. Pre-lift steam correlation 0.123. Riser outlet temperature correlation -0.017. Regeneration slide valve position 0.225. The absolute values ​​of all correlations are no more than 0.3, so it can be considered that the above operating factors have no correlation with N, that is, N contains almost no information about operating factors, which verifies the exclusivity of using N to characterize coking.

[0128] Significance verification: based on Figure 3 The digital indicators generally show an upward monotonicity within an operating cycle, which is consistent with the regular characteristics of the gradual increase in coking. Although each curve contains certain burrs, the burrs do not cover up the overall growth trend of the digital indicators. The signal-to-noise ratio is relatively high, meeting the significance requirements.

[0129] In this embodiment, a real-time evaluation method for the coking degree of the dome of the settler of a catalytic cracking unit is evaluated by an indirect index, and the basic requirements for constructing the coking index include: consistency, exclusivity, and significance. In this method, the indirect coking index is calculated based on the production instrument data at that time, without the need for historical production data. This method is to estimate using the temperature of the main body of the settler fluid, the temperature at the inner wall, and the temperature of the outer wall of the dome. In this method, the exclusivity of the coking characterization index can be verified by the correlation between the index and the adjustable and controllable parameters.

[0130] In this embodiment, the coking degree can be judged according to the coking quantitative characterization index of the present invention, just like a real instrument. The coking index is calculated based on the production instrument data at that time, without the need for historical data since the start of operation. The coking quantitative index in the invention meets consistency, exclusivity and significance.

[0131] In this embodiment, a reasonable coking characterization index of the settler dome is designed. People only need to check this characterization index to determine the depth of coking, without having to check and analyze many other production data. A reasonable characterization index is like a real detection instrument, so it can be called a soft instrument or soft measurement. The factors for calculating the index can be directly obtained from the instrument data of the device at that time, without the need for production data of the entire start-up cycle.

[0132] This indicator is equivalent to an indirect measurement of coking.

[0133] A qualified characterization indicator or soft measurement must meet at least the following three conditions:

[0134] (1) Consistency. This characterization index contains information about the degree of dome coking, which is consistent with principles, common sense, experience, and phenomena.

[0135] (2) Exclusivity. This characterization index does not contain information about instantaneous controllable and adjustable operating variables. When people observe changes in the characterization index, they must ensure that the change is indeed caused by coking, rather than by adjusting a certain operating parameter. The increase in coking is a long-term accumulation process and will not change with the change of instantaneous controllable and adjustable parameters in an instant.

[0136] (3) Significance. This characteristic index changes significantly with coking, ensuring that it is not caused by errors in instrument data, that is, the signal-to-noise ratio of this index is large.

[0137] In summary, the present invention designs a characterization index for coking of the settler dome of a catalytic cracking unit that corresponds one-to-one with the coking degree, and can be used to evaluate the coking degree of the current dome in real time based on production process data.

[0138] In this embodiment, the temperature of the process flow inside the settler is much higher than the temperature of the outer wall of the settler and the environment, so heat is transferred from the inside of the settler to the outer wall of the settler. The coking of the dome will affect the intensity of heat transfer. At any time, the intensity of heat transfer from the inside of the settler through the coke to the inner wall is equal to the intensity of heat transfer from the inner wall to the environment. The method of the present application is an indirect measurement method that uses current production process data to indirectly characterize the degree of coking, and does not require historical data of all relevant factors since the start of operation.

[0139] Embodiment 3

[0140] On the basis of the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above embodiments.

[0141] In some implementations of this embodiment, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that when the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0142] In some implementations of this embodiment, a computer program product is provided, including a computer program / instructions, characterized in that when the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0143] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components to execute the method in the above embodiments.

[0144] The computer-readable storage medium may be implemented by any type of volatile or non-volatile storage device or a combination thereof, and the computer-readable storage medium may include but is not limited to, for example, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (e.g., hard disk, floppy disk, solid-state drive, removable disk, CD-ROM, DVD-ROM, Blu-ray disc, etc.).

[0145] The computer-readable storage medium may also store at least one computer executable program / instruction, which may be, for example, a computer-readable instruction. The computer-readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The computer-readable storage medium may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device runs the computer-readable instructions stored on the computer-readable storage medium, the various methods described above may be performed.

[0146] In addition, the computer device may also include (but not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (eg, keyboard, mouse, speaker, etc.), etc.

[0147] The processor may communicate with external devices via an I / O bus via a wired or wireless network.

[0148] In one embodiment, the at least one computer executable instruction may also be compiled into or constitute a software product / computer program product, wherein one or more computer executable instructions are executed by a processor to perform the various functions and / or method steps in the embodiments described in the present technology.

[0149] In the embodiments provided in the present disclosure, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the above-mentioned module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0150] It should be noted that in the present disclosure, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element limited by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0151] Although the embodiments disclosed in the present disclosure are as above, the above contents are only embodiments adopted for facilitating the understanding of the present disclosure and are not intended to limit the present disclosure. Any technician in the technical field to which the present disclosure belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present disclosure, but the scope of patent protection of the present disclosure shall still be subject to the scope defined in the attached claims.

Claims

1. A method for estimating the thickness of the coking layer on the dome of a catalytic cracking unit settler, characterized in that: include: Obtaining a measured temperature difference between two sides of the coking layer and a measured temperature difference between two sides of a reference layer of a dome of the settler; Based on the coking thickness estimation formula, the estimated value of the coking layer thickness is calculated according to the measured temperature difference on both sides of the coking layer and the measured temperature difference on both sides of the reference layer; where: The coking thickness estimation formula is obtained by combining the heat transfer rate calculation formula of the coking layer and the heat transfer rate calculation formula of the reference layer based on the principle that the heat transfer rate is equal under the steady-state production state. The heat transfer rate calculation formula of the coking layer is obtained by correlating the temperature difference expression between the two sides of the coking layer, the thickness variable of the coking layer and the heat transfer rate variable of the coking layer based on Fourier's law. The heat transfer rate calculation formula of the reference layer is obtained by correlating the temperature difference expression between the two sides of the reference layer and the heat transfer rate variable of the reference layer based on Fourier's law.

2. The estimation method according to claim 1, characterized in that The step of obtaining the measured temperature difference between the two sides of the coking layer comprises: obtaining the bulk temperature of the fluid in the settler; Obtain the inner wall temperature of the dome of the settler; The difference between the bulk temperature of the fluid in the settler and the inner wall temperature of the dome of the settler is calculated to obtain the measured temperature difference between the two sides of the coking layer.

3. The estimation method according to claim 1, characterized in that The steps of obtaining the measured temperature difference between the two sides of the reference layer include: Obtain the inner wall temperature of the dome of the settler; Obtain the outer wall temperature of the settler; The difference between the inner wall temperature of the dome of the settler and the outer wall temperature of the settler is calculated to obtain the measured temperature difference between the two sides of the reference layer.

4. The estimation method according to claim 1, characterized in that The estimation formula of coking thickness is as follows: Among them, S1 is the estimated value of the coking layer thickness, T w1 and T w2 is the temperature on both sides of the coking layer, T v1 and T v2 is the temperature on both sides of the reference layer, and k is the coefficient.

5. The estimation method according to claim 1, characterized in that The estimation formula of coking thickness is as follows: Among them, S1 is the estimated value of the coking layer thickness, T w1 is the bulk temperature of the fluid in the settler, T w2 is the inner wall temperature of the dome of the settler, T w3 is the outer wall temperature of the insulation layer of the dome of the settler, and k is the coefficient.

6. The estimation method according to any one of claims 1 to 5, characterized in that Estimation methods also include: Obtaining a coke thickness estimation value calculated using a coke thickness estimation formula within a preset time period before coke cleaning and an estimated coke thickness value within a preset time period after coke cleaning; Detecting changes in the estimated value of coke thickness within a preset period of time before defocusing and changes in the estimated value of coke thickness within a preset period of time after defocusing; When the estimated coke thickness increases to a first coke thickness value within a preset period before defocusing and starts to increase with a second coke thickness value within a preset period after defocusing, a result that meets the consistency requirements is output, wherein the first coke thickness value is greater than the second coke thickness value.

7. The estimation method according to any one of claims 1 to 5, characterized in that Estimation methods also include: Obtaining the values ​​of measurable production parameters; Calculate the correlation between the numerical value of the measurable production parameter and the estimated value of the coke thickness to obtain a correlation coefficient; Check whether the absolute value of the correlation coefficient is less than or equal to the correlation threshold; When the absolute value of the correlation coefficient is less than or equal to the correlation threshold, a result that meets the coking exclusivity is output.

8. The estimation method according to any one of claims 1 to 5, characterized in that: Estimation methods also include: Obtaining the estimated value of coking thickness corresponding to a preset discrete time point within the operation period, where the operation period is the period between two adjacent coking cleaning operations; Calculate the interval between each preset discrete time point and the end of the last coking cleaning work to obtain the operation time of each preset discrete time point; Detect whether the estimated coking thickness corresponding to the preset discrete time point is positively correlated with the operation time; When the estimated coking thickness corresponding to the preset discrete time point is positively correlated with the operation time, the output is a significant result.

9. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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