RU188626U1 - DEVICE FOR ALKYLATION OF ISOBUTANE OLEFINES IN A REACTOR WITH A STATIONARY CATALYST LAYER - Google Patents

Abstract

The utility model relates to apparatuses of the chemical and petrochemical industry and is intended for reactors with stationary stationary heterogeneous catalysts, in which it is important not to overheat the bulk catalyst bed with the furnace and to carry out the process specifically in the gas or liquid phase, in particular for isobutane alkylation with C2-C4 olefins. A device for alkylation of isobutane with olefins, comprising a three-phase reactor, filled with a fixed catalyst bed, located between the layers of inert packing, a heating device connected to the reactor, a feedstock injection unit, a reaction products outlet unit and a control means installed in the reactor, according to which the control means is device for measuring the level of the liquid phase - multipoint thermocouple with 3-9 measuring points located coaxially with the reactor so that some of them are located inside catalyst layer, part inside the inert nozzle layer above the catalyst layer, part in the gas phase above the nozzle layer, with one of the measurement points in the catalyst layer located in the middle of it. Technical result: the proposed device allows you to control the process of isobutane alkylation in a simple and reliable way Olefins, due to which it is possible to recognize the alkylation process in the gas or liquid phase. approx., 2 tab., 2 ill.

Description

The invention relates to apparatuses of the chemical and petrochemical industry and is intended for reactors with a stationary fixed heterogeneous catalyst, in which it is important to conduct the process specifically in the gas or liquid phase, in particular for the alkylation of isobutane with C2-C4 olefins.

Automobile gasolines are one of the most large-tonnage products of oil refining, and its composition in recent years has undergone major changes in component, chemical and hydrocarbon compositions due to the toughening to it of the requirements caused by the protection of the ecological environment. Thus, alkylate, the product of the alkylation of isobutane with C2-C4 olefins, which does not contain aromatic hydrocarbons and sulfur-containing compounds and is superior to most high-octane gasoline components, has become the main part of motor gasoline.

It is known that the process of alkylation of isobutane with olefins can be carried out in the gas, liquid phases or in the "structured" mode (hereinafter ASR), described in the patent RU 2637922 (С07С 2/58, С07С 9/00, B01J 8/06, published 08.12.2017 g.). According to the invention, the method of alkylation of isobutane is carried out in a three-phase reactor with a fixed catalyst bed, butylenes are fed to each catalyst layer, and isobutane, taken in excess, in the upper part of the reactor, the alkylation reaction is carried out, separated and returned to the recycled unreacted isobutane and output the resulting alkyl benzine. The temperature and pressure are chosen so that the isobutane vapor is in a state of saturation, and the additional evaporation of the liquid in the reactor under the influence of the heat of reaction provides isothermal conditions for the alkylation process. The liquid flows freely without bubbling under the action of gravity at a volume velocity of not more than Wmax equal to

and not less than Wmin equal

and is implemented using a device for the alkylation of isobutane with olefins, including a three-phase reactor with a fixed catalyst bed, located between the layers of inert packing, equipped with a thermocouple to determine the temperature in the reaction system.

The described method allows you to successfully maintain the stability of the process while maintaining a high activity of the catalyst for a long time and has established itself better than others.

The disadvantage of the described method lies in the complexity of the calculation required to monitor the stability of the alkylation process and the need to possess information on important parameters of the equations, such as steam content under the reaction conditions, the density of the liquid in the reactor, the linear flow rate of the liquid, the viscosity of the liquid in the reactor, etc. d.

For example, only the maximum linear velocity of a free-flowing liquid Umax, m / s, is calculated based on the system of equations

where H is the height of the catalyst bed, m, g is the acceleration of free fall,

m / s ² , Δp _sweat - lost head, Pa, d _p - average particle diameter of the catalyst, m, μ - fluid viscosity, Pa / s. The minimum linear velocity of the free flowing liquid U _min , m / s, is equal to

где Ga - критерий Галилея, определяемый по

where Ga is the Galilean criterion, defined by

μ - динамическая вязкость жидкости, Па/с, ρ_ж - плотность, г/м³; d_p - средний диаметр частицы катализатора, м,formula:

μ is the dynamic viscosity of the fluid, Pa / s, ρ _{and the} density, g / m ³ ; d _p - the average particle diameter of the catalyst, m,

где Ga - критерий Галилея,

where Ga is the Galilean criterion,

μ - динамическая вязкость жидкости, Па/с, ρ_ж - плотность, г/м³; d_p - средний диаметр частицы катализатора, м, что связано с замером и расчетом многих параметров одновременно, что безусловно требует значительного времени, усилий и затрат, и может привести к нарушению режима за счет запоздалого реагирования в случае выхода линейной скорости за допустимые пределы.determined by the formula:

μ is the dynamic viscosity of the fluid, Pa / s, ρ _{and the} density, g / m ³ ; d _p is the average diameter of the catalyst particle, m, which is associated with the measurement and calculation of many parameters at the same time, which certainly requires considerable time, effort and cost, and can lead to a violation of the regime due to late response in the event that the linear velocity goes beyond acceptable limits.

The task of the utility model is to develop a device that allows you to monitor the state of the reaction system in the process of alkylation of isobutane with olefins in a simpler and faster way by measuring the liquid level in the bulk layers without disturbing the mode of operation of the reaction system.

The task is solved by the fact that the proposed device for the alkylation of isobutane with olefins, including a three-phase reactor, filled with a fixed catalyst bed, located between the layers of inert nozzles, a heating device connected to the reactor, the input unit of the raw material, the output node of the reaction products and control means installed in the reactor , according to which, the control device is a device for measuring the level of the liquid phase - a multipoint thermocouple with 3-9 measuring points located coaxially about the reactor so that part of them is located inside the catalyst layer, part inside the inert nozzle layer above the catalyst layer, part in the gas phase above the nozzle layer, and one of the measurement points in the catalyst layer is located in its middle.

The proposed device allows a simple and reliable way to exercise control over the process of alkylation of isobutane with olefins, thanks to which it is possible to recognize the alkylation process in the gas or liquid phase.

This device makes it possible to work particularly effectively and obviously in the conditions of laboratory, pilot and pilot plants with vertical reactors using heterogeneous catalysts.

The principle of operation of the device lies in the fact that the latter controls the mode of alkylation of olefin isobutane, namely, the determination of the state of the catalyst: whether it is completely filled with liquid or not (liquid or gas-phase process), which together contributes to the correct response in the case of observed violations in the given experimental modes .

In order to control the process of alkylation of isobutane with olefins, it is necessary to know the conditions under which it is carried out, namely in the gas or liquid phase, which in many industrial plants with a stationary layer can be achieved using special level gauges, which is not possible for laboratory and stand installations.

A diagram of the device for the alkylation of isobutane with olefins in a reactor with a fixed catalyst bed using a multi-point thermocouple located coaxially with the reactor is shown in FIG. 1А when using a three-point thermocouple, the measuring points of which are set so as to conduct temperature measurement:

- in the center of the catalyst bed;

- in the center of the layer of inert packing located above the catalyst bed, providing the best mixing, distribution of reaction components and maintaining uniform heating of the catalyst bed;

- in the "gas phase" over the catalyst layers and nozzles in the reactor. The number of measured points in the layers of the catalyst and inert

nozzles, as well as over bulk layers (in the gas phase) can be increased, which contributes to a more accurate determination of the location of the phase separation (liquid level). For example, as shown in FIG. 1B, the installation of an additional two measuring points for each of the above, located so as to conduct temperature measurement:

- in the catalyst bed so that the measuring points of the thermocouple are evenly spaced along the height of the catalyst bed;

- in the layer of inert packing located above the catalyst layer, providing the best mixing, distribution of reaction components and maintaining uniform heating of the catalyst layer, so that the measuring points of the thermocouple are evenly distributed along the height of the layer of inert packing;

- in the "gas phase" over the catalyst layers and inert nozzles in the reactor so that the measuring points of the thermocouple are evenly located above the bulk layers.

The explanation of the figures in FIG. 1A and FIG. 1B:

1 - reactor;

2 - furnace, carrying out heating of the reactor;

3 - heat exchanger;

4 - separator;

5 - catalyst bed;

6 - a layer of inert packing;

7 - multipoint thermocouple;

8 - thermocouple measuring points;

9 - input of raw materials into the system;

10 - output of the reaction products.

The system, where the proposed device for the alkylation of isobutane with olefins, includes a reactor (1), which is a cylindrical apparatus, heated with a furnace (2). Above the reactor is a heat exchanger (3), in which the raw material is heated and condensation of evaporated isobutane takes place, and to which the raw material input unit is connected to the system (9). Under the reactor there is a separator (4) in which isobutane is separated from the reaction products during the evaporation of isobutane from the liquid, and to which the output node of the reaction products (10) from the system is attached.

The device works as follows.

After installation in the system of a given mode, olefin-containing raw materials are fed into the system through the input unit of the raw material (9) through the heat exchanger (3) to the reactor (1), where it contacts the catalyst.

In the reactor, the isobutane is alkylated with olefins to produce isooctanes at an optimal temperature of 80 ° C and a pressure of 1.32 MPa:

iC4H10 + C4H8 → iC8H18

A mixture of reaction products containing isobutane, the desired reaction products (isooctanes) and by-products of the process enters the separator (4), where the isobutane partially evaporates and enters through the reactor (1) into the heat exchanger (3), in which it condenses and enters back into the reactor . From the bottom of the separator (4) remove the liquid (10), which is the reaction products, they are collected and analyzed.

Optimal conditions for the process of alkylation of isobutane with butylenes - carrying out the process in a flooded mode of catalyst or ASR.

Thus, above the catalyst surface should be the liquid level, which can be determined by the readings of multipoint thermocouples. It is well known that the temperature of alkylation of isobutane with olefins in the gas phase is higher than the temperature in the liquid phase, ceteris paribus, and, therefore, the difference in these temperature readings can be judged on the presence or absence of liquid above and in the catalyst bed. Moreover, the temperature difference between the temperature in the liquid and gas phases is 2-5 ° C, which can contribute to a simple detection of the state of the catalyst (it is filled with liquid or not) and timely regulation of the system with the slightest signs of violation - a decrease in the liquid level above the catalyst bed, namely :

- reduction of heat exchanger heating, if its heating is carried out due to electric power, then by reducing power, if the heat exchanger works by heating circulating cold water outside the system, then by increasing the amount of circulating cold water;

-reduction of heating of the separator, if the cause of the decrease in the level of the liquid is overheating of the liquid in the separator.

The following examples illustrate the proposed technical solution.

Example 1

The alkylation process is carried out in a system in which the diameter of the reactor is 18 mm and a three-point thermocouple is installed, with the measuring points of the thermocouple located 60 mm and 107 mm from the upper measuring point (above the bulk layer), which correspond to the middle of the quartz and catalyst layers, respectively.

The process of alkylation of isobutane with olefins is carried out in a flooded catalyst bed at a temperature in the reaction zone - 80 ° C, pressure - 1.32 MPa, which corresponds to the equilibrium vapor-liquid hydrocarbon mixture for 4 hours. Moreover, in the course of the experiment, the liquid level is maintained above the bulk inert layer of the reactor, characterized by the fact that there is a difference in temperature in the bulk layer (in the catalyst layers and inert packing located above the catalyst layer, namely 80 ° C) and above the bulk layers, in gas phase (85 ° C), and the difference in temperature is from 2 to 5 ° C.

This mode corresponds to the liquid-phase process, during which not only the catalyst layer, but also the inert packing are in the liquid phase, and there is no overheating in the bulk layers of the reaction system.

The ratio of isobutane to olefins in the feedstock fed to the reaction zone is 10: 1.

At the end of the experiment, the resulting liquid product is stabilized, and then the resulting alkylate, which is a mixture of C5-C9 paraffinic hydrocarbon isomers, and gaseous products, consisting mainly of unreacted isobutane, are analyzed by using a gas adsorption chromatography on a Crytolux-4000M chromatograph on SE- 30 and with aluminum oxide, respectively. We used the “NetChrom” program, designed to automate the operation of the “Crystallux 4000M” chromatograph.

According to the data obtained, the main process indicators are calculated:

- conversion of olefins (X (O)) - the ratio of the amount of converted raw materials to taken, characterizes the completeness of the use of raw materials and is expressed in mass. %:

where: X (O) is the conversion of olefins,% of the mass.

C (O) feedstock - the concentration of olefins in the feedstock,% by weight;

m (raw materials) is the mass of raw materials, g;

C (O) prod. - the concentration of olefins in the product,% by mass;

m (product) is the mass of the product, g;

- the yield of alkylbenzene from olefins in the feedstock (ϕ (AB)) is the yield of the reaction product (alkylate) in terms of the olefins used in the feedstock, and is expressed in mass. %:

where ϕ (AB) - output alkylbenzene,% of the mass.

m (product) is the mass of the product, g;

m (raw materials) is the mass of raw materials, g;

C (O) feedstock - the concentration of olefins in the feedstock,% by weight;

M (AB) - alkylbenzene molar mass, g / mol;

M (O) is the molar mass of olefins, g / mol.

- reaction selectivity is the relative concentration of the isooctane fraction, the most valuable component of gasoline, on the reaction products and is expressed in mass. %:

where δ (IZO) is the selectivity of the reaction by the target product,% by mass;

C (IZO) is the concentration of the isooctane fraction in the product,% by mass;

C (cont.) - the total concentration of the reaction products,% of the mass.

The results of the experiment and the quality of the product are shown in table 1.

Example 2

The process of alkylation in the flooded mode of the catalyst at a temperature in the reaction zone - 80 ° C, pressure - 1.32 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture for 4 hours using a three-point thermocouple.

Moreover, in the course of the experiment, the liquid level over the bulk layer of the reactor is reduced so that at the initial moment the temperature in the bulk catalyst layer is (80 ° C), and above the bulk layer, in the gas phase (85 ° C), and the temperature difference is from 2 to 5 ° C, and with the further conduct of the experiment, the difference in temperatures above the bulk layer and in it decreases due to the increase in temperature in the catalyst bed - the "drying" of the catalyst.

This mode corresponds to the liquid-phase process, during which the layers of the catalyst and inert nozzles are in the liquid phase, but there is an overheating of the reactor system at the inner wall of the reactor.

The phase boundary is detected in the temperature difference in the bulk layers and / or above the bulk layers, and the allowable range is from 2 to 5 ° C.

The ratio of isobutane to olefins in the feedstock fed to the reaction zone is 10: 1.

The results of the experiment and the quality of the product are shown in table 1.

Example 3

The alkylation process is carried out at a temperature in the reaction zone of 80 ° C, a pressure of 1.32 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture for 4 hours using a three-point thermocouple.

Moreover, during the experiment, the temperature in the bulk layers and above them is maintained elevated (85 ° C), and this is not achieved due to overheating of the furnace.

This mode corresponds to the process in the gas phase.

The ratio of isobutane to olefins in the feedstock fed to the reaction zone is 10: 1.

The results of the experiment and the quality of the product are shown in table 1.

Example 4

The process of alkylation of isobutane with olefins is carried out in a flooded catalyst bed at a temperature in the reaction zone - 80 ° C, pressure - 1.32 MPa, which corresponds to the equilibrium vapor-liquid hydrocarbon mixture for 4 hours using a nine-point thermocouple. Moreover, in the course of the experiment, the liquid level is maintained above the bulk inert layer of the reactor, characterized by the fact that there is a difference in temperature in the bulk layer (in the catalyst layers and inert packing located above the catalyst layer, namely 80 ° C) and above the bulk layers, in gas phase, and the change in the position of the phase boundary was observed on the difference of temperature indicators, which ranged from 2 to 5 ° C.

This mode corresponds to the liquid-phase process, during which not only the catalyst layer, but also the inert packing are in the liquid phase and there is no overheating in the bulk layers of the reaction system.

The ratio of isobutane to olefins in the feedstock fed to the reaction zone is 10: 1.

The results of the experiment and the quality of the product are shown in table 2.

Example 5

The alkylation process is carried out in the flooded mode of the catalyst at a temperature in the reaction zone - 80 ° C, pressure - 1.32 MPa, which corresponds to the equilibrium vapor-liquid hydrocarbon mixture for 4 hours using a nine-point thermocouple.

Moreover, at the initial moment of the experiment, the liquid level is maintained above the bulk inert layer of the reactor, characterized by the fact that there is a difference in temperature in the bulk layer (in the catalyst layers and inert packing located above the catalyst layer, namely 80 ° C) and above the bulk layers, in the gas phase, and the change in the position of the phase boundary was observed on the difference in temperature indicators, which ranged from 2 to 5 ° C. This mode corresponds to the liquid-phase process, during which not only the catalyst layer, but also the inert packing are in the liquid phase, but the inert packing may not be completely in the liquid phase. However, with further experimentation, the difference in temperatures above the bulk layer and in it decreases due to a partial increase in temperature in the catalyst bed - the “drying” of the catalyst. After breaking the experimental mode (partial “drying” of the catalyst), actions are carried out to restore the experimental conditions, namely, increasing the flow of circulating water to remove more heat from the heat exchanger and reducing the separator heating, resulting in a liquid level (as indicated by a multipoint thermocouple) above the catalyst layer .

The ratio of isobutane to olefins in the feedstock fed to the reaction zone is 10: 1.

The results of the experiment and the quality of the product are shown in table 2.

where "..." is the change in temperature during the experiment.

where "..." is the change in temperature during the experiment.

As can be seen from Table 1, an increase in temperature in the catalyst bed corresponds to a decrease in the liquid level in the system (dried catalyst mode), which leads to a deterioration in process performance, namely, a decrease in olefin conversion from 100 to 96%, alkylate yield, which characterizes work stability, from 198 up to 189 mass. % and the selectivity for the target product is the concentration of isooctanes in the reaction products from 82.47 to 76.42 mass. %, in particular trimethylpentane (TMP) from 72.94 to 67.77 mass. %; however, there is also a deterioration in the quality of products due to an increase in the amount of by-products, namely, C5-C7 hydrocarbons from 11.81 to 13.11 wt. % and high-boiling hydrocarbons from 5.72 to 10.47 wt. %). When carrying out the process completely in the gas phase, the process indicators deteriorate even more.

As can be seen from Table 2, in the course of the experiment, thanks to a nine-point thermocouple, one can speak of a more accurate location of the phase boundary (speak of the liquid level) than in the case of using a three-point thermometer and react in a timely manner, not allowing the entire catalyst layer to be in the gas phase. It is also shown that when restoring the experiment mode (example 5), the process indicators and the quality of the reaction products decrease in comparison with the liquid-phase process (examples 1 and 4), but do not deteriorate to the results obtained during the gas-phase process (example 3) or violation of the regime without its restoration (example 2).

Thus, the proposed technical solution allows a simple and reliable way to monitor the quality of the process without disrupting the operating system of the reaction system by detecting the phase boundary.

Claims (1)

A device for the alkylation of isobutane with olefins, comprising a three-phase reactor, filled with a fixed catalyst bed, located between the inert packing layers, a heating device connected to the reactor, a feedstock injection unit, a reaction products outlet unit and a control means installed in the reactor, characterized in that the control means is a device for measuring the level of the liquid phase - a multipoint thermocouple with 3-9 measuring points located coaxially with the reactor so that some of them are located inside three catalyst layer part inside the layer of inert packing above the catalyst bed, part of the gas phase above the packing layer, wherein one of the measurement points in the catalyst bed is situated in its middle.

Images