KR20240114174A - A Method for reducing fouling in a device - Google Patents

Abstract

The present disclosure provides a method for reducing fouling in a device, comprising the steps of: a) injecting a passivation additive into the device along with feedstock supply; and b) injecting a dispersant into the device in conjunction with the feedstock supply.

Description

{A Method for reducing fouling in a device}

The present disclosure relates to a method for reducing fouling within a device, and more specifically, to a method for reducing and/or preventing fouling occurring inside a device such as a heat exchanger used in a petrochemical process.

In equipment used in petrochemical processes, fouling occurs inside the equipment through which petroleum feedstock passes. It is known that such fouling is caused by asphaltenes, inorganic iron, etc. contained in petroleum feedstock, but the cause of fouling in the present disclosure is not limited thereto. In particular, in high-temperature devices such as heat exchangers, the temperature of the petroleum feedstock is raised through heat exchange. As the temperature of the feedstock increases, the possibility of fouling occurring on the internal surface of the device increases. This fouling increases thermal resistance, causing a problem of reducing heat transfer efficiency from the heat exchanger to the petroleum feedstock.

In order to solve the above problems in petrochemical processes, efforts are being made to reduce fouling within the equipment or prevent fouling from occurring. As a representative method, a method of injecting additives into the device along with the supply of petroleum feedstock is known.

Examples of additives include dispersants. The dispersant suppresses fouling by dispersing substances that cause fouling within the petroleum feedstock and preventing the substances from being deposited on the internal surface of the device.

US 2015-0232362 A1 US 2016-0060552 A1

The present disclosure is concerned with providing a new method for more efficiently reducing and/or preventing fouling in equipment used in petrochemical processes.

One aspect of the present disclosure is a method for reducing fouling in a device, comprising the steps of a) injecting a passivation additive into the device along with feeding feedstock; and b) injecting a dispersant into the device in conjunction with feeding the feedstock.

According to one embodiment of the present disclosure, the device includes a heat exchanger, furnace, distillation column, boiler, or desalter.

According to one embodiment of the present disclosure, steps a) and b) are performed sequentially, and while step b) is performed, step a) is not performed.

According to one embodiment of the present disclosure, the feedstock comprises greater than 0 to 20 wt% asphaltenes.

According to one embodiment of the present disclosure, the feedstock includes crude oil, atmospheric residue, heavy oil, vacuum residue, or a combination thereof.

According to one embodiment of the present disclosure, the passivation additive is a phosphate-based passivation additive.

According to one embodiment of the present disclosure, the thermal efficiency of a device subjected to the method is improved by at least 70% compared to the thermal efficiency of a device in which neither steps a) nor b) are performed.

Through the method of the present disclosure, fouling within the device can be reduced, and as a result, there is an advantage in maintaining high heat transfer efficiency of the device.

1 is a schematic diagram of experimental equipment used in an experimental example of the present disclosure;
Figure 2 is a graph of delta T versus time showing the results of an experimental example of the present disclosure.

The objectives, specific advantages and novel features of the present disclosure will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings, but the present disclosure is not necessarily limited thereto. Additionally, in describing the present disclosure, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted.

The present disclosure provides a method for reducing fouling in a device. The method includes the steps of a) injecting a passivation additive into the device along with feeding the feedstock; and b) injecting a dispersant into the device in conjunction with feeding the feedstock.

Fouling can generally be defined as 'undesirable solid deposits deposited at an interface'. In the present disclosure, fouling more preferably refers to deposits deposited on the internal surfaces of equipment used in a petroleum refining process.

In the present disclosure, the device may be a device used in a petrochemical process. Strictly speaking, in the present disclosure, the device is not particularly limited as long as it is a device used in a petrochemical process that is likely to cause fouling due to feedstock passing through the device. According to one embodiment of the present disclosure, the device may include a heat exchanger, a furnace, a distillation column, a boiler, or a desalter.

The main cause of fouling is asphaltene. Therefore, according to one embodiment of the present disclosure, the feedstock may include greater than 0 to about 20 wt% of asphaltene based on the total weight of the feedstock. Preferably, the feedstock may include about 0.1 to about 10 wt% asphaltenes. The feedstock of the present disclosure is not particularly limited as long as it is oil used in petrochemical processes. In particular, the feedstock may be oil supplied to the devices described above. For example, the feedstock may include crude oil, atmospheric residue, heavy oil, vacuum residue, or a combination thereof.

Typically, initial corrosion of device internal surfaces occurs due to sulfurization by sulfur compounds in the feedstock, producing iron sulfide compounds on the surfaces. Iron sulfide compounds have sticky properties, which promotes the deposition of fouling-causing substances, such as asphaltenes, on the device's internal surfaces.

The method of reducing fouling in a device of the present disclosure includes first injecting a passivation additive into the device along with supply of feedstock. The passivation additive is injected into the device at the same time as the feedstock and forms a layer through an oxidation reaction on the metal surfaces inside the device. In this disclosure, this layer is referred to as a passivation layer. In the present disclosure, 'passivation additive' can be used interchangeably with 'film former' or 'corrosion inhibitor', and 'passivation layer' can be used interchangeably with 'coating' or 'film'. . The passivation layer blocks fouling-causing substances in the feedstock from direct contact with the device's internal surfaces, thereby preventing fouling-causing substances from being deposited on the device's internal surfaces. This can ultimately delay the occurrence of fouling.

However, in order to delay the occurrence of fouling using a passivation additive, the passivation additive must be continuously supplied along with the feedstock. As will be described later, phosphorus salt-based passivation additives are currently commonly used as passivation additives. Continuous supply of high concentrations of phosphate is undesirable as it may adversely affect the quality of the downstream catalyst and the resulting product.

Accordingly, in the present disclosure, the step of injecting the passivation additive into the device is characterized in that it is performed only for a relatively short time at the beginning of the process.

In the present disclosure, the passivation additive injection step may be performed simultaneously with the start of supply of the feedstock. In this case, the passivation additive may be previously mixed into the feedstock to form a mixture of feedstock and passivation additive, which may be fed into the device. Alternatively, the feedstock and passivation additive may each be supplied to the device through separate inlets.

The step of injecting the passivation additive into the device may be performed early in the process for a sufficient time to form a passivation layer on the entire surface of the metal inside the reactor. According to one embodiment of the present disclosure, the step of injecting the passivation additive into the device may be performed for about 12 hours to about 100 hours. Preferably, this step may be performed for about 18 hours to about 84 hours, more preferably for about 24 hours to about 72 hours.

Passivation additives can be injected in high concentrations early in the process. In one embodiment of the present disclosure, the concentration of the passivation additive may be about 10 to about 2000 ppm based on the volume of the feedstock. Preferably, the concentration may be about 20 to about 1500 ppm, more preferably about 30 to about 1000 ppm. If the concentration of the passivation additive is lower than the above range, a problem may occur in that a sufficient passivation layer is not formed. On the other hand, if the concentration of the passivation additive exceeds the above range, problems may arise that negatively affect the catalyst in the downstream process and the resulting product. In the present disclosure, the type of passivation additive is not particularly limited as long as it is a passivation additive that can be used to reduce fouling in a petrochemical process. In one embodiment of the present disclosure, the passivation additive may be a phosphate-based passivation additive.

The method of the present disclosure includes the step of injecting a dispersant into the device. The dispersing agent disperses fouling-causing substances present in the feedstock and prevents agglomeration between fouling-causing substances and deposition on the internal surface of the device. However, the sole use of a dispersant has the problem of not preventing fouling due to initial corrosion of the internal surface of the device.

Accordingly, the method of the present disclosure adopts a method of injecting a dispersant after the passivation additive injection step. According to one embodiment of the present disclosure, the dispersant injection step may be performed together with the supply of feedstock. In this case, the dispersant may be previously mixed with the feedstock to form a mixture of feedstock and dispersant, and the mixture may be fed into the device. Alternatively, the feedstock and dispersant may each be supplied to the device through separate inlets.

According to one embodiment of the present disclosure, the passivation additive injection step and the dispersant addition step are performed sequentially, and while the dispersant addition step is performed, the passivation additive injection step is not performed.

In general, the price of passivation additives is higher than that of dispersants. In the method of the present disclosure, the passivation additive is injected together with the feedstock only at the beginning of the process, and then only the dispersant is injected together with the feedstock, and thus a better fouling reduction effect is expected to be achieved compared to the process of using the passivation additive and the dispersant alone. You can. In addition, the problems associated with the process of continuously using a passivation additive can be avoided, and it is also more advantageous in terms of cost.

In the present disclosure, the type of dispersant is not particularly limited as long as it is used to reduce fouling in a petrochemical process. In one embodiment of the present disclosure, the dispersant may be an asphaltene dispersant. As an exemplary asphaltene dispersant, a polyisobutylene (PIB)-based dispersant may be used, but is not limited thereto.

In one embodiment of the present disclosure, the concentration of the dispersant may be about 5 to 50 ppm based on the volume of the feedstock. Preferably, the concentration may be about 5 to 30 ppm, more preferably about 10 to 20 ppm. Depending on the type and content of fouling-causing substances in the feedstock, the dispersant may be used at a concentration outside the above range.

By using the fouling reduction method of the present disclosure, unlike using the passivation additive alone, there is no need to continuously inject the passivation additive, which is advantageous from an economic perspective. In addition, by using the fouling reduction method of the present disclosure, unlike using the dispersant alone, there is an advantage that the problem of fouling formation inside the device due to initial surface corrosion can be solved. Ultimately, by using the method of the present disclosure, it is possible to efficiently control the occurrence of fouling and maintain excellent heat transfer efficiency.

According to one embodiment of the present disclosure, when the method of the present disclosure is implemented, the thermal efficiency of the device can be improved by at least 70% compared to the thermal efficiency of the device without injection of both the passivation additive and the dispersant. Preferably, the thermal efficiency of a device using the method of the present disclosure can be improved by at least 80%, more preferably at least 90%, and even more preferably about 90 to 95% compared to a device that does not perform the method of the present disclosure.

Hereinafter, preferred embodiments are presented to aid understanding of the present disclosure. However, the following examples are provided only to facilitate easier understanding of the present disclosure, and the present disclosure is not limited thereto.

Example

The experimental apparatus was designed as shown in Figure 1. Referring to Figure 1, the feed present in the reservoir flows in through an inlet, passes through a heat exchanger including a heated rod, and is discharged through an outlet. The fluid discharged through the outlet is stored back in the reservoir. The temperature of the fluid at the inlet and outlet of the heat exchanger was measured. Here, the temperature of the heated rod was set to be maintained at approximately 400°C. The feed was introduced at a rate of approximately 1.0 ml/min. The feed contained oil. The API specific gravity of the oil was about 30 °API, and the asphaltene content in the oil was about 3 wt%.

Experimental Example 1

Only oil was passed through the heat exchanger, without dispersants and passivation additives (not shown in Figure 1). The temperature of the fluid at the outlet was measured over time. The results are shown as a graph of delta T versus time in Figure 2. Here, delta T means the temperature of the outlet fluid at a specific time minus the temperature of the initial outlet fluid (T _time - T ₀ ).

Experimental Example 2

Feed 1 containing oil and a passivation additive (about 400 ppm relative to the oil volume) was passed through the heat exchanger, and other than that, the experiment was conducted in the same manner as in Experimental Example 1. The results are shown in Figure 2. Suez's Thermoflo 7R29 product was used as a passivation additive.

Experimental Example 3

Feed 2 containing oil and asphaltene dispersant (approximately 160 ppm relative to oil volume) was passed through the heat exchanger, and other than that, the experiment was performed in the same manner as in Experimental Example 1. The results are shown in Figure 2. Suez's Thermoflo 7049 product was used as an asphaltene dispersant.

Experimental Example 4

Feed 1 containing oil and passivation additive was passed through a heat exchanger for about 120 minutes, and then feed 2 was passed through the heat exchanger. Afterwards, the experiment was conducted in the same manner as in Experimental Example 1. The results are shown in Figure 2. The results of Experimental Example 4 are shown in FIG. 2 with 0 min being the time when feed 2 is first supplied to the heat exchanger.

Referring to Figure 2, it can be seen that the temperature difference with the temperature of the fluid discharged from the initial outlet tends to increase as time passes. This is expected to be the result of increased thermal resistance of the heat exchanger due to fouling and reduced heat conduction efficiency. In the case of Experimental Example 4 using the method of the present disclosure, it was possible to achieve the absolute value of the Delta T value below 1°C even after a considerable period of time, confirming that an excellent fouling reduction effect can be achieved.

All simple modifications or changes to the present disclosure fall within the scope of the present disclosure, and the specific scope of protection of the present disclosure will be made clear by the appended claims.

Claims (7)

As a method for reducing fouling within the device,
a) Injecting a passivation additive into the device together with the feedstock supply; and
b) A method for reducing fouling in a device comprising the step of injecting a dispersant into the device in conjunction with the feedstock supply. In claim 1,
A method for reducing fouling in a device, wherein the device includes a heat exchanger, furnace, distillation column, boiler, or desalter. In claim 1,
Steps a) and b) are performed sequentially,
A method for reducing fouling in a device, wherein while step b) is performed, step a) is not performed. In claim 1,
A method for reducing fouling in a device, wherein the feedstock comprises greater than 0 to 20 wt% asphaltenes. In claim 1,
The feedstock includes crude oil, atmospheric residue, heavy oil, vacuum residue, or a combination thereof. In claim 1,
A method for reducing fouling in a device, wherein the passivation additive is a phosphate-based passivation additive. In claim 1,
A method for reducing fouling in a device, wherein the thermal efficiency of the device performing the method is improved by at least 70% compared to the thermal efficiency of the device not performing both steps a) and b).