System and method for cleaning and condensing pyrolysis gases from a pyrolysis reactor

Abstract

The present invention relates to a system for cleaning and condensing pyrolysis gases from a reactor, said system including a condensation tube where the gases are sprayed with a fluid to remove residual carbon black (rCB) and to condense hydrocarbons. A first condenser aids in condensing additional hydrocarbons, and a reservoir separates the rCB from the fluid and stores the resulting mixture. Optionally, a second condenser carries out additional cleaning and condensation. The system may incorporate spiral spray nozzles and a system for recirculating the fluid, which may be pyrolytic oil (TPO). A method associated with the system involves spraying the gases with the fluid to capture rCB and condense hydrocarbons, cooling the gases, separating the rCB from the fluid, mixing the condensed hydrocarbons with the clean fluid and recirculating a part of the mixture for reuse. It may include an additional step of cooling and decanting the rCB in the form of sludge.

Description

[0001] SYSTEM AND PROCEDURE FOR CLEANING AND CONDENSING PYROLYSIS GASES FROM A PYROLYSIS REACTOR TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates to a system for cleaning and condensing gases from a pyrolysis reactor whose functions include condensing hydrocarbons with boiling points higher or similar to ambient temperature, preventing the accumulation of black carbon residues, rCB hereafter, on the walls of the different components of the system, and separating the accumulated rCB from the condensed hydrocarbons.

[0003] STATE OF THE ART

[0004] In solid waste management plants, for example, End-of-Life Tires (ELTs) are commonly used. In this regard, the proper management of the pyrolysis gases generated in the pyrolysis reactor by condensation systems is essential to ensure both system efficiency and operational safety. The pyrolysis reactor outlet gases comprise three main components: a condensable fraction, a non-condensable fraction, and recycled black carbon (rCB) dust. The condensable fraction consists mainly of hydrocarbons, while the non-condensable fraction includes gases such as hydrogen and methane. This set of gaseous products, if not managed properly, can seriously affect the system's operability and safety.

[0005] One of the main technical challenges in these processes is the condensation of gases inside the pipes that transport the products to the condensation modules. During this process, the condensable fractions, along with suspended rCB, begin to accumulate on the inner walls of the pipes. Over time, these accumulations become significant blockages that can completely obstruct the flow of gases, forcing a shutdown for cleaning and maintenance. This phenomenon causes constant operational interruptions, as the condensation systems employ traditional methods, such as shell and tube condensers. These can require shutdowns every 80 to 100 hours to clear the blockages.This need for frequent maintenance reduces operational efficiency and increases operating costs, in addition to posing safety risks due to pressure buildup in clogged pipes.

[0006] To mitigate these problems, the need to develop innovative solutions is evident. These solutions optimize the handling of pyrolysis gases from the pyrolysis reactor and reduce the frequency of interruptions by minimizing the accumulation and / or blockages caused by condensate hydrocarbons and rCB on the walls of the condensate system pipes. This would allow for a more continuous, cleaner, and more efficient operation of the condensate system.

[0007] DESCRIPTION

[0008] To overcome the drawbacks encountered, the present invention provides a system for cleaning and condensing gases from a pyrolysis reactor, as disclosed in claim 1. The invention aims to reduce the accumulation and / or obstruction caused by the adhesion of condensed hydrocarbons and rCB to the walls of the system's pipes.

[0009] Preferred embodiments of the aforementioned system are detailed in the dependent claims of claim 1.

[0010] According to a first embodiment, the pyrolysis gas cleaning and condensation system of a pyrolysis reactor, hereinafter referred to as the system, comprises:

[0011] a condensate tube provided for receiving the gases from the pyrolysis reactor, wherein in said condensate tube the gases are sprayed with a fluid to clean the gases of suspended black carbon residue (rCB) and to condense at least a portion of the hydrocarbons present in the gases; a first condenser configured to condense at least a portion of the hydrocarbons present in the gases coming from the condensate tube; and

[0012] a tank intended to receive the condensed hydrocarbons from the condensate tube and / or the first condenser, the rCB mixed with the fluid, as well as the gases from the first condenser, and is configured to separate the rCB from the fluid and form a mixture of condensed hydrocarbons with the fluid.

[0013] According to the above, in this embodiment, the system mainly comprises at least three elements, namely: the condensation tube, the first condenser, and the tank.

[0014] The condensation tube is configured for the expansion of gases from the reactor and for spraying them with a fluid. This spraying is carried out to, firstly, prevent the adhesion of rCB and, optionally, other products present in the gases to the walls; secondly, reduce the amount of rCB suspended in the gases; and thirdly, help to at least partially condense the hydrocarbons contained in the gases due to the relatively lower temperature of the spray fluid.

[0015] Alternatively, in one embodiment, the first condenser is a single-pass shell-and-tube type. This first condenser is configured to condense hydrocarbons present in the gases from the condensate tube. The first condenser utilizes the weight of the condensed hydrocarbons and the rCB mixed with the fluid on its walls to prevent accumulation and / or blockages.

[0016] In another alternative embodiment, the tank is configured to receive the condensate hydrocarbons from the condensate tube and / or the first condenser, the rCB mixed with the fluid, and the gases from both the condensate tube and the first condenser. It is located downstream of the condensate tube and the first condenser. The tank is configured to separate the rCB from the fluid by settling, allowing the rCB to be subsequently removed from the tank. Advantageously, the tank thus performs several functions simultaneously. First, it acts as a storage area for the condensate hydrocarbons from the condensate tube and / or the first condenser; second, it provides an area where the rCB can settle, enabling its removal from the system; and third, it acts as a conduit for gases with low or no hydrocarbon and rCB content for their subsequent disposal.

[0017] In another embodiment, the system comprises a second condenser configured to receive gases from either the storage tank and / or, alternatively, the first condenser. In the second condenser, the gases are further sprayed with the rCB cleaning fluid and the hydrocarbons remaining in the gases after their passage through the condensation tube and the first condenser are condensed. Alternatively, the condensed hydrocarbons and the rCB mixed with the fluid in the second condenser are directed to the storage tank. Advantageously, the incorporation of the second condenser allows for greater separation of hydrocarbons and rCB from the gases coming from the storage tank and / or the first condenser, resulting in a greater quantity of condensed hydrocarbons accumulated in the storage tank, a greater quantity of rCB that can be decanted in the storage tank, and gases with a lower quantity of condensable hydrocarbons and rCB.In this way, the gases treated in the second condenser will have a lower risk of forming accumulations and / or obstructions in the pipes through which they circulate.

[0018] Alternatively, in another embodiment, the condensation tube and / or the second condenser comprises a plurality of spiral-type nozzles configured to atomize the fluid. Advantageously, the spiral-type nozzles improve heat transfer between the gases and the fluid by atomizing the injected fluid through the nozzles.

[0019] In an alternative embodiment, the tank comprises two sections. In the first section, condensate hydrocarbons and rCB are collected mixed with the fluid, where the rCB settles out, forming sludge. In the second section, a mixture of condensate hydrocarbons and the fluid (free of rCB) is formed. The advantage of dividing the tank into these two sections is that each section allows for the accumulation and possible subsequent management of different byproducts extracted from the treated gases. Furthermore, the first section is configured so that the settled rCB can fall off by gravity as sludge, thus facilitating its subsequent disposal.

[0020] In another embodiment, the system comprises condensate management means configured to recirculate the mixture and use it as a fluid in the condensate tube and / or the second condenser. Alternatively, the management means include a heat exchanger to reduce the temperature of the mixture so that it can condense a greater quantity of hydrocarbons when used as a spray fluid. Advantageously, the management means allow for the recycling of at least a portion of the byproducts extracted from the gases, specifically the condensed hydrocarbon mixture and the fluid.

[0021] In one embodiment, the fluid is TPO pyrolytic oil. TPO pyrolysis oil can constitute between 40% and 50% by weight of the pyrolytic products, depending on the process and temperature. With a high percentage of these oils, if the system of the invention is applied to pyrolysis reactors for applications such as tire degradation, a significant quantity of TPO oil would be produced, allowing for high recirculation of these oils through spraying.

[0022] On the other hand, the invention also provides a procedural embodiment for cleaning and condensing gases from a pyrolysis reactor comprising the steps of:

[0023] - spraying the gases from the reactor with a fluid, capturing with said fluid any black carbon residue (rCB) suspended in said gases and at least partially condensing hydrocarbons present in the gases; - cooling the gases after spraying to condense the hydrocarbons present;

[0024] - separate the rCB from the fluid; mix the rCB-free fluid with the condensed hydrocarbons; and recirculate at least part of the mixture for use as a spray fluid for the gases coming from the reactor.

[0025] These stages allow for a high degree of cleaning of the gases from a pyrolysis reactor. Spraying with the fluid condenses hydrocarbons and removes rCB present in the gases. It also helps to push the condensed hydrocarbons and rCB mixed with the fluid. Subsequent cooling allows for further condensation of hydrocarbons present in the gases after spraying, resulting in more hydrocarbons accumulating in liquid form and a lower proportion of these condensed hydrocarbons in the treated gases. Separating the rCB mixed with the fluid then allows for the separate management of the two substances. The mixture of rCB-free fluid with condensed hydrocarbons forms a blend that can be recirculated and used for spraying.In this way, the importance of separating the rCB from the fluid can be appreciated on the one hand, and the advantage of using a fluid in the spray that can be mixed with the condensed hydrocarbons, thus taking advantage of the condensed hydrocarbons for subsequent recirculation.

[0026] In another embodiment of the process, an additional gas cooling stage is included to condense any remaining hydrocarbons. In this stage, the gases are further sprayed with the fluid that captures the remaining rCB. This additional stage increases hydrocarbon condensation and rCB removal from the gases, resulting in a higher quantity of condensed hydrocarbons and cleaned rCB, and producing gases with lower levels of these components.

[0027] Another embodiment of the procedure includes the following steps for separating rCB from the fluid: collecting the condensate hydrocarbons and the rCB mixed with the fluid, settling the rCB into sludge, and mixing the condensate hydrocarbons with the rCB-free fluid. This separation process takes advantage of the higher relative density of rCB compared to the condensate hydrocarbons and the fluid, configuring the process so that the rCB can settle at the collection point. Finally, the rCB-free fluids can be mixed with the condensate hydrocarbons to form a mixture that can be used in recirculation as the spray fluid.

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] The above and other advantages and features will be more fully understood from the following detailed description of some exemplary embodiments with reference to the accompanying drawings, which are to be considered illustrative and not limiting, in which:

[0030] Fig. 1 is a schematic drawing of the cleaning and condensation system of the invention.

[0031] Fig. 2 is a schematic drawing of the cleaning and condensation system with by-product management modules.

[0032] DETAILED DESCRIPTION OF AN IMPLEMENTATION EXAMPLE

[0033] The following detailed description presents numerous specific examples to provide a thorough understanding of the relevant teachings. However, it will be evident to those skilled in the subject that these teachings can be put into practice without such details.

[0034] As can be seen in Figures 1 and 2, the present invention provides a cleaning and condensation system (1) for pyrolysis gases from a pyrolysis reactor (100). The system (1) comprises a condensation tube (2) in fluid connection with the pyrolysis reactor (100). The gases from the pyrolysis reactor (100) expand in the condensation tube (2), at least partially condensing the hydrocarbons present in said gases. Furthermore, in the condensation tube (2), the gases are sprayed with a fluid (3) to at least partially condense the hydrocarbons present, secondly, to clean the gases of suspended rCB by capturing said rCB with the fluid, and thirdly, to move the condensed hydrocarbons and the rCB mixed with the fluid (3) that adheres to the walls of the condensation tube (2) so as to prevent its accumulation and possible obstruction.

[0035] Alternatively, bellows-type compensators (not shown) are provided at the inlet and outlet of the condensation tube (2), these compensators being configured to absorb the relative mechanical displacements due to thermal expansion.

[0036] In an alternative embodiment, the condensation tube (2) is dimensioned such that its longitudinal extension is less than its transverse extension, whereas in the case of a tube with a circular cross-section, its diameter is equal to or greater than its length, such that, with the spraying, it results in the utilization of the forces of the weight of the condensed hydrocarbons and of the rCB mixed with the fluid (3) adhering to the walls and the force of the spray in a substantially vertical direction, thus increasing the cleaning effect of the walls of the condensation tube (2).

[0037] The system (1) further comprises a first condenser (4) in fluid connection with the condensate tube (2), as shown in Figures 1 and 2. This first condenser (4) may be of the shell and tube type and is intended to cool the gases coming from the condensate tube (2). Its arrangement is substantially vertical so that the condensed hydrocarbons and the rCB mixed with the fluid (3) from the condensate tube (2) and the hydrocarbons condensed in the first condenser (4) are able to fall by gravity through it to a tank (5) located downstream of the first condenser (4).

[0038] In an alternative embodiment, the condensate tube (2) is inclined towards the first condenser (4) to facilitate the gravity flow at its lower part of the condensate hydrocarbons mixed with rCB.

[0039] The tank (5) is configured to perform several functions. First, it is configured to collect the condensed hydrocarbons from both the condensate tube (2) and the first condenser (4), the rCB mixed with the fluid (3) from the condensate tube (2), and, in addition, to receive the gases from the first condenser.

[0040] The condenser (4) is configured to allow the decantation of the rCB mixed with the fluid (3). To accumulate the decanted rCB, the tank (5) comprises an inclined base such that the rCB accumulates at the lowest point. Thirdly, the tank (5) is configured so that the fluid (3) and the condensed hydrocarbons can be mixed to form a mixture (6).

[0041] To generate said mixture (6) of fluid (3) and condensate hydrocarbons, the tank (5) is provided with a first wall (5.3) intended to divide the tank (5) into first and second sections (5.1, 5.2). In the first section (5.1), the rCB settles, and in the second section (5.2), the mixture (6) is formed by the overflow from the first section (5.1) to the second section (5.2) of the accumulated condensate hydrocarbons and the rCB mixed with the fluid (3).

[0042] To form a mixture (6) with fewer impurities, a second wall (5.4) is positioned at the top of the tank (5) between the fluid connection between the first condenser (4) and the tank (5) and the first wall (5.3). This second wall (5.4) has two main functions. First, it limits the amount of floating substances, facilitating the production of a mixture (6) with fewer impurities. Second, it redirects the gases from the first condenser (4) to a second condenser (7) so that a portion of the tank (5) does not come into contact with the gases from the first condenser (4), reducing hydrocarbon condensation and rCB deposition in that portion and thus reducing the need for cleaning.

[0043] Level sensors (not shown) are arranged in the tank (5) to prevent false readings due to fouling caused by the buildup of rCB, heavy hydrocarbons, or sludge. At least one of these sensors is located at the liquid level of the first section (5.1), while at least two sensors are arranged in the second section (5.2), below the overflow level of the first wall (5.3), to protect the pumps from running dry. Alternatively, the sensors are flat vibratory level switches. A second condenser (7) is in fluid connection with the tank (5) and is configured to cool and spray the gases from the tank (5) with fluid (3), as shown in Figures 1 and 2. This condenses more hydrocarbons and cleans the suspended rCB gases, producing gases with lower levels of these components.On the other hand, the fluid spray (3) enables the condensation of hydrocarbons and captures the rCB mixed with fluid (3) to prevent its adhesion to the walls of the second condenser (7) by moving them towards the tank (5), thus reducing the need to clean the walls of the second condenser (7). The substantially vertical arrangement of the second condenser (7) promotes the descent of the condensed hydrocarbons and the rCB mixed with fluid (3) by means of the weight of these substances and takes advantage of the force of the fluid spray (3) in a substantially vertical direction towards the tank (5) to enhance the cleaning of the walls of the second condenser (7).

[0044] As can be seen in Figures 1 and 2, the second section (5.2) of the tank (5) is fluidly connected to the condensate tube (2) and the second condenser (7) by means of management means (9) configured to recirculate the mixture (6) of condensed hydrocarbons and fluid for spraying into the condensate tube (2) and the second condenser (7). Preferably, the spraying into the condensate tube (2) and the second condenser (7) is carried out through spiral-type nozzles (8) that atomize the fluid (3), thereby improving heat transfer with the gases and the removal of suspended rCB.

[0045] In the preferred embodiment, the management means (9) comprise at least one pump (9.1) and at least one heat exchanger (9.2). The pump (9.1) provides the pressure required for spraying, and the heat exchanger (9.2) reduces the temperature of the sprayed fluid (3) to increase hydrocarbon condensation. In this way, the amount of recirculated TPO used in spraying is regulated by the pump (9.1). Depending on the amount of gas admitted to the system and its temperature, a greater or lesser amount of TPO is recirculated.

[0046] As can be seen in Figure 2, the second section (5.2) of the tank (5) is in fluid connection with a condensate hydrocarbon storage module (10) so that it can extract the condensate hydrocarbon mixture (6) with the fluid (3). The first section (5.1) of the tank (5) is in fluid connection with a sludge extraction module (11) at the lower part of the tank's sloping base (5) so that it can extract the settled rCB. The second condenser (7) is in fluid connection with a gas treatment module (12) so that the treated gases can be extracted. In this way, these three products—the condensate hydrocarbons, the sludge comprising the settled rCB, and the treated gases—can be subsequently managed.

Claims

CLAIMS 1. System (1) for cleaning and condensing pyrolysis gases from a pyrolysis reactor (100) comprising: a condensation tube (2) provided to receive the gases from the pyrolysis reactor (100), wherein in said condensation tube (2) the gases are sprayed with a fluid (3) to clean the gases of suspended black carbon residue rCB and to condense at least a portion of the hydrocarbons present in the gases; a first condenser (4) configured to condense at least a portion of the hydrocarbons present in the gases coming from the condensation tube (2); and a tank (5) intended to receive the condensed hydrocarbons from the condensate tube (2) and / or the first condenser (4), the rCB mixed with the fluid (3), as well as the gases from the first condenser (4), and is configured to separate the rCB from the fluid (3) and form a mixture (6) of condensed hydrocarbons with the fluid (3).

2. System (1) according to claim 1 comprising a second condenser (7) configured to receive the gases from the tank (5) and wherein in said second condenser (7) the gases are sprayed with the fluid (3) to clean the gases of rCB and condense at least a portion of the hydrocarbons present in the gases, wherein the condensed hydrocarbons and the rCB mixed with the fluid are stored in the tank (5).

3. System (1) according to any of the preceding claims wherein the condensation tube (2) and / or the second condenser (6) comprises a plurality of spiral-type nozzles (8) configured to spray the fluid (3).

4. System (1) according to any of the preceding claims wherein the tank (5) comprises two sections, wherein in a first section (5.1) the condensed hydrocarbons and the rCB mixed with the fluid are collected, in which the rCB is decanted forming sludge, and wherein in a second section (5.2) the mixture (6) of condensed hydrocarbons with the fluid is formed.

5. System (1) according to any of the preceding claims, or according to claim 3 or 4 when dependent on claim 2, comprising condensate management means (9) configured to recirculate the mixture (6) for use as fluid (3) in the condensate tube (2) and / or in the second condenser (7).

6. System (1) according to any of the preceding claims wherein the fluid (3) is TPO pyrolytic oil.

7. Procedure for cleaning and condensing gases from a pyrolysis reactor comprising the following steps: spraying the gases from the reactor with a fluid (3), capturing with said fluid (3) black carbon residues rCB suspended in said gases and at least partially condensing hydrocarbons present in the gases; cool the gases after spraying to condense the hydrocarbons present; separate the rCB from the fluid (3); mix the rCB-free fluid (3) with the condensed hydrocarbons; and recirculate at least a portion of the mixture (6) for use as fluid (3) for spraying the gases from the reactor.

8. A method according to claim 7 comprising an additional gas cooling step to condense the hydrocarbons still present in the gases, wherein said gases are further sprayed with the fluid (3) capturing the remaining rCB.

9. A method according to any of claims 7 or 8 wherein, for separating the rCB from the fluid (3), it comprises the steps of collect the condensed hydrocarbons and the rCB mixed with the fluid (3); decant the rCB forming sludge; and mix the condensed hydrocarbons with the rCB-free fluid (3).

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