Patent Description:
About <NUM>% of phenols used around the world are generally produced by a Hock process. The Hock process is carried out by three steps of: (<NUM>) alkylating benzene by propylene to form cumene, (<NUM>) binding the cumene with oxygen to oxidize cumene to cumene hydroperoxide (CHP), and (<NUM>) decomposing cumene hydroperoxide into phenol and acetone by an acid decomposition reaction in the presence of an acid catalyst.

Here, in step (<NUM>) of oxidizing cumene, by-product such as acetophenone (AP), dimethyl benzyl alcohol (DMBA), dicumyl peroxide (DCP), and dicumene (DC) are produced, in addition to cumene hydroperoxide.

In addition, in step (<NUM>) of acid decomposition reaction of cumene hydroperoxide, hydroxy acetone (HA), <NUM>-methylbenzofuran (<NUM>-MBF), α-methylstyrene (AMS), mesityl oxide (MO), an α-methylstyrene dimer (AMS dimer), cumylphenol (CP), and the like are produced as by-product, in addition to phenol and acetone.

Therefore, since a product stream produced by the reaction process described above is present in a state in which phenol, acetone, and various by-products are mixed, a series of separation processes for separating phenol from the product stream is required.

The product stream is introduced to a separate separation device, in which an acetone-based mixture including unreacted cumene, acetone, α-methylstyrene, hydroxyacetone, and the like is separated in the tower top of the separation device and a phenol-based mixture including phenol, a part of α-methylstyrene and <NUM>-methylbenzofuran, other by-products, and the like is separated in the tower bottom of the separation device.

The phenol-based mixture separated from the tower bottom of the separation device is introduced to a phenol column, in which phenol is separated in the tower top of the phenol column and phenol-based by-product such as dicumyl peroxide, cumylphenol, α-methylstyrene dimer, and tar are separated in the tower bottom of the phenol column.

In addition, in general, a process of producing bisphenol A (BPA) is a process of condensing phenol and acetone produced from the Hock process in the presence of an acidic catalyst or a cation exchange resin to produce bisphenol A.

Thus, unreacted phenol, unreacted acetone, trisphenol (BPX), tar, and the like are produced as by-products, in addition to bisphenol A, in the bisphenol A reaction product stream.

From the by-products produced in the phenol process and the bisphenol A preparation process, effective components such as phenol, cumene, and α-methylstyrene may be recovered by a separate decomposition device, and a study of the decomposition process and the decomposition device allowing efficient recovery of the effective components is in progress.

<CIT> discloses a method of decomposing phenol-based by-product, the method comprising: introducing a phenol-based by-product stream, a first stream of a side discharge stream from a decomposition device, and a process water stream to a mixing device and mixing the streams; introducing a discharge stream from the mixing device to a layer separation device to phase-separate the stream into an oil phase and an aqueous phase; introducing the oil stream to the decomposition device to carry out decomposition; and supplying the first stream of the side discharge stream from the decomposition device to the mixing device, and recovering effective components from an upper discharge stream from the decomposition device.

An object of the present invention is to provide a method which decomposes phenol-based by-product to obtain effective components and uses a side discharge stream from a decomposition device to reuse heat from the side discharge stream from the decomposition device in the process, thereby reducing energy.

In one general aspect, a method of decomposing phenol-based by-product includes: introducing a phenol-based by-product stream, a first stream of a side discharge stream from a decomposition device, and a process water stream to a mixing device and mixing the streams; introducing a discharge stream from the mixing device to a layer separation device to phase-separate the stream into an oil phase and an aqueous phase; passing an oil stream discharged from the layer separation device through any one or more of a first heat exchanger and a second heat exchanger and introducing the stream to the decomposition device to carry out decomposition; and supplying the first stream of the side discharge stream from the decomposition device to the mixing device, forming a mixed stream of a second stream of the side discharge stream with a lower discharge stream and discharging the mixed stream, and recovering effective components from an upper discharge stream from the decomposition device,.

According to the method of decomposing phenol-based by-product according to the present invention, when the phenol-based by-product are decomposed to obtain effective components, high value-added effective components from which salts are removed may be obtained, and also a side discharge stream from a decomposition device is utilized to reuse heat of the side discharge stream from the decomposition device, thereby reducing energy.

<FIG> are process flow diagrams for a method of decomposing phenol-based by-product disclosed, while <FIG> is a process flow diagrams for a method of decomposing phenol-based by-product according to an exemplary embodiment of the present invention, respectively.

<FIG> is a process flow diagram for a method of decomposing phenol-based by-product according to the comparative example.

In the present invention, the term "stream" may refer to a fluid flow in a process, or may refer to a fluid itself flowing in a pipe. Specifically, the "stream" may refer to both a fluid itself flowing in a pipe connecting each device and a fluid flow. In addition, the fluid may refer to a gas or a liquid.

Hereinafter, the present invention will be described in more detail with reference to the <FIG> for better understanding of the present invention.

According to the present invention, a method of decomposing phenol-based by-product is provided. The method of decomposing phenol-based by-product may include: introducing a phenol-based by-product stream, a first stream of a side discharge stream from a decomposition device <NUM>, and a process water stream to a mixing device <NUM> and mixing the streams; introducing a discharge stream from the mixing device <NUM> to a layer separation device <NUM> to phase-separate the stream into an oil phase and an aqueous phase; passing an oil stream discharged from the layer separation device <NUM> through any one or more of a first heat exchanger <NUM> and a second heat exchanger <NUM> and introducing the stream to the decomposition device <NUM> to carry out decomposition; and supplying the first stream of the side discharge stream from the decomposition device <NUM> to the mixing device <NUM>, forming a mixed stream of a second stream of the side discharge stream with a lower discharge stream and discharging the mixed stream, and recovering effective components from an upper discharge stream from the decomposition device,.

According to an exemplary embodiment of the present invention, the phenol-based by-product may include any one or more of phenol-based by-product produced in a phenol preparation process and phenol-based by-product produced in a bisphenol A preparation process. For example, the phenol-based by-product may be phenol-based by-product produced in the phenol preparation process, phenol-based by-product produced in the bisphenol A preparation process, or a mixture of the phenol-based by-product produced in the phenol preparation process and the phenol-based by-product produced in the bisphenol A preparation process.

The phenol preparation process may be carried out by the Hock process described above. Specifically, the phenol preparation process may be carried out by a step of decomposing and purifying cumene hydroperoxide prepared by an oxidation reaction of cumene to separate phenol and acetone. The step of decomposing and purifying cumene hydroperoxide prepared by the oxidation reaction of cumene to separate phenol and acetone is a step of using a cumene purification process and a phenol/acetone purification process. First, propylene and benzene are alkylated to prepare cumene and then heavy/light by-products are discharged by a purification process and cumene is purified and separated. Subsequently, the purified cumene is oxidized to prepare cumene hydroperoxide (CHP), the cumene hydroperoxide (CHP) is decomposed under a common acid catalyst such as sulfuric acid (H<NUM>SO<NUM>) to produce phenol, acetone, α-methylstyrene (AMS), and heavy by-products, and through a purification process, α-methylstyrene (AMS) and heavy by-products are discharged and phenol and acetone are purified and separated.

Since a product stream produced by the reaction process described above is present in a state in which phenol, acetone, and various by-products are mixed, a series of separation processes for separating phenol from the product stream is required.

The phenol-based mixture separated from the tower bottom of the separation device is introduced to a phenol column, in which phenol is separated in the tower top of the phenol column and phenol-based by-product such as dicumyl peroxide, cumylphenol, alpha-methylstyrene dimer, and tar are separated in the tower bottom of the phenol column. As a result, the phenol-based by-product produced from the phenol preparation process may include some effective components such as phenol, cumene, and α-methylstyrene, and tar.

In addition, the bisphenol A preparation process may be carried out by a method of reacting phenol and acetone prepared by the Hock process described above to prepare bisphenol A, and recovering bisphenol A from the reaction product. Specifically, the bisphenol A preparation process may be carried out by: decomposing and purifying cumene hydroperoxide prepared by an oxidation reaction of cumene to separate phenol and acetone; separating bisphenol A prepared by reacting the separated phenol and acetone and decomposing a stream including unseparated bisphenol A under an aqueous alkaline solution; and separating the reaction product by the decomposition reaction, phenol-based by-product, and acetone-based by-products.

The step of decomposing and purifying cumene hydroperoxide prepared by the oxidation reaction of cumene to separate phenol and acetone is a step of using a cumene purification process and a phenol/acetone purification process. First, propylene and benzene are alkylated to prepare cumene and then heavy/light by-products are discharged by a purification process and cumene is purified and separated. Subsequently, the purified cumene is oxidized to prepare cumene hydroperoxide (CHP), the cumene hydroperoxide (CHP) is decomposed under a common acid catalyst such as sulfuric acid (H<NUM>SO<NUM>) to produce phenol, acetone, α-methylstyrene (AMS), and heavy by-products, and through a purification process, α-methylstyrene (AMS) and heavy by-products are discharged and phenol and acetone are purified and separated.

The step of separating bisphenol A prepared by reacting the separated phenol and acetone and decomposing a stream including unseparated bisphenol A under an aqueous alkaline solution is a step of using a bisphenol A (BPA) purification process. First, the purified and separated phenol and acetone are reacted to prepare bisphenol A, more correctly crude bisphenol A, and then a crystallization process was carried out to prepare bisphenol A having an improved purity. Bisphenol A prepared as such is separated by a BPA purification process and by-products including unseparated bisphenol A are decomposed under an excessive amount of the aqueous alkaline solution having properties of a base such as NaOH, KOH, and LiOH.

In the step of separating the reaction product by the decomposition reaction, phenol-based by-product, and acetone-based by-products, the stream after the decomposition reaction may be supplied to a separation device to separate an acetone-based mixture in a tower top of the separation device and separate a reaction product in a tower bottom of the separation device. The reaction product is introduced to a bisphenol A/phenol column where bisphenol A is separated in the tower top, and phenol-based by-product such as bisphenol A, phenol, dicumyl peroxide, cumylphenol, an α-methylstyrene dimer, and tar are separated in the tower bottom. Here, the phenol-based by-product include bisphenol A which is a product, and effective components such as cumene and α-methylstyrene, in addition to tar which is an impurity.

As a result, the phenol-based by-product produced from the bisphenol A preparation process may include some effective components such as phenol, cumene, and α-methylstyrene, and tar, with bisphenol A.

Therefore, a mixture of the phenol-based by-product produced in the bisphenol A preparation process and phenol-based by-product produced in the phenol preparation process may include one or more selected from the group consisting of bisphenol A, phenol, α-methylstyrene, acetophenone, cumylphenol, and an α-methylstyrene dimer. As a specific example, the phenol-based by-product may include two or more selected from the group consisting of bisphenol A, phenol, α-methylstyrene, acetophenone, cumylphenol, and an α-methylstyrene dimer, or all of them.

The phenol-based by-product may include the phenol-based by-product produced in the bisphenol A preparation process and the phenol-based by-product produced in the phenol preparation process at a flow rate ratio of <NUM>:<NUM> to <NUM>. For example, the phenol-based by-product may include the phenol-based by-product produced in the bisphenol A preparation process and the phenol-based by-product produced in the phenol preparation process at a flow rate ratio of <NUM>:<NUM> to <NUM>, <NUM>:<NUM> to <NUM>, or <NUM>:<NUM> to <NUM>. As such, it may be preferred to decompose phenol-based by-product having a high content of the phenol-based by-product produced in the phenol preparation process relative to the phenol-based by-product produced in the bisphenol A preparation process, in terms of preventing a load on the decomposition device <NUM> and reducing an amount of energy used in the process.

According to an exemplary embodiment of the present invention, the phenol preparation process and the bisphenol A preparation process may be carried out by including the acid decomposition reaction of cumene hydroperoxide described above. Here, since the acid decomposition reaction of cumene hydroperoxide is carried out by including an acid, an acid decomposition reaction solution includes an acid. Therefore, in order to obtain phenol and acetone by a process such as distillation from the acid decomposition reaction solution, a process of neutralizing the acid decomposition reaction solution is needed.

Thus, the acid decomposition reaction solution is neutralized by an aqueous basic solution before being separated, where in the neutralized acid decomposition reaction solution, salts from a reaction between an acid used in the acid decomposition reaction and a base such as an aqueous basic solution are produced. The acid decomposition reaction solution neutralized by a neutralization process is separated into an oil phase and an aqueous phase and a separation process for obtaining phenol and acetone from the separated oil phase is carried out, and most of the salts are removed with the aqueous phase, but some salts remain in the oil phase.

The salts remain in the phenol-based by-product described in the present invention. The salts remaining in the phenol-based by-product as such causes corrosion, occlusion, and deposition of the decomposition device <NUM> during the decomposition of the phenol-based by-product for obtaining effective components from the phenol-based by-product, thereby resulting in device failure. Therefore, during the decomposition of the phenol-based by-product, it is important to minimize salts in the phenol-based by-product.

Thus, as a method for removing salts in the phenol-based by-product, a process water is introduced before decomposing the phenol-based by-product, to remove the salts, may be considered, but in this case, phase separation of the oil phase and the aqueous phase is not carried out well, and thus, the salts may not be sufficiently removed.

In addition, a method of introducing an organic material such as cumene and α-methylstyrene discharged as an effective component from an acetone column and the like in the phenol preparation process together with the process water to the phenol-based by-product, thereby removing salts, may be considered, but in this case, since cumene and α-methylstyrene should be obtained as a product again, an overload occurs in the phenol preparation process and the entire operation energy is increased.

In addition, a method of introducing an organic material such as an upper discharge stream of the decomposition device <NUM> including effective components for decomposing the phenol-based by-product to the phenol-based by-product with the process water, thereby removing salts, may be considered, but since the method uses the upper discharge stream of the decomposition device <NUM> obtained as effective components as it is, purification efficiency is decreased and the stream to be refluxed is decreased, so that cooling/heating for operating a condenser is further needed in the upper portion of the decomposition device <NUM>, resulting in an increase in overall operation energy. However, according to the method of decomposing phenol-based by-product according to the present invention, it is possible to minimize salts in the phenol-based by-product, and thus, it is possible to stably operate the phenol-based by-product decomposition device <NUM>, and the phenol-based by-product may be decomposed to effectively obtain effective components.

Specifically, in the present invention, as a method of removing salts in the phenol-based by-product, before decomposing the phenol-based by-product, the phenol-based by-product stream is supplied to a mixing device <NUM>, and the side discharge stream from the decomposition device <NUM> and a process water stream are introduced separately to the mixing device <NUM>, thereby minimizing salts remaining the phenol-based by-product. Here, as the side discharge stream from the decomposition device <NUM> supplied to the mixing device <NUM>, a first stream which is a part of the side discharge stream of the decomposition device <NUM> may be supplied.

The phenol-based by-product may include one or more selected from the group consisting of bisphenol A, phenol, α-methylstyrene, acetophenone, cumylphenol, and an α-methylstyrene dimer, as described above. As a specific example, the phenol-based by-product may include two or more selected from the group consisting of bisphenol A, phenol, α-methylstyrene, acetophenone, cumylphenol, and an α-methylstyrene dimer, or all of them.

The process water is for dissolving salts in the phenol-based by-product stream therein and removing the salts, and may mean including all various aqueous solutions such as an acidic aqueous solution and a basic aqueous solution, in addition to distilled water.

The process water may have a pH of <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, and within the range, corrosion of the mixing device <NUM> and the layer separation device <NUM> is prevented, solubility of the salts is improved, and phase separation ability in separation of an oil phase and an aqueous phase in the layer separation device <NUM> may be improved.

The mixing device <NUM> may be a mixer for mixing the phenol-based by-product and the process water. As a specific example, the mixer may be provided with a line mixer or a static mixer for easily carrying out mixing of the phenol-based by-product and the process water.

The side discharge stream from the decomposition device <NUM> is a stream discharged from the side of the decomposition device <NUM> described later, and may include one or more selected from the group consisting of phenol, acetophenone, isopropylphenol, α-methylstyrene, and cumene. As a specific example, the side discharge stream from the decomposition device <NUM> may include phenol, acetophenone, isopropylphenol, α-methylstyrene, and cumene. The reason why the side discharge stream from the decomposition device <NUM> is introduced to the mixing device <NUM> is that acetophenone included in the side discharge stream from the decomposition device <NUM> activates phase separation of an oil phase and an aqueous phase including salts in the phase separation using the layer separation device <NUM> described later, thereby minimizing salts remaining in the oil phase.

According to an exemplary embodiment of the present invention, the phenol-based by-product are a stream supplied from any one process of the phenol preparation process and the bisphenol A preparation process, and a supplied temperature may be high, for example, in a range of <NUM> or higher, <NUM> to <NUM>, or <NUM> to <NUM>. Therefore, in order to prevent vaporization of the process water before supplying the phenol-based by-product stream to the mixing device <NUM>, the phenol-based by-product stream may be cooled. Specifically, the phenol-based by-product stream may be cooled using a separate cooler <NUM> and then supplied to the layer separation device <NUM>. In addition, the phenol-based by-product stream may be cooled by being passed through a first heat exchanger <NUM>, before being cooled in the cooler <NUM>. Specifically, the phenol-based by-product stream is cooled by heat exchange with the oil stream discharged from the layer separation device <NUM> described later in the first heat exchanger <NUM>, and then, may be further cooled in the cooler <NUM>. As such, energy for cooling the phenol-based by-product stream may be reduced by the heat exchange with the stream in the process, and simultaneously, the oil stream discharged from the layer separation device <NUM> is heated before being supplied to the decomposition device <NUM>, thereby reducing energy used in the decomposition device <NUM>.

The phenol-based by-product stream may be introduced to the mixing device <NUM> with the first stream of the side discharge stream from the decomposition device <NUM> and the process water stream and be mixed therewith. For example, the phenol-based by-product stream and the first stream of the side discharge stream from the decomposition device <NUM> may be mixed before being cooled in the cooler <NUM> and be cooled by the cooler <NUM>, and after being cooled, may be introduced to the mixing device <NUM> and be mixed with the process water introduced to the mixing device <NUM>.

The phenol-based by-product stream, the first stream of the side discharge stream from the decomposition device <NUM>, and the process water stream, which are introduced to the mixing device <NUM>, may be <NUM>:<NUM> to <NUM>:<NUM> to <NUM>, <NUM>:<NUM> to <NUM>:<NUM> to <NUM>, or <NUM>:<NUM> to <NUM>:<NUM> to <NUM>. By controlling the flow rate ratio of the phenol-based by-product stream, the first stream of the side discharge stream from the decomposition device <NUM>, and the process water stream to the above range, not only the mixing of the phenol-based by-product stream, the first stream of the side discharge stream from the decomposition device <NUM>, and the process water stream but also the phase separation ability of the oil phase and the aqueous phase in the layer separation device <NUM> described later is improved, and removal efficiency of salts included in the phenol-based by-product is improved.

According to an exemplary embodiment of the present invention, a discharge stream from the mixing device <NUM> which is discharged from the mixing device <NUM> is supplied to the layer separation device <NUM>, and may be phase-separated into the oil phase and the aqueous phase in the layer separation device <NUM>. Specifically, in the layer separation device <NUM>, the discharge stream from the mixing device <NUM> may be phase-separated into the oil phase and the aqueous phase, for removing salts included in the discharge stream from the mixing device <NUM> and introducing the stream to the decomposition device <NUM>.

The oil stream discharged from the layer separation device <NUM> is a stream obtained by removing salts from the phenol-based by-product stream and may be used as a supply stream to the decomposition device <NUM>, and the oil stream discharged from the layer separation device <NUM> is in a state of having a minimized content of salts, and thus, may prevent corrosion, occlusion, deposition, and the like of the decomposition device <NUM> in the decomposition reaction of the decomposition device <NUM>.

The aqueous stream discharged from the layer separation device <NUM> may include salts remaining in the phenol-based by-product and the process water. Accordingly, salts may be removed from the phenol-based by-product stream.

A part of the stream of the aqueous stream discharged from the layer separation device <NUM> may be supplied to the mixing device <NUM> and be reused. In addition, of the aqueous stream discharged from the layer separation device <NUM>, the remaining stream which has not been supplied to the mixing device <NUM> may be discharged as waste water including salts.

The layer separation device <NUM> may be a drum for phase-separating the oil phase and the aqueous phase.

For phase-separating the oil phase and the aqueous phase from the layer separation device <NUM>, a step of retaining the discharge stream from the mixing device <NUM> in the layer separation device <NUM> for <NUM> hour to <NUM> hours, <NUM> hours to <NUM> hours, or <NUM> hours to <NUM> hours, may be included. As such, when the stream discharged from the mixing device <NUM> is retained in the layer separation device <NUM>, phase separation may occur more clearly, and thus, salts may be removed as much as possible from the phenol-based by-product.

The oil stream discharged from the layer separation device <NUM> may be supplied to the decomposition device <NUM> for a decomposition reaction. Here, the oil stream discharged from the layer separation device <NUM> may be heated using the stream in the process before being supplied to the decomposition device <NUM>, while being passed through any one or more of the first heat exchanger <NUM> and the second heat exchanger <NUM>. For example, the oil stream discharged from the layer separation device <NUM> may be heated using the phenol-based by-product stream while being passed through the first heat exchanger <NUM>, heated using a mixed stream of the second stream of the side discharge stream from the decomposition device <NUM> described later and the lower discharge stream while being passed through the second heat exchanger <NUM>, or is heated secondly while being passed through both the first heat exchanger <NUM> and the second heat exchanger <NUM>. As a result, the oil stream discharged from the layer separation device <NUM> is supplied to the decomposition device <NUM> after being heated using the stream in the process while being passed through any one or more of the first heat exchanger <NUM> and the second heat exchanger <NUM>.

According to an exemplary embodiment of the present invention, decomposition carried out in the decomposition device <NUM> may be thermal decomposition, and the decomposition device <NUM> for carrying out this may be a thermal cracker. As a specific example, the thermal cracker may be a reactor-distillation tower integrated separation device.

The effective components are separated from the upper portion of the decomposition device <NUM>, and for effectively separating a heavy material including tar from the lower portion, the decomposition device <NUM> may be operated at a temperature of <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> and a pressure of <NUM> bar to <NUM> bar, <NUM> bar to <NUM> bar, or <NUM> bar to <NUM> bar.

In the decomposition device <NUM>, the effective components may be separated from the upper discharge stream. The effective components may include one or more selected from the group consisting of, for example, phenol, α-methylstyrene, and cumene. In addition, the lower discharge stream from the decomposition device <NUM> is a stream including tar, and may be recovered and reused as a fuel and the like.

The side discharge stream from the decomposition device <NUM> may be discharged at <NUM>% to <NUM>%, <NUM>% to <NUM>%, or <NUM>% to <NUM>% of the total number of stages of the decomposition device <NUM>. In this case, acetophenone discharged to the upper discharge stream from the decomposition device <NUM> may be significantly reduced.

The side discharge stream from the decomposition device <NUM> may include <NUM> wt% or more of acetophenone. For example, the side discharge stream from the decomposition device <NUM> may include <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% of acetophenone. The acetophenone is an organic material included in the phenol-based by-product stream, and since it acts as an impurity in contrast to the effective components obtained by the phenol-based by-product decomposition reaction, it is preferred to minimize the content of acetophenone in the effective components. Therefore, when according to the present invention, the side discharge stream from the decomposition device <NUM> includes <NUM> wt% or more of acetophenone, the side discharge stream from the decomposition device <NUM> may be separated to minimize the content of acetophenone in the effective components obtained by the phenol-based by-product decomposition reaction, and thus, it is advantageous for obtaining the effective components.

The side discharge stream from the decomposition device <NUM> may branch to a first stream and a second stream. For example, the first stream of the side discharge stream from the decomposition device <NUM> is supplied to the mixing device <NUM> to improve salt removal efficiency in the phenol-based by-product stream and the second stream is passed through the second heat exchanger <NUM> and discharged, whereby pollutants accumulated in the second heat exchanger <NUM> may be dissolved and removed while the oil stream discharged from the layer separation device <NUM> is heated and the flowability of the lower discharge stream from the decomposition device <NUM> is improved.

Specifically, as described above, the first stream of the side discharge stream from the decomposition device <NUM> having a high content of acetophenone may be used to effectively remove salts included in the phenol-based by-product stream.

In addition, the second stream of the side discharge stream from the decomposition device <NUM> may be used to improve the flowability of the lower discharge stream from the decomposition device <NUM> having a high content of tar to have bad flowability. The lower discharge stream from the decomposition device <NUM> is mixed with the second stream to form a mixed stream, and the mixed stream is passed through the second heat exchanger <NUM> to be discharged. Thus, since the viscosity of the lower discharge stream from the decomposition device <NUM> may be lowered to improve flowability, and simultaneously, the organic material included in the side discharge stream from the decomposition device <NUM> has a composition, a temperature, and the like appropriate for dissolving pollutants accumulated in the heat exchanger, for example, a tar component, the pollutants accumulated in the inner wall, the pipe, and the like of the heat exchanger may be effectively dissolved within a short time to be removed.

In addition, since the decomposition device <NUM> is operated at a high temperature, the side discharge stream is also discharged at a high temperature, and the second stream of the side discharge stream from the decomposition device <NUM> at a high temperature is used as a heat source for heating the stream in the process, thereby reducing energy. For example, the temperature of the side discharge stream from the decomposition device <NUM> may be <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>. As such, the second stream of the side discharge stream from the decomposition device <NUM> at a high temperature is passed through the second heat exchanger <NUM> with the lower discharge stream from the decomposition device <NUM> and discharged, thereby improving the flowability of the lower discharge stream from the decomposition device <NUM> and also heating the oil stream of the layer separation device <NUM> which has been passed through the first heat exchanger <NUM> supplied to the second heat exchanger <NUM>.

According to an exemplary embodiment of the present invention, in the method of decomposing phenol-based by-product, if necessary, devices such as a distillation column (not shown), a condenser (not shown), a reboiler (not shown), a valve (not shown), a pump (not shown), a separator (not shown), and a mixer (not shown) may be further installed.

Hereinabove, the method of decomposing phenol-based by-product according to the present invention has been described and illustrated in the drawings, but the description and the illustration in the drawings are the description and the illustration of only core constitutions for understanding of the present invention, and in addition to the process and apparatus described above and illustrated in the drawings, the process and the apparatus which are not described and illustrated separately may be appropriately applied and used for carrying out the method of decomposing phenol-based by-product according to the present invention.

Hereinafter, the present invention will be described in more detail by the Examples. However, the following Examples are provided for illustrating the present invention. It is apparent to a person skilled in the art that various modifications and alterations may be made without departing from the scope and spirit of the present invention, and the scope of the present invention is not limited thereto. Examples <NUM> and <NUM> do not form part of the invention.

Referring to the process flow diagram illustrated in <FIG>, the process was simulated, using an Aspen Plus simulator from Aspen Technology, Inc. Specifically, a phenol-based by-product stream having the composition shown in the following Table <NUM> having a flow rate of <NUM>,<NUM>/hr was passed through a first heat exchanger <NUM> at a temperature of <NUM>, mixed with a first stream of a side discharge stream from a decomposition device <NUM>, supplied to a mixing device <NUM> in a state of being cooled to <NUM> by passing the stream through a cooler <NUM>, and mixed with a process water stream at pH <NUM> in the mixing device <NUM>. A flow ratio of the phenol-based by-product stream: the first stream of the side discharge stream from the decomposition device <NUM>: the process water stream was controlled to <NUM>:<NUM>:<NUM>, based on <NUM>,<NUM>/hr of the phenol-based by-product stream.

A discharge stream from the mixing device <NUM> was supplied to a layer separation device <NUM> and retained for <NUM> hours in the layer separation device <NUM>, and an oil stream discharged therefrom was supplied to the decomposition device <NUM> operated at <NUM> in a state of being heated to <NUM> by passing the stream through the first heat exchanger <NUM>.

Effective components were obtained from the upper discharge stream from the decomposition device <NUM>, the first stream of the side discharge stream discharged at <NUM> was supplied to the mixing device <NUM>, and the second stream was mixed with the lower discharge stream and discharged.

The compositions of the upper discharge stream and the side discharge stream from the decomposition device <NUM> are shown in the following Table <NUM>.

Referring to the process flow diagram illustrated in <FIG>, the process was simulated, using an Aspen Plus simulator from Aspen Technology, Inc. Specifically, a phenol-based by-product stream having the composition shown in Table <NUM> having a flow rate of <NUM>,<NUM>/hr was mixed with a first stream of a side discharge stream from a decomposition device <NUM> at a temperature of <NUM>, supplied to a mixing device <NUM> in a state of being cooled to <NUM> by passing the stream through a cooler <NUM>, and mixed with a process water stream at pH <NUM> in the mixing device <NUM>. A flow ratio of the phenol-based by-product stream: the first stream of the side discharge stream from the decomposition device <NUM>: the process water stream was controlled to <NUM>:<NUM>:<NUM>, based on <NUM>,<NUM>/hr of the phenol-based by-product stream.

The discharge stream from the mixing device <NUM> was supplied to a layer separation device <NUM> and retained for <NUM> hours in the layer separation device <NUM>, and an oil stream discharged therefrom was supplied to the decomposition device <NUM> operated at <NUM> in a state of being heated to <NUM> by passing the stream through the second heat exchanger <NUM>.

Effective components were obtained from the upper discharge stream from the decomposition device <NUM>, the first stream of the side discharge stream discharged at <NUM> was supplied to the mixing device <NUM>, and the second stream was mixed with the lower discharge stream and passed through the second heat exchanger <NUM> to be discharged.

Referring to the process flow diagram illustrated in <FIG>, the process was simulated, using an Aspen Plus simulator from Aspen Technology, Inc. Specifically, a phenol-based by-product stream having the composition shown in Table <NUM> having a flow rate of <NUM>,<NUM>/hr was passed through a first heat exchanger <NUM> at a temperature of <NUM>, mixed with a first stream of a side discharge stream from a decomposition device <NUM>, supplied to a mixing device <NUM> in a state of being cooled to <NUM> by passing the stream through a cooler <NUM>, and mixed with a process water stream at pH <NUM> in the mixing device <NUM>. A flow ratio of the phenol-based by-product stream: the first stream of the side discharge stream from the decomposition device <NUM>: the process water stream was controlled to <NUM>:<NUM>:<NUM>, based on <NUM>,<NUM>/hr of the phenol-based by-product stream.

The discharge stream from the mixing device <NUM> was supplied to a layer separation device <NUM> and retained for <NUM> hours in the layer separation device <NUM>, and an oil stream discharged therefrom was supplied to the decomposition device <NUM> operated at <NUM> in a state of being heated to <NUM> by passing the stream through the first heat exchanger <NUM> and the second heat exchanger <NUM>.

Referring to the process flow diagram illustrated in <FIG>, the process was simulated, using an Aspen Plus simulator from Aspen Technology, Inc. Specifically, a phenol-based by-product stream having the composition shown in Table <NUM> at a temperature of <NUM> was cooled to <NUM> using a cooler <NUM> at a flow rate of <NUM>,<NUM>/hr, and then supplied to a mixing device <NUM> with a process water stream at pH <NUM>. A flow ratio of the phenol-based by-product stream: the process water stream introduced to the mixing device <NUM> was controlled to <NUM>:<NUM>, based on <NUM>,<NUM>/hr of the phenol-based by-product stream.

The discharge stream from the mixing device <NUM> was supplied to a layer separation device <NUM> and retained for <NUM> hours in the layer separation device <NUM>, and an oil stream discharged therefrom was supplied to the decomposition device <NUM> operated at <NUM>.

The effective components were obtained from the upper discharge stream from the decomposition device <NUM>, and the lower discharge stream was discharged.

Temperature (°C) of the oil streams discharged from the layer separation device <NUM> supplied to the decomposition layer <NUM> and amounts of energy used (Gcal/hr) in each process of Examples <NUM> to <NUM> and Comparative Example <NUM> are shown in the following Table <NUM>.

Referring to Table <NUM>, in Examples <NUM> to <NUM> in which the oil stream discharged from the layer separation device <NUM> was heated using any one or more of the phenol-based by-product and the mixed stream of the second stream of the side discharge stream and the lower discharge stream from the decomposition device <NUM>, it was confirmed that the amount of energy used in the process was decreased. In particular, in Example <NUM> in which the oil stream discharged from the layer separation device <NUM> was heated using the phenol-based by-product stream in the first heat exchanger <NUM> and the oil stream heated in the first heat exchanger <NUM> was further heated using a mixed stream of the second stream of the side discharge stream and the lower discharge stream in the second heat exchanger <NUM>, it was confirmed that the amount of energy used was decreased the most.

Claim 1:
A method of decomposing phenol-based by-product, the method comprising:
introducing a phenol-based by-product stream, a first stream of a side discharge stream from a decomposition device, and a process water stream to a mixing device and mixing the streams;
introducing a discharge stream from the mixing device to a layer separation device to phase-separate the discharge stream into an oil phase and an aqueous phase;
passing an oil stream discharged from the layer separation device through any one or more of a first heat exchanger and a second heat exchanger and introducing the oil stream to the decomposition device to carry out decomposition; and
supplying the first stream of the side discharge stream from the decomposition device to the mixing device, forming a mixed stream of a second stream of the side discharge stream from the decomposition device with a lower discharge stream from the decomposition device and discharging the mixed stream, and recovering effective components from an upper discharge stream from the decomposition device,
wherein the phenol-based by-product stream is supplied to the mixing device after heat exchange with the oil stream discharged from the layer separation device in the first heat exchanger, and
wherein the mixed stream is heat-exchanged with the oil stream, which has been passed through the first heat exchanger, in the second heat exchanger and then is discharged.