JP2013184948A - Method of purifying crude aromatic dicarboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect steam occurring during a crystallizing process as thermal energy and condensed water, and then effectively use it by circulating it within a producing process, in producing a purified aromatic dicarboxylic acid by hydropurifying a crude aromatic dicarboxylic acid.SOLUTION: In a heating and dissolving step (I) of heating and dissolving a crude aromatic dicarboxylic acid crystal slurry with a plurality of heat exchangers by using water vapor occurring due to a gradual pressure discharge from a crystallization chamber in a crystallizing step (IV), each of the plurality of heat exchangers is provided with a flush drums that collects condensed water. An efficient heat recovery system is constructed with a heating system as heating units (a heating unit and a deformed heating unit), wherein the heating system includes the flow of the water vapor of a heated water vapor-introducing line 12, a heat exchanger H-N, a flash drum B-N, a water vapor-circulating line 13, an excess water vapor-discharging line 14, and a condensed water-transporting lines 15.

Description

  The present invention relates to a method for producing a purified aromatic dicarboxylic acid by hydrorefining a crude aromatic dicarboxylic acid.

  Crude aromatic dicarboxylic acids (crude terephthalic acid, crude isophthalic acid, etc.) are liquid phase oxidized with dioxybenzene (paraxylene, metaxylene, etc.) as starting materials in an acetic acid solvent in the presence of an oxidation catalyst and an oxygen-containing gas. It is mainly manufactured by.

  The produced crude aromatic dicarboxylic acid crystals are mixed with solvent water to form a slurry, heated to a high-temperature and high-pressure aqueous solution, and then into a purified aqueous solution through a hydrotreating catalyst layer in the presence of a hydrogen-containing gas. . Further, a purified aromatic dicarboxylic acid crystal slurry is produced through a crystallization step in which the pressure is lowered stepwise and cooled by releasing pressure. The purified aromatic dicarboxylic acid crystal slurry is subjected to solid-liquid separation to recover a crystal component, followed by a drying step to produce purified aromatic dicarboxylic acid (purified terephthalic acid crystal powder, purified isophthalic acid crystal powder, etc.). To. The purified aromatic dicarboxylic acid thus obtained (high-purity aromatic dicarboxylic acid) is widely used in large quantities as a raw material for producing polyester for fibers, films, bottles and the like.

  In the production method of the purified aromatic dicarboxylic acid, a large amount of solvent water (about 1.5 to 10 times by weight) is required to make the crude aromatic dicarboxylic acid crystal into a slurry, and further the crude aromatic dicarboxylic acid crystal slurry is dissolved. In order to obtain an aqueous solution, heat energy for heating to a high temperature of about 180 ° C. (vapor pressure of about 1 MPa) to about 300 ° C. (vapor pressure of about 9 MPa) is required under high pressure.

  On the other hand, the aqueous solution of the crude aromatic dicarboxylic acid crystal slurry is purified by the catalyst layer in the presence of hydrogen, and then, in the crystallization step of precipitating purified dicarboxylic acid crystals, the pressure is reduced stepwise, Since it is cooled to ~ 170 ° C (water vapor pressure 0.1 to 0.8 MPa), a large amount of steam is generated.

  For this reason, several methods have been proposed in which the steam generated as a result of the pressure release in the crystallization process of the purified aromatic dicarboxylic acid is used as a heat source for the thermal energy required for the heating and dissolving process of the crude aromatic dicarboxylic acid crystal slurry. Yes.

  Patent Document 1 is a method in which high-temperature water vapor generated in the crystallization step is directly introduced into a supply flow of a crude terephthalic acid crystal slurry and heated. However, the pressure of the high-temperature steam generated by the release pressure in the crystallization process is lower than the pressure of the feed slurry flow, which is a problematic method for direct introduction.

  Moreover, in patent document 2, the refined terephthalic acid crystal grain diameter produced | generated from a crystallization process is adjusted, and the high temperature water vapor | steam generate | occur | produced by the release pressure in the 1st crystallization tank of the crystallization process is made into crude It has been proposed to be used as heat energy for heating and dissolution by exchanging heat with terephthalic acid crystal slurry. In that case, a method of using the generated steam from the crystallization tanks for heating each heat exchanger and using the steam or condensate obtained at each temperature together for heating the supply slurry is exemplified as a flow. (Fig. 4).

  In Patent Document 3, water vapors of different pressures generated from the respective crystallization tanks are introduced into the heat exchangers at the respective temperatures for heating the heat exchangers, and the high temperatures generated by heating the heat exchangers on the high temperature side, respectively. A condensing water is supplied to each heat exchanger together with the introduced steam, and a heating and melting process is proposed in which the supplied slurry is heated. However, in this heating method, the high-pressure steam for heating introduced into the heat exchanger and the high-temperature and high-pressure condensate are mixed and introduced at the same time, so there are practical problems in terms of fluidity and heat transfer efficiency of the heating medium. There is a way.

  In Patent Document 4, in the hydrorefining method of crude terephthalic acid, the condensed water in the heating and dissolving step produced after using water vapor generated by the pressure released from the crystallization step as a heat source is mixed with the crude aromatic dicarboxylic acid crystal. Thus, it has been proposed that it can be used as a part of water for preparing a slurry, and a method for adjusting the solvent water used for preparing the slurry. However, the vapor generated from the crystallization process is mixed with about 500 to 1500 ppm of paratoluic acid, which is an impurity. Therefore, there is a quantitative limitation (condensed water: pure water = 100: 300 to 500) to use the generated condensed water directly as solvent water, and processing steps such as distillation and membrane separation to reduce the content of p-toluic acid. I have a proposal that requires.

Special table hei 7-507292 JP-A-8-225489 JP 2007-261957 A JP 2004-231644 A

  The present invention is intended to solve the above-mentioned problems of the prior art, and is generated from each crystallization tank in the crystallization step in the production of purified aromatic dicarboxylic acid by hydrorefining crude aromatic dicarboxylic acid. To construct a practical heat-dissolving system that uses stable steam and heat recovery for each heat exchanger in the heat-dissolution process of crude aromatic dicarboxylic acid crystal slurry using stable pressure and heat recovery. Was the first issue.

  And it made it the 2nd subject to use the condensed water produced | generated and flowed out from this heating melt | dissolution system as a part of aqueous medium which prepares a crude aromatic dicarboxylic acid crystal slurry.

  The object of the present invention was to reduce the production cost by collecting and circulating the heat and aqueous medium in the production of the purified aromatic dicarboxylic acid by combining the above two problems.

  In general, the continuous production of purified aromatic dicarboxylic acid is carried out by using crude aromatic dicarboxylic acid crystals as a crude aromatic dicarboxylic acid crystal slurry using about 1.5 to 10 times, preferably 2 to 5 times, solvent water, and under pressure. Is supplied to a plurality of serially connected heat exchangers (multi-tubular heat exchangers), heated in order until the temperature reaches about 180 to 300 ° C. (temperature of the hydrorefining reaction), and then through the dissolution tank, the crude aromatic dicarboxylic acid An acid aqueous solution is obtained. At that time, in the heat exchanger, the crude aromatic dicarboxylic acid crystal slurry to be heated is usually passed through the tube side, and the water vapor to be heated is passed through the shell side.

  In the heat exchanger (multitubular heat exchanger), the crude aromatic dicarboxylic acid crystal slurry to be supplied passes through the liquid flow at a high speed (about 1.5m / sec or more) under pressure, while the shell side The hot water vapor introduced under pressure releases condensed latent heat and becomes condensed water. The high-temperature and high-pressure condensed water is discharged from the heat exchanger.

  In the crystallization process, a purified aromatic dicarboxylic acid aqueous solution of about 180 to 300 ° C (about 1.0 to 9MPa) is required from atmospheric pressure to the set pressure of the final crystallization tank of about 0.8MPa (about 100 to 170 ° C). Depending on the pressure, the pressure is gradually reduced to a crystallization tank in which the pressure is gradually reduced (steps 4 to 6) until the pressure becomes lower than atmospheric pressure (about 50 ° C.). Therefore, water vapor having a temperature corresponding to the pressure is generated and discharged from each crystallization tank.

Therefore, the present inventors introduced water vapor generated from each crystallization tank to the heating side (shell side) of each heat exchanger corresponding to the temperature of the crude aromatic dicarboxylic acid crystal slurry to be heated, A heat exchange system has been devised that stably draws out heat transfer using only the latent heat of condensation of water vapor.
At the same time, a method for recovering the thermal energy (condensation latent heat) of the generated steam as condensed water having a relatively low temperature near atmospheric pressure was examined.

  As a result, the present inventors supplied steam generated from the crystallization tank to the heat exchanger, and the unit (heating unit 32) was a steam heating mechanism (range of thin dotted lines in FIG. 1) integrated with the attached flash drum. A steam heating system of crude aromatic dicarboxylic acid crystal slurry was constructed. The first means for solving the problem is to use the heating and melting step of the crystal slurry in which the heating unit into which water vapor from each crystallization tank of the crystallization step is sequentially introduced is configured.

  First, the outline of the purification method of the crude aromatic dicarboxylic acid of this invention is demonstrated using FIG. In addition, the code | symbol attached | subjected to each name below serves for invention understanding with reference to drawings, and does not restrain interpretation, such as restricting interpretation of this invention by drawing code | symbol. In addition, FIG. 1 illustrates three successive stages in which a plurality of crystallization tanks, heat exchangers, and flash drums connected in series are arranged. Although FIG. 1 shows three consecutive stages as an example, the present invention is not limited to three consecutive stages.

  The purification method of the present invention uses a crude aromatic dicarboxylic acid as a raw material, and (I) a slurry adjustment step in which a crude aromatic dicarboxylic acid crystal 1 and a solvent water 2 are mixed to produce a crude aromatic dicarboxylic acid crystal slurry 3 (II) While supplying this crude aromatic dicarboxylic acid crystal slurry 3 to the slurry supply line 5, a plurality of heat exchangers H (H- (N-1), HN, H- (N + 1)) sequentially heated, heated to the melting temperature in the heat exchanger HX, and then dissolved in the crystal through the dissolution tank D. (III) Heated dissolution process (II) A hydrorefining step of bringing the crude aromatic dicarboxylic acid aqueous solution 6 into a purified dicarboxylic acid aqueous solution 7 by bringing the crude aromatic dicarboxylic acid aqueous solution 6 having a crystal component dissolved therein into contact with the catalyst in the presence of hydrogen via IV) Purified Zikaru Aqueous acid solution 7 is arranged in series and released into crystallization tank C (C- (n-1), Cn, C- (n + 1)) whose pressure has been reduced stepwise and cooled and aromatic A crystallization step of depositing dicarboxylic acid crystals to produce purified aromatic dicarboxylic acid crystal slurry 8; (V) solid liquid separation of purified aromatic dicarboxylic acid crystal slurry 8 by solid-liquid separation to recover purified aromatic dicarboxylic acid crystal 9 The liquid separation step is passed through the above steps.

  In Fig. 1, heat exchangers H (H- (N-1), HN, H- (N + 1)) arranged in three consecutive stages in the heating and melting step (II) and attached flash drum B (B -(N-1), BN, B- (N + 1)) and crystallization tanks C (C- (n-1), Cn, C- ( n + 1)) is taken out to show a heating system by the flow of water vapor, and the heating unit by the flow of water vapor of the present invention is shown as a heating unit 32 surrounded by a thin dotted line in FIG. In the heating unit 32, heat supply is constituted by the flow of introduction and discharge of water vapor, the flow of introduction and discharge of condensed water, and the flow of the following internal flow (flow 1) to (flow 6). The heat exchanger H (H- (N-1), HN, H- (N + 1)) has a flash drum B (B- (N-1), BN, B- (N + 1)). This is a container that promotes steam generation by introducing condensed water and drain separation of the introduced steam, and performs stable steam (latent heat) heating.

(Flow 1) to (Flow 6) will be described.
(Flow 1) Water vapor (line 10) generated by releasing pressure from any n-th stage C-n in the crystallization step (IV) is converted into any N-th stage heat exchanger H- in the heating and melting step (II). It introduce | transduces into the heating side of N through the heating steam introduction line 12. Water condensed after steam heating flows into the attached flash drum BN and accumulates.
(Flow 2) Heat exchanger H- (N + x) (x: installed on the downstream side (high temperature side) of the slurry supply line 5 of the crude aromatic dicarboxylic acid crystal slurry 3 from the arbitrary heat exchanger H-N. The pressure control of the flash drum B- (N + x) (x: an integer equal to or greater than 1 indicates downstream side adjacent to and beyond) The water vapor released by the (PC pressure controller) is supplied to the heated steam introduction line 12 of the heat exchanger H-N via the surplus water vapor release line 14 and used for heating.
(Flow 3) Liquid level control (LC liquid level controller) of the flash drum B- (N + x) attached to the heat exchanger H- (N + x) installed on the downstream side (high temperature side) of the slurry supply line 5 ), The water vapor caused by the release pressure of the condensed water flowing in through the transfer line 15 and the water vapor flowing in along with the condensed water in the above (flow 1) are heated from the crystallization tank C-n through the water vapor circulation line 13. It returns to the heating steam introduction line 12 leading to the exchanger H-N and is reused.
(Flow 4) To the flash drum B- (N + x) attached to the heat exchanger H- (N + x) installed on the downstream side (high temperature side) of the slurry supply line 5 of the crude aromatic dicarboxylic acid crystal slurry 3 The condensed water 11-1 collected and accumulated is introduced into the attached flash drum BN through the condensed water transfer line 15 by liquid level control (LC liquid level controller), and is released to generate steam. The generated steam is used for heating the heat exchanger HN through the steam circulation line 13 of (stream 3), and the remaining condensed water 11-1 is accumulated in the attached flash drum BN.
(Flow 5) The water vapor surplus for heating the heat exchanger HN causes the pressure increase of the attached flash drum BN, and passes through the surplus water vapor discharge line 14 by pressure control (PC pressure controller), and then the crude aromatic dicarboxylic acid. Steam for heating the heat exchanger H- (Nx) (x is an integer of 1 or more, and indicates the upstream side beyond and adjacent to the upstream side) of the acid crystal slurry 3 on the upstream side (low temperature side) of the slurry supply line 5 It is discharged and supplied to the line 12.
(Flow 6) The condensed aromatic water 11-1 accumulated in the attached flash drum BN is subjected to the crude aromatic aromatic dicarboxylic acid through the control valve 4 and the condensed water transfer line 15 by liquid level control (LC liquid level controller). Discharge to the attached flash drum B- (Nx) (x: an integer of 1 or more, indicating the upstream side beyond and adjacent) of the crystal slurry 3 on the upstream side (low temperature side) of the slurry supply line 5 Supplied. The water vapor generated by the pressure release is the above-mentioned (stream 2) and (stream 3) of the heat exchanger H- (Nx) and the attached flash drum B- (N-x) installed on the upstream side (low temperature side). Used for heating in flow.

  The heating mechanism of the heat exchanger HN and the attached flash drum BN accompanied by the flow (flow 1) to (flow 6) is controlled (PC) to a pressure substantially equal to the pressure of the crystallization tank Cn, and the attached flash drum Condensate is accumulated in the BN, and the heating unit 32 performs stable and efficient steam heating in the heat exchanger HN.

  Therefore, the present inventors have used the water vapor from the crystallization tank C-n for releasing and cooling the purified aromatic dicarboxylic acid aqueous solution 7 to perform heat exchange with the above flows (flow 1) to (flow 6). A stable and efficient heating system was invented in the heating and melting step (II) equipped with a heating unit with a vessel HN and an attached flash drum BN.

  Next, water vapor generated from the crystallization tank C- (n + 1) for releasing and cooling the purified aromatic dicarboxylic acid aqueous solution 7 is added, and the above (stream 1) to (stream 6) are replaced with the crude aromatic dicarboxylic acid. If the heating unit equipped with the heat exchanger H- (N-1) installed on the upstream side (low temperature side) of the slurry supply line 5 for the crystal slurry and the attached flash drum B- (N-1) is configured continuously, Furthermore, a stable and efficient heating system can be configured.

  Therefore, in the purification method of the crude aromatic dicarboxylic acid, water vapor generated from each crystallization tank C (C- (n + 1), Cn,..., C-1) in the crystallization step (IV) is used. In the heating and melting step (II) comprising heat exchangers connected in series, each heat exchanger is provided with a flash drum, and at least one heating unit having the above flows (flow 1) to (flow 6) is provided. By providing one, it can be set as the stable and efficient heating system.

  Therefore, in the method for purifying a crude aromatic dicarboxylic acid according to the present invention, the crystallization tank C in the crystallization step (IV) has (n + 1) groups, and the nth stage is Cn (n is an integer of 1 or more). The crystallization tank on the highest temperature and high pressure side is C-1, and the low temperature and low pressure side are C-2, C-3,..., Cn, C- (n + 1) in this order). On the other hand, if the heat exchanger H in the heating and melting step (II) is an (N + 1) group, the Nth stage heat exchanger HN (N is an integer of 1 or more, and the heat exchanger on the lowest temperature side) H-1 and sequentially H-2, H-3,..., HN, H- (N + 1) on the high temperature side) in the final stage crystallization tank C- (n + 1) The water vapor 10 generated by the release pressure can be introduced through the heating steam introduction line 12 into the heat exchanger H-1 disposed on the lowest temperature side in the heating and melting step (II).

  Next, each water vapor 10 generated by the stepwise pressure release in each crystallization tank is heated in order from the low temperature low pressure side to the high temperature high pressure side (C- (n + 1), Cn,..., C-1). Respective heat exchangers (H-1, HN,...) Arranged in the order of the flow direction (from the low temperature side to the high temperature side) of the slurry supply line 5 of the crude aromatic dicarboxylic acid crystal slurry 3 in the dissolution step (II) Introduce individually through the heating steam introduction line 12 corresponding to H− (N + 1)). The attached flash drum B, which is a condensed water receiving tank having a pressure almost equal to the shell side (heated steam side) of the Nth stage heat exchanger HN, is the Nth stage attached flash drum BN (N is an integer of 1 or more) The flash drum attached on the lowest temperature side is designated as B-1, and on the high temperature side is designated as B-2, B-3,..., BN, B- (N + 1).

(Flow 1) to (Flow 6) at this time will be described.
(Flow 1) Steam 10 generated by releasing pressure in the final stage crystallization tank C- (n + 1) on the lowest temperature and low pressure side in the crystallization step (IV) is heated and dissolved through a heated steam introduction line 12. It introduce | transduces into the heating side of the heat exchanger H-1 arrange | positioned at the coldest side of process (II). Subsequently, the steam 10 generated from the crystallization tanks Cn, C- (n-1),. Heat exchangers H-2, H-3,..., HN, H- (N arranged in the flow direction (from the low temperature side to the high temperature side) of the slurry supply line 5 of the group dicarboxylic acid crystal slurry 3 +1) is introduced individually via the heating steam introduction line 12. Each of the water vapors is heated by the respective heat exchangers H-1, H-2,..., HN, H- (N + 1), and then the condensed water 11-1 is provided with each heat exchanger. It is discharged and stored in flash drums B-1, B-2,..., BN, B- (N + 1).
(Flow 2) The slurry supply line 5 of the crude aromatic dicarboxylic acid crystal slurry 3 than the respective heat exchangers H-1, H-2, H-3, ..., HN, H- (N + 1) Rush drums B-1, B-2, ..., BN, B- (N + 1) with a heat exchanger adjacent to the downstream side (high temperature side) are discharged by pressure control (PC pressure regulator) The steam supplied to the heating steam introduction lines 12 of the heat exchangers H-0, H-1, H-2,..., HN adjacent to the upstream side (low temperature side) of each is supplied for heating. As will be described later, the heat exchanger H-0 is provided with an exhaust heat recovery device as a heat exchanger for the supply slurry preheating and the like.
(Flow 3) Liquid level control of the flash drums B-2,..., BN, B- (N + 1) with a heat exchanger adjacent to the downstream side (high temperature side) of the slurry supply line 5 (LC liquid) Generated by the release pressure of the condensed water flowing through the condensed water transfer line 15 into the respective flash drums B-1, B-2,..., BN, B- (N + 1). Steam and the water vapor entrained in the above (stream 1) pass through the water vapor circulation line 13 to the respective heat exchangers H-1, H-2, ..., HN, H- (N + 1). Reused for heating.
(Flow 4) The crude aromatic dicarboxylic acid crystal slurry 3 is more than the heat exchangers H-0, H-1, H-2, H-3,..., HN, H- (N + 1). Flush drum B attached to each heat exchanger H-1, H-2, H-3, ..., HN, H- (N + 1) adjacent to the downstream side (high temperature side) of the slurry supply line 5 -1, B-2, B-3, ..., BN, B- (N + 1) collected and accumulated condensed water 11-1 is respectively controlled by liquid level control (LC liquid level controller) Are introduced into the attached flash drums B-0, B-1, B-2,..., BN adjacent to the upstream side (low temperature side) through the condensate transfer line 15 and released to generate water vapor. Each generated water vapor is used for heating the respective heat exchangers H-0, H-1, H-2,..., HN through the water vapor circulation line 13, and the remaining condensed water is used for each attached flash drum. B-0, B-1, B-2, ..., stored in BN. As will be described later, the flash drum B-0 is installed as a flash drum attached to the heat exchanger H-0 or as a condensed water recovery tank.
(Flow 5) The water vapor surplus for heating the heat exchangers H-1, H-2,..., HN, H- (N + 1) is supplied to the respective flash drums B-1, B. -2, ..., Heat exchangers H-0, H- adjacent to the upstream side (low temperature side) of the slurry supply line 5 by pressure control (PC pressure controller) of BN, B- (N + 1) 1, H-2,..., HN are discharged to respective heating steam introduction lines 12.
(Flow 6) The condensed water 11-1 accumulated in each of the attached flash drums B-1, B-2,..., BN, B- (N + 1) is liquid level control (LC liquid level controller). ) Is supplied to each of the attached flash drums B-0, B-1, B-2,... BN adjacent to the upstream side (low temperature side) of the slurry supply line 5.

  By the water vapor generated from each crystallization tank C- (n + 1), Cn,..., C-2, C-1 in the crystallization step (IV), the above (stream 1) to (stream 6) Heat exchangers H-1, H-2,..., HN, H- (N + 1) and attached flash drums B-1, B-2,. -Each heating unit according to (N + 1) sequentially heats the crude aromatic dicarboxylic acid crystal slurry 3 from the upstream side (low temperature and low pressure side) of the slurry supply line 5 and performs heat exchange on the most downstream side (high temperature side). Heating using the heating and melting step (II) in which the apparatus H- (N + 1) and the attached flash drum B- (N + 1) are composed of the deformation heating unit 33 in which (stream 2) and (stream 4) do not exist A system can be constructed.

  In the system configuration of this steam heating flow, the condensed water and steam discharged from the attached flash drum B-1 installed on the most upstream side (low temperature side) of the slurry supply line 5 of the crude aromatic dicarboxylic acid crystal slurry 3 are at the lowest temperature. Condensed water 11-1 and steam at low pressure are used, and the temperature (heat) of the condensed water and steam is further installed, a preheating heat exchanger H-0 for the slurry supply line 5 and an attached flash drum B-0 are installed. Heat recovery. The flash drum B-0 is installed as a collection tank for the total amount of condensed water in the heating and dissolving step (II) of the present invention.

  In this heating system, in the heating unit of the heat exchanger H- (N + 1) on the most downstream side (high temperature side) of the flow of the slurry feed line 5 of the crude aromatic dicarboxylic acid crystal slurry 3, the heat exchanger H -There is no additional flash drum installed downstream (high temperature side) from (N + 1), and there is no introduction of condensed water or surplus steam, that is, (flow 2) and (flow) described above 4) is constituted by a deformed heating unit (the one-dot chain line range in FIG. 1, the deformed heating unit 33) in which there is no flow.

  As described above, in the heating system in which the latent heat of water vapor generated in the crystallization step (IV) is more stably and efficiently recovered and reused in the heating and dissolving step (II) in which the heat is continuously and sequentially heated, It is necessary to have a system configuration including at least a deformation heating unit for connecting the heating units.

  Further, in the heating and dissolving step (II), water vapor generated from the respective crystallization tanks C-1, C-2,..., Cn, C- (n + 1) in the crystallization step (IV) is sequentially added. Heat exchangers H- (N + 1), HN, ..., H-2, H-1 are supplied for heating, and the heating unit 32 is sequentially connected from the most downstream side (high temperature side) of the slurry supply line 5. Unlike the above-described typical heating system, steam (stream 2) and / or condensed water (stream 4) discharged from the flash drum B attached to the heating unit connected to the downstream side (high temperature side) of the slurry supply line 5 However, in the case of a heating system in which every other, every other, or a mixture of them, is configured, a deformation heating without introducing steam and / or condensed water into the downstream (high temperature side) heating unit 32 The unit 33 is configured to be incorporated with 2 units and 3 units. (One deformation heating unit 33 exists in the most downstream (high temperature side) heat exchanger H and the attached flash drum B.)

  For example, as a method for purifying crude terephthalic acid, the system configuration of a heating unit as shown in the flow chart of FIG. 3 includes two deformation heating units (H-4 (B-4) and H-5 (B-5)). It becomes the heating dissolution process (II).

  Therefore, in order to obtain a more stable method for purifying crude aromatic dicarboxylic acid, a heating unit 32 on the downstream side (high temperature side) of the slurry supply line 5 is added to the heating and dissolving step (II) of the crude aromatic dicarboxylic acid crystal slurry. It would be preferable to construct a system with at least one modified heating unit 33 without the introduction of water vapor (stream 2) and / or condensed water (stream 4) from the flash drum.

  Therefore, a heating unit 32 comprising a heat exchanger and an attached flash drum, in which a plurality of crude aromatic dicarboxylic acid crystal slurries are connected in series using water vapor generated from crystallization tanks having different pressures in the crystallization step (IV). In the heating and dissolving step (II) according to the above, the apparatus for purifying aromatic dicarboxylic acid provided with at least one deformation heating unit 33 is the most stable and most efficient purification apparatus capable of recovering heat.

  Further, all the water vapor generated from the crystallization tank in the crystallization step (IV) is supplied from the attached flash drum B-1 installed at the most upstream side (low temperature side) of the slurry supply line 5 and the final crystallization tank C- ( It is collected and recovered as condensed water (about 100 to 170 ° C.) having a vapor pressure almost equal to the pressure of n + 1) (about 0.1 to 0.9 MPa). The condensed water is used as it is or after it is heat-recovered and used as a part of the water for dissolving the crude aromatic dicarboxylic acid crystal as it is or after being treated.

  However, the coldest condensed water 11-1 discharged and recovered from the flash drum B-1 attached to the most upstream side (low temperature side) of the slurry supply line 5 is evaporated when the crystallization tank is cooled under pressure. A small amount of methylbenzoic acid, which is an impurity of purified aromatic dicarboxylic acid, is contained. Therefore, the method for treating the condensed water discharged and recovered from the heating and dissolving step (II) is examined, and the presence of aromatic dicarboxylic acid crystals in the recovered condensed water 11-2 reduces the methylbenzoic acid content in the condensed water. I found out. Based on this knowledge, a process was constructed that uses a larger amount of the recovered condensed water 11-2 as a part of water for dissolving the crude aromatic dicarboxylic acid crystal (FIG. 1).

  In this method, the aromatic dicarboxylic acid crystal 16 is added to the condensed water 11-2 that has flowed out and recovered from the attached flash drum B-1, and the separated crystal 18 and the separated water 17 are obtained by solid-liquid separation. The separated water 17 subjected to solid-liquid separation is sent to the slurry adjusting step (I) and used as a part of the aqueous solvent 2 for preparing the crude aromatic dicarboxylic acid crystal slurry 3. The aromatic dicarboxylic acid separated crystal 18 recovered by solid-liquid separation is recycled to the oxidation reaction as part of the raw material of the crude aromatic dicarboxylic acid crystal production process 19.

  Accordingly, the present invention provides a heating system comprising a heating system comprising a combination of the heating unit 32 and the deformation heating unit 33 with the total water vapor generated from each crystallization tank in the crystallization step (IV) in the purification method of the crude aromatic dicarboxylic acid. Introduced into the dissolution process (II), until the condensed water has a vapor pressure close to atmospheric pressure (approximately 0.1 MPa), the enthalpy of total latent heat of vapor is a stable and efficient heat recovery system, and crude aromatic dicarboxylic acid crystals This makes it possible to reduce the heating energy of the slurry.

  Then, the condensed water that released almost all of the latent heat of the water vapor generated from each crystallization tank in the crystallization step (IV) was recovered, and a method for purifying the condensed water (reducing the impurity content) was found. Water can be used as part of the water to dissolve the crude aromatic dicarboxylic acid crystals, and new dissolved water can be reduced in the aromatic dicarboxylic acid crystal dissolution process.

  The present invention is not limited to the above-described method for purifying a crude aromatic dicarboxylic acid, but a crystalline organic synthetic compound as a raw material is dissolved in a solvent under high temperature and high pressure to obtain a solution, and purification such as adsorption purification is performed as it is. The present invention can also be applied to a method of recrystallizing an organic compound only by dissolving it.

  As an example, the present invention can be applied to a recrystallization purification method or the like in which crude dimethyl terephthalate as a polyester raw material is purified with methanol. That is, after mixing a crystalline organic synthetic compound and a solvent to form a mixed slurry, a plurality of the mixed slurries are connected in series using solvent vapor generated under gradual pressure reduction from a plurality of crystallization tanks in the crystallization process. In the refining method for heating in the heating and melting step comprising the heat exchanger of the above and the attached flash drum, a purification method using a purifying apparatus to which the heating and melting step in which the heating unit and the deformation heating unit according to the present invention are configured is applied. Can do.

  In the purification method involving heating and cooling of the crude aromatic dicarboxylic acid, the introduction of the steam heating system comprising the heating unit of the present invention can recover most of the latent heat enthalpy of water vapor generated from the crystallization tank, and the stability of heat exchange And by improving efficiency, downsizing of the equipment (heat exchanger) can be achieved.

  Furthermore, by providing a heating and melting step in which a heating unit and a deformation heating system are combined to form a system, a large amount of heating heat energy up to the purification temperature up to a crude aromatic dicarboxylic acid crystal aqueous solution is obtained. Reduced consumption.

  Further, the condensed water from which most of the latent heat energy of the heating steam is released can be recycled as the purification solvent water by performing the purification treatment according to the present invention. A method capable of reducing the above is provided. Furthermore, the amount of water discharged outside the manufacturing process system is reduced by circulating and effectively using the solvent water for purification within the manufacturing process, and the processing load when the waste water is treated as industrial waste water is also reduced. Connected.

Schematic flow diagram of purification process of crude aromatic dicarboxylic acid and heating method of heating unit and deformation heating unit of the present invention by system configuration in which vapor generated from crystallization tank is introduced into heat exchanger and integrated with attached flash drum It is the flowchart which showed an example. FIG. 2 is a process diagram showing a typical system configuration (the most downstream side (high temperature side) is a deformation heating unit) in which the heating unit of the present invention is applied along the heating flow of a crude terephthalic acid crystal slurry; FIG. In the system configuration of the heating unit of the present invention, it is an example of a purification process of crude terephthalic acid that is a heating system that supplies surplus steam and condensed water discharged from the heating unit to every other upstream (low temperature side) heating unit. FIG. 10 is a flowchart of Example 2. In a crude terephthalic acid refining method, it is an example of the process which showed the heating system of the conventional method of carrying out the steam heating of the raw material supply slurry, and is the flowchart of the example of patent document 2, and a comparative example. In the system configuration of FIG. 2 of the heating unit of the present invention, it is an example of a purification process of crude terephthalic acid to which a heating system having a deformation heating unit on the most upstream side (low temperature side) of the raw material supply slurry is applied. FIG. It is a table | surface which shows the simulation result of the temperature rise of the crude terephthalic-acid crystal slurry supply line from the heat exchangers H-0 to H-5 of Example 1, Example 2, and a comparative example. It is a table | surface which shows the simulation result of the ultrahigh pressure steam reduction amount on the basis of the ultrahigh pressure steam quantity of Example 1 and Example 2 required for heating a crude terephthalic acid crystal slurry to 285 degreeC, and a comparative example. It is a table | surface which shows the crystallization tank pressure of the water vapor | steam corresponding to each heat exchanger in Example 3, the heat-transfer area of each heat exchanger, and outlet temperature. In the Example which added refined terephthalic acid crystal | crystallization to the recovered condensed water of Example 4, it is a table | surface which shows the addition amount and the content of p-toluic acid in separated water.

  First, a conventional method for producing purified terephthalic acid from crude terephthalic acid, which is the premise of the present invention, will be described with reference to the flow of FIG.

The process for producing purified terephthalic acid using crude terephthalic acid as a raw material is as follows.
Slurry preparation step (I): The crude terephthalic acid crystal 23 and the water 2 are mixed to produce a crude terephthalic acid crystal slurry of about 20 to 40% by weight.
Heat-dissolving step (II): Heat exchanger (six H-0 to H units) in which a plurality of crude terephthalic acid crystal slurries are connected in series (total 7 units H-0 to H-6) under pressure (about 6 to 10 MPa) -5), sequentially heated, and heated in the final heat exchange (H-6) to a temperature of about 260-300 ° C with ultra high pressure steam (about 300 ° C or more, about 9.0MPa or more). Furthermore, it is kept for about 1 to 20 minutes under high temperature and high pressure, and the crystal component is dissolved in a dissolution tank (FIG. 4, not shown) to obtain a crude terephthalic acid aqueous solution.
Hydrorefining step (III): A high-temperature and high-pressure crude terephthalic acid crystal aqueous solution is brought into contact with a catalyst in the presence of high-pressure hydrogen gas 25 to obtain a purified terephthalic acid aqueous solution 27. As the catalyst, generally used is an activated carbon catalyst carrying 0.1 to 1% by weight of Pd.
Crystallization step (IV): Using a crystallization tank (C-1 to C-5) in which the purified terephthalic acid aqueous solution 27 is arranged in series and the pressure of a plurality (5 stages, 5 stages) is lowered stepwise. Then, the pressure is released, evaporated and cooled until the pressure in the final stage crystallization tank becomes 0.2 to 0.8 MPa (120 to 170 ° C.), and the terephthalic acid crystals are sequentially precipitated to produce the purified terephthalic acid crystal slurry 28. The steam generated by the stepwise pressure release from each crystallization tank is individually introduced into each heat exchanger as a heating medium in the heating and melting step (II).
Solid-liquid separation step (V): The purified terephthalic acid crystal slurry 28 is introduced into the solid-liquid separation device S while maintaining the pressure of the final crystallization tank C-5, and after solid-liquid separation, the crystals are washed. The purified terephthalic acid crystal 30 is recovered.

  In the purified terephthalic acid production steps (I) to (V), the present invention relates to a heating system that utilizes water vapor generated in the crystallization step (IV) in the heating and dissolving step (II) of the crude terephthalic acid crystal slurry. .

  In addition, five-stage crystallization tanks C-1, C-2, C-3, C- in which the pressure of purified terephthalic acid aqueous solution under high temperature and high pressure (about 260-300 ° C, about 4.8-9MPa) was reduced stepwise The water vapor 10 generated from each crystallization tank in the crystallization process (IV) consisting of 4 and C-5 depends on the pressure and temperature determined by optimizing the properties of the crystallized crystal, etc. The present invention is a method of heating using generated steam.

  For example, in JP-A-8-208561, the first crystallization tank is 240 to 260 ° C. (about 3.4 to 4.8 MPa), the second crystallization tank is 180 to 230 ° C. (about 1 to 2.9 MPa), and the fifth crystallization is performed. It is said that the tank is heated with steam generated from 150 ℃ (about 0.5MPa).

  Next, in the method for purifying crude terephthalic acid, an embodiment of a heating system provided with the heating unit and the deformation heating unit of the present invention will be described with reference to the flow of FIG.

  In the heating and melting step (II), water vapor 10 generated from each crystallization tank (C-1, C-2, C-3, C-4, C-5) in the crystallization step (IV) Side) heat exchanger H-5 in order from the low pressure side (low temperature side) heat exchanger H-1. The final heat exchanger H-6 has an ultra-high pressure exceeding 300 ° C (approximately 9 MPa) until the crude terephthalic acid crystal slurry at the outlet of the heat exchanger H-5 becomes an aqueous solution (temperature of hydrogenation reaction 260-300 ° C). Controlled heating (TC temperature controller) is performed using water vapor 26 or a heating medium. In the case of the ultrahigh-pressure steam 26 introduced into the final heat exchanger H-6, it is recovered in the attached flash drum B-6 as condensed water holding a pressure of about 9 MPa or more.

  The excess steam recovered in the flash drum B-6 with the heat exchanger is sufficiently recovered from the latent heat of the steam by the steam discharge circulation line 13 to the ultrahigh-pressure steam introduction line to become condensed water. Since the condensed water discharged from the heat exchanger H-6 retains high pressure (about 9MPa or more), it accumulates in the attached flash drum B-6, and then is discharged out of the system as high-pressure wastewater 24. It can be used for applications that effectively utilize the high temperature and high pressure.

  The steam entrained in the flash drum B-6 provided with the heat exchanger is sent from the steam circulation line 13 to the introduction line of the ultrahigh-pressure steam 26, and is condensed in the attached flash drum B-6 as a condensed water that sufficiently recovers the latent heat of the steam. To be recovered. Although not shown in the figure, the recovered high-temperature condensate is transferred to the attached flash drum B-5, released, and steam is generated and introduced into the heating system as heating steam of the heat exchanger H-5. You can also.

  On the other hand, when using a heating medium such as Dowsum (Dowtherm), the heating medium is heated in a combustion furnace, supplied in liquid form to the heat exchanger H-6, and the heated heating medium is circulated. It becomes a reuse system, and it becomes a simple process about the heat medium after heating, and the process of residual heat.

  The purified terephthalic acid aqueous solution 27 purified by the hydrorefining apparatus R in the hydrorefining step (III) is sent to the first crystallization tank C-1 held at about 3.5 to 6 MPa in the crystallization step (IV). Then, the pressure is released and cooled (about 240 to 270 ° C.), and the crystallization tanks C-2, C-3, C-4, and C-5 are sequentially released, cooled, and precipitated, and the purified terephthalic acid crystal slurry 28 is formed. Generate. The water vapor 10 generated by the pressure release is introduced into the heat exchanger H-5 sequentially from the heat exchanger H-5 to the H-4, H-3, H-2, and H-1 through the heated steam introduction line 12, and used to heat the crude terephthalic acid crystal slurry. Is done.

  The steam in the heating steam introduction line 12 supplied for heating the heat exchanger H-5 in the heating and melting step (II) is used for heating the heat exchanger H-5 together with the steam from the steam circulation line 13, and condensed water. 11-1 is collected and stored in the attached flash drum B-5. The water vapor that could not be condensed (latent heat recovery) in the heat exchanger H-5, that is, the surplus water vapor becomes the rising pressure of the attached flash drum B-5, so that the pressure control valve 4 (PC pressure controller) Heated steam introduction line 12 of the heat exchanger H-4 on the upstream side (low temperature and low pressure side) of the crude terephthalic acid crystal slurry supply line 12 (connected to the second crystallization tank C-2) through the water vapor discharge line 14 To the crude terephthalic acid crystal slurry. Further, the condensed water 11-1 accumulated in the attached flash drum B-5 is discharged to the attached flash drum B-4 on the upstream side (low temperature and low pressure side) by the liquid level control valve 4 (LC liquid level controller). The heating unit for the steam flow by the steam latent heat exchange of the heat exchanger H-5 is a deformation heating unit (see the deformation heating unit 33 in FIG. 1, there is no introduction of condensed water and excess steam from the downstream side).

  On the other hand, the purified terephthalic acid crystal slurry produced in the first crystallization tank C-1 of the crystallization step (IV) is transferred to the second crystallization tank C-2 maintained at about 1.5 to 4 MPa and released. To be cooled. Here, the terephthalic acid crystal concentration of the purified terephthalic acid crystal slurry further increases (crystal precipitation). The water vapor generated by the pressure release is introduced into the heat exchanger H-4 through the heated steam introduction line 12 of the second crystallization tank C-2.

  The water vapor 10 introduced into the heat exchanger H-4 in the heating and dissolving step (II) heats the heat exchanger H-4, and is collected and accumulated in the attached flash drum B-4 as condensed water 11-1. The water vapor accompanying the condensed water is supplied to the heat exchanger H-4 through the auxiliary flash drum B-4 through the water vapor circulation line 13. At the same time, the condensed water transferred by the liquid level control (LC controller) from the attached flash drum B-5 is transferred to the attached flash drum B-4, where it is depressurized. The condensed steam recovered as the condensed water 11-1 having a temperature of 190 to 250 ° C. is supplied from the steam circulation line 13 to the heat exchanger H-4.

  The pressure of the steam introduced into the attached flash drum B-4 and the steam that increases the pressure inside the attached flash drum B-4 due to the introduction and release of condensed water from the attached flash drum B-5 are controlled by pressure control. Heated steam introduction line 12 (third crystal) of heat exchanger H-3 on the upstream side (low temperature and low pressure side) of slurry supply line 5 of the crude terephthalic acid crystal slurry through valve (PC pressure controller) through steam release line 14 From the deposition tank C-3 to the heating steam introduction line) and supplied to the heat exchanger H-3. In addition, let the structure of the water vapor | steam flow of the water vapor | steam latent heat exchange of the said heat exchanger H-4 be a heating unit (refer FIG. 1 heating unit 32).

  Subsequently, heat exchanger H-3, heat exchanger H-2, and heat exchanger H-1 are respectively connected to third crystallization tank C-3 (about 1 to 2.5 MPa) and second crystallization tank C-4 ( About 0.6 to 1.2 MPa), the steam generated from the first crystallization tank C-5 (about 0.1 to 0.8 MPa) is used to sequentially heat the steam heating system of FIG. Condensed water is sequentially transferred to a flash drum, released and recovered. In the attached flash drum B-1 (about 0.1 to 8 MPa), all the water vapor supplied for heating is collected and condensed as condensed water of about 100 to 170 ° C.

  In FIG. 2, the preheat heat exchanger H-0 is generated by the surplus steam from the attached flash drum B-1 and the generated steam (crystal crystallization) due to the release of the condensed water transferred by the liquid level control LC (transport pump P-3). A heating unit with a flow that can utilize the final latent heat as a preheating part (crude terephthalic acid crystal slurry temperature of about 90 ° C) of the slurry supply line of the crude terephthalic acid crystal slurry was added. It is a flow. The condensed water (about 100 to 170 ° C.) can also be used as a heating medium for equipment and processes other than the heat exchanger H-0.

  As described above, in the process of producing purified terephthalic acid, as shown in FIG. 2, the method of the present invention uses water vapor of different pressures generated step by step from each crystallization tank in the crystallization step (IV), Steam heating consisting of 7 heat exchangers for heating the crude terephthalic acid crystal slurry and 6 heating units consisting of an attached flash drum (excluding the final heat exchanger H-6 as a heating unit) and 1 deformation heating unit Although the embodiment in which the generated steam is recovered as low-temperature (about 100 ° C. or lower) condensed water by the heating and melting step (II) of the method has been described, the number of heat exchangers, the number of crystallization tanks, and the number of heating units are It is not limited to FIG.

  Therefore, in the method for purifying crude terephthalic acid in FIG. 2, as a modified example, the heating unit in the heating and dissolving step (II) of the crude terephthalic acid crystal slurry and the system configuration of the deformation heating unit are as shown in the flowchart of FIG. It can be implemented as a system configuration comprising four heating units and two deformation heating units.

  The number of heat exchangers installed is a heating unit corresponding to at least one heat exchanger and an attached flash drum for each of the water vapor 10 generated from the purified terephthalic acid aqueous solution 27 according to the pressure stage of the crystallization tank. Is necessary. Further, it is possible to use a heating unit corresponding to one flash drum using two heat exchangers corresponding to the generated steam to be introduced, and in addition to this, at least an attached flash drum corresponding to the heat exchanger It is necessary to form a heating unit with a combination of one unit.

  The design of the heat exchanger as the main axis when applying the heating unit 32 (including the deformation heating unit 33) shown in FIG. 1 of the present invention to the purification method of terephthalic acid is the amount of the crude terephthalic acid crystal slurry supplied first. Start by setting. That is, it starts from introduction of a high-temperature purified aqueous terephthalic acid solution corresponding to the amount of crude terephthalic acid crystal slurry to be supplied to the crystallization step (IV). In each crystallization tank in the crystallization step (IV), the temperature and the amount of steam generated by releasing the pressure by reducing the pressure stepwise are determined by the set pressure of each crystallization tank.

  The set pressures of the crystallization tanks used in the production of purified terephthalic acid are within the above-mentioned crystallization tank pressure ranges (first crystallization tank C-1 = about 3.5 to 6 MPa, second crystallization tank. C-2 = about 1.5 to 4 MPa, third crystallization tank C-3 = about 1 to 2.5 MPa, second crystallization tank C-4 = about 0.6 to 1.2 MPa, first crystallization tank C-5 = about 0.1 ~ 0.8MPa).

  The high-temperature (260-300 ° C) purified terephthalic acid aqueous solution introduced in the crystallization step (IV) is released at the pressure of each crystallization tank, and the temperature and amount of steam released from each crystallization tank. Is calculated. The generated steam is supplied to each heating unit 32 (including the deformation heating unit 33).

  In each heating unit 32 (including the deformation heating unit 33), the heat exchanger is designed by balancing the amount of water vapor supplied from the crystallization tank and the heating temperature of the supplied crude terephthalic acid crystal slurry. However, in actuality, the amount of steam for heating in the heat exchanger is such that surplus steam from the heating unit on the downstream side (high temperature side) of the slurry supply line 5 of the crude terephthalic acid crystal slurry and generated steam from the transferred condensed water are added to the supplied steam. Will join. Then, the introduction steam and the heat balance are sequentially repeated in the direction of the heating unit on the upstream side (low temperature side) of the slurry supply line 5 of the crude terephthalic acid crystal slurry, and the temperature rise of the supplied crude terephthalic acid crystal slurry in each heat exchanger Will be calculated. Based on these, the conditions of each heat exchanger are set, and the number of installed heat exchangers is set. The amount of steam generated from each crystallization tank in the crystallization step (IV) is calculated from the above set pressure. The total amount of steam generated at each stage temperature of crystallization of the purified terephthalic acid aqueous solution is adjusted by slurry adjustment. The amount corresponds to about 20 to 40% by weight of the total solvent water of the crude terephthalic acid crystal slurry prepared in the tank A.

Next, the heat transfer area, size, and the like of each heat exchanger are calculated from the supply amount of the crude terephthalic acid crystal slurry in each heat exchanger and its rising temperature, and each heat exchanger is designed. As the terephthalic acid production apparatus increases in size, the heat exchanger is usually a multi-tubular heat exchanger in which the crude terephthalic acid crystal slurry passes through the tube side and heating steam is supplied to the shell side. At that time, the heat transfer coefficient in the steam condensation heating type multi-tube heat exchanger which is the method of the present invention was calculated as about 1,000 kcal / m ² hr ° C.

  The flash drum attached to the heat exchanger needs to be a pressure resistant vessel provided with a control valve with a liquid level controller for collecting and storing condensed water. And the condensed water inflow port of the generated steam from the crystallization tank and the condensed water discharge port from the heating unit on the downstream side (high temperature side) of the slurry supply line 5 of the crude terephthalic acid crystal slurry are accumulated in the flash drum. It is preferable to install in the condensed water (under the liquid level), and it is preferable that the surplus steam and the discharge steam pass under the condensed water surface and be discharged.

  In this way, the condensed water collected in the flash drum under almost normal pressure (about 100 ° C. or less) contains a little p-toluic acid, which is an impurity of purified terephthalic acid. Therefore, purified terephthalic acid crystals are added to the recovered condensed water at a ratio of about 0.01 wt% or more, and the crystals are separated by a method such as sedimentation or filtration to recover the separated crystals 18 and the separated water 17. The purified terephthalic acid crystal 29 added here may be one in the process system.

  As a result, the content of p-toluic acid, which is an impurity of the purified terephthalic acid in the separated water 17, is about half or less compared to the state in which no crystals are added, and it is used as part of the solvent water for preparing the crude terephthalic acid crystal slurry. The amount that can be expanded. This can further increase the amount of about 25% by weight (Patent Document 4, Example 1, direct use of separated water), which is the amount of conventional separated water used. In the method according to the present invention, almost all of the condensed water of the steam generated from the crystallization step (IV) can be used as a part of the solvent water.

  In addition, since the main component to which p-toluic acid is attached is a terephthalic acid crystal, the separated and recovered crystal can be used as a raw material for a crude terephthalic acid production process. Therefore, it can be recovered as terephthalic acid including the reaction intermediate p-toluic acid without losing the added terephthalic acid crystals.

  As mentioned above, although embodiment of this invention method was illustrated as a refinement | purification method of crude terephthalic acid, there exist terephthalic acid and isophthalic acid as a typical thing with aromatic dicarboxylic acid. Although terephthalic acid and isophthalic acid are both poorly soluble in water, the solubility of isophthalic acid is about 10 times greater than that of terephthalic acid. Therefore, the temperature and pressure of the aqueous solution for hydrorefining are about 260 to 300 ° C. and about 5 to 9 MPa for terephthalic acid, and about 180 to 230 ° C. and about 1 to 3 MPa for isophthalic acid. And in the crystallization process, each refined dicarboxylic acid is manufactured by releasing pressure from those temperatures stepwise. Therefore, the heating and dissolving step (II) provided with the heating system by the heating unit and the deformation heating unit, which is the method of the present invention, can also be carried out in a method for purifying crude isophthalic acid.

  In addition to the method for purifying aromatic dicarboxylic acids as described above, the method of the present invention is applied to methods for solvent purification of crystalline organic compounds (physical and chemical purification by solution, recrystallization purification by solvent, etc.). Can do.

  Next, the method of the present invention will be described with reference to examples. However, the method of the present invention is not limited to the following examples.

  In the slurry preparation step (I), heating and dissolving step (II), hydrorefining step (III), crystallization step (IV), and solid-liquid separation step (V) for producing purified terephthalic acid using crude terephthalic acid as a raw material, According to the flow shown in FIG. 2, the water vapor generated by the pressure-reduction cooling in the crystallization step (IV) is supplied to the heat exchanger that heats the crude terephthalic acid crystal slurry through the slurry supply line 5 in the heating / dissolution step (II). The temperature rise of the heat exchanger was set, and the reduction of super high pressure steam was examined.

  A crude terephthalic acid crystal slurry, which is a raw material to be heated, is supplied at a rate of 100 parts by weight / hour to the slurry supply line 5 in the heating and dissolving step (II), and five purified terephthalic acid aqueous solutions in the crystallization step (IV) After using the steam generated by the gradual pressure release from each stage of the crystallization tank, the heating unit 32 (see FIG. 1) using the heat exchanger of the heating and melting step (II) and the attached flash drum (see FIG. 1), A crude terephthalic acid aqueous solution was obtained by heating to 285 ° C. using ultra-high pressure steam (about 300 ° C.). At this time, the temperature and the amount (vapor amount) of steam generated from the crystallization tank of 5 groups and 5 stages in the crystallization step (IV) were assumed as shown in FIG.

The flow of the sequential heating step by the heating unit 32 in the heating and dissolving step (II) will be described with reference to FIG.
Step 1: The preheating heat exchanger H-0 includes the steam supplied from the surplus steam control line 14 of the adjacent attached flash drum B-1, and the condensed water 11-1 accumulated in the attached flash drum B-1. Was transferred to an attached flash drum B-0, and steam generated by releasing pressure (normal pressure, 100 ° C.) was circulated from the steam circulation line 13 and heated. The heating of the slurry supply line 5 of the crude terephthalic acid crystal slurry was set at 90 ° C. as the upper limit in the preheating heat exchanger H-0.
Step 2: In the heat exchanger H-1, water vapor (143 ° C., 2.4 parts by weight) generated in the crystallization tank C-5, water vapor sent from the surplus water vapor discharge line 14 of the attached flash drum B-2, and the auxiliary equipment The condensed water 11 accumulated in the flash drum B-2 is transferred to the attached flash drum B-1, and the water vapor generated by the release pressure (about 3 kg / cm 2 G) is circulated from the water vapor circulation line 13 and heated (FIG. 1). Equivalent to the heating unit). The upper limit of the heating in the heat exchanger H-1 was 133 ° C., and the surplus steam was supplied to the heat exchanger H-0 through the surplus steam discharge line 14.
Step 3: In the heat exchanger H-2, the generated steam (166 ° C, 4.0 parts by weight) in the crystallization tank C-4 is surplus in the attached flash drum B-3 adjacent to the high-temperature and high-pressure side in the same manner as in Step 2 above. It heated with the water vapor | steam sent from the water vapor | steam discharge line 14, and the water vapor | steam accompanying the pressure release of the accumulation condensed water 11-1 (equivalent to the heating unit of FIG. 1). Note that the heating in the heat exchanger H-2 had an upper limit of 156 ° C., and the surplus steam was supplied to the heat exchanger H-1 through the surplus steam discharge line 14.
Step 4: As above, in the heat exchangers H-3 and H-4, water vapor generated from the crystallization tanks C-3 and C-2 (H-3 (198 ° C., 6.3 parts by weight), H-4 ( 233 ° C., 9.6 parts by weight)), steam sent from the surplus steam discharge line 14 from the attached flash drums B-4 and B-5 on the high temperature and high pressure side, respectively, and steam accompanying the release pressure of the accumulated condensed water 11-1 (Corresponding to the heating unit 32 in FIG. 1). Heating in the heat exchanger H-3 has an upper limit of 188 ° C, heating in the heat exchanger H-4 has an upper limit of 223 ° C, and each excess steam is heated in the heat exchangers H-2 and H-3. It was used for.
Step 5: In the heat exchanger H-5, heating was performed only with the generated steam (264 ° C., 9.1 parts by weight) from the crystallization tank C-1 (corresponding to the deformation heating unit 33 in FIG. 1).
Step 6: In the heat exchanger H-6, the ultra high pressure steam (about 85 kg / cm2G) is used, and the slurry supply line 5 of the crude terephthalic acid crystal slurry heated by the heat exchangers H-1 to H-5 is 285 ° C. Heated until.

  Based on the above design values, the temperature of the crude terephthalic acid crystal slurry is increased by heat exchanger H-0, heat exchangers H-1 to H-5, and the amount of heat of the heating steam is changed from heat exchangers H-5 to H. -1 and then to the residual heat exchanger H-0 were transferred from the downstream side (high temperature side) as surplus steam and condensed water.

  As a result, FIG. 6 and Example 1 describe the temperature rise of the crude terephthalic acid crystal slurry. In addition, FIG. 6 also described the heating steam temperature and the amount of steam heated (vs. 100 parts by weight of supply slurry / hour), and each heat exchanger set upper limit temperature.

  As a result, the preheating heat exchanger H-0 and the heat exchangers H-1 to H-4 were sufficiently heated to the upper limit set temperature, but the rising temperature of the heat exchanger H-5 was 246. It was up to ° C. This is because the heat exchanger H-5 is heated only by the steam heating generated in the crystallization tank C-1. Further, the amount of steam in the heat exchanger H-6 required to heat the crude terephthalic acid crystal slurry of the heat exchanger H-5 to a final temperature of 285 ° C. was 20.4 parts by weight / hour (FIG. 7). This steam amount was reduced by 42% compared with the conventional method (comparative example).

  The crude terephthalic acid crystal slurry is heated using water vapor from the crystallization tank generated by releasing and cooling the purified terephthalic acid aqueous solution in the same manner as in Example 1, and is sent from the surplus water vapor control line 14 of the attached flash drum. And the accumulated condensed water 11-1 was heated by the system which introduce | transduced the heating unit which circulates and conveys to every other low temperature low pressure side shown in FIG. At that time, the heat exchangers H-5 and H-4 become deformation heating units. In addition, the surplus steam and accumulated condensate of two different pressures of the flash drums B-2 and B-1 with the heat exchanger are transferred to the heat exchanger H-0 and the flash drum B-0, and the flash drum is attached. Total condensed water was recovered in B-0. Further, the heating upper limit temperature in each of the heat exchangers H-0, H-1, H-2, H-3, H-4, and H-5 was set to be the same as the set temperature in Example 1.

FIG. 6 shows the simulation results of the rising temperature of the crude terephthalic acid crystal slurry supply line 5 from the heat exchangers H-0 to H-5 according to Example 2 as in Example 1.
In addition, the amount of steam in the heat exchanger H-6 required to heat the crude terephthalic acid crystal slurry of the heat exchanger H-5 to a final temperature of 285 ° C. was 21.0 parts by weight / hour (FIG. 7). This amount of steam was reduced by 40% based on the result of the conventional method (comparative example).

<Comparative example>
The crude terephthalic acid crystal slurry was heated using water vapor from the crystallization tank generated by releasing and cooling the purified terephthalic acid aqueous solution in the same manner as in Example 1, and heat exchangers H-1 to H were used as shown in FIG. The system that collects and heats all the condensed water in the heat exchanger H-0 without using a flash drum attached to -5 was studied. This is a system in which the excess heat energy in each heat exchanger is integrated and heated in the heat exchanger H-0.

  FIG. 6 shows the rising temperature of the slurry supply line of the crude terephthalic acid crystal slurry from the heat exchangers H-0 to H-5 according to the above set values, as in Example 1. The amount of steam in the heat exchanger H-6 required to heat the crude terephthalic acid crystal slurry of the heat exchanger H-5 to a final temperature of 285 ° C. was 35.2 parts by weight / hour (FIG. 7).

  Purified terephthalic acid was produced from crude terephthalic acid using the flow of FIG. In this flow, approximately 27% by weight of crude terephthalic acid crystal slurry is supplied through the slurry supply line 5 at a rate of 100 parts by weight / hour, and each crystallization tank (C-1, C-2, C-3, C-4, C-5) Each heat exchanger (H-1, H-2, H-3, H-4) of the generated steam by the pressure setting (Fig. 8) (II) , H-5) and the supplied crude terephthalic acid crystal slurry was heated. The heating system comprises three units (H-2, H-3, H-4) of heating units according to the present invention and two units (H-1, H-5) of deformation heating units.

The supplied crude terephthalic acid crystal slurry heated to the heat exchanger H-5 outlet temperature is heated to 285 ° C. in the heat exchanger H-6 to obtain a crude terephthalic acid aqueous solution, and then purified by a hydrorefining apparatus. The heat exchanger in this system was installed with a multi-tube heat exchanger with each heat transfer area designed for a heat transfer coefficient of condensation between 800 and 1,000 kcal / m ² hr ° C (Fig. 8). .

  As a result, the outlet temperature of each heat exchanger in the heating and dissolving step (II) of the purified terephthalic acid production apparatus using this system was as shown in FIG. 8, and the outlet temperature of the heat exchanger H-5 was 245 ° C.

  50 ml each of the condensed water collected from the flash drum B-0 of Example 3 was collected in four conical tubes for a centrifuge, and the purified terephthalic acid crystal powder was not added (0.0 wt%) and the added amount was 0.05 g (0.1 wt). %), 0.25 g (0.5 wt%), and 0.5 g (1.0 wt%) were shaken well and then set in a centrifuge. After centrifuging at a rotational speed of 7,500 rpm for 5 minutes, the supernatant in the conical tube was collected, and the content of each p-toluic acid was measured.

  The result is shown in FIG. The temperature of the collected supernatant was 55 ° C. It was found that the content of p-toluic acid was reduced to about half or less when the added amount was 0.1% by weight compared to the condensed water without purified terephthalic acid (0.0% by weight).

DESCRIPTION OF SYMBOLS 1 Crude aromatic dicarboxylic acid crystal 2 Solvent water 3 Crude aromatic dicarboxylic acid crystal slurry 4 Control valve 5 Slurry supply line 6 Crude aromatic dicarboxylic acid aqueous solution 7 Purified aromatic dicarboxylic acid aqueous solution 8 Purified aromatic dicarboxylic acid slurry 9 Purified aromatic Dicarboxylic acid crystal 10 Water vapor 11-1 Condensed water 11-2 Recovered condensed water 12 Heated steam introduction line (flow 1)
13 Steam circulation line (flow 3)
14 Excess water vapor discharge line (stream 2), (stream 5)
15 Condensate transfer line (stream 4), (stream 6)
16 Addition aromatic dicarboxylic acid crystal 17 Separation water 18 Separation crystal 19 Crude aromatic dicarboxylic acid production process 20 Separation mother liquor 21 Waste steam 22 Crude terephthalic acid production process 23 Crude terephthalic acid crystal 24 High pressure waste water 25 High pressure hydrogen 26 Ultra high pressure water vapor 27 Purification Aqueous terephthalic acid 28 Purified terephthalic acid crystal slurry 29 Added terephthalic acid crystal 30 Purified terephthalic acid crystal 31 High-pressure drainage 32 Heating unit 33 Deformation heating unit I Slurry adjustment process
II Heating and melting process
III Hydrotreating process
IV Crystallization process V Solid-liquid separation process A Slurry adjustment tank B Flash drum (B-0, B-1, B-2, B-3, B-4, B-5, B-6, B- (N- 1), BN, B- (N + 1))
C Crystallization tank (C-1, C-2, C-3, C-4, C-5, C- (n-1), Cn, C- (n + 1))
D Melting tank H Heat exchanger (H-1, H-2, H-3, H-4, H-5, H-6, H- (N-1), HN, H- (N + 1), HX)
H-0 Preheat heat exchanger P Pump (P-1, P-2, P-3, P-4, P-5)
R Hydrorefining equipment S Solid-liquid separator LC Liquid level controller PC Pressure controller TC Temperature controller

Claims (10)

Using crude aromatic dicarboxylic acid produced by liquid phase oxidation of dialkylbenzene as a raw material,
(I) A slurry adjustment step of mixing a crude aromatic dicarboxylic acid crystal and water to produce a crude aromatic dicarboxylic acid crystal slurry,
(II) Supplying the crude aromatic dicarboxylic acid crystal slurry to a plurality of heat exchangers arranged in series along the slurry supply line, sequentially heating to dissolve the crystal component, and heating and dissolving step to make an aqueous solution,
(III) A hydrorefining step in which the crude aromatic dicarboxylic acid aqueous solution is brought into contact with a catalyst in the presence of hydrogen under high temperature and high pressure to obtain a purified aromatic dicarboxylic acid aqueous solution,
(IV) A plurality of the above purified aromatic dicarboxylic acid aqueous solutions are arranged in series, introduced into a crystallization tank in which the pressure has been lowered stepwise, and released and cooled stepwise to precipitate purified aromatic dicarboxylic acid crystals. A crystallization step for producing a purified aromatic dicarboxylic acid crystal slurry,
(V) a solid-liquid separation step of recovering the purified aromatic dicarboxylic acid crystal by solid-liquid separation of the purified aromatic dicarboxylic acid crystal slurry;
Through which a purified aromatic dicarboxylic acid is produced,
(Flow 1) Water vapor generated by the release pressure of any n-th stage crystallization tank Cn in the crystallization step (IV) is passed through a heated steam introduction line, and any N-th stage in the heating and dissolving step (II). After being introduced into the heating side of the heat exchanger HN and steam-heated, the condensed water flowing down is discharged and stored in the attached flash drum BN.
(Flow 2) Heat exchanger H- (N + x) (x: 1 or more) installed on the downstream side (high temperature side) of the crude aromatic dicarboxylic acid crystal slurry than the arbitrary heat exchanger H-N The pressure control of the flash drum B- (N + x) (x: an integer greater than or equal to 1 indicates the downstream side beyond adjacent) The water vapor released from the pressure controller is supplied to the heating steam introduction line of the heat exchanger H-N and used for heating the crude aromatic dicarboxylic acid crystal slurry.
(Flow 3) The water vapor generated by the release pressure of the condensed water flowing into the attached flash drum BN and the accompanying water vapor are reused for heating the heat exchanger HN via a water vapor circulation line.
(Flow 4) The flash drum B- (N + x) attached to the heat exchanger H- (N + x) installed on the downstream side (high temperature side) of the slurry supply line with respect to the arbitrary heat exchanger H-N. The condensed water collected and accumulated is introduced into the flash drum BN attached to the heat exchanger H-N, and is released to generate water vapor. The generated steam is used for heating the heat exchanger HN through the steam circulation line (stream 3). The remaining condensed water is accumulated in the attached flash drum BN.
(Flow 5) In the heating of the heat exchanger HN, excess water vapor is upstream of the slurry supply line (low temperature) by the pressure control (PC pressure controller) in the attached flash drum BN. The heat exchanger H- (Nx) installed on the side) is discharged and supplied to the heating steam introduction line of the heat exchanger H- (Nx) (where x is an integer equal to or greater than 1 and indicates the upstream side beyond and adjacent).
(Flow 6) The condensed water accumulated in the attached flash drum BN is attached to the upstream (low temperature side) heat exchanger H- (Nx) of the slurry supply line by liquid level control (LC liquid level controller). It is discharged and supplied to a flash drum B- (Nx) (x: an integer of 1 or more, indicating an adjacent side and an upstream side beyond the adjacent side).
A crude fragrance characterized by using a heating / dissolving step (II) comprising at least one heating unit comprising a heat exchanger HN having the flow (flow 1) to (flow 6) and an attached flash drum BN. For purification of group dicarboxylic acids.
The method according to claim 1, wherein the attached flash drum B- (N + x) (x: an integer of 1 or more) installed downstream of the arbitrary heat exchanger H-N on the slurry supply line (high temperature side). (Stream 1), (stream 3), (stream 5) and (stream 6) are not present (stream 2) and / or (stream 4) from (adjacent and downstream downstream). The heat exchanger HN and the attached flash drum with the flow of (stream 1), (stream 3), (flow 5), (flow 6) and (flow 2) or (flow 4) A method for purifying a crude aromatic dicarboxylic acid, comprising using a heating and dissolving step (II) including at least one deformation heating unit made of BN.
2. The method according to claim 1, wherein a heat exchanger H- (N + x) and an attached flash drum B- installed on the downstream side (high temperature side) of the slurry supply line with respect to the arbitrary heat exchanger H-N. (N + x) (where x is an integer greater than or equal to 1 and indicates adjacent and downstream downstream) is provided with (stream 1), (stream 3), (stream 5) and (stream 6) A method for purifying a crude aromatic dicarboxylic acid, characterized by using a heating and dissolving step (II) provided with at least one deformation heating unit.
4. The method according to claim 1, 2, and 3, the plurality of crystallization tanks of the crystallization step (IV) is an n-th stage C-n (n is an integer of 1 or more, and is the highest temperature and high pressure side). The crystallization tank is C-1, and the crystallization tanks that gradually decrease the pressure step by step are C-2, C-3,..., Cn, C- (n + 1)),
The plurality of heat exchangers H in the heating and melting step (II) are the N-th stage heat exchanger HN (N is an integer of 1 or more, the lowest temperature heat exchanger is H-1, and the temperature is increased sequentially. H-2, H-3,..., HN, H- (N + 1))
(Flow 1) Water vapor generated by the release pressure of the final stage crystallization tank C- (n + 1) on the lowest temperature and low pressure side in the crystallization step (IV) is converted into the lowest temperature and low pressure side in the heating and dissolution step (II). It is introduced into the heating side through the heating steam introduction line of the heat exchanger H-1 arranged in the heat exchanger H-1. Subsequently, water vapor generated from each crystallization tank Cn, C- (n-1),..., C-2, C-1 on the high temperature side in turn is the crude aromatic dicarboxylic acid in the heating and dissolving step (II). Corresponding to each heat exchanger H-2, H-3, ..., HN, H- (N + 1) arranged in order of flow direction (from low temperature side to high temperature side) of the slurry supply line of crystal slurry And individually introduced through the heating steam introduction line. The generated steam is heated by steam in each of the heat exchangers H-1, H-2,..., HN, H- (N + 1), and then condensed as flash water B with each heat exchanger. -1, B-2, ..., BN, B- (N + 1) are discharged and stored.
(Flow 2) Heat adjacent to the downstream side (high temperature side) of the slurry supply line from each heat exchanger H-1, H-2, H-3, ..., HN, H- (N + 1) Water vapor released by pressure control (PC pressure regulator) of lash drum B-2, ..., BN, B- (N + 1) with an exchanger is adjacent to each upstream side (low temperature side) Supplied to the heating steam introduction line of heat exchangers H-0, H-1, H-2,. The heat exchanger H-0 is an exhaust heat recovery unit for the supply slurry residual heat.
(Flow 3) Liquid level control of flash drums B-1, B-2,..., BN, B- (N + 1) with a heat exchanger adjacent to the downstream side (high temperature side) of the slurry supply line ( LC level controller), the water vapor generated by the release pressure of the condensed water discharged into each of the attached flash drums B-1, B-2, ..., BN, B- (N + 1) and the above Respective steam accompanying (stream 1) is reused for heating each of the heat exchangers H-1, H-2,..., HN, H- (N + 1) through a steam circulation line. Is done.
(Flow 4) Downstream of the slurry supply line (high temperature side) from the respective heat exchangers H-0, H-1, H-2, H-3, ..., HN, H- (N + 1) ) Adjacent to the heat exchangers H-1, H-2, H-3, ..., HN, H- (N + 1) The respective flash drums B-1, B-2, B-3 , ..., condensed water collected and accumulated in BN, B- (N + 1) is attached to each upstream (low temperature side) flash drum by liquid level control (LC liquid level controller) B-0, B-1, B-2, ..., discharged to BN and release to generate water vapor. The steam generated from each flash drum is used to heat the heat exchangers H-0, H-1, H-2,..., HN through a steam circulation line, and the remaining condensed water is flashed to each of the attached flashes. Accumulated in drums B-0, B-1, B-2, ..., BN. The flash drum B-0 is a flash drum attached to the heat exchanger H-0 or a condensed water recovery tank.
(Flow 5) The water vapor surplus for heating the respective heat exchangers H-1, H-2,..., HN, H- (N + 1) is supplied to the respective flash drums B-1. , B-2, ..., BN, B- (N + 1) pressure control (PC pressure regulator), heat exchangers H-0, H- adjacent to the upstream side of the slurry supply line (low temperature side) 1, H-2,..., HN are discharged to each heating steam introduction line.
(Flow 6) The condensed water accumulated in each of the attached flash drums B-1, B-2,..., BN, B- (N + 1) is liquid level control (LC liquid level controller). Are supplied to the attached flash drums B-0, B-1, B-2,..., BN adjacent to the upstream side (low temperature side) of the slurry supply line.
The crude aromatic dicarboxylic acid crystal slurry comprises heat exchangers H-1, H-2,..., HN and an attached flash drum B-1, each having a heating flow from (Stream 1) to (Stream 6). B-2, ..., BN, a heating unit that sequentially heats from the upstream side (low temperature side) of the slurry supply line, a heat exchanger H- (N + 1) on the most downstream side (high temperature side), and an attached flash drum Using the heating and melting step (II) that constitutes the heating system consisting of the deformation heating unit with B- (N + 1), the crystallization tanks C- (n + 1) and Cn in the crystallization step (IV) A method for purifying a crude aromatic dicarboxylic acid characterized by heating with steam generated from C-2 and C-1.
The method according to claim 1, 2, and 4, wherein the crude aromatic dicarboxylic acid crystal slurry is generated using water vapor generated from the crystallization tank C-1 which is the highest temperature and pressure in the crystallization step (IV). The temperature at which a crude aromatic dicarboxylic acid aqueous solution is formed using a high-temperature (about 300 ° C or higher) heating medium after heating in the heat exchanger H- (N + 1) installed on the downstream side (high-temperature side) of the slurry supply line A method for purifying a crude aromatic dicarboxylic acid characterized by heating to the above.
5. The method according to claim 1, 2, and 4, wherein the condensed water discharged from each of the heat exchanger-provided flash drums is at least the most upstream (low temperature side) of the slurry supply line. A method for purifying crude aromatic dicarboxylic acid, comprising using condensed water and / or water vapor from -1 as a heating medium for the crude aromatic dicarboxylic acid crystal slurry and / or as another heating medium.
5. The method according to claim 1, 2, and 4, wherein condensed water or heat discharged from a flash drum with a heat exchanger installed at a most upstream side (low temperature side) of a slurry supply line of the crude aromatic dicarboxylic acid crystal slurry. Raw material of crude aromatic dicarboxylic acid produced by adding aromatic dicarboxylic acid crystals to the condensed water after collection, separating the separated crystals and separated water into solid and liquid, and then producing the recovered separated crystals by liquid phase oxidation of dialkylbenzene And the recovered separated water is used as a part of water to be mixed with the crude aromatic dicarboxylic acid crystal in the slurry preparation step (I).
5. The method according to claim 1, 2, or 4, wherein the crude aromatic dicarboxylic acid used as a raw material is crude terephthalic acid produced by liquid phase oxidation of para-xylene. Purification method.
Using a crystalline crude organic compound as a raw material,
(I) A slurry adjusting step of mixing the crude organic compound and a solvent to produce a crude organic compound crystal slurry,
(II) supplying the crude organic compound crystal slurry to a plurality of serially arranged heat exchangers along a slurry supply line, sequentially heating to dissolve the crystal component, and heating and dissolving step to obtain a solution;
(III) A purification step in which the crude organic compound solution is purified as it is under high temperature and high pressure to obtain a purified solution,
(IV) A plurality of the purified organic compound solutions are introduced into a crystallization tank in which the pressure is gradually lowered in series, and the purified crystallization tank is depressurized and cooled to precipitate purified organic compound crystals. Crystallization process to produce,
(V) a solid-liquid separation step in which the purified organic compound crystal slurry is subjected to solid-liquid separation to recover purified organic compound crystals;
A method for producing a purified organic compound via
(Flow 1) The solvent vapor generated by the release pressure of the arbitrary n-th stage crystallization tank Cn in the crystallization step (IV) is passed through the heated steam introduction line, and the arbitrary N-th stage in the heating and dissolving step (II). After being introduced into the heating side of the heat exchanger HN and heated by steam, the condensed solvent water flowing down is discharged to the attached flash drum BN and stored.
(Flow 2) Heat exchanger H- (N + x) (x: integer greater than or equal to 1) installed on the downstream side (high temperature side) of the crude organic compound crystal slurry than the arbitrary heat exchanger H-N Pressure control (PC pressure adjustment) of the attached flash drum B- (N + x) (x: an integer greater than or equal to 1 and indicating the downstream side beyond the adjacent) The solvent vapor released from the meter) is supplied to the heating steam introduction line of the heat exchanger H-N and used for heating the crude organic compound crystal slurry (inflow 3) The condensed solvent liquid that has flowed into the attached flash drum BN The solvent vapor entrained in the refrigerant is reused for heating the heat exchanger HN through a solvent vapor circulation line.
(Flow 4) The flash drum B- attached to the heat exchanger H- (N + x) installed on the downstream side (high temperature side) of the crude organic compound crystal slurry rather than the arbitrary heat exchanger H-N The condensed solvent liquid collected and accumulated in (N + x) is introduced into the attached flash drum BN, and the pressure is released to generate solvent vapor. The generated solvent vapor is used for heating the heat exchanger HN through the solvent vapor circulation line (stream 3). The remaining condensed solvent liquid is accumulated in the attached flash drum BN.
(Flow 5) In the heating of the heat exchanger HN, surplus solvent vapor is upstream of the slurry supply line from the heat exchanger HN by pressure control (PC pressure controller) in the attached flash drum BN ( It is discharged and supplied to the heating steam introduction line of the heat exchanger H- (Nx) (x: an integer of 1 or more, indicating the upstream side beyond and adjacent) installed on the low temperature side.
(Flow 6) The condensed solvent liquid accumulated in the attached flash drum BN is converted into a heat exchanger H on the upstream side (low temperature side) of the crude organic compound crystal slurry by liquid level control (LC liquid level controller). -(Nx) attached flash drum B- (Nx) (x: an integer of 1 or more, indicating the adjacent side and the upstream side beyond the adjacent side).
Use of a heating and melting step (II) comprising at least one heating unit comprising a heat exchanger HN having the flow (flow 1) to (flow 6) and an attached flash drum BN. Purification method for organic compounds.
10. The method according to claim 9, wherein a flash drum B- (N + x) provided with a heat exchanger H- (N + x) installed on the downstream side (high temperature side) of the slurry supply line from the heat exchanger H-N. ) (X: an integer greater than or equal to 1 indicates an adjacent and downstream downstream) there is no (stream 2) and / or (stream 4) inlet stream (stream 1), (stream 3), (Stream 5) and (stream 6) flows, or (stream 1), (stream 3), (stream 5), (stream 6) and (stream 2) or (stream 4) A method for purifying a crystalline crude organic compound comprising using a heating and dissolving step (II) comprising at least one deformation heating unit comprising the exchanger HN and an attached flash drum BN.

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