JP4869758B2 - Method for producing high purity terephthalic acid - Google Patents
Method for producing high purity terephthalic acid Download PDFInfo
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- JP4869758B2 JP4869758B2 JP2006085692A JP2006085692A JP4869758B2 JP 4869758 B2 JP4869758 B2 JP 4869758B2 JP 2006085692 A JP2006085692 A JP 2006085692A JP 2006085692 A JP2006085692 A JP 2006085692A JP 4869758 B2 JP4869758 B2 JP 4869758B2
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- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 title claims description 139
- 238000004519 manufacturing process Methods 0.000 title claims description 41
- 238000002425 crystallisation Methods 0.000 claims description 104
- 230000008025 crystallization Effects 0.000 claims description 104
- 239000002002 slurry Substances 0.000 claims description 42
- 238000001816 cooling Methods 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 32
- 238000010438 heat treatment Methods 0.000 claims description 31
- 238000005984 hydrogenation reaction Methods 0.000 claims description 31
- 239000007864 aqueous solution Substances 0.000 claims description 29
- 239000012530 fluid Substances 0.000 claims description 27
- 239000007788 liquid Substances 0.000 claims description 23
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 claims description 18
- 238000007254 oxidation reaction Methods 0.000 claims description 15
- 239000007791 liquid phase Substances 0.000 claims description 13
- 230000003647 oxidation Effects 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000000926 separation method Methods 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims 1
- 239000003054 catalyst Substances 0.000 description 15
- LPNBBFKOUUSUDB-UHFFFAOYSA-N p-toluic acid Chemical compound CC1=CC=C(C(O)=O)C=C1 LPNBBFKOUUSUDB-UHFFFAOYSA-N 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- GOUHYARYYWKXHS-UHFFFAOYSA-N 4-formylbenzoic acid Chemical compound OC(=O)C1=CC=C(C=O)C=C1 GOUHYARYYWKXHS-UHFFFAOYSA-N 0.000 description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 5
- 229910052794 bromium Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 229910017052 cobalt Inorganic materials 0.000 description 5
- 239000010941 cobalt Substances 0.000 description 5
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 239000012736 aqueous medium Substances 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229910001882 dioxygen Inorganic materials 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical compound CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- -1 bromine compound Chemical class 0.000 description 2
- 150000001869 cobalt compounds Chemical class 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- KQNPFQTWMSNSAP-UHFFFAOYSA-N isobutyric acid Chemical compound CC(C)C(O)=O KQNPFQTWMSNSAP-UHFFFAOYSA-N 0.000 description 2
- 150000002697 manganese compounds Chemical class 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000012452 mother liquor Substances 0.000 description 2
- 239000011949 solid catalyst Substances 0.000 description 2
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- NVIVJPRCKQTWLY-UHFFFAOYSA-N cobalt nickel Chemical compound [Co][Ni][Co] NVIVJPRCKQTWLY-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- IUGYQRQAERSCNH-UHFFFAOYSA-N pivalic acid Chemical compound CC(C)(C)C(O)=O IUGYQRQAERSCNH-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 235000019260 propionic acid Nutrition 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 230000002463 transducing effect Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
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Description
本発明は高純度テレフタル酸の製造方法に関し、より詳細には、晶析槽で降圧冷却により発生する蒸気およびこの蒸気の凝縮液を加熱工程に利用する高純度テレフタル酸の製造方法に関する。 The present invention relates to a method for producing high-purity terephthalic acid, and more particularly to a method for producing high-purity terephthalic acid using steam generated by pressure reduction cooling in a crystallization tank and a condensate of this vapor in a heating step.
加圧下、酢酸溶媒中でコバルト、マンガンおよび臭素を含む触媒などの酸化触媒の存在下に、分子状酸素含有ガスによりパラキシレンを液相で酸化するとテレフタル酸（以下、「ＴＡ」とも記す。）の他に、主たる不純物として４−カルボキシベンズアルデヒド（以下、「４−ＣＢＡ」とも記す。）を含む粗テレフタル酸（以下、「ＣＴＡ」とも記す。）が生成する。しかしながら、ポリエステル繊維等の製造には高純度テレフタル酸（以下、「ＰＴＡ」とも記す。）が原料として要求されるため、上記ＣＴＡの精製が必要になる。 Oxidation of para-xylene in the liquid phase with a molecular oxygen-containing gas in the presence of an oxidation catalyst such as a catalyst containing cobalt, manganese, and bromine in an acetic acid solvent under pressure is terephthalic acid (hereinafter also referred to as “TA”). In addition, crude terephthalic acid (hereinafter also referred to as “CTA”) containing 4-carboxybenzaldehyde (hereinafter also referred to as “4-CBA”) as a main impurity is produced. However, since high-purity terephthalic acid (hereinafter also referred to as “PTA”) is required as a raw material for the production of polyester fibers and the like, it is necessary to purify the CTA.
ＣＴＡの精製方法としては水素添加処理が行なわれている。この方法では、ＣＴＡを水に懸濁させたスラリーを加熱して水溶液とし、水素添加触媒の存在下に水素添加処理し、処理液を晶析および固液分離してＰＴＡを製造する。上記の加熱では、水溶液を高温にする必要があるため、多くのエネルギーを必要とする。一方、上記の晶析では、水溶液の温度を降下させることによりテレフタル酸の溶解度を低下させ結晶を析出させている。温度降下の方法としては一般に減圧による方法（以下、「降圧冷却」ともいう。）が採用されている（例えば、特許文献１〜３参照）。この方法は圧力を降下させることにより水の一部を蒸発させ、その蒸発潜熱により水溶液の温度を降下させて過飽和状態にし、テレフタル酸の結晶を析出させる方法である。この降圧冷却では多量の蒸気が発生するため、この蒸気を上記加熱に利用する種々のプロセスが提案されている。
Hydrogenation treatment is performed as a purification method of CTA. In this method, a slurry in which CTA is suspended in water is heated to form an aqueous solution, subjected to hydrogenation treatment in the presence of a hydrogenation catalyst, and the treatment liquid is crystallized and solid-liquid separated to produce PTA. The above heating requires a lot of energy because the aqueous solution needs to have a high temperature. On the other hand, in the above crystallization, the solubility of terephthalic acid is lowered by lowering the temperature of the aqueous solution to precipitate crystals. As a method for lowering the temperature, a method using reduced pressure (hereinafter also referred to as “step-down cooling”) is generally employed (see, for example,
特許文献１では、結晶化工程で発生した蒸気をＣＴＡスラリー中に導入することにより加熱源として利用している。また、特許文献２では、第１晶析帯域で発生する蒸気をＣＴＡスラリーを溶解させるための加熱エネルギーとして利用している。特許文献２の図１では、各晶析槽で発生した蒸気を各熱交換器にそれぞれ導入してＣＴＡスラリーと熱交換し、熱交換後の各蒸気を集めて第１段目の熱交換に利用することは開示されているが、この方法はエネルギー回収効率の観点では十分な方法ではない。さらに、特許文献３では、晶析工程で発生した蒸気をＣＴＡスラリーと熱交換することにより、前記蒸気をＣＴＡスラリーの加熱源の一部として利用し、さらに、この熱交換により前記蒸気が凝縮した凝縮液をＣＴＡを溶解する水系媒体として利用している。しかしながら、上記凝縮液はＣＴＡスラリーの加熱源としてではなく、水系媒体として利用されているため、この方法はエネルギー回収効率の観点では十分な方法ではない。
In
このように、晶析工程において降圧冷却により発生する蒸気をＣＴＡスラリーの加熱源として利用する種々の方法が提案されているが、そのエネルギー回収効率は十分ではなく、降圧冷却により発生する蒸気をより有効に利用できる製造方法の開発が望まれていた。
本発明は、上記のような従来技術に伴う問題を解決しようとするものであって、高純度テレフタル酸の製造において、晶析工程での降圧冷却により発生する蒸気をより有効に利
用し、エネルギー回収効率に優れた高純度テレフタル酸の製造方法を提供することを目的としている。
The present invention is intended to solve the problems associated with the prior art as described above, and in the production of high-purity terephthalic acid, the steam generated by the step-down cooling in the crystallization process is more effectively used, and the energy It aims at providing the manufacturing method of the high purity terephthalic acid excellent in the recovery efficiency.
本発明者は、上記問題点を解決すべく鋭意研究した結果、晶析工程での降圧冷却により発生する蒸気と、この蒸気より高温高圧の蒸気が導入された熱交換器で生成する凝縮液とを含む高温流体を、この熱交換器よりも低温の熱交換器に導入して粗テレフタル酸スラリーを加熱することにより、晶析工程で発生した熱エネルギーを効率的にＣＴＡスラリーの加熱工程に利用することができ、高純度テレフタル酸の製造におけるエネルギー使用量を節減できることを見出し、本発明を完成するに至った。 As a result of earnest research to solve the above problems, the present inventor, as a result, steam generated by step-down cooling in the crystallization process, and a condensate generated in a heat exchanger into which steam at a high temperature and high pressure is introduced from this steam, The heat energy generated in the crystallization process is efficiently used in the heating process of the CTA slurry by introducing the high-temperature fluid containing the heat into the heat exchanger lower in temperature than this heat exchanger and heating the crude terephthalic acid slurry. The inventors have found that the amount of energy used in the production of high-purity terephthalic acid can be saved, and have completed the present invention.
すなわち、本発明に係る高純度テレフタル酸の製造方法は、
（I）パラキシレンの液相酸化によって得られる粗テレフタル酸と水とを混合して粗テレ
フタル酸スラリーを形成する工程、（II）該粗テレフタル酸スラリーを複数の熱交換器で段階的に加熱して溶解させ粗テレフタル酸水溶液を形成する工程、（III）該粗テレフタ
ル酸水溶液を水素添加処理する工程、（IV）水素添加後のテレフタル酸水溶液を複数の晶析槽で段階的に降圧冷却してテレフタル酸を晶析させる工程、（V）得られたテレフタル
酸スラリーを固液分離する工程を含む高純度テレフタル酸の製造方法において、
前記工程（II）が、
工程（IV）において降圧冷却により発生する蒸気を熱交換器に導入して粗テレフタル酸スラリーを加熱する工程（II−Ａ）を少なくとも１つと、
工程（IV）において降圧冷却により発生する蒸気と、該蒸気より高温高圧の蒸気が導入された熱交換器で生成する凝縮液とを含む高温流体を該熱交換器よりも低温の熱交換器に導入して粗テレフタル酸スラリーを加熱する工程（II−Ｂ）を少なくとも１つ含む
ことを特徴とする。
That is, the method for producing high-purity terephthalic acid according to the present invention includes:
(I) A step of mixing crude terephthalic acid obtained by liquid phase oxidation of para-xylene and water to form a crude terephthalic acid slurry, and (II) heating the crude terephthalic acid slurry in stages with a plurality of heat exchangers. (III) Step of hydrogenating the crude terephthalic acid aqueous solution, (IV) Step-by-step cooling of the aqueous terephthalic acid solution after hydrogenation in multiple crystallization tanks In the method for producing high-purity terephthalic acid, including the step of crystallizing terephthalic acid, and (V) solid-liquid separation of the obtained terephthalic acid slurry,
The step (II)
At least one step (II-A) of heating the crude terephthalic acid slurry by introducing steam generated by pressure reduction cooling in the step (IV) into a heat exchanger;
In step (IV), a high-temperature fluid containing steam generated by step-down cooling and a condensate generated in a heat exchanger into which high-temperature and high-pressure steam is introduced is converted into a heat exchanger having a temperature lower than that of the heat exchanger. It includes at least one step (II-B) of introducing and heating the crude terephthalic acid slurry.
前記工程（II−Ａ）のうちの１つは、工程（IV）の晶析槽のうちの最も高温高圧の晶析槽で降圧冷却により発生する蒸気を熱交換器に導入して粗テレフタル酸スラリーを加熱する工程であることが好ましい。 One of the steps (II-A) is a method of introducing crude terephthalic acid by introducing steam generated by step-down cooling in the highest temperature and pressure crystallization tank of the crystallization tank of step (IV) into a heat exchanger. A step of heating the slurry is preferred.
前記工程（II−Ｂ）のうちの少なくとも１つは、前記蒸気と、工程（II−Ａ）で用いた熱交換器で生成する凝縮液とを含む高温流体を該熱交換器よりも低温の熱交換器に導入して粗テレフタル酸スラリーを加熱する工程であることが好ましい。 At least one of the steps (II-B) includes a high-temperature fluid containing the steam and a condensate generated in the heat exchanger used in the step (II-A) at a lower temperature than the heat exchanger. It is preferable to be a step of heating the crude terephthalic acid slurry by introduction into a heat exchanger.
前記工程（II）は、前記工程（II−Ａ）を１つと前記工程（II−Ｂ）を少なくとも１つ含むことが好ましい。
前記工程（IV）において、晶析槽をｎ個（ただし、ｎは２以上の整数であり、最も高温高圧の晶析槽を晶析槽（１）とし、順に低温側に、晶析槽（２）、晶析槽（３）、・・・、晶析槽（ｎ−１）とし、最も低温低圧の晶析槽を晶析槽（ｎ）とする）使用し、
前記工程（II）において、少なくとも、前記晶析槽で降圧冷却により発生する蒸気を加熱源とする熱交換器をｎ個（ただし、最も低温の熱交換器を熱交換器（１）とし、順に高温側に、熱交換器（２）、熱交換器（３）、・・・、熱交換器（ｎ−１）とし、最も高温の熱交換器を熱交換器（ｎ）とする）使用し、
熱交換器（ｎ）には、晶析槽（１）で降圧冷却により発生する蒸気が導入され、
熱交換器（ｉ）には、晶析槽（ｎ−ｉ＋１）で降圧冷却により発生する蒸気と熱交換器（ｉ＋１）で生成する凝縮液とを含む高温流体が導入される（ただし、ｉは１以上ｎ−１以下の整数である）
ことが好ましい。
The step (II) preferably includes one step (II-A) and at least one step (II-B).
In the step (IV), the number of crystallization tanks is n (where n is an integer of 2 or more, the crystallization tank having the highest temperature and pressure is the crystallization tank (1)), and the crystallization tank ( 2), the crystallization tank (3), ..., the crystallization tank (n-1), the lowest temperature and low pressure crystallization tank is the crystallization tank (n)),
In the step (II), at least n heat exchangers using steam generated by pressure reduction cooling in the crystallization tank as a heating source (however, the lowest temperature heat exchanger is the heat exchanger (1), and in order) On the high temperature side, use heat exchanger (2), heat exchanger (3), ..., heat exchanger (n-1), and use the hottest heat exchanger as heat exchanger (n). ,
In the heat exchanger (n), steam generated by pressure reduction cooling in the crystallization tank (1) is introduced,
The heat exchanger (i) is introduced with a high-temperature fluid containing steam generated by pressure reduction cooling in the crystallization tank (n−i + 1) and condensate generated in the heat exchanger (i + 1) (where i is (It is an integer from 1 to n-1)
It is preferable.
本発明によると、高純度テレフタル酸の製造において、晶析工程で発生した熱エネルギーを効率的にＣＴＡスラリーの加熱工程に利用することができ、エネルギー使用量を節減できる。 According to the present invention, in the production of high-purity terephthalic acid, the heat energy generated in the crystallization process can be efficiently used for the heating process of the CTA slurry, and the amount of energy used can be saved.
本発明に係る高純度テレフタル酸の製造方法は、（I）パラキシレンの液相酸化によっ
て得られる粗テレフタル酸と水とを混合して粗テレフタル酸スラリーを形成する工程、（II）該粗テレフタル酸スラリーを複数の熱交換器で段階的に加熱して溶解させ粗テレフタル酸水溶液を形成する工程、（III）該粗テレフタル酸水溶液を水素添加処理する工程、
（IV）水素添加後の粗テレフタル酸水溶液を複数の晶析槽で段階的に降圧冷却してテレフタル酸を晶析させる工程、（V）得られたテレフタル酸スラリーを固液分離する工程を含
む。
The method for producing high-purity terephthalic acid according to the present invention comprises (I) a step of mixing crude terephthalic acid obtained by liquid phase oxidation of paraxylene and water to form a crude terephthalic acid slurry, (II) the crude terephthalic acid A step of heating and dissolving the acid slurry stepwise in a plurality of heat exchangers to form a crude terephthalic acid aqueous solution, (III) a step of hydrogenating the crude terephthalic acid aqueous solution,
(IV) includes a step of stepwise cooling the crude terephthalic acid aqueous solution after hydrogenation in a plurality of crystallization tanks to crystallize terephthalic acid, and (V) a step of solid-liquid separation of the obtained terephthalic acid slurry. .
（I）スラリー形成工程：
この工程では、パラキシレンの液相酸化によって得られる粗テレフタル酸と水とを混合して粗テレフタル酸スラリーを形成する。パラキシレンの液相酸化は、一般にテレフタル酸の製造に用いられる酸化反応器により実施することができる。酸化反応器は、パラキシレン等の原料、触媒、溶媒を収容し、これらの原料等を補給しながら空気を吹込んで連続液相酸化を行うことができるものが好ましい。
(I) Slurry forming step:
In this step, a crude terephthalic acid slurry is formed by mixing crude terephthalic acid obtained by liquid phase oxidation of para-xylene and water. The liquid phase oxidation of paraxylene can be carried out in an oxidation reactor generally used for the production of terephthalic acid. The oxidation reactor preferably contains a raw material such as para-xylene, a catalyst, and a solvent, and can perform continuous liquid phase oxidation by blowing air while replenishing these raw materials.
上記パラキシレンの液相酸化は通常、溶媒および触媒を用いて行われる。前記溶媒としては、酢酸、プロピオン酸、ｎ−酪酸、イソ酪酸、ｎ−吉草酸、トリメチル酢酸、カプロン酸などの脂肪酸、あるいはこれらと水との混合物を例示できる。前記触媒としては、重金属、臭素、およびこれらの化合物が挙げられ、重金属としてはニッケル、コバルト、鉄、クロム、マンガン等が挙げられる。これらの触媒は、好ましくは反応系に溶解する形で使用される。前記触媒としては、コバルト化合物とマンガン化合物と臭素化合物とを併用することが好ましく、コバルト化合物の使用量は溶媒に対してコバルト換算で通常１０〜１０，０００ｐｐｍ、好ましくは１００〜３０００ｐｐｍである。また、マンガン化合物はコバルトに対するマンガンの原子比で０．００１〜１０が好ましく、臭素化合物はコバルトに対する臭素の原子比で０．１〜１０が好ましい。 The liquid phase oxidation of paraxylene is usually performed using a solvent and a catalyst. Examples of the solvent include fatty acids such as acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, trimethylacetic acid, caproic acid, and mixtures of these with water. Examples of the catalyst include heavy metals, bromine, and compounds thereof. Examples of heavy metals include nickel, cobalt, iron, chromium, manganese, and the like. These catalysts are preferably used in the form of being dissolved in the reaction system. As said catalyst, it is preferable to use a cobalt compound, a manganese compound, and a bromine compound together, and the usage-amount of a cobalt compound is 10-10,000 ppm normally in conversion of cobalt with respect to a solvent, Preferably it is 100-3000 ppm. Further, the manganese compound preferably has an atomic ratio of manganese to cobalt of 0.001 to 10, and the bromine compound preferably has an atomic ratio of bromine to cobalt of 0.1 to 10.
パラキシレンの液相酸化は通常、分子状酸素含有ガスを用いて行われる。このような酸素含有ガスとしては通常、酸素を不活性ガスで稀釈した希釈酸素ガスが用いられ、例えば空気や酸素を富化した空気が使用される。酸化反応の温度は通常１５０〜２７０℃、好ましくは１７０〜２２０℃であり、圧力は少なくとも反応温度において混合物が液相を保持できる圧力以上であり、通常０．５〜４ＭＰａ（ゲージ圧）である。さらに反応時間は装置の大きさ等によるが、滞留時間として通常２０分〜１８０分程度である。反応系内の水分濃度は通常３〜３０重量％であり、好ましくは５〜１５重量％である。 The liquid phase oxidation of para-xylene is usually performed using a molecular oxygen-containing gas. As such an oxygen-containing gas, a diluted oxygen gas obtained by diluting oxygen with an inert gas is usually used. For example, air or air enriched with oxygen is used. The temperature of the oxidation reaction is usually 150 to 270 ° C., preferably 170 to 220 ° C., and the pressure is at least the pressure at which the mixture can maintain a liquid phase at the reaction temperature, and usually 0.5 to 4 MPa (gauge pressure). . Further, although the reaction time depends on the size of the apparatus, etc., the residence time is usually about 20 minutes to 180 minutes. The water concentration in the reaction system is usually 3 to 30% by weight, preferably 5 to 15% by weight.
上記の液相酸化反応により得られたＣＴＡは、固液分離により液相酸化反応における母液から分離して回収される。このＣＴＡと水とを混合槽において混合してＣＴＡスラリーを形成する。上記混合槽は一般にテレフタル酸の製造に用いられるものを使用することができる。上記ＣＴＡスラリーのＣＴＡ濃度は、通常１０〜４０重量％、好ましくは２０〜３０重量％である。 CTA obtained by the liquid phase oxidation reaction is separated and recovered from the mother liquor in the liquid phase oxidation reaction by solid-liquid separation. The CTA and water are mixed in a mixing tank to form a CTA slurry. The said mixing tank can use what is generally used for manufacture of a terephthalic acid. The CTA concentration of the CTA slurry is usually 10 to 40% by weight, preferably 20 to 30% by weight.
（II）水溶液形成工程：
この工程では、上記ＣＴＡスラリーを複数の熱交換器で段階的に加熱してＣＴＡを溶解し、ＣＴＡ水溶液を形成する。熱交換器としては、一般にテレフタル酸の製造に用いられるものを用いることができる。前記熱交換器のうちの少なくとも１つには、後述する工程（IV）の晶析槽で降圧冷却により発生する蒸気が導入され〔工程（II−Ａ）〕、残りの熱
交換器のうちの少なくとも１つには、後述する工程（IV）の晶析槽で降圧冷却により発生する蒸気と、この熱交換器よりも高温の熱交換器で生成する凝縮液とを含む高温流体が導入される〔工程（II−Ｂ）〕。この蒸気および高温流体が上記ＣＴＡスラリーと熱交換して上記ＣＴＡスラリーが加熱され、蒸気および高温流体は高圧の凝縮液となり、通常、より低温の熱交換器の加熱源として利用する。特に、工程（II−Ａ）の熱交換器に導入された蒸気が凝縮した凝縮液を、圧力を降圧させた後、工程（IV）の晶析槽で発生した蒸気に導入して高温流体を形成し、工程（II−Ａ）の熱交換器よりも低温の熱交換器に導入される。降圧させた凝縮液の圧力は、凝縮液を導入する蒸気の圧力と同程度となる。
(II) Aqueous solution formation process:
In this step, the CTA slurry is heated stepwise by a plurality of heat exchangers to dissolve the CTA and form a CTA aqueous solution. As a heat exchanger, what is generally used for manufacture of terephthalic acid can be used. At least one of the heat exchangers is introduced with steam generated by step-down cooling in the crystallization tank of step (IV) described later [step (II-A)], and the remaining heat exchangers At least one is introduced with a high-temperature fluid containing steam generated by step-down cooling in the crystallization tank in step (IV), which will be described later, and a condensate generated in a heat exchanger having a temperature higher than that of the heat exchanger. [Step (II-B)]. The steam and the high-temperature fluid exchange heat with the CTA slurry to heat the CTA slurry, and the steam and the high-temperature fluid become high-pressure condensate, and are usually used as a heat source for a lower-temperature heat exchanger. In particular, the condensate obtained by condensing the steam introduced into the heat exchanger in the step (II-A) is reduced in pressure, and then introduced into the steam generated in the crystallization tank in the step (IV) to introduce a high-temperature fluid. And is introduced into a heat exchanger having a temperature lower than that of the heat exchanger in the step (II-A). The pressure of the reduced condensate is approximately the same as the pressure of the steam introducing the condensate.
上記工程（II−Ａ）は、エネルギー効率の観点から、工程（II）に１つだけ含まれることが好ましい。
上記工程（II−Ａ）および（II−Ｂ）における加熱温度は、工程（IV）で発生する蒸気の温度によって決定される。また、導入される蒸気および高温流体の圧力も工程（IV）で発生する蒸気の圧力によって決定される。
It is preferable that only one step (II-A) is included in step (II) from the viewpoint of energy efficiency.
The heating temperature in the steps (II-A) and (II-B) is determined by the temperature of the steam generated in step (IV). Further, the pressure of the introduced steam and the high-temperature fluid is also determined by the pressure of the steam generated in the step (IV).
この工程では、ＣＴＡを十分に溶解するために、ＣＴＡ水溶液は通常２３０℃以上、好ましくは２４０〜３００℃まで加熱される。このとき、工程（IV）で発生する蒸気を利用する上記熱交換器以外に、他の経路の高温流体を利用する熱交換器やヒーターなどの他の加熱器を使用してもよい〔工程（II−Ｃ）〕。この工程（II−Ｃ）は、上記工程（II−Ａ）および（II−Ｂ）の前に、予備加熱工程として設けられていてもよいし、あるいは、上記工程（II−Ａ）および（II−Ｂ）の後に、後加熱工程として設けられていてもよい。加熱時の系内の圧力は、水溶液を実質的に液相に保持できる圧力以上であれば特に制限はないが、通常１〜１１ＭＰａ（ゲージ圧）好ましくは３〜９ＭＰａ（ゲージ圧）である。 In this step, in order to sufficiently dissolve CTA, the CTA aqueous solution is usually heated to 230 ° C. or higher, preferably 240 to 300 ° C. At this time, in addition to the heat exchanger using the steam generated in the step (IV), another heater such as a heat exchanger or a heater using a high-temperature fluid in another path may be used [step ( II-C)]. This step (II-C) may be provided as a preheating step before the above steps (II-A) and (II-B), or alternatively, the above steps (II-A) and (II) -B) may be provided as a post-heating step. The pressure in the system at the time of heating is not particularly limited as long as it is equal to or higher than the pressure at which the aqueous solution can be substantially maintained in the liquid phase, but is usually 1 to 11 MPa (gauge pressure), preferably 3 to 9 MPa (gauge pressure).
このようにして調製されたＣＴＡ水溶液の濃度は、上記ＣＴＡスラリーの濃度によって決定され、通常１０〜４０重量％、好ましくは２０〜３０重量％である。
（III）水素添加処理工程：
この工程では、上記ＣＴＡ水溶液を水素添加反応槽に導入して水素添加処理を施し、ＣＴＡ水溶液に含まれる４−ＣＢＡを４−メチル安息香酸（４−ＭＢＡ）に還元する。
The concentration of the CTA aqueous solution thus prepared is determined by the concentration of the CTA slurry, and is usually 10 to 40% by weight, preferably 20 to 30% by weight.
(III) Hydrogenation process:
In this step, the CTA aqueous solution is introduced into a hydrogenation reactor and subjected to hydrogenation treatment, and 4-CBA contained in the CTA aqueous solution is reduced to 4-methylbenzoic acid (4-MBA).
上記水素添加反応槽は、水素添加触媒が充填された触媒層を有し、触媒とＣＴＡ水溶液とが接触した状態で水素を供給できるものであれば、その形状、構造等は特に制限されない。好ましい水素添加反応槽としては、固形の触媒が充填された固定触媒層を内部に有し、この触媒層にＣＴＡ水溶液を通液できるように水溶液導入路および水溶液導出路を有し、さらに水素を供給できるように水素供給路を有するものが挙げられる。ＣＴＡ水溶液の通液方向は制限されず、上向流でも下向流でもよいが、下向流で通液することが好ましく、このために水溶液導入路が水素添加反応槽の上部に、水溶液導出路が下部に設けられていることが好ましい。また、水素は上部から供給されることが好ましく、このために水素供給路が水素添加反応槽の上部に設けられていることが好ましい。 If the said hydrogenation reaction tank has a catalyst layer filled with the hydrogenation catalyst and can supply hydrogen in the state which the catalyst and CTA aqueous solution contacted, the shape, structure, etc. will not be restrict | limited in particular. A preferable hydrogenation reaction tank has a fixed catalyst layer filled with a solid catalyst inside, an aqueous solution introduction path and an aqueous solution outlet path so that a CTA aqueous solution can be passed through the catalyst layer, and hydrogen is further supplied. The thing which has a hydrogen supply path so that it can supply is mentioned. The flow direction of the CTA aqueous solution is not limited and may be an upward flow or a downward flow. However, it is preferable that the CTA aqueous solution flow in the downward flow. For this purpose, the aqueous solution introduction path is formed above the hydrogenation reaction tank. It is preferable that the path is provided in the lower part. Moreover, it is preferable that hydrogen is supplied from the upper part, and for this purpose, it is preferable that a hydrogen supply path is provided in the upper part of the hydrogenation reaction tank.
水素添加触媒としては、従来から用いられているものが使用でき、例えばパラジウム、ルテニウム、ロジウム、オスミウム、イリジウム、白金、白金黒、パラジウム黒、鉄、コバルト−ニッケル等が挙げられるが、固定層を形成できるようにこれらを担体、好ましくは活性炭等の吸着性の担体に担持した固形触媒が好ましい。 As the hydrogenation catalyst, those conventionally used can be used, such as palladium, ruthenium, rhodium, osmium, iridium, platinum, platinum black, palladium black, iron, cobalt-nickel, etc. A solid catalyst in which these are supported on an adsorbent carrier such as activated carbon so that they can be formed is preferable.
具体的な水素添加処理方法としては、たとえば、ＣＴＡ水溶液を水素添加反応槽に導入し、触媒層を通過させながら、水素ガスをＣＴＡ水溶液中の４−ＣＢＡの通常１．５倍モル以上、好ましくは２倍モル以上の流量で供給して水素添加を行なうことが望ましい。水素添加時の水素分圧は通常０．０５ＭＰａ以上、好ましくは０．０５〜２ＭＰａである。この水素添加処理により、ＣＴＡ中の４−ＣＢＡは水溶性の４−ＭＢＡに還元され、一方
、ＴＡは水に難溶性であるため、通常３００℃以下、好ましくは１００〜２８０℃の温度で晶析および固液分離を行なうことにより、ＣＴＡ水溶液から４−ＭＢＡを分離してＰＴＡを得ることができる。
As a specific hydrogenation treatment method, for example, a CTA aqueous solution is introduced into a hydrogenation reaction tank, and while passing through the catalyst layer, hydrogen gas is usually 1.5 times mol or more of 4-CBA in the CTA aqueous solution, preferably It is desirable to perform hydrogenation by supplying at a flow rate of 2 times mole or more. The hydrogen partial pressure at the time of hydrogenation is usually 0.05 MPa or more, preferably 0.05 to 2 MPa. By this hydrogenation treatment, 4-CBA in CTA is reduced to water-soluble 4-MBA, while TA is hardly soluble in water, so that it is usually at a temperature of 300 ° C. or less, preferably 100 to 280 ° C. By performing precipitation and solid-liquid separation, 4-MBA can be separated from the CTA aqueous solution to obtain PTA.
（IV）晶析工程：
この工程では、上記水素添加後のＣＴＡ水溶液（以下、「ＣＴＡ水添処理液」という）を複数の晶析槽で段階的に降圧冷却してＴＡを晶析させる。晶析槽としては、一般にテレフタル酸の製造に用いられるものを用いることができる。具体的には、上記ＣＴＡ水添処理液の圧力より低い圧力条件に設定した晶析槽に上記ＣＴＡ水添処理液を導入し、ＣＴＡ水添処理液の圧力を減圧させ、これに伴いＣＴＡ水添処理液を冷却させる（降圧冷却）方法である。本発明では、複数の晶析槽を用いてＣＴＡ水添処理液の圧力を段階的に減圧し、これに伴ってＣＴＡ水添処理液の温度を段階的に低下させる。これにより、テレフタル酸が晶析され、ＴＡスラリーが形成される。
(IV) Crystallization process:
In this step, TA is crystallized by stepwise cooling the CTA aqueous solution after hydrogenation (hereinafter referred to as “CTA hydrogenation solution”) stepwise in a plurality of crystallization tanks. As the crystallization tank, those generally used for the production of terephthalic acid can be used. Specifically, the CTA hydrogenation treatment liquid is introduced into a crystallization tank set to a pressure condition lower than the pressure of the CTA hydrogenation treatment liquid, and the pressure of the CTA hydrogenation treatment liquid is reduced. This is a method of cooling the treatment liquid (step-down cooling). In the present invention, the pressure of the CTA hydrogenation treatment liquid is reduced stepwise using a plurality of crystallization tanks, and the temperature of the CTA hydrogenation treatment liquid is lowered stepwise accordingly. Thereby, terephthalic acid is crystallized and TA slurry is formed.
上記のように降圧冷却を行なうと、各晶析槽においてＣＴＡ水添処理液の中の水媒体の一部が気化して蒸気が発生する。この蒸気は、上述したように、前記工程（II−Ａ）および（II−Ｂ）の熱交換器に導入され、ＣＴＡスラリーの加熱源として利用される。特に、上記晶析槽のうち、最も高温高圧の晶析槽で降圧冷却により発生する蒸気は、熱交換器で生成する凝縮液を導入することなく、単独で工程（II）の熱交換器に導入することがエネルギー効率の観点から好ましい。 When the step-down cooling is performed as described above, a part of the aqueous medium in the CTA hydrogenation treatment liquid is vaporized and vapor is generated in each crystallization tank. As described above, this steam is introduced into the heat exchangers of steps (II-A) and (II-B) and used as a heating source for the CTA slurry. In particular, among the above crystallization tanks, the steam generated by the pressure reduction cooling in the highest temperature and high pressure crystallization tank alone is not introduced into the heat exchanger of the step (II) without introducing the condensate generated in the heat exchanger. It is preferable to introduce from the viewpoint of energy efficiency.
降圧冷却により冷却されたＣＴＡ水添処理液および発生した蒸気の温度は、各晶析槽において降圧冷却時の圧力を調整することにより適宜決定される。
（V）固液分離工程：
この工程では、上記ＴＡスラリーを固液分離して母液からＰＴＡを分離回収する。固液分離は、濾過機や遠心分離機など、一般にテレフタル酸の製造に用いられる固液分離装置を用いて実施することができる。
The temperature of the CTA hydrogenation treatment liquid cooled by the step-down cooling and the generated steam are appropriately determined by adjusting the pressure during the step-down cooling in each crystallization tank.
(V) Solid-liquid separation process:
In this step, the TA slurry is solid-liquid separated to separate and recover PTA from the mother liquor. Solid-liquid separation can be carried out using a solid-liquid separation apparatus such as a filter or a centrifuge, which is generally used for producing terephthalic acid.
（晶析槽で発生する蒸気およびその凝縮液の具体的な利用方法）
上述したように、本発明では、工程（IV）で発生した蒸気を工程（II−Ａ）および（II−Ｂ）の加熱工程に利用する。
(Specific use of vapor generated in the crystallization tank and its condensate)
As described above, in the present invention, the steam generated in the step (IV) is used for the heating step in the steps (II-A) and (II-B).
以下、工程（IV）において、晶析槽をｎ個（ｎは２以上の整数）使用し、工程（II）において、このｎ個の晶析槽から発生する蒸気を加熱源として利用する熱交換器をｎ個使用する場合について説明する。 Hereinafter, in the step (IV), n crystallization tanks (n is an integer of 2 or more) are used, and in the step (II), heat generated from the steam generated from the n crystallization tanks is used as a heat source. The case where n pieces are used will be described.
最も高温高圧の晶析槽を晶析槽（１）とし、順に低温側に、晶析槽（２）、晶析槽（３）、・・・、晶析槽（ｎ−１）とし、最も低温低圧の晶析槽を晶析槽（ｎ）とする。また、最も低温の熱交換器を熱交換器（１）とし、順に高温側に、熱交換器（２）、熱交換器（３）、・・・、熱交換器（ｎ−１）とし、最も高温の熱交換器を熱交換器（ｎ）とする。 The highest temperature and pressure crystallization tank is the crystallization tank (1), and the crystallization tank (2), the crystallization tank (3),. Let the low-temperature and low-pressure crystallization tank be a crystallization tank (n). Moreover, let the heat exchanger (1) the lowest temperature be a heat exchanger (1), and in order of the high temperature side, heat exchanger (2), heat exchanger (3), ..., heat exchanger (n-1), The hottest heat exchanger is defined as a heat exchanger (n).
通常、最も高温高圧の晶析槽（１）で降圧冷却により発生する蒸気は、エネルギー効率の観点から、熱交換器で生成する凝縮液を導入せずに、単独で熱交換器（ｎ）に導入することが好ましい。 Normally, the steam generated by the pressure reduction cooling in the highest temperature and high pressure crystallization tank (1) is introduced into the heat exchanger (n) alone without introducing the condensate produced in the heat exchanger from the viewpoint of energy efficiency. It is preferable to introduce.
また、低温側からｉ番目（ｉは１以上ｎ−１以下の整数）の熱交換器（ｉ）には、熱交換器（ｉ）よりも高温の熱交換器（ｉ＋１）で生成する高圧の凝縮液を、低温側からｉ番目の晶析槽で降圧冷却により発生する蒸気に導入して形成された高温流体を、加熱源として導入する。ここで、低温側からｉ番目の晶析槽は高温側から数えるとｎ−ｉ＋１番目で
ある。したがって、低温側からｉ番目の熱交換器（ｉ）には、晶析槽（ｎ−ｉ＋１）で発生した蒸気と熱交換器（ｉ＋１）で生成する高圧の凝縮液との高温流体が導入される。この高温流体を形成する場合、凝縮液の圧力を降圧した後、該凝縮液が生成された熱交換器よりも低圧低温の熱交換器に接続する蒸気配管に該凝縮液を導入することが好ましい。
In addition, the i-th heat exchanger (i) from the low temperature side (i is an integer of 1 to n-1) has a high pressure generated by the heat exchanger (i + 1) that is higher in temperature than the heat exchanger (i). A high-temperature fluid formed by introducing the condensate into steam generated by pressure reduction cooling in the i-th crystallization tank from the low temperature side is introduced as a heating source. Here, the i-th crystallization tank from the low temperature side is the (n−i + 1) th when counted from the high temperature side. Therefore, the i-th heat exchanger (i) from the low temperature side is introduced with a high-temperature fluid of the steam generated in the crystallization tank (n−i + 1) and the high-pressure condensate generated in the heat exchanger (i + 1). The When forming this high-temperature fluid, it is preferable to introduce the condensate into a steam pipe connected to a low-temperature and low-temperature heat exchanger after reducing the pressure of the condensate than the heat exchanger in which the condensate was generated. .
なお、前者の工程は工程（II−Ａ）に相当し、後者の工程は工程（II−Ｂ）に相当する。図１はこれらの工程を含む製造方法に用いられる製造装置（ｎ＝４の場合）の概略図である。 The former process corresponds to the process (II-A), and the latter process corresponds to the process (II-B). FIG. 1 is a schematic view of a manufacturing apparatus (in the case of n = 4) used in a manufacturing method including these steps.
本発明の製造方法では、工程（II−Ａ）および（II−Ｂ）は上記工程に限定されず、たとえば、工程（II−Ｂ）が以下の工程であってもよい。
低温側からｉ番目（ｉは１以上ｎ−１以下の整数）の熱交換器（ｉ）には、熱交換器（ｉ）よりも高温の熱交換器（ｉ＋２）で生成する高圧の凝縮液を、低温側からｉ番目の晶析槽で降圧冷却により発生する蒸気に導入して形成された高温流体を、加熱源として導入してもよい。上記と同様に、低温側からｉ番目の晶析槽は高温側から数えるとｎ−ｉ＋１番目であるから、低温側からｉ番目の熱交換器（ｉ）には、晶析槽（ｎ−ｉ＋１）で発生した蒸気と熱交換器（ｉ＋２）で生成する高圧の凝縮液との高温流体を導入してもよい。この場合も、高温流体を形成する際には、凝縮液の圧力を降圧した後、該凝縮液が生成された熱交換器よりも低圧低温の熱交換器に接続する蒸気配管に該凝縮液を導入することが好ましい。
In the production method of the present invention, steps (II-A) and (II-B) are not limited to the above steps, and for example, step (II-B) may be the following steps.
The i-th heat exchanger (i) from the low temperature side (i is an integer of 1 to n-1) has a high-pressure condensate generated in the heat exchanger (i + 2) that is higher in temperature than the heat exchanger (i). May be introduced as a heating source by introducing a high-temperature fluid into the steam generated by the pressure reduction cooling in the i-th crystallization tank from the low temperature side. Similarly to the above, since the i-th crystallization tank from the low temperature side is the (ni + 1) th when counted from the high temperature side, the i-th heat exchanger (i) from the low temperature side has the crystallization tank (n-i + 1). ) And a high-temperature fluid of high-pressure condensate generated in the heat exchanger (i + 2) may be introduced. In this case as well, when forming the high-temperature fluid, after reducing the pressure of the condensate, the condensate is put into a steam pipe connected to a heat exchanger having a lower pressure and lower temperature than the heat exchanger in which the condensate is generated. It is preferable to introduce.
図２はこの工程を含む製造方法に用いられる製造装置（ｎ＝４の場合）の概略図である。
（製造装置）
本発明に係る高純度テレフタル酸の製造方法は、混合槽、複数の熱交換器、反応槽、複数の晶析槽および固液分離装置がこの順で直列に接続された、高純度テレフタル酸の製造装置であって、熱交換器と晶析槽とが以下のように配管で接続された製造装置を使用して行うことができる。
FIG. 2 is a schematic view of a manufacturing apparatus (when n = 4) used in the manufacturing method including this process.
(Manufacturing equipment)
The method for producing high-purity terephthalic acid according to the present invention comprises a mixing tank, a plurality of heat exchangers, a reaction tank, a plurality of crystallization tanks, and a solid-liquid separation device connected in series in this order. It is a manufacturing apparatus, Comprising: It can carry out using the manufacturing apparatus with which the heat exchanger and the crystallization tank were connected by piping as follows.
前記熱交換器のうちの少なくとも１つは、晶析槽で発生する蒸気が導入されるように当該晶析槽と接続されている。
また、残りの熱交換器のうちの少なくとも１つは、蒸気配管により晶析槽と接続されており、この蒸気配管の途中にはこの熱交換器よりも高温高圧の熱交換器に接続された凝縮液配管が接続されており、この凝縮液配管の途中には圧力調整弁が設けられている。これにより、晶析槽で発生する蒸気に熱交換器で生成する凝縮液が導入されて高温流体が形成され、この高温流体が該熱交換器よりも低温低圧の熱交換器に導入される。
At least one of the heat exchangers is connected to the crystallization tank so that steam generated in the crystallization tank is introduced.
Further, at least one of the remaining heat exchangers is connected to the crystallization tank by a steam pipe, and is connected to a heat exchanger having a higher temperature and a higher pressure than the heat exchanger in the middle of the steam pipe. A condensate pipe is connected, and a pressure regulating valve is provided in the middle of the condensate pipe. Thereby, the condensate produced | generated with a heat exchanger is introduce | transduced into the vapor | steam which generate | occur | produces in a crystallization tank, a high temperature fluid is formed, and this high temperature fluid is introduce | transduced into a heat exchanger of low temperature and low pressure rather than this heat exchanger.
前記熱交換器のうち、最も高温の熱交換器は、最も高温高圧の晶析槽と接続されていることが、エネルギー効率の観点から好ましい。
また、前記熱交換器の少なくとも１つ（以下、この熱交換器を「熱交換器α」という）は晶析槽（以下、この晶析槽を「晶析槽α」という）と接続され、熱交換器αよりも低温低圧の熱交換器のうちの少なくとも１つ（以下、この熱交換器を「熱交換器β」という）は、晶析槽αと異なる晶析槽（以下、この晶析槽を「晶析槽β」という）と蒸気配管により接続され、この蒸気配管の途中には熱交換器αに接続された凝縮液配管が接続されており、この凝縮液配管の途中には圧力調整弁が設けられていることが好ましい。
Of the heat exchangers, the highest temperature heat exchanger is preferably connected to the highest temperature and pressure crystallization tank from the viewpoint of energy efficiency.
In addition, at least one of the heat exchangers (hereinafter, this heat exchanger is referred to as “heat exchanger α”) is connected to a crystallization tank (hereinafter, this crystallization tank is referred to as “crystallization tank α”), At least one of the heat exchangers at a lower temperature and lower pressure than the heat exchanger α (hereinafter, this heat exchanger is referred to as “heat exchanger β”) has a crystallization tank (hereinafter referred to as this crystallization tank) different from the crystallization tank α. The crystallization tank is referred to as “crystallization tank β” by a steam pipe, and a condensate pipe connected to the heat exchanger α is connected in the middle of this steam pipe, and in the middle of this condensate pipe It is preferable that a pressure regulating valve is provided.
さらに、本発明の製造装置には、晶析槽のみと接続している熱交換器が１つであることがエネルギー効率の観点から好ましい。
上記のように、ｎ個の晶析槽とｎ個の熱交換器を有する製造装置としては、熱交換器（ｎ）が晶析槽（１）と配管により接続され、熱交換器（ｉ）が蒸気配管により晶析槽（ｎ
−ｉ＋１）と接続され、この蒸気配管の途中に熱交換器（ｉ＋１）に接続された凝縮液配管が接続されている（ただし、ｉは１以上ｎ−１以下の整数である）製造装置が挙げられる。凝縮液配管には、圧力調整弁が設けられていることが好ましい。図１はこの製造装置（ｎ＝４の場合）の概略図である。
Furthermore, it is preferable from the viewpoint of energy efficiency that the production apparatus of the present invention has one heat exchanger connected only to the crystallization tank.
As described above, as a production apparatus having n crystallization tanks and n heat exchangers, the heat exchanger (n) is connected to the crystallization tank (1) by piping, and the heat exchanger (i). The crystallization tank (n
-I + 1), and a condensate pipe connected to the heat exchanger (i + 1) is connected in the middle of the steam pipe (where i is an integer from 1 to n-1). Can be mentioned. The condensate pipe is preferably provided with a pressure adjusting valve. FIG. 1 is a schematic view of this manufacturing apparatus (when n = 4).
また、熱交換器（ｎ）が晶析槽（１）と配管により接続され、熱交換器（ｉ）が蒸気配管により晶析槽（ｎ−ｉ＋１）と接続され、この蒸気配管の途中に熱交換器（ｉ＋２）に接続された凝縮液配管が接続されている（ただし、ｉは１以上ｎ−１以下の整数である）製造装置も挙げられる。この場合にも、凝縮液配管には、圧力調整弁が設けられていることが好ましい。図２はこの製造装置（ｎ＝４の場合）の概略図である。 Further, the heat exchanger (n) is connected to the crystallization tank (1) by piping, and the heat exchanger (i) is connected to the crystallization tank (ni + 1) by steam piping. A condensate pipe connected to the exchanger (i + 2) is connected (where i is an integer of 1 to n-1). Also in this case, it is preferable that the condensate pipe is provided with a pressure adjusting valve. FIG. 2 is a schematic view of this manufacturing apparatus (when n = 4).
［実施例］
以下、本発明を実施例により、さらに詳細に説明するが、本発明は、この実施例により何ら限定されるものではない。
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by this Example.
［比較例１］
図３に示す４個の熱交換器と４個の晶析槽とを有する製造装置（ｎ＝４）を使用して、表１に示す条件で、ＣＴＡスラリーを加熱し、得られたＣＴＡ水溶液を水素添加処理し、得られたＣＴＡ処理液を降圧冷却した場合におけるエネルギー効率を評価した。エネルギー効率は熱交換器で生成した凝縮液を降圧する際に生じるエクセルギーロスで評価した。
[Comparative Example 1]
The CTA aqueous solution obtained by heating the CTA slurry under the conditions shown in Table 1 using a production apparatus (n = 4) having four heat exchangers and four crystallization tanks shown in FIG. Was subjected to hydrogenation treatment, and the energy efficiency was evaluated when the obtained CTA treatment liquid was cooled under reduced pressure. The energy efficiency was evaluated by the exergy loss that occurs when the condensate produced by the heat exchanger is depressurized.
第一晶析槽（ｉ＝１）で発生した蒸気の温度は２２０℃、圧力は２．３ＭＰａであり、この蒸気を第四熱交換器（ｉ＝４）に導入した。第二晶析槽（ｉ＝２）で発生した蒸気の温度２０７℃、圧力は１．８ＭＰａであり、この蒸気を第三熱交換器（ｉ＝３）に導入した。第三晶析槽（ｉ＝３）で発生した蒸気の温度は１８２℃、圧力は１．１ＭＰａであり、この蒸気を第二熱交換器（ｉ＝２）に導入した。第四晶析槽（ｉ＝４）で発生した蒸気の温度は１５６℃、圧力は０．６ＭＰａであり、この蒸気を第一熱交換器（ｉ＝１）に導入した。各熱交換器で熱交換した後の凝縮液は、それぞれ、温度が１００℃、圧力が０．１ＭＰａとなるように降圧した後、凝縮液回収槽に回収した。 The temperature of the steam generated in the first crystallization tank (i = 1) was 220 ° C. and the pressure was 2.3 MPa. This steam was introduced into the fourth heat exchanger (i = 4). The temperature of the steam generated in the second crystallization tank (i = 2) was 207 ° C. and the pressure was 1.8 MPa, and this steam was introduced into the third heat exchanger (i = 3). The temperature of the steam generated in the third crystallization tank (i = 3) was 182 ° C. and the pressure was 1.1 MPa, and this steam was introduced into the second heat exchanger (i = 2). The steam generated in the fourth crystallization tank (i = 4) had a temperature of 156 ° C. and a pressure of 0.6 MPa, and this steam was introduced into the first heat exchanger (i = 1). The condensate after heat exchange in each heat exchanger was reduced in pressure so that the temperature was 100 ° C. and the pressure was 0.1 MPa, respectively, and then recovered in the condensate recovery tank.
図１に示す４個の熱交換器と４個の晶析槽とを有する製造装置（ｎ＝４）を使用して、表２に示す条件で、ＣＴＡスラリーを加熱し、得られたＣＴＡ水溶液を水素添加処理し、得られたＣＴＡ処理液を降圧冷却した場合におけるエネルギー効率を比較例１と同様にエクセルギーロスで評価した。 The CTA aqueous solution obtained by heating the CTA slurry under the conditions shown in Table 2 using a production apparatus (n = 4) having four heat exchangers and four crystallization tanks shown in FIG. As in Comparative Example 1, the energy efficiency was evaluated by exergy loss when the obtained CTA treatment liquid was subjected to pressure reduction cooling.
各晶析槽で発生した蒸気の温度および圧力は比較例１と同一に設定した。第一晶析槽（ｉ＝１）で発生した蒸気を第四熱交換器（ｉ＝４）に導入した。熱交換後の凝縮液を第二晶析槽（ｉ＝２）で発生した蒸気の温度および圧力と等しくなるように降圧させた後、ここの蒸気に導入して高温流体を形成し、この高温流体を第三熱交換器（ｉ＝３）に導入した。この第三熱交換器で熱交換した後の凝縮液を第三晶析槽（ｉ＝３）で発生した蒸気の温度および圧力と等しくなるように降圧させた後、この蒸気に導入して高温流体を形成し、この高温流体を第二熱交換器（ｉ＝２）に導入した。さらに、第二熱交換器で熱交換した後の凝縮液を第四晶析槽（ｉ＝４）で発生した蒸気の温度および圧力と等しくなるように降圧させた後、この蒸気に導入して高温流体を形成し、この高温流体を第一熱交換器（ｉ＝１）に導入した。その後、第一熱交換器で生成した凝縮液は、温度が１００℃、圧力が０．１ＭＰａとなるように降圧した後、凝縮液回収槽に回収した。 The temperature and pressure of the steam generated in each crystallization tank were set to be the same as in Comparative Example 1. The steam generated in the first crystallization tank (i = 1) was introduced into the fourth heat exchanger (i = 4). The condensate after heat exchange is depressurized so as to be equal to the temperature and pressure of the steam generated in the second crystallization tank (i = 2), and then introduced into this steam to form a high-temperature fluid. The fluid was introduced into the third heat exchanger (i = 3). The condensate after the heat exchange in the third heat exchanger is depressurized so as to be equal to the temperature and pressure of the steam generated in the third crystallization tank (i = 3), and then introduced into the steam to increase the temperature. A fluid was formed and this hot fluid was introduced into the second heat exchanger (i = 2). Furthermore, after reducing the pressure of the condensate after the heat exchange in the second heat exchanger to be equal to the temperature and pressure of the steam generated in the fourth crystallization tank (i = 4), A hot fluid was formed and this hot fluid was introduced into the first heat exchanger (i = 1). Thereafter, the condensate produced in the first heat exchanger was depressurized so that the temperature became 100 ° C. and the pressure became 0.1 MPa, and then collected in the condensate collection tank.
表１および表２のエクセルギーロスを比較すると、本発明の製造方法では、従来の製造方法に比べて、エクセルギーロスを６２．１％低減できた。 Comparing the exergy loss of Table 1 and Table 2, the production method of the present invention was able to reduce the exergy loss by 62.1% compared to the conventional production method.
１ 混合槽
２１ 第一熱交換器（ｉ＝１）
２２ 第二熱交換器（ｉ＝２）
２３ 第三熱交換器（ｉ＝３）
２４ 第四熱交換器（ｉ＝４）
３ 熱交換器
４ 水素添加反応槽
５１ 第一晶析槽（ｉ＝１）
５２ 第二晶析槽（ｉ＝２）
５３ 第三晶析槽（ｉ＝３）
５４ 第四晶析槽（ｉ＝４）
６ 固液分離装置
７１〜７４ 圧力調整弁
８ 凝縮液回収槽
９ 蒸気配管
１０ 凝縮液配管
ＣＴＡ 粗テレフタル酸
ＰＴＡ 高純度テレフタル酸
1 Mixing
22 Second heat exchanger (i = 2)
23 Third heat exchanger (i = 3)
24 Fourth heat exchanger (i = 4)
3
52 Second crystallization tank (i = 2)
53 Third crystallization tank (i = 3)
54 Fourth crystallization tank (i = 4)
6 Solid-
Claims (5)
レフタル酸スラリーを形成する工程、（II）該粗テレフタル酸スラリーを複数の熱交換器で段階的に加熱して溶解させ粗テレフタル酸水溶液を形成する工程、（III）該粗テレフ
タル酸水溶液を水素添加処理する工程、（IV）水素添加後のテレフタル酸水溶液を複数の晶析槽で段階的に降圧冷却してテレフタル酸を晶析させる工程、（V）得られたテレフタ
ル酸スラリーを固液分離する工程を含む高純度テレフタル酸の製造方法において、
前記工程（II）が、
工程（IV）において降圧冷却により発生する蒸気を熱交換器に導入して粗テレフタル酸スラリーを加熱する工程（II−Ａ）を少なくとも１つと、
工程（IV）において降圧冷却により発生する蒸気と、該蒸気より高温高圧の蒸気が導入された熱交換器で生成する凝縮液とを含む高温流体を該熱交換器よりも低温の熱交換器に導入して粗テレフタル酸スラリーを加熱する工程（II−Ｂ）を少なくとも１つ含む
ことを特徴とする高純度テレフタル酸の製造方法。 (I) A step of mixing crude terephthalic acid obtained by liquid phase oxidation of para-xylene and water to form a crude terephthalic acid slurry, and (II) heating the crude terephthalic acid slurry in stages with a plurality of heat exchangers. (III) Step of hydrogenating the crude terephthalic acid aqueous solution, (IV) Step-by-step cooling of the aqueous terephthalic acid solution after hydrogenation in multiple crystallization tanks In the method for producing high-purity terephthalic acid, including the step of crystallizing terephthalic acid, and (V) solid-liquid separation of the obtained terephthalic acid slurry,
The step (II)
At least one step (II-A) of heating the crude terephthalic acid slurry by introducing steam generated by pressure reduction cooling in the step (IV) into a heat exchanger;
In step (IV), a high-temperature fluid containing steam generated by step-down cooling and a condensate generated in a heat exchanger into which high-temperature and high-pressure steam is introduced is converted into a heat exchanger having a temperature lower than that of the heat exchanger. A method for producing high-purity terephthalic acid, comprising at least one step (II-B) of introducing and heating the crude terephthalic acid slurry.
前記工程（II）において、少なくとも、前記晶析槽で降圧冷却により発生する蒸気を加熱源とする熱交換器をｎ個（ただし、最も低温の熱交換器を熱交換器（１）とし、順に高温側に、熱交換器（２）、熱交換器（３）、・・・、熱交換器（ｎ−１）とし、最も高温の熱交換器を熱交換器（ｎ）とする）使用し、
熱交換器（ｎ）には、晶析槽（１）で降圧冷却により発生する蒸気が導入され、
熱交換器（ｉ）には、晶析槽（ｎ−ｉ＋１）で降圧冷却により発生する蒸気と熱交換器（ｉ＋１）で生成する凝縮液とを含む高温流体が導入される（ただし、ｉは１以上ｎ−１以下の整数である）
ことを特徴とする請求項４に記載の高純度テレフタル酸の製造方法。 In the step (IV), the number of crystallization tanks is n (where n is an integer of 2 or more, the crystallization tank having the highest temperature and pressure is the crystallization tank (1)), and the crystallization tank ( 2), the crystallization tank (3), ..., the crystallization tank (n-1), the lowest temperature and low pressure crystallization tank is the crystallization tank (n)),
In the step (II), at least n heat exchangers using steam generated by pressure reduction cooling in the crystallization tank as a heating source (however, the lowest temperature heat exchanger is the heat exchanger (1), and in order) On the high temperature side, use heat exchanger (2), heat exchanger (3), ..., heat exchanger (n-1), and use the hottest heat exchanger as heat exchanger (n). ,
In the heat exchanger (n), steam generated by pressure reduction cooling in the crystallization tank (1) is introduced,
The heat exchanger (i) is introduced with a high-temperature fluid containing steam generated by pressure reduction cooling in the crystallization tank (n−i + 1) and condensate generated in the heat exchanger (i + 1) (where i is (It is an integer from 1 to n-1)
The manufacturing method of the high purity terephthalic acid of Claim 4 characterized by the above-mentioned.
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