Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/42—Separation; Purification; Stabilisation; Use of additives
  • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation

Definitions

• the present invention relates to a method for separating and filtering CTA in the preparation of purified terephthalic acid and a system for carrying out the same.
• the traditional CTA separation and filtration method is a rotary vacuum filter (RVF) device.
• the rotary vacuum filter has a large filtration area, and the system consumes a large amount of electricity.
• the temperature of the filter feed slurry must be 88 to 90 °C to meet the RVF operation.
• the third stage of crystallization needs to be equipped with a vacuum system. In order to cool the slurry to the required temperature, a large amount of cooling water is consumed, and the RVF has no functional zone division.
• the filtered mother liquor, the rinsing liquid and the dehumidification gas are all drawn through the same central tube to form
• the mixed liquid causes the rinsing liquid and the dehumidifying gas separating liquid which are less than impurities to be reused, and is mixed into the filtering mother liquid which requires impurity removal, and the formed mixed liquid is sent to the impurity removing device for impurity removal, thereby increasing the removal.
• the impurity removal and impurity removal load of the miscellaneous equipment increases the processing cost of the impurity removal.
• the present invention provides a method for separating and filtering CTA in the preparation of refined terephthalic acid and a system for realizing the same, and the method and the system can greatly reduce energy consumption and water consumption. And reducing the throughput of the impurity removal process.
• a method for separating and filtering CTA in the preparation of refined terephthalic acid which feeds the CTA slurry into a rotary pressure filter for solid-liquid separation to obtain a wet cake, a filter mother liquor, a rinse liquid and a dehumidification gas, Part of the filter mother liquor is used for impurity removal, and other filter mother liquors are recycled.
• the proportion of the filter mother liquor to be subjected to the impurity removal treatment should generally ensure that the level of impurities in the system meets the process requirements.
• the ratio of the filtration mother liquor to be removed may be usually 8 to 10% of the total amount of the filtration mother liquor.
• the whole filter mother liquid Before the filtration mother liquid is removed, the whole filter mother liquid should be subjected to gas-liquid separation to separate the gas therein, and the rinse liquid and the dehumidification gas should also be separately subjected to gas-liquid separation, and the wet cake can be separately Enter the drying unit for drying.
• the gas formed by gas-liquid separation of the filtration mother liquid, the rinsing liquid and the dehumidification gas may be subjected to centralized condensation treatment, and the gas obtained after condensation may be used as an inert gas required for the rotary pressure filter ( Usually used as a nitrogen gas cycle, the liquid obtained after condensation is recycled together with the filter mother liquid which is not subjected to impurity removal, and the liquid obtained by the corresponding gas-liquid separation of the rinse liquid and the dehumidification gas respectively is also not performed.
• the mixed filter mother liquor is recycled together.
• a system for separating and filtering CTA in the preparation of refined terephthalic acid comprising a rotary pressure filter, wherein the rotary pressure filter is provided with a CTA slurry inlet, a flushing liquid inlet, a nitrogen inlet, and a wet cake outlet, The mother liquor outlet, the rinse liquid outlet, and the dehumidification gas outlet are filtered, and the filtration mother liquid outlet is connected to the impurity removing device and the circulation tank which are juxtaposed to each other.
• the filter mother liquid outlet is connected to the impurity removing device and the circulation tank in a manner that the filter mother liquid outlet is connected to the filter mother liquid-liquid separation device through a pipeline, and the liquid outlet pipe of the filter mother liquid gas-liquid separation device is divided into two paths.
• the connecting device is connected all the way, and the other way is connected to the circulating groove.
• the flushing liquid outlet may be connected to the flushing liquid inlet of the flushing liquid gas-liquid separating device through a pipeline, and the dehumidifying gas outlet may be connected to the dehumidifying gas gas-liquid separating device through a pipeline
• the dehumidification gas inlet, the wet cake outlet can be connected to the wet cake drying device by a conveying device.
• the gas outlet of the filtered mother liquor gas-liquid separation device, the gas outlet of the flushing liquid gas-liquid separating device, and the gas outlet of the dehumidifying gas gas-liquid separating device may each be connected to a gas inlet of the gas condenser through a pipe,
• the gas outlet of the gas condenser may be connected to the gas inlet of the gas compressor through a pipe, the liquid outlet of the gas condenser may be connected to the circulation tank through a pipe, and the gas outlet of the gas compressor may be connected to the rotary type through a pipe
• the nitrogen inlet of the pressure filter, the liquid outlet of the flushing liquid-liquid separation device and the liquid outlet of the dehumidifying gas gas-liquid separating device may be connected to the circulation tank through pipes, respectively.
• the circulation tank can be connected to the oxidation reaction unit of the fine terephthalic acid preparation process through the pipeline to realize recycling.
• the beneficial effects of the invention are: separating the wet filter cake, the filter mother liquor, the rinsing liquid and the dehumidification gas separately by using the rotary pressure filter PF) instead of the conventional rotary vacuum filter (RVF) for separating the CTA. Since the impurities of the rinsing liquid and the dehumidifying gas are small, only the filtering mother liquid needs to be removed, and in the case that the impurity level in the system is ensured to meet the recycling process requirements, only a part of the filtering mother liquid is extracted for impurity removal.
• RPF can process higher temperature materials, thus reducing the degree of cooling of the pre-process, reducing the consumption of cooling water and the corresponding energy consumption, because the temperature of the discharged wet cake is higher, which reduces The amount of steam consumed by the wet cake drying reduces the corresponding energy consumption.
• Figure 1 is a schematic flow chart of the present invention.
• the present invention uses a rotary pressure filter (RPF) for the filtration of crude terephthalic acid (CTA), which typically includes a liquid filtration zone, an acid rinse zone, and a nitrogen purge.
• RPF rotary pressure filter
• CTA crude terephthalic acid
• CTA crude terephthalic acid
• the liquid filtration zone is provided with a filter mother liquor outlet
• the acid flushing zone is provided with a flushing liquid outlet
• the nitrogen dehumidifying zone is usually provided with a dehumidifying gas outlet, thereby realizing the separation of the wet filter cake, the filtering mother liquor, the washing liquid and the dehumidifying gas.
• the filtration mother liquor outlet is generally connected to the separation material inlet of the mother liquor gas-liquid separation device 2 through a pipe connection, and the rinse liquid outlet is usually connected to the rinse liquid inlet of the flushing liquid gas-liquid separation device 3 through a pipe, and the dehumidification gas outlet is usually passed through
• the pipe is connected to the dehumidification gas inlet of the dehumidification gas-liquid separation device 4, and the wet cake outlet of the RPF is usually connected to the drying device 10 by a conveying mechanism.
• the filter mother liquor gas-liquid separation device is generally provided with a gas outlet and a liquid outlet, and the flushing liquid gas-liquid separation device is usually provided with a gas outlet and a liquid outlet, the dehumidification gas
• the body gas liquid separation device is usually provided with a gas outlet and a liquid outlet.
• the liquid outlet of the filter mother liquor gas-liquid separation device can be divided into two paths by a liquid branching assembly 8 provided with two outlets, one of which is connected to the decontamination device 9 through a pipe, and the other outlet is connected to the circulation tank 7 through a pipe. .
• the liquid diverting assembly can employ a flow proportional adjustment valve or other existing flow dividing device.
• the liquid outlet of the flushing liquid-gas separation device and the liquid outlet of the dehumidifying gas gas-liquid separating device are usually connected to the circulation tank 7 through a pipe, respectively, and are recycled after being mixed with the filter mother liquid which is not subjected to impurity removal.
• the filtered mother liquor is subjected to gas-liquid separation before removing impurities to remove the gas.
• the filter mother liquor flowing out of the RPF usually first enters the gas-liquid separation device for filtering the mother liquor, and the filter mother liquor separating the gas generally does not need to enter the impurity removal device at all, and in the case that the impurity level in the system meets the system requirements, only The filtration mother liquor after partial gas-liquid separation is decontaminated.
• the filtration mother liquor to be removed may be usually 8 to 10% of the total amount of the filtration mother liquor, and the filtration mother liquor which is not involved in the impurity removal is usually fed into the circulation tank for recycling.
• the rinsing liquid and the dehumidifying gas are separated by gas-liquid separation and then sent to the circulation tank in the same manner as the filtration mother liquid which does not participate in the decontamination for recycling.
• the gas outlet of the filter mother liquor gas-liquid separation device, the gas outlet of the gas-liquid separation device of the rinse liquid, and the gas outlet of the dehumidification gas gas-liquid separation device are usually connected to the gas condenser 5 through a pipeline, respectively.
• the three pipes are first collected in one main pipe and then connected to the gas condenser 5.
• the gas condenser is usually provided with a gas (N 2 ) outlet and a liquid (acetic acid) outlet, which is usually connected to a gas compressor 6 through a pipe, which is usually connected to the circulation tank 7 through a pipe.
• the gas compressor is typically connected to the nitrogen feed ⁇ of the nitrogen dehumidification zone of the RPF through a pipe.
• ⁇ Separation and filtration by RPF consumes a large amount of ⁇ 2 . Therefore, the gas separated and separated from each gas and liquid needs to be separated by gas using a condenser to condense and separate the acetic acid gas. Normally, cooling water is supplied to the condenser to condense the acetic acid gas.
• the mixed gas After the mixed gas is sent to the condenser, it is condensed, and the gas discharged from the condenser (usually ⁇ 2 ) enters the gas compressor.
• the compressor is boosted by 1 to 1.5 bar, and the gas pressure is adjusted to the required value. Re-enter the gas inlet in the nitrogen dehumidification zone of the RPF for recycling.
• the acid (usually acetic acid) from the condenser will enter the circulation tank along the pipeline for recycling.
• the recycle tank is typically connected to the liquid feed inlet of the oxidation reaction unit via a conduit.
• the following process parameters can usually be used: CTA slurry entering the rotary pressure filter Around 118 °C, the acid is about 115 °C, N 2 70 °C, the wet cake discharged from the rotary pressure filter is about 115 °C, the mother liquor is about 118 °C, and the rinse is about 115 °C.
• the pre-staged three-stage crystallization cooling water consumption is reduced by about 40%, and the three-stage crystallization vacuum system and its required utility consumption (such as steam amount) can be omitted. And the amount of cooling water), reducing the area of the three-stage crystal condenser by about 50%.
• the wet cake discharged from the RPF enters a drying device for drying, and the temperature of the wet cake is about 25 ° C higher than the temperature of the wet cake discharged by the conventional process (the wet cake temperature discharged by the RVF is about 90 ° C, thereby The amount of steam in the subsequent drying process is reduced.

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• Oil, Petroleum & Natural Gas (AREA)
• Crystallography & Structural Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2009
  • 2009-08-13 CN CN2009100905099A patent/CN101624342B/zh active Active
  • 2009-12-07 IN IN1279DEN2012 patent/IN2012DN01279A/en unknown
  • 2009-12-07 WO PCT/CN2009/075363 patent/WO2011017870A1/zh active Application Filing
  • 2009-12-07 RU RU2012105734/04A patent/RU2505525C2/ru active

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