Method and device for direct crystallization of polycondensate

A polycondensation and crystallization technology, applied in chemical instruments and methods, lighting and heating equipment, chemical/physical processes, etc., can solve problems such as limiting the scope of use, and achieve the effect of omitting the crystallization step

Pending Publication Date: 2020-05-15
POLYMETRIX AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since fluidized bed conditions are only achievable at high equipment and energy costs, the meaningful range of use of the method is limited for economical reasons

Method used

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  • Method and device for direct crystallization of polycondensate
  • Method and device for direct crystallization of polycondensate
  • Method and device for direct crystallization of polycondensate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0187] Process 10t / h of 2.5% initial crystallinity and T GR = PET pellets with an entry temperature of 140°C.

[0188] If 3000kg / h (X=0.3) with T Gas = Nitrogen at 220°C, then heat up to T PH = 171°C and the crystallinity increased to 32.5%, which corresponds to T KR = 18.7°C temperature increase due to crystallization. For heat of crystallization q, 115 J / g was used for 100% crystallinity, and for heat capacity c, 1.84 J / g / K was used.

[0189] T Gas Therefore than T GR +T KR 61.3°C higher, and X*(T Gas -T GR -T KR ) at 18.4°C, and T PH Than T GR +T KR 12.3°C higher.

[0190] The gas velocity at the gas outlet is 0.36 m / s, whereby fixed bed conditions exist. This results in a pressure drop of 34mbar. The residence time of the pellets in the treatment chamber was 16.3 minutes.

Embodiment 2

[0192] If the amount of gas in Example 1 is increased to 6000kg / h (X=0.6), then the temperature is raised to T PH = 181.2°C. Increased degree of crystallinity and thus T KR constant.

[0193] T Gas still better than T GR +T KR 61.3°C higher, and X*(T Gas -T GR -T KR ) is 36.8°C, and T PH Than T GR +T KR 24.2°C higher.

[0194] The gas velocity at the gas outlet is 0.73 m / s, whereby fixed bed conditions are still present throughout. This produces a pressure drop of 66mbar.

[0195] This example shows better heating at higher gas quantities in a fixed bed.

Embodiment 3

[0201] If the treatment chamber of Example 1 is divided into 4 zones 0.3 m high and the product is treated in each zone with a gas quantity of 6000 kg / h (X total = 2.4), the temperature is raised to T PH = 206°C.

[0202] at T KR In the case of constant, X*(T Gas -T GR -T KR ) is 166°C, T PH Than T GR +T KR 47.3°C higher.

[0203] The average gas velocity at the gas outlet was 0.79 m / s, whereby fixed bed conditions were always present. A pressure drop of 71 mbar results.

[0204] This example shows better heating in the multi-stage mode of operation.

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Abstract

The invention relates to a method for continuous production of a partly crystalline polycondensate pellet material. The method comprises the step of crystallizing the pellet material in a second treatment space (6a) under fixed bed conditions by supply of energy from the exterior by means of a process gas, wherein the process gas has a temperature (TGas), which is higher than the sum of the pellettemperature (TGR) and the temperature increase (TKR) which occurs due to heat of crystallization released in the second treatment space (6a), i.e., (TGas>(TGR+TKR)). The pellets at the exit from thesecond treatment space (6a) have an average temperature (TPH), which is 10 to 90 DEG C higher than the sum of the temperature of the pellets (TGR) and the temperature increase (TKR) which occurs due to heat of crystallization released in the second treatment space (6a), i.e., (TGR+TKR+90 DEG C)>=TPH>=(TGR+TKR+10 DEG C).

Description

technical field [0001] The present invention relates to a method and apparatus for the direct crystallization of polycondensates, especially polyesters such as polyethylene terephthalate (PET). Background technique [0002] The production of certain polymers, especially polycondensates such as polyesters, by melt polycondensation is generally not possible because of product degradation and unacceptable contamination by by-products due to the high thermal load associated therewith. For this reason, prepolymers with lower molecular weights are prepared by melt polycondensation. The prepolymer is then raised to the desired molecular weight in a solid-phase postcondensation (SSP, Festphasennachkondensation). This procedure is known from the prior art (eg Scheirs / Long (eds.), Modern Polyesters, Wiley 2003, Chapter 4, pp. 143ff.). [0003] For the SSP reaction, the prepolymer obtained by melt polycondensation is processed into pellets. To prevent the pellets from sticking toget...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B29B9/16C08G63/80C08G63/88C08G63/183B29K67/00
CPCB29B9/16C08G63/80C08G63/88C08G63/183B29B2009/165B29K2067/003F26B17/00C08G69/06C08J3/12B29B9/065B29B9/12B29B7/007B29B7/88B29B7/748B01J2/20B01J8/005B29C71/0009B29C71/0063C08J7/02B29C2035/1616
Inventor A·克里斯特尔M·穆勒
Owner POLYMETRIX AG
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