阅读说明：本技术 甲醛浓缩装置以及甲醛浓缩的方法 (Formaldehyde concentrating device and formaldehyde concentrating method ) 是由 杨加义 赵立军 李军 王启 杨军 林晓燕 高勇 陈星� 洪吉俊 曹海金 于 2021-06-08 设计创作，主要内容包括：本发明涉及甲醛浓缩技术领域,公开了一种甲醛浓缩装置以及甲醛浓缩的方法。所述装置包括升膜式浓缩器,所述升膜式浓缩器包括换热器以及与所述换热器相连通设置的分离室,其中,所述换热器的底部设置有甲醛液进料口。使用该装置的甲醛浓缩方法能够将甲醛浓度提高至70％以上。(The invention relates to the technical field of formaldehyde concentration, and discloses a formaldehyde concentration device and a formaldehyde concentration method. The device comprises a climbing film concentrator, wherein the climbing film concentrator comprises a heat exchanger and a separation chamber communicated with the heat exchanger, and a formaldehyde liquid feeding port is formed in the bottom of the heat exchanger. The formaldehyde concentration method using the device can improve the formaldehyde concentration to more than 70%.)

1. The formaldehyde concentrating device is characterized by comprising a rising film concentrator, wherein the rising film concentrator comprises a heat exchanger (1) and a separation chamber (2) communicated with the heat exchanger (1), and a formaldehyde liquid feeding hole (4) is formed in the bottom of the heat exchanger (1).

2. The device according to claim 1, wherein the heat exchanger (1) further incorporates heat exchanger tubes (3) arranged in parallel;

preferably, the number of the rows of the heat exchanger tubes (3) is 400-600;

preferably, the length of the heat exchanger tube array (3) is 3800-.

3. The device according to claim 1 or 2, wherein the heat exchanger (1) further comprises a condensed water outlet (5) and a heating steam inlet (6);

preferably, the condensed water outlet (5) is arranged at a distance of 150-250mm from the bottom of the heat exchanger (1);

preferably, the heating steam inlet (6) is provided at 3500-4000mm from the bottom of the heat exchanger (1).

4. The device according to claim 1, wherein the separation chamber (2) is arranged at 4300-.

5. The device according to claim 1 or 4, wherein the separation chamber (2) comprises a concentrated formalin outlet (7) and a secondary steam outlet (8), wherein the formalin outlet (7) is arranged at the bottom of the separation chamber (2).

6. The device according to claim 5, wherein the secondary steam outlet (8) is arranged 0-300mm from the top of the separation chamber (2).

7. A method for concentrating formaldehyde, characterized in that the method is carried out in an apparatus according to any one of claims 1-6, wherein the method comprises:

(a) the formaldehyde solution enters the heat exchanger tube nest (3) from a formaldehyde solution feed inlet (4) at the bottom of the heat exchanger (1);

(b) the formaldehyde liquid is evaporated in a heat exchanger tube nest (3), and the generated steam enters a separation chamber (2) of the heat exchanger;

(c) the steam is subjected to negative pressure flash in a separation chamber (2) so that the steam is separated from the liquid.

8. The process of claim 7, wherein in step (a), the feed rate of the formaldehyde liquor is 7-13 t/h.

9. The method of claim 7, wherein in step (b), the conditions of evaporation comprise: the residence time of formaldehyde in the concentrator is controlled to be 1-2 min.

10. The method of claim 7, wherein in step (c), the conditions of the negative pressure flash evaporation comprise: the concentrator pressure was controlled at-89 kPa to-65 kPa.

Technical Field

The invention relates to a formaldehyde concentration technology, in particular to a formaldehyde concentration device and a formaldehyde concentration method.

Background

The disadvantages of the existing formaldehyde concentration system are as follows: the volume of the concentrator is large V equal to 30m³(ii) a The mass of the concentrator is large, and M is 20.47 t; the feeding load is low, and F is 8 t/h; in order to meet production requirements, a plurality of sets of parallel operation are required, the operation period is short, the operation is stopped for cleaning about 15(10-20) days, the labor intensity of personnel is high, and the continuity of the whole production is influenced; the feeding of the trioxymethylene reactor after technical transformation needs 70% concentration of formaldehyde as a material, but the concentration of formaldehyde in the feeding of the existing formaldehyde concentration system of the original device is 40%, the concentration of formaldehyde is improved to 60% by utilizing the partial pressure reduction principle of formaldehyde at low pressure, the concentration effect is not ideal, the concentration efficiency is low, and the concentration of formaldehyde after concentration can not meet the feeding requirement of the trioxymethylene reactor.

In conclusion, the existing concentrator is a gas-liquid separator, the structure is simple, the diameter of monomer equipment is large, in order to prevent concentrated formaldehyde from being pumped out from the top, a certain height is required for a concentrating device, the retention time of the formaldehyde in a concentrating system is long, the formaldehyde is easy to flash and generate small formaldehyde particles, periodic parking is needed for cyclic cleaning, the labor intensity of personnel is high, and the formaldehyde harms the physical and mental health of the personnel.

Therefore, the research and development of a formaldehyde concentrating device and a formaldehyde concentrating method are of great significance.

Disclosure of Invention

The invention aims to overcome the defects of a formaldehyde concentration system in the prior art, and provides a formaldehyde concentration device and a formaldehyde concentration method, wherein the formaldehyde concentration can be increased to more than 70%.

In order to achieve the above object, the first aspect of the present invention provides a formaldehyde concentrating apparatus, wherein the apparatus comprises an ascending membrane concentrator, the ascending membrane concentrator comprises a heat exchanger 1 and a separation chamber 2 communicated with the heat exchanger 1, and a formaldehyde liquid feed port 4 is arranged at the bottom of the heat exchanger 1.

In a second aspect, the present invention provides a process for the concentration of formaldehyde, wherein the process is carried out in an apparatus as described above, the process comprising:

(a) the formaldehyde solution enters a heat exchanger tube nest 3 from a formaldehyde solution feed inlet 4 at the bottom of the heat exchanger 1;

(b) the formaldehyde liquid is evaporated in a heat exchanger tube array 3, and the generated steam enters a separation chamber 2 of the heat exchanger;

(c) the vapor is flashed in the separation chamber 2 by negative pressure so that the vapor is separated from the liquid.

Through the technical scheme, the invention carries out technical transformation on the prior device of the polyformaldehyde (formaldehyde concentration system), optimizes the flow, and has the advantages that:

(1) the volume of the formaldehyde concentration device is small and is only 9-10% of the volume of the formaldehyde concentration device in the prior art;

(2) the mass of the formaldehyde concentration device is small, and is only 10-11% of that of the formaldehyde concentration device in the prior art;

(3) the formaldehyde liquid feed load is high, for example, up to F ═ 13 t/h;

(4) the running period is long: 60 days;

(5) high concentration efficiency, low investment and good concentration effect.

Drawings

FIG. 1 is a schematic view of a formaldehyde concentrating apparatus of the present invention.

Description of the reference numerals

1 heat exchanger 2 separation chamber 3 heat exchanger tube

4 a formaldehyde solution feed inlet 5, a condensed water outlet 6 and a heating steam inlet

7 formaldehyde liquid outlet 8 secondary steam outlet

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention provides a formaldehyde concentrating device, which comprises a rising film concentrator, wherein the rising film concentrator comprises a heat exchanger 1 and a separation chamber 2 communicated with the heat exchanger 1, and a formaldehyde liquid feeding hole 4 is formed in the bottom of the heat exchanger 1.

According to the invention, the climbing-film concentrator is additionally arranged on the basis of the original formaldehyde concentrating device, wherein the original formaldehyde concentrating device comprises a formaldehyde concentrator, a refined formaldehyde heater, a concentrated formaldehyde pump and a dilute formaldehyde condenser; specifically, the original formaldehyde concentration device comprises a secondary concentration preheater, a secondary concentration heater, a secondary concentrator, a secondary concentration delivery pump, a secondary concentration dilute aldehyde circulating pump, a secondary concentration condenser, a secondary concentration quencher and a secondary concentration cooler.

According to the invention, as shown in fig. 1, the heat exchanger 1 is also provided with heat exchanger tubes 3 arranged in parallel; wherein, the number of the parallel arranged rows of the heat exchanger tube array 3 is 400-600, preferably 460-500, and more preferably 47-480; in addition, the length of the heat exchanger tube array 3 is 3800-; so that the formaldehyde liquid is heated, boiled and quickly vaporized under the action of the heating steam after entering the heat exchanger tube nest 3, the formaldehyde steam quickly rises in the tube nest, and the formaldehyde liquid is driven by the high-speed rising steam to form a film-shaped rise along the tube wall and continuously evaporate. The invention can make the volume of the formaldehyde concentration device small, only 9-10% of the volume of the formaldehyde concentration system in the prior art, and the volume of the formaldehyde concentration system in the prior art is large, for example, up to V-30 m, under the limitation of the number of rows and the length of the heat exchanger tubes 3³。

In addition, it should be noted that the upper and lower portions of the heat exchanger tubes 3 in fig. 1 are communicated, and only the portion shown in fig. 1 is "broken".

In addition, the mass of the formaldehyde concentration device of the invention is small (light weight), which is only 10 to 11% of the mass of the formaldehyde concentration system in the prior art, while the mass of the formaldehyde concentration system in the prior art is large, for example, up to M ═ 20.47 t. In the present invention, the "mass of the formaldehyde concentrating apparatus" refers to the weight.

According to the invention, the heat exchanger 1 also comprises a condensed water outlet 5 and a heating steam inlet 6.

According to the invention, the condensed water outlet 5 is arranged at a distance of 150-250mm, preferably 180-220mm, more preferably 200-210mm from the bottom of the heat exchanger 1 so as to facilitate the outflow of the condensed water.

According to the invention, the heating steam inlet 6 is arranged at a distance of 3500-4000mm, preferably 3650-3850mm and more preferably 3700-3750mm from the bottom of the heat exchanger 1, so that the heating steam enters the heat exchanger tubes for vaporizing the formaldehyde liquid.

According to the invention, the separation chamber 2 is arranged at a distance of 4300-.

According to the invention, the separation chamber 2 comprises a concentrated formaldehyde liquid outlet 7 and a secondary steam outlet 8, wherein the formaldehyde liquid outlet 7 is arranged at the bottom of the separation chamber 2 so as to collect the concentrated formaldehyde liquid and facilitate the concentrated formaldehyde liquid to be conveyed to trioxymethylene for reaction by a concentrated formaldehyde conveying pump.

According to the invention, the secondary steam outlet 8 is arranged at a distance of 0-300mm, preferably 100-200mm from the top of the separation chamber 2, in order to facilitate the vapor-liquid separation and to lead out secondary steam.

In a second aspect, the present invention provides a method for concentrating formaldehyde, wherein the method is carried out in the apparatus described above, wherein the method comprises:

(a) the formaldehyde solution enters a heat exchanger tube nest 3 from a formaldehyde solution feed inlet 4 at the bottom of the heat exchanger 1;

(b) the formaldehyde liquid is evaporated in a heat exchanger tube array 3, and the generated steam enters a separation chamber 2 of the heat exchanger;

(c) the vapor is flashed in the separation chamber 2 by negative pressure so that the vapor is separated from the liquid.

According to the invention, in step (a), the feeding rate of the formaldehyde liquid is 7-13t/h, preferably 10-13t/h, the feeding load in the prior art is low, and only F is 8 t/h; in the present invention, at high feed, the yield can be increased.

According to the invention, in step (b), the formaldehyde solution is evaporated in the heat exchanger tubes 3, which evaporation is the first evaporation in the invention, wherein the evaporation conditions include: the residence time of formaldehyde in the concentrator is controlled to be 1-2min, preferably 1.5 min.

According to the invention, in step (c), the conditions of negative pressure comprise: the concentrator pressure is controlled at-89 kPa to-65 kPa, and in the present invention, the flash evaporation, which is the second evaporation, is performed by negative pressure.

According to the invention, the process of the invention also comprises a caustic washing step, wherein the conditions of the caustic washing operation comprise: the steam valve of the heat exchanger is closed, the vacuum of the separation chamber is broken, and the normal pressure is recovered. In addition, the alkali washing does not belong to daily operation, and can be carried out once every 60 days, so that the formaldehyde autopolymer of the system is clear, and the normal operation of the system is ensured.

According to the method, the retention time of high-concentration formaldehyde in the equipment is shortened, the long-period stable operation of monomer equipment is ensured, the labor intensity of personnel is reduced, and the harm of the formaldehyde to the health of staff is reduced.

The present invention will be described in detail below by way of examples.

Example 1

This example is intended to illustrate the process for concentrating formaldehyde using the apparatus of the present invention.

As shown in fig. 1:

the formaldehyde solution enters a heat exchanger tube array 3 from a formaldehyde solution feed inlet 4 at the bottom of a heat exchanger 1, wherein the feed rate of the formaldehyde solution is 10t/h, the number of the tube arrays 3 of the heat exchanger is 480, and the height of the tube arrays is 4000 mm; adding steam into the heat exchanger 1 from a heating steam inlet 6, wherein the heating steam inlet 6 is arranged at a position 3750mm away from the bottom of the heat exchanger 1, the temperature of the heating steam is 128 ℃, and the introduction amount of the heating steam is 2.5 t/h;

under the action of heating steam, formaldehyde liquid is heated to boil and is quickly vaporized, the formaldehyde steam quickly rises in the tubes, the formaldehyde liquid is driven by the high-speed rising steam to form a film-shaped rise along the tube wall, the retention time of the formaldehyde in the concentrator is controlled to be 1min, and condensed water flows out from a condensed water outlet 5 at the bottom of the heat exchanger 1, wherein the condensed water outlet 5 is arranged at a position 200mm away from the bottom of the heat exchanger 1;

the generated steam and the liquid phase jointly enter a separation chamber 2 of the heat exchanger, and the steam and the liquid are fully separated by negative pressure flash evaporation under the pressure of-70 kPa, wherein the separation chamber 2 is arranged 3200mm away from the bottom of the heat exchanger 1.

As a result, the vapor phase (secondary steam) was extracted by system vacuum through a secondary steam outlet 8 provided at a distance of 150mm from the top of the separation chamber 2; and 72 percent of the concentrated high-concentration formaldehyde is conveyed to trioxymethylene for reaction through a concentrated formaldehyde conveying pump through a formaldehyde liquid outlet 7; the operation period was set to 60 days, and the concentration ratio was set to 5.0.

Example 2

This example is intended to illustrate the process for concentrating formaldehyde using the apparatus of the present invention.

As shown in fig. 1:

the formaldehyde solution enters a heat exchanger tube array 3 from a formaldehyde solution feed inlet 4 at the bottom of the heat exchanger 1, wherein the feed rate of the formaldehyde solution is 7t/h, the number of the heat exchanger tube array 3 is 400, and the height is 3800 mm; adding steam into the heat exchanger 1 from a heating steam inlet 6, wherein the heating steam inlet 6 is arranged at a position 3500mm away from the bottom of the heat exchanger 1, the temperature of the heating steam is 128 ℃, and the introduction amount of the heating steam is 1.2 t/h;

under the action of heating steam, formaldehyde liquid is heated to boil and is quickly vaporized, the formaldehyde steam quickly rises in the tubes, the formaldehyde liquid is driven by the high-speed rising steam to form a film-shaped rise along the tube wall, the retention time of the formaldehyde in the concentrator is controlled to be 1 minute, and condensed water flows out from a condensed water outlet 5 at the bottom of the heat exchanger 1, wherein the condensed water outlet 5 is arranged at a position 150mm away from the bottom of the heat exchanger 1;

the generated steam and liquid phase jointly enter a separation chamber 2 of the heat exchanger, and the steam and the liquid are fully separated by negative pressure flash evaporation at the pressure of-89 kPa, wherein the separation chamber 2 is arranged at the position which is 4300mm away from the bottom of the heat exchanger 1.

As a result the vapour phase (secondary steam) is drawn off via system vacuum by a secondary steam outlet 8 located at a distance from the top of the separation chamber 2; 68% of the concentrated high-concentration formaldehyde is conveyed to trioxymethylene for reaction through a concentrated formaldehyde conveying pump through a formaldehyde liquid outlet 7; in addition, the operation period was designed to be 55 days, and the concentration ratio was 4.6.

Example 3

This example is intended to illustrate the process for concentrating formaldehyde using the apparatus of the present invention.

As shown in fig. 1:

the formaldehyde solution enters a heat exchanger tube array 3 from a formaldehyde solution feed inlet 4 at the bottom of the heat exchanger 1, wherein the feed rate of the formaldehyde solution is 13t/h, the number of the heat exchanger tube array 3 is 600, and the height is 4200 mm; adding steam into the heat exchanger 1 from a heating steam inlet 6, wherein the heating steam inlet 6 is arranged at a position 4000mm away from the bottom of the heat exchanger 1, the temperature of the heating steam is 130 ℃, and the introduction amount of the heating steam is 3.0 t/h;

under the action of heating steam, formaldehyde liquid is heated to boil and is quickly vaporized, the formaldehyde steam quickly rises in the tubes, the formaldehyde liquid is driven by the high-speed rising steam to form a film-shaped rise along the tube wall, the retention time of the formaldehyde in the concentrator is controlled to be 2 minutes, and condensed water flows out from a condensed water outlet 5 at the bottom of the heat exchanger 1, wherein the condensed water outlet 5 is arranged at a position 300mm away from the bottom of the heat exchanger 1;

the generated steam and the liquid phase jointly enter a separation chamber 2 of the heat exchanger, and the steam and the liquid are fully separated by negative pressure flash evaporation under the pressure of-65 kPa, wherein the separation chamber 2 is arranged at a position 4700mm away from the bottom of the heat exchanger 1.

As a result the vapour phase (secondary steam) is drawn off via system vacuum by a secondary steam outlet 8 located at a distance from the top of the separation chamber 2; and 70% of the concentrated high-concentration formaldehyde is conveyed to trioxymethylene for reaction through a concentrated formaldehyde conveying pump through a formaldehyde liquid outlet 7; the operation period was set to 60 days, and the concentration ratio was set to 4.8.

Comparative example 1

Existing formaldehyde concentration systems are used, i.e. the plant does not comprise an ascending membrane concentrator.

Specifically, the method comprises the following steps: formaldehyde concentrator, refined aldehyde heater, concentrated aldehyde pump, dilute aldehyde condenser.

As a result: the feeding load is low: f is 8 t/h; the operation cycle is short: the operation is carried out for about 15 days, the vehicle needs to be stopped for cleaning, the labor intensity of personnel is high, and the continuity of the whole production is influenced; and the concentration of the formaldehyde is increased to 60 percent, the concentration effect is not ideal, and the concentration of the concentrated formaldehyde can not meet the feeding requirement of the trioxymethylene reactor.

From the results of examples 1 to 3 and comparative example 1, it can be seen that: by adopting the formaldehyde concentration method, the formaldehyde concentration device provided by the invention is additionally provided with the climbing film concentrator, and the formaldehyde concentration is increased to 70% through negative pressure flash evaporation for trioxymethylene reaction.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.