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Summary of membrane distillation formaldehyde experiment


Release time:

2024-03-04

Summary of membrane distillation formaldehyde experiment

 

一、Membrane distillation flow chart and related design parameters

Design Parameters:

PTFE heating rod: 2.0KW, 220V

Magnetic pump: 0.25KW, 220V

Membrane area: 0.7 m 2

Design water inlet flow: 400L/h, design maximum water inlet flow: 600L/h

Film feeding temperature: 60-80℃

Film inlet pressure: normal pressure

Vacuum degree: -85~ -96kPa


二、Experimental data collection

Time

Sample name

Weight (Kg)

Formaldehyde (wt%)

TOX(wt%)

Methanol (wt%)

Remark

2023.1.5

Original solution

——

11

——

——

The original is C321 bottom dilute formaldehyde

Concentrate

——

27.63

——

——

Distillate

——

3.56

——

——

2023.1.31

Original solution

12

32.43

2.71

——

The original product is diluted with C332 production fluid.

Concentrate

8.9

40.54

0.8

——

Distillate

3.1

5.67

6.01

——

2023.2.1

Original solution

12.1

34

0.0185

0.45

As is SP3101 concentrated formaldehyde dilution

Concentrate

6.7

44

0.0044

0.46

Distillate

5.4

4.81

0.0637

0.55

2023.2.20

Original solution

15.7

7.36

8.35

1.91

The original solution is diluted from V453 mother solution

Concentrate

11.7

10.18

3.44

2.32

Distillate

4

2.58

6.01

6.53

2023.2.20

Original solution

11.7

10.18

3.44

2.32

The original solution is the concentrated solution in the previous column

Concentrate

8.9

12.8

1.14

1.49

Distillate

2.8

2.5

7.08

4.21

三、The data shows

1、Judging from the analytical data and theoretical calculations, the analytical data errors are large and the quality cannot be considered balanced.

2、 During evaporation, the temperature of the original water tank is generally around 70°C, the vacuum side pressure is generally between 0-5KPa (A), the cooling water volume is generally between 250-350L/h, and the temperature difference between the inlet and outlet of the cooling water is generally around 2°C. Through timing and weighing calculations and cooling water heat conversion, the evaporation capacity is approximately 2Kg/h.

3、When formaldehyde is concentrated alone, the formaldehyde concentration in the distillate is generally around 4%.

4、the stock solution containing paraformaldehyde is evaporated. From the analysis data, parformaldehyde easily passes through the distillation membrane during evaporation, and the formaldehyde concentration in the distillate is about 2.5%.

5、Taken together, have any one questions. That is, under ordinary evaporation without a distillation membrane at 0-5KPa (A), will the formaldehyde concentration of the distillate still be very low?

6、According to a set of equipment to process 7t/h dilute formaldehyde with a formaldehyde concentration of 10%, if the formaldehyde with a concentration of 38% is about 1.2t/h, and the dilute formaldehyde with a concentration of 4% is about 5.8t, according to the experimental data, every 0.7m² If the membrane evaporation capacity is 2Kg/h, the membrane area required is approximately 2030㎡.