Determination of trace water in ethylene and propylene for industrial use (1)

1 Scope

1.

1.

2 Normative references

The clauses in the following documents have become clauses of this standard after being quoted in this standard

GB/T 2366-1986 Determination of water content in chemical products by gas chromatography

GB/T8170-1987 Numerical Rounding Rules

GB/T13289-1991 Industrial ethylene liquid and gas sampling method

GB/T13290-1991 Industrial Propylene and Butadiene Liquid Sampling Method

3 Karl Fischer Coulomb Method

3.

When the measured gas passes through the electrolytic cell of the Karl Fischer coulometric analyzer, the water in the gas and the iodine and sulfur dioxide in the Karl Fischer reagent will react in the presence of organic bases (such as pyridine) and methanol :

H ₂ O+I ₂ +SO ₂ +CH ₃ OH+3RN→(RNH)SO ₄ CH ₃ +2(RNH)I

The consumed iodine is electrolytically supplemented by the anolyte containing iodide ions:

2I ^- → the I ₂ + 2E

The amount of iodine required for the reaction is directly proportional to the amount of electricity passing through the electrolytic cell.

3.

3.

3.

a) The sensing capacity is 0.

b) Sensitivity 0.

3.

3.

3.

3.

3.

3.

a) Inner diameter (0.
25±0.
01)mm, length (2.
0±0.
1)m, used for propylene analysis;

b) Inner diameter (0.
15±0.
01)mm, length (3.
0±0.
1)m, used for ethylene analysis;

3.
3.
2 Micro syringe: 100uL;

3.
3.
3 Medical injection needle: No.
9;

3.
3.
4 Tighten the nut;

3.
3.
5 Stainless steel ferrule: the middle hole, the diameter of 1.
5mm;

3.
3.
6 Gasket: Silicone rubber;

3.
3.
7 Plastic septa: PTFE , with a hole in the middle, with a diameter of 1.
5mm;

3.
3.
8 Benzene-water balance solution: prepared according to 5.
2.
1 of GB/T2366-1986;

3.
3.
9 Karl Fischer Coulometric electrolyte (catholyte, anolyte);

3.
3.
10 Ethylene glycol: the mass fraction of water is not more than 0.
05%;

3.
3.
11 Nitrogen: The volume fraction is not less than 99.
999%, and the water content is not higher than 3mL/m ³
.

3.
4 Sampling

Steel cylinders (3.
2.
5, 3.
2.
6) should be kept clean and dry before sampling
.
Collect liquid samples according to the technical requirements of GB/T13289-1991 and GB/T13290-1991
.

Note: The cleaned and dried cylinders can be placed in a blast drying box at a temperature of 110°C, and nitrogen gas (3.
3.
11) for 30 minutes to obtain a better drying effect
.

Related Links: Electrochemical Method for Determination of Trace Oxygen in Industrial Ethylene and Propylene (3)