Determination of trace water in industrial butadiene. Karl Fischer coulometric method (2)

5 Apparatus and equipment

5.

5.

b) Sensitivity 0.

5.

5.

5.

5.

6 sampling

The cylinder (5.

Note: The cleaned steel cylinder can be placed in a blast drying oven towel at a temperature of 110°C, and nitrogen gas (4.

7 Preparation for analysis

7.

Note: An appropriate amount of ethylene glycol (such as 10% of the total volume) can be added to the anolyte to promote the absorption of trace water in the sample

7.

7.

7.

8 Measurement steps

8.

8.

Note: If the environmental temperature is lower than 25℃, the gasification effect of the sample will be affected.
At this time, the capillary tube can be immersed in a water bath of (25～35)℃
.

8.
1.
2 Open the gas outlet valve of the injection cylinder to allow the sample to flow out and vaporize.
Blow the injection system for at least 30 minutes.
Insert the capillary port at one end of the electrolytic cell into the bottom of the electrolytic cell.
After purging for 5 minutes, close the cylinder valve
.

8.
1.
3 Set the delay time of the moisture meter according to the sampling time.
After the moisture meter enters the measurement state, use an electronic balance (5.
2a) to accurately weigh the sample cylinder
.
Open the cylinder valve for sample injection, and control the injection volume according to Table 1.
After the sample is injected, close the cylinder valve and start the moisture meter for titration
.
After the completion of the sample injection, the sample cylinder is accurately weighed one after another, and the difference between the two weighings is the sample mass
.
After the titration is completed, record the measured moisture content
.

Table 1 Injection control requirements of capillary gasification method

8.
2 Flash vaporizer vaporization method

8.
2.
1 Assemble the sample cylinder (5.
5) and the flash evaporator (5.
6) according to the requirements of the instrument manual, connect the gas outlet of the flash evaporator and the titration cell of the Karl Fischer coulometer (5.
1) with a clean polyethylene tube, Insert the vinyl tube into the bottom of the titration cell
.
Set the vaporization temperature of the flash evaporator to 100℃, and the sampling speed to 2L/min
.

Note: The mass flow meters attached to the flash meter are calibrated and displayed based on xenon gas.
The volume setting involved in this section also refers to the apparent value based on ammonia gas
.

8.
2.
2 Open the gas outlet valve of the injection cylinder, make the sample flow through the flash evaporator, and use at least 30L of sample gas to purge the injection system
.

8.
2.
3 Set the injection volume of the flash meter according to Table 2 and set the delay time of the moisture meter.
After the moisture meter enters the measurement state, turn on the flash meter for sample injection, and start the moisture meter to perform titration after the sample is completed
.
After the titration is completed, record the measured moisture content
.

Table 2 Sampling control requirements of flash vaporizer gasification method

Related Links: Determination of Trace Water in Industrial Butadiene by Karl Fischer Coulometric Method (1)