Method for determining carbon tetrachloride of activated carbon
1 Scope
This standard specifies the determination of the adsorption rate (activity) of wood activated carbon carbon tetrachloride.
This standard applies to wood activated carbon.
2, activated carbon method summary
The carbon tetrachloride adsorption rate (activity) of activated carbon is determined by passing carbon tetrachloride-laden air through a sample of activated carbon of known quality under the specified conditions until the mass of the carbon sample is no longer increased, and then measuring the carbon sample. The quality of carbon tetrachloride. The test equipment required for this test consists mainly of a control system that supplies air pressure, a device that removes gaseous and liquid oil and water from the air, and a specific concentration of tetrachloride in the gas stream flowing through the activated carbon sample. The carbon preparation system and the control air mixture (air + quadruple carbon) are composed of a system of carbon sample flow rates.
3, the meaning and application of activated carbon
The activated carbon measured by this method is actually a measure of the pore volume of the activated carbon sample. This method is a means of determining the degree of activation of activated carbon. Therefore, it is also an effective method for quality control of gas phase activated carbon. This activity value is not necessarily a measure of the adsorption efficiency of the activated carbon for other adsorbates or the effectiveness of the other operating conditions.
4, activated carbon device
4.1 Rotameter, LZB-4.
4.2 adsorption tube (see Figure 1)
4.2.1 Perforated plate: The number of holes is 20-24, and the diameter of the hole is 0.3-0.4mm.
4.2.2 Adsorption tube: made of industrial white glass, the appearance requires no bubbles and other obvious problems. There should be no more welds and wrinkles in the glass weld, and the milled end of the pipe should be melted. The inner diameter of the tube inside the scale is in the range of (20?0.3)mm.
4.2.3 Grinding plug: no air leakage is allowed, and the density is good.
4.3 CTC vapor generation bottle (see Figure 2).
4.4 Pressure gauge: Model Y-60Z M10?1, accuracy 0.25, range 0-0.16Mpa.
4.5 Gas drying tower: 250mL.
4.6 porous gas washing bottle; 250mL.
4.7 constant temperature water bath.
5, installation
5.1 Install the components of the instrument as shown in Figure 3. Install the number of adsorption tubes as needed, but ensure that the flow distribution is even.
5.2 Process Description
Connect the instrument to the compressed air switch. After the compressed air is opened, the air first enters the air purifying bottle filled with activated carbon, and enters the buffer bottle through a dry bottle containing silica gel and a purification bottle containing molecular sieve, and then carbon tetrachloride vapor is generated. The bottle is then passed through a rotameter and a serpentine tube (wound with a proportional tube of 1 m or more) into the adsorption tube.
5.3 Airtight inspection
All components of the instrument and the installed instrument are inspected for air tightness before use. The steps are: a) the relationship cock K3; b) the compressed air is introduced to generate a pressure of 60 Kpa in the system; C) the piston K2 is closed, and the gas drop within 1 min is not more than 2.6 kPa. If it is unqualified, check the cause and repair or replace the non-hermetic parts.
6, activated carbon test conditions
6.1 Carbon layer height: (10?0.2) cm.
6.2 Gas flow rate: (1 670?70) mL/min.
6.3 Adsorption temperature: (25?1) °C
6.4 Carbon tetrachloride vapor: (250?10) mg/L.
7, activated carbon test procedures
7.1 Sample preparation
The sample is baked at 105-110 ° C to constant weight, placed in a desiccator for use. Wipe the adsorption tube and weigh it to m1 (along with the plug, accurate to 1mg). Divide the prepared sample two or three times. Installed into the adsorption tube, the carbon layer is high (10?2) cm (height after tapping). After filling, the tube plug is coated with Vaseline and then weighed to m 2 (accurate to 1 mg). Weighing is completed. Insert the adsorption tube vertically into the constant temperature water bath.
7.2 Carbon tetrachloride vapor generation bottle preparation
Carbon tetrachloride was added from the inlet tube to the carbon tetrachloride generation bottle, and the height of the carbonized carbon in the bottle was about 8 cm. Will GB/T12496.5 -1999
The carbon tetrachloride vapor generating bottle is connected to the system and placed vertically in an ice water bath (0-1 ° C).
7.3 Process operation
When everything is ready, open the cocks K1, K2, K3, k4, close K5, turn on the compressed air, let the clean and dry air pass through the CTC vapor generation bottle, adjust K1 until the total airflow is stable (1 670?70 )mL/min. After the parameters are stable, open K5, turn off K4, let the carbon tetrachloride-laden air pass through the adsorption tube, and press the stopwatch to ensure the airflow passes at a flow rate of (1 670?70) mL/min. Sample 1h. Then open K4 and close K5. Remove the adsorption tube and wipe the net and weigh m3 (accurate to 1mg). Put the adsorption tube into the device, open K5, close K4, and let the air flow pass through the sample for another 10 min. Repeat the above operation until the adsorption is saturated (the difference between the two weighings is not more than 10 mg). The compressed air is then turned off and the test is over.
8, the results of the description
8.1 Adsorption rate (activity) of granular activated carbon to carbon tetrachloride vapor is shown in formula (1):
M3— m2
A = ?100 ........................ (1)
M2—m1
Where: A----- carbon tetrachloride adsorption rate (activity), %;
M1---- the quality of the adsorption tube, g;
M2----the mass of carbon added to the adsorption tube before adsorption, g;
M3----The mass of carbon and carbon tetrachloride in the adsorption tube after adsorption, g.
8.2 The concentration of carbon tetrachloride vapor is shown in formula (2):
(m1—m2 )?106
C = ........................ (2)
Q?t
Where: C----- carbon tetrachloride vapor concentration, mg / L;
M3---- the mass after adsorption of the adsorption tube, g;
M2----the mass before adsorption of the adsorption tube, g;
Q----the gas flow rate during adsorption, Ml/min;
t---- adsorption time, min.
9, precision and deviation
The relative standard deviation of the results of two parallel samples shall not exceed 5%.
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