CN102980843A

CN102980843A - Method for detecting coke air hole characteristics

Info

Publication number: CN102980843A
Application number: CN201210567997XA
Authority: CN
Inventors: 国宏伟; 苏步新; 张建良; 任山; 邢相栋; 王春龙; 卢伟佳; 曹维超; 白亚楠; 李新宇
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2012-12-24
Filing date: 2012-12-24
Publication date: 2013-03-20

Abstract

The invention provides a method for detecting coke air hole characteristics. The method comprises the following step of: measuring the total volume of air holes contained in coke samples per unit mass by utilizing an automatic nitrogen absorption instrument, and then combining with real coke sample volumes, thereby obtaining the air hole rate of the coke samples. Capillary condensation phenomenon and volume equivalent exchange principle are utilized for determining pore diameter distribution by a gas absorption method, namely, liquid nitrogen amount filled in tested holes are equivalent to the volumes of holes. The method for detecting coke air hole characteristics provided by the invention is convenient to operate, is small in device volume, and has good repeatability.

Description

A kind of detection method of coke-blowhole feature

Technical field

The invention belongs to the iron-smelting raw material detection field, particularly a kind of detection method of coke-blowhole feature is applicable to the detection of STRENGTH ON COKE stomata characteristics.

Background technology

Coke is the important source material of blast furnace ironmaking, the stomata characteristics of coke be determine coke property principal element it

The coke-blowhole feature mainly comprises the porosity and gas cell distribution etc.The detection method of coke-blowhole feature has the national standard determination method, three kinds of image analyzer determination method and scanning microscopies at present.

National standard determination method: GB/T 4511.1-2008 " coke true relative density, false appearance are to the assay method of density and the porosity ", the coke specimen amount that the method needs is more, and automaticity is not high, and the error that human factor causes in the operating process is larger.The image analyzer determination method: the method is analyzed the picture gray scale and is judged pore by the intercepting picture, utilizes the area of pore recently to simulate the pore volume ratio and calculates the porosity, and the method needs expensive special image analyser.Scanning microscopy: the method obtains the each point reflectivity data by scanning, recently simulate the pore volume ratio by the line segment of the hole diameter that obtains, thereby obtain the porosity, but the method is utilized line segment recently to simulate the pore volume ratio to have certain defect.For the defective in the method, CN101135632 discloses a kind of determinator and assay method of charred coal porosity, scans whole coke mating plates and obtains several pictures, and picture is carried out statistical study, calculates the porosity.The method need to be made the coke mating plate, and equipment is huge, complicated operation.

More than in three kinds of methods National Standard Method can not obtain the gas cell distribution situation, though rear two kinds of methods can obtain gas cell distribution, but rear two kinds of methods need to be made the coke section, in more in the manufacturing process, little pore is destroyed, and because the pore that detects is some special tests plane, so it is not strong to detect coke-blowhole feature representativeness.And the sample of gas adsorption method detection coke-blowhole does not require section, and it is destroyed that pore does not have, so n2 absorption apparatus detection coke-blowhole characteristic is more accurate.

Summary of the invention:

The present invention designs a kind of method of energy accurate analysis coke-blowhole feature in order to overcome the deficiency of art methods, and can obtain charred coal porosity and gas cell distribution situation by test and computational analysis.A kind of detection method of coke-blowhole feature, based on gas adsorption method, utilize the automatic nitrogen adsorption instrument to detect the cumulative volume (ml/g) of contained pore in coke-blowhole pore size distribution situation and the unit mass coke sample, again in conjunction with coke sample true volume, thereby obtain the porosity of coke sample.The present invention can measure specific surface area, air vent aperture distribution situation and the pore cumulative volume of coke sample exactly, and can calculate the porosity of coke sample.Specific surface area is whether the sign coke-blowhole is flourishing, if pore is many, then corresponding specific surface area is large.Specific implementation process is as follows: the empty sample hose that (1) will be cleaned is contained in the degassed station of instrument, vacuum outgas 5 ± 1 minutes, and after the degassed end, the backfill helium unloads sample hose and covers immediately rubber stopper, weighs.The sample hose of (2) a certain amount of coke sample being packed into and having weighed is put into heat packs with sample hose, fixes with the METAL HEATING PROCESS double team, and then sample hose is installed on the degassed exit.After all need degassed sample all to install to degassed exit, be warming up to 300 ℃, vacuum outgas is more than 4 hours.(3) turn off heat packs, lightly from sample hose to withdraw from the heat packs, sample hose is cooled to room temperature, at this moment in the sample hose by the backfill helium, take off from degassed station.(4) sample is packed into the pore analysis station of instrument is analyzed in the stomata characteristics of steady temperature-196 ℃ lower STRENGTH ON COKE sample, namely under-196 ℃, adsorbs by liquid nitrogen STRENGTH ON COKE sample.Under different pressure, the nitrogen amount of sample absorption is different, obtains the Isothermal Adsorption Characteristics curve of nitrogen, as shown in Figure 1.The pore of the material of measuring is different, and under the relevant pressure, the uptake of nitrogen is different, so the isothermal adsorption characteristics curve of every kind of material is different.Total pore volume is the nitrogen soakage summation in each pressure stage, and the stages adsorbance of each material is different, so total pore volume is different.

Under liquid nitrogen temperature, nitrogen depends on the relative pressure (P/P of nitrogen in the adsorbance of solid surface ₀), work as P/P ₀In the time of in 0.05～0.35 scope, adsorbance and (P/P ₀) meet BET equation, BET adsorption isotherm equation:

\frac{P / P_{0}}{V (1 - P / P_{0})} = \frac{C - 1}{V_{m} C} \times P / P_{0} + \frac{1}{V_{m} C} - - - (1)

In the formula: V gas absorption amount

V _mSingle molecular layer saturated absorption

P adsorbate pressure

P ₀The adsorbate saturated vapour pressure

The C constant

Obtain the mono layer adsorption amount, thereby calculate the specific surface area of sample.Order

Y = \frac{P / P_{0}}{V (1 - P / P_{0})},

X=P/P ₀、

A = \frac{C - 1}{V_{m} C},

B = \frac{1}{V_{m} C}

Will

To X=P/P ₀Mapping is a straight line, and 1/(intercept+slope)=V _m, substitution (1) formula is namely tried to achieve specific surface area.

Work as P/P ₀0.4 o'clock, owing to produce the capillary condensation phenomenon, namely nitrogen begins to condense in the granule interior pore, by experiment and theoretical analysis, can measure pore volume, gas cell distribution.By the Isothermal Adsorption Characteristics curve, the pore cumulative volume is normally got P/P ₀The cryolac number of nitrogen adsorption amount during for maximal value or 0.99 left and right sides.Under the mark condition after the 1mL nitrogen cohesion (supposition cohesion density is constant) volume be 0.001547mL, the nitrogen adsorption amount can obtain the pore cumulative volume when multiply by on the Isothermal Adsorption Characteristics curve relative pressure P/P0 maximal value or 0.99 left and right sides.And calculate the true volume of coke sample by following formula, thereby obtain charred coal porosity.

In the formula: V _VeryBe coke specimen true volume, ml/g;

M is the coke specimen quality, g;

ρ _VeryBe coke specimen real density, g/ml.

In the formula: ε is the coke specimen porosity, %;

V _VeryBe coke specimen true volume, ml/g;

V _PoreBe unit coke specimen pore cumulative volume, ml/g.

The present invention can the Accurate Determining coke total pore volume and gas cell distribution, and can obtain charred coal porosity through calculating.What the gas adsorption method pore diameter distribution was measured utilization is capillary condensation phenomenon and volume equivalence exchange principle, and the amount of liquid nitrogen equivalence that is about to be full of in the measured hole is the volume in hole.Pore diameter distribution adopts BJH(Barrett-Joiner-Halenda usually) model.The present invention has easy to operate, and equipment volume is little, favorable repeatability.

Description of drawings:

Fig. 1 is the Isothermal Adsorption Characteristics curve map of nitrogen.

Embodiment

Adopt the present invention, measure the porosity and the gas cell distribution situation of the coke of three kinds of different manufacturers productions, measure simultaneously the porosity and the gas cell distribution situation of same coke with scanning microscopy.Wherein the automatic nitrogen adsorption instrument adopts the AUTOSORB-1-C-TCD of U.S. Kang Ta company.The implementation step is as follows:

Three kinds of each 200g of coke sample are got in distribution, put into drying box, dry 120min under 105 ℃ of temperature, and it is stand-by respectively to take by weighing after cooling 1～2g sample.

The empty sample hose that at first will clean is contained in the degassed station of instrument, vacuum outgas 5 ± 1 minutes, and after the degassed end, the backfill helium unloads sample hose and covers immediately rubber stopper, weighs.With the coke sample sample hose of packing into, sample hose is put into heat packs, fix with the METAL HEATING PROCESS double team, and then sample hose is installed on the degassed exit, be warming up to 300 ℃, vacuum outgas is more than 4 hours.Turn off heat packs, lightly from sample hose to withdraw from the heat packs, sample hose is cooled to room temperature, at this moment in the sample hose by the backfill helium, take off from degassed station.With the sample pore analysis station of packing into, under steady temperature-196 ℃, to adsorb by liquid nitrogen STRENGTH ON COKE sample, the stomata characteristics of STRENGTH ON COKE sample is analyzed.

The purity requirement of nitrogen and helium is more than 99.995% in the test.

Scanning microscopy is measured the porosity and the gas cell distribution of coke and is tested at this not in detailed introduction.

Table 1 is that method of the present invention and scanning microscopy draw the charred coal porosity contrast.Table 2 is that method of the present invention and scanning microscopy draw coke-blowhole distribution contrast.

Two kinds of distinct methods charred coal porosities of table 1 measurement result contrast (%)

Numbering	Method of the present invention	Scanning microscopy
			Coke
1	56.8	50.5
			Coke 2	67.6	55.7
Coke 3	58.1	51.2

Two kinds of distinct methods coke-blowholes of table 2 measure of spread result contrasts (%)

As can be seen from the above embodiments: use the inventive method can measure accurately the stomata characteristics of different coke, and the charred coal porosity measurement result is larger than scanning microscopy, this mainly is because scanning microscopy need to be made coke section, more in the manufacturing process in, little pore destroyed.And the sample of gas adsorption method detection coke-blowhole does not require section, and it is destroyed that pore does not have, and the method is more accurate at mesopore and micropore context of detection.

Claims

1. the detection method of a coke-blowhole feature, it is characterized in that: the method adopts gas adsorption method, utilize the cumulative volume of contained pore in the automatic nitrogen adsorption instrument measuring unit quality coke sample, again in conjunction with coke sample true volume, thereby obtain the porosity of coke sample.

2. the detection method of coke-blowhole feature according to claim 1 is characterized in that, the specific implementation process of this detection method is as follows:

The empty sample hose that (1) will clean is contained in the degassed station of automatic nitrogen adsorption instrument, vacuum outgas 5 ± 1 minutes, and after the degassed end, the backfill helium unloads sample hose and covers immediately rubber stopper, weighs;

The sample hose of (2) a certain amount of coke sample being packed into and having weighed is put into heat packs with sample hose, fixes with the METAL HEATING PROCESS double team, and then sample hose is installed on the degassed exit; After all need degassed sample all to install to degassed exit, be warming up to 300 ℃, vacuum outgas is more than 4 hours;

(3) turn off heat packs, lightly from sample hose to withdraw from the heat packs, sample hose is cooled to room temperature, at this moment in the sample hose by the backfill helium, take off from degassed station;

(4) sample is packed into the pore analysis station of automatic nitrogen adsorption instrument adsorbs by liquid nitrogen STRENGTH ON COKE sample under steady temperature-196 ℃, and the stomata characteristics of STRENGTH ON COKE sample is analyzed; Under different pressure, the nitrogen amount of sample absorption is different, obtains the Isothermal Adsorption Characteristics curve of nitrogen.

3. the detection method of coke-blowhole feature according to claim 2 is characterized in that, can obtain the pore cumulative volume by described Isothermal Adsorption Characteristics curve, and the pore cumulative volume is normally got P/P ₀The cryolac number of nitrogen adsorption amount during for maximal value or 0.99 left and right sides.

4. the detection method of coke-blowhole feature according to claim 3, it is characterized in that, suppose that cohesion density is constant, the rear volume of 1mL nitrogen cohesion is 0.001547mL under the mark condition, the nitrogen adsorption amount can obtain the pore cumulative volume when multiply by on the Isothermal Adsorption Characteristics curve relative pressure P/P0 maximal value or 0.99 left and right sides.

5. the detection method of coke-blowhole feature according to claim 1 is characterized in that, calculates the true volume of coke sample by formula (1), obtains charred coal porosity from formula (2) again:

In the formula: V _VeryBe coke specimen true volume, ml/g;

M is the coke specimen quality, g;

ρ _VeryBe coke specimen real density, g/ml;

In the formula: ε is the coke specimen porosity, %;

V _VeryBe coke specimen true volume, ml/g;

V _PoreBe the cumulative volume of unit coke specimen pore, ml/g.

6. the detection method of coke-blowhole feature according to claim 2 is characterized in that, the purity requirement of nitrogen and helium is more than 99.995% in the testing process.