RU2502979C1 - Method to determine fluidity of powdered materials - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: method to determine fluidity of powdered materials consists in the fact that a hollow cylinder is installed so that its external diameter is inside the smallest circle of the tray, the weight is lifted to the upper position and fixed with a fixator, the hollow cylinder is filled with the help of a funnel, the volume of which is equal to the volume of the hollow cylinder, the weight is lowered and fixed in the lower position, the covers are closed with a gate, the fixator is pulled out, and the weight lifts the hollow cylinder upwards, and the powder is spilled onto the surface of the tray.

EFFECT: mechanised detection of fluidity of powdered materials with the purpose to exclude manual lifting of a cylinder and to determine regulated speed of its lifting.

1 dwg, 2 tbl

Description

The invention relates to the field of determining one of the main physicomechanical characteristics of powdered materials — fluidity, that is, the ability of a powder to flow through a given section per unit time under the influence of a driving force, the rationing of which is provided for by technical conditions, and can be applied in various industries involved in production and the use of powdered materials in technological processes. A known method for determining their fluidity using a funnel with a base diameter of 150 mm, a height of 250 mm and an exit diameter of 25 mm, equipped with a cork, providing a quick opening of the hole. 0.5 kg of powder is poured into the funnel, held for 5 seconds, then the hole opens and the stopwatch is turned on to fix the time of the rash. The determination is made five times and the average value of the expiration time is adopted, see Table 1 (No. 1, 2 TU 6-18-155-79, TU 6-18-139-7), or the amount of powder per unit time (No. 3, 4 TU 6-18-42-86, TU 6-46-016-92).

Table 1 No. p / p Extinguishing powder index Technical specifications Flow Requirement (T) one PF TU 6-18-155-79 no more than 50 s 2 PSB-3 TU 6-18-139-78 no more than 50 s 3 PGS-M TU 6-18-42-86 not less than 10 g / s four PGS-3 TU 6-46-016-92 not less than 10 g / s 5 Pirant - A TU 301-11-10-90 not less than 0.28 kg / s 6 PGHK "Veil" TU 84-07509103.452-96 not less than 0.28 kg / s

The fluidity of powders No. 5, 6 (TU 301-11-10-90 / GU 84-07509103.452-96) was determined in accordance with fire safety standards (NPB-170-98) by measuring the mass flow rate of the powder when it expired from the test device under working gas pressure. Load the test powder into the instrument. Then nitrogen or air is pumped to a pressure of 16 ± 0.5 atm. and the device is exposed to vibration, after which the powder is released for 6 seconds. and the valve is blocked. The fluidity of the powder T (kg / s) is determined by the mass difference of the test device at the beginning and end: dividing by the time of release -6 s.

The method for determining fluidity using a funnel (p. 1-4) has disadvantages: the difficulty of simultaneously opening the outlet and turning on the stopwatch, as well as the possibility of forming an arch and freezing of the powder, which will lead to an increased dispersion of parameters in time and, therefore, powder consumption.

The method for determining the fluidity of the powder upon expiration from the test device (p. 5, 6) is quite complicated in hardware design. In addition, a vibrostand, a cylinder with air (nitrogen), an injection line and a large powder flow rate for testing are required.

A known method for determining the fluidity according to the patent of the Russian Federation No. 2390756 IPC C01N 11/00 from 02.24.09, which consists in filling the test powder material of a cylinder mounted on a plate, slowly lifting it and fixing the diameter of the powder crumbled in a circle. The disadvantage of this method: manual lifting does not exclude the lifting of the cylinder with a deviation from the vertical axis, the lifting speed is not regulated. This may affect the measurement results. Patent No. 2390756 IPC C01N 11/00 of 02.24.09 was adopted as a prototype.

The results of determining the fluidity of potassium chloride powder with a specific surface of ~ 3000 cm ² / g and coarse powder with a specific surface of ~ 125 cm ² / g depending on the cylinder lifting speed are shown in Table 2.

table 2 Cylinder Lifting Time, s Flowability (diameter of powder dispersibility), mm Specific surface area 3000 cm ² / g, particle size 10 μm Specific surface 125 cm ^{2 /} g, particle size 240 microns 0.5 160 180 one 180 180 2 130 150 3 140 130 four 135 150 5 120 120 6 140 120

(10 см/с), где Н - высота цилиндра, равная 10 см, τ - оптимальное время подъема, равная 1 сек., что соответствует максимальной текучести (диаметру рассыпавшегося порошка).From the above data it follows that in order to exclude the influence of the cylinder walls on the outflow of the powder, the rate of its rise, which should be equal to $$\frac{N}{\tau }$$

(10 cm / s), where H is the height of the cylinder equal to 10 cm, τ is the optimal lifting time of 1 second, which corresponds to the maximum fluidity (diameter of the crumbling powder).

An object of the invention is the mechanization of determining the fluidity of powdered materials, with the aim of eliminating the manual lifting of the cylinder and establishing a regulated speed of its rise.

The technical result consists in the fact that to determine the fluidity of powdered materials, including filling a hollow cylinder with a powdery material and pouring the powder onto a pallet with flanging and marks on it in the form of circles with diameters from 100 mm to 200 mm from the center, every 10 mm and determining the fluidity the hollow cylinder is installed along the average diameter of the edge of the powder material scattered around the circle so that its outer diameter is inside the smallest circle of the pallet, the load is lifted to the upper position they are fixed with a lock, fill the hollow cylinder with a funnel, the volume of which is equal to the volume of the hollow cylinder, lower and fix the load in the lower position, close the casing with a shutter, pull out the lock and the load lifts the hollow cylinder up, and the powder spills over the surface of the pallet where it is placed seven concentric circles indicated in FIG.

The formula T _p = 1.94 T _in +136.56, where

T _p - fluidity (by dispersibility), mm

T _in - fluidity (after expiration through the funnel), g / sec.

The above formula allows you to determine the expected fluidity of powdered materials obtained by the method of flowing through a funnel by measuring the fluidity (dispersibility) of the proposed method.

.Thus, the fluidity (after expiration through the funnel) can be determined by the formula: $$T_{\mathrm{at}}=\frac{T_R-\mathrm{one}36,56}{\mathrm{one},9\mathrm{four}},g/\mathrm{from}e\mathrm{to}.$$

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The essence of the method is presented as an example:

Example: determination of fluidity of a powdery material. To exclude dusting of the powdered material during the test and to load it, the cylinder is enclosed in a casing having an opening closed by a shutter.

The hollow cylinder is mounted on a pallet with a flare and marked on it in the form of circles with diameters from 100 mm to 200 mm, so that its outer diameter is inside the smallest circle of the pallet. Raise the load to the upper position and fix it in this position with a latch. The feed funnel is filled with the test powder material and through the opening in the casing is mounted on the hollow cylinder, then after emptying the funnel is removed. The load is lowered and fixed in the lower position, the casing is closed with a shutter, the latch is pulled out, the load lifts the hollow cylinder up and the powdery material crumbles over the surface of the pallet with flanging. The fluidity is determined by the average diameter of the edge, scattered in a circle of powdered material.

For each sample, three parallel determinations are made, from which the average result (mm) is derived.

The outflow through the funnel and the fluidity determined by the average diameter of the crumbled powder when it expires from the cylinder are shown in table 3.

Table 3 Name of indicator Powder Grades Coldic (Germany) Megavit (Italy) Powder (England) Bekcon (Russia) "Veil" (Russia) Flow through a funnel (outlet diameter 10 mm) g / s 31 1,5 5.7 0.6 37 The fluidity, determined by the average diameter of the crumbling powder when it flows out of the cylinder, mm > 200 130 190 110 > 200

From table 3 it follows that the fire extinguishing powder Coldic (Germany) and "Veil", (Russia) have the best results in fluidity after flowing through the funnel and from the cylinder.

According to table 3, the formula T _p = 1.94 T _in +136.56 is derived

T _p - fluidity (by dispersibility), mm

T _in - fluidity (after expiration through the funnel), g / sec.

Claims (1)

A method for determining the fluidity of powdered materials, including filling a hollow cylinder with powdery material and pouring the powder onto a pallet with flanging and marks on it in the form of circles with a diameter of 100 mm to 200 mm from the center, every 10 mm and determining the fluidity by the average diameter of the edge crumbled by a circle of powdery material, characterized in that the hollow cylinder is mounted so that its outer diameter is inside the smallest circle of the pallet, lift the load to the upper position and fix Ator, fill the hollow cylinder with a funnel, the volume of which is equal to the volume of the hollow cylinder, lower and fix the load in the lower position, close the casing with a shutter, pull out the lock and the load lifts the hollow cylinder up, and the powder spills over the surface of the pallet.