DD201507A1 - METHOD AND DEVICE FOR DETERMINING THE MASS FLOW OF FINE-CORROSIVE MATERIALS - Google Patents

Abstract

The invention relates to a method and apparatus for determining the mass flow feinkoerniger materials, especially when transporting dusty and feinkoerniger fuels and other substances used in metallurgical processes of any solids concentration and any operating pressures to the tuyeres of the blast furnace, for heating Siemens Martin furnaces, Kupferschachtoefen and similar metallurgical aggregates and metal casings for the purpose of refining, alloying, refining, and similar metallurgical processes. The aim is to achieve a continuous mass flow measurement process that provides quantitatively correct readings regardless of the technology used to deliver dust to the conveyor tube and at all dust concentrations and system pressures that are technically feasible. The inventive method including the device bypasses the complicated speed measurement in Zweiphasenstroemungen and has within the Foerderkanals no obstacle obstructing Meßfuehler. Fig. 1

Description

232490 4

Title of the invention

Method and device for determining the mass of fine-grained materials

Field of application of the invention

The invention relates to a method and a device for determining the Maaaenstromes fine-grained materials, especially when transporting powdery and fine-grained fuels in the supply to the tuyeres of the blast furnace for the partial replacement of lumpy coke in the production of pig iron. The method and apparatus can similarly be applied to the feeding of powdered or fine-grained fuels as additive in cupola furnaces, to heating Siemens-Martin ovens, copper-shaft furnaces and similar metallurgical aggregates, as well as to supplying dusty or fine-grained substances into metal baths for frying , Alloying, refining and similar metallurgical processes ·

Characteristic of the known technical solutions

Methods and devices outside the field of metallurgy for determining the mass flow for pulverulent and fine-grained goods, which are not particularly suitable for coal dust, are known, which do not provide exactly quantitative measured values, but only qualitative measuring signals or those only for pneumatic transport at very small plague

232490 4

material densities (£ _f2 <30 kg / nr) are suitable. The measuring methods and devices according to the patents DD - PS - 131 361 and DD - PS - 145 958 provide analog mass flow values that are reproducible only for a precisely defined density state and for a specific fuel dust quality and a tech-; These methods require calibration of the measuring methods with changes in the composition of the conveyed particles. Light-optical measuring methods according to patent DD-PS-142 606 are not suitable despite the variety of simultaneous data acquisition due to the lack of light transparency and reflection especially of the fuel dust in the case of two-phase currents. The measuring methods according to the patents DE-OS 2 554 565, DE - OS - 2 902 911 and DE - OS - 2 757 032 do not take into account the true state of the flowing in the measuring section dust-gas mixture, so that these measuring methods only approximated Can deliver measured values and are no longer applicable for high pesticide loadings (^ fp ^ O kg / nr).

Object of the invention

The aim of the invention is a mass flow measurement process which operates continuously for metallurgy and provides quantitatively correct measured values independently of the technology of the dust feed to the dust delivery tube and at all dust concentrations, especially in the dense phase, which are technically feasible.

Explanation of the essence of the invention

The invention is based on the object, a method including apparatus for determining the mass flow of fine-grained materials, especially in the transport of powdery and fine-grained fuels and other substances used in metallurgical processes of any pest-

232490 A

To develop fabric concentration and any operating pressures to the blast furnace, for heating Siemens stoves, copper shaft furnaces and similar metallurgical aggregates and in metal baths for the purpose of refining, alloying, refining and similar metallurgical processes, which bypasses the complicated speed measurement in two-phase flows and no flow obstructing For securing the conveying continuity and continuity, no conveying pipe constrictions or extensions should be present, and the method must operate without calibration of the measuring path and independent of the type of dust.

According to the invention the object is achieved in that the output of a bunker or a Dosiergefäßes for determining the initial density ^ _{fl of} a dust stream, which will be different depending on the technological need and flow properties of the goods, a Dichtemeßsonde ^ _{1 is} arranged. After this density measuring probe, a gas for reducing the dust flow density is added to the solids flow stream bumplessly over a special mixing apparatus. This lowered density <δ _f2 and the injected gas Vq (u) (relative to the standard state) are also measured with a density measuring probe ξ ^ p and measured with an orifice V _q / jt \. The bumpless mixing device has the same free flow cross-section as the delivery tube and contains a porous, gas-permeable, dust-blocking filter tube made of sintered metal or * resin bonded gravel «

It is also possible, in the case of several delivery pipes leaving a bunker or a dosing vessel, to determine the mass flow in each individual delivery pipe according to the stated method. Furthermore, one can determine the mass flow only in one or more at a plurality arranged delivery pipes according to the measuring method of the invention and from

232490 4

Analogy conclusions determine the total delivery rate in all delivery pipes ·

On the basis of these measured variables Vq (u)> 3 _f1 f 3 f 2 taking into account the gas quantity m _Q1 in the dust stream at the beginning of the measuring section and the gas quantity m * in * dust flow at the end of the measuring section, the mass flow can be determined by means of the simple balance approach :

^ώ Κ ⁺ »GT. ⁺ ^ G (N) '3 G (U) V ⁺ * ^G2

With the known dust grain density ^ _K and standard gas density and by measuring the dust flow temperatures T «, T" ^and pressures p-, p "before and after the mixing apparatus, the gas densities and volumes are converted into the operating state (Vq2» * gi »3g2 ^^ ^er M ⁹³⁸⁶¹¹ S ^ ¹¹⁰¹¹¹ ^ _K according to equation (2)

• jr - »no / Γ 7 \" ¹¹ I ^ ¹ I ". v2 ^

-1 · ^ S

'P _n T ₁ (2.1)

P T

⁽² · ³⁾

232490

At higher system pressures and higher pesticide concentrations in the dense-flow range, a simple temperature and pressure measurement suffices that the heat capacity of the solid, if any pesticide and gas have different temperatures, will prevail, neglecting the relaxation effects and thus

, P ₂ ,

The mass flow kv is thus simplified:

'G ₂ · --ϊ-2 ² . H ² . 1_G2_ (3)

G2 ^} ' ⁽ ff1

^P 2

These equations are evaluated by means of a microprocessor during the operating regime continuously after input of the measured quantities (T, p, V _{G (N)} , f _f1 , £ _f2 ) and pest values (f _K , ^ _{G (N)} ) »

To achieve a high measuring accuracy of the mass flow m, the injection gas quantity Vqyjjn, which depends on the magnitude of the system pressure ρ and the mass flow, must be selected so that up to ^ _f g values of P _{f 2} ** 0.6 · _s

232490

( q _g equal to density of debris) a density jump of ^ 100 kg / m ^ is achieved

Auaführungsbeispiel

The invention will be explained with reference to 3 Ausfüihrungsbeispielen · In the drawing show:

FIG. 1: Simplified block diagram of the mass flow measurement from a metering vessel at elevated system pressure.

2: Simplified block diagram of the mass flow measurement from a bunker ·

FIG. 3: Simplified block diagram of the mass flow measurement in the conveying tube to form a blast furnace wind ·

Embodiment 1

In the execution of the method according to FIG. 1, at an operating pressure P ₁ = 3.0 MPa, coal dust of a grain density q _K »1400 kg / nr is pneumatically fed by means of nitrogen of standard density ^ _G (y) = 1» 25 kg / d. m in a located in the conveyor pipe 3 mixing apparatus 5 injection gas 4 in the amount of V (j (jn ^a 250 m (u) / ^Q are conveyed ³ via a conveyor pipe 3 · For the purpose of determining the mass flow rate m ^ supplied to the dust flow, and the flow densities before and measured by the mixing apparatus 5 radiometrically with a size of 380 kg / m- ³ and _{f 2} ^s 280 kg / nr *

The temperatures before and after the mixing apparatus 5 are nearly equal and are T ^ T «« 353 K.

From the given equations (2), (2 * 1), (2.2) * (2.3)

23 2 49 0 4

follows from a process computer 2 a Maasenstrom of, 10 t / h · The length of the porous pipe section of the mixing apparatus 5 is at a clear tube width of 40 mm and at a flow rate of 5 cm / s about "1 = 500 mm ·

Embodiment 2:

In carrying out the method according to FIG. 2 0.15 MPa from a hopper 1 of coal dust of a grain density ^ ^ ^s 1400 kg / nr and an initial flow density $ f \ ^A 470 kg / m is pneumatically at a pressure of p .. β by means of air Immediately after the bunker outlet, injection gas 4 at 29 nr / _w / h is added to the dust stream via a mixing apparatus 5, so that the flow density is increased by a gas standard density ε (J (U) ^β 1) 293 kg / nr Q ^ ₀ is reduced to 280 kg / nr, and the pressure at the measuring point after the mixing apparatus p 'is 0.10 MPa. the temperature before and after the mixing apparatus 5 is equal and amounts to ₁ T ^ T "^ ι 313 K.

By means of a process computer 2, this results in evaluation of equations (2), (2 × 1), (2 × 2), (2 × 3), a mass flow of m _K = 10 t / h. The length of the porous pipe section of the mixing apparatus 5, assuming a clear pipe diameter of 40 mm and a flow rate of 5 cm / s 1 -β 750 mm,

Exemplary embodiment 3

In the embodiment of the method according to FIG. 3, at an overpressure of P ₁ »0.16 MPa, pulverized coal of a metering vessel 1 is pulverized with a grain density ρ _v » 1400 kg / nr and an initial flow density q _f1 β 420 kg / m Gas standard density Q _{1 Q} , ^ «1.25 kg / m ³ conveyed in delivery pipes, leading to the tuyeres of a blast furnace.

23 2 49 0 4

Immediately after the departure from the metering vessel 1 the dust flow of each conveyor pipe 3 via a mixing apparatus 5 injection gas 4 with V _G / w) a 2.5 nr / _N % / h is added, so that the

Flow density ß ^ «reduced to 300 kg / m · * and the pressure at the measuring point after the mixing apparatus 5 P ₂ = 0.10 MPa. The temperature before and after the mixer 5 is the same and is T ₁ ^ T ₂ ~ 313 K.

By means of a process computer 2, this results in evaluation of the equations (2), (2.1), (2.2) and (2.3) a mass flow of m _K = 0.4 t / h pipe. The length of the porous RöhrstUckes the mixing apparatus 5 is assuming a clear tube width of 10 mm and a flow rate of 8 cm / s 1 a 126 mm.

Claims (5)

23 2 49 0 4 9 Inventionaanapruoh 1 # Method for determining the mass flow of fine-grained materials, in particular for transporting powdery and fine-grained fuels and other substances of any concentration concentrated in metallurgical processes and any operating pressures to the blast furnace, for heating Siemen-Martin furnaces, copper furnaces and similar metallurgical aggregates and in metal baths for the purpose of Prischens, alloying, refining and similar metallurgical processes, characterized in that q to determine the important for process control Massenstromea only within a feed pipe (3) for reducing the flow density _f1 ^ _f2 an injection gas (4) smoothly over a Mixing apparatus (5) is fed and that the flow density f _f1 i, the system pressure ρ-, the temperature T ₁ immediately after a bunker (1) or · dosing (1), but before the mixing apparatus (5) and the flow density ξ _f2 * ^{the s} y ^{0i; em} "pressure P ₂ , the temperature Tp after the mixing apparatus (5) and measured together with the fixed values of the solid grain density ο _K , the gas standard density _{0 0} ( _Ν )» the measured value of the injection gas flow Vq / jjn (4) a process computer (2) are entered , the Maaaenatrom m _K according to the found formulas (2), (2.1), (2.2), (2.3) ¹ K ^{β V} G2 ~ Zr <U 2. The method according to item 1, characterized in that when conveying from a fluidizing metering vessel (1) with several parallel conveying pipes (3) the density ρ _f1 measured only in a conveying pipe (3) and this measured value for all other delivery pipes as P ^ is used for the mass flow determination. (2.1) 232490 U Ϊ2.H (2.3) determined. (2) 3. The method according to item 1, characterized in that in particular in the dense phase demand (£> £ ₂ > 160 kg / m) and / or at higher operating pressures (p ₂ > 0.6 MPa), the temperature difference T ₁ to Tg and the relaxation effect P ₁ to p _{2 are} negligible and the equations of calculation (3), (3.1), (3.2) G2 ^} (3) f1 ~ 9 f2 ⁾ v _G2 - v _{G (N)} . a. ! 2 ⁽³ · ²⁾ 232490 4 are used, wherein the measured values Tp, p ₂ »Vq2 * ^ G2 of the measuring points after the mixing apparatus (5) in the process computer (2) are entered. 4 · Apparatus for carrying out the method according to Pkt · 1 to 3, characterized in that the mixing apparatus (5) is equipped with a porous, gas-permeable, dust-blocking filter tube, which consists of sintered metal, wherein the inner diameter of the filter tube of the mixing apparatus (5) not expanded or narrowed, but equal to that of the delivery pipe (3) and the length of the filter tube is dimensioned so that the injection gas (4) diffusion-like, d. H. at a rate έ 10 cm / s into the dust flow. 5. Device according Pkt «4, characterized in that the porous, gas-permeable, dust-blocking filter tube of the mixing apparatus (5) consists of resin-bonded gravel. Dazu._JL ".Seiten drawings