DD201507B1 - METHOD FOR DETERMINING THE MASS FLOW OF FINE-COATED MATERIALS - Google Patents

Description

Fields of application of the invention

The invention relates to a method for determining the mass flow of fine-grained materials, in particular 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 process can similarly be applied to the feeding of powdered or fine-grained fuels as an additive in cupola furnaces, to the heating of Siemens-Martin furnaces, copper-shaft furnaces and similar metallurgical aggregates and to the feeding of pulverulent or fine-grained substances into metal baths for the purpose of refining, alloying, Refining and similar metallurgical processes.

Characteristic of the known technical solutions

Are known methods and devices outside the field of metallurgy for the determination of the mass flow for dusty and fine-grained goods, which are not particularly suitable for carbon dust, ie not exactly quantitative readings, but only provide qualitative measurement signals or only for the pneumatic transport at very small Solid densities (p _f2 <30 kg / m ³ ) are suitable. The measuring methods and devices according to the patents DD-PS 131361 and DD-PS 145958 provide analog mass flow values that are reproducible only for a precisely defined density state and for a specific fuel dust quality and have technically sufficient accuracy. These methods require calibration of the measuring methods with changes in the composition of the conveyed fine material. Light-optical measuring methods according to patent DD-PS 142606 are not suitable despite the variety of simultaneous data acquisition because of the lack of light transparency and reflection especially of the fuel dusts in dense two-phase flows. The measuring methods according to the patents DE-OS 2554565, DE-OS 2902911 and DE-OS 2757032 do not take into account the true state of the flowing in the measuring section dust-gas mixture, so that these measuring methods can provide only approximate measurements and for high solids loadings (p _f2 a 50kg / m ³ ) are no longer applicable.

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.

Presentation of the essence The invention is based on the object, a method for determining the mass flow of fine-grained materials,

In particular, when transporting pulverulent and fine-grained fuels and other substances used in metallurgical process of any solids concentration and any operating pressures to the tuyeres of the blast furnace, the

Heating of Siemens Martin furnaces, copper shaft furnaces and similar metallurgical aggregates and in metal baths To develop the purposes of refining, alloying, refining and similar metallurgical processes, the complicated Speed measurement in two-phase flows bypasses and no flow-restrictive sensors within the Must have delivery channel. To ensure the continuity of funding and continuity should no Förderrohrverengungen or

-erweitnngen be present, and the process must be without calibration of the test section and regardless of the Staubartarbeiten.

According to the invention the object is achieved in that the output of a bunker or a dosing to determine the Initial density Of _{1 of} a dust stream, depending on the technological need and flow characteristics of the material

will be different, a Dichtemeßsonde Of _{1 is} arranged. After this density measuring probe, a gas is added to the solids flow through a mixing apparatus to reduce the dust flow density to pf ₂ smoothly. This lowered density Pf ₂ and the injected gas V ₀ (Ni (based on the standard state) are also measured with a density measuring probe Of ₂ and with a

Measuring orifice V _{G (N)} measured. The bumpless mixing device has the same free flow cross section as the Delivery pipe and contains a porous gas-permeable, dust-blocking filter tube. It is also possible, in several bunker or a metering vessel leaving conveyor tubes in each Delivery pipe to determine the mass flow according to the method mentioned. On the basis of these measured variables V _G (ni, Pf ₁ , fr ₂ taking into account the amount of gas rh _G i in the dust stream at the beginning of Measuring section and the amount of gas rh _G 2 in the dust flow at the end of the test section, the mass flow by means of a simple Balance sheet approach to be determined. With the known solid grain density p _K and gas standard density p _{G (N} ) and by measuring the dust flow temperatures T ₁ , T ₂

and pressures p _1f p ₂ before and after the mixer results after conversion of the gas densities and volumes in the

Operating state (V _G2 , Pq ₁ , p _G2 ) the mass flow m _K. At higher system pressures and higher solids concentrations in the dense phase, a simple temperature

and pressure measurement, i.e., that then the heat capacity of the solid, if any, solid and gas different

Temperatures prevail, that neglected the relaxation effects and thus

Pi = Pz, T ₁ = T ₂ , p _G1 = Pg2 can be set. This results in a simplified calculation equation for the mass flow rh _K.

embodiment The invention will be explained with reference to three exemplary embodiments. In the drawing show: 1: Simplified block diagram of the mass flow measurement from a metering vessel at elevated system pressure. Fig. 2: Simplified block diagram of the mass flow measurement from a bunker. Fig. 3: Simplified block diagram of the mass flow measurement in the delivery pipe to a blast furnace wind. Embodiment 1

In the embodiment of the process according to FIG. 1, at an operating pressure P ₁ = 3.0 MPa, pulverized coal of a solid particle density Pk = 1400 kg / m ^{3 is} pneumatically transferred via nitrogen to the standard density p _G ( _N ) = 1.25 kg / m ³ a delivery pipe 3 promoted. In order to determine the mass flow m _K , injection gas 4 in the amount of V _G ( _N) = 250 m ³ ( _N ) / h is supplied to the dust flow in a mixing apparatus 5 located in the conveyor pipe 3 and the flow densities before and after the mixing apparatus 5 are radiometrically of one size measured from fti = 380kg / m ³ and p "= 280 kg / m ³ . The temperatures before and after the mixing apparatus 5 are approximately equal and are T ₁ ~ T ₂ = 353 K. From the measured data thus determines a process computer 2 a mass flow of 10t / h.

Embodiment 2

In an embodiment of the method according to FIG. 2, at an overpressure of P ₁ = 0.15 MPa from a bunker 1 pulverized coal of a solid particle density ρ * = 1400 kg / m ³ and an initial flow density Pn = 470 kg / m ^{3 is} pneumatically mixed with air with a standard gas density Pqini = promoted 1.293 kg / m ³ in a conveying pipe. 3 Immediately after the bunker outlet 5 injection gas 4 with V _g <ni = 29m ³ _(N) / h is added to the dust flow through a mixing apparatus, so that the flow density p «reduced to 280kg / m ³ and the pressure at the measuring point after the mixer 5 p ₂ = 0.10 MPa. The temperature before and after the mixing apparatus 5 is the same and is T ₁ = T ₂ = 313 K. The injection gas 4 is mixed with the dust stream at a speed of 5 cm / s

By means of a process computer 2 thus follows a mass flow of m _K = 10t / h.

Embodiment 3

In the execution of the method according to Figure 3 is at a pressure of P ₁ = 0.16 MPa from a dosing 1 coal dust a solid particle density Pk - 1400 kg / m ³ and an initial flow density Pf ₁ = 420kg / m ³ pneumatically by means of nitrogen with a standard gas density p _G mi = 1.25 kg / m ³ conveyed in delivery pipes 3, which lead to the tuyeres of a blast furnace.

Immediately after the departure from the metering vessel 1 is the dust flow of each conveyor tube 3 via a mixing machine 5 injection gas 4 with V _{G (N)} - 2.5m ³ _(N) / h added, so that the flow density йг reduced to 300kg / m ³ and the pressure at the measuring point after the mixing apparatus is 5 p ₂ = 0.10 MPa. The temperature before and after the mixer 5 is the same and is T ₁ * T ₂ «313K. The injection gas is added to the dust flow at a rate of 8 cm / s. By means of the process computer 2 thus follows a mass flow of m _K = 0.4t / h tube.

Claims (3)

1. A method for determining the mass flow of fine-grained materials, especially when transporting pulverulent and fine-grained fuels and other materials used in metallurgical processes arbitrary operating pressures to the tuyeres of the blast furnace, for heating Siemens Martin ovens, copper shaft stoves and similar metallurgical units and in metal baths Purpose of refining, alloying, refining and similar metallurgical processes, characterized in that for determining the process flow important mass flow rh «within a delivery pipe (3) for reducing the flow density p _f1 on p _f2 an injection gas (4) bumplessly via a mixing apparatus ( 5) is supplied and that the flow density Pf _1, the system pressure p _{1 f,} the temperature T ₁ immediately (after a bunker (1) and metering vessel 1), but (in front of the mixing apparatus 5) and the flux density p _f2, the system pressure p ₂ , the temperature T ₂ after the mixer (5) g emessen and together with the fixed values of the solid grain density Pk, the gas standard density Pg <n) »the measured value of the volume flow of the injection gas (4) a process computer (2) are input, which determines the mass flow rh _K according to corresponding calculation formulas. 2. The method of claim!, Characterized in that particularly in the dense phase conveying (p _f2> 160kg / m ³⁾ and / or at higher operating pressures {p _2> 0,6MPa) of the temperature difference T ₁ to T ₂ and the relaxation effect P ₁ to p _{2 are} negligible and correspondingly simplified calculation equations are used, wherein the measured values T ₂ , P2> Vg2 / Pg2 of the measuring points after the mixing apparatus (5) in the process computer (2) are entered. 3. The method according to claim 1 and 2, characterized in that by the mixing apparatus (5) which is equipped with a porous, gas-permeable, dust-blocking filter tube, the injection gas (4) diffusion-like, d. H. is introduced into the dust flow at a speed S "10 cm / s. For this 3 pages drawings