GB2148858A

GB2148858A - Apparatus for measuring and controlling volume flow of fluidizable granular and/or powdered materials

Info

Publication number: GB2148858A
Application number: GB08423796A
Authority: GB
Inventors: Gyorgy Vigyazo; Lajos Gancs; Laszlo Angyan; Erno Harmath
Original assignee: Eroemue Es Halozattervezoe
Current assignee: Eroemue Es Halozattervezoe
Priority date: 1983-09-28
Filing date: 1984-09-20
Publication date: 1985-06-05
Also published as: IT8422882A0; DE3433488C2; FR2552542B1; DE3433488A1; AT385134B; IT1176841B; HUT34609A; ATA284284A; FR2552542A1; IT8422882A1; GB2148858B; GB8423796D0; HU188492B

Abstract

Apparatus for measuring and controlling the volume flow of fluidizable granular and/or powdered materials comprises a fluidizing chamber (2), an inlet (3) and an outlet (5) for the fluidizing gas, and a plurality of transfer openings (7) arranged in the side wall (6) of the fluidizing chamber (2) and discharging into a collecting chamber (8) having an outlet (9). The fluidizing chamber (2) is provided with either a sensor (10) for measuring the level or height of fluidized material in chamber (2) to give a direct measurement of the volume flow of the fluidizable material; or with a pressure sensor (11) to give an indirect measurement. <IMAGE>

Description

SPECIFICATION Apparatus for measuring and controlling volume flow of fluidizable granular and/or powdered materials The invention relates to an apparatus for measuring and controlling the volume flow of fluidizable granular and/or powdered materials. The apparatus according to present invention can be applied in particular while transporting the materials mentioned above, e.g. in pneumatic conveyor systems transporting flying ashes of thermal plants, for feeding, flying ashes and calcium hydrate and for mixing flying ashes and calcium hydrate in a predetermined ratio, respectively.

There are several methods for measuring the volume flow and/or the mass flow of granular and powdered materials, respectively consisting of two or more components and feeding them in a predetermined ratio. According to the oldest known method each material flow has been weighed intermittent and after weighing the components have been mixed. Through the apparatus working by the method mentioned above the task set has been solved, but the disadvantage of them lies in the large dimensions and in the intermittent operation influencing the disadvantageously the homogeneity of the mixture. Further disadvantage of the known method lies in that, changing in time of the primary material flow cannot be synchronized with changing of other secondary material flows. Using the known methods cannot be ensured continuous function relation between the primary and secondary material flows.To meet this requirement it would be needed to weigh very little quantity of primary material, which cannot be realized in the practice at all or only very difficult.

There are known apparatuses conveying the primary and secondary material flows by feeder including rotary chambers, and controlling the volume flow is performed by changing the speed of rotary chamber feeder, wherein the speed of each rotary feeder conveying one or more secondary material flow is depending on the spped of the rotary feeder conveying the primary material flow.

The apparatus mentioned above has a lot of disadvantages. The rotary feeder are friction-sensitiv, in particular in cases of pressure difference and counter-flow between the inlet stub and outlet stub. A further disadvantage lies in that owing to the low speed of rotation very expensive means are needed to drop the speed.

There are several apparatus according to the technical literature, where the volume flow of conveying processes is measured by measuring the impulse force. According to the equation of motion of Newton changing of the volume flow of a material means changing of the force for cases when speed is changing. It means that if in the way of the material flow balancelike suspended buffle plate is arranged and the material of constant speed reaches and leaves this plate, changing the material flow of the material effects changing the force balancing the buffle plate. The change of the force can be transformed into changing of electrical signals, so controlling the secondary volume flow can be solved too.The graeteset disadvantage of the known measuring instruments for measuring mass flow and applying buffle plate, lies in that they are operating of the same material flow, so in cases of the speed is changing the apparatus is to be calibrated and in cases when the speed is always changing the known apparatuses cannot be applied at all.

Further disadvantage lies in that change of the densitiy of the material of the material flow needs calibration too, and in cases if the densitiy is changing the apparatus cannot be applied at all.

It is therefore one of the principal objects of the invention to develop an apparatus which eliminates the drawbacks of the known apparatuses and enables measuring the momentary value of volume flow of granular and/or powdered materials and its change in time of an accurancy being sufficient in the practice thus-co-ordinating primary material flow and one or more secondary material flows.

The task to be solved can be determined in such a way, that the simple contruction of the apparatus should ensure measuring the volume flow of in any way fluidizable and/or powdered materials so, that changing of the flow speed and density of the material should not hinder measuring.

The aim set has been solved by an apparatus being able to measure and control of the material flow of granular and powdered materals comprising fluidizing chamber, inlet means and outlet means for the fluidizing gas.

The essence of the invention lies in that at least one transfer opening of particularly controlable cross-section is arranged in the fluidizing chamber, and said transfer opening is discharging into the collecting chamber having an outlet stub, further the fluidizing chamber is provided by niveau sensor measuring the level height being in direct proportion to the volume flow of the fluidized material.

It is preferable according to the invention if said transfer openings are being arranged in the said side wall of the fluidizing chamber perpendicularly or nearly perpendicularly, parallel to the equipotential surface of the gravitational field.

It is further preferable according to the invention if pressure sensor measuring the pressure of the fluidizing gas under the layer, the level height of which being proportional to the fluidized material, is connected to the inlet means for introducing the fluidizing air.

It is further advantageous according to the invention if at least one layer control means is introduced into the collecting chamber, where said layer control means controlling the volume flow of the secondary mass flow and is connected to the niveau sensor and resp. pressure sensor through known transmitter and control unit.

According to the invention it is preferable if having a further outlet-stub for the fluidizing air.

If is preferable it introduction secondary volumeflow is arranged separated from the apparatus.

For fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which Figure 1 shows a lingitudinal cross-section of a preferable embodiment according to the invention, Figure 2 shows an elevational cross-section of a developed embodiment of the apparatus shown in Figure 1.

As shown in Figure 1 the apparatus for measuring and controlling volume flow of fluidizable granular and/or powdered material according to the invention comprising supply stub 1 for inlet the volume flow of the primary material. The supply stub 1 is arranged above the fluidizing chamber 2 of the apparatus, while in the lower part of the chamber 2 inlet means 3 is arranged for the fluidizing gas in this cases for the air. Over the inlet means 3 is arranged insert 4 filling the whole cross-section of the chamber 2. According to the embodiment shown there is an outlet pipe stub 5 for the fluidizing gas, in this case for the air arranged at the upper part of the chamber 2. In the side wall 6 of the fluidizing chamber 2 transfer openings 7 are arranged perpendicularly letting the fluidized primary material through.The transfer openings 7 connect the fluidizing chamber 2 with the collecting chamber 8 on the bottom of which outlet stub 9 is arranged. There is known niveau sensor 10 arranged in the fluidizing chamber 2 for measuring the level height of the fluidized primary material, and a further pressure sensor 11 is connected to supply inlet means 3 for fluidizing air measuring the pressure being proportional to the level height of the fluidized primary material.

According to the preferably embodiment of the invention shown in Figure 2, there is a further supply stub 12 arranged at the upper part of the collecting chamber 8 being connected the tank/not shown of the secondary material/si. The supply stub 12 is connected through the control unit controlling mass flow of the secondary medium, in this case through the layer control 13 connected by means of known transmitter and control unit to the niveau control 10 and pressure control 11.

The operation of the apparatus according to the invention can be described by static and dynamic state diagram to a known through flow tank. The level height of the tank is changing e.g. in case when constant volume flow is flowing out of a tank through at least one opening and the input volume flow is changing. The change in the level height can be measured directly by measuring the level by a level sensor, or indirectly by measuring the pressure of the fluidizing gas e.g. air. The result shows the momentary value of the volume flow, and the result of the measurement generates directly a control impulse being connected to an other control unit controlling the volume or mass flow of an the secondary material flow.The dimensions and number of the transfer openings 7 are to be determined so, that in case of a maximal volume flow the sum of the volume flows passing through the transfer openings 7 in dependence on the height of the fluidized materials column should be equal to the fluidized volume flow of the entering primary material flow. The level height in the fluidizing chamber or the static pressure of the fluidizing air determines a primary volume flow to which one ore more secondary mass flow can be ordered. Changing the entering primary volume flow in positiv or in negativ direction, further transfer openings begin to operate or stay empty. It means that the fluidized function, and after settling static state the change of the niveau can be measured, and the secondary mass flow can be controlled proportional to the measured value.The powdered and/or granular material introduced into the fluidizing chamber 2 behaves like liquid during fluidization in the gravitational field and thus flows out through the said transfer openings 7 according to the hydraulic laws if fluidizing gas e.g. air is introduced under the fluidizing insert 4 through the inlet means 2 for fluidizing gas. The fluidizing air is moving off the fluidizing chamber 2 through the pipe stub 5 or together with the primary material through the openings 7. As the primary material is being in the fluidizing chamber 2 in fluid state, behaves in the gravitational filed like liquids and flows through the openings 7 formed in the side wall 6 into the chamber 8 and the speed of the fluidized material is proportional to the square root of the level height depending on the volume flow.

The level height of the fluidized primary material in the chamber can be measured by the niveau sensor 10. The level height is always, as mentioned above, proportional to the current volume flow. As the niveau sensor 10 measures continuousiy the level height in the chamber, it is possible to pay attention continuously to the volume flow e.g. to its changing in dependence on the time. Measuring the level height of the fluidized primary volume flow any way you want, the output signal of the sensor can be transformed into electric signal which gives information referring to the volume flow, and enables to control further secondary material flow by transforming the measured value into a control signal and controlling the secondary volume flow entering the supply stub 12 by means of layer control means 13.

The advantage of the apparatus according to the invention lies in that it can be applied for measuring and controlling of volume flow of fluidizable solid and liquid materials, and that the inputs of secondary mass flow in technological conveyor systems can be worked out independent of the apparatus.

Claims

1. Apparatus for measuring and controlling the volume flow of fluidizable granular and/or powdered materials, comprising a fluidizing chamber, inlet means and outlet means for the fluidizing gas, and at least one transfer opening of particularly controllable cross-section arranged in the side wall of the fluidizing chamber, discharging into a collecting chamber which has an outlet, wherein the fluidizing chamber is provided by a level and/or pressure sensor for measuring the level of the flui dized material in direct proportion to the volume flow of said material.

2. Apparatus according to claim 1, wherein said at least one transfer opening is arranged in the said side wall perpendicularly or nearly perpendicularly to the longitudinal axis of the fluidizing chamber, parallel to the equipotential surface of the gravitational field.

3. Apparatus according to claim 1 or 2, wherein the pressure sensor is positioned to measure the pressure of the fluidizing gas beneath the support for the fluidized material, the height of which is proportional to the fluidized material.

4. Apparatus according to any preceding claim, wherein at least one layer control means is provided in the collecting chamber for controlling the volume flow of the secondary material and is conected to the level sensor and/or pressure sensor through a transmitter and control unit.

5. Apparatus according to any preceding claim, wherein a discrete outlet is provided for the fluidizing air.

6. Apparatus according to any preceding claim, whrein the introduction of the secondary material is arranged separately.

7. Apparatus substantially as herein described with reference to and as shown in Figure 1 or Figure 2 of the accompanying drawings.