Method for pneumatic conveyance of powdered medium from ash catcher bins

FIELD: pneumatic conveyance method used, in particular, for removal of ash from heat-electric generating stations.

SUBSTANCE: method involves supplying air in upward conveyance path and moving powdered medium through conveyance pipeline by initially providing pneumatic pulse in upward direction to inlet valve at this path for enabling feeding of powdered medium to inlet portion of conveyance pipeline; providing action of pneumatic pulse upon this valve for closing thereof and moving powdered medium through conveyance pipeline. Inclined pipeline used as inlet portion has volume equal to or less than volume of receiver used for creating of pneumatic pulse enabling closing of inlet valve and feeding of powdered medium to conveyance pipeline.

EFFECT: increased distance of conveying materials, enhanced reliability in conveyance of materials and reduced consumption of gas.

3 dwg

 

The invention relates to the field of power engineering and can be used for the pneumatic transport of ash from hoppers of ash collectors.

The known method of the pneumatic powder-like environment, in which the filling of the supply tank powdered environment through the open top of the valve to limit the closing of the upper valve, powder fluidization medium in the supply tank and the displacement powdered environment through output valve [1].

The disadvantage of this method is the complexity of design, low reliability, a significant flow of gas to the powder fluidization medium.

The closest to the technical nature of the present method is a method of pneumatic conveying of powdered environment from bins of ash collectors, consisting in moving powder from bins in the transport pipeline, the powder fluidization medium and moving it along the transport pipeline, consisting of sections, each section after fluidization mentioned environment shall move in an upward flow, the removal of pseudoviruses agent in the upper cavity of the ascending part and moving at an angle to the next section [2].

The disadvantage of this method is the inability of the pneumatic transport to significant the major distance, high flow pseudoviruses agent due to its removal in the upper part of the sections.

The aim of the invention is the pneumatic powder-like environment over long distances with high reliability, reduction of gas consumption for pneumatic transport.

This goal is achieved by the fact that in the method of the pneumatic powder-like environment of the bins of ash collectors, consisting in moving powder from bins in the transport pipe, the air supply in an area and moving powdered environment transport pipe, the air supply in an area and moving powdered environment transport pipeline, perform when exposed to a first pneumonolysis in an upward direction to the inlet valve on this site to ensure powdered medium on the inlet section of the transport pipe, followed by the impact of pneumonolysis on this valve to close and move powdery environment transport pipeline, and as input the land use of an inclined pipe, the volume of which is chosen equal to or less than the volume of the receiver used to create pneumonolysis providing closing the input valve and the supply of powdered environment in transport pipelines is.

Given a set of features allows the pneumatic powder-like environment under the influence of pneumonolysis in the piston mode on the distance determined by the pressure in pneumonolysis.

The invention is illustrated in the drawing, which shows a device that implements the proposed method (figure 1).

Figure 2 and 3 depict, respectively, according to ΔP=f(uTand fT=f(uT), where ΔP is the differential pressure transport pipeline; uT- speed pneumatic transport; fTthe coefficient of friction of the flow of powdered environment.

The device has an inlet valve 1 is placed in the bottom cavity of the hopper, the tube 2 for supplying the upward flow of air to open the valve 1, the input section 3 of the transport pipe 4, a receiver 5 solenoid 6.

The operation of the device is accomplished in the following way. The air supply tube 2, and the pressure of the flow of powdered medium in the lower cavity of the hopper causes the opening of valve 1 and the receipt of powdered medium in the input section 3. After a definite time interval defined by the average time of filling in the cavity of the inlet pipe 3, a signal for opening the solenoid 6 (or from a clock generator, or from the level switch). Pneumosinus design pressure and volume is m, the relevant volume of the cavity of the receiver 5, enters the upper chamber of the valve 1, providing closure and eviction powdered medium in the transport pipeline. After removing pneumonolysis - closing valve 6, the valve 1, under the influence of the upward flow of air through the tube 2 and the pressure of the powder-like environment, opens and begins a new cycle of filling powder medium cavity of the inlet pipe 3. Regulation enabling the solenoid can also be a level switch mounted in the upper part of the inlet pipe 3, however, to simplify the design more appropriate to carry out the pneumatic transport when turning on the solenoid 6 and the clock signal generator (not shown).

Evaluation of the effectiveness of the developed method of the pneumatic transport was carried out at the cost of ash QTand airThe flow of ash (QT) was determined by the gravimetric method with single piston to its release into the measuring container for a measured time period. During testing it was noted the following.

When the pneumatic transport of ash to the implementation of continuous blowdown Plenum between cycles was recorded residual layer of ash ˜20 mm And in the case of pneumatic transport in the piston mode of the residual layer of ash was min who d ˜ 5 mm. in other words, the piston ash seemed to clear the pipeline from its residual layer, thereby eliminating the deposition of particles at low speeds expires.

For the transport pipeline lengths L1=18 mi L2=51 m time t changed within 9÷12, weight within 28÷31 kg

The calculated value of the flow QBrequired for the formation of the air piston and blowing ash from the pipeline was determined

where VPand VTP- volumes respectively of the receiver and the transport pipeline.

For transport pipeline L1=18 m

and for L2=51 m

Here

For L1=18 m

For L2=51 m

where ρBis the density of air.

As can be seen, with increasing the length of the transportation pipeline attitudedecreases (increases air flow). However, when continuous piston filing ash value of VTPreduced to values of VPthat determines the possibility of increasingto ˜800.

According to weight measurements of the average flow of ash through the tube ⊘76 mm when the piston mode up to 10 t/h is.

This allows to conclude that the high efficiency of the developed method of the pneumatic transport of ash in the piston mode.

According to these studies, the differential pressure on the transport pipeline is determined according to the expression

where ΔP - pressure drop, kg/cm2;

ε - porosity powdered environment;

L is the length of the transportation pipeline, cm;

fTthe coefficient of friction of the flow of powdered environment;

uT- speed pneumatic, cm/s;

D - hydraulic diameter, cm;

ρT- the material density of the particles, g/cm3;

g - free fall acceleration, cm/s2.

Using experimental results, the selected average value of fTfor optimal speed pneumatic transport, the porosity of the powder flow environment (piston), fT=3·10-3(figure 3).

Hence the pressure in pneumonolysis for transport on the calculated value of L is determined from the expression

where ΔR=Ru-Ra;

Puand Pa- pressure respectively pneumonolysis and the atmosphere, kg/cm2.

To ensure the objectives of the displacement portions powdered environment from the transport pipeline volume piston powdered environment - wholehouse 3 must be equal to or less than the volume of pneumonolysis, i.e. the volume of the receiver 5. Indeed, taking into account the obtained experimental by low values of fTfor powdered environment (ash electrostatic-catchers) when the pneumatic transport in pulsed mode, the effect of the inertia of the movement of the piston powdered environment after pulse exposure to air volume equal to the volume of the piston. However, the transport over long distances (100 m and more) identifies the need to increase the reliability to increase the exposure time by pneumonolysis to obtain a volumetric ratio of expenseswhereand- volumetric charges, respectively powdered environment and air.

Thus, by forming the piston mode of the pneumatic powder-like environment pneumonology supplied to the upper chamber inlet valve, possible to increase the reliability of pneumatic and reducing air flow.

Sources of information

1. USSR author's certificate No. 1239064, B 65 G 53/40, 1989

2. RF patent №2164491, B 65 G 53/16, 1998

Way pneumatic powder medium from the storage silos ash catchers, which consists in moving powder from bins in the transport pipeline, the supply air in the rising area and is the relocation of the powdery medium transport pipeline characterized in that the air supply in an area and moving powdered environment transport pipeline is executed under the influence of the first pneumonolysis in an upward direction to the inlet valve on this site to ensure powdered medium on the inlet section of the transport pipe, followed by the impact of pneumonolysis on this valve to close and move powdery environment transport pipe, and the inlet pipe using an inclined pipe, the volume of which is chosen equal to or less than the volume of the receiver used to create pneumonolysis providing closing the input valve and the supply of powdered medium in the transport pipeline.



 

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