GB2121938A

GB2121938A - Drying apparatus

Info

Publication number: GB2121938A
Application number: GB08217436A
Authority: GB
Inventors: Laszlo Varga; Sandor Krekacs; Janos Latorcai; Zoltan Palfi; Istvan Fledrich
Original assignee: BUDAPESTI MUESZAKI EGYETEM; Budapesti Muszaki Egyetem
Current assignee: BUDAPESTI MUESZAKI EGYETEM; Budapesti Muszaki Egyetem
Priority date: 1982-06-16
Filing date: 1982-06-16
Publication date: 1984-01-04
Also published as: GB2121938B

Abstract

The surfaces of bodies are dried and adjusted in temperature by streaming air or steam, having a temperature within the range of +/-10 DEG C of the surface temperature to be reached, e.g. from a nozzle or a plurality of nozzles. Preferably the average velocity of the stream of air or steam is according to a stated formula.

Description

SPECIFICATION Method and apparatus for removing humidity adhered to surfaces of bodies and simultaneously for adjusting the surface temperature of the bodies The invention relates to a method for removing the humidity adhered to the surfaces of bodies and simultaneously for adjusting the surface temperature of the bodies to a previously determined surface temperature. This adjusting of temperature is called tempering, too. The invention relates to an apparatus for the same purpose, as well.

As it is well known, a technological process has often as its part a cleaning and drying, i.e.

humidity removing operation and, thereafter, a temperature adjusting dperation, too. In the production of electric discharge lamps such as neon tubings, for example, a washing and drying procedure is followed by a deposition by evaporation in vacuum. For the latter, a previously determined temperature of the tubing is required.

In all cases similar to this, the drying and the tempering of the surface are achieved in two separate working operations. The humidity adhered to the surfaces of the bodies is removed by diffusion drying and the surface temperature is adjusted to the previously given value by a caloric process.

The efficiency of the diffusion drying is determined, among others, by the temperature of the drying medium. Therefore, a relatively warm drying agent is used which reduces the time of the operation as well as the constructional measurements of the dryer equipment. As a result of this, the surface temperature of the dried body will be enlarged after drying. For reaching the technologically optimal surface temperature, the dried body surface must subsequently be cooled down.

As it is obvious, a great amount of energy is consumed for drying (and, consequently, warming up) and, subsequently, for tempering (i.e. cooling down) the body to be treated. The high temperature for the efficient drying and the low temperature for the efficient tempering are, thus, in contrast. To improve this disadvantage, an optimum was sought for in the level of these temperatures which is in most cases impossible to determine, only a compromise can be reached. The above said contradiction can not be resolved.

Accordingly, it is an object of this invention to provide a method wherein the subsequent operations of drying and adjusting the surface temperature are not in contradiction, i.e. wherein the first operation is not unbeneficial to the second one.

The basic idea of the invention is in that, instead of diffusion drying, a drying procedure with air or steam flow should be used.

The knowledge of this idea resulted in a further object to be achieved by this invention. Further to what have been said hereinabove, a method should be provided wherein the drying and temperature adjusting procedure will be fulfilled in one and the same operation.

As it is well known, the drop in pressure of a medium streaming along another medium results in forces perpendicular to the direction of flow. As an effect of these the streaming medium tends to take away with him this second medium. If this second medium is the humidity adhered to the body surface to be dried and the streaming medium is air or stream, the humidity can be removed from the surface without the need of other drying procedure such as diffusion drying. With other words, removing the humidity is, possible not only by a caloric process, i.e. by increasing the surface temperature of the body but by the appropriate drop in pressure of the streaming medium, too.

Furthermore, if the temperature of the streaming medium is within a narrow range of the predetermined surface temperature of the tempering, the drying and the temperature adjusting can be fulfilled simultaneously, in the same working operation.

For the possibility of practicai realization, an extensive search and experimental activity had started by the applicant for determining the flow pattern and, for this, the flow velocity of the streaming medium.

It has been found that the above said objects will simply be achieved if air or steam are streamed along the surfaces of the body to be treated, if the temperature is within a range of + 10 degrees centigrade of the surface temperature to be achieved and, furthermore, if the average velocity of the streaming air or steam has a value as follows::

wherein, arl is the average velocity of stream of the air or steam, g is the gravitational acceleration (g = 9,81 m/s2), tv is the dynamic viscosity of the humidity in the state of its removal, G1 is the specific weight of the air or steam in the state of removal of the humidity, v,, is the velocity of stream of the humidity at radius Rt, Rb is the hydraulic radius of the humidified surface, R, is the hydraulic radius of the interface of the humidity and the air or steam, f, is the degree of saturation of the air or steam (or relative humidity, having a maximum value of 1), c is a constant calculated as follows::

wherein 0,001 5 < k < 3 is the modified resistance coefficient Further object of the invention is to provide an apparatus for removing the humidity adhered to the surfaces of bodies and, simultaneously, for adjusting the surface temperature of the bodies to a predetermined surface temperature. For simple reaching of this object, a nozzle or a plurality of nozzles are provided for conducting air or steam along the surface of the body to be treated, the air or steam having a temperature within the range of 1 10 degrees centigrade of the surface temperature to be achieved.

Further objects, features and advantages of this invention will be described herein under in greater detail in connection with exemplified embodiments and with reference to the attached drawing. In the drawing, Fig. 1 to 1 9 show several connection diagrams of various exemplified embodiments.

As it is clearly apparent from what have been said hereinabove, at least two conditions must be satisfied for achieving the object of the invention: the temperature of the streaming air or steam must be within a temperature range of +10 degrees centigrade of the surface temperature to be reached and, on the other hand, the average velocity of stream v1 must have a value calculated according to the formula given in the main claim. For this, a nozzle or a plurality of nozzles are inevitably needed. But, in most cases, the pressure and temperature of the air or steam aviable are not convenient for the purposes of the invention. For changing these features, a heat exchanger and a medium transporter are needed.

In Fig. 1, a medium transporter is shown by 1, a heat exchanger at 2, a nozzle at 3 and a body to be treated or workpiece at 4. These elements are connected in series in the sequence as said above. The workpiece 4 is here a hollow one, e.g. a tube from the inside of which the humidity should be removed.

With medium transporter 1 and with nozzle 3, the average velocity v1 and the flow pattern in the inside of the tube are generated. With heat exchanger 2, the prescribed temperature is achieved. Nozzle 3 blows the air or steam with the necessary speed and temperature into the tubular workpiece 4. Running through it, the air or steam suffers a given drop in pressure, for the purpose of which the average velocity V, is calculated. As stated above, this drop in pressure of the streaming medium has a result of taking the humidity adhered to the surface with him. Thus, the humidity adhered to the inner surface of the tubular workpiece 4 is "blown out" by the air or steam. In the course of this removing of humidity, the surface temperature determined previously according to the needs of the further technological process is reached, too.Thus, in one and the same working operation, the humidity is removed and the surface temperature is adjusted as well. A medium path of the air or steam leaving the workpiece 4 is shown at 6 and a liquid path also leaving the workpiece 4 at 5 with a dashed line.

In Fig. 2 the nozzle 3 and the workpiece 4 are shown in cross section. In this example, the heat exchanger 2 is connected before the medium transporter 1 and a drip separator 1 2 is connected into the liquid path 5 and medium path 6 leaving the tubular workpiece 4 for separating the liquid content of the streaming air or steam. As a result of this, the air used in the process can be redirected and used again.

In the example of Fig. 3, the nozzle 3 is built into a sealing or gasket 7 which interconnects the inner surface of workpiece 4 and nozzle 3. With this, a backflow of the streaming medium is prevented and a better flow pattern within the workpiece 4 is provided. In addition, a suction nozzle 8 is arranged behind the workpiece 4, with the aid of which the optimal flow pattern can be maintained even with long workpieces 4, in the final part of them, too.

In Fig. 4, not only nozzle 3 and workpiece 4 but also suction nozzle 8 are shown in cross section. In this example, drip separator as in Fig. 2 is connected behind suction nozzle 8, too.

In Fig. 5, a hollow workpiece 4 is shown having a shape of cross section other than tube.

Assuming that the air or steam used here has a temperature within the range of 110 degrees centigrade of the surface temperature of the workpiece 4 to be reached, no heat exchanger is required in the circle. However, it has been found that the humidity removed from the inner surface of the workpiece 4 tends to drop down or flow back on the outer surface at the end opening of the workpiece 4. For preventing this occun ence, auxiliary nozzles 9 are provided around the end opening of workpiece 4, the medium paths 6 of which take with them the humidity flowing out here. Nozzles 3 and auxiliary nozzles 9 are connected in parallel to medium transporter 1.

With the cup-shaped workpiece 4 in Fig. 6, a long nozzle 3 is used directing the air or steam from medium transporter 1 into the inside of the cup. The opening of the cup-shaped workpiece 4 is closed by a gasket 7 through an opening of which the air and the humidity removed from the inner surface of the cup are leaving.

The same kind of nozzle 3 with another gasket 7 and with a bulb-shaped workpiece 4 is shown in Fig. 7. Medium path 6 and liquid path 5 leave'through an outlet orifice 10 provided in the workpiece 4 itself.

In the example of Fig. 8, a system for treating the inner surface and, at the same time, the outer surface of a workpiece 4 is shown. A rod-like workpiece and a tubular one are arranged in a hollow guiding piece 1 5 in which the desired flow velocity and pattern are produced by medium transporter 1 such as blowing fan, by nozzle 3, by pieces 1 6 increasing the resistance of flow of medium and being fixed to the inner surface of hollow guiding piece 1 5 and by suction nozzle 8. The streaming air or steam enters the hollow guiding piece 15, flows through it and subsequently through suction nozzle 8 as well as drip separator 12. In the course of this, the humidity adhered to the.inner and outer surfaces of the workpieces 4 is removed, and the liquid is separated from the air in drip separator 12.

In Fig. 9, a workpiece 4 is illustrated, the one measurement of which being perpendicular to the direction of flow of air or steam is much greater than that in direction of flow. For the desired flow pattern, piece 16 increasing the resistance of flow is arranged in the inside of workpiece 4. In this case, piece 6 means a kind of choking or throttling causing the necessary drop in pressure of streaming air or steam along workpiece 4. Auxiliary nozzles 9 are arranged, too, the purpose and function of which being the same as in Fig. 5. However, the auxiliary nozzles 9 are connected here to a separate blast transporter 14 feeding them with air or steam. Furthermore, they have an interchangeable nosepiece 11 with the help of which the flow pattern of auxiliary nozzles 9 can always be adjusted to the special demands of various workpieces 4.The liquid path 5 and medium path 6 of the system are led through drop separator 12.

In the example of Fig. 10, a plurality of nozzles 3, workpieces 4, auxiliary nozzles 9 and suction nozzles 8 is fed with streaming air or steam by medium transporter 1 through heat exchanger 2. On the outlet side, the suction nozzles 8 are connected to a common drip separator 1 2 wherein the liquid path 5 is separated from the medium path 6.

Fig. 11 and 1 2 show the system in this invention with redirecting the medium path 6 and repeatedly using the air. The liquid removed from the surfaces of the workpiece 4 leaves through drip separator as liquid path 5. In Fig. 12,auxiliary nozzles 9 are provided, too.

In Fig. 12, a system as in Fig. 1 1 and Fig. 14 one as in Fig. 12 are shown, however, without the redirection of medium path 6. Here, a suction transporter 1 3 is provided with which the air leaving the drip separator 1 2 is taken away from the system, e.g. into the circumference.

As it is obvious from Fig. 1 5, suction transporter 13 can be used with a system shown in Fig. 11 for redirecting medium path 6 to medium transporter 1.

Furthermore, the auxiliary nozzles of Fig. 1 4 can be fed by a separate blast transporter 14 as shown in Fig. 1 6. On the other hand, they can be connected to the medium path 6 outlet of drip separator 12 with the interconnection of suction transporter 13. The auxiliary nozzles 9 are fed here with the regained air pressurized as necessary by suction transporter 1 3.

if the air or steam used in this invention have the desired temperature and if the nozzle 3 and the shape of working piece 4 make it possible, only suction transporter 1 3 alone is enough for providing the desired velocity and pattern of stream in the system, as it is shown in Fig. 1 8.

As illustrated in Fig. 19, more than one workpiece 4 can be treated with one nozzle 3 and one suction nozzle 8 both having a proper design.

The examples described hereinabove are only some of the variation possibilities within the scope of claim of this invention.

Claims

1. Method for removing humidity adhered to surfaces of bodies and simultaneously for adjusting the surface temperature of the bodies to a previously given value, wherein air or steam having a temperature within a range of +10 degrees centigrade of the surface temperature to be achieved being streamed along the surface of the body, a velocity of stream of the air or steam being calculated according to the following formula::

wherein v1 is the average velocity of stream of the air or steam, g is the gravitational acceleration (g = 9,81 m/s2), tv is the dynamic viscosity of the humidity in the state of its removal, G, is the specific weight of the air or steam in the state of removal of the humidity, Vvi is the velocity of stream of the humidity at radius R1, Rb is the hydraulic radius of the humidified surface, R, is the hydraulic radius of the interface of the humidity and the air or steam, f1 is the degree of saturation of the air or steam (or relative humidity, having a maximum value of 1), c is a constant calculated as follows:

wherein 0,0015 < k < 3 is the modified resistance coefficient.

2. A method according to Claim 1, wherein the air or steam being streamed through a nozzle or a plurality of nozzles and/or a medium transporter and/or a heat exchanger and/or a drip separator.

3. An apparatus for removing the humidity adhered to surfaces of bodies and simultaneously for adjusting the surface temperature of the bodies to a previously given value, wherein a nozzle or a plurality of nozzles being provided for streaming air or steam having a temperature within a range of +10 degrees centigrade of the surface temperature to be achieved along the surface of the body.

4. An apparatus as claimed in Claim 3, wherein a heat exchanger being provided and the nozzle(s) being connected to an outlet side of the heat exchanger.

5. An apparatus as claimed in any one of Claims 3 or 4, wherein a medium transporter for the air or steam being provided and the medium transporter being connected between the heat exchanger and the nozzle(s) or to an inlet side of the heat exchanger.

6. An apparatus as claimed in any one of Claims 3 to 5, wherein a drip separator being provided in an outlet medium path of the apparatus behind the body to be treated.

7. An apparatus as claimed in any one of Claims 3 to 6, wherein a suction nozzle or a plurality of suction nozzles being provided in the medium path.

8. An apparatus as claimed in any one of Claims 3 to 7, wherein an auxiliary nozzle or a plurality of auxiliary nozzles being provided in the vicinity of an end of the body to be treated being near to an outlet of the apparatus.

9. An apparatus as claimed in any one of Claims 3 to 8, wherein a gasket being provided between the nozzle(s) and the body to be treated.

1 0. An apparatus as claimed in any one of Claims 3 to 9, wherein a hollow guiding piece being provided for receiving the body to be treated.

1 An apparatus as claimed in any one of Claims 3 to 10, wherein a blast medium transporter being connected to the auxiliary nozzle(s) and/or a suction medium transporter being connected to the suction nozzle(s).

1 2. An apparatus as claimed in any one of Claims 3 to 11, wherein a piece increasing the resistance of medium being provided in-the stream path of the medium in the vicinity of the surface of the body to be treated.

1 3. An apparatus as claimed in any one of Claims 3 to 12, wherein the auxiliary nozzle(s) having a replaceable nosepiece.

14. A method according to Claim 1 for removing humidity adhering to the surfaces of bodies substantially as hereinbefore described.

1 5. Apparatus according to Claim 1 for removing the humidity adhering to bodies substantially as hereinbefore described with reference to the accompanying drawings.