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INVENTION
Russian Federation Patent RU2280821
METHOD OF HEATING AND AIR FLOW DEVICE
Name of the inventor: Semenov Anatoly Leonidovich (RU); White Sergey (RU); Belyanin Nikolai Mikhailovich (RU); Kotelnikov Yuri Leonidovich (RU)
The name of the patentee: Federal State Unitary Enterprise ". The Central Institute of Aviation Motors named after PI Baranov" (RU)
Address for correspondence: 111116, Moscow, ul. Aviamotor, 2, FSUE "CIAM. Baranov," Intellectual Property Department
Starting date of the patent: 2004.12.22
The invention relates to the field of heating of industrial gases, including air, at high flow rates by electrothermics. The process air flow heated to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s, the heating element includes a heating electric current and heat the heated air flow Joule heat, with the heated air stream is passed inside a heating element symmetrical flow directed towards each other and form a common stream of heated air flows through the merge counter, selecting a common heated stream into the space along the center line between the heating elements. Device for heating a stream of air to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s comprises three-phase electrical power source, the hollow heating elements, each of which is connected to one phase of three-phase power supply, manifolds for the supply and exhaust air, to which are connected the ends of the hollow heating elements and the manifold air inlet is in the form of at least two symmetrical risers, each of which is connected the hollow heating element, and each hollow heating element is divided into at least two identical sections along a common longitudinal axis and connected opposite ends to the corresponding standpipe manifold for supplying air, which is the input of each hollow heating element, and the outlet manifold, located along the central axis of the device symmetrically with respect to the risers inlet manifold and the two sections of each heating element electrically connected in series and electrically isolated from the inlet and outlet manifolds insulators fixed on every floor heating element. The technical result of the invention is to reduce the inlet pressure to heat the feed air stream by reducing the pressure losses along the length of the heating element.
DESCRIPTION OF THE INVENTION
The invention relates to the field of heating of industrial gases, including air, and more particularly concerns the means for heating high-temperature air and / or industrial gases (hereinafter - the air) at high flow rates by electrothermics.
The invention can be applied to heat the air and its use in various industrial applications, including air-conditioning systems in stationary furnaces, in drying systems. It can be used for research purposes, for example, in wind tunnels.
Known devices for heating the air with electricity.
Known resistive heaters air flow type (ELECTRIC).
Heating of air (or other fluid) in such heaters is performed by Joule heat at the heating air flushing stream (fuel) elements - a relatively large conductor with an electrical resistance through which an electric current passes.
Electric heaters are known in which a plate-like heating elements spiral tube is used as a heating element, wire mesh, etc.
Known electric heaters fluid, where the heating elements are applied in the form of a corridor tube bundle tubes staggered tubes in transverse or longitudinal flow of air.
Known electric heater fluid, which contains a pipe heated by the current, connected at the ends with the teams of collectors, and conductor rails (auth. St. №117394, MKI F 24 N 3/04, publ. 1958).
There is a method of heating the flow of air to a temperature above 500 ° C, which comprises heating the heating element of electric shock and heat the heated air flow Joule heat, and the heated air stream is passed inside a heating element (auth. St. №1776930, MKI F 24 N 3/04 , publ. 1992).
Known electric heater gas (auth. St. №1776930, ICI F 24 N 3/04, publ. 1992), which contains a collector connected to a collection of hollow tubular heaters are connected to conductor rails disposed on the heaters to be offset from the collector, wherein conductive Tyres designed as shunt connecting the tubular heaters, electrical resistance of 5-10 times smaller than the electric resistance heaters on the shunted portion.
The known method for heating the air flow and electric heater can be used advantageously in the test plants, such as wind tunnels, for test and research purposes.
The object of the invention - to create a method and a device for heating the air stream to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s for industrial use in industrial installations. Another objective was to provide an economical heating of such air flow.
The difficulty of solving the problem is that high temperature heating air stream of large mass flow, how are these values is required to achieve a high flow (rate) of heat transfer, which is ensured by increasing the flow rate, but this causes a strong increase in aerodynamic drag, which is proportional to the square of the flow velocity a heating element. When heated air stream mass flow 0.3 kg / s, for example, the phase of a three phase electrical current to the floor heating element to a temperature of 700 ° C, the pressure loss will be from 35 to 40 bar, which requires inputting air into the heating element flow with pressure above 40 atm. Ensuring the process of heating and movement of the air flow through the hollow heating element in this case, should be provided by the presence of extraneous source of compressed air. Such a source of compressed air in industrial environments are usually compressed air systems. In industrial environments on economic and technological requirements it is usually not advisable to use (not used) compressor units with a pressure higher than 20 atm. The need for a high pressure inlet for the high temperature heating and high-speed air flow, prevents the use of the invention, known in industrial environments in industrial installations and large pressure loss at this further causes diseconomies such heating.
The authors found that when such a process air preheater by splitting the flow of heated air, for example, in «n» symmetrical flow velocity in the heating element is reduced in «n» times, the pressure loss at the same time as proportional to the square of the velocity, decreases «n 2" times, wherein, in carrying out heating according to the present invention is achieved by heating the entire mass flow to the maximum design temperature of the heating
The technical result of the invention is to reduce the inlet pressure to heat the feed air stream by reducing the pressure losses along the length of the heating element.
This object is achieved in that the process air flow heated to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s, the heating element comprising a heating electric current, and the heated air flow heat dissipation of Joule heat, and the heated air stream is passed inside heating element according to the invention the heated air is supplied to the heating element symmetrical flow directed towards each other and form a common stream of heated air flows through the merge counter, selecting a common heated stream into the space along the center line between the heating elements.
The heating of the heating element of an electric current phase can be carried out more than 0.3 MW capacity.
Advantageously, the electric current is deduced to the maximum capacity in less than 20 seconds.
This object is achieved by the fact that the device for heating the air stream to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s, comprising a three-phase electrical power source, the hollow heating elements, each of which is connected to one phase of three-phase electric supply manifolds for supply and exhaust air to which are connected the ends of hollow heating elements, according to the invention a collector for the air inlet is in the form of at least two symmetrical risers, each of which is connected the hollow heating element, and each hollow heating element is divided by at least two identical sections disposed along a common longitudinal axis and connected opposite ends to the corresponding standpipe manifold for supplying air, which is the input of each hollow heating element, and the outlet manifold, located along the central axis of the device symmetrically with respect to the risers inlet manifold, and the two sections of each heating element is electrically connected in series and electrically isolated from the inlet and outlet manifolds insulators fixed on every floor heating element.
Advantageously, the insulators were mounted on each floor heating element without clearance.
Advantageously, and each insulator has been made of a composite fabric material based on silica.
Furthermore it is advisable that each hollow heating element made of a conductive metallic material based on stainless steel.
Each hollow heating element may have a length of 5 to 10 meters.
Advantageously, the outer diameter of the hollow of each heating element was 11 to 20 mm.
Feasible and that the internal diameter of each hollow heating element was from 10 to 18 mm.
Advantageously, as the source of three-phase electric power source was applied power above 0.9 MW and the current strength above 1000 A.
Profitable and that the electric current to the output to a position of maximum power in less than 20 seconds.
Further, the invention is further described by examples of its implementation and the attached drawings, in which:
Figure 1 shows a schematic diagram of the installation for heating the air flow according to the invention
2 - view of the apparatus for heating the air flow according to the invention of the arrow A Figure 1
3 - view of the apparatus for heating the air flow according to the invention (variant)
4 - is a sectional view with the arrow in Figure 3.
The process air flow heated to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s is as follows.
Heat hollow heating element is supplied into the heating element of the air flow of the electric current phase. The heating of the heating element of an electric current phase can be carried out more than 0.3 MW capacity.
Electric current is output to the maximum power in less than 20 seconds. The process of entering the operating mode with the heating element is supplied into an air stream is less than 40 seconds.
According to the invention the heated air is supplied to the heating element symmetrical streams directed toward each other. With the passage of air inside the heating element, heat transfer occurs to the heated air flow Joule heat, whereby the output of the heating element, its temperature rises above 500 ° C. Counter heated air flows merge in a common heated stream, selecting a common heated stream into the space along the center line between the heating elements.
Device for heating a stream of air to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s (1) according to the invention comprises a source of three-phase power supply 1, the hollow heating elements 2, each of which is connected to one phase of a three phase source supply. Each hollow heating element 2 divided into at least two identical sections 3 and 4, arranged symmetrically along a common longitudinal axis (not shown). However, as a variant, it is possible arrangement of sections 3 and 4 symmetrically sloping. As shown in Figure 2, the heating element 2 is divided into two sections - section 3 and section 4, the arcuate sections are made. The heating element 2 may be divided into more than two sections. (As shown in Figure 3, the heating element 2 is divided into 4 sections.) Each heating element section - Section 3 and Section 4 - 5 connected busbar 5 and 1 with one phase of three-phase power supply 1. The busbar tire 5 in Figure 1 illustrates the .1 schematically. The nature of her role carries a flange 10 (Figure 2). The device contains manifold 6 for supplying air, which is in the form of two risers 7, each of which is connected cavity of hollow heating elements 2, and each of which is the input of each of the hollow heating member 2, outlet manifold 8, located along the central axis device for discharging heated air symmetrically about 7 downcomer inlet manifold 6 for supplying air. Each hollow section of the heating element - Section 3 and Section 4 - electrically interconnected in series and electrically isolated from the inlet and outlet manifolds insulators 9 fixed to the floor each heating element 2.
As shown in Figure 4, the insulators 9 are mounted on each floor heating element 2 without a gap and bonded flange 10. As a material for the manufacture of composite insulators 9 fabric is applied based on silica.
Each hollow heating element 2 is made of a conductive metallic material based on stainless steel. The inner diameter of each hollow heating element ranges from 10 to 18 mm and an external diameter - of 11 to 20 mm, and the length - from 5 to 10 m.
The device operates as follows and implements the method according to the invention.
Supplied to the heating element 2 from the electric current phase of three-phase power supply 1, a heating element which heats up the calculated temperature.
The air flow enters the manifold 6 is divided into symmetrical flows entering the risers 7, in which it is further divided into symmetrical flows entering the cavity sections 3 and 4 of the heating element 2. When the passage of air inside the heating element, heat transfer occurs to the heated air flow Joule heat, whereby the output of the heating element, its temperature rises above 500 ° C. Heated air flows from sections 3 and 4 are merged into a common stream of heated outlet manifold 8, from which air is heated and then can be used in industrial applications in industrial settings.
For operation of the device is important to ensure the symmetry of the flows to meet each other to ensure uniformity of mass velocity field in the cross sections of the cavities of the heating element. In the heating element according to the invention, specific heat, such as per unit volume can be considered almost constant for a given section, and therefore uneven mass velocity inevitably leads to unevenness of the temperature field and heat transfer coefficients, causing non-uniformity of temperature of the heating element - local overheating, which is capable of lead to its destruction.
Specific examples of a method for using the device according to the invention in Figure 1.
Example 1 is supplied to each heating element 2 the electrical current capacity of more than 0.3 MW of phase three-phase electric power source 1, a 1 MW and the current strength of 1000 A and at the same time to the input manifold 6 is fed a stream of heated air to the mass flow rate of 1 kg / s . air flow pressure at the manifold 6-55 bar, temperature 20 ° C. At the outlet from the collector 6 of the heated air stream is divided into two symmetrical flow, each of which (0.5 kg / s) is applied to the corresponding standpipe 7, which further divided into three streams, each of which (at 0.167 kg / s) is fed corresponding to the input sections 3 and 4. When the air passes inside the heating element, heat transfer from the heated air occurs downstream of the Joule heat and the temperature at the inlet of the manifold 8 is equal to 680 ° C, the pressure is 50 bar.
Electric current of 1000 A is output to the maximum power for 19 seconds. The process ramp-up device is supplied into the heating elements of its air flow mass flow rate of 1 kg / s of 38 seconds.
Examples 2-4. The method is carried out on the device according to the invention under the conditions of Example 1, but vary the incoming mass flow and pressure at the air inlet flow.
Experimental data relating to Examples 2-4 are given in the table.
Thus, the method of heating the air flow and the device according to the invention possible to carry out a high-temperature and high heat flux at the working pressure at the inlet of less than 20 bar. wherein the pressure loss of the order of 8-10% of the inlet pressure, thus reducing operating costs and energy and are widely used, the invention in industrial conditions in industrial installations.
CLAIM
1. A method for heating a stream of air to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s, the heating element comprising a heating electric current and heat the heated air flow Joule heat, with the heated air stream is passed inside a heating element, wherein that the heated air is supplied to the heating element symmetrical flow directed towards each other and form a common stream of heated air flows through the merge counter, selecting a common heated stream into the space along the center line between the heating elements.
2. A method according to claim 1, characterized in that the heating element of the heating phase is carried out electric current power above 0.3 mW.
3. A method according to claim 1, characterized in that the electric current is output to the maximum capacity in less than 20 seconds.
4. The device for heating the air stream to a temperature above 500 ° C at a mass flow rate above 0.5 kg / s, comprising a three-phase electrical power source, the hollow heating elements, each of which is connected to one phase of three-phase power supply, manifolds for supplying and air outlet to which connected the ends of hollow heating elements, characterized in that the manifold for supplying air is in the form of at least two symmetrical risers, each of which is connected the hollow heating element, and each hollow heating element is divided at least two identical sections disposed along a common longitudinal axis and connected opposite ends to the corresponding standpipe manifold for supplying air, which is the input of each hollow heating element, and the outlet manifold located symmetrically about the riser inlet pipe along the central axis of the device, and the two sections of each heating element is electrically connected in series and electrically isolated from the inlet and outlet manifolds insulators fixed on every floor heating element.
5. The apparatus according to claim 4, characterized in that the insulators are mounted on each floor heating element without clearance.
6. Apparatus according to claim 5, characterized in that each insulator made of a composite fabric material based on silica.
7. Apparatus according to claim 4, characterized in that each hollow heating element made of a metallic conductive material on the basis of stainless steel.
8. The apparatus according to claim 4, characterized in that each hollow member has a length less than 10 m.
9. Apparatus according to claim 4, characterized in that the outer diameter of each hollow heating element ranges from 11 to 20 mm.
10. Apparatus according to claim 4, characterized in that the inner diameter of each hollow heating element ranges from 10 to 18 mm.
11. Apparatus according to claim 4, characterized in that as a source of three-phase electric power source is used than 0.9 MW power and amperage than 1000 A.
12. The apparatus according to claim 4, characterized in that the electric current is output to the maximum capacity in less than 20 seconds.
print version
Publication date 07.12.2006gg
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