RU2442935C1 - Method of liquid heating in the vertical static tank with flat bottom the hight of which is over the bottom size - Google Patents

Abstract

FIELD: heat engineering.

SUBSTANCE: invention can be used to heat technological liquids in static tanks. The method has it that the liquid is divided into two parts. One of the parts is located in the tank the bottom of which is heated from the outside with directed infrared light, the sources of which are located steadily under the bottom so that their radiation is perpendicular to the bottom surface. The second part of the liquid is located in the steady pipe parallel to the tank outside which is hydraulically connected to the tank with ends in the upper and lower parts of the tank. This part of liquid is heated inside the pipe by electrode boiler. At this initially the liquid shall be upper than upper connection of the pipe and tank. Moreover, infrared radiators and electrode boiler are connected parallel to power output of automatic "voltage-temperature" regulator. Its power input is connected electrically to industrial network and the control input of the regulator is connected electrically to temperature sensor which is fixed on the outside wall of the tank between the tank liquid stall.

EFFECT: method allows ensuring heating of liquid up to set temperature and maintain this temperature in automatic mode.

1 dwg, 3 dwg

Description

The invention relates to the field of heat engineering, directly to the technology of heating liquid substances inside vertically mounted fixed tanks with a flat bottom, the height of which is significantly larger than the size of the bottom.

The invention can be used for heating process liquids in fixed containers for washing parts, cables and other products after manufacture or before assembly. Heating of solutions (electrolytes) in electrolysis and hydrolysis tanks, in galvanic baths. Heating to a liquid state of thermoplastic materials in containers (for example, bitumen, paraffin, other oil products or polymers). Heating food liquids in pots, tanks, boilers, kettles, that is, in industries such as engineering, instrumentation, chemistry and petrochemistry, electroplating, food processing, medical equipment, household appliances, etc.

1. The prior art

Known methods for heating cylindrical rotating containers from the inside by continuously supplying superheated steam to their internal cavity with simultaneous drainage of condensate [1, 2, 3, 4]. Their main disadvantage is the high energy intensity due to the low heat transfer coefficient between steam and the inner surface during convective heat transfer.

Known methods for heating cylindrical rotating containers from the inside by feeding into their internal cavity combustion products of liquid or gaseous fuels, including by burning gas mixtures inside containers [5, 6, 7, 8, 9, 10]. The main disadvantages: high energy intensity due to the low heat transfer coefficient between the gas and the inner surface of the SC (SB) during convective heat transfer; greater complexity in the implementation due to the need for installation and maintenance of chimneys.

A known method of heating similar containers built-in and rotating transformer [11]. The disadvantages of this method are the low energy intensity due to the large transformer losses of electricity and the complexity of implementation.

Known methods for heating rotating cylindrical tanks from the inside by high-frequency currents [12, 13, 14, 15]. The main disadvantages are excessive energy consumption, complexity of implementation and limited functionality, due to the impossibility of inducing eddy (surface Foucault currents) currents in non-ferrous metal alloys,

Known methods for contact electric heating of the cylindrical wall of a rotating cylindrical tank [16, 17]. The main disadvantages: the difficulty of implementation (manufacturing, installation and replacement of an electric heater) and high energy intensity.

Known methods for heating the cylindrical wall of a rotating container from the inside through directional electromagnetic radiation (EMR) of the infrared spectrum (hereinafter referred to as IRI (infrared radiation) by linear emitters of limited length [18, 19, 20, 21]. The main disadvantages are the difficulty of implementation due to the need manufacture, installation and adjustment of individual reflectors for each individual emitter to create an IKI aimed at the inner cylindrical surface.

There is a method of heating the cylindrical wall of a rotating container from the inside by point sources, compared with the dimensions of the container itself, by sources of directional IKI (NIKI) [22]. These emitters are electric, mirror, infrared incandescent lamps, which are produced by domestic and foreign industry. The inner surface of the bulb of such a lamp is equipped with a mirror reflector directing all the energy of the IRI spiral along the axis of the lamp in the direction opposite to its base. In this method, these lamps, by means of heat-resistant ceramic cartridges, are fixedly mounted on the flat faces of the fixed box, and the box is fixedly mounted inside the container, coaxial to its inner cylindrical surface, so that the NIKI of each point source is directed radially to the inner surface of the container. This method allows to eliminate most of the disadvantages of convective heating, transformer heating and heating by NIKI from linear emitters of limited length.

The disadvantages of this method are the high structural and technological complexity of implementation, the lack of reliability and durability of the electrical system (wiring, cartridges and a large number of electrical contacts) inside the tank, as well as excessive energy consumption.

The main disadvantage of all of the above heating methods is that their implementation does not functionally allow heating the flat bottom of a fixed vertical tank, the height of which is significantly larger than the size of the bottom.

Also known are flow-through electrode boilers ("GALAN") [23], which heat the liquid in its own ionization chamber due to the high-frequency change of the poles of the ionization of the liquid molecules (with an industrial network frequency of 50 Hz).

These boilers are a tubular (cylindrical) ionizer (heater), to which a heating system hydraulic pipe is connected on both sides. Due to high-frequency ionization and reionization (from plus to minus) of the liquid molecules - the latter, in the boiler chamber, heats up quickly, its pressure rises and such a boiler works both as a liquid heater and as a hydraulic pump. Such an electrically powered pump makes it possible to heat a liquid (for example, water) in a flow pipe connected hydraulically to water heaters and to provide centralized water heating, for example, in a room, apartment, or in a building consisting of several rooms.

There is no information on the use of such boilers for heating liquids in a vertically installed fixed tank with a flat bottom, the height of which is greater than the size of the bottom.

2. The closest technical solution (prototype) to the claimed one is a method of heating the flat bottom of the tank adjacent one side to the flat surface of the heater, made in the form of a flat annular heating element [24].

In this method, a flat annular TEN is placed horizontally and motionless in the focal plane of a fixed spherical reflector. On the upper surface (plane) of the heating element, a flat surface of the bottom of the heated container is installed. When a ring heater is connected to the mains, its heating element (spiral) is heated, heating its entire flat body together with the insulating material inside by means of heat conduction. Thermal energy is transferred from the upper plane (surface) of this heater to the container surface adjacent to it by means of heat conduction and thermal conduction over the entire area of their contact (along the surface of a flat ring).

The thermal radiation of the heated lower surface of the annular TENA is reflected by a spherical reflector and is focused by it on the flat surface of the tank in the center of the circular opening of the annular TENA (small circle area). This radiation, in fact, is a high-frequency electromagnetic radiation of a heated surface, since the outer surfaces of the heating elements are heated to 600-700 ° C.

This technical solution can be functionally used to heat the surface of a round flat bottom of a fixed thin-walled cylindrical tank mounted vertically.

The advantages of the prototype over its analogues are compactness, environmental friendliness and the possibility of heating a flat round fixed bottom, as well as the beneficial use of thermal energy of the surface of the annular heating element that does not come in contact with the surface of the bottom.

The main objectives of the invention (in comparison with the prototype) is to obtain the following technical results.

1. Ensuring the heating of the liquid to a predetermined temperature and an increase in the rate of heating of the liquid in the tank,

2. Automation of heating the liquid in the tank and maintaining its set temperature in automatic mode.

3. Reasons that hinder the receipt of technical results.

The main reasons that impede the effective use of the known method (prototype) are the following circumstances. 3.1. The inability to heat the liquid in the tank, the height of which is larger than the bottom to a predetermined temperature and the small (limited) heating rate in the prototype is due, on the one hand, to large losses of energy for heating the bottom of the tank.

The electric energy consumed by a flat ring TEN is spent on heating its spiral (heating element). The thermal energy of the spiral is spent on heating the insulation inside the heater. The thermal energy of the spiral and insulation is consumed through thermal conductivity to heat the housing of the heater.

On one side of the housing of the heating element (above), the thermal energy of the spiral, insulation and the housing is consumed through heat conduction and thermal conduction for heating the flat bottom of the cylindrical tank over the area of its contact with the heating element.

At each stage of transformation (transition) of energy from electrical (from the network) to heat (spiral), thermal (from spiral) to thermal (insulation), from thermal (spiral and insulation) to thermal (body) and further to the bottom, its losses thermal resistance and volume expansion of heating elements. These losses are due to the laws of heat transfer by heat conduction and convection (including thermal conduction) [25].

At the nominal temperature of the outer surface of the heating element 700 ° C (973 K), the specific power of thermal (scattered) radiation is 5 · 10 ⁵ W / cm [26, p.29, Fig. 2-5]. Sources of directional infrared radiation in analogues are incandescent lamps of the type IKZ (infrared mirror) [27], which were declared for heating cylindrical surfaces from the inside, with a nominal coil temperature of 2350 K. They create a specific power of directed infrared radiation of 2 · 10 ⁷ W / cm ² , i.e. 40 times more powerful at the same energy costs.

On the other hand, the dimensions of the heater (TENA), and therefore its power, in the prototype are limited by the dimensions of the bottom of the tank. With a larger height of the tank compared to the size of the bottom (with insufficient power of the heating element due to its limited size) and a large volume of liquid column (liquid mass) in the tank above the bottom, the capacity of the heating element is not enough to heat the liquid in it to a given temperature without using additional heating capacities.

In this case, the heating of the liquid occurs slowly and stops completely after the balance (after reaching equilibrium) of the energies: heating - from the heater and the outside of the tank - due to heat transfer (convection) of the outer surface of the tank with the air surrounding it.

3.2. The inability to heat the liquid to a predetermined temperature, the inability to automate the heating of the liquid in the tank and maintaining its set temperature in automatic mode are due to the lack of these operations in the marked prototype.

4. Signs of the prototype, coinciding with the claimed invention.

In a method of heating a liquid in a vertically mounted fixed container with

a flat bottom, the height of which is greater than the size of the bottom - the bottom of the tank is heated outside.

5. The objectives of the invention are the following technical results.

5.1. Ensuring the heating of the liquid to a predetermined temperature and an increase in the rate of heating of the liquid in the tank.

5.2. Automation of fluid heating in the tank and maintaining its set temperature in automatic mode.

6. These technical results in the inventive method of heating a liquid in a vertically mounted stationary container with a flat bottom, the height of which is greater than the size of the bottom, in which the liquid is heated by heating the bottom interacting with it, are achieved by the fact that the liquid is divided into two parts, one of which is placed in a tank, the bottom of which is heated externally by directional infrared radiation, placing the sources of this radiation motionlessly under the bottom uniformly or unevenly over the bottom so that their radiation is not perpendicular to the surface of the bottom, and the second part of the liquid is placed in a stationary pipe parallel to the tank from the outside, hydraulically connected to the tank by the ends in the lower and upper parts of the tank, as communicating vessels, heating this part of the liquid inside the pipe by means of a flowing electrode boiler, placing it motionless on the pipe above its middle in height, while initially the liquid is poured into the tank above the upper connection of the pipe to the tank. In addition, infrared emitters and an electrode boiler are electrically connected in parallel to the power output of the voltage-temperature autoregulator, the power input of which is electrically connected to the industrial network, and the control input of the regulator is electrically connected to the temperature sensor, which is securely attached to the outer wall of the tank in the middle of the height of the liquid column in the tank.

7. The essence of the invention is illustrated by drawings, where, in Fig.1 shows a diagram of a device that implements the inventive method in longitudinal section, Fig.2 is a diagram of the sources of directional infrared radiation under the flat bottom of the tank (top view), and Fig.3 The scheme of electric power supply of heaters and automatic control of heating is presented.

7.1. A device for implementing the proposed method includes the following structural elements.

1 is a vertical stationary container consisting of a wall 1A and a flat bottom 1B;

2 - stand of the tank 1, firmly attached to the tank 1 from the bottom along the U-shaped contour of the perimeter of the tank 1, outside (for example, welded). The support 2 provides a uniform gap between the outer plane of the bottom 1B of the tank 1 and the surface of the foundation (not shown in the drawings);

3 - emitters of directional infrared radiation, for example, mirror infrared lamps of the type IK3-175 or IK3-250 or IK3-500, for example, manufactured by F "Unitary Enterprise RM" LISMA "(Saransk);

4 - the dielectric base of the emitters 3 (for example, a sheet of PCB), on which the emitters 3 are fixedly fixed by means of electric cartridges (so that their radiation is perpendicular to the plane of the bottom (for example, ICZ lamps with cartridges are mounted on the base 4 perpendicular to the bottom 1B bulb towards the bottom, with a gap between the bottom 1B and the bulb). The base 4 with emitters 3 freely extends and slides along the foundation under the bottom 1B of the tank 1 through a free window (not indicated in the drawings) of the U-shaped contour of the stand 2. The emitters 3 are placed on the base 4 uniform or uneven (figure 2), relative to the surface of the bottom 1 B, in rows;

5 - temperature sensor (for example, thermistor DTV-038), fixedly attached to the wall 1A of the tank 1 from the outside (for example, glued) in the middle of the height of the tank 1;

6 - a stationary pipe welded into the wall 1A parallel to the wall 1A of the tank 1 with the ends 6A from the bottom and the end 6B from the top, hydraulically connecting the upper and lower parts of the inner cavity of the tank 1, forming communicating vessels with the tank 1;

7 - electrode flow boiler, for example, "GALAN", hydraulically connecting the lower 6A and upper 6B sections of the pipe 6 with its internal ionization chamber (cavity). The electrode boiler 7 is installed above the middle of the pipe 6.

In figure 1, 2, 3 and in the text are indicated:

G - liquid inside the tank 1;

UL - the liquid level in the tank 1. The liquid level of the UL is higher than the upper end 6B of the pipe 6;

NPZh1 - heated fluid flow from the bottom 1B, heated by directional infrared radiation from the emitters 3;

NPZh2 - heated fluid flow from the upper end 6B of the pipe 6, heated by a flow-through electrode boiler 7;

ЗЖ - liquid intake by the lower end 6А of the pipe 6 in the process of convective movement of the liquid Ж in the pipe 6;

ARNT - voltage-temperature autoregulator, for example, a thyristor single-phase broadband voltage autoregulator with one control input, with phase current limiting and with a temperature setter;

IKN - infrared heater, consisting of emitters 3 and a flat support 4;

F and N - phase and neutral wire of an industrial electric network;

F1 - phase electric wire from the power output of the ARNT (from the controlled output of the ARNT);

DT - temperature sensor 5, for example DT-038;

R _e is the equivalent electrical resistance of the emitters 3 when they are connected in parallel with F1 and N;

R _e and flow electrode boiler 7 are connected to the controlled output of the ART

(F1, N) in parallel (figure 3).

7.2. Declared as the invention, the heating method is implemented as follows.

Before starting to heat the liquid Ж inside the tank 1 (Fig. 1), pour the liquid Ж (for example, water) inside the tank 1 to the level of the core, above the hole of the upper end 6B of the pipe 6. At the same time, the temperature sensor 5 (DT) is electrically connected (connected) ) to the control input of the ARNT controller (Fig. 3), and the infrared heater 3, 4 and the flow-through electrode boiler 7 are connected in parallel to the controlled power output of the ARNT (not indicated in the drawings). Next, the ARNT is connected to a power electric network, the setpoint temperature (ARNT) sets the desired (required) temperature of the liquid W in the tank 1 and the operating voltage from the ARNT output is applied simultaneously to the infrared heater TCR (R _e ). The TSC heats the bottom 1B of the tank 1 from the outside by heat transfer by radiation, the inner surface of the bottom 1B is heated from the outside by thermal conductivity of the wall of the bottom 1B, and the liquid W is heated in contact with the inner surface of the bottom 1B and thermal conductivity, and conduction, and convection, while the liquid heated near the bottom Ж forms a convective upward flow (heated liquid flow 1), which cools as it rises, mixing with layers of unheated liquid Ж.

At the same time, the liquid G inside the ionization chamber of the flow-through electrode boiler 7, which is also the internal cavity of the pipe 6, is heated. When heated, it rushes up inside the pipe 6 due to convection. The increase in pressure due to heating W inside the ionization chamber increases the speed (accelerates) the flow of heated liquid W upward, inside the pipe 6. The speed of the heated liquid flow of the NSP 2 from the upper end 6B of the pipe 6 is continuously accelerated, and the temperature of the NPS 2 flow is higher than the temperature of the NPS flow 1 since the intake of coolant liquid by the lower end 6A of the pipe 6 is carried out with a higher temperature than the temperature of the liquid J. The increase in the flow rate of the fluid 2 occurs until the temperature of the liquid in the tank 1 reaches a predetermined one.

When the set temperature of the liquid F is reached, the signal from the temperature sensor (DT) 5 through the control input of the ARNT reduces the voltage in the power controlled output of the ARNT, reducing the supply voltage of the ICH (3, 4) and the flow electrode boiler 7, while maintaining the set temperature of the liquid Zh and keeping constant the voltage value in the power controlled output of the ARNT corresponding to a given temperature. Until the set temperature is reached, both the infrared heater TSC and the flow-through electrode boiler operate in the nominal mode, at the rated electric voltage (for example, 220 V), with the rated power.

7.3. Positive results.

The first positive result of the invention, namely, providing heating of the liquid to a predetermined temperature and increasing the rate of heating of the liquid in the tank is ensured by the fact that

1) The temperature of the liquid is set and monitored continuously by the temperature setter of the ARNT autoregulator by means of a temperature sensor (DT) 5, which is constantly connected to the outer surface of the wall 1A of the tank 1 with the heated liquid Zh at the middle of the height of the tank 1 outside (Figs. 1, 3).

2) Significantly increases the thermal power acting on the liquid Ж inside the tank 1 without increasing the area occupied by the tank 1, since it is created by the heated bottom 1B inside the tank 1 and, at the same time, inside the pipe 6 filled with the liquid Ж, as in a hydraulically communicating vessel with capacity 1, through an electrode flow-through boiler (for example, "Galan"). Therefore, the liquid G in the tank 1 heats up at least two times faster than in the prototype (with the same electric power infrared heater under the bottom 1B and the electrode flow boiler).

3) The specific power of the directional infrared radiation of each emitter 3 is 40 times greater than the specific power of the heating element in the prototype

The second positive result of the invention, namely, the automation of heating the liquid in the tank and maintaining its set temperature in automatic mode, is ensured by the fact that

1) The heating of the liquid W in the tank 1 is carried out by supplying electrical power to the IKN (3, 4) and the electrode flowing boiler 7 from the controlled power output of the AVTNT voltage-temperature autoregulator, to which they are connected in the form of a load as parallel electrical resistances. Since the control input of the ARNT is connected to a temperature sensor (ДТ) 5 and has a temperature setter, so far the heating (voltage value from the power output of the ARNT) always corresponds to the current values of the liquid temperature Zh. When the set temperature of the liquid Zh is reached, its value is automatically maintained constant and the corresponding voltage value from a controlled power output ARNT (figure 3).

2) IKN (Ra) and electrode flow boiler 7 are connected in parallel to the controlled power output of the ARNT. In this case, any automatic change in the output voltage in this output provides, at the same time, an automatic change in the electric power supplied to the TSC and boiler 7, proportional to the intrinsic electrical resistance of the TSC and boiler 7 (Fig. 3). An additional positive result of the invention, namely, the expansion of functionality, is provided due to the fact that

1) Emitters of directional infrared radiation of type 3 ICZ, with relatively the same dimensions, have different nominal electrical power. For example, the infrared reflector lamp IK3-175 has a rated power of 175 W, IK3-250 - 250 W, and IK3-500 - 500 W. Therefore, when placing on the base 4 under the bottom 1B, for example, 42 radiators 3 (Fig. 3), the power of the infrared heater under the bottom 1B, with the radiators 3 connected in parallel, can be 7.35 kW and 10.5 kW, and 21 kW. With different configurations, it is possible to set the rated power of the ICH for heating the bottom 1B from 7.35 to 21 kW and for the same working area of the tank 1 (bottom 1B), to heat more than 2 times large volumes of liquid W inside the tank 1 by increasing the height of the tank one.

2) Electrode flowing boilers, for example, “Galan” [23], with relatively the same dimensions, have different nominal electrical powers, from 2 to 25 kW. Therefore, with different configurations, it is possible to increase the heating rate of the liquid W in the tank 1 by at least 8 times, due to the increase in the heating rate and the flow rate of the liquid W inside the pipe, by changing the diameter of the pipe 6, without increasing the dimensions of the tank 1.

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Claims (1)

A method of heating a liquid in a vertically mounted stationary container with a flat bottom, the height of which is larger than the size of the bottom, in which the liquid is heated by heating the bottom interacting with it, characterized in that the liquid is divided into two parts, one of which is placed in a tank, the bottom of which is heated outside directional infrared radiation, placing the sources of this radiation motionlessly under the bottom uniformly or unevenly over the bottom area so that their radiation is perpendicular to the bottom surface, and the second part of the liquid is placed in a stationary pipe parallel to the vessel from the outside, hydraulically connected to the vessel by the ends in the lower and upper parts of the vessel as communicating vessels, heating this part of the liquid inside the pipe by means of an electrode boiler, placing it motionless on the pipe above its mid-height, initially liquid is poured into the tank above the upper pipe connection with the tank, in addition, infrared emitters and an electrode boiler are electrically connected in parallel to the power output of the autoregulator "voltage s-temperature ", the power input of which is electrically connected to a commercial power supply, and the control input of the regulator is electrically connected to a temperature sensor which is securely attached to the outer wall of the container in the middle of the height of the liquid column in the container.

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