RU2314438C1 - Method of continuous delivery of steam or steam-water mixture into water mains and jet water heater for implementing the method - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: method is designed for continuous delivery of steam or steam-water mixture into water mains, and it relates to heater used for implementing the method. Method includes acceleration of liquid in nozzle at reduced pressure, forming of zone of rarefaction, delivery of steam into zone of rarefaction, restoration of pressure of heated water, determination of initial section of jet, formation of additional reverse flow of two-phase steam and water mixture over free surface insulated from main flow by penetrable wall with simultaneous of pressure over free surface and temperature of reverse flow. Heater contains intake chamber, nozzle, and outlet pipe passed through sealed tank. Outlet pipe within the limits of tank has penetrable wall arranged at a distance from nozzle not less than four diameters of nozzle, and ratio of dimensions of manifold to dimensions of pipe is not less than 1.5. Nozzle inlet is connected with tank by pipeline with valve.

EFFECT: increased amount of steam introduced into flow for heating of water.

5 cl, 1 dwg

Description

The invention relates to the field of power engineering and can be applied in any sectors of the economy that have piped water systems and steam sources in operation. In particular, the invention relates to methods and devices for continuously introducing steam into a water stream for heating it to a required temperature range in heat supply systems, hot water supply and water treatment systems to ensure their operability in a wide range of flow rates of heated water and heating steam.

Known inkjet apparatuses for introducing gaseous media and steam into a fluid stream are described, for example, in the book of Sokolov E.Ya., Singer N.M. "Inkjet apparatus". Ed. 2nd, M., "Energy", 1970. The operation of the apparatus is based on the phenomenon of ejection by a flooded stream of a working medium (liquid or gas), a passive medium (also liquid or gas). For example, pages 251-270 describe a mixing jet water heater, the working medium of which is water, and the injected medium is steam, which heats the water during condensation.

Known heater consists of a nozzle, a receiving chamber, a mixing chamber and a diffuser.

The advantage of the analogue is the simplicity of design, as well as the simplicity of manufacture. Its disadvantage is the narrow range of water and steam flow rates at which its stable operation can be ensured. At high steam flow rates, noises, vibrations and hydraulic shocks of pipelines occur due to the collapse of the non-condensing part of the steam. This narrows the operational capabilities of such devices, for example, at peak loads in heat supply systems.

There is a whole class of inventions that improve the operation of inkjet devices, for example, p. 2041404, 2046220, 2061912, 2059893, 2059894, Cl. 6 F04F 5/04; 1809671-1809673, a.s. 1044839, 1806296-1806300, Cl. 5 F04F 5/04; A.S. 901655, Cl. F04F 5/16; A.S. 787736, Cl. F04F 5/20; A.S. 706572, a.s. 787735, Cl. F04F 5/02; A.S. 403880, Cl. F04F 5/04; A.S. 415411, a.s. 442316, a.s. 785558, a.s. 892033, Cl. F04F 5/14; Cl. 2209350, 7 F04F 5/14, Cl. 2125187, Cl. 6 F04F 5/02. But all these devices do not provide continuous input of steam into the water main for heating the current water flow in a wide range of flow rates of steam, water, and diameters of pipeline systems.

The closest technical solution to the claimed is a patent of the Russian Federation No. 2198323, Cl. 7 F04F 5/08, priority June 21, 2000, published February 10, 2003, adopted as a prototype by the method and a prototype by the device.

According to claim 218323, in part of the method, water is accelerated with a decrease in pressure, a rarefaction zone is formed in the pipeline of the water main and a continuous steam supply is carried out into the rarefaction zone. Before the water is dispersed, part of it is taken from the main stream, converted into a dispersed medium, mixed with a steam stream, and the resulting two-phase mixture is fed into the rarefaction zone.

The steam supply device according to claim 218323 consists of a nozzle, a receiving chamber, a preliminary mixing chamber, a steam chamber, a discharge pipe.

The technical solution proposed in the prototype provides a continuous injection of steam into the water main to increase the temperature of the water and utilize the steam without noise and hydraulic shocks at the maximum injection coefficient up to u = 0.06 (u = Gp / Gv, where u is the injection coefficient, Gp is the injection rate steam, Gv - consumption of heated water).

But this solution has a limitation when used in conditions where the steam flow rate increases to values at which the injection coefficient exceeds this limit value (u> 0.06), for example, at peak loads of heat supply systems and hot water supply, as well as in the case of significant fluctuations in water pressure in heating networks.

SUMMARY OF THE INVENTION

The technical problem solved by the claimed invention is to increase the amount of steam introduced into the fluid flow without pressure pulsations, vibration of pipelines and hydraulic shocks, as well as improving performance and increasing the reliability of thermal systems.

The problem is solved in that in the water main, water is accelerated with decreasing pressure, for example, by installing a confuser nozzle, creating a rarefaction zone with a pressure value less than the pressure of the steam source, and continuous supply of steam (steam-water mixture) is carried out in the rarefaction zone. Steam condensation on the water stream and restoration (increase) of the pressure of the heated water stream is carried out in a diffuser or outlet pipe, and the length of the initial section of the water stream flowing from the nozzle is preliminarily determined, and an additional return flow of the two-phase steam mixture is formed downstream of the initial section of the stream and water under a free surface in an extended sealed local zone, isolated from the main stream by a permeable wall. In addition, the gas pressure above the free surface and the temperature of the return flow are simultaneously changed. The length of the initial section of the jet L (the section of the jet between the exit section of the nozzle and the section in which the core of equal velocities is stored) is determined experimentally by measuring the velocity field in different sections of the jet, or using the relations for turbulent jets known from the theory of jets, for example, G.N. Abramovich "Turbulent free jets of liquids and gases." Gosenergoizdat M., 1948, 2nd edition, p. 93.

The essential features of the invention:

- acceleration of the liquid in the nozzle and the creation of a rarefaction zone;

- supply of steam or steam-water mixture to the rarefaction zone;

- restoration of pressure of heated water;

- determination of the length of the initial section of the jet of water;

- the formation downstream of the additional return flow of a two-phase mixture of steam and water under the free surface, isolated from the main water stream by a permeable wall;

- simultaneously change the pressure above the free surface;

- simultaneously change the temperature of the additional return flow.

The signs "acceleration of water in the nozzle with the creation of a rarefaction zone, the supply of steam or steam-water mixture to the rarefaction zone, the restoration of pressure of heated water" are common, the rest are distinctive. The proposed technical solution is illustrated by the structural scheme of the jet water heater, ensuring the implementation of the processes inherent in the proposed method.

The following are indicated on the graphic images:

1 - nozzle

2 - receiving chamber,

3 - outlet pipe

4 - permeable wall of the outlet pipe,

5 - sealed tank,

6 - pipeline with valve,

7 - the initial section of the flooded stream of water,

8 - reverse currents between the wall of the outlet pipe and the outer boundary of the jet of water flowing out of the nozzle,

9 - additional return flow of a two-phase mixture of steam and water,

10 - free surface of the water,

11 - gas-vapor pillow,

12 - the main flow of water.

The device includes a nozzle 1, a receiving chamber 2 of a cylindrical or diffuser shape, a discharge pipe 3 with a permeable section 4 (for example, perforated along the length), passed through an airtight tank 5, a pipeline with a valve 6 for transferring part of the cold water into the tank. The sealed tank may be cylindrical, conical or in the form of a parallelepiped.

The operation of the device is as follows. Water under pressure through the supply line enters the nozzle. In a nozzle made in the form of a confuser or Loval return nozzle, water accelerates to certain speeds and a high-pressure jet is formed at the outlet with a pressure value determined from the Bernoulli integral that is lower than the vapor pressure. The jet structure of the flow is maintained over a considerable length of the discharge line 3 (depending on the speeds of the water stream and steam, it can reach several tens of pipe diameters), while in the space between the stream, the housing of the receiving chamber and the wall of the discharge line, a rarefaction zone is formed with a pressure close to the pressure in a stream that provides input of steam into the water main. With large ratios of the areas of the outlet pipe and the nozzle, reverse currents form along its walls 8. Being carried away by a moving water stream, the reverse currents capture the steam and, forming vortices, turbulence the entire flow, accelerating the condensation of the vapor and the formation of a two-phase foam structure. The axial velocity of the jet of water is maintained in a certain section, called in the theory of jets the initial section of the jet 7, in which there exists a core of equal speeds.

As you move away from the nozzle, the cross section of the core of equal speeds decreases and disappears at a certain distance (L). After the initial section of the jet, a gradual decrease in the flow velocity occurs and the kinetic energy of the jet is inversely converted to potential, accompanied by an increase in water pressure. After the end of the initial section of the jet, part of the stream, including the two-phase, is taken from the main water stream 12 through the permeable wall 4 of the outlet pipe and an additional return flow of the two-phase mixture 9 is formed under the free surface 10 in the sealed tank 5. As the two-phase mixture moves in the tank there is condensation of steam in the additional return flow and the release of bubbles from it through the free surface and condensation on it, that is, the interaction time of steam and water increases, which ensures a guarantee completion of the condensation process. Part of the water selected for the formation of an additional return flow returns through the permeable wall upstream of the main stream due to the positive gradient of water pressure along the length of the outlet pipe. Due to the presence of a vapor-gas cushion 11 above the free surface in the tank, pressure pulsations damp (due to the collapse of the vapor bubbles in the additional return flow 9 and in the main flow 12), and periodic fluctuations in the pressure of the water flow caused by reverse currents 8 are reduced To regulate the damping properties, pressure over the free surface is simultaneously changed, for example, by changing the volume or pressure in the combined-cycle cushion (forcing or evacuating). To accelerate the condensation, the temperature of the additional return water flow is simultaneously changed by transferring part of the cold water from the wide part of the nozzle to the tank through pipeline 6 with a valve. As studies on transparent models showed, an additional return flow is most effective when the ratio of the transverse dimensions of the tank (H) and the outlet pipe (h) is equal to or greater than H / h≥1.5. For a circular jet of water, the length of the initial portion of the jet is taken equal to L = 4-5 nozzle diameters.

The features of the invention are:

- receiving chamber;

- nozzle;

- outlet pipe;

- the discharge pipe is passed through a sealed tank;

- the discharge pipe has a permeable length along the wall within the tank;

- the ratio of the transverse dimensions of the tank and the outlet pipe is at least 1.5;

- the permeable wall is made at a distance of at least four nozzle diameters from its outlet section;

- the nozzle inlet is connected to the tank by a pipeline with a valve.

The signs "receiving chamber, nozzle, outlet pipe" are common, the rest are distinctive. Thus, the proposed method and device have an inventive step, since the combination of features of this method and device determines a new property that gives the required technical effect:

- allows you to increase the amount of steam or steam-water mixture introduced into the water stream to heat it without pulsation of the pressure of the stream, without noise and water hammer;

- allows you to improve performance and increase the reliability of thermal systems and existing jet water heaters, for example:

a) reduce the influence of pressure fluctuations of the consumer network after the heater on its operation, since the pressure is damped in the tank of the proposed heater, not reaching the nozzle and the receiving chamber;

b) when working in a closed system with periodic sharp fluctuations in the pressure of the water in the circuit for several atmospheres (autoclave production, hot water supply, etc.), the sealed tank acts as an accumulating tank, smoothing out the negative effects during the period necessary to recharge the system.

In accordance with the invention, for a water pipeline system with a nominal diameter of 300 mm, with a water flow rate of 400 t / h, an excess working pressure of water of 0.6-0.7 MPa, a vapor pressure of 0.6-0.7 MPa, was made jet water heater. The operation of the heater in real operating conditions allowed to increase steam consumption by 20% compared with the prototype. At the same time, the heater worked stably, without ripples.

Claims (5)

1. A method of continuously supplying steam or a steam-water mixture to a water line, including dispersing water in a nozzle with creating a rarefaction zone, supplying steam or a steam-water mixture to a rarefaction zone, restoring the pressure of heated water, characterized in that the length of the initial section of the water stream is previously determined and lower an additional return flow of the two-phase mixture under the free surface, isolated by a permeable wall from the main water flow, is formed in the stream. 2. The method according to claim 1, characterized in that at the same time change the gas pressure above the free surface. 3. The method according to claim 1, characterized in that the temperature of the additional return flow of water is simultaneously changed. 4. A jet water heater containing a nozzle, a receiving chamber, a discharge pipe, characterized in that the discharge pipe is passed through a sealed tank and has a permeable wall within the tank, while the ratio of the transverse dimensions of the tank and the discharge pipe is at least equal 1.5, and the permeable wall is located at a distance of at least 4 nozzle diameters from its outlet section. 5. The jet water heater according to claim 4, characterized in that the nozzle inlet is connected to the tank through a pipeline with a valve.