RU2151975C1 - Method of making ice on river surface - Google Patents

Abstract

FIELD: hydraulic engineering; hydroelectric stations with deep water intake operated in northern regions. SUBSTANCE: forced cooling of water flow is effected to state of "water - ice". Then compressed atmospheric air cooled to water temperature is fed and is mixed with flow of cooled water, thus forming air-water-ice mixture which is frozen in cold air. Spraying is effected in layer of water. EFFECT: reduction of harmful ecological effects on environment. 3 dwg

Description

The invention relates to hydraulic engineering, in particular for hydroelectric power plants (HPS) with deep water intake, operated in the northern regions. It can be used to reduce the environmental damage caused by this type of hydroelectric power station, namely
the formation in winter of water-ice fog over a long ice-free wormwood in the downstream of hydroelectric facilities, which creates an environmental problem in nearby settlements;
discharge of water from the deep layers of the reservoir, depleted of oxygen.

 Known methods of selective water intake on dams from the reservoir, aimed at reducing environmental damage. These methods are implemented using movable barriers installed in front of the dam and in the reservoir (1).

The disadvantages of this method are: inefficiency due to the capture of large masses of warm water;
the presence of mobile devices that precede the culverts of the hydroelectric power station and are the source of the emergency situation at the hydroelectric station in the event of a device breakdown;
limited ability to control the processes of ice formation in the downstream and, as a result, the possibility of formation of ice jams and floods in spring.

 There is also a method of regulating the temperature of water in the downstream of a hydroelectric power station, aimed at reducing environmental damage, based on the spraying of atmospheric air in the river stream after the dam and creating a lightweight surface layer of water in contact with cold atmospheric air (2).

 The disadvantage of this method is the inefficiency of the reduction of wormwood, caused by the rapid disappearance of the effect of the "light layer", due to the low solubility of air in water, as well as the low heat capacity of air in comparison with the heat capacity of water.

 The closest in technical essence is a method of producing ice on a water surface, including spraying water and exposure to frosty air above the surface (3).

The disadvantage of this method are:
the formation of water-ice fog in the atmosphere and, as a result, environmental degradation in nearby settlements;
The problem solved by the invention is the reduction of harmful environmental impacts on the environment.

 The problem is solved by the fact that they produce ice on the surface of the river, including spraying and exposure to frosty air above the surface of the river. New in the proposed solution is that before spraying, the water stream is forcedly cooled to a state close to the water-ice transition, compressed air is supplied, then mixed with a stream of chilled water, the air-water mixture is sprayed in the thickness of the river stream with the formation of a stream of air-water-ice mixture and freezing this mixture in frosty air. The technical result is a continuous and regulated ice formation on the river due to the resources of hydroelectric power stations.

 In FIG. 1 presents a structural diagram of the implementation of the method.

 In FIG. 2 shows the thermophysical characteristics of the process of water freezing.

 In FIG. 3 shows the dependence of the density of water and ice in the working temperature range.

The method is implemented as follows. Part of the water flow (see Fig. 1) ≅ 1 m ³ / s) after the dam is forcedly cooled (operation 1). The cooling of the water flow is carried out in a powerful refrigeration unit using the resources of the hydroelectric power station - mechanical energy of the water wheel or electrical energy of the generator. The implementation of this operation can be carried out in various types of refrigeration units with mechanical and electrical power supply.

In order to freeze 1 kg of water with a temperature of +4 ^o C, you need:
cool it to a crystallization temperature of 0 ^o C, taking energy equal to 16 kJ;
take 332 kJ to crystallize water, while the temperature remains constant and equal to 0 ^o C.

 Water flow is cooled by contacting it with the cooled working surface of the refrigeration unit to a state close to transition to ice (line A-A, Fig. 2). By selecting the operating point (line AA, Fig. 2), the pre-cooling prevents icing inside the unit. Thus, preparation for freezing and removal of most of the accumulated heat from the water takes place.

At the same time (operation 2), compressed and cooled atmospheric air is supplied. Atmospheric air is compressed to pressures not exceeding the hydrostatic pressure of the hydroelectric power station (8-10 atm), cooled to temperatures close to the temperature of chilled water (about 0 ^o C). This is realized, for example, using stationary-type air-compressor units with electric power supply, forced cooling, adjustable capacity, and net power, which ensures the displacement of the operating point from line AA to the freezing point of 332 kJ (see Fig. 2), t .e. the final freezing of the chilled water stream in step 4.

 Then carry out the displacement of air with a stream of chilled water (operation 3). Air is mixed with highly chilled water by gas-liquid mixers. The degree of homogeneity, as well as the proportion of mixing the cooled and compressed air stream with the stream of highly cooled water, is carried out in such a way as to ensure freezing of water during the subsequent operation 4.

 Then the air-water mixture is sprayed in the thickness of the river stream (step 4) by placing the outlet openings of one or more gas-liquid mixers at depths in the thickness of the river stream. The depth range of the placement of the outlet openings is selected based on the immersion of the outlet openings of the mixers at a low level of water in the river and the elimination of erosion of the bottom by air-water flows escaping from the mixers.

 When spraying the air-water mixture, the air escaping under pressure expands sharply, contributing to the additional cooling of the water flow. Losing its energy, water begins to crystallize, turning into growing ice crystals. The formation of the ice phase. Thus, at the exit of operation 4, a stream of air-water-ice mixture is formed.

Having a lower density, the air-water-ice mixture floats to the surface of the river, forming a non-mixing surface layer bordering on frosty air. From this graph it can be seen that the density of water at 0 ^o C is less than the density of water at +4 ^o C, so cold water does not mix with warm, but remains on the surface of the river in contact with frosty air. The density of ice is much lower than the density of water. The resulting air-water-ice mixture is carried downstream of the river.

 Freezing a layer of air-water-ice mixture in frosty air and the formation of a continuous ice cover on the surface of the river (step 5) is as follows. In the surface layer of the air-water-ice mixture, bordering the frosty air, the processes of crystallization of water and the growth of ice floes moved by the river continue. In places of reduced flow velocity (near the coast, at the edge of the ice), the ice begins to freeze, forming a continuous coating on the surface of the river. Gradually, ice covers the entire wormwood.

1. Calculation of the required cooling power:
The length of the non-freezing part of the Yenisei is 2500 • 10 ³ m
The estimated width of the Yenisei is 1000 m.

The estimated ice layer is 5 • 10 ³ m,
The designed duration of freezing of wormwood is 15 days (15 • 24 • 3600 = 1.296 • 10 ⁶ s.)
Installation capacity on ice (highly chilled water):
Q = 250 • 10 ³ • 1000 • 5 • 10 ^-3 / 1.296 • 10 ⁶ = 0.96 m ³ / s
Power required:
P = Q • ρ • (q • ΔT + q _int = 0.96 • 1.0 • 1000 • (4.212 • 4 + 332) = 335 MW
Conclusion: the required capacity of 335 MW is less than the power of one unit of a hydroelectric power station (500 MW) and significantly less than the installed capacity of a hydroelectric power station - 6000 MW, which allows us to implement the proposed method.

The proposed method provides the following technical results:
1. Reducing the formation of water-ice mists in the atmosphere.

 2. High-performance formation of ice cover on the surface of the river (disappearance of wormwood).

 3. The continuity and adaptability of ice formation.

 4. Environmentally friendly heating of the nearest settlements. The heat released in the refrigeration and compressor units can be used for heating and communal needs of the nearest settlements. Moreover, boiler houses polluting the air can be reduced in these settlements.

 5. Aeration, oxygen enrichment of water discharged by hydroelectric power plants from the deep layers of the reservoir.

 Thus, the proposed method reduces the environmental damage caused by hydroelectric power plants (HPS) with deep water intake, operating in the northern regions.

Sources of information
1. Is it possible to freeze the Yenisei. Collection of materials of a scientific and technical conference. Divnogorsk April 27, 1993. Publishing House of the Krasnoyarsk University, 1994

 2. Copyright certificate of the USSR. A method of regulating the temperature in the downstream of a hydraulic structure. N 1798427, MKI E 02 B 9/04. V.V. Nikitin, A.A. Kagan.

 3. French patent. FR N 2538091 A1, F 25 C 1/00, 22/06/84.

Claims (1)

 A method of producing ice on a river surface, including spraying and exposure to frosty air above the river surface, characterized in that prior to spraying, the water stream is forcedly cooled to a state close to the water-ice transition, compressed and cooled atmospheric air is supplied, then mixing it with a stream of chilled water, spray the air-water mixture in the thickness of the river flow with the formation of a stream of air-water-ice mixture and freezing this mixture on frosty air.

Images