JPH0236635B2 - - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to methods of making artificial snow and ski resorts using such snow.

Description of the Prior Art At several ski resorts around the world,
Artificial ski slopes are created using a variety of different techniques.

One method is to spray atomized water and compressed air (or other gas) into the subfreezing atmosphere;
It is to form artificial snow using a machine that forms a snow blanket. The adiabatic expansion of air absorbs heat from the atomized water, and the particles freeze to form snow flakes. This machine is expensive to install and operate, requires large amounts of compressed air, and requires zero air and ground temperatures to prevent snow from melting.
Skiable snow can only be produced when the temperature is below °C. Despite the large investment and operating costs, such machines are currently in use because they can extend the ski season by a month for some resorts.

A basic method for producing snow using this type of technology was disclosed in US Pat. No. 2,676,471 (Pierce). The method and apparatus for improving this technique are
US Patent No. 3716190 (Lindlof); 3010660
(Barnett); 3301485 (Tropeano); 3298612
(Torrens); 3761020 (Tropeno et al); 3774843
(Rice); 3774842 (Howell); 3945567
(Rambach); 4004732 (Hanson); 4083492
(Dewey); 4105161 (Kircher et al); 3733029
(Eustis et al), and Australian patent application
No.77956/75 (Burnss) and 12534/83
(Albertson).

The atomized water particles are fed into an air stream generated by a fan (e.g., as described in U.S. Pat. No.
3760598 (Jakob et al) and 2968164 (Hanson)
), and the formation of snow flakes or crystals is caused by ice crystals (as shown in U.S. Patent No. 3596476
(see Jakob et al)) and bacteria (see US Pat. No. 4,200,228 (Woerpel)).

To prevent artificial snow from melting, U.S. Patent No.
3893507 (Mac-Cracken et al) and Australian Patent No. 363962 (Michaelis) disclose methods of freezing or cooling earth using refrigeration systems of the type used for skating rinks and in mining. These methods do not overcome the problem of snow flakes melting in the air, and the steady freezing of snow produced by the Pierce method, for example, is difficult when heat from the air above the snow is absorbed through the snow into the refrigeration. , which will eventually turn into an ice porridge unsuitable for skiing.

In warmer regions, artificial ski slopes have been developed using synthetic materials such as pine, bristles, or carpet. Such slopes are sold under the trademarks "Dendex", "Delta" and "Dri-Sno" and are covered by U.S. Patent No. 3400643.
(Holley), 3731923 (Grieve) and Australian Patent Application No. 71499/74 (Snow Products Inc.)
is subject to. These slopes require special skis and poles, and cannot form true snow-covered slopes.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a relatively simple and inexpensive method of producing artificial snow.

A preferred object of the present invention is to provide a method by which snow can be used and maintained at temperatures not previously thought possible.

A further preferred object is to provide a method by which snow can be deposited in layers of various crystal sizes, for example to reproduce powder snow and compacted snow.

A further preferred objective is to provide a method by which snow can be collected, reused or reprocessed as required.

A further preferred object is to create a ski resort containing snow produced by the method of the invention.

Other preferred objects will become apparent from the description below.

In one aspect, the invention comprises: (a) mixing water and a water-swellable polymeric material to form an aqueous gel at or below the maximum water holding capacity of the material; (b) aerating the aqueous gel; c) A method for producing artificial snow, characterized by including a step of freezing an aerated gel to form snowflakes.

Preferably water-swellable materials include all polymers, copolymers and terpolymers that can swell with strong gel strength in aqueous solution. These include polymers and copolymers of acrylamide, acrylic acid, polyacrylates, vinyloxazolidinones, methacrylates, styrene, vinyl ethers and salts of styrene sulfonic acid, as well as polymers and copolymers of cellulose fibers. Suitable polymers include US Pat. No. 3247171 (Walker et al); 3022279
(Proffitt); 3022280 (Shukys), 3251194; UK Patent Application No. 2127005 (Chemical Discoveries AS)
and Australian Patent No. 464077 (The Dow
Chemical Company).

Most preferably, the polymer absorbs about 30 to 100 times its own weight in water to provide good gel strength, minimal evaporation, and reduced permeability.

Preferably, the water-swellable polymer for hard snow is mixed with water at between 30 and 85% of its maximum water holding capacity, preferably between 50 and 70%. This may be, for example, 50 parts water: 1 part polymer (by weight). Preferably for fine powder snow, the polymer has 5 to 50% of its maximum water holding capacity, preferably 5 to 50% of its maximum water holding capacity.
Mixed with water at ~15%. Such mixtures may contain 5 to 15 parts water: 1 part polymer (by weight).

Surfactants can be added to the mixture to reduce the surface tension of the water and generate microbubbles within the snowflake matrix to create a honeycomb effect. Suitable surfactants are soaps and detergents, linear or branched alkylbenzene sulfonates, sulfated aliphatic or aromatic alcohols, alkylene sulfonates, sodium dodecylbenzene sulfonate, alkyl sulfonates, and anionic, cationic and nonionic interfaces. Contains active agent. When using cationic or anionic surfactants, the polymer becomes cationic or anionic and the snowflakes become mutually repellent.

The mixture is sprayed from a nozzle.
Or it can be aerated by mechanical stirring or whisking in the mixing chamber.

The mixture can be frozen at 0° C. or below, and the hardness of the ice increases as the temperature decreases as additional water within each crystal is frozen.
(Snow crystals have been observed to form when about 5% of the water contained within the polymer converts to ice.) The practical minimum temperature is about -20°C.

The snow should be 75-200mm, preferably 125-150mm, to form a ski slope on the frozen floor.
laid to a depth of Preferably, the snow is laid down in several layers in a manner similar to natural snow. The frozen floor may be of the type used for ice skating rink floors; a suitable example is Australian Patent No. 363962.
(Michaelis); US Patent No. 3893507; 3379031;
2878651 and 3751935, and Holmsten Ice Rinks, St. Paul, Minnesota, USA.
Described in “Holmsten Rinkmaster” sold by Inc.

The floor is preferably surrounded by side walls to control the potential for environmental contamination when the snow melts.

The amount of refrigeration tons to keep the snow frozen will depend on the environmental temperature. The surface layer of snow crystals is scraped off the slope, the crystals melt back into the gel, and the foreign material is filtered out before being refrozen and redistributed onto the slope.

In a second aspect, the invention resides in a ski resort that includes artificial snow made by the method described above.

[Brief explanation of drawings]

In order to enable a thorough understanding of the invention, preferred embodiments will now be described with reference to the accompanying drawings.

FIG. 1 is a partially cross-sectional, partially schematic diagram of a ski resort. FIG. 2 is a schematic layout of another snowflake manufacturing facility.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Water-swellable polymers that are mixed with water and frozen to produce snowflakes can be formed, for example, from the following components:

Water 100ml Acrylamide monomer 20ml Tetramethylethylenediamine 1ml 7% ammonium peroxide 4ml Methylenebisacrylamide (0.002-0.005
%) 0-4g Detergent surfactant 10-50ml (optional) These ingredients are mixed well and their own weight is
It is allowed to react exothermically to produce a highly crosslinked polymer matrix that can hold 50-100 times more water. The resulting gel is dried and ground into a powder or formed into flakes or granules.

The manufacture of a ski slope using polyacrylamide powder will now be described with reference to FIG.

Ski slope 10 is constructed on the slope of a mountain or hill to provide downhill skiing.

The slope is surrounded by side walls 11 which control the outflow of the water/polymer mixture when the snowflake melts. This avoids possible damage to the surrounding environment.

A flexible refrigeration pipe 12 is laid in a sand bed 13 on an underground base 14. Refrigeration pipes are connected to respective manifolds 15 which are connected to freezing units 16. Refrigerated liquid from pipe 12, for example brine, passes through heat exchanger 17 and is returned via brine pump 18. Heat from the refrigeration liquid is dissipated by the liquid circulating by pump 20 through heat exchanger 17 and freezing tower 19.

Water from supply tank 21 and supply hopper 22
The polyacrylamide powder from
Mixed to absorb water to 50%.

The resulting gel is pumped through a line 24 into which air is injected by an air compressor 25. From the air compressor, the aerated gel was connected through line 26 to a row of spaced apart nozzles that sprayed the aerated gel onto the frozen floor 28 formed by the frozen pipe 12 and the sand bed 13. Line 26 into manifold 27
sent through.

Since the air above the floor is below 0℃, the water in the polymer particles sprayed from the nozzle begins to freeze, and as soon as 5% of the water freezes, snowflakes are formed, and this water is absorbed into the polymer particles. A frozen shell forms around the absorbed water residue. Since the polymer is highly cross-linked, the pores in the polymer particles are very small, and due to the presence of ice, only a small amount of cross-linking between crystals occurs. A layer of snowflakes is laid at a time about 25 mm thick until the snow is about 125-150 mm thick. The snow in these layers has the characteristics of natural hard snow.

A thin layer of fine powder snow, for example 6 to 12 mm thick, is formed on the surface of the already laid snow. The water-polymer ratio is reduced to 5-15 parts water to 1 part polymer. Due to its high polymer content, snow acts as an insulator against the absorption of heat from the ambient air and CO
The NH ₂ side chain absorbs UV radiation. If it rains,
Polymers can absorb some water without damaging the ski surface.

The test shows that by lowering the temperature to, say, -20°C, the percentage of water absorbed into the freezing polymer increases to, say, 85%, and if the temperature is allowed to rise to, say, -2°C. , showed that the ice in frozen ice shells melts without destroying the snow crystals and regenerating the gel. However, as the temperature decreases, the crystals become harder due to the high ice content.

This phenomenon leads to significant savings in operating costs of the refrigeration unit 16. When the ambient air temperature is low at night, the refrigeration unit can be operated to reduce the snow crystal temperature by, for example, -18°C. High ambient air temperatures during the day heat the crystals, but snow temperatures, such as -
As long as the temperature does not exceed 1.8℃, it will not affect snow. If the ambient temperature becomes relatively high, e.g. 5 to 10 DEG C., the refrigeration unit only needs to be operated for a short period of time to keep the snow temperature below the critical temperature, e.g. -1.8 DEG C. (This critical temperature will depend in part on the particular polymer used.) For example, an insulating cover of plastic material may act as a weather barrier to protect the skier (and reduce heat absorption by the snow from the ambient air. ) supported on a slope.

To preserve the ski surface, scrape away a thin layer and add side drainage grooves 2 along the sides of the slope 10.
You can put it in 9. The snow melts and is drawn through the pipe 30 to the filter unit 31, where foreign matter, such as dust, is removed.
(The highly cross-linked polymer particles have small pore sizes, so very little foreign matter enters the particles.) The now clean gel is returned to the mixing chamber 23 for return to the slope, where it is placed in a fine powder layer. will be sprayed on top of the existing snow. (It will be necessary to maintain the required water/polymer ratio.) By laying the refrigeration pipe 12 as a section down the slope, the length and width of the slope can be varied throughout the year. For example, when summer turns into autumn and the ambient air temperature drops, an additional section of the slope can be provided with artificial snow until winter, and the slope can be for example 400-500 m long. When spring brings warmer environmental temperatures and natural snowfall decreases, additional artificial snow can be created to keep slopes at maximum length and extend the normal ski season by, for example, 30 days. Then, when spring turns to summer, sections of the slope can be closed.

To save costs, melted snow is drained and
The gel can be stored for next season. (If preferred, dry the polymer,
Can be stored in powder form. ) In a modified embodiment of the invention (see FIG. 2), the water and polymer are mixed in the mixing chamber 23 as previously described, but the aerated gel is transferred to the refrigeration unit 34 using liquid nitrogen. It is instantly frozen inside. The resulting snow crystals can then spread onto the slope 10 and form a layer to the desired depth.

It will be readily apparent to those skilled in the art that the specific examples described are illustrative examples only. In particular, by varying the water to polymer ratio within the stated range,
By changing the temperature at which snow is frozen, the characteristics of snow crystals can be changed. This property will also depend on the degree of crosslinking of the polymer, crystal size and the particular polymer used.

Various changes and modifications may be made to the described embodiments without departing from the scope of the claims.

Claims (1)

[Claims] 1 (a) a step of mixing water and a water-swellable polymeric material to form an aqueous gel at a temperature below the maximum water holding capacity of the material; (b) a step of aerating the aqueous gel; ( c) A method for producing artificial snow, comprising the step of freezing an aerated gel to form snowflakes. 2. The method of item 1, wherein the water-swellable polymeric material is a polymer, copolymer or terpolymer that can swell with high gel strength in an aqueous solution. 3 Water-swellable polymeric materials lose approximately their own weight in water.
The second method absorbs 10 to 100 times more. 4 The water-swellable polymer material is acrylamide,
The method of claim 2, comprising polymers and copolymers of acrylic acid, polyacrylates, vinyloxazolidinones, methacrylates, styrene, vinyl ethers, and styrene sulfonates. 5. The method of clause 4, wherein the polymer and copolymer are copolymerized with cellulose fibers. 6. For hard snow, the method of paragraph 1, wherein the water-swellable polymeric material is mixed with water at 30-85% of its maximum water holding capacity. 7 Water-swellable polymeric materials have a maximum water-holding capacity of
The method of paragraph 6, mixed with water at 50-70%. 8. The method of paragraph 1, in which the water-swellable polymeric material is mixed with water at 5-50% of its maximum water-holding capacity for fine powder snow. 9 Water-swellable polymeric materials have a maximum water retention capacity of 5.
The method of paragraph 8, mixed with water at ~15%. 10 Water-swellable polymeric material absorbs 100 times its own weight in water, and for hard snow, the water and water-swellable polymeric material are mixed in a ratio of 50 parts water to 1 part water-swellable polymeric material by weight. The method of the second term. 11 Water-swellable polymeric materials absorb 100 times their own weight in water, and because of the fine snow powder,
The method of clause 2, wherein the water and water-swellable polymeric material are mixed in a ratio of 5 to 15 parts water to 1 part water-swellable polymeric material by weight. 12. The method of paragraph 1, wherein the aqueous gel is mechanically agitated or aerated with compressed air or gas. 13. The method of paragraph 1, wherein the aerated gel is frozen at a temperature range of -20°C to 0°C. 14. The method of clause 4, wherein snow crystals are formed when at least 5% of the water absorbed in the polymer, copolymer and terpolymer converts to ice, and only a few crosslinks occur between each crystal. 15. The method of paragraph 1, wherein a surfactant is added to reduce the surface tension of the water and create microbubbles to create a honeycomb effect within the snow crystal. 16 Surfactants include soaps, detergents, sulfated aliphatic or aromatic alcohols, true-chain or branched alkylbenzene sulfonates, alkylarene sulfonates, sodium dodecylbenzene sulfonate, alkyl sulfonates, and anionic, cationic, and nonionic interfaces. 16. The method of clause 15, comprising an active agent. 17. Snowflakes are sprayed or spread on the frozen floor at a depth of 75 to 200 mm according to the method described in paragraph 1. 18 The method of paragraph 17, in which the frozen bed is sloped.