JPS6391470A - Production unit for frozen grain - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus for producing frozen particles such as ice particles that can be suitably used as abrasive particles, abrasive materials, etc. for surface treatments such as blasting and cleaning. It is related to.

(Prior art) As a conventional frozen grain production device, for example,
The one disclosed in No. 392 is known.

This device, as shown in FIG.
A raw material spray nozzle 3 is provided in the second part, annular refrigerant jet pipes 4 and 5 are provided below the nozzle 3 along the inner wall surface of the container, and a scraper 6 is provided at the bottom of the container. Therefore, when a refrigerant such as liquid nitrogen is ejected from the ejection pipe 4.5 toward the inside of the container and a liquid raw material such as water is sprayed downward from the nozzle 3, the sprayed particles 2a of the raw material are Heat is exchanged with the jetted refrigerant and its evaporated gas through cross-flow contact, counter-current contact, or co-current contact, and the refrigerant is frozen. The frozen particles 2b are deposited on the bottom of the container, and the scraper 6
7 In such a device, when the temperature of the cold gas phase in the container 1 becomes below a certain temperature (for example, below -60°C when liquid nitrogen is used as the refrigerant) due to the evaporated gas of the ejected refrigerant, There is a risk that the refrigerant jetted out from the jetting pipes 4 and 5 will not evaporate and fall to the bottom of the container as a liquid. In order to avoid such a situation, as shown in Fig. 9, it is necessary to move the ejection pipes 4 and 5 close to the nozzle 3 so that the temperature of the cold gas phase in the refrigerant ejection area does not fall below a certain temperature. .

That is, the spray particles 2a pass through the refrigerant ejection area immediately after being sprayed, and the evaporation of the ejected refrigerant is promoted by heat exchange with the spray particles 2a.

(Problem to be Solved by the Invention) However, if the spray particles 2a are brought into contact with the jetted refrigerant immediately after being sprayed, the spray particles 2a collide with the jetted refrigerant before becoming spherical due to their surface tension. Therefore, uniform spherical frozen particles 2b cannot be obtained. For example, it is only possible to obtain frozen particles 2b with a distorted shape such as an oval shape, and there is a risk that the sprayed particles will stick together due to collision with the ejected refrigerant and be frozen as they are, and frozen particles of uniform particle size may be obtained. I can't get 2b. Needless to say, such frozen particles 2b are extremely unsuitable as abrasive grains, polishing materials, etc. for blasting, cleaning, etc.

In view of the above, an object of the present invention is to provide a frozen grain production apparatus that can reliably produce frozen grains having a uniform particle size and having a spherical shape.

(Means for Solving the Problems) The frozen grain production apparatus of the present invention has a frozen grain recovery means equipped with a net-like body that partitions the inside of the frozen grain production container into a cold gas phase region and a lower refrigerant evaporation gas generation region. , a refrigerant evaporative gas generating means for generating evaporative gas of a refrigerant such as liquid nitrogen in a refrigerant evaporative gas generating region, and a refrigerant evaporative gas generating means for generating evaporative gas of a refrigerant such as liquid nitrogen, and a refrigerant evaporative gas generating means for generating evaporative gas of a refrigerant such as liquid nitrogen into a cold gas phase from a liquid material to be frozen such as water at a position near a cold air discharge port provided at the upper part of the cold gas phase region. atomizing means for atomizing the region in the cold gas phase region.

By bringing the evaporated refrigerant gas, which passes through the mesh body and rises toward the cold air outlet, into contact with the spray particles of the material to be frozen and causes heat exchange, the spray particles are frozen before they fall onto the network body. It is oval.

(Operation) Refrigerant evaporative gas passes through the reticulated body from the refrigerant evaporative gas generation region to reach the cold gas phase region, and rises through the region toward the cold air outlet. At this time, the refrigerant evaporated gas gradually rises toward the cold air outlet while generating a density difference by sequentially exchanging heat with the sprayed particles of the raw material to be frozen.

On the other hand, the sprayed particles of the raw material to be frozen naturally fall through the cold gas phase region, during which they come into countercurrent contact with the rising evaporated refrigerant gas, gradually undergo heat exchange, and are frozen. In this way, since the sprayed particles are frozen in the presence of only the refrigerant evaporation gas, their spherical formation due to surface tension is not prevented and they become spherical frozen particles.

In addition, since the spray particles only come into contact with the gradually rising evaporated refrigerant gas, the spray particles do not stick together, and each spray particle freezes in a dispersed state, giving frozen particles of uniform particle size. .

Then, the frozen particles fall onto the net-like body and are collected by the frozen particle collecting means. Since evaporated refrigerant gas passes through the net-like body from below, the frozen grains that reach the net-like body are kept cool by the evaporated refrigerant gas and are affected by its flow, causing the hardness of the frozen grains to decrease or freeze upon collection. Inconveniences such as fusion of grains do not occur.

(Example) Hereinafter, the structure of the present invention will be specifically explained based on the example shown in FIGS. 1 to 7.

In the frozen grain production apparatus shown in FIG. 1, 11 is a frozen grain production container, 12 is a frozen grain recovery means, 13 is a spraying means, and 14
is a refrigerant evaporative gas generating means.

The frozen grain production container 11 has a cold air outlet 11 at the upper end of the peripheral wall.
It was constructed as an insulated closed container with a square cross-sectional shape (-side length 400 mm).

The frozen grain collecting means 12 includes a pyramid-shaped network body 15 that narrows downward, and a frozen grain extraction pipe 16 that is vertically disposed at the center of the network body 15 at its lowermost end. The mesh body 15 is attached to the inner peripheral wall of the container 11, and divides the inside of the container 11 into an upper cold gas phase region 17a and a lower refrigerant evaporative gas generation region 17b. As a constituent material of the mesh body 15, a wire mesh (for example, a 5US304 mesh of 150 mesh) or the like is used, which has low temperature resistance and has a mesh degree that allows only the evaporated gas of the refrigerant to pass through. The lower end of the take-out pipe 16 penetrates the bottom wall of the container and
A frozen particle removal valve such as a rotary valve that is led outside 1
6a is provided. The inclination angle θ of the mesh body 15 with respect to the horizontal plane may be set depending on conditions such as the evaporation amount of refrigerant evaporation gas and the frozen particle size, and whether or not a scraper is used. The angle may be selected to be about 45°.

The squirting means 13 includes a sprayer 18 at the center of the earthen wall of the container 11.
and a raw material supply pipe 19 for supplying a liquid material to be frozen, such as water, to the sprayer 18, and a spray gas introduction pipe 2 for introducing a suitably pressurized and cooled spray gas such as nitrogen gas.
0 is connected, and water, which is the raw material to be frozen, is sprayed downward in the form of a mist from the nozzle 18a at the tip of the sprayer 18 by the pressure of the spray gas. Water droplets 24a which are the spray particles
The size can be adjusted as appropriate by the nozzle diameter and spray pressure. In addition to water, various liquids can be used as the raw material to be frozen, provided that they are frozen by heat exchange with the refrigerant evaporation gas.

The refrigerant evaporative gas generation means 14 includes a refrigerant evaporative gas generation region 1
A predetermined amount of refrigerant, such as liquid nitrogen 22, is supplied from the refrigerant supply pipe 21 to the refrigerant 7b, and a bubbling pipe 23 is inserted into the refrigerant 22.
By injecting bubbling gas such as nitrogen gas, argon gas, or dry smelt gas from the refrigerant evaporated gas 22a,
In the frozen particle manufacturing apparatus configured to generate 17a
is raised toward the cold air outlet 11a. That is, the refrigerant evaporated gas 22a gradually rises toward the cold air outlet 11a while generating a density difference by successively exchanging heat with the sprayed particles of the raw material to be frozen, that is, the mist-like water droplets 24a. On the other hand, water i1! 24a naturally falls through the cold gas phase region 17a,
During this period, the ice grains 24b come into countercurrent contact with the rising refrigerant evaporated gas 22a, gradually proceeding with heat exchange, and are frozen. , falls onto the net-like body 15, but
It is collected without accumulating on the net-like body 15.

By the way, when the inventor conducted an experiment using the above device, the amount of water sprayed from the nozzle 18a was determined to be 0.2Q/+ain.
(12Q/h), the average cold gas phase temperature in the lower part of the cold gas phase region 17a, that is, in the upper vicinity region of the mesh body 15, is 180° C. or less in the water spray state, and the sprayed water W424a If the diameter is 300μm or less and the water spray pressure is 4Kg/cm2 or less, the cold gas phase region 17
It has been found that ice grains 24b of sufficiently high quality can be obtained even if the effective height of a, that is, the height H from the nozzle 18a to the net-like body 15, is reduced to only about 1 m. The cold gas phase temperature is closely related to the amount of refrigerant evaporation gas 22a generated, and the water spray state of 0.2 Ω/min (since the cross-sectional area of the cold gas phase region 17a is 0.16 m2, the area load is 7
5Kg/m2・h, cold air load is 25ONm3/m
2.h), the amount of evaporative gas generated from liquid nitrogen 22 is 2ONm3/h, 4ONm'/h, 6ONm''/h.
The temperature distribution in the cross section of the cold gas phase region 17a is as shown in FIG. Therefore, the cross-sectional area of the gas phase is 0.16 m2, and the amount of water spray is 0.2 Q/min (1
2Q/h), when the water spray particle size is 300 μm or less, the refrigerant gas generation rate needs to be 4ONm3/h or more in order to keep the average cold gas phase temperature below -80°C. In this case, the distance the water spray fell was about 1 m, which was necessary to allow enough cooling time to turn the water spray into finely frozen particles.

Since it is possible to reduce the effective height H of the cold gas phase region 17a to about 1 m in this way, the frozen grain production container 11 and the frozen grain production apparatus can be drastically downsized. Note that when the spray pressure is low or when the spray particle size and therefore the frozen particle size are small, the spraying direction of the raw material to be frozen may be directed downward as in the above example; however, when the spray pressure is high or the frozen particle size is small, If the diameter is large,
Since it is necessary to ensure sufficient contact time between the spray particles 24a and the refrigerant evaporated gas 22a, if the spray direction by the nozzle 18a is directed downward as shown in FIG. 1, the container 11 will have to be made larger. Therefore, in such a case, if the ejecting direction is set horizontally as shown in FIG. 4, the contact time between the spray particles 24a and the refrigerant evaporated gas 22a will be sufficient without increasing the size of the container 11. This is convenient because it can be secured at any time.

The ice particles 24b that have reached the net-like body 1S are caused by the fact that the net-like body 15 is sloped downward and the refrigerant evaporated gas 22a is
, it flows over the net-like body 15 along its slope and is collected into the take-out tube 16 . The collected ice grains 24b can be taken out of the container 11 by operating the take-out valve 16a, and are used for blasting or the like. The conditions for turning sprayed water droplets into frozen particles include the amount of water sprayed, the temperature of the cooling gas phase to form frozen particles, the amount of refrigerant gas generated necessary to keep the gas phase temperature constant2 particle diameter, and the drop of frozen particles. It is necessary to consider the speed and contact time of frozen particles with cold air,
Those skilled in the art can appropriately determine these through experiments.

By the way, the quality of collecting the ice grains 24b into the extraction pipe 16 is as follows.
The inclination angle θ of the mesh body 15 on the steel body 15.

Temperature, refrigerant evaporation gas 22a passage speed through the mesh, ice particles 24
Although it is related to the particle size of b, regardless of these conditions, the net-like body 15 is continuously or intermittently subjected to moderate vibration or rocking by a vibration, rocking, or shaking device (not shown) such as a vibrator. Or, if you apply shaking, 2 ice particles
4b can be efficiently recovered into the take-out pipe 16.

As shown in FIG. 2, FIG. 3, or FIGS. 5 to 7, such frozen grain collecting means 12 collects produced ice grains 2
4b may be configured to be directly supplied to the frozen particle injector 25 outside the container 11.

That is, in the frozen grain recovery means 12 shown in FIG.
A frozen grain injector 25 is attached to the lower wall of the frozen grain injector 25, and a frozen grain extraction pipe 16 and a drive gas introduction pipe 27 are connected to the frozen grain injector 25.
When a drive gas such as air or nitrogen gas pressurized to an appropriate pressure is introduced into the injector 25 from the introduction pipe 27, an ejector effect is caused by the action of this drive gas.

The structure is such that the frozen particles 24b are sucked into the injector 25 through the extraction g1.6, and are injected onto the object 28 to be treated to perform surface treatment thereon. A portion 29 of the introduction pipe 27 inside the exhaust heat recovery chamber 26 is a type of heat source that cools the drive gas by exchanging heat with the refrigerant evaporative gas 22a brought into the exhaust heat recovery chamber 26 from the cold air outlet 11a. It is configured in an exchanger. That is, the introduction pipe section 29 serving as the heat exchanger is arranged in a meandering manner to increase the contact area with the refrigerant evaporated gas 22a, and has a large number of fins 29a protruding from the outer periphery as shown in FIG. Constructed into a thick-walled tube,
The aim is to increase the heat transfer area and improve the heat storage effect. A suitable material for the introduction pipe portion 29 is a copper alloy or the like having high thermal conductivity.

By doing so, the drive gas can be sufficiently cooled without providing a dedicated cooling means for the drive gas, preventing a decrease in the hardness of the frozen particles 24b to be injected or fusion of the frozen particles 24b, etc., and blasting. , cleaning, etc. can be performed well. Furthermore, by configuring the introduction pipe portion 29 as a thick-walled pipe with fins 29a, even when the refrigerant evaporative gas 22a is not generated in the case of intermittent operation of the frozen particle manufacturing apparatus, the drive gas is cooling can be ensured. Note that with the above configuration, it is possible to cool the drive gas to a temperature close to the temperature of the refrigerant evaporative gas 22a discharged from the cold air outlet 11,a, but if it is necessary to cool it to a temperature lower than that, For example, a refrigerant such as liquid nitrogen may be sprayed into the introduction pipe portion 29 from a refrigerant spray nozzle 30 provided at the upper part of the exhaust heat recovery chamber 26.

Moreover, the net-like body 15 was not stretched in an inclined manner as shown in FIGS. 1, 2, and 4, but was stretched horizontally as shown in FIG. The frozen grains 24a are moved forward and backward on the net-like body 15 by a cylinder 31 or the like, and are collected in a frozen grain recovery chamber 3 connected to the container 11 by a wetted scraper 32.
Alternatively, the liquid may be collected in the hopper part 33a of No. 3. The frozen grains 24b collected in the hopper part 33a are transferred to the introduction pipe 27
By introducing the drive gas, the frozen grain supply pipe 34
The liquid is sucked into the injector 25 through the injector 25 and is injected onto the object to be treated 28 .

Further, the frozen grain collecting means 12 may be configured so that the inner part of the reticulated body can be moved out of the container 11. For example, as shown in No. 6, a conveyor 3 is provided with an endless mesh belt 15' which is a mesh body and is driven to rotate in the direction of the arrow.
5 divides the inside of the container 11 into upper and lower two-headed regions 17a and 17b, and guides the conveyance terminal end of the conveyor 35 to the frozen grain collection chamber 33 to separate the inside of the container of the mesh belt 15'.
The accumulated frozen grains 24b are collected from the conveyance terminal end of the conveyor 35 to a part of the hopper 33a of the frozen grain collection chamber 33. Further, as shown in FIG. 7, by horizontally rotating the rotary disk 15', which is a net-like body, by an appropriate drive mechanism 36, the frozen particles 24b accumulated on the inner part of the container of the rotary disk 15' are transferred to the frozen particle collection chamber 33. (Effects of the Invention) The frozen grain manufacturing apparatus of the present invention is capable of producing sprayed particles of a liquid raw material to be frozen only from refrigerant evaporation gas. Because it is configured to freeze by heat exchange with the cold air in the cold air phase,
Unlike conventional devices, the collision effect of the ejected liquid particles of the refrigerant does not impede the spherical change and dispersion of the sprayed particles due to the surface tension, making it ideal for use as abrasive grains and abrasive materials for blasting, cleaning, etc. It is possible to reliably produce frozen particles having a spherical shape and a uniform particle size. Furthermore, since the frozen particles accumulated on the net are kept cool and made to flow by the refrigerant evaporation gas passing upward through the net, production of frozen particles can be prevented by reducing the hardness of the frozen particles or by causing the frozen particles to melt together. This can be done successfully without causing any inconveniences such as staining.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical side view showing an embodiment of the frozen grain manufacturing device according to the present invention, FIG. 2 is a schematic vertical side view showing a modification of the same device, and FIG. 3 is an enlarged view of the main parts thereof. 4 to 7 are schematic longitudinal sectional side views showing other modifications of the same device, and FIG. 8 shows the temperature distribution of the cold gas phase in the cold air layer region and the refrigerant evaporation gas in the refrigerant evaporation gas generation region. FIG. 9 is a graph showing the relationship between the generation amount of 11...Frozen grain production container, lla...Cold air outlet, 12...Frozen grain collection means, ]3...Spraying means. 14... Refrigerant evaporative gas generating means, 15H15' 4
15'... Reticular body, 16... Frozen grain removal tube, 1
7a... Cold gas phase region, 17b... Refrigerant evaporation gas generation region, 18... Sprayer, 21... Refrigerant supply pipe, 22... Refrigerant, 22a... Refrigerant evaporation gas,
23... Bubbling pipe, 24a... Sprayed particles of raw material to be frozen, 24b... Frozen particles, 25... Frozen particle injector, 26... Exhaust heat recovery chamber, 27... ...Drive gas introduction pipe. 28...Object to be treated, 29...Introduction pipe portion (heat exchanger), 30...Refrigerant injection nozzle, 32...
Scraper, 33... Frozen grain collection chamber, 33a...
・Part of hopper, 34... Frozen grain supply pipe, 35...
・Conveyor, 37...Scraper device. Patent applicant: Taiyo Sanso Co., Ltd. [Figure 1 Figure 2 Figure 113 Figure 4 @ Figure 5 Figure 6 Figure 7 Figure 9 O

Claims (5)

[Claims] (1) Frozen grain recovery means equipped with a net-like body that divides the inside of the frozen grain production container into a cold gas phase region and a lower refrigerant evaporative gas generation region; In the cold gas phase region, a refrigerant evaporative gas generating means is provided, and a spraying means is provided for spraying a liquid material to be frozen, such as water, into the cold gas phase region at a position near a cold air outlet provided at the upper part of the cold gas phase region. By bringing the evaporated refrigerant gas, which passes through the mesh body and rises toward the cold air outlet, into contact with the spray particles of the material to be frozen and causes heat exchange, the spray particles are frozen before they fall onto the network body. A frozen grain production device characterized by the following configurations. (2) The frozen grain collection means comprises the net-like body made of a wire mesh or the like that slopes downward, and a frozen grain extraction pipe connected to the lowest part of the net-like body. Frozen grain manufacturing equipment as described in Scope 1. (3) The frozen grain manufacturing apparatus according to claim 2, wherein the frozen grain collecting means includes a device that applies vibration, rocking, or shaking to the net-like body. (4) Frozen grain production according to claim 1, wherein the frozen grain recovery means is configured to be able to move the inner part of the reticulated body to the outside of the frozen grain production container. Device. (5) The refrigerant evaporative gas generation means is configured to generate refrigerant evaporative gas by injecting nitrogen gas, argon gas, or dry air into the liquid nitrogen contained in the refrigerant evaporative gas generation region. A frozen grain production apparatus according to claim 1, 2, 3, or 4.