JP4734406B2 - Method for removing ice from ice-containing material using liquefied material - Google Patents

Description

  The present invention relates to a method for removing ice from an ice-containing substance using a liquefied material, and more specifically, it can efficiently remove ice at an operating temperature close to the outside air temperature and with a small amount of required power, and also the ice content and type. The present invention relates to an ice removal method and an ice removal system that can be applied to ice-containing materials in a wide range of fields.

  As a method for removing the ice contained in the substance, a method such as heating and wiping or freeze-drying can be considered, and in the case of ice on the substance surface, a method of physically destroying it can be considered.

  However, in the above-described method, manpower is required and there is a risk of damaging the substance. In addition, some substances are difficult to heat, and in such cases, freeze-drying is used. However, freeze-drying sublimes ice by reducing the pressure, which requires a lot of energy and costs. For this reason, it is limited to the production of high-value-added objects such as pharmaceuticals, foods, and high porosity porous bodies, and it has been extremely difficult to remove ice.

  The present invention has been made in view of such conventional problems, and can be applied to various ice-containing materials regardless of the form and content of ice contained, and can remove ice in a short time. An object of the present invention is to provide an ice removal method and an ice removal system that can be efficiently performed with a recovery rate.

  As a result of intensive studies to achieve the above object, the present inventors have used a liquefaction and vaporization phenomenon of a liquefied substance of a substance that is a gas under normal temperature and normal pressure conditions to remove a piece of wood from a frozen piece of wood. The present inventors have found that it is possible to recover only ice with high efficiency without being damaged, and have confirmed that the present invention can be applied to various kinds of ice-containing substances, and have reached the present invention.

The present invention provides the following inventions.
[1] A step of bringing a liquefied substance of a substance that is a gas under normal temperature and normal pressure conditions into contact with an ice-containing substance, and dissolving ice in the ice-containing substance in the liquefied substance to obtain a liquefied substance having a high water content ( 1) and a liquefied product comprising the step (2) of separating the gas as a gas by evaporating a gas substance under normal temperature and normal pressure conditions in the hydrated product containing a high amount of water. A method for removing ice from an ice-containing material used.
[2] The method further includes a step (3) of recovering a gas of a substance that is vaporized and separated in the step (2) under normal temperature and normal pressure conditions, and liquefying the gas to obtain a liquefied product, The method of removing ice as described in [1] above, wherein the liquefied product obtained in the step (3) is used again in the step (1).
[3] The method for removing ice as described in [1] or [2] above, wherein the substance that is gaseous at normal temperature and pressure is a substance that is gaseous at 25 ° C. and 1 atm.
[4] The above-mentioned [1], wherein the substance that is a gas at normal temperature and pressure is one or a mixture of two or more selected from dimethyl ether, ethyl methyl ether, formaldehyde, ketene, and acetaldehyde -The ice removal method as described in any one of [3].
[5] The ice removing method according to any one of the above [1] to [4], wherein the ice-containing substance is coal, food, porous material, organism, biomass material, or pharmaceutical compound. .
[6] The contact according to any one of [1] to [5], wherein the contact in the step (1) is performed such that the liquefied product and the ice-containing material are brought into countercurrent contact. Ice removal method.
[7] The amount of the liquefied product brought into contact with the ice-containing material in the step (1) is from 0.1 L / kg to 1000 L / kg per amount of water converted to ice contained in the ice-containing material. The ice removing method according to any one of [1] to [6].
[8] The ice removing method according to any one of [1] to [7], wherein the series of ice removing operations is performed in a temperature range of −50 ° C. to 25 ° C.
[9] A substance obtained by removing ice obtained by the ice removing method according to any one of [1] to [8].
[10] A compressor that pressurizes a gaseous substance under normal temperature and normal pressure conditions, a condenser that condenses the pressurized gas into a liquefied product, and contacts the liquefied product with an ice-containing material. A dehydrator that dissolves ice in the ice-containing material to form a liquefied product with a high moisture content, and an evaporator that vaporizes the gaseous material under normal temperature and normal pressure conditions in the liquefied product with a high moisture content. An ice removing system for an ice-containing material, wherein a separator for separating the vaporized gas and moisture of the material is connected in series.
[11] The ice removal system according to [10], wherein the condenser and the evaporator are connected by a heat exchanger.
[12] Further, an expander that expands the gas of the gas substance under the condition of the vaporized normal temperature and normal pressure is connected in series to the compressor, and the work to be performed to the outside of the expander is recovered. The ice removing system according to [10] or [11], wherein the work is input as a part of power of the compressor.
[13] The compressor, the condenser, the dehydrator, the evaporator, and the expander form a circuit, and the circuit is configured to circulate a gaseous substance under normal temperature and normal pressure conditions. The ice removal system according to any one of [10] to [12] above.
[14] A degassing tower is connected to the separator for degassing and recovering a gaseous substance separated under the normal temperature and pressure conditions separated by the separator, and the degassed gas is recovered. The ice removing system according to any one of [10] to [13], wherein the ice removing system is configured to be returned to the circuit.
[15] The ice removal system according to any one of [10] to [14], wherein the dehydrator causes the liquefied product and the ice-containing material to contact in countercurrent.

According to the present invention, it can be applied to various ice-containing materials regardless of the form and content of ice contained, and can be removed efficiently, and reuse and disposal of ice-containing materials can be achieved. An ice removal method useful for promoting and conserving resources is provided, as well as an ice removal system for efficiently performing the method.
In the ice removal method of the present invention, as a medium for removing ice, a substance that is a gas at normal temperature and normal pressure, that is, a gas that has high mutual solubility with ice and is close to the outside air temperature under atmospheric pressure. Since a liquefied substance is used, it is possible to remove ice at an operating temperature close to the outside air temperature without requiring severe conditions for contact with ice and separation from ice. Further, it is not necessary to evaporate the ice side at the time of separating the ice and the liquefied material, and there is no need to collect the latent heat of vaporization of the ice, and the ice can be removed with energy saving.

  Furthermore, the gas of the substance which is a gas at normal temperature and pressure separated from the water derived from ice can be easily recovered. Since the recovered gas can be circulated and used by liquefying again, it is also excellent in terms of energy efficiency. Then, by degassing the separated waste water, the liquefied material can be easily removed and the burden on the environment can be reduced.

Furthermore, according to the ice removal system of the present invention, it is possible to more efficiently proceed with ice removal using a substance that is gaseous at normal temperature and pressure.
Further, by connecting a heat exchanger, latent heat of vaporization can be recovered and used effectively. Furthermore, in the expander, further energy saving can be achieved by collecting work due to expansion.

  Therefore, the present invention can be widely applied to a process for removing ice from a substance. For example, means for drying a substance such as food that may be damaged by heat drying while keeping it at 0 ° C. or lower, means for removing a substance trapped in an ice block without heating, etc., on permafrost A method of removing buried substances while keeping them below 0 ° C, and removing moisture while keeping them below 0 ° C by freezing pharmaceutical compounds, compositions, proteins, etc. that are weak to heat and cannot be dried by heating It can be applied to the means for doing. In particular, it is expected to be used as an alternative technique for lyophilization. In addition, it can be reused easily by applying it to biomass resources. On the other hand, it is expected to be preferable in terms of resource protection because it is reduced by removing the ice to facilitate disposal. Further, it is expected as a means for removing moisture in place of freeze-drying in the production process of a porous material such as silica gel as disclosed in JP 2000-307294A.

It is the schematic which shows an example of a structure of the ice removal system of this invention. It is the schematic which shows the temperature pressure conditions of an example of the ice removal system of this invention. It is the schematic which shows an example of a structure of the ice removal system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'Compressor 2 Condenser 3 Dehydrator 4 Evaporator 4' Cooler 4 "Pressure reducing valve 5 Heat exchanger 6 Separator 7 Expander 8 Deaeration tower 8 'Holding valve 8a Heating can 9 Electric motor 10 Heater 21 Stainless steel container 22 Sealed container 23 Dehydrator 24 Ethanol tank

  The present invention relates to ice removal of ice-containing substances, and the greatest feature is that the solubility of ice is remarkably changed by utilizing a gas-liquid phase transition phenomenon of a substance that is a gas at normal temperature and pressure. is there. That is, a substance that is gaseous at normal temperature and normal pressure is subjected to treatment such as pressurization and cooling to form a liquid state. After the ice in the ice-containing substance is dissolved in the resulting liquefied product, the temperature and pressure are slightly changed. When changed, only the solvent selectively evaporates and the water and solvent gases are easily separated.

The ice-containing substance that is the subject of the present invention is not particularly limited as long as it is a substance containing ice.
“Ice” means frozen water or aqueous solution, and its composition, origin, etc. are not particularly limited. It also includes ice crystals such as snow.
“Contains” means that the above-mentioned ice is contained in the surface of any substance, inside, or both. There are no particular limitations on the size and components of any substance, but the ice-containing substance is preferably in the form of a solid or slurry.

There is no particular limitation on the form of ice in the ice-containing substance, and it is present on the ice or outer surface enclosed inside, between the solid particles, and in some cases, in the pores inside the solid particles. May be. Further, the content ratio of ice in the ice-containing material is not limited.
Specific examples of such ice-containing substances include coal, food, porous bodies, organisms, biomass raw materials (such as wood chips), pharmaceutical compounds, compositions, and proteins. The present invention can also be applied to a material that is difficult to dry by heating because it becomes brittle at high temperatures. Coal can be used as it is after mining, or after that some dehydration treatment (for example, reforming in oil (see JP 2000-290673 A), dehydration method using dry inert gas (special Even if it is made by Kaihei 10-338653)), it can be the subject of the present invention. Examples of types of coal include subbituminous coal, lignite, lignite, and peat.

The ice removing method and ice removing system of the present invention will be described below.
A. Ice removal method of the present invention An ice removal method of an ice-containing material using the liquefied material of the present invention is a method in which a liquefied material of a gas is brought into contact with an ice-containing material under normal temperature and normal pressure conditions, A step (1) of obtaining a liquefied product containing a high amount of water by dissolving ice in the ice-containing material, and evaporating a substance which is a gas under normal temperature and pressure conditions in the liquefied product containing a high amount of water It includes a step (2) of separating from moisture as a gas. Hereinafter, steps (1) and (2) will be described.

  First, in the step (1), a liquefied substance of a substance that is a gas under normal temperature and pressure conditions is brought into contact with an ice-containing substance, and the ice in the ice-containing substance is dissolved in the liquefied substance to contain a high moisture content A liquefied product is obtained.

  A substance that is a gas under normal temperature and normal pressure conditions means a substance that exists in a gaseous state at least under any temperature and pressure conditions within the range of normal temperature and normal pressure. That is, if it is a substance that shows a gaseous state under conditions of temperature A and pressure B included in the range of normal temperature and normal pressure, a temperature other than temperature A and a pressure other than pressure B included under the condition of normal temperature and normal pressure May not show a gas state.

Here, normal temperature means a temperature close to the outside air temperature in a cold region, and generally means a range of -50 ° C to 25 ° C, particularly -25 ° C to 10 ° C. The normal pressure means a pressure close to the external atmospheric pressure, and generally means a range around 1 atm.
As the substance that is gaseous under normal temperature and normal pressure conditions, specifically, a substance that is gaseous under the conditions of 25 ° C. and 1 atm, and a substance that is gaseous under the conditions of 0 ° C. and 1 atm are particularly preferable. Most preferred are substances that are in a gaseous state at 25 ° C. and 1 atm and in a gas state at 0 ° C. and 1 atm.

  The substance that is a gas under normal temperature and normal pressure conditions is preferably a substance having a boiling point near or below normal temperature from the viewpoint of enabling ice removal with a small required energy. In particular, the boiling point is 25 ° C. or less, preferably 10 ° C. or less, and more preferably −5 ° C. or less. A substance having a boiling point exceeding room temperature is not preferable because a high-temperature energy source is required to vaporize the substance in the step (2) described later, and the energy required for removing ice is expected to increase. Moreover, it is preferable that the substance that is a gas under normal temperature and pressure conditions does not contain sulfur, which is an environmentally hazardous substance that causes acid rain, in its molecular structure.

Specific examples of substances that are gaseous under normal temperature and normal pressure include dimethyl ether, ethyl methyl ether, formaldehyde, ketene, acetaldehyde, butane, propane, and the like. These may be used alone or in combination of two or more. Among these, dimethyl ether alone or a mixture of dimethyl ether and other substances described above as specific examples is preferable.
Dimethyl ether has a boiling point of −24.8 ° C. at 1 atmosphere and is a gas at atmospheric pressure of −10 ° C. to 50 ° C. For example, JP-A-11-130714, JP-A-10-195090, JP-A-10-195008, JP-A-10-182527 to JP-A-10-182535 are examples of high-efficiency dimethyl ether manufacturing methods and apparatuses. JP-A 09-309850 to JP-A 09-309852, JP-A 09-286754, JP-A 09-173863, JP-A 09-173848, JP-A 09-173845. And can be easily obtained according to the techniques disclosed therein.
On the other hand, in this invention, a liquefied material means the liquid obtained from gas by the liquefaction mentioned later. That is, in the present invention, a substance that is a gas under the above-described conditions of normal temperature and pressure is used in a liquid state.

In this step (1), a liquefied product of a substance that is a gas under normal temperature and normal pressure conditions is brought into contact with an ice-containing material, and the ice contained in the ice-containing material is dissolved in the liquefied product, whereby a liquefied product containing a high amount of water. Get.
That is, by bringing a liquefied substance of a substance that is a gas under normal temperature and normal pressure conditions into contact with ice contained in the ice-containing substance, that is, ice existing on the outer surface or inside of the ice-containing substance, Ice is dissolved as a liquid in the liquefied product to form a liquefied product containing ice at a high concentration.
Here, in order to bring a liquefied substance of a substance that is a gas under normal temperature and pressure conditions into contact with an ice-containing substance, it is necessary to maintain the substance in a liquid state. The method for maintaining the liquefied state is not particularly limited, but it is desirable to maintain the liquefied product at a saturated vapor pressure. In particular, the temperature condition in the step (1) is desirably set as appropriate in the range of −50 ° C. to 25 ° C., particularly in the range of −25 ° C. to 10 ° C.

Conditions other than temperature and pressure such as contact method, contact amount of liquefied material, contact time, etc. of the liquefied substance that is a gas under normal temperature and normal pressure conditions with respect to the ice-containing substance, the ice in the ice-containing substance is liquefied It is possible to appropriately set conditions that dissolve in the solution.
The contact method may be any method employed in a normal ice removal method, such as immersing an ice-containing material in a liquefied material, or circulating the liquefied material in an ice-containing material, but is preferably countercurrent contact. That is, it is preferable that the liquefied substance of the substance that is a gas is brought into contact with the ice-containing substance countercurrently under normal temperature and pressure conditions. Further, after the countercurrent contact, the countercurrent contact may be appropriately combined with other contact methods, for example, by immersing the ice-containing substance in the liquefied material and then performing the countercurrent contact again.

Moreover, the quantity of the liquefied material made to contact with an ice-containing substance can be determined suitably. In the present invention, the contact amount of the liquefied product with respect to the amount of water converted to ice contained in the ice-containing material is an amount that is greater than or equal to the theoretical amount of the following liquefied product, particularly an amount that is greater than or equal to the theoretical amount and less than or equal to twice the theoretical amount In particular, the object can be achieved even with a small amount that is not less than the theoretical amount and not more than 1.5 times the theoretical amount. However, in actual processing, it is desirable to set the amount of sufficient contact between the liquefied product and the ice contained in the ice-containing material. 0.1L / kg to 1000L / kg, preferably 0.5L / g to 900L / kg, more preferably 1.0L / g to 800L / kg. Can do.
Here, the theoretical amount of the liquefied product means a theoretical amount at least required for dissolving the ice in the ice-containing material to obtain a liquefied product having a high water content. That is, it means the minimum amount of liquefied material necessary for melting 1 g of water at a temperature at which the ice-containing substance and the liquefied material are brought into contact with each other. It can also be expressed as the reciprocal of pressure. For example, when dimethyl ether is used as a substance that is a gas under normal temperature and normal pressure conditions, and ice is one obtained by freezing 1 g of water, the theoretical amount of liquefied dimethyl ether necessary for dissolving ice for 1 g of frozen water is The saturated vapor pressure of dimethyl ether at −10 ° C. is 0.18 Mpa, and the saturated solubility of water in liquefied DME at −10 ° C. is 5.1 wt%, so 19.6 g.
The contact time (ice removal time) depends on conditions such as the type and amount of ice-containing substances and liquefied substances, the contact method, etc., and it is difficult to define uniquely, but the ice in the ice-containing substances is liquefied. The time for sufficient dissolution can be set as appropriate.

The general conditions in the case of countercurrent contact are as follows: the flow rate of the liquefied product can be 10 L / hour or more, preferably 30 L / hour or more, more preferably 50 L / hour or more, and the upper limit is generally 400 L / hour. It can be set to not more than time, preferably not more than 100 L / hour. The contact time can be 5 minutes or longer, preferably 8 minutes or longer, more preferably 10 minutes to 5 hours.
Moreover, when the general conditions in the case of immersion contact are shown, the liquefied product 10L can be brought into contact with the ice-containing material 85 g for 1 to 3 hours.

  In this way, in the step (1), a liquefied substance of a substance that is a gas under normal temperature and pressure conditions is brought into contact with the ice-containing substance, and the ice in the ice-containing substance is dissolved in the liquefied substance so that moisture is contained. A highly liquefied product can be obtained and at the same time the ice contained in the ice-containing material is removed.

  Next, in the step (2), a gas substance is vaporized under normal temperature and normal pressure conditions in the high-moisture content liquefied product obtained in the above (1) to separate it from water derived from ice as a gas. . That is, the high moisture content liquefied product obtained in the step (1) is in a state where a liquefied product of a substance which is a gas under normal temperature and normal pressure conditions and moisture derived from an ice containing material are mixed. By selectively vaporizing only a liquefied substance of a substance that is a gas under normal temperature and normal pressure conditions, it can be separated from water derived from the ice-containing substance.

Vaporization means changing a liquid (liquefied material) into a gas. Vaporization of a substance that is a gas under normal temperature and normal pressure conditions in a liquefied product containing a high amount of water can be performed by raising the temperature condition and / or pressure condition above each condition in step (1).
When raising the temperature conditions, it is preferable to raise the temperature to a temperature exceeding the boiling point of the substance that is gaseous under normal temperature and normal pressure conditions.However, in the present invention, a substance that is gaseous under normal temperature and normal pressure conditions is used. Usually, it can be vaporized under normal temperature, that is, near the outside temperature. That is, it is possible to vaporize only by returning from the cooling state of step (1) to the room temperature state rather than heating. The temperature condition for vaporization depends on the liquefied material to be used and the pressure condition, but it is preferably at room temperature, −50 ° C. to 25 ° C., particularly −25 ° C. to 10 ° C. When the pressure condition is lowered in the step (2), the condition is less than the saturated vapor pressure, and can be appropriately determined according to the temperature condition.

  In this way, in the step (2), a substance that is a gas under normal temperature and normal pressure conditions can be easily vaporized and converted from a liquid (liquefied product) to a gas without making it a severe condition. At the same time, this gas can be easily separated from ice or water derived from ice-containing materials.

  As described above, in the ice removal method of the present invention, ice can be removed from the ice-containing material by the above steps (1) and (2), but further, the ice is vaporized and separated in step (2). A step (3) of collecting a gas, which is a gas under normal temperature and pressure conditions, and liquefying the gas to obtain a liquefied product may be included.

Liquefaction means converting the gas of a substance, which is a gas, under a normal temperature and normal pressure condition into a liquid. Liquefaction of a substance that is a gas under normal temperature and normal pressure conditions can be performed by pressurization and / or cooling, that is, pressurization, or cooling, or a combination of pressurization and cooling. Considering the standard boiling point of the substance used, advantageous conditions can be selected as appropriate. In particular, when cooling is employed, the cooling temperature is preferably kept at the normal boiling point, and from the viewpoint of easily removing ice, it is within a range of room temperature, that is, outside air temperature, for example, −50 ° C. to 25 ° C., particularly −25. It is preferable to set in the range of 10 ° C to 10 ° C.
Moreover, when using the substance whose boiling point in 1 atmosphere exceeds 0 degreeC, it is preferable to liquefy by cooling above a boiling point. This is because the saturated vapor pressure of the material is less than 1 atm below the normal boiling point, and this causes the internal pressure of the device to be less than 1 atm, which increases the manufacturing cost of the device and makes handling difficult. .
Although it is difficult to generalize the conditions for pressurization, the boiling point under pressurization is set at room temperature, that is, in the range of outside air temperature, for example, in the range of −50 ° C. to 25 ° C., particularly in the range of −25 ° C. to 10 ° C. It is preferable. When used together with cooling, it can be determined according to the cooling temperature.

  By reusing the liquefied product obtained in the step (3) in the step (1), the amount of DME to be added in the ice removing method of the present invention can be reduced and the amount of waste can be reduced at the same time. From the viewpoint of resource protection.

  In addition, when it is necessary to proceed with ice removal in a frozen state, such as foods, compounds, etc. that may be damaged by heat drying, include the above steps (1) and (2), or as necessary It is preferable that the temperature condition in the step (3) is 0 ° C. or less, particularly −25 to 0 ° C. By performing the treatment in such a temperature range, the obtained ice-derived waste water can be deposited as ice.

  In the ice removal method of the present invention, since a liquid is used as an ice removal medium, the difference between the saturated solubility of ice in the liquefied product and the ice concentration in the liquefied product becomes the driving force for removing ice. The theoretical maximum amount of ice that can be dissolved in the liquefied product is proportional to the saturation solubility of ice and the weight of the liquefied product. When this is compared with the theoretical maximum value of the amount of ice that can evaporate in the dry inert gas conventionally used for removing ice from coal, the saturation solubility of ice is about 5.1% around -10 ° C. Very high with respect to the saturated vapor pressure partial pressure (approximately 0.26%) of water vapor in air at the same temperature. Such extremely high mixing ratios are not possible with gases, and here are the features that use liquids as the media for ice removal. Moreover, since the density of water is very large with respect to the density of water vapor, it is possible to remove ice with a small amount of liquefied material.

On the other hand, when removing ice by lyophilization, the pressure is reduced below the saturated vapor pressure of ice and the ice is sublimated. Since the saturated vapor pressure of ice is extremely low, the density of the latent heat of vaporization of water vapor is reduced, making it difficult to recover the latent heat of vaporization.
On the other hand, when a liquid is used as an ice removing medium as in the ice removing method of the present invention, the ice can be removed without evaporating, and the recovery of latent heat of vaporization is completely unnecessary. Moreover, since a liquefied substance of a gaseous substance is used as a liquid at normal temperature and normal pressure, that is, outside air conditions, it is adjusted to around 1 atm as necessary under the outside air conditions, that is, a temperature range of about −50 ° C. to 25 ° C. By doing so, a series of ice removal operations can be performed, and ice removal with energy saving is possible.

A substance from which ice has been removed by the ice removal method of the present invention can be reused as a raw material, and is expected to be used as an alternative technique for freeze-drying. For example, means for drying a substance such as food that may be damaged by heat drying while keeping it at 0 ° C. or lower, means for removing a substance trapped in an ice block without heating, etc., on permafrost A method of removing buried substances while keeping them below 0 ° C, and removing moisture while keeping them below 0 ° C by freezing pharmaceutical compounds, compositions, proteins, etc. that are weak to heat and cannot be dried by heating It can be applied to the means for doing.
In addition, it can be reused easily by applying it to biomass resources. On the other hand, it is expected to be preferable in terms of resource protection because it is reduced by removing the ice to facilitate disposal. In particular, it is expected to be used as an alternative technique for lyophilization.

B. Ice removal system of the present invention The present invention also provides an ice removal system using a liquefied product.
The ice removal system of the present invention includes a compressor that pressurizes a gas that is a gas under normal temperature and normal pressure conditions, a condenser that condenses the pressurized gas into a liquefied product, and the liquefied product. A dehydrator that is brought into contact with an ice-containing material to dissolve the ice in the ice-containing material to form a liquefied product with a high moisture content, and vaporizes a gas substance under conditions of normal temperature and normal pressure in the liquefied product with a high moisture content The evaporator is configured to be connected in series with a separator that separates the vaporized gas and moisture of the substance.
Such an ice removal system of the present invention is suitable for practicing the ice removal method of the present invention described in (A) above, and by using this system, the ice removal method of the present invention described above is used. It can proceed efficiently.

An example of the configuration of the ice removal system of the present invention is schematically shown in FIG.
In this example, it is assumed that dimethyl ether is used as a substance that is a gas under normal temperature and pressure conditions, but the system of the present invention is not limited to this. As described in (A) above, dimethyl ether has a boiling point of approximately −25 ° C. at 1 atmosphere and is a gas at atmospheric pressure of −25 ° C. to 10 ° C. Therefore, dimethyl ether in a liquid state (liquefaction of dimethyl ether) In order to obtain a product at room temperature, an operation under pressure is required.

  The ice removal system shown in FIG. 1 includes compressors 1 and 1 ′ for pressurizing dimethyl ether vapor, a condenser 2 for liquefying the pressurized vapor, and liquefied dimethyl ether (liquefied dimethyl ether) as an ice-containing substance. The dehydrator 3 that removes ice by bringing it into contact and dissolving ice to obtain a liquefied product containing a high amount of water (liquefied dimethyl ether containing water derived from ice), and the water derived from ice obtained as a result of ice removal The evaporator 4 that selectively vaporizes dimethyl ether from the contained liquefied dimethyl ether is connected in series by piping in this order. Among these, the condenser 2 and the evaporator 4 are connected by a heat exchanger 5.

In the system shown in FIG. 1, a separator (gas-liquid separator or gas-solid separator) 6 that separates dimethyl ether vapor obtained by vaporization in the evaporator 4 from water or ice, and a separator 6. An expander 7 that adiabatically expands the separated dimethyl ether vapor is connected in series by piping adjacent to the evaporator 4 in this order. The expander 7 is further connected to the compressor 1 to form a closed circuit (circulation path) as a whole system. Through this circuit, dimethyl ether circulates while changing the gas-liquid state, and the separation and contact with ice are repeated.
Further, a cooler 4 ′ and a pressure reducing valve 4 ″ are connected in series adjacent to the dehydrator 3. These are for adjusting the temperature and pressure when vaporizing the liquefied dimethyl ether. 4 may be positioned as a part of 4.

Further, in the system shown in FIG. 1, a deaeration tower 8 is connected to a separator 6. The deaeration tower 8 is for degassing the dimethyl ether dissolved in ice or water separated from the dimethyl ether by the separator 6. The dimethyl ether is vaporized and recovered. When the pressure inside the separator 6 is higher than the atmospheric pressure, dimethyl ether gas is dissolved in water (ice) separated by the separator 6. Therefore, if this water (ice) is discharged as it is, the load on the environment is large and the loss of dimethyl ether is further increased. Therefore, the deaeration tower 8 collects dimethyl ether dissolved in water (ice) to minimize the load on the environment and the loss of dimethyl ether.
The deaeration tower 8 is connected to the above circuit, and the dimethyl ether deaerated and recovered in the tower is returned to the circuit again by a pipe not shown.
In addition, by providing the heating can 8a for heating ice at the lower part of the deaeration tower 8, the separation of dimethyl ether from ice can be promoted, and the recovery rate of dimethyl ether can be improved.

In the expander 7, work to be performed outside is collected here, and this work is input and used as part of the power of the compressor 1 for pressurizing dimethyl ether. In addition, the compressor 1 has two stages of a first compressor 1 and a second compressor 1 ′, and the first compressor 1 is connected to the expander 7, and the work performed in the expander 7 is recovered, It is used as power for the first compressor 1. The work performed to the outside in the expander 7 mainly refers to what dimethyl ether gas performs with volume expansion. Moreover, since the superheated gas of dimethyl ether exiting the evaporator 4 may contain splashes entrained in the flow of superheated gas, the expander 7 may obtain work due to vaporization of the mixed splashes. , This is also included as work done to the outside world.
Further, since the condenser 2 and the evaporator 4 are connected by the heat exchanger 5, the latent heat of evaporation of the liquefied dimethyl ether is recovered and used effectively.
On the other hand, the second compressor 1 ′ is supplied with power by the electric motor 9, and work input from the outside is performed only to the second compressor 1 ′.

  Moreover, the heater 10 is installed in the system of FIG. The warmer 10 adjusts the temperature of the gas emitted from the expander 7 to the optimum temperature at the inlet of the compressor 1 and is installed as necessary depending on the use conditions of liquefied dimethyl ether.

The system of FIG. 1 involves three things: an ice-containing material, the ice contained in the material, and liquefied dimethyl ether. The flow of this system will be explained focusing on each substance.
First, as shown by the dotted line in FIG. 1, the ice-containing material is filled in the dehydrator 3, removed from the ice by contacting with liquefied dimethyl ether, and then removed from the container to finish the process.

Next, the flow of ice contained in the ice-containing material in the system of FIG. 1 will be described below. In FIG. 1, the flow of ice contained in the ice-containing material is indicated by a double line.
Ice is supplied to the system from the dehydrator 3 as ice contained in the ice-containing material. First, after elution from the ice-containing material into liquefied dimethyl ether by the dehydrator 3, the water reaches the evaporator 4 in the form of being dissolved as water in the liquefied dimethyl ether. Most of the liquefied dimethyl ether is vaporized in the evaporator 4 and water dissolved in the liquefied dimethyl ether is separated and reaches the separator 6. Further, the separator 6 is divided into dimethyl ether vapor and water.
Subsequently, the ice is introduced into the deaeration tower 8. When ice is introduced into the deaeration tower 8, the pressure inside the deaeration tower 8 is reduced by the pressure holding valve 8 ′ at the inlet, dimethyl ether is recovered, and the ice separated by the separator 6 is discharged as it is. The environmental burden as well as the loss of dimethyl ether can be minimized. In addition, the recovery rate of dimethyl ether can also be improved by heating water with the heating can 8a provided in the lower part of the deaeration tower 8. FIG.
The deaerated ice is discharged as a bottoms, and the dimethyl ether vapor separated from the waste water in the separator 6 can be returned to the circuit of the ice removing system and used again.

Next, the flow of dimethyl ether in the system of FIG. 1 will be described. In FIG. 1, the flow of dimethyl ether is indicated by a solid line.
Dimethyl ether gas is pressurized by the compressors 1, 1 ′ to become superheated gas, and then becomes supercooled liquid by the condenser 2. The supercooled liquid of liquefied dimethyl ether is supplied to the dehydrator 3 to come into contact with the ice-containing substance, dissolves the ice as water, and goes to the evaporator 4. The liquefied dimethyl ether is separated from water by the evaporator 4 and becomes superheated gas again. At this time, since the condenser 2 and the evaporator 4 are connected by the heat exchanger 5, the latent heat of evaporation of the liquefied dimethyl ether is recovered and used effectively. The dimethyl ether superheated gas exiting the evaporator 4 works in the expander 7 and is recovered as part of the compressor power. The dimethyl ether gas exiting the expander 7 is sent again to the compressor 1 and circulates in the system.

  In addition, when it is necessary to proceed with ice removal in a frozen state, such as a food or a compound that may be damaged by heat drying, the temperature condition of the system of the present invention is 0 ° C. or less, preferably − It is preferable to implement in the range of 25-0 degreeC. By performing the treatment in such a temperature range, the obtained ice-derived waste water can be deposited as ice.

  FIG. 2 shows a setting example of the phase state, pressure, temperature, and saturation temperature when dimethyl ether is used in one example of the system of the present invention. In order to simplify the design of pressure and temperature, it was assumed that the deaeration tower 8 for dimethyl ether gas from water was omitted, and that the separator 6 could completely separate water and dimethyl ether. Further, it was assumed that the ice-containing material treated in the dehydrator 3 does not contain dimethyl ether. Furthermore, it was assumed that the ice-containing material does not contain impurities as ice.

  First, temperature and pressure conditions were set starting from the temperature at the inlet of the first compressor 1. When the temperature at the inlet (1) of the first compressor 1 is −15 ° C. and is heated by 10 ° C. from the saturation temperature, the pressure becomes 0.10 MPa. Since the pressure in the first compressor 1 increases as the degree of superheat decreases, the power of the compressor 1 decreases. On the other hand, the danger that dimethyl ether gas is cooled and condensed by outside air at a stage before the compressor inlet. Increases nature. Moreover, since the heat capacity ratio of dimethyl ether is as small as 1.11, the temperature hardly rises during adiabatic compression. For this reason, the degree of superheat at the compressor outlets (2) and (3) in the first compressor 1 and the second compressor 1 'is smaller than the degree of superheat at the compressor inlet. In this system, it is necessary to pay attention to the degree of superheat at the compressor outlet when determining the degree of superheat at the compressor inlet.

  The pressure at the outlet (3) of the second compressor 1 ′ is determined from the temperature of the cooling water used in the cooler 4 ′ before the evaporator 4. Here, it is assumed that the outside air temperature is −15 ° C. and the temperature of the cooling water is equal to the outside air temperature. If the approach temperature in the cooler 4 'is 5 ° C, the temperature of the liquefied dimethyl ether at the outlet (evaporator inlet) (6) of the cooler 4' becomes -10 ° C. If the approach temperature between the condenser 2 and the evaporator 4 is 5 ° C., the temperature at the outlet (4) of the condenser 2 is −5 ° C. Assuming that dimethyl ether exists as a liquid having a saturation temperature in the dehydrator 3, the operating pressure of the condenser 2 (pressure at the compressor outlet) is determined. In this case, since the saturation temperature is −5 ° C., the outlet (4) of the condenser 2 and the outlet (condenser inlet) (3) of the compressor 1 ′ are 0.22 MPa. Assuming adiabatic compression, the temperature of the outlet (3) of the second compressor 1 'is 6 ° C, and the superheated gas exceeds the saturation temperature of dimethyl ether at the compressor outlet.

  Since the saturation temperature of the evaporator 4 is −10 ° C., it is necessary to reduce the pressure to the saturation pressure at −10 ° C. at the inlet (6) of the evaporator 4. The saturation pressure here is the saturation pressure of a mixed liquid of water in which ice is dissolved and liquefied dimethyl ether, and here it is approximately 0.18 MPa as the saturation pressure of dimethyl ether having a high vapor pressure. Further, since the temperature difference between the condenser 2 and the evaporator 4 is 5 ° C., the temperature at the outlet (expander inlet) (7) of the evaporator 4 is 1 ° C. Since the superheat degree here is 11 ° C., the heat loss within the energy range required for heating the dimethyl ether gas at 11 ° C. is within the range from the outlet of the second compressor 1 ′ to the inlet of the expander 7. acceptable.

  After separating the dimethyl ether gas from the water by the separator 6, it is adiabatically expanded by the expander 7. The pressure at the outlet (8) of the expander 7 is equal to the pressure at the first compressor 1 inlet. Dimethyl ether gas is cooled to -16 ° C by adiabatic expansion. Since the temperature of 1 ° C. is lower than that of the inlet of the first compressor 1, heating is necessary. In the expander 7, energy is recovered and used as power for the first compressor 1. Assuming that the heat insulation efficiency in the expander 7 and the first compressor 1 is 80%, the temperature at the outlet of the first compressor is determined to be −5 ° C. and the pressure is set to 0.15 MPa.

Further, the required power in the second compressor 1 ′ is calculated assuming that the mechanical efficiency in the expander 7 and the two compressors 1 and 1 ′ is 0.8 in accordance with the temperature and pressure setting already determined.
First, the total work required by the two compressors 1 and 1 ′ is (theoretical work required by the two compressors 1 and 1 ′) ÷ 0.8. On the other hand, the work recovered by the expander 7 and input as the power of the first compressor 1 is (theoretical work to be expanded) × 0.8. Therefore, the work required for the second compressor 1 ′ is (theoretical work required for the two compressors 1, 1 ′) ÷ 0.8−theoretical work for the expansion) × 0.8. Furthermore, since this work needs to be introduced in the form of power, if the conversion efficiency is 0.35, the work required by the second compressor 1 ′) ÷ 0.35 is the second compressor 1 ′. The total energy required. This conversion rate is the same value as the conversion efficiency of the compression power for recovering the latent heat of steam used in the power estimation of the reforming method in oil.

Here, dimethyl ether is approximated to an ideal gas, adiabatic compression is assumed, and the saturation power of ice at -5 ° C. in liquefied dimethyl ether is assumed to be 5.4 wt%. Is 1383 kJ / kg-water.
From this estimation result, it was theoretically confirmed that the ice removal system of the present invention can achieve ice removal with a small amount of required energy.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

Example 1 (Dehydration test of frozen wood pieces)
A dry wood piece coarsely crushed to a thickness of 1 to 3 mm and a length of about 1 cm is immersed in water (dry weight 0.9345 g, wet weight 3.0006 g) and placed in a glass column having an internal volume of about 14 cc. It was cooled by freezing for one day and night, and this was used as a batch for the test.

The frozen piece of wood prepared as described above was dehydrated using liquefied dimethyl ether (DME) having a purity of 99% or more with the apparatus shown in FIG.
That is, the frozen wood pieces packed in the glass column corresponding to the dehydrator 3 in FIG. 1 are filled with the liquefied DME with saturated vapor pressure in the stainless steel container 21 in FIG. I let you. And liquefied DME was collect | recovered with the empty airtight container 22 which stores liquefied DME. In addition, the whole apparatus was put into an ethanol tank 24 maintained at -23 ° C, and a dehydration test was performed while the piece of wood was frozen at a temperature of -23 ° C.
The flow rate of liquefied DME was 10 cc per minute, and was circulated for 10 minutes. In addition, the ratio of the flow rate of 0.01L of liquefied DME with respect to 0.0020661kg of moisture content of the object to be dehydrated is 4.84L / kg per minute. The saturated solubility of water in liquefied DME at −19.45 ° C. is 4.3 wt%, and the DME required to dissolve 1 g of water at a saturated concentration is 23.3 g.
After completion of the dehydration treatment, the sealed container 22 was removed from the apparatus, and the valve of the sealed container 22 was opened at room temperature to evaporate DME, thereby separating DME and water. After DME was evaporated, the water remaining at the bottom of the sealed container 22 was used as drainage.

  After completion of the dehydration treatment, the weight of the wood pieces before and after dehydration, the weight reduced before and after the dehydration treatment (weight reduction), and the weight of the waste water were measured. Table 1 shows the results.

As is apparent from Table 1, the weight of the wood pieces after the treatment was significantly reduced as compared with that before the treatment. Further, the treated wood pieces were dehydrated around the left side of the column, which is the inlet of the liquefied DME, while retaining moisture on the right side of the column, which is the outlet of the liquefied DME. This is because liquefied DME is a process in which liquefied DME flows through the wood pieces, and it takes time to dissolve the water of the frozen wood pieces. This is because dehydration on the right side of the column starts after dehydration on the right side of the column proceeds.
From this, according to the present invention, it was confirmed that a large amount of frozen water could be easily removed from a frozen (hydrated) wood piece in a frozen state at a temperature below freezing point in a short time.

Example 2 (Dehydration test of frozen coal)
After coarsely pulverizing, using a 4 mm sieve mesh and an 8 mm sieve sieve, the wallet charcoal (Indonesian subbituminous coal) with a particle size of 4-8 mm is collected, and fresh water is accumulated at the bottom to maintain humidity. The coal (wet weight 2.397 g) was obtained by allowing it to stand at 100% for 1 year. This coal was packed in a part of a glass column having an inner diameter of 11 mm and a length of 42 mm (volume: about 4 ml). The remaining void of the glass column was filled with inert quartz wool. The sample was cooled in a freezer for one day and frozen to be used as a batch.

The frozen piece of wood prepared as described above was dehydrated using liquefied dimethyl ether (DME) having a purity of 99% or more with the apparatus shown in FIG.
That is, frozen coal packed in a glass column corresponding to the dehydrator 23 in FIG. 3 is filled with liquefied DME having a saturated vapor pressure in a stainless steel container 21 corresponding to the compressor in FIG. The dehydrator 23 was circulated. And liquefied DME was collect | recovered with the empty airtight container 22 which stores liquefied DME. In addition, the whole apparatus was put into an ethanol tank 24 maintained at −10 ° C., and a dehydration test was performed while the coal was frozen at a temperature of −10 ° C.

  The flow rate of liquefied DME was 5 cc per minute and was circulated for 13 minutes. The saturated solubility of water in liquefied DME at −9.5 ° C. is 5.1% by weight, and 19.6 g of DME is required to dissolve 1 g of water at a saturated concentration.

  After completion of the dehydration treatment, the sealed container 22 was removed from the apparatus, and the valve of the sealed container 22 was opened at room temperature to evaporate DME, thereby separating DME and water. After DME was evaporated, the water remaining at the bottom of the sealed container 22 was used as drainage.

  After completion of the dehydration treatment, the weight of coal before and after dehydration, the weight reduced before and after the dehydration treatment (weight reduction), and the weight of waste water were measured. Table 2 shows the results.

  As is apparent from Table 2, the weight of coal after treatment was significantly reduced compared to that before treatment.

Example 3
In Example 2, the coal before and after the dehydration treatment was allowed to stand at 107 ° C. for 3 hours, and the same dehydration treatment was performed except that the moisture was evaporated. The moisture content of the coal before and after the dehydration test was measured. Table 3 shows the results.

  As is apparent from Table 3, the moisture of the coal before dehydration was (0.815 ÷ 1.921 =) 42.4% by weight, whereas the moisture of the coal after dehydration was (0.593 ÷ 1. 922 =) 30.9% by weight. In other words, the coal before dehydration contained 0.736 weight of water, whereas the weight of the combustible component of coal was 1 (that is, when the weight of coal after heating was 1), After dewatering, the coal only contains 0.447 weight of water. As described above, according to the present invention, it was confirmed that a large amount of frozen water can be easily removed from frozen hydrous coal in a short time at a temperature below freezing point.

As described above, the ice removing method according to the present invention can be applied to various ice-containing materials, and any ice-containing material can easily remove ice in a short time with low power.
Therefore, the present invention aims to reduce the weight by removing ice from various ice-containing materials, and facilitates processing as waste, reuse, use of resources as biomass, and the like.

Claims (15)

  A step (1) of bringing a liquefied product of a substance that is a gas under normal temperature and normal pressure conditions into contact with an ice-containing material, and dissolving the ice in the ice-containing material in the liquefied product to obtain a liquefied product having a high water content; And ice using a liquefied product, characterized in that it comprises a step (2) of separating the gas as a gas by evaporating a gaseous substance under normal temperature and normal pressure conditions in the liquefied product containing a high amount of water A method for removing ice from contained substances.   The step (3) further includes a step (3) of recovering a gas of a substance that is vaporized and separated in the step (2) under normal temperature and normal pressure conditions, and liquefying the gas to obtain a liquefied product. The method of removing ice according to claim 1, wherein the liquefied product obtained in step (1) is used again in the step (1).   The method for removing ice according to claim 1 or 2, wherein the substance that is a gas at normal temperature and pressure is a substance that is a gas at 25 ° C and 1 atm.   The substance which is a gas under normal temperature and normal pressure conditions is one or a mixture of two or more selected from dimethyl ether, ethyl methyl ether, formaldehyde, ketene, and acetaldehyde. The ice removal method as described in any one.   The ice removing method according to any one of claims 1 to 4, wherein the ice-containing substance is coal, food, a porous body, a living organism, a biomass raw material, or a pharmaceutical compound.   The ice removal method according to claim 1, wherein the contact in the step (1) is performed such that the liquefied product and the ice-containing substance are brought into countercurrent contact.   The amount of the liquefied product brought into contact with the ice-containing substance in the step (1) is 0.1 L / kg to 1000 L / kg per amount of water converted to ice contained in the ice-containing substance. 6. The ice removing method according to any one of 6 above.   The ice removal method according to any one of claims 1 to 7, wherein the series of ice removal operations is performed in a temperature range of -50 ° C to 25 ° C.   The substance from which the ice obtained by the ice removal method as described in any one of Claims 1-8 was removed.   A compressor that pressurizes a gas that is a gas under normal temperature and normal pressure conditions, a condenser that condenses the pressurized gas into a liquefied product, and the liquefied product is brought into contact with an ice-containing material so that the ice A dehydrator that dissolves ice in the contained material to form a liquefied product with a high moisture content, an evaporator that vaporizes the gaseous material under normal temperature and normal pressure conditions in the liquefied product with a high moisture content, and the vaporized product An ice removal system for an ice-containing material, wherein a separator for separating a gas and moisture of the material is connected in series.   The ice removing system according to claim 10, wherein the condenser and the evaporator are connected by a heat exchanger.   Further, an expander that expands the gas of the gas substance under the condition of the vaporized normal temperature and normal pressure is configured to be connected in series to the compressor, and the work to be performed to the outside of the expander is recovered, and the work The ice removal system according to claim 10 or 11, wherein the ice removal system is configured to be input as a part of power of the compressor.   The compressor, the condenser, the dehydrator, the evaporator, and the expander form a circuit, and the circuit is configured to circulate a gaseous substance under normal temperature and pressure conditions. Item 13. The ice removal system according to any one of Items 10 to 12.   A degassing tower is connected to the separator for degassing and recovering the gaseous substance separated under the normal temperature and normal pressure conditions separated by the separator, and the degassed gas is recovered and returned to the circuit. The ice removal system according to any one of claims 10 to 13, wherein the ice removal system is configured to be configured as described above.   The ice removal system according to any one of claims 10 to 14, wherein the dehydrator makes the liquefied product and the ice-containing substance come into countercurrent contact.

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