DE10015806C2 - Storage for liquid ice with high ice concentration - Google Patents

Description

The invention relates to a memory for liquid ice, in particular for pumpable liquid ice high ice concentration, with at least one inlet and at least one outlet and with an agitator arranged in the memory, which is driven by a drive motor becomes.

Various types of storage for liquid ice are known, which either serve to extract ice of high concentration by means of rotating scrapers (e.g. US 5,035,733 and US 4,912,935) or are used as buffer stores in a cooling circuit of low ice concentration (e.g. WO 96 / 27109 and TEXTBOOK OF REFRIGERATION TECHNOLOGY, 4th edition 1997 , CF Müller Verlag, Heidelberg, picture 5/28, page 305). The prior art is that the ice stores are designed as standing cylinders. Due to the different density of the liquid ice components, there is a gravitational separation of ice particles and water, which is stronger the higher the cylinder is built. In the case of the ice extraction system, this "favorable" effect is exploited: at the point of the highest ice concentration, scrapers rotate, which pick up and remove the ice. In the case of the buffer storage, this "unfavorable" effect means that the liquid ice clumps or glaciates on the surface and is then difficult or impossible to pump.

For this reason, an agitator with one or more horizontal or slightly inclined mixing arms integrated in the ice storage, which ensures a continuous Circulation and mixing of the liquid ice ensures and thus the tendency to clump counteracts.

In the agitator described in EP 0 923 969 A1, the agitator arms of the Agitator with rows of combs, which are arranged on the cylinder wall of the agitator.  

The stirrer arms are often used as propellers to achieve vertical movement of the liquid ice trained, so twisted along its axis, which is quite with low ice concentrations works (DE 36 24 352 A1). However, such agitators have disadvantages or Functional restrictions.

If such a stirrer is used to dispense liquid ice (a suspension of maximum equal proportions of ice crystals and water and a very small proportion of Mixing the freezing point) will be useful Peripheral speeds despite the known methods for vertical flow Training by means of suitably shaped stirring arms a serious separation of the adjust specifically light ice crystals and the specifically heavy water molecules. Only when the agitator speed increases significantly can the actually desired one vertical circulation of the liquid ice and thus complete homogenization become; but then the energy coupled in via the agitator arms is so great that the Ice crystals melt and therefore the agitator container does not act as a liquid ice storage can be used.

The object of the invention described below is therefore the construction of a Storage with integrated agitator, the pumpable, non-clumping liquid ice with provides high ice concentration, when using under normal atmospheric conditions evaporating freezing point depressors this evaporation should be prevented so that the freezing point of the liquid ice or brine as well do not change other physical properties.

This object is achieved by the features of claim 1, advantageous Refinements are the subject of the dependent claims.  

The basic ideas of the invention are through a horizontal arrangement of a cylindrical ice storage the effects of gravitational Reduce ice concentration change above the level of the store by a likewise horizontally arranged agitator for a vertical instead of a previously mainly horizontal circulation of the liquid ice and by rotating as well fixed agitator elements to achieve that the formation of clumps is prevented.

Evaporation of freezing point depressants is reduced by the fact that the liquid ice Circuit is closed to the outside and the volume expansion of the formed Ice in an expansion tank connected to the bottom of the reservoir is recorded, which is only partially insulated thermally or is not insulated at all.

An embodiment of the liquid ice storage device according to the invention is shown in FIG Drawing are explained. Show it:

Fig. 1: Storage for liquid ice with a longitudinal section of the agitator

Fig. 2: Storage for liquid ice with vertical section and agitator

Fig. 3: Storage for liquid ice with a surge tank

Fig. 1 shows a thermally insulated storage for liquid ice, which is designed as a horizontally or almost horizontally arranged cylinder 1 , in which the stirrer 5 also arranged horizontally causes a vertical circulation of the liquid ice. The central axis of the cylinder 1 can also have an inclination angle of up to 15 ° with respect to the horizontal.

The store is provided with at least one inlet 6 and at least one outlet 7 , arranged along the outer wall or on the end faces of the cylinder 1 . In the example, the inlet 6 is arranged at the top of the outer wall of the cylinder 1 on one side and the outlet 7 at the bottom of the outer wall of the cylinder 1 on the other side.

The agitator 5 is rotatably arranged on the central axis of the cylinder 1 and has stirring arms 2 directed inward into the cylinder space, preferably at right angles to the central axis. In the embodiment shown, the stirring arms 2 are comb-shaped, and at least one row of combs extends over the length of the cylinder 1 or parts thereof.

Furthermore, there are fixed, spaced, rod-shaped tines 3 pointing along or partially along the inner wall of the cylinder 1 to the central axis. The fixed tines 3 extend close to the axis of rotation of the agitator 5 and are also comb-shaped in the illustration.

When the agitator 5 rotates, the agitator arms 2 comb through the liquid ice located in the cylinder 1 and, due to the horizontal arrangement of the agitator 5, cause the liquid ice to be exchanged between the top and bottom. This prevents the formation of ice clumps up to a certain ice concentration. Due to the centrifugal effect of the rotating liquid ice, as with vertical storage, specifically heavy liquid ice components, i.e. those with the greater water content, are transported to the outside, while the specifically lighter components remain in the vicinity of the axis of rotation. In contrast to vertical storage, these effects are smaller due to the additional gravitational separation, but at high ice concentrations they can be noticed in such a way that an ice block forms around the axis of rotation, which increases with time. In order to counteract this on the one hand and on the other hand to further increase the possible ice concentration, the rod-shaped tines 3 fixed on the inside of the cylinder 1 , preferably at the bottom in the form of a comb, are present, on which ice clumps that form are immediately separated. If the rod-shaped tines 3 or some of them are hollow, they can be used to hold electrical heating elements, with which the liquid ice can also be melted off if necessary.

Fig. 2 shows the same memory in vertical section. To intensify the action of the agitator 5 , further rotating and other fixed combs made of agitator arms 2 and / or tines 3 can be added. The stirring arms 2 and tines 3 do not have to be arranged in alignment, but they can be offset from one another in order, for. B. to effect a defined transport of the liquid ice from the inlet 6 to the outlet 7 .

The viscosity of the liquid ice is a function of the ice concentration. As studies have shown, the viscosity of liquid ice changes significantly with the ice concentration, especially in the area of high ice concentrations. The power consumption of the agitator 5 is thus a function of the viscosity of the liquid ice. It is therefore possible to use the power consumption of the drive motor 4 of the agitator 5 or its change in speed as a signal for a changing ice concentration in a limited range of high ice concentration and, if necessary, to counteract it. It has proven to be a simple method to record a calibration curve for the ice concentration as a function of the speed of the driven motor 4 and thus of the agitator 5 and to regulate the ice concentration on the basis of the speed.

To prevent evaporation of freezing point depressants from the brine (water + Freezing point lowers) or out of the liquid ice with the invention proposed to complete the liquid ice cycle at least temporarily. It must be for the volume increase associated with ice formation created an expansion space become. If this space were above the surface of the liquid in the storage container, With changing ice concentrations in this area there can be clumping and Glaciations of ice are coming, and it can happen that air is in front of it Commissioning of the system in the store has been stirred with the liquid ice is, which makes it compressible, but the usable enthalpy of fusion is reduced.  

For these reasons, as shown in Fig. 3, an expansion volume is created in a separate expansion tank 8 , which is connected via a non-thermally insulated line 9 below to the cylinder 1 of the memory. The line 9 can be heated. With increasing ice concentration and thus increasing volume, liquid ice flows into the connecting line to the expansion tank 8 and compresses the air present there, as a result of which the total pressure in the system only increases slightly. The volume of the expansion tank 8 is to be dimensioned such that the total system pressure cannot rise above a tolerable value. If this should happen under unforeseen conditions, air or steam is blown off via a pressure relief valve 10 , so that the total system pressure is reduced. The lack of thermal insulation on the connecting line 9 and possibly on parts of the expansion tank 8 ensures that no solid ice can form in the connecting line, which could impair or prevent liquid ice from flowing back and forth.

LIST OF REFERENCE NUMBERS

1

cylinder

2

Agitator arms (movable)

3

Tines (fixed)

4

drive motor

5

agitator

6

Intake

7

procedure

8th

surge tank

9

management

10

Pressure relief valve

Claims (12)

1. Storage for liquid ice with at least one inlet ( 6 ) and at least one outlet ( 7 ) and with a stirrer ( 5 ) arranged in the store and driven by a drive motor ( 4 ), characterized in that the store is designed as a horizontal or almost horizontally arranged cylinder ( 1 ) is formed, in which the likewise horizontally arranged agitator ( 5 ) causes a vertical circulation of the liquid ice. 2. Memory according to claim 1, characterized in that the central axis of the cylinder ( 1 ) has an inclination angle of up to 15 ° with respect to the horizontal. 3. Storage according to claim 1, characterized in that along the outer wall or on the end faces of the cylinder ( 1 ) at least one inlet ( 6 ) and at least one outlet ( 7 ) are arranged. 4. Memory according to one of claims 1 to 3, characterized in that the agitator ( 5 ) is rotatably arranged on the central axis of the cylinder ( 1 ) and has inwardly pointing in the cylinder space stirring arms ( 2 ). 5. Storage according to claim 4, characterized in that the stirring arms ( 2 ) are comb-shaped and at least one row of combs extends over the length of the cylinder ( 1 ) or parts thereof. 6. Memory according to claim 4 or 5, characterized in that along or partially along the inner wall of the cylinder ( 1 ) to the central axis, fixed, spaced, rod-shaped tines ( 3 ) are arranged, which of the stirring arms ( 2 ) at the Rotation to be combed. 7. Storage according to claim 6, characterized in that the fixed spaced tines ( 3 ) of the inner wall of the cylinder ( 1 ) extend close to the axis of rotation of the agitator ( 5 ). 8. Storage according to one of claims 6 to 7, characterized in that the rod-shaped tines ( 3 ) or some of them are heatable. 9. The memory according to claim 1, characterized in that the cylinder ( 1 ) is connected at the bottom via a line ( 9 ) to an expansion tank ( 8 ). 10. The memory according to claim 9, characterized in that the line ( 9 ) is heatable. 11. The memory according to claim 9, characterized in that the expansion tank ( 8 ) has a pressure relief valve ( 10 ). 12. The memory according to claim 9, characterized in that the expansion tank ( 8 ) and / or the line ( 9 ) are partially thermally insulated.