DE102013010510B4 - Flooded evaporator with integrated liquid separation - Google Patents

Abstract

Device for the separation of refrigerant liquid and gas and for returning liquid refrigerant in the evaporation process of refrigeration or refrigeration systems, characterized in that an evaporator tube bundle or plate package 2 in the space to an upper container shell 1 with a round suction 7 a multi-part Prallabscheide-, drain - And distributing device is arranged in the length of the evaporator, consisting of: a 23 ° oblique perforated plate 4 with holes of 2 to 4 mm diameter, with a free hole area of 40% in the upper and middle region 4a, which is such that their gas flow at full load below the entrainment speed for liquid, and a free hole area ≥ 60% in the lower area 4b, through which liquid flows; a relative to the suction nozzle 7, the perforated plate 4 in the flow direction upstream baffle plate 4c, performed in two Saugstutzenbreite with lateral folds, so that at the same time forms a protected drainage channel towards evaporation jacket 1; and an over the oblique perforated plate 4 arranged U-shaped flow channel 5 of perforated plate with holes of 2 to 4 mm in diameter, which includes the suction nozzle 7 and runs with 1.4 times Saugstutzenbreite in the axial direction, with its legs to the evaporator shell 1 finishes and has a free hole area of 40%, which is such that its gas flow at full load remains below the entrainment speed for liquid.

Description

The invention relates to the arrangement and design of an integrated into the evaporation vessel means for separating liquid fractions of gaseous refrigerant after evaporation and before container exit and for returning the separated liquid refrigerant in the evaporation process.

In the case of flooded evaporation on tube bundles or plate packs without overheating, so-called thermosiphon or gravity systems, refrigerant is injected via control valves into a separate liquid separator which separates liquid and gas. The liquid then flows through a return line (gravity circulation) from below into the tube bundle or plate pack and evaporates there in part. Unevaporated liquid flows with the gaseous refrigerant back into the separator and is separated there, see textbook "Ammonia / R22 refrigeration systems, control and safety" CF Müller Verlag GmbH, Heidelberg 1995, Fig. 12 and 15. The liquid separation is to protect the Compressor required before liquid. The versions with separate liquid separator are bulky and hinder the compact design of refrigeration kits.

In books such as "ammonia compressor refrigeration systems Vol. 2 assembly and operation" Verlag CF Müller Karlsruhe 1993, Fig. 3-21 also collector of evaporator systems are described with pump circulation, in which liquid refrigerant is pumped from the lower part of the collector in separately arranged evaporator , There partially evaporated and flows with the remaining liquid back into the collector. After separation of the liquid, the gaseous refrigerant leaves the collector to the compressor. These designs are common for refrigeration systems and not compact.

Solutions with integrated liquid separator are known from the prior art. The FI 20080576 A ( FI 123371 B ), F25B 43/04, Vahterus Oy discloses a flooded evaporator with integrated liquid separation and internal refrigerant circulation. This refrigerant is released directly into the evaporator and evaporated. Before the gaseous refrigerant leaves the evaporator, liquid droplets torn out of the evaporation process are to be separated. Disadvantageously, it comes from poorly drained liquid already deposited and their displacement in the liquid separator in the direction of suction for supercritical fluid load of the suction gas. Due to high gas velocities close to the suction nozzle, inadmissibly much liquid is entrained.

The modified solution of Fa. Vahterus Oy, disclosed in WO 2012/107645 eliminates the problem of fluid displacement in the liquid separator by using permeable perforated sheet demister assemblies with low gas pressure drop and tendency to evaporator jacket. Thus, separated liquid will preferably drain from the gas stream towards the apparatus jacket and back into the evaporation process. In the area of the suction nozzle occurring gas velocity peaks, however, lead to the disadvantageous entrainment of liquid droplets from the nearby perforated plate demister areas in the suction. Effective solutions with wire knit demisters require larger flow-through thicknesses up to 150 mm, which are expensive and disadvantageous for the required flat design of the integrated liquid separator.

Furthermore, a solution with integrated liquid separator, as in the publication US 2008/030 21 30 A1 which combines impingement deposition with demister wire mesh and shows drainage of deposited liquid from the gas flow area. A measure against local aspiration of liquid droplets in position of the suction is not recognizable.

The publication DE 603 10 876 T2 shows a conventional T-shaped Sauggassammler in the field of liquid separation for the most uniform extraction over the entire outflow surface of an evaporator package without details for liquid separation and in another view a conventional obliquely arranged Demister for liquid separation from gas flows without further description. Solutions with wire knit demisters are expensive.

The publication JP 2008-138 891 A shows an integrated liquid separator, which consists of a one- to multi-stage obliquely arranged demister structure, with up to two horizontal perforated plates on the evaporator tube bundle and a directly demi right on the lowest demister obliquely arranged perforated plate to equalize the gas velocity.

The liquid separation take over here expensive demisters. Due to the oblique arrangement, separated liquid advantageously runs in the direction of the container jacket and not into the gas stream. However, liquid can already be deposited on the horizontal perforated plates to even out the gas velocity, and this liquid drips disadvantageously into the gas stream again without a predetermined flow direction. The in the publication JP 2011-021 856 A shown variants try with different arrangements of demister elements equalization of the speed of vaporized Refrigerant through the demister elements themselves. However, deposited liquid can partially run off and sucked off of closed sheet metal surface directly opposite the suction nozzle. Even a dished demister solution whose lowest point is directly above the container axis and under the suction, already deposited refrigerant liquid can be disadvantageously dripped back into the gas stream and at the same time an accumulation of liquid directly opposite the suction arise, which can lead to entrainment of liquid parts.

The object of the invention is to provide means for separating refrigerant liquid and gas and for returning liquid refrigerant in the evaporation process, with which refrigerant is sucked over the evaporator so that expelled liquid fractions from the evaporator bundle or plate pack do not accumulate in the deposition and accumulation be sucked out there in Saugstutzenbereich, but backed up in the evaporation process can run back.

According to the invention, this object is achieved in that a multi-part Prallabscheide-, drain and Sauggassammeleinrichtung is arranged above an evaporator tube bundle or plate package in the space to the upper container shell with the suction directly over the boiling refrigerant and the refrigerant injection with the main separation by a in the area 15 ° to 45 ° oblique, preferably 23 ° to the horizontal inclined perforated plate with holes ⌀ 2 to 4 mm begins, while the free hole area of preferably 40% in the upper and middle range is such that the gas flow rate remains below the entrainment speed for liquid and In the lower area leading to the tank wall, liquid can flow away through a free hole area ≥ 60%.

Underneath this perforated plate, a U-shaped baffle plate and drainage channel are preferably also twice as wide as the round suction nozzle transversely to the evaporator axis at its approximately 15 mm high lateral legs so that a channel opening points downwards.

Over the length of the evaporator and as a further separation device, a flow channel in the axial direction of perforated plate with holes ⌀ 2 to 4 mm and free hole area of preferably 40% is at least 1.3 times wider than the suction arranged under the suction nozzle, wherein the legs on the container wall sit up and the channel floor is parallel to the oblique Hauptabscheideeinrichtung. The channel serves as a suction collector and is intended to reduce axial gas velocity components below the channel and produce a uniform upward velocity distribution. At the same time, the perforated plate is a droplet separator and, thanks to its oblique arrangement, quickly directs liquid downwards.

The free hole surface of the arranged Abscheidevleche is generally dimensioned so that at full load refrigerant liquid is neither sprayed nor entrained, d. H. Gas velocities are smaller than the Entraiment- or entrainment, which may be, for example, for ammonia refrigerant in the air-conditioning at 1.4 m / s.

The invention will be explained in more detail with reference to an exemplary embodiment.

The accompanying drawing shows in

The cross-section of a flooded evaporator with integrated facilities for impact separation and discharge of liquid refrigerant and for Sauggasverteilung
and in

the cut AA

The flooded evaporator with integrated liquid separation consists of: evaporator jacket 1 , Tube bundle or plate package 2 , Injection distributor 3 , Main separation and drainage device 4 made of perforated plate for liquid separation in the upper and middle area 4a and perforated plate in the lower area 4b as liquid drain as well as the baffle plate and drainage channel 4c only in the area of the suction nozzle 7 , about 4 is a separation, drainage and suction collecting device 5 of perforated plate channel-shaped arranged in total axial length, in which the suction nozzle 7 empties. The tube bundle or plate pack has a refrigerant-liquid reservoir 6 , A spray 6a from refrigerant liquid and gas escapes 2 and 3 up.

The separation of liquid begins at the main separation and drainage device 4 , This is where most of the spray cracked and injected from the evaporation process becomes 6a by changing the flow direction and impact on the perforated plate 4a and 4c collected. The velocity of the gas flowing through the holes is so low that no liquid is sprayed. At the slope of the perforated plate, separated refrigerant flows quickly towards the evaporator jacket 1 and runs there undisturbed back into the refrigerant liquid reservoir 6 , wherein the free hole area of the perforated plate 4b of ≥ 60% causes the rapid outflow of liquid coming from above.

In the area of the suction nozzle 7 Spikes of fluid could pass through the two separator devices 4 and 5 Pull into the suction nozzle. That prevents one opposite 7 under the perforated plate 4a transverse to the evaporator axis arranged baffle channel 4c that is at least twice as wide as the suction nozzle 7 is. The baffle channel 4c at the same time ensures drainage on the perforated plate 4a In the range of 7 deposited liquid deposited and their undisturbed by rising gas drain down towards the evaporator jacket 1 ,

contraption 5 is Sauggassammler, separation and drainage device in one and is made of a U-shaped perforated plate channel as long as the evaporator jacket 1 in front of the suction nozzle 7 educated.

So that deposited liquid refrigerant does not collect and jam at the bottom of the perforated plate channel, this is oblique and parallel to the main separation and drainage device 4 executed, the liquid runs quickly to the lowest point and from there on the free hole area down from.

LIST OF REFERENCE NUMBERS

1

evaporator jacket

2

Tube bundle or plate pack

3

Injection manifold

4

Main separation and drainage device

4a

Perforated sheet in the upper and middle area

4b

Perforated sheet in the lower area

4c

baffle

5

Separating and drainage and suction collecting device

6

Refrigerant liquid reservoir

6a

Spray of refrigerant liquid and gas

7

suction

Claims (3)

Device for separating refrigerant liquid and gas and for returning liquid refrigerant in the evaporation process of refrigeration sets or refrigeration systems, characterized in that over an evaporator tube bundle or plate package 2 in the space to an upper container shell 1 with a round suction nozzle 7 a multipart Prallabscheide-, drain and distribution device is arranged in the length of the evaporator, consisting of: a 23 ° oblique perforated plate 4 with holes of 2 to 4 mm diameter, with a free hole area of 40% in the upper and middle area 4a , which is designed so that its gas flow at full load remains below the entrainment speed for liquid, and a free hole area ≥ 60% in the lower area 4b through which liquid flows; one opposite the suction nozzle 7 lying, the perforated plate 4 in the flow direction superior baffle 4c , executed in double suction nozzle width with lateral folds, so that at the same time a protected drainage channel direction evaporator jacket 1 forms; and one over the oblique perforated plate 4 arranged U-shaped flow channel 5 made of perforated plate with holes from 2 to 4 mm in diameter, the suction nozzle 7 encloses and extends with 1.4 times Saugstutzenbreite in the axial direction, with its legs to the evaporator jacket 1 and has a free hole area of 40%, which is such that its gas flow at full load remains below the entrainment speed for liquid. Device for separating refrigerant liquid and gas and for returning liquid refrigerant according to claim 1, characterized in that the baffle plate 4c under the oblique perforated plate 4 is attached to its folded lateral legs, an open side facing downwards and the flow channel center is aligned with the Saugstutzenmitte. Device for separating refrigerant liquid and gas and for returning liquid refrigerant according to claim 1, characterized in that the flat perforated plate bottom of the directly under the suction nozzle 7 in the axial direction extending flow channel 5 parallel to the perforated sheet below 4 is arranged and the suction nozzle 7 at right angles to it.

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