FI78176C - FOERFARANDE OCH ANORDNING FOER UTNYTTJANDE AV VAERMEENERGI SOM FRIGOERS I KYLPROCESS. - Google Patents

Description

78176

The present invention relates to a method for utilizing the thermal energy released in the cooling process according to the preamble of claim 1.

The invention also relates to an apparatus for carrying out the method.

Refrigeration processes using ammonia or freon as a medium are commonly used wherever mechanical cooling is required. Combined cooling and heating processes operating in conditions with large temperature differences are practically non-existent. due to technical limitations related to cold processes.

DE patent publication 914,734 describes an apparatus in which compressed air is cooled by expansion turbines. In the equipment, the air compressed by the turbocharger is cooled by a condenser and led to a condensing turbine equipped with a front turbine. There is a radiator between the turbines. The waste heat from the latter turbines is used as additional power for the main engines. The temperature range used is one in which freezing is not possible.

DE-A-1,237,594 describes a refrigeration apparatus in which an outlet pipe for a space to be cooled passes through a cooling turbine in which. the exhaust air in the turbine is expanded, is connected to the primary part of the heat exchanger, which in turn is connected to the compressor, which compensates for the pressure losses of the cooling turbine, the primary part of the heat exchanger and the pipes. In the apparatus, the inlet pipe of the space to be cooled is led through the compressor to the secondary part of the heat exchanger, where it cools to a temperature lower than the space to be cooled. The temperature range used is 10 ... 42aC and in addition the process pressure ratio is very small.

2 78176 SE 3X0 501 describes a cooling method in which part of the cooled and compressed gas is led to a working circuit having a second compression compressor, a second cooling generator, a second cooling turbine and a second cooling load, which may be arranged in a second position relative to the first cooling load. the cooling effect. It is thus a closed helium gas process without any freezing problems.

Traditional refrigeration processes use media that, due to their properties, are generally toxic to the environment and can only be used in a fairly limited temperature range.

If cooling energy is to be used, for example, for the production of domestic hot water, a normal heat pump must be connected after conventional refrigeration machines to achieve the required temperature (above 60 ° C). Such an arrangement complicates the system and reduces the specific energy consumption.

The object of the present invention is to obviate the disadvantages of the technique described above and to provide a completely new type of method for utilizing the thermal energy released in the cooling process.

The method is based on the use of the already known so-called BRAYTON process, which is characterized in that ordinary air is used as the medium. It has the advantage of non-toxicity compared to traditional media.

In the proposed process, the temperature level required for freezing is achieved by allowing high pressure air at a temperature of about 10 ° C to expand in the turbine to normal pressure. With a pressure ratio of 3, a temperature of less than -50 ° C is always reached, depending on the air humidity. The required high-pressure air is made by an uncooled turbocharger. In this way, the pressure 3 78176 always heats up to 200 * C according to the inlet temperature. With the help of heat exchangers, the air is cooled to the inlet temperature required by the turbine, whereby e.g. hot water suitable for heating purposes. Part of the power required by the compressor is obtained from a turbine connected to the same shaft and the rest from an electric or similar motor. The total heat coefficient in this combined cooling and heating process is. class 3.

An essential feature of the process is that the control of the turbine inlet temperature prevents any freezing and shrinkage problems in the turbine impeller due to air humidity.

More specifically, the method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

The device according to the invention, in turn, is characterized by what is set forth in the characterizing part of claim 5.

The invention provides considerable advantages. Thus, by means of the invention, cooling energy can be produced exceptionally efficiently for the purposes of freezing and the like. With the proposed method, the working fluid leaving the cooling object reaches a temperature level that can be used for heating, hot water production, etc.

The main advantages of this method based on the BRAYTON process can be considered the simplicity of the equipment, the non-toxicity of the medium used, the large temperature range that can be achieved and a reasonably good total heat factor.

The invention will now be examined in more detail by means of exemplary embodiments according to the accompanying drawings.

1 78176

Figure 1 shows in part schematic the process according to the invention.

Figure 2 shows the structure of an air turbine suitable for the process according to the invention and the associated temperature or humid air temperature control equipment flowing into the turbine.

Figure 3 shows a cross-section of the turbine impeller as well as a diagram illustrating the actual temperature of the flowing air and the wall temperature of the turbine in the stator and rotor.

According to Figure 1, the apparatus consists of an engine-driven turbocharger engine according to the diagram, heat exchangers located between the compressor and the turbine, a cold chamber or tunnel included in the cooling process, and equipment for temperature control.

In this example case, the process supply air temperature is about 30eC. In the turbocharger 2, when compressed with an efficiency of 82% to a pressure of 3 bar, it reaches a temperature of 170eC in the post-compressor section 3. By heating the raw water from 5eC to 60eC in the heat exchanger 4, the air cools to 40 ° C at a flow rate of 5 kg / s. 8 kg / s. The air is cooled in the heat exchanger 6, for example by the exhaust air of the cold chamber 10, to eliminate freezing problems in the expansion process at 10 ° C 7. In the expansion turbine 8 back to normal pressure, the air cools to -55 ° C at 9, then directed to the cold chamber Air with a temperature of 10eC is used by means of a control damper 11 to cool the supply air of the above-mentioned turbine or alternatively to some other cooling object, e.g. in air conditioning.

The power required by the compressor 2 in the example case is 710 kW, of which the turbine produces 325 kW. The required additional power 5 78176 is obtained from the electric motor M, which must have a power of about 410 kW to compensate for various losses. The heat output from the process in the example case is 650 kW and the cooling output in the cold process is 230 kW. An additional benefit is available from the cold process exhaust air and the ice formed by the air humidity. The minimum heat factor in the example case is about 2.15. The efficiency of the process can be substantially improved if a suitable waste heat source is available to raise the temperature of the supply air 1.

The air turbine suitable for the invention according to Figure 2 consists of the turbine itself and a device for controlling the temperature of the incoming wet or moist air. Figure 2 shows an arrangement with which the control system can in principle be constructed. The incoming air control system 19 is divided into three flow channels, the first (I) being provided with a heating heat exchanger 20, the second (II) with a cooling heat exchanger 21 and the third (III) being a direct through-flow channel without a heat exchanger. The temperature of the incoming air is controlled by controlling the air flow partially or completely through one of the flow ducts I, II provided with the heat exchanger 20, 21 by adjusting the control flaps by either pneumatic, hydraulic or electric actuators 24, 25.

Figure 2 shows the structure of an air turbine. The air flowing into the air turbine is led to a temperature control unit 19, where the air flow can pass through three ducts I, II, III. The air flow temperature is measured after the control unit 19 in the duct 13 leading to the turbine. If the air temperature in the duct 13 is below the desired value, the control flap 22 is opened by the actuator 24, passing part of the incoming air flow through the air flow heat exchanger 20. If the air temperature in the duct 13 is above the desired value, the control flap 23 is opened by means of the actuator 25, whereby part of the incoming air flow passes through the air flow cooling heat exchanger 21 and the incoming air is cooled. The temperature of the incoming air is controlled by known technology.

The air turbine can be structurally either an axial turbine # radial turbine or an intermediate form thereof. The operating principle of the turbine can be an action turbine or a reaction turbine or a turbine operating at a reasonable reaction rate (r = 0.05 ... 0.45). The turbine exemplified in Figures 2 and 3 is an axial turbine operating at a reasonable degree of reaction.

The air turbine consists of a stator 26 with guide vanes 14 associated with the guide wheel 27. The other part of the turbine is a rotor 28 with running vanes 15 connected to the impeller 29. The guide grooves 16 formed between the guide vanes 14 are strongly curved to separate the rather large subcooled water droplets and airflow. disintegrate upon impact on the guide vanes 14 and partially solidify or freeze or form wet snow. Adhesion of ice or wet snow to the guide vanes 14 is prevented so that the wall temperature of the vanes is above the freezing point of the water, whereby snow or ice does not stick to the warm and wet wall but slides along the wall surface and blows away with the air flow.

There is a relatively large gap 12 between the guide wheel 27 and the impeller 29 so that the distance of the air flow from the guide wheel 27 to the impeller 29 is sufficiently long. This is important for the operation of the air turbine because although the airflow temperature has dropped significantly below the freezing point of the water after passing through the guide soles 16, the wet snow and subcooled water droplets must have enough time to freeze , these do not adhere to the walls of the impeller 29, even if the prevailing wall temperature is below the water freezing point of 7 78176, since the dry ice particles do not adhere to the cold wall surface.

The intermediate space 12 is shaped so that two annular vortices (torus) 18 are formed between the guide wheel 27 and the impeller 29 in the air stream to prevent ice formation and adhesion to the turbine walls.

Figure 3 shows the actual temperature of the flowing air as well as the turbine wall temperatures in the stator 26 and the rotor 28 on the cutting axis of the guide and impeller. Examining the figure, the functional idea of the invention becomes clear, in which the aim is to construct an air turbine in which ice formation is prevented in the dangerous temperature range -10 ... 0eC and contact of subcooled water droplets with those walls of the turbine below 0eC.

The temperature of the incoming moist air, shown by the line To in Fig. 3, is adjusted by the control unit 19 so that it is at its desired value above the freezing point of the water. The turbine expansion conditions and reaction rate are chosen so that the turbine wall temperature Ts in all those parts of the stator that are in contact with the air flow is clearly, but only slightly, above the temperature range dangerous for freezing. In this case, the wet snow formed in the stator guide cell 16 when the moist air flow cools, as well as the subcooled water droplets, do not adhere to the stator 26 guide vanes 14 and ice formation detrimental to the flow or hazardous to turbine operation does not occur.

The static air temperature in the space between the guide and impellers, as well as the turbine wall temperature Tr in all parts of the rotor in contact with the air flow, are well below the freezing point to prevent the formed dry ice particles from partially melting on the wall surfaces and allowing ice particles to adhere to the wall.

β 78176

It should be noted that the axial dimension of the intermediate space 12 is at least 30% and preferably about 50% of the axial dimension of the impeller 15 and that the air temperature before the turbine in the channel 13 is in the range 2 ... 10 ° C and the temperature between the impellers 12 is in the range -30 ... -15eC.

The stator does not have to be of the line type, but can also be equipped with nozzles, for example.

In addition to direct freezing in either a chamber or a tunnel, the proposed refrigeration process is suitable for e.g. for freezing the ice rink, condensing ammonia circuits in dairy ice water systems, and cooling the like in closed refrigerant circuits by replacing the cooling chamber 10 with a process cooling coil. Subsequent, still cold exhaust air can often be utilized to cool air-conditioned spaces or appliances and engines that require air cooling.

Depending on the dimensions of the machine, the hot air after the compressor can be used for the production of district heat, space heating in general and / or the production of hot process water, etc., by means of heat exchangers.

The district heating application, combined with e.g. cooling of an artificial ice rink, enables low-cost heat and cooling during low summer heat load typical of summer time, utilizing cheap summer electricity cogeneration. The method could be quite competitive compared to a low-load district heating boiler.

New areas of application for the combined cooling and heating process may be found in hot countries, where cooling is often a vital condition (e.g. large building complexes, hospitals, palaces, etc.) and thermal energy is needed for industrial processes.

Claims (5)

A method for utilizing the thermal energy released during a cooling process, wherein: - humid air utilized as a working medium is measured in a compressor (2), - in the compressor (2), the air is compressed to a higher pressure, a higher pressure of compressed air is cooled to a lower temperature, - the cooled air is conducted to a turhin (8), where the axial extension of a gap (12) equals at least 30% of the axial extension of the running blades (15) and the gap ( 12) is extended in a radial direction beyond the radial extension of the channels (17) between the running blades (15) in order to create a vortex (18) at the inner and the edge of the gap (12) to prevent ice formation , whereby the air is allowed to expand to lower pressure and is cooled in said turbine (8), such a high pressure that des s temperature exceeds the minimum temperature of the boiling point of the water at normal atmospheric pressure, 13 781 76 - the compressed high pressure air is cooled to a sufficiently low temperature, e.g. below 15 ° C, in at least one heat exchanger (4, 6) to prevent freezing of the turbine (8), - heated medium from the secondary circuit of the heat exchanger (4, 6) is used as usual, e.g. and - air cooled below the freezing point of the water in the turbine (8) is routed as usual to the object to be cooled. The method of claim 1 applied to such an air turbine (8), in which the axial extension of the intermediate space (12) extends to at least 30% of the axial extension of the running blades (15) and the space (12) is extended radially. direction beyond the radial extension of the ducts (17) between the running blades (15) in order to create a vortex (18) at the inner and outer edges of the gap (12) to prevent ice formation, characterized in that the air is compressed in the compressor (2) up to a pressure of between 2.5 and 3.3 bar, preferably to a pressure of 3.0 bar. Process according to claim 1 or 2, characterized in that the air compressed in the compressor (2) is cooled in two cooling stages before the turbine (8). Method according to claim 3, characterized in that the air is cooled in the first stage by water circulating in the secondary circuit of the heat exchanger (4) and in the second stage of return air from the cooled article (10) circulating in the second heat exchanger (6). secondary circuit. An apparatus for utilizing thermal energy released by a cooling process, comprising