The present invention relates to a factory plant and a machine or machine plant for the processing of foodstuffs. Foodstuffs are normally processed by means of electro-motor driven, permanently installed machines (machine plant) , such as meat mincers, mixers, conveyors, etc. In order to inhibit the growth of micro-organisms, the processing often takes place in refrigerated rooms. However, the electric motors give off heat to the air. This waste heat is removed by means of large ventilating and refrigerating plants, which exhaust heated air from and inject cooled air into the rooms. The heat involved is often considerable. A realistic example is a conveyor plant in the slaughtery sector with 175 electro-motors, giving off 55 kW of heat.

For the persons working in the refrigerated rooms, the injection of cooled air may be quite uncomfortable. The large ventilating and refrigerating plants are also expens¬ ive to install and to run. Relatively large volumes of air have to be moved to obtain the desired cooling, which requires large ducting cross sections and heat exchanger surfaces, because the flow velocity cannot be increased without limits when energy consumption, work environment, and noise generation have to be considered.

Seen in relation to the known technology it is the object of the invention to indicate a factory plant for processing foodstuffs, where the air temperature in refrigerated rooms with motor-driven machines can be maintained at the same level as hitherto, but by less costly means. It is also an object of the invention to indicate a motor-driven machine or machine plant for the processing of foodstuffs in a refrigerated room, which with the same mechanical operating power as hitherto gives off lower heat load to the room than hitherto known machines or plant.

The object is achieved as indicated in claims 1 and 11 by inserting in at least one driving motor a water-driven hydraulic motor in a water supply circuit, which can remove heat from the room.

This solution involves that a large part of the heat from the power loss of the motor can be absorbed by the water driving the motor. Water is far better suited for trans¬ porting heat than air, because the heat capacity is approx. 4.18 kj/(kg K) , and its density is approx. 0.001293 kg/1. Therefore a heat load of 55 kW can be removed by a heating a water flow of approx. 1.32 1/s by 10 K, whereas the required air flow at the same heating rate amounts to approx. 4250 1/s, or approx. 4.25 m ³ /s. Displacement and cooling or conducting away a water flow of approx. 1.3 1/s can be effected by considerably simpler and cheaper means than by displacing or cooling or conducting away an air current of 4.25 m ³ /s.

The required water flow can be handled with tubes of the same dimensions as used for normal water supply. The sol¬ ution improves the working environment, because the injec¬ tion of cold air can be reduced considerably. By using water as the driving medium, also the risk of pollution is avoided, which would be involved with an oil-driven hydrau¬ lic motor.

According to requirements, the advantages involved in the invention can be exploited to varying degrees. The heat loading of the air from one or several motors can be mini¬ mized by feeding it or them with water, whose temperature is under the temperature in the refrigerated room, cf. claims 2 and 12. However, this involves a certain inconven¬ ience with condensation on and dripping from the water pipes and the motor or motors.

When replacing machinery plant in existing buildings the aim may be an increase of the mechanical output of the machinery plant without increasing the requirement to ventilation. This can be achieved by conducting away with the water the part of the heat that exceeds the heat release of the former machinery plant. Such a solution is characterised in claims 3 and 13.

Where condensation and dripping must be avoided, the feed water can be given the same temperature as the ambient air or a higher temperature, whereby a certain heat transfer from the motor and its supply lines to the air is lost, but at the same time a large proportion of the heat waste of the motor is still removed from the refrigerated room with the water, cf. claims 4 and 14.

If this solution is chosen, the heat release to the refrig¬ erated room can be reduced by heat insulating the piping of the water supply circuit, cf. claims 5 and 15. It is even possible to heat insulate the hydraulic motor itself, cf. claims 6 and 16. By contrast, the hitherto currently used electro-motors are air-cooled, which impedes heat insula¬ tion.

As indicated in claims 7 and 17, the water supply circuit may be a closed circuit, which is arranged to give off the waste heat outside the refrigerated room. Essential elements of such a closed circuit is a tank, serving as reservoir for the circulating water, and an electro-motor driven pump, which creates the pressure required for driv¬ ing the hydraulic motor. The tank, pump, and electro-motor are at the same time the principal heat sources in such a circuit. In many cases it is possible to obtain sufficient heat release from the circuit just by placing these three elements outside the refrigerated room, cf. claims 8 and 18.

If required, it is possible to obtain improved cooling of the water supply circuit by providing it with a heat exchanger, cf. claims 9 and 19. A quite different possibil¬ ity consists in using an open water supply circuit, where the heat absorbed from the motor is taken out with the water through an outlet from the refrigerated room, cf. claims 10 and 20.

The present invention is described and explained in more detail in the following, where two preferred embodiments are reviewed with reference to the attached drawings.

Fig. 1 shows a conventional foodstuff factory with a conventional, electro-motor driven machinery plant in a refrigerated room.

Fig. 2 shows diagrammatically a foodstuff fac¬ tory according to the present invention, with a water-hydraulically driven machine plant in a refrigerated room.

Fig. 3 shows diagrammatically a foodstuff fac¬ tory as in fig. 2, but with an open water supply circuit for the machinery plant.

In a conventional foodstuff factory 1 according to fig. 1, foodstuffs are processed in a refrigerated room 2. The processing takes place by means of machinery plant 3, which may be a conveyor plant driven by one or several electro¬ motors 4 with a reduction gearing 5. The electro-motor 4 and the reduction gearing 5 give off heat to the ambient air, and this heat is removed from the refrigerated room by means of refrigerating plant 6.

The refrigerating plant is shown diagrammatically as a conventional, mechanical cooling plant with a compressor 7,

a condenser 8, an automatic expansion valve 9 with tempera¬ ture sensor 10 and an evaporator 11. In the cooling plant a refrigerating medium circulates, which by evaporation in the evaporator 11 absorbs heat from the room 2 under low pressure. The evaporated refrigerating medium is compressed by the compressor 7, giving off the absorbed heat in the condenser 8 at high pressure, whereby the refrigerating medium is condensed. Subsequently, the pressure of the refrigerating medium is reduced again when passing through the reduction valve 9 to the pressure level of the evapor¬ ator. The filling with refrigerating medium of the evapor¬ ator is controlled via the expansion valve 9 by the sensor 10.

A typical power balance for the machinery plant of the factory is diagrammatically illustrated in fig. 1 with various arrows, showing the distribution of the absorbed operating power, and thereby the energy consumption, in the various parts of the plant. It must be pointed out that this balance considers only the power that must be used regarding the machinery plant. Other sources of power consumption, such as the required refrigerating power for keeping the refrigerated room refrigerated in relation to the surroundings, and for removing the heat released there- to by lighting equipment, personnel, heat treatment plant, raw materials, etc., have not been included in this power balance.

Out of the total power consumption 20, which is set at 100 percent, 84 percent is spent, arrow 21, on operating the machinery plant 3 via electro-motor 4 and gearing 5. Part of this operating power 21 is converted into mechanical power 22, which accounts for 39 percent of the total power consumption 20 of the factory. The balance of the power consumption 21 of the machinery plant is converted into machine heat 23, which is emitted to the ambient air in the

refrigerated room 2. The machine heat 23 accounts for 45 percent of the total power consumption 20.

In order to have this machine heat 23 removed from the room 2 by the refrigerating plant 6, the compressor 7 must be supplied with a refrigerating power 24, which amounts to 16 percent of the total power consumption 20 of the factory. The total waste heat power 25 from the machinery plant of the factory, which is composed of the machine heat 23 and the cooling power 24, thereby amounts to 61 percent of the total power consumption 20 of the factory to machine power.

In fig. 2 the machinery plant 3 is driven by a water-driven hydraulic motor 30. The hydraulic motor 30 is inserted in a water supply circuit 40. The circuit 40 is a closed cir¬ cuit, where by a pump 42, water from a tank 41 is pumped to the motor 30 via a supply pipe 43. A return pipe 44 from the motor 30 takes the water to a cooler 45. In the cooler

45, the heat is given off from the return water to a cool- ing circuit, which may contain an air-cooled heat exchanger

46. The cooling circuit may also be an open cooling water circuit with an inlet and an outlet. The return water flows on to the tank 41 via a tank pipe 49. Between the tank 41 and rest of the supply circuit, filters 47 are inserted.

The pump output pressure, that is the pressure in the supply pipe 43, is maintained at a suitable value by an overflow valve 48, which is inserted between the supply pipe 43 and the tank pipe 49.

In fig. 2, out of the total power consumption 20 of the factory, a 80 percent share, arrow 21, goes to operation of the machinery plant 3 via the water-driven hydraulic motor 30. In the hydraulic motor a larger part of the supplied operating power 21 can be converted into mechanical power 22, than is the case in an electro-motor. In this case the

mechanical power 22 amounts to 65 percent of the total power consumption 20 of the factory.

The balance of the power consumption 21 of the machinery plant is converted into machine heat 23, which is trans- ported out of the refrigerated room 2 by the water in the return pipe 44. In this case the machine heat 23 amounts to 15 percent of the total power consumption 20.

The hydraulic circuit of the machinery plant 3 gives off very little heat to the refrigerated room, because typical¬ ly the circulating water can be kept at a low temperature, for example below 40°C. It is also possible to heat insu¬ late the supply pipes of the motor in the room, as well as the motor itself, in order to further reduce the heat load. The heat power given off to the refrigerated room 2 is therefore set to be 0. Thereby no heat transmission takes place from here, and consequently there is no power con¬ sumption in the cooling plant 6. Of course the refrigerat¬ ing plant is still required on account of the other heat sources, cf. the introductory remark on energy balance in fig. 1.

The machine heat 23 is taken to the heat exchanger 46 by the circulating water, and the heat exchanger gives off both the machine heat and the power loss, which is trans¬ formed into heat in the water supply circuit 40, to the ambient air in the factory. At water-hydraulic operation of the machines, the total waste heat power 25 from the machine plant of the factory, which is composed of the machine heat 23 and the power loss in the hydraulic circuit 40, amounts to 35 percent of the total power consumption 20 of the factory to machine operation, and thereby to far less than at electro-motor operation of the machines.

In the example in fig. 3 the machinery plant 3 is similarly driven by a water-driven hydraulic motor 30, which is inserted in a water supply circuit 50. The circuit 50 is an

open circuit, where water from an external supply pipe 51 is taken to the tank 41 via a filter 52. The pump 42 pumps water to the motor 30 via a supply pipe 43. From the motor the water is taken to an outlet 53, which is taken out of the room 2. The output pressure of the pump, that is the pressure in the inlet 43, is maintained at a suitable value by an overflow valve 48, which is inserted between the inlet 43 and a tank pipe 49. Between the tank 41 and the rest of the supply circuit, filters 47 are inserted.

Like in the example above, fig. 2, a proportion of 80 percent, arrow 21, of the total power consumption 20 of the factory is spent on operation of the machinery plant 3 via the water-driven hydraulic motor 30. Similarly, the mechan- ical output 22 of the motor amounts to 65 percent of the total power consumption 20. The balance of the power con¬ sumption, the machine heat 23, is taken out of the refrig¬ erated room 2 by the water in the outlet 53. Like in fig. 2, the machine heat 23 amounts to 15 percent of the total power consumption 20.

Regarding the refrigerating plant 6 the same considerations apply as set forth in connection with fig. 2. Of course, there is still the power loss in the hydraulic circuit 50 to take into account, which is transformed into heat and given off to the ambient air in the factory. Therefore it is only the waste heat 25 from the supply circuit 50 that must be ventilated out of the factory, and this waste heat amounts to only 20 percent of the total power consumption 20 of the factory 20 to machine operation.

Therefore, an open hydraulic circuit results in even more favourable energy conditions than a closed circuit.

The figures given as examples in fig. 2 and fig. 3 rely on the assumption that any power losses from the hydraulic motor 30 are led away with the water. However, a pro-

fessional will easily see that it is possible to allow for a certain heat emission from the motor and its supply elements into the room 2, and still obtain a saving in energy in relation to electro-motor operation.