IE911207A1 - Refrigerating plant - Google Patents

Abstract

A plant for processing cold water and brine contains, in a gastight housing (12), at least one coolant circuit (38) which is in heat-exchange contact with a cold water/brine circuit (58, 60) or a cooling water/brine circuit (62, 64), which consists of an evaporator (40), a compressor (46) and a liquefier (42) and which contains NH3, and a cooler (80) which is connected to the cooling water or brine circuit (64) in the housing (12) to remove the heat loss occurring in the housing (12). Situated near the upper boundary (82) of the housing (12) is a spraying device (84) and in the region of the lower boundary (24) of the housing (12) a collection zone (26). The housing (12) is provided with gastight connections (58, 60, 62, 64, 86, 30) taken to the outside for the cold water or brine circuit, the cooling water supply of the liquefier, the water supply of the spraying device and the liquid drain from the collection zone (26), and with gastight connections for the electrical energy supply or for transmitting the signals from the control, regulation and monitoring devices (134, 136, 138) required.

Description

Refrigerating Plant BACKGROUND OF THE INVENTION The invention relates to refrigerating plant using a secondary cooling medium, such as brine or cold water, in a secondary medium circuit, comprising at least one refrigerant circuit which is in heat exchanging relationship with said secondary cooling medium circuit, and is made up of an evaporator, of a compressor and of a condenser containing, said refrigerant being in the form of ammonia.

Herein the term brine is used to include antifrost 10 solutions as well as brine in the restricted sense.

Many installations using a secondary cooling medium such as cold as water or brine are operated with fluorinated hydrocarbons as a refrigerant in the refrigerant circuit, although such use is environmentally undesirable. Ammonia may also be used as a refrigerant and it is in fact superior from the point of view of effective use of energy hut owing to its hazardous properties for humans is subject to considerable restrictions, For this reason plant run using ammonia and containing more than a certain quantity thereof is not permitted in residential areas, or for that matter in other applications such as many supermarkets and restaurants. SHORT SUMMARY OF THE PRESENT INVENTION.

Accordingly one object of the present invention is to provide a cold water and brine handling plant of the initially described type which is so improved that despite the use of ammonia as a refrigerant, it may be employed universally, as for instance in buildings or outdoors, and for this purpose is securely sealed off from the outside in a highly effective manner to prevent any escape of ammonia.

A further object of the invention is to provide such plant capable of use at temperatures of the brine or other secondary cooling medium between - 40° C and + 20° C.

In order to achieve these or other objects appearing from the present specification, claims and drawings, in the present invention the at least one refrigerant circuit is arranged in a gas-tight housing, in which a cooler for the heat dissipated in the housing is connected with the secondary cooling medium circuit, and near the upper wall of the housing a sprinkler device is provided in the latter and near the lower wall of the housing a runout zone is provided, and the housing is provided with connections, extending through a wall of the housing in sealing manner, for the secondary cooling medium circuit, the coolant water supply for the condenser, the ι· Her supply for the sprinkler device and for the draining of liquid from the runout zone, and with gas-tight connections for the supply of electrical power and for the means conducting signals in connection with the necessary control, automatic control and monitoring devices.

Owing to the hermetic encapsulation of the parts of the plant comprising Hie refrigerant circuit it is possible to ensure that any leaked ammonia is not able to escape into the atmosphere and the area around the plant accessible to personnel. Any ammonia which is set free in the interior of the housing can he absorbed by the sprinkler' device as ammonia solution and deposited in the runout zone whence it is drained into suitable containers placed 3D without the housing.

Owing to the hermetic sealing of the housing the cooler ensures that the heat dissipated in the housing is conducted to the outside, the connection of the cooler with the secondary cooling medium circuit within the housing making it possible to have only a IE 921207 kJ small number of lines or ducts which extend in a sealing manner through the housing wall.

In order to ensure that when there is any leakage the amount of ammonia collecting in the housing or escaping into the surroundings is not large enough to be hazardous, it is possible to adopt advantageous further features of the invention involving the provision of a plurality of mutually independent monitoring devices, a first system of this type providing a low gage pressure in the housing and of a pressure monitoring means in the housing, which is such that when a lower or an upper limiting value is no longer complied with the coolant circuit is switched off and the sprinkler device is turned on.

Prior to putting the plant into operation the gage pressure is set to the desired value and owing to the gas-tight design of the housing is kept unchanged unless a defect should occur. If the pressure should no longer comply with the upper limiting value this will indicate that the internal pressure in the housing is increasing, something that may be due to ammonia leakage. If the lower value is no longer complied with, this will mean that the gage pressure in the housing is falling so that it may be concluded that there is a leak in the housing. In either case the compressor and thus the coolant circuit may he turned off and any ammonia present in the housing rnay precipitate as ammonia solution and drain away.

In accordance with a further possible safety measure of the invention there is a device for monitoring the liquid level in the condenser, which is adapted to switch off the coolant circuit, if a given lower liquid limiting level is no longer complied with (i. e. is gone below), and to switch on the sprinkler device. A drop of the liquid level ι dll indicate that there is a loss of ammonia in the closed refrigerant circuit so that it may be concluded that there has been an escape of ammonia into the interior of the housing.

In accordance with a furihet advantageous development of IE 921207 the invention an ammonia sensor is located in the housing, which is adapted to turn off the coolant circuit when it detects ammonia and to turn on the sprinkler device. In the case of this design the presence of ammonia is detected directly and not indirectly, as in the other examples described using secondary data.

In keeping with yet another possible form of the invention sensors are arranged in the secondary cooling medium circuit outside the housing in order to measure the electrical conductivity of the secondary cooling medium, such sensors being adapted to turn off the coolant circuit when an upper limiting value related to the presence of ammonia is not longer complied with and to turn on the sprinkler device. This form of the invention is based on the fact that the conductivity of the medium in the circuit drops when ammonia is mixeO with it, this again being an indication of the occurrence of a leak through which the ammonia does not find its way into the interior of the housing hut leaves the safety area formed by the housing via the secondary cooling medium circuit, albeit in a closed circuit. In order to facilitate the design of the housing in a gas-tight manner and in order to avoid the danger of explosions, in accordance with a further advantageous feature of the invention the; control, automatic control and monitoring devices are designed using sensor technology.

In accordance with a further possible and particularly advantageous development of the invention the devices arranged outside the housing for electrical power supply and foi control, automatic control and monitoring are arranged together in a switchgear cabinet and are connected via a central interface on the housing with the devices associated with them and placet! in the housing therewith. This leads to a compact design of ttie plant in a modular system, which makes possible particularly economic adaptation to suit the respective application.

In accordance with another advantageous form of the invention the reiiigerant circuit is provided with a filling and emptying line, which is provided with a connection pipe for IE 921207 coupling with an extension line, such connection pipe being provided adjacent to an inspection opening, which may be closed in a gas-tight manner. It is using this extension line that it is possible to completely drain the refrigerant circuit if this is necessary; but it is also possible for it to be filled without the wall of the housing having to be opened during operation of the plant It is preferred for a pressure safety valve to be arranged between the condenser and the evaporator so that the gage pressure from the condenser may be let off to the evaporator.

Both as regards optimizing the energy requirement and also from the point of view of safety, a further feature of the invention may be employed in accordance with which a plurality of individual cooling medium circuits are arranged in the housing J 5 which are able In be turned on and off.

In order to ensure that any leakage of ammonia into the housing is not able to cause damage to the drive motors of the compressors, as for instance to the bearings or to the windings thereof, in accor dance with a preferred fonn of the invention electric drive motors in the interior of the housing are separately encapsulated. The use of aluminum wire windings is a further method of precluding trouble in this respect.

A further expedient form of the invention particularly useful in connection with a modular design is one in which the connections for I lie supply and return to and fi oin the secondar y medium cooling medium circuit associated with the condenser and for the return and supply to and from a secondary cold medium circuit associated with the evaporator are mounted together on the wall of the housing in a connection zone and a connection unit is associated with the connection zone, such unit being so arranged that between a connection point, associated with the connection zone and a connection point leading to other parts of the equipment, the said connection unit has the supply and return parts for the secondary cooling medium circuit and of the secondary cold IE 921207 medium circuit extending through it and contains the pumps for the feeding both these secondary circuits, and as part of a further advantageous feature of the present invention the connection unit comprises two-way valves, which are adapted to connect the return lines of these two circuits selectively with the condenser or, respectively, with the evaporator or, via a connection serving for free cooling, with the feed line of the respective other one of these two circuits so that when the outside temperature is lower than the device to be cooled the drive energy for the refrigerant circuit may saved.

It is preferred for the connection unit to be a stand alone unit which may be entered for purposes of inspection. Furthermore it is possible for the connection unit to be adapted for the mounting thereon or therein of the switchgear cabinet.

The invention will now be described in more detail with reference to the working embodiment thereof shown in the drawing.

DETAILED ACCOUNT OF WORKING EXAMPLE OF THE INVENTION.

The single figure of the drawing shows a diagrammatic vertical ection taken through a plant designed in accordance with the invention for the cooling the cold water or brine in a secodary circuit.

The plant is constructed modularly and is arranged on a main frame genet Jly referenced 10: it comprises three main parts, that is to say a bousing 12 enclosing the ammonia zone, a connection unit l-1 and a switchgear cabinet lo.

The said housing 12 consists of a lower part 12a and a removable upper [tart 12b able to be connected in a gas-tight manner with the lower part 12a with a parting plane IB therebetween. In the lower part 12a there are furthermore inspection openings 22 which are able to be shut off by gas-tight covers 20. On the bottom 24 of the tower part 10a there is a trough-like runout zone 26, which at its lowest point is provided with a draw off connection pipe 3i) shut off by a gas-tight shut off valve 2fi, hy way of which using an externally placed drain pump 32 liquid, IE 921207 ammonia or ammonia solution may be drawn off through a line 34 to a transport containers 36.

The housing 12 shuts off the refrigerant circuit 38 hermetically. The circuit consists of an evaporator 40, a condenser 42 and compressor 46 associated with an electric motor 44 for driving it, said compressor being placed in the line 48 between the evaporator 40 and the condenser 42, a line 50 returning the refrigerant from the condenser 42 to the evaporator 40, said line 50 having an expansion device 52 thereon, and of an excess pressure line 54 between the condenser 42 and the evaporator 40 with an excess pressure valve 56.

The evaporator 40 is provided with a feed connection 58 and a return connection 60 for the cold secondary medium (water or brine) to be cooled and in the same manner the condenser is provided with a Feed connection 62 and a return connection 64 for secondary cooling medium. These connections extend in a gas-tight manner through a side wall 66 of the lower part 12a of the container 12 to the outside and are prepared for connection with short pipes, which are associated with them, 68, 70, 72 74 in the connection unit 14.

In order to fill and empty the refrigerant circuit 38 there is a pipe connector 76 mounted on the evaporator 40 and this pipe connector comes to an end in the vicinity of an inspection hatch 22 within the housing 12 rand at its end provided with a shut off valve 78 is prepared for connection with a filling and emptying line.

Between the return connection 64 opening into the condenser 42, for the secondary cooling medium and the corresponding feed connection 62 there is a cooler 80 which is arranged within the housing 12 and over the condenser 42, such cooler 80 serving for removal of heat dissipated within the hermetically sealed housing 12.

Adjacent to the upper wall 82 of the housing 12 the housing contains a sprinkling device 84, which is able to he connected, via a line extending in a gas-tight manner out of the housing 12, with IE 921207 a water connection 88. For this purpose there is a solenoid valve 90 actuated by safety devices to be described in more detail infra, or a manually operated shut off valve 92 arranged in the bypass.

In the drawing the line 86 will be seen on the left extending out of the housing 12 in order to make the figure more straightforward. However, in practice it may well turn out to he more expedient to arrange for this line 86 as well to extend into the connection unit 14.

A connection pipe 96 having a shut off valve 94 is arranged 10 on the housing 12 and it serves to maintain a certain low gage pressure serving for control purposes in the housing 12 after being restored to its gas-tight state or, respectively, prior to putting into service, after the housiing 12 has been opened and then closed again.

As shown in the drawing in the form of broken lines, in lieu of a single refrigerant circuit 38 in the housing 12 it would also be possible to have a plurality thereof, as for instance, three refrigerant circuits, which are indicated by symbols in the form of the additional compressors 46' and 46. Then in this case in the event of failure of one refrigerant circuit it is possible for the two other circuits to be used to maintain operation. Furthermore, the energy requirement may he more satisfactorily adapted to the respective cooling action needed.

The fitting of the refrigerant circuit 38 or of the refrigerant circuits within the housing 12 with evaporators, compressors and condensers will be in accordance with the power range applying. Despite different sizes of the refrigerating equipment accommodated in the housing 12, the connections issuing from the housing may always be grouped together in a connection zone with the same arrangement, such arrangement being opposite to the lines leading to other parts of the plant and placed in the similar arrangement 14 so that if required on the one hand different combinations of housings 12 for different power ranges and/or line cross sections and connection units 14 on the other IE 921207 hand are possible.

In the same manner a standardized form of the size of the connections at the connection unit 14 and at the switchgear cabinet 16 may facilitate; the manufacture of the plant in the form of a modular system.

The feed connection 58, which is connected with the evaporator 40, for the cold water is continued in the connection unit 14 as a line part 158, which includes two pumping units, able to be selectively operated and placed in parallel to each other, such units comprising in each case a pump 106 and, respectively, 106' placed between two shut off valves 102 and 104 and, respectively, 102' and 104' and furthermore a flap-type check valve 108 and, respectively, 108' also between them. A connection 110 is provided on the side, remote from the connection unit 14 for the conduction of the cold water to other parts of the plant. The cold water returning from the load which is cooled or refrigerated passes via a connection 112 hack into the connection unit 14 and then passes via a line 160 in to the return connection 60 arranged in the housing 12. In the same manner the cooling water feed connection 62 connected with the condenser 42 is continued as a line section 162, which also comprises two parallel pumping sections with shut off valves 114 and 116 and, respectively, 114' and 116', a pump 118 and, respectively, 118' and also a flap-type check valve 120 and, respectively, 120' and comes to an end at a connection 122 on the side 15 of the connection unit. The cooling water returning from a suitable cooling unit passes via a connection 124 h.«ck into the connection unit 14 and is transferred via a line 164 to the return connection 64 in the housing 12.

In the event of the outside temperature being lower than the desired temperature of the device to be cooled then via a three-way valve 130 in the line 160 the cold water returned from the load or, respectively, the secondary medium returning is passed via a connecting line 132 to the line 162 and thence passes via the connection 122 to the external refrigerating or cooling device, not IE 921207 shown. Thence the cold water or, respectively, the brine flows via the connection 124 into the line 164 as far as a three-way valve 134, which causes the cooled cold water to flow via a connection line 136 to the line 158, whence it passes via one of the pumps in the line 158 to the connection 110 and thence further to a load to be cooled, not shown.

In order to prevent leakage of ammonia from the plant means are provided both for monitoring the possible penetration of ammonia into the interior of the housing 12 and also the possible penetration of ammonia into the cold and cooling water circuits running out of the housing 12. In this respect safety is increased by the provision of a plurality of independent monitoring or detecting means.

A direct monitoring means is located in the interior of the housing 12 in the form of an ammonia sensor 134.

The plant is furthermore provided with a pressure monitoring device 136 in the housing 12, such device being adapted to detect departures from the internal pressure value in the container 12 set via the connection pipe 96. If the pressure should be higher, this will indicate that ammonia has leaked from the refrigerant circuit 38 into the space enclosed within the housing 12. If the pressure is less than the set gage pressure value of, for instance 0.1 bar, it follows that the container 12 is losing pressure through a leak and the safety standards are not longer being complied with.

A monitoring unit 138 is arranged on the condenser 42 in order to monitor the liquid level therein. In the event of the liquid level falling, this will indicate that the refrigerant is escaping from the refrigerant circuit 38.

In the cold water circuit there is a device 140 and in the cooling water circuit there is a similar device 142 for monitoring the electrical conductivity of the fluid in the circuit. Since the electrical conductivity of the fluid changes when ammonia is present therein, a departure of the readings will lead to the IE 921207 conclusion that there has been an escape of ammonia from the refrigerant circuit 30 into one of the circuits leading out of the housing 12.

In the event of the monitoring devices, which are designed 5 using sensor technology and are connected via electrical connections, not shown, with a computerized switching and automatic controlling device in the switchgear cabinet 16 therein, should indicating a trouble condition, the refrigerant circuit is stopped by switching off the compressor 46 and the solenoid valve 90 is operated so that: the sprinkler device is put into operation and the ammonia in the interior of the housing is precipitated into the runout zone 26, where - as already described - it is able to be pumped into the transport container 36. Using the computer it is possible to set a hierarchy of priorities of the error messages and to cause suitably selected restorative measures to be taken.

The plan!, is furthermore equipped with additional monitoring, automatic control and regulating means as required the operation, examples of such instrumentalities being a thermostat to prevent freezing, a pressure limiter, a thermally responsive overcurrent protection switch, an automatic starting device for use when the line current is restored after a failure, a device monitoring the flow of cold water, a device for registering the number of hours the plant is in operation, a motor temperature indicator and the like, which are connected with the respective devices in the cabinet 16 containing the switchgear. In this respect there is also the possibility of storing all times at which servicing is due in the computer with a suitable timing and emphasis and in lids manner to set the servicing intervals in an economic in a way dependent on the time of operation so that the servicing may be performed at set time intervals.

Claims (16)

1. In refrigerating plant adapted to use a secondarycooling medium in a secondary medium circuit, comprising at least one refrigerant circuit which is in heat exchanging relationship with said secondary cooling medium circuit, and is made up of an evaporator, of a compressor and of a condenser containing, said refrigerant being in the form of ammonia, the improvement residing in the provision of - a gas-tight housing in which the at least one refrigerant circuit is enclosed, said housing further enclosing a cooler for the heat dissipated in the housing, said cooler being connected with the secondary medium circuit - a sprinkler device located near an upper wall of the said housing in the latter, - a means defining a runout zone near a lower wall of the housing, - connections, extending through a wall of the housing in a sealing manner, for the secondary cooling medium circuit., a secondary medium supply for the condenser, a water supply for the sprinkler device and a line for draining of liquid from the runout zone, and - gas-tight connections associated with the housing for the supply of electrical power and for the means conducting signals in connection with control, automatic control and monitoring devices.

2. Plant as claimed in claim 1 wherein a minor gage pressure is maintained in said housing and a pressure monitoring device is provided in said housing, which when said pressure is outside a range between an upper and a lower limit is adapted to turn off said secondary refrigerant circuit and to turn on said sprinkler device. IE 921207

3. Plant as claimed in claim 1, comprising a device for monitoring a liquid level in said condenser and to turn off same when said level is below a lower limit therefor and to turn on said sprinkler device.

4. Plant as claimed in claim 1, comprising an ammonia sensor in said housing, said sensor being adapted to turn off said secondary refrigerant circuit and to turn on said sprinkler device.

5. Plant as claimed in claim 1, comprising sensors for measuring the electrical conductivity of secondary medium in said secondary cooling medium and arranged outside said housing and said sensors being adapted to respond to a limit value related to the presence of ammonia by turning off said secondary circuit and by turning on said sprinkler device.

6. Plant as claimed in claim 1, wherein said control, automatic control and monitoring devices are designed using sensor technology.

7. Plant as claimed in claim 1, wherein devices located outside said housing for electrical power supply and for control, automatic control and monitoring of the parts of the plant, in the housing are arranged together in a switchgear cabinet and are arranged to be connected via a central interface on the housing with the said plant parts associated with them in the housing.

8. Plant as claimed in claim 1, comprising a filling and emptying line forming part of said refrigerant circuit, said line being arranged that in the vicinity of a gas-tight inspection opening arranged in the housing and being provided with a connection pipe for a connection with a line extension.

9. Plant as claimed in claim 1, comprising a pressure IE 921207 safety device so arranged between the condenser and the evaporator that excess pressure directed from the condenser to the evaporator may be let off.

10. Plant as claimed in claim 1 comprising a plurality of secondary cooling medium circuits in said housing which are able to be separately put into and out of operation.

11. Plant as claimed in claim 1, wherein drive electric motors in an inner space in said, housing are separately encapsulated.

12. Plant as claimed in claim 1, wherein connections for the supply and return of cooling water to and from a secondary circuit associated with the condenser and for the supply and return of cooling medium to and from a secondary cold medium associated with the evaporator are arranged adjacently in a connection zone on the housing wall and a connection unit is associated with this connection zone, such connection unit being so arranged that between a connection point associated with the connection zone and a connection point leading to further parts of the plant such connection unit is traversed by the supply and return means of the secondary cooling medium and of the secondary cold medium and comprises pumps for the supply both to the secondary cooling medium circuit and to the secondary cold medium circuit.

13. Plant as claimed in claim 12, wherein said connection unit comprises two-way valves, which art adapted to connect the return lines of such two circuits selectively with the condenser and, respectively, the evaporator or via connection serving for free cooling with the supply line of the respective other one of these two circuits.

14. Plant as claimed in claim 12, wherein the connection IE 921207

15. Unit is in the form of a unit able to be entered by an inspecting person and able to be separately erected. 15 Plant as claimed in claim 12, wherein devices located outside said housing for electrical power supply and for control, automatic control and monitoring of the parts of the plant in the housing are arranged together in a switchgear cabinet and are arranged to be connected via a central interface on the housing with the said plant parts associated with them in the housing and wherein the connection unit is adapted for the mounting thereon or therein of the switchgear cabinet.

16. A refrigerating plant according to any preceding claim substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings .