ES2909205T3 - Device for safe service intervention for a casing and procedure for opening a casing - Google Patents

Abstract

Device for safe service intervention for a housing in which a flammable working fluid of a left-hand cyclic process is located, where - the housing (6) has a gas passage open to the environment, protected by an adsorbent (12) for the working fluid, - the housing (6) has a service opening (14) which, by means of an unlocking device (16), is protected against opening, - the service opening (14) has a connection (15 ) service for a service cartridge (13), - the service cartridge (13) contains an inert gas under pressure in an amount that, in the expanded state, corresponds at least to the volume of the container (6), - the cartridge (13) has a cartridge neck (19) with a connection line (24) in the cartridge neck (19) and an external thread (25) in the cartridge neck (19), - the connection (15) ) service has an internal thread (26) that coincides with the external thread (25) of the cartridge neck (19), - the service connection (15) has a closing cover (21), - comprising the cover (21 ) sealing seal (20) directed towards the outer side of the housing (6), - in addition, a sealing membrane (23) directed towards the inner side of the housing (6), on which a pin (22) towards the outer side of the housing (6), - in addition, a sealing surface (27) on the internal thread (26).

Description

DESCRIPTION

Device for safe service intervention for a casing and procedure for opening a casing

The invention relates to irregular states in refrigeration circuits in which a working fluid acting as a refrigerant is conducted in a thermodynamic cyclic process, such as the Clausius-Rankine cycle. These are mainly heat pumps, air conditioning systems and refrigeration devices, such as those that are usual in residential buildings. In this context, residential buildings should be understood as private homes, rental house complexes, hospitals, hotel complexes, restaurants, and mixed residential and commercial buildings in which people live and work permanently, as opposed to mobile devices, such as air conditioning systems of automobiles or transport boxes, or also industrial systems or medical devices. What these cyclic processes have in common is that they use energy to generate useful heat or cold and form heat transfer systems.

The thermodynamic cyclic processes used have been known for a long time, as well as the safety problems that can arise in the use of suitable working fluids. Apart from water, the most familiar working fluids of the past are flammable and toxic. In the last century they led to the development of safety coolants, which consisted of fluorinated hydrocarbons. However, it turned out that these safety refrigerants damage the ozone layer, lead to global warming, and their safety-related harmlessness led to design oversights. Up to 70% of the turnover corresponded to the need to refill leaking systems and their losses due to leaks, which was accepted as long as it was considered economically justifiable in each individual case and promoted the need to purchase spare parts.

For this reason, the use of these refrigerants has been subject to restrictions, for example, in the European Union through the regulation on fluorinated gases (EU) 517/2014.

It is therefore extremely problematic, on the one hand, to adopt the design principles for thermodynamic processes carrying refrigerants that seem to have proven themselves with safety refrigerants and, on the other hand, to rely on system concepts prior to introduction of safety refrigerants. This is also due to the fact that individual devices have in the meantime become complex systems, which has multiplied the number of possibilities for failures and their consequences. This results, for example, in the following requirements for the security concept:

- In normal operation, the system must be absolutely sealed.

- Neither in the case of a leak in the condenser nor in the case of a leak in the liquefier, the working fluid cannot enter the coupled useful heat or useful cold circuit.

- No working fluid must be able to escape unnoticed from the cooling circuit.

- In the compressor, the working fluid must not escape through the housing.

- In the expansion system, the working fluid must not diffuse through the valve seat or cause cavitation leaks.

- Encapsulated parts must remain accessible for maintenance and inspection purposes.

- In emergencies, there should be no danger.

- The system must be able to integrate into existing spaces.

- The refrigerant must be able to be emptied and recharged.

The concept of emergency must be widely considered. Blackouts, earthquakes, landslides, floods, fires, technical errors and extreme weather conditions are conceivable. Whenever systems are operated on a network, a network failure or network failure should also be considered an emergency. The device must be intrinsically safe against such hazards or disturbances. However, a failure in the available primary power can also cause an emergency and should not result in the development of any hazard. All these emergencies can also occur in combination.

In this context, the various construction forms and application cases for such thermodynamic cyclic processes must be considered separately, for example, the following in the case of stationary systems for residential buildings:

- domestic refrigerators,

- domestic freezers,

- domestic dryers,

- domestic fridge-freezer combinations,

- cold rooms for hotels and restaurants,

- freezer chambers for hotels and restaurants,

- installation of air conditioning for the home, hotels and restaurants,

- generation of hot water for the home, hotels and restaurants,

- heating for home, hotels and restaurants,

- sauna-swimming pool installations for the home, hotels and restaurants,

- combined systems for the above applications,

this list is not complete.

The energy for the operation of the systems, including the thermal energy that has to be transferred, can come from different sources:

- geothermal energy from geothermal accumulators,

- geothermal heat,

- district heating,

- electrical energy from the general current supply,

- solar electric energy,

- solar heat,

- lost heat,

- hot water tanks,

- ice packs,

- latent heat accumulators,

- fossil energy sources such as natural gas, oil, coal,

- renewable raw materials such as wood, pellets, biogas,

- combinations of the aforementioned energy sources,

This list is not complete either.

The problems that arise in the security design of such systems are clearly described in WO 2015/032905 A1. The lower flammability limit of propane as a working fluid is about 1.7 volume percent in air, which corresponds to 38 g/m3 in air. Whenever the cooling process is carried out with the propane working fluid in a surrounding space that is hermetically sealed, but is otherwise filled with air, the problem arises of detecting a critical and explosive situation after a failure where the working fluid present in this hermetically sealed space escapes. Electrical sensors to detect critical concentrations are difficult to make explosion-proof, so precisely the detection of propane by the sensors themselves greatly increases the risk of explosion, with the exception of infrared sensors. Propane is also toxic, when inhaled above a concentration of about 2 g/m3 narcotic effects, headaches and nausea appear. This concerns people who have to solve a recognized problem on site before there is a risk of explosion.

Propane is also heavier than air, so it sinks to the ground in still air and accumulates there. Therefore, if some of the propane accumulates in a low current area of the enclosed space in which the malfunctioning unit is located, local explosive limits may be reached much faster than would be expected from the total volume ratio. of space and the amount of propane that has escaped. Document WO 2015/032905 A1 tries to solve this problem by integrating an electrical energy generator in the opening, or blocking it, of this space and making it, when activated, in a first stage generate and make available the electrical energy with which the sensor is activated and, in the event of an alarm, does not then release the blockage, but rather gives rise to a ventilation of the closed space and only in a second stage allows an unblocking and an opening.

DE 102011 116863 A1 describes a method for ensuring a device for a thermodynamic cyclic process that is operated with a process fluid containing or consisting of at least one environmentally hazardous, toxic and/or flammable substance. In the event of a leak in the device for a thermodynamic cycling process, an adsorbent is brought into contact with the process fluid, in particular ammonia, propane or propene, and the adsorbent selectively binds the substance. The adsorbent is regenerated after use. Zeolite, also in combination with imidazole or phosphates, and also CuBTC are proposed as adsorbents; the adsorbent can be in the form of a bulk product, a molded body, a paint, a spray film or a coating. The supporting structure of the molded body may consist of a microstructure, a laminar structure, a tube bundle, a tube manhole, and a plate, and must be mechanically stable and considerably increase in surface area. Potentially contaminated air is usually circulated continuously, but such circulation can also be started by a sensor that starts ventilation after a threshold value is reached or if a fault is detected. Adsorption can be carried out inside or outside a closed space.

DE 19525064 C1 describes a refrigerating machine with a gas-tight casing, in which all refrigerant-carrying machine components are housed, a space being provided connecting the interior of the gas-tight casing with a outlet and the space being filled with a substance that adsorbs the refrigerant. In this context, the amount of adsorbent substance is dimensioned in such a way that the entire amount of refrigerant that may eventually escape can be adsorbed and kept away from the environment. The space filled with the adsorbent substance is open to the surroundings. For heavier than air refrigerants the space is open at the bottom, for lighter than air it is open at the top, so a transport fan is not required. The adsorbent is introduced into the casing and completely encloses the refrigerating machine or refrigerant transport equipment. Diverters are provided on their way out, preventing bypass flows and forcing escaping gas through the adsorbent. A double-walled embodiment is also possible, in which the adsorbent is arranged in the double shell. A metering device for refrigerant can be provided at the outlet of the space filled with the adsorbent substance to the environment. EP 2918987 A1 shows a cartridge that can be directly connected to the service valve of the pressure system, without the interposition of a line, a flexible tube or other interconnection arrangement. The adapter, which consists only of a fitting in which the inlet to be coupled to the cartridge is next to the outlet to be coupled to the service valve, prevents the formation of air in the adapter. Therefore, with this arrangement, there is no need to expel the air normally contained in the hose or in the line or other intermediate arrangement.

Therefore, the object of the invention is to provide a device that enables a service intervention if a leak has occurred and there may still be flammable working fluid inside the casing.

The invention achieves this goal by means of a device for a safe service intervention for a casing in which there is a flammable working fluid of a left-hand cyclic process, where

- the casing has a gas passage open to the environment, protected by an adsorbent for the working fluid,

- the casing has a service opening which, by means of an unlocking device, is protected against opening,

- the service opening has a service connection for a service cartridge,

- the service cartridge contains an inert gas under pressure in an amount that, in the expanded state, corresponds at least to the volume of the container,

- the service cartridge has a cartridge neck with a connection line in the cartridge neck and an external thread in the cartridge neck,

- the service connection has an internal thread that coincides with the external thread of the cartridge neck,

- the service connection has a closing cap,

- the closing cover comprising a sealing seal directed towards the outer side of the casing,

- in addition, a sealing membrane directed towards the inside of the housing, on which a pin is arranged towards the outside of the housing,

- in addition, a sealing surface on the internal thread.

The invention also achieves the objective by means of a method for opening a casing in which there is a flammable working fluid of a left-handed cyclic process, where

- the casing has a gas passage open to the environment, protected by an adsorbent for the working fluid,

- the casing has a service opening which, by means of an unlocking device, is protected against opening,

- the service opening has a service connection for a service cartridge,

- the service cartridge contains an inert gas under pressure in an amount that, in the expanded state, corresponds at least to the volume of the container,

- the service cartridge has a cartridge neck with a connection line in the cartridge neck and an external thread in the cartridge neck,

- the service connection has an internal thread that matches the external thread of the cartridge neck, - the service connection has a closing cap,

- the closure cap comprising a sealing seal directed towards the outside of the casing, - in addition, a sealing membrane directed towards the inside of the casing, on which a pin is arranged towards the outside of the casing ,

- additionally a sealing surface on the internal thread,

characterized by the following stages of work

- screw the cartridge neck into the service connection,

- continue turning until the pin of the sealing membrane opens the connection line of the service cartridge,

- continue turning until the cartridge neck opens the sealing membrane,

- empty the service cartridge in the casing,

- continue turning until the cartridge neck activates the release device,

- open the service opening.

The invention is explained in more detail below by means of 5 schematic diagrams. Shown: Figure 1 an overview of a heat pump with service module,

Figure 2 a service module before use,

Figure 3 the service module at the beginning of its use,

Figure 4 the service module during use,

Figure 5 the service module towards the end of its use.

Figure 1 shows the cooling circuit 1 of a heat pump with a compressor 2, a condenser 3, a pressure reduction 4 and an evaporator 5 in a closed housing 6. The housing has a heat source connection 7, a heat source feed tube 8, a heat sink feed tube 9 and a heat sink connection 10. In this example, the refrigeration circuit 1 is operated with the flammable working fluid propane, which is also known by the designation R290.

In the event of a leak, the propane can be led together with the exhaust air 18 through the channel 11, which is open to the environment, and through the activated carbon layer 12, where it is separated, while the inert components of the air They can go out into the environment.

The housing 6 has a service opening 14 which has a service connection 15 for a service cartridge 13. The service opening 14 is secured with a release bolt 16 and sealed with a gasket 17. This prevents the service opening 14 from opening in the event of a leak, as long as there is a flammable mixture inside the casing.

Figure 2 shows a service module before use. The service module is made up of the service cartridge 13, which has a connection line 24 with a valve and a cartridge neck 19 with external thread 25, the service connection 15, which has an internal thread 26, a cap 21 closure, which has a sealing membrane 23, a sealing surface 27 of the cartridge neck, which also covers the first turns of the internal thread 26, a sealing seal 20, which protects the internal thread 26 and can be drilled easily, and a pin 22, which is fixed to the sealing membrane 23. In the service cartridge 13 there is an inert gas under pressure, for example nitrogen. The amount of inert gas stored in the service cartridge 13 corresponds at least to the volume of the casing 6 in the expanded state.

Figure 3 shows the service module at the beginning of its use. Here the sealing seal is pierced with the neck 19 of the service cartridge 13 and the external thread 25 of the cartridge neck 19 is screwed into the internal thread 26 of the service connection 15. The sealing surface 27 makes the intermeshing thread turns gas-tight. When screwed in, the pin 22 pierces the closure of the connection line 24, which allows the inert gas of the service cartridge 13 to escape. However, it still cannot flow into the casing 6.

Figure 4 shows the service module in use. After the service cartridge 13 is rotated further, the sealing membrane 23 is pierced and the inert gas can flow through the connecting line 24 into the housing. In doing so, it dislodges the possibly flammable working fluid/air mixture through the activated carbon layer 12 . Such a process takes about ten seconds.

Figure 5 shows the service module towards the end of its use. By continuing to rotate the empty service cartridge 13, the unlocking bolt is moved out of its locked position and the service opening 14 can now be opened.

It goes without saying that this opening can only be done with great care, as inert gas, eg nitrogen or carbon dioxide, can cause suffocation if inhaled. In this context, care must be taken to ensure good ventilation, including that of the installation space. After the service intervention has been carried out, a new blanking cap 21 must be inserted and the unlocking bolt must be returned to its locking position. Whenever the working fluid has flowed out, the activated carbon layer 12 must also be changed.

Reference symbol list

1 cooling circuit

2 Compressor

3 condenser

4 Pressure reduction

5 Evaporator

6 Casing

7 Heat source connection

8 Heat source feed tube

9 Heat sink feed pipe

10 Heat sink connection

11 Channel

12 Activated carbon layer

13 Service cartridge

14 Service opening

15 Service Connection

16 Release bolt

17 board

18 exhaust air

19 Cartridge Neck

20 Blanking Seal

21 End cap

22 Spike

23 sealing membrane

24 connecting line

25 external thread

26 internal thread

27 Cartridge neck sealing surface

Claims (2)

1. Device for a safe service intervention for a casing in which a flammable working fluid of a counterclockwise cyclic process is located, where - the casing (6) has a gas passage open to the environment, protected by an adsorbent (12) for the working fluid, - the casing (6) has a service opening (14) which, by means of an unlocking device (16), is protected against opening, - the service opening (14) has a service connection (15) for a service cartridge (13), - the service cartridge (13) contains an inert gas under pressure in an amount which, in the expanded state, corresponds at least to the volume of the container (6), - the service cartridge (13) has a cartridge neck (19) with a connection line (24) in the cartridge neck (19) and an external thread (25) in the cartridge neck (19), - the service connection (15) has an internal thread (26) that coincides with the external thread (25) of the neck (19) of the cartridge, - the service connection (15) has a closing cap (21), - the closing cover (21) comprising a sealing seal (20) directed towards the outer side of the casing (6), - in addition, a sealing membrane (23) directed towards the inside of the casing (6), on which a pin (22) is arranged towards the outside of the casing (6), - in addition, a sealing surface (27) on the internal thread (26). 2. Procedure to open a casing in which there is a flammable working fluid of a left-handed cyclic process, where - the casing (6) has a gas passage open to the environment, protected by an adsorbent (12) for the working fluid, - the casing (6) has a service opening (14) which, by means of an unlocking device (16), is protected against opening, - the service opening (14) has a service connection (15) for a service cartridge (13), - the service cartridge (13) contains an inert gas under pressure in an amount which, in the expanded state, corresponds at least to the volume of the container (6), - the service cartridge (13) has a cartridge neck (19) with a connection line in the cartridge neck (19) and an external thread (25) in the cartridge neck (19), - the service connection (15) has an internal thread (26) that coincides with the external thread (25) of the neck (19) of the cartridge, - the service connection (15) has a closing cap (21), - the closing cover (21) comprising a sealing seal (20) directed towards the outer side of the casing (6), - in addition, a sealing membrane (23) directed towards the inside of the casing (6), on which a pin (22) is arranged towards the outside of the casing (6), - in addition, a sealing surface (27) on the internal thread (26), characterized by the following stages of work - screw the cartridge neck (19) into the service connection (15), - continue turning until the pin (22) of the sealing membrane (23) opens the connection line (24) of the service cartridge (13), - continue turning until the cartridge neck (19) opens the sealing membrane (23), empty the service cartridge (13) in the casing, continue turning until the cartridge neck (19) activates the unlocking device (16), open the service opening (14).