RU2395721C2 - Compressor unit comprising compressor element with water injection - Google Patents

Abstract

FIELD: engines and pumps. ^ SUBSTANCE: compressor unit comprises water-injection compressor element. Inlet line 4 and outlet line 5 and inlet air filter 13 are connected to said compressor element. Said inlet line 4 and water separator 6 are connected to said compressor element. Inlet line 5 feeds air into said water separator. Return line is arranged between said water separator 6 and compressor element 2. Inlet air filter 13 represents housing 14 with air inlet 15, air outlet 16 whereto connected is inlet line 4. It comprises also substrate 17 to be fitted into said housing 14 for sucked air to flow through. Inlet air filter 13 represents a wet filter with water feed device connected thereto. Substrate 17 consists of open cellular structure material. Water feed device consists of at least line 20 connected to water separator 6 and extra water feed device. ^ EFFECT: reduced production costs, higher efficiency of filter and compressor. ^ 22 cl, 4 dwg

Description

The present invention relates to a compressor unit comprising a water injection compressor element.

In particular, the present invention relates to a compressor installation comprising a water injection compressor element to which an inlet line and an outlet line are connected, an air inlet filter to which the inlet line is connected, a water separator into which the said outlet line is supplied with air, and a return line between said water separator and compressor element.

In compressor elements with water injection, the rotating parts and, in particular, the screws in the screw compressor elements are lubricated with water, not oil. This water also serves as a seal between these rotating parts, and it provides cooling, while actually providing isothermal compression.

Humidity of gas and, in particular, air depends on its temperature and pressure. Inside the compressor element, gas is mixed with water, and the gas saturation level at the outlet of the compressor element is always 100%.

Depending on the absolute humidity of the gas at the inlet and its pressure at the outlet of the compressor element, the compressor element with water injection thus either consumes or produces water. The higher the absolute humidity of the gas at the inlet and the higher the pressure at the outlet, the lower the amount of water consumed. On the other hand, the compressor element will consume more water if the absolute humidity at the inlet drops and / or the pressure at the outlet is less.

For this reason, known compressor installations comprising a water injection compressor element also have a water supply device to add water if necessary.

Typically, the water to be added is injected through a return line directly between the rotating elements or at the inlet of the compressor element.

However, this water must meet certain stringent requirements.

The water consumed is chemically pure water, so if ordinary water is added, water consumption will increase the concentration of salts and other similar substances in the remaining water. This can lead to damage to the compressor element and, in particular, to seals and bearings.

Adding water or consuming pure water can also change the pH value of the water in the circuit, which in turn can lead to corrosion.

It is known that for this reason water is added through reverse osmosis, which is why the water supply device has a relatively high cost.

According to WO-A-96/21109, the water that was separated in the water separator after the compressor element is returned to this compressor element through an ionizer, in which natural minerals dissolved in water, such as silicon, calcium, magnesia and iron, are converted to the hydroxide form after which they acquire an electric charge.

Since hydroxide particles have the same polarity, their accumulation and, therefore, deposition are prevented. However, since these parts retain their charge only temporarily, the ionization process must be repeated continuously, and the circulating water must be pumped through the ionizer several times per minute. Moreover, precipitation is not completely excluded, and the injected water should also be filtered to prevent other contaminants from entering.

The aim of the present invention is to resolve one or more of the above and certain other disadvantages.

Thus, the present invention relates to a compressor installation comprising a water injection compressor element to which an inlet line and an outlet line are connected, an inlet air filter to which the inlet line is connected, a water separator into which the said outlet line is supplied with air, and a return line between this water separator and a compressor element, wherein said air inlet filter is a housing comprising an air inlet opening, an air exhaust opening to which and said inlet line is connected, a substrate which is inserted into this housing and through which intake air passes, said inlet air filter being a wet filter to which a water supply device is connected, said substrate consisting of a material with an open cellular structure, said device the water supply contains at least one of: a line that is connected to said water separator, and a supply device for additional water.

By injecting water into the air inlet filter, the air is simultaneously humidified and cleaned, since contaminants are captured by the injected water droplets and removed. Part of the injected water evaporates and is transferred in the air stream to the compressor element.

Since the part of the water that was injected into the inlet air filter enters the compressor element together with the suction gas in the form of water vapor, this water is chemically pure water and has no effect on the level of minerals and salts, nor on the pH of the water for injection.

A compressor installation of this type has the advantage that the intake air of the compressor element is humidified to such a level that during periods when the surrounding air is dry, additional supply of demineralized water or water that has been purified by reverse osmosis is no longer required.

Another advantage of the compressor unit according to the present invention is that its manufacturing cost is relatively low, and that it exhibits significantly higher filtration efficiency than conventional air filters without water injection.

An additional advantage is that the inlet air filter of the compressor unit according to the present invention causes a lower pressure drop than conventional dry air filters, which increases the performance of the compressor.

Another additional advantage of the compressor installation according to the present invention is that it provides the ability to add water in a relatively simple and inexpensive way, without compromising the quality of the water present in the circuit and without any risk of damage to the compressor element due to increased settling of minerals or similar substances .

An additional advantage is that in variable speed compressors between the air inlet filter and the inlet to the compressor element, there is no longer a need for an inlet valve or “unloading valve” to absorb water hammer when the compressor stops, because water hammer can pass through the inlet line, which passes between the inlet air filter and the compressor element, and, as appropriate, into the drain line extending from this wet inlet air filter a.

Since said air inlet filter is a housing into which a substrate is inserted through which intake air passes, and this substrate is an open cell structure material such as polyurethane foam, polyethylene or similar material, the contact surface between the water and the intake air increases, from which it follows that the air is optimally humidified and purified.

A preferred feature of the compressor installation according to the present invention is that said inlet air filter is provided with an element for stopping water droplets in the gas stream in order to prevent water droplets from entering the intake air inside.

In a preferred embodiment of the compressor unit according to the present invention, said water supply device is formed from a line connected to said water separator.

This gives the advantage that the water released from the water separator can be used by injection into said air inlet filter, thereby making it possible to restrict the supply of additional water.

Another advantage is that the inlet air filter in such a compressor unit operates on the principle of self-cleaning due to the fact that it is periodically sprayed with clean water released from the water separator.

In a further preferred feature of the present invention, said water supply device to the air inlet filter is an additional water supply device.

This embodiment has the same advantages as the embodiment in which the added water is recovered from the water separator, and furthermore, provides the possibility of supplying additional water to the compressor unit.

For a clearer presentation of the distinguishing features of the present invention, below, by way of example and without limitation, a preferred embodiment of a compressor unit according to the present invention is described with reference to the accompanying drawings, in which:

figure 1 is a schematic illustration of a compressor unit according to the present invention;

figure 2 and 3 are illustrations of the operation of the compressor unit of figure 1;

figure 4 is a control curve that is followed during the operation of the compressor installation of figure 1 in normal mode with a sufficient amount of water vapor in the intake air; and

5 is a control curve that is followed during the operation of the compressor installation of figure 1 in the mode with a very small amount of water vapor in the intake air, for example, during extreme winter weather.

Figure 1 illustrates a compressor unit 1 according to the present invention, which is equipped with a compressor element 2, for example, in the form of a screw compressor element, which is driven by a motor 3 and to which an input line 4 is connected. An output line 5 is connected to the output of the compressor element 2, which feeds into the water separator 6.

A return line 7 connects the lower part of the water separator 6 to the compressor element 2. In this return line 7, a cooling device 8 is installed, which in this example, although not necessary, is cooled by a fan 9, which is driven by the engine 10.

However, said cooling device 8 may also take many other forms, such as a liquid-liquid heat exchanger.

On the upper part of the water separator 6, a minimum pressure valve 11 for compressed air is installed, which opens at a predetermined opening pressure in the water separator and to which a compressed air line 12 is connected to supply compressed air to the main network.

An inlet air filter 13 is inserted into said inlet line 4, which in this case consists of a housing 14 with an air inlet 15 and an air outlet 16 to which said inlet line 4 is connected. A substrate 17 is inserted into said housing 14 through which intake air passes.

Said inlet air filter 13 should preferably also be provided with an element 18 or a “droplet eliminator” to prevent water droplets from entering the gas stream, as well as a drain line 19 for contaminated water.

Said substrate 17 and element 18 should preferably be a material with an open cellular structure, such as polyurethane foam, polyethylene or a similar material. Obviously, the present invention is not limited to the use of any one of these materials for the manufacture of the substrate 17 and the element 18, and many other materials can also be used.

In a preferred embodiment of the compressor unit 1 according to the present invention, the substrate 17 and / or element 18 consists of a material into which one or more bacteriostatic substances, such as nano-silver, are added. However, it should be noted that this is not mandatory according to the present invention.

In the present invention, said substrate 17 is located at the bottom of the housing 14, while the element 18 is inserted into the upper part of the housing 14. Said air inlet 15 is located at the bottom of the housing 14, opposite the substrate 17, while the air outlet 16 is located at the upper part the housing 14 of the inlet air filter 13, opposite the element 18.

Said inlet air filter 13 according to the present invention is a wet filter to which a water supply device is connected, which in this case is a line 0, one end of which is connected to said water separator 6 and its other end is connected to said air filter 13 through a sprinkler 21, which injects water into said inlet air filter 13, and more particularly between the substrate 17 and the element 18.

A controllable valve 22 is introduced into said line 20 between the water separator 6 and the inlet air filter 13.

The compressor unit 1 is also provided with an additional water supply device 23, which in this case also forms part of said water supply device to the air inlet filter 13 and which in this example is connected to said air inlet filter 13 through a sprinkler 24.

Said supply device 23 essentially consists of a supply line 25, for example for tap water, into which a control valve 26 and a water filter 27 are inserted.

Said water filter 27 preferably consists of an absolute filter with a throughput of 5 μm, whose β value is 1000, that is, its efficiency is 99.9%. However, if desired, a nominal water filter can also be used according to the present invention, although the efficiency of the latter is usually lower than the efficiency of an absolute water filter.

As is known, the value of β mentioned above is the ratio between the number of particles of a given size that are present in the water stream before filtration and the number of particles of the same size that are present in the water stream after filtration.

In this example, although this is not necessary, the aforementioned additional water supply device 23 is further provided with a water-improving agent that prevents the accumulation of calcium salts in the sprinkler 24. The water-improving agent consists of two powerful permanent magnets 29 and 30, which are installed at an angle of 90 ° , and their south poles are directed to the nozzle of the sprinkler 24.

At least said sprinkler 24 is preferably made of iron-free metal (such as brass or CuNi), so that the water in the nozzle is always in a magnetic field and calcium salts in the sprinkler 24 never accumulate. Preferably, one or both of the sprinklers 21 and / or 24 are in the form of a “flat-jet sprinkler”, which has not a circular hole, but a slit-like one to prevent the formation of deposits.

Preferably, both of said sprinklers 21 and 24 spray water inside the housing 14 of the air intake filter 13 and, more specifically, between the substrate 17 and the element 18, and they are also made of iron-free corrosion-resistant metal. It is also preferred that both of these sprinklers 21 and 24 have an internal filter to prevent clogging of a very thin nozzle.

In a preferred embodiment, said sprinklers 21 and 24 consume 0.9 liters of water per hour at a pressure of 7 bar (7000 Pa). However, it is obvious that sprinklers 21 and 24 are not limited in this regard, and many other types of sprinklers can be used.

The compressor unit 1 according to the present invention is also equipped with a level control, which is not shown in the drawings. Said level controller is connected to a minimum and maximum level sensor, respectively, at levels A and B in the water separator 6, as well as to said controlled valves 22 and 26.

The operation process of the compressor unit according to the present invention is very simple and is illustrated in FIGS. 2 and 3.

When the compressor element 2 is driven by the engine 3, the air is sucked in through the air intake filter 13 and the inlet line 4. Then it is compressed by the compressor element 2 and passed through the output line 5 to the water separator 6 and then passed through the minimum pressure valve 11 to the compressed line 12 air.

Water which is released from the compressed air by means of said water separator 6 is transferred via a return line 7 through a cooling device 8 and then injected into the compressor element 2 to provide lubrication and cooling of the rotating parts of the compressor element 2.

In the position shown in FIG. 2, the water level in the water separator 6 is at a predetermined maximum level A. This is detected by the said maximum level sensor and is signaled to the level regulator, which in response opens the valve 22, which leads to increased pressure in the water separator 21, water is forced through line 20 to sprinkler 21 and injected into the intake air filter 13.

Water droplets, which are sprayed down, moisten the cellular substrate 17 and fall through this substrate 17 into the drain line 19, as a result of which the substrate 17 becomes completely wet. Water droplets that are sprayed upward are stopped by the element 18, which also has a cellular structure, as a result of which only the lower part of the said element 18 is moistened and water drops are prevented from entering the inlet line 4.

The intake air that enters the air intake filter 13 through the air inlet 15 moves against the falling drops in the substrate 17, as a result of which the air is cleaned and moistened with water drops.

The vast majority of these droplets, together with the dust particles that were accumulated in the substrate 17, are removed through the drain line 19, while a small part of them evaporates and enters the air stream.

Filtered and humidified air passes through the element 18 to the air outlet 16 for the inlet air filter 13 and is then sucked up by the inlet 4 by the compressor element 2, where it is compressed together with the injected water, and the mixture of compressed air and water is transmitted through the outlet of the compressor element 2 to water separator 6.

By means of said minimum pressure valve 11 on said water separator 6, compressed gas is supplied to a compressed air line 12, possibly through a freeze dryer or centrifugal water separator, which are not shown in the drawings and to which a compressed air outlet of said water separator 6 is connected.

If such a freeze dryer or centrifugal water separator is used, then, if necessary, a return line can be arranged, for example, to the inlet of the compressor element 2.

If the amount of water vapor exiting through the compressed air line 12 together with the compressed air is greater than the amount of water vapor entering the inlet filter through the inlet line 4, which implies that water is being consumed, then the water level in the water separator 6 will drop.

For example, this takes place in winter weather, when the absolute humidity of the surrounding air is less than or equal to 2 g / kg.

In this case, as shown in FIG. 3, as soon as the predetermined minimum water level B is reached in the water separator 6, the additional water supply device 23 is activated by opening the valve 26 with a level regulator, while the valve 22 in the line 20 between the water separator 6 and the air intake filter 13 closes.

The additional water supplied through the supply line 25 first passes through the water filter 27, as a result of which any contaminants that may be present in the additional water can be filtered.

However, minerals such as calcium ions may also be contained in the feed water. Such ions can pass through the water filter 27 and settle in the sprinkler 24, which will lead to its blockage.

To solve this problem, for example, a water-improving agent can be used that ensures that calcium salts do not settle, and which is preferably of the type mentioned above, in which a magnetic field is generated that acts on calcium ions so that they lose their adhesion for a certain period As a result, the sprinkler 24 is protected against calcium deposition.

The additional water is then injected through the sprinkler 24 into the air intake filter 13, where the substrate 17 is moistened in the same way as the above scheme, and the air is cleaned and moistened with water droplets.

Contaminants and minerals remaining in the injected water cannot evaporate, and adhere to the substrate 17 and the lower part of the element 18. Some of the particles of pollution are dissolved by water droplets and removed through the drain line 19.

Element 18 stops the droplets in the same way as described above so that the air leaving the inlet line 4 does not include water droplets, and it contains only air and water vapor.

As shown in FIG. 4, by supplying additional water through the valve 26, the water level L in the water separator will increase until the maximum water level A is reached, after which the valve 26 in the supply device 23 closes again and the valve 22 opens again.

In a situation where the amount of water vapor present in the intake air is greater than in the outgoing compressed air, when controlling the valves 22 and 26, the increase in the level L in the water separator 6 is faster than its drop, as schematically shown by the upper curve in figure 4.

When additional water is supplied through the supply device 23 through the supply line 25, there is no continuous loss of water from the water separator 6. As a result, the water level L in the water separator will rise.

As a result of additional humidification of the intake air through the air intake filter 13, the maximum water level A will be quickly reached. Since the time during which additional water is transferred to the intake air filter 13 is limited, water consumption, for example, from the main network will also be limited.

When the maximum water level A in the water separator is reached, the valve 26 on the supply device 23 will be closed and the valve 22 on the line 20 will be open.

As shown by the central curve D in FIG. 4, in this case, the period during which the valve 22 remains open will be significantly longer than the period during which it is closed, and vice versa, as shown by the lower curve E in FIG. 4, the period during which valve 26 remains open, shorter than the period during which it is closed. The open and closed positions of the valves 22 and 26 are indicated by the symbols O and C, respectively.

In contrast, if the absolute humidity of the intake air is less than the absolute humidity of the exhaust air, which usually occurs in extreme winter conditions, the water consumption through the supply device 23 will be greater.

As a result, as shown by the central curve F in FIG. 5, the period during which the valve 22 is opened will be shorter, because in addition to the continuous leakage of water from the water separator 6 to the sprinkler 21, due to the low absolute humidity of the intake air, the continuous consumption of water provides quickly achieving a minimum water level B in the water separator 6, as illustrated by the upper curve in FIG.

In contrast, as shown in the lower curve G in FIG. 5, the period during which the valve 26 is open is longer since the continuous consumption of water from the water separator 6 must be compensated for due to the extremely low absolute humidity of the intake air. During these periods, the consumption of additional water will be higher than during non-winter periods.

This will take place mainly in countries where extremely low temperatures are observed in winter. The closer the region to the equator, the less likely this situation will occur, since the absolute humidity increases as you approach the equator.

The compressor unit 1 according to the present invention is not limited to the embodiment shown in the drawings, in which water is supplied to the air inlet filter 13 both through line 20 and through the device 23. According to the present invention, it is also possible that water is supplied to the air inlet filter 13 is carried out only through one of these mechanisms.

According to the present invention, the possibility of using an additional level sensor that is installed in the water separator 6 at a level below the minimum water level B and which is connected to a control mechanism that controls the said engine 3 is thus possible. Thus, in cases where there is extremely high water consumption and water supply are insufficient to compensate for this consumption, or in case of failure of the minimum level sensor, the compressor element 2 can be turned off.

In all embodiments, the problems associated with the deposition of minerals and salts in the screw compressor element 1 are prevented in a simple and inexpensive manner, and higher volumetric productivity is achieved. The water quality in the circuit remains constant and thus is not affected by the additional supply of water when water is consumed.

The quality of the additional water supplied is not important, since only water vapor, i.e. chemically pure water, enters the compressor element 1. This can be of great importance when the compressor unit is located in places where clean water is not available.

According to one feature of the present invention, the compressor unit is not provided with an inlet valve or an “unloading valve” to absorb water hammer that occurs when the compressor stops.

The present invention is in no way limited to the embodiments described and shown in the drawings in the following sense: a similar compressor installation comprising a water-injected compressor element can be produced in many different ways within the scope of the present invention.

Claims (22)

1. A compressor installation comprising a compressor element with water injection, to which an inlet line (4) and an outlet line (5) are connected, an inlet air filter (13) to which the inlet line (4), a water separator (6) are connected, in which supplies air to said outlet line (5) and a return line (7) between this water separator (6) and compressor element (2), said air inlet filter (13) being a housing (14) containing an opening (15) for air inlet, hole (16) for exhausting air to which said input line (4), a substrate (17), which is inserted into this housing (14) and through which intake air passes, characterized in that said intake air filter (13) is a wet filter to which a water supply device is connected ; moreover, the aforementioned substrate (17) consists of a material with an open cellular structure; and said water supply device comprises at least one of: a line (20) that is connected to said water separator (6), and an additional water supply device. 2. The compressor installation according to claim 1, characterized in that the said substrate (17) is made of polyurethane foam, polyethylene or similar material. 3. Compressor installation according to claim 1, characterized in that said substrate (17) consists of a material into which one or more bacteriostatic substances are added. 4. Compressor installation according to claim 3, characterized in that said substrate (17) consists of a material into which nano-silver is added. 5. Compressor installation according to claim 1, characterized in that said inlet air filter (13) is provided with an element (18) for collecting water droplets in a gas stream in order to prevent water droplets from getting inside with intake air. 6. Compressor installation according to claim 5, characterized in that said element (18) consists of a material with an open cellular structure. 7. Compressor unit according to claim 5, characterized in that said element (18) consists of polyurethane foam, polyethylene or similar material. 8. Compressor installation according to claim 5, characterized in that said element (18) consists of a material into which one or more bacteriostatic substances are added. 9. Compressor installation according to claim 8, characterized in that said element (18) consists of a material into which nano-silver is added. 10. A compressor installation according to one or more of the preceding claims, characterized in that said air inlet filter (13) is provided with a drain line (19) for contaminated water. 11. The compressor installation according to claim 1, characterized in that said water supply device is a line (20) that is connected to said water separator (6). 12. Compressor installation according to claim 11, characterized in that a controllable valve (22) is introduced into the said line (20) between the water separator (6) and the inlet air filter (13). 13. The compressor installation according to claim 1, characterized in that said water supply device is a supply device (23) for additional water. 14. Compressor installation according to claim 13, characterized in that said additional water supply device (23) is provided with a controllable valve (26) and a water filter (27). 15. A compressor installation according to claim 14, characterized in that said water filter (27) of the additional water supply device (23) consists of an absolute water filter. 16. Compressor installation according to claim 14 or 15, characterized in that said additional water supply device (23) is additionally provided with water-improving means, which prevents the precipitation of calcium salts. 17. The compressor installation according to clause 16, characterized in that the said water-improving means is equipped with two permanent magnets (29 and 30). 18. Compressor installation according to claim 17, characterized in that the said permanent magnets (29 and 30) are installed at an angle of 90 °, and their south poles are directed to the sprinkler nozzle (24), to which the aforementioned supply device (23) is attached water to said inlet air filter (13). 19. Compressor installation according to claim 18, characterized in that said sprinkler (24) is made of iron-free metal. 20. Compressor installation according to claim 18 or 19, characterized in that said sprinkler (24) is a flat-jet sprinkler with a slit-like opening. 21. The compressor installation according to item 12 or 14, characterized in that it is equipped with a level controller, which is connected to the minimum and maximum level sensor in the water separator (6), as well as to the said controlled valves (22 and 26). 22. The compressor installation according to claim 1, characterized in that it is not equipped with an inlet valve for absorbing water hammer when the compressor stops (2).

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