FI76003C - FOERSTAERKNINGSFOERFARANDE OCH -ANORDNING FOER GAS. - Google Patents

Description

1 76003

The present invention relates to a concentration method according to the preamble of claim 1 for dividing a gas into subcomponents, in particular for separating oxygen from air.

The invention further relates to an enrichment apparatus according to the preamble of claim 3 for dividing a gas into sub-components, in particular for separating oxygen from air.

Oxygen is known to be used e.g. in incineration, wastewater treatment, fish farming, chemical process industry and various combustion processes and as purified respiratory air e.g. hospitals. The industrial production of oxygen currently takes place mainly in two ways, namely by distillation or by an absorption process.

The most significant manufacturing process is distillation at high pressure and low temperature, whereby the various subcomponents of air (nitrogen, oxygen, argon, etc.) are distilled by condensation to separate liquids at certain pressures. The advantage is therefore that subcomponents other than oxygen can also be separated.

The gases thus prepared are pressed into pressure vessels at high pressure, usually about 20 ... 30 Lipa, for transport to the distribution vessels at the place of use.

Oxygen is also separated from the air in the so-called by selective adsorption based on the screening of gas molecules characteristic of air subcomponents. In this method, the action is based on the ability of a suitable substance to bind different molecules to its pores in different ways by physical adhesion. In this case, the pore size of the substance to be used must be chosen exactly when the aim is to slow down the rate of propagation of the second molecule and, on the other hand, to allow the other molecule (of different size) to travel as smoothly as possible. When natural i 2 76003 or synthetic zeolite is used, oxygen molecules with a small diameter (about 3.8 A) pass through the layer of adsorbent faster than larger nitrogen molecules. Thus, when 4 A is chosen as the theoretical pore size of the zeolite, oxygen is separated, whereby the gas flowing through the layer of matter is oxygen-rich. In this context, reference may be made to the article "Zeolite st r Lie t.ur e, composi t i on and c: at a 1 ysi s" (Dwyer J.,

Chemistry and Industry, 1984 no. 7, pp. 258-269) and in DE-1280225.

The adsorption process is carried out as a standard pressure swing adsorption (PSA) process, in which the adsorbent layer is regenerated after the adsorbent, leading to a flow of regeneration gas opposite to the absorption flow. The resuscitation is usually carried out at a lower pressure corresponding to about atmospheric pressure than the separation, which preferably takes place at a pressure of about 500 to 700 kPa. The structure of the tank used is at least double-tank, whereby when one tank is separated the other tank is revived. Apparatus, pressure, water and oil separation filters, collecting tank for separated oxygen and, if necessary, a muffler. Equipment related to the adsorption process has been presented e.g. in the following publications, US-4194890, US-4263018, US-4373938, GB-2109266 and FI-843014. It is known to use a similar adsorption dryer to remove moisture from i1ma.

The ability of the zeolite to separate the gas components is impaired by the possible presence of moisture. As a result, the use of dryers prior to the actual separation process has been proposed in several publications. In this connection, the following publications can be mentioned, DE-1265144, DE-1259857, EP-123911 and EP-128545.

There are some weaknesses associated with the above gas separation process. The largest of these is the large size of the distillation apparatus, in which case the apparatus itself is considerably expensive. In addition, gas distribution becomes problematic and considerably expensive due to transportation. This is especially pronounced in sparsely populated areas. For transport, the gas still has to be compressed to a high pressure of about 20 MPa, although the operating pressure of the gas is usually in the order of about 500 kPa. Compression requires a lot of energy, which in turn raises the cost of gas production.

So far, quite a few adsorption equipments have been put into production, however, the disadvantages and weaknesses inherent in the distillation process 11e can be substantially eliminated. The equipment can be constructed small, thus making it possible to place it in the vicinity of the object of consumption. In this case, the advantage is e.g. the fact that the gas pressure does not need to be raised above the operating pressure of the gas. Furthermore, operating costs are limited to the cost of acquiring the energy required to produce the compressed air consumed.

One disadvantage of the asorption method with the equipment currently in use is the insufficient achievable oxygen content. In known installations it is typically about 60 7, but not more than 80 7 .. However, such concentrations are completely insufficient, e.g. in incineration, where an oxygen content of more than 90 7 is absolutely required.

Another significant drawback is the complex regulation and control system required by the pressure fluctuation process. In known devices, microprocessor control and electrically or magnetic actuators such as solenoid valves have generally been used. However, these are not suitable for use in humid and cold conditions such as of-f-share or fish farms.

It is an object of the present invention to obviate the disadvantages and disadvantages associated with the known separation methods described above and to provide a new and simpler device for distributing gas to sub-components.

These objects have been achieved by the method and apparatus according to the invention, the characteristic features of which are set out in the appended claims.

The invention is thus based on the basic idea that an apparatus is used to divide the gas into sub-components, comprising in combination at least - a gas supply device, preferably a compressor, for compressing the gas, preferably air, - water separation filters arranged in connection with the gas supply device. is removed, - optionally an adsorption dryer optimized for desiccant, cycle times and other operating parameters to produce dried compressed air, preferably with a dew point of about -40 degrees Celsius, - a gas component separation tank containing an adsorbent layer, preferably to separate oxygen and nitrogen, - a storage tank for the gas component separated from the feed gas, - a piping connecting the various parts of the apparatus in flow communication with each other, and - pneumatically adjusting and controlling means for controlling the gas flows in the various in the parts and in the piping connecting them, in particular for recirculating a part of the gas component in the storage tank back to the adsorption tank for resuscitation of the adsorbent tank, and - for storing

Il S 76003

The advantage of the gas component separation apparatus according to the invention is that the apparatus is reliable even in dew and cold conditions, which is facilitated by pneumatic logic and pneumatic actuators.

In this context, it should be emphasized that in this application, pneumatic means purely compressed air. The driving force is thus only compressed air and the control or regulating means do not include any electrical components. This also applies to logic, ie a control system whose components include mechanical clock devices operated by compressed air as well as memories.

According to the invention, the control system has an integrated structure. Most of its components are arranged on a single circuit board, which in turn is enclosed in a sealed housing, preferably using hybrid circuit board technology, which can achieve a long service life of several million connections. Thanks to this solution, the control system is protected from moisture and cold. In addition, the need for the required pressure hoses is less. Furthermore, it can be stated that the use of pneumatics does not cause a spark hazard and no electricity is required; operation fully pneumatic.

According to a preferred embodiment of the invention, the dryer can be used to dry the feed gas. In this case, the operation of the separation equipment is substantially improved compared to previous solutions, especially in humid conditions. In addition, a large amount of stainless steel is used in the apparatus according to the invention.

It is known to use various adsorbents, such as silica gel or, in particular, synthetic or natural zeolite, for the actual gas separation. Examples of natural zeolites are mordenite and mordenite / clinoptiolite. Of the synthetics are suitable e.g.

Type A and X sodium zeolites such as 5A or 13X. In addition to aluminum or sodium ions, other metal ions, such as calcium and strontium ions, may be present in the molecular structure of the zeolite 6 76003 pathway. The theoretical pore size of the zeolite should be about 4 Å and its water volatility> 200 degrees Celsius.

The most significant advantages of the invention compared to the previous solutions are the following: 1) Compared to the distillation system: - The price of oxygen is cheaper (depending on the degree of purity 1/5 ... 1/10 of the market price).

- Transport of oxygen pellets becomes unnecessary.

- Compression of oxygen to high pressure can be avoided by means of a <two-pressure system in daytime low pressure and at night filling of high pressure cylinders for peak consumption t).

- Many applications do not necessarily require 997 oxygen, so the use of expensive, pure oxygen is not economical.

2) Compared to other adsorption systems: - Higher achievable oxygen concentration or purity (= above i 90 * /. Up to 98 7.).

- Higher yield: 1 nm / oxygen at 1 nm / min pressure pressure, ie about 87. of the theoretical oxygen content at 927 ..

- 2 nm / h of oxygen at 1 nm / min of 1 matoltol 1a, ie about 167. of the theoretical amount of oxygen at a concentration of 877 ..

- The above values are at least double the devices on the market.

Better performance values are based primarily on the use of a dryer prior to the gas component separation unit. However, it only increases the fiber content by about 10 7, which means only a slight increase in operating costs, when it is possible to increase the yield by 50 7 and at the same time substantially increase the purity.

In the tests performed, the pneumatically controlled and controlled separation equipment according to the invention has been found to operate e.g. in a cold sea-i1 mast without any interference.

The invention will now be described, by way of example, with reference to some preferred embodiments thereof, with reference to the accompanying drawings, in which Figure 1 shows in principle a separation apparatus for dividing gas into sub-components schematically shows a separated gas boosting unit belonging to an apparatus according to a preferred embodiment of the invention.

Compressor 1 draws in the intake air from the normal environment and supplies a certain amount of air per unit time (= 100 V.) at a certain pressure (norm. 700 ... 750 kPa). The air is passed to a trace cooler 2, which may be part of the compressor 1.

As the temperature drops, the moisture in the air begins to condense (at the dew point) into water, which is why an automatic condensate drain 3 is connected to the refrigerant to remove the condensate generated periodically or continuously. The air is further led to a pressure vessel 4, the size of which is determined by the size and type of compressor.

Water also condenses in the tanks as the air cools, in which case it is necessary to use 8 76003 1 dehumidifiers 5 to ensure trouble-free operation. Air is passed from the tank 4 through the filters 6 and 7. The first of these is the pre-filter 6 and the second the fine filter 7. The pre-filter b removes most of the dripping water entrained in the air, whereby it is connected to a dehumidifier 8. The fine filter 7 is mainly intended to separate the oil from the air.

If the compressor is oil-free (i.e., produces oil-free air), the fine filter can be omitted from the system, to remove oil the fine filter 7 has a dehumidifier 9. Separating the oil from the air to the dryer is important because the absorbent efficiency is reduced and service life substantially shortened.

Compressed air is supplied to the dryer alternately in either tank 14 or 15 filled with adsorbent (silica gel or molecular sieve) by means of main valves 10 and 11. The valves are controlled by microprocessor-based programmable automatics 1a 27, which is, however, preferably pneumatic logic. If the tank 14 (including the tower) dries, the valve 10 is open and the valve 11 is closed. Similarly, the so-called. the resuscitation valve 12 closed and the resuscitation valve 13 connected to the tank 15 open.

In this case, the air flows from the filter 7 through the valve 10 to the tank 14 and dries as it progresses (water is adsorbed on the desiccant). As it exits the tank 14, air passes through the non-return valve 20 through the filter 24, since the non-return valves 18 and 21 are in the blocking direction. A small portion (usually 10 ... 12 7. heatless type dryers and 2 ... 4 7. heat regenerative dryers) is used to revitalize the second dryer 15 (now a tank tower). This amount is controlled by the choke 23 and is taken from the main flow through the filter 22.

The resuscitation air passes from the throttle 23 through the check valve 19, because the throttle drops the pressure. The pressure behind the check valve 18 is about 700 kPa. The resuscitation air continues to flow into the tank 15 because the counter valve i 1 in 21 is depressed at the rear because, on the other hand, at the lower end of the tank, the valve 15 is open and the valve 11 is closed. Thus, the resuscitation air flushes the tower 15 in the opposite direction to the air flow in the tower 14 and is released after binding moisture through the valve 13 and the muffler 16 to the outside air.

Thus, the drying tank 14 has a pressure generated by the compressor 1 (e.g. 700 kPa) and the regenerated tank 15 a lower pressure (e.g. normal pressure).

After a predetermined time, preferably 9 minutes, when the drying of the tank 14 has started, the valve 13 closes, which prevents the passage of the resuscitation air out of the tank 15, whereby the tank 15 begins to pressurize.

When both tanks 14 and 15 are at the same pressure, the positions of the valves 10 and 11 are changed, i. valve 10 is closed and valve 11 is opened. In this case, the air coming from the compressor 1 begins to pass through the tank 15. After a certain time (e.g. 10 seconds), the valve 12 is opened, at which point the pressure in the tank 14 drops and its resumption can begin. In this way, the drying is made continuous during the operation of the tanks 14 and 15 alternately.

The dried compressed air is discharged from the outlet by a filter 1 e 24, the function of which is to remove the dust released into the air from the desiccant. The pressure is then reduced by a pressure reducer to a suitable value, which is preferably about 500 kPa. The air vents are equalized by tank 26.

Instead of or to supplement the operation of the drying unit 14,15, a layer of moisture adsorbent can be placed in the gas component separation tank 34 following the drying unit. Preferably, the full layer of material is fitted to the bottom portion of the container.

In the embodiment according to Fig. 1, after the drying of the air in the drying unit 14,15, the air is led to a gas tank separation tank 34, hereinafter referred to as an oxygen separator. The end of the oxygen separator inlet (and resuscitation outlet) side is constructed similar to that of the drying tank 14 or 15. The valve 28 is a main valve 5 which directs the passage of air to the adsorption tank 34 and the valve 30 controls the flow of nitrogen-rich exhaust gas from the tank 34.

It is assumed that the tank 34 is adsorbed. In this case, the valve 28 is open and the valves 30 are closed, whereby the air passes into the tank 34, through which the flow of oxygen takes place faster than the flow of nitrogen. From the outlet when the valve 36 is open, oxygen enters the filter 42 through the non-return valve 38, after which the flow rate is controlled by the choke 43 and further through the backup valve 41 the storage tank 45 in which the separated oxygen is stored. After the choke, it is advantageous to place a flow meter (not shown in the figure).

When the adsorption tank 34 starts to produce oxygen, i.e. when the valve 28 is open, the valve 26 is also open from the start of the output for a certain time, typically 7 seconds, allowing oxygen to flow through the backup valve 41 to the storage tank 45 and begin to pressurize with pure oxygen. After about 7 seconds of continuous pressurization, during which the pressure in the storage tank 45 has risen to about 500 kF, the oxygen production is stopped by closing the valve 36.

Thereafter, typically after about 11 seconds, resuscitation of the adsorption tank 34 is initiated by opening the valve 30, whereupon the adsorption tank 34 begins to empty out through the muffler 32, allowing the nitrogen-rich air accumulated in the adsorption tank 34 to escape. After a period of time (typically about 16 seconds), the adsorption tank 34 is emptied of overpressure. In addition, valve 37 is opened to allow oxygen to flow from storage tank 45 to backup valve 39, filter 42, choke 43 and backup valve 40 to adsorb typically about 7 seconds, with valve 30 open and reservoir 34 resuscitated, then valves 30 and 37 are closed and valve 28 is opened and dried air begins to flow into one of the adsorption tanks 34. it begins to pressurize, which typically takes about 11 seconds. , after which the operation of the adsorbent tank 34 continues as described above.

Oxygen is introduced from the storage tank 45 by opening the shut-off valve 46 and selecting direct operation or high-pressure charging via valve 51. In direct operation (0 ...

500 kPa) of oxygen is supplied to the pneumatically controlled pump 49 and from there to the distribution piping 50. In high pressure charging, the pressure of the oxygen gas from the storage tank is raised from the pneumatically controlled booster unit 70 to the desired pressure, e.g. for filling the oxygen cylinder shown in Fig. 1.

As a pressure boosting unit 70, a system such as Fig. 4 can be used, for example, with which the final gas pressure can be raised from a pressure of 500 kPa in the storage tank 45 to up to 70 MPas. Components suitable for such a system are commercially available from Schmidt, Kranz & Co. GMBH and are referred to below using the product codes of the company indicated in brackets. The booster unit shown includes; in the lower pressure range, 200 kPa ... 32 MPa, operating first, two-stage working cylinder 71 (OLE 5-30); a second, two-stage working cylinder 72 (DLE 75-10; a pressure accumulator intermediate tank 74 operating in a higher pressure range, 3.5 MPa to 70 MPA, arranged between said series-acting working cylinders 71 and 72; working cylinders 71; And 72 is operated by a control steering unit 75, the supply air pressure of which is typically between 100 kPa ... 1.1 MPa; a first, shut-off valve acting on the first working cylinder 71, the second shut-off valve 77 and a pressure control valve 78 acting on the second working cylinder 72.

The operation diagram of the pressure vessel supply valve 28, the nitrogen removal valve 30 and the oxygen removal valves 36 and 37 is shown in Fig. 2. The times mentioned in the diagram are infinitely adjustable.

Pneumatic timers and directional valves have been used to control valves 28, 30, 36 and 37. The control also includes a safety valve that stops the cycle if the pressure in the adsorption tank exceeds a predetermined value. The control system is integrated, most of the pneumatic components are fitted to the circuit board, so that all the flow channels between them are in said board and no separate pressure hoses are required. The pneumatic components mentioned below are commercially available from 0V FEST0 AB and are referenced using the product codes of the said company.

As shown in Fig. 3, the compressed air supply valve 28 and the nitrogen removal valve 30 are connected in turn to operate. Instead, the oxygen removal valves 36 and 37 are connected in parallel. Said valves are VLX-2 type pneumatic diaphragm valves. The operation of the valves is controlled by a so-called -f 1 ip — f 1 op ventt ii 1 i 52 acting as a changeover switch, which is connected to a pulse valve 53 with a single output, which remembers the operating cycle. VLL-5-PK-3- (52) and components of the J-3-3.3- (53) type, respectively. The actual timer of the control system consists of four VUZ-type timing units 55, 56, 57 and 58. They have pneumatic mechanical clock devices in which the desired time sequence is set. They control as shown in the wiring diagram, ie both via the memory valve 53 and directly (valve

II

76003 13 lit 36 .ia 37) kai voventt i i 1 i en activities. The J-5-3.3 pulse valve 59 with two outputs directly controls the operation of the two timing units (56 and 58) and the changeover switch 52.

To ensure the operation of the adsorption tank, a pressure sensor is installed in it, which is connected to a pressure control valve 62 of the VD-3-3.3 type. The upper pressure limit is set to 800 kPa. The pressure control valve 62 is connected in parallel with the manually controlled control valve 63 (SV-3-M5-N-22-S) to the main shut-off valve 61 (VL / 0-3-3.3). This in turn is connected to the "or" valve 60 (OS-6 / 3-3.3), to which a second control valve 64 is also connected.

The control system is actuated from the control valves 63 (or 64), after which the system operates automatically, adjusting the operation of the valves 28, 30, 36 and 37 according to the set sequence (shown in Figure 2). If the pressure of the adsorption unit rises too high, the main shut-off valve 61 stops the cycle. However, it can be restarted from the control valve 64 (or after the pressure has been reduced from the control valve 63).

The control system operates fully pneumatically using a pressure of 500 ... 600 kPa. Compressed air is supplied via a device from a pressure source known per se, such as a compressor. The pressure source is not shown in the drawings. Compressed air is supplied to the system as shown in Figure 3 through the control valves 63 and 64.

f

The pneumatic components 52 ... 62 are housed in a single circuit board housed in a sealed housing. The control valves are mounted on the outside of the housing. Due to such an arrangement, only the compressed air hoses between the control valves and the circuit board and the circuit board and the well valves, respectively, are required.

76003 14

A control system assembled from similar pneumatic components 52 to 64 can advantageously be used to also control the operation of the main valves 10 and 11, the discharge valves 12 and 13 of the two-tank drying unit.

The invention has been described above only by means of a preferred embodiment thereof. This, of course, is not intended to limit the invention, but various variations of the invention and / or its details are possible within the scope of the appended claims.

Thus, the adsorbent dryer may also consist of a single tank, in which case a separated gas component recyclable from the separation tank is used to regenerate it. It should further be noted that the compressor 1 required to compress the air acting as the supply gas can be replaced by the compressed air already available. While the structure of the system remains the same, by changing the operating cycles, can the oxygen separation tank 1 i ö be adapted to different ones? operating values. The assembly consisting of the separation tank and the storage tanks or reservoir can be doubled, whereby the feed gas of the latter configuration is a high oxygen gas separated in the first configuration, and thus it is possible to achieve a high degree of purity. '

II

Claims (13)

Concentration process for dividing a gas into sub-components, in particular for separating oxygen from air, characterized in that the process comprises - in successive steps - pressurizing the air to a pressure higher than normal pressure, - removing the condensing water during the pressurization, obtained in a tank (34) containing an adsorbent suitable for separating the gas components, such as natural or synthetic zeolite, from the product stream to the intermediate storage is recycled through the adsorbent tank (34) to remove the nitrogen-rich gas bound to the adsorbent, and that the flow of pressurized air to the adsorbent tank (34) and the oxygen-rich product stream the flow of sun and nitrogen-rich exhaust gas from the adsorption tank (34) is controlled and regulated by means of pneumatic actuators (28,30,36,37,52 ... 64), whereby the separation of oxygen from the air takes place reliably and safely even in humid and / or cold conditions . Method according to Claim 1, characterized in that the pressurized air from which the condensed water has been separated is passed to at least a two-tank drying unit (14, 15) with a moisture-adsorbing agent, preferably silica gel or a molecular sieve, to dry the air to a suitable humidity. so that, after excavation, the dew point of the compressed air is about -40 degrees Celsius, and that the flow of compressed air to the moisture adsorbing unit (14), the dried air flow 76003 1 (15) is controlled and adjusted by means of pneumatic actuators (10 ... 13,18 ... 21). Gas concentration apparatus, in particular for separating oxygen from air, characterized in that it comprises in combination at least: - a gas supply device (1), preferably a compressor. With which the gas, preferably air, is condensed, - water separation filters (3,5,6) arranged in connection with the gas supply device (1), and with which the water separated from the gas during compaction is fried, - optionally an adsorption dryer (14,15) optimized with respect to desiccant, cycle times and other operating parameters, to produce dried compressed air, preferably with a dew point of about -40 degrees Celsius, a storage tank (45) for the separated gas component, - piping connecting the various parts of the equipment to each other in flow communication, and - pneumatically adjusting and controlling means (28,30, 36,37,52 ... 64) for controlling the gas flows in the various parts of the equipment and in the piping connecting them, in particular the part in the storage tank (45). for recirculating the gas from the sub-component back to the adsorption tank (34) for revitalizing the adsorption tank, and - means arranged after the storage tank (45) for rigidly treating the separated gas component, preferably a pneumatic booster unit (70) Apparatus according to Claim 3, characterized in that the control elements consist of pneumatic valves (28, 30, 36, 37) and pneumatic components (32 to 64) which control and operate their operation. Apparatus according to claims 3 and 4, characterized in that the drying unit comprises at least two adsorbent units (14, 15) which preferably contain silica gel or a molecular sieve as a moisture adsorbent, and that the adsorbent unit comprises an incoming air flow and pneumatic means (10 ... 13) for regulating the air flows leaving it, preferably valves. Apparatus according to claim 4 or 5, characterized by a moisture adsorbing desiccant layer arranged in the adsorption tank (34, 35). » Apparatus according to any one of claims 4 to 6, characterized in that said control valves consist of pneumatic valves (10 ... 13; 28, 30. Apparatus according to one of the preceding claims 3 to 7, characterized in that the pneumatic components controlling the operation of the pneumatic control elements (10 to 13, 28, 30, 36, 37) comprise at least pneumatic timers (55 to 58 ) and pneumatic impulse valves (53,59). Apparatus according to one of Claims 3 to 8, characterized by a pressure control valve (62) connected on the one hand to pressure sensors located in the adsorption tank (34) and on the other hand to the main shut-off valve (61) of the pneumatic control system (52 to 64). adapted to stop the cycle of the apparatus if the pressure in the adsorption tank exceeds a predetermined, maximum permissible value. Apparatus according to one of Claims 3 to 9, characterized by a pressure control valve (62) which is connected, on the one hand, to 76003 pressure sensors located in the drying tanks (14, 15) and on the other hand to the main shut-off valve (52 to 64) of the pneumatic control system. 61), and which is adapted to stop the cycle of the equipment if the pressure of vaueäi 1 i örv exceeds a predetermined, maximum permissible value. Apparatus according to any one of claims 3 to 10, characterized in that the control system is integrated in a common housing, wherein most of its components (52 to 64) are housed in said housing, which is to be sealed. Apparatus according to one of Claims 3 to 11, characterized by a pneumatically controlled product gas boosting unit (70) arranged downstream of the storage object (45) in the direction of the product gas flow. Apparatus according to claim 12, characterized in that the booster unit (70) comprises; - a first, two-stage working cylinder (71) operating in a lower pressure range, - a second, two-stage working cylinder (72) operating in a higher pressure range, - an intermediate tank (74) provided with a safety valve (73) arranged 71,72), - a control unit (75), - a first shut-off valve (76) acting on the first working cylinder (71), - a second shut-off valve (77) and a pressure control valve (78) acting on the second working cylinder (72). Il 76003 19