FI76002C - Gas amplification method and apparatus - Google Patents

Description

1 76002

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 the gas into subcomponents, 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 at certain pressures into liquids. 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 MPa, for transport to sites of use in distribution tanks.

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 2 76002 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 connection, reference may be made to the article "Zeolite structure, composition and Catalysis" (Dwyer J., Chemistry and Industry, 1984 No. 7, pp. 258-269) and to DE-1280225.

The adsorption process is usually carried out as a "pressure swing adsorption" (PSA) process, in which the adsorbent layer is regenerated after the adsorption step by introducing a flow of regeneration gas opposite to the adsorption flow. The resuscitation is usually performed 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 equipment used is at least double-tank, so that when one tank is separated, the other tank is revived. The equipment also includes a compressed air supply, usually a compressor, water and oil separation filters, a collection tank for separated oxygen and possibly 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 the air.

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The ability of the zeolite to separate the gas components is impaired by the possible presence of moisture. As a result, several publications have suggested the use of dryers prior to the actual separation process. In this connection, the following publications may 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 distillation

The large size of the 3 76002 machine makes the equipment itself 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 producing gas.

So far, relatively few adsorption equipment have been introduced into production, however, the adsorption equipment can substantially eliminate the disadvantages and weaknesses inherent in the distillation process 11e. 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 adsorption method with the equipment currently in use is the insufficient achievable oxygen content. In known installations it is typically about 60 '/., However, not more than 80 Ti. However, such concentrations are completely inadequate, e.g. in incineration, where a concentration of more than 90 V is absolutely required.

Another major drawback is the complex regulation and control system required by the pressure fluctuation process. Known devices generally use microprocessor control and electrically or magnetically operated actuators such as sonicoid valves. However, these are not suitable for use in humid and cold conditions such as e.g.

o-f-f-shdre or fish farms.

It is an object of the present invention to obviate the disadvantages and weaknesses associated with the known separation methods described above and to provide a novel apparatus for dividing gas into sub-components.

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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 placed in connection with the gas supply device. , - 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, - thereafter, at least a double-tank gas component separation unit, each adsorbent tank containing to separate the fluidized bed, preferably oxygen and nitrogen, - 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 parts of the apparatus and the other. in the piping connecting them.

The advantage of the gas component separation apparatus according to the invention is that the apparatus is reliable even in humid 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 therefore only compressed air and not I! 5 76002 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.

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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 compressed air 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 for the actual gas separation, such as silica gel or, in particular, synthetic or 1-zoololite. Examples of natural Zeol Ute include mordenite and mordenite / clinoptilolite. Of the synthetics, e.g. type A and X sodium zeolites, such as 5A or 13X, are suitable. 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 zealite · The theoretical pore size of the zeolite should be about 4 A and its water volatility> 200 degrees Celsius.

The most significant advantages of the invention compared to the previous solutions are as follows: 6 76002 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).

- The transport of oxygen powders becomes unnecessary.

- Compression of oxygen to high pressure can be avoided (with a two-pressure system, low pressure during day operation and high pressure cylinder filling at night for peak consumption).

- 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 (= over 90 7. up to 98 7).

- Higher yield: 1 nm / oxygen with 1 nm / min of compressed air production, ie about 87. of the theoretical amount of oxygen at 927 ..

- 2 nm / h oxygen at 1 nm / min compressed air production, ie about 167 theoretical amounts 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. If only an increase of about 10 is required, which means only a small increase in operating costs, when it is possible to increase the yield by 50 V 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-i 1 mast without any disturbance.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a schematic diagram of a separation device according to the invention for dividing gas into sub-components, Fig. 2 shows a logic drawing of pneumatically operated valves, and Figure 3 shows a circuit diagram of the pneumatic components.

Compressor 1 draws in the intake air from the normal environment and supplies a certain amount of air per unit time (= 100 7.) at a certain pressure (norm. 700 ... 750 kPa). The air is led to an aftercooler 2, which may be part of the compressor 1.

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Moisture in the air begins to condense (at dew point) into water as the temperature drops, 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, so that it is necessary to use a condensate drain 5 to ensure trouble-free operation. The air is passed from the tank 4 through the filters 6 and 7. The first of these is a pre-filter 6 and the second a fine filter 7. The pre-filter 6 removes most of the dripping water entrained in the air, in which case a condensate drain Θ is connected to it. The fine filter 7 is mainly intended to separate the oil from the air, which is generated if the compressor 1 is oil-lubricated.

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 condensate drain 9. Separating the oil from the air supplied to the dryer is important because the adsorbent efficiency decreases and service life substantially shortens.

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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.

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The valves are controlled by a microprocessor-based programmable automation 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.

The air then flows through the filters 7 through the valve 10 into 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 to the filter 24, since the non-return valves IS and 21 are in the blocking direction. A small part (usually 10 ... 12 V. in heatless type dryers and 2 ... 4 7. heat-revived 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 non-return valve 19 because the throttle drops the pressure and there is a pressure of about 700 kPa behind the non-return valve 18. The resuscitation air continues to flow into the tank 15 because there is pressure behind the non-return valve 21 and 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 revitalized tank 15 a lower pressure (e.g. normal pressure).

For a predetermined time, preferably 9 minutes, after the drying of the tank 14, the valve 13 closes, which prevents li; ‘76002 the flow of resuscitation air out of the tank 15, whereby the tank 15 begins to become pressurized.

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 or 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 decreases and its resuscitation can begin. In this way, the drying is made continuous with the operation of the tanks 14 and 15 taking place alternately.

The dried compressed air is led from the outlet to a filter 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 25 i to a suitable value, which is preferably about 500 kPa. The air flow is 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 each of the tanks 34 and 35 of the gas component separation unit following the drying unit. Preferably, such a layer of material is fitted to the bottom of the container.

After drying the air in the imaging unit, the air is passed to a gas component separation unit, hereinafter referred to as an oxygen separator. The inlet (and resuscitation outlet) end of the oxygen separator is constructed similar to that in the dryer. Valves 28 and 29 are main valves that direct air flow to tanks 34 and 35. Valves 30 and 31, respectively, control the flow of nitrogen-rich exhaust gas from tanks 34 and 35.

It is assumed that the tank 34 is in the adsorption shift. In this case, the valves 28 and 31 are open and the valves 29 and 30 are closed, whereby air passes to the tank 34, through which the flow of oxygen 10 76002 proceeds faster than the flow of nitrogen. From the outlet when the valve 36 is open, oxygen enters the filter 42 via a non-return valve 38, after which the flow restrictor v 43 adjusts the flow rate, which is measured by a flow meter 44. The separated oxygen is stored in the tank 45.

When the unit produces oxygen, i.e. when the valve · 36 is open, the valve 31 is also open for a certain time, typically about 8 seconds, from the beginning of the output, allowing oxygen to flow after the valve 36 through the backup valve 41 to the tank 35 and. from there on out to the muffler 33 of the valve 31, thus removing and purging the tank 35 of nitrogen-rich air.

After the time has elapsed, the valve 31 closes, at which point the blow-out from the tank 35 ceases and its pressurization with pure oxygen begins. The duration of pressurization is typically about 7 seconds, after which oxygen production is stopped by closing valve 36 and at the same time changing the operation of the tanks by opening valve 29 and closing valve 28. At this time, tank 35 begins to pressurize as air flows through valve 29 into the tank.

Thereafter, typically after about 11 seconds, the valve 30 is opened, at which point the reservoir 34 begins to drain out through the muffler 32, thereby removing nitrogen-rich air. After a period of time, typically about 16 seconds, the pressure in the tank 35 has reached its maximum value <n. 500 kPa) and at the same time the tank 34 has been emptied of overpressure.

In this case, valve 37 is opened, at which point oxygen production begins. The output takes about 8 seconds with valve 30 open and reservoir 34 resuscitating. The valve 30 is then closed, after which the operation of the tank 34 continues as already described.

Oxygen is introduced from the surge tank 45 by opening the shut-off valve 46 and selecting low pressure operation or high pressure charge 76002 charging via three-way valve 51. In low pressure operation (0-500 kPa) oxygen is supplied to storage tank 48 from where it can be further distributed to applications. In high-pressure operation, the pneumatically controlled high-pressure pump 49 fills the 20 MF'a high-pressure vessels connected to the distribution piping 50 and stops automatically when said pressure is reached.

The operation diagram of the compressed air supply valves 28 and 29, the nitrogen removal valves 30 and 31 and the oxygen removal valves 36 and 37 is shown in Fig. 2. The times mentioned in the diagram can be adjusted steplessly.

Pneumatic timers and directional valves have been used to control valves 28,29,30,31,36 and 37. The control also includes a safety valve that stops the cycle if the pressure in the absorption tank exceeds a predetermined value. The control system is integrated, most of the pneumatic components are fitted in a 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 OY FEST0 AB and are referred to using the product codes of the said company.

As shown in Fig. 3, the compressed air supply valves 28 and 29 and the nitrogen removal valves 30 and 31 are connected to operate in turn. Instead, the oxygen removal valves 36 and 37 are connected to operate in parallel. Said valves are VLX-2 type pneumatic manhole valves. The operation of the valves is controlled by a so-called -f 1 ip ~ f valve 52 acting as a changeover switch, which is connected to impulse valves 53 and 53 with a single outlet, which remember the operating cycle. In the example, VLL-5-PK-3- (52) and J, respectively, are used. -3-3.3- <53 and 54) types' components. 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, i2 76002 is set the desired time sequence. They control the operation of the well valves v as shown in the wiring diagram, i.e. both via the memory valves 53 and 54 and directly (valves 36 and 37). The J-5-3.3 impulse valve 59 with two outlets directly controls the operation of the two timing units (56 and 58) and the changeover switch 52.

To ensure the operation of the adsorption tanks, they are fitted with pressure sensors connected to a VD-3-3.3 type pressure control valve i 1 i in 62. The upper pressure limit is set to 800. kPa. The pressure control valve 1 and 62 are connected in parallel with the manual 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 an "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 valve 63 (or 64), after which the system operates automatically, adjusting the operation of valves 28, 29, 30, 31, 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 from the pressure control valve 63).

The control system operates using a pressure of 500 ... 600 kP and fully pneumatically. Compressed air is serviced through the device from a compressed air source known per se, such as a compressor. The compressed air 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.

The pneumatic components 52 ... 62 are housed in a single circuit board housed in a sealed housing. hTallinta valves are mounted on the outside of the housing. Thanks to such an arrangement, only compressed air hoses between the control valves and the circuit board and between the circuit board and the well valves li 76002 13, respectively, are required.

A control system which can be assembled from similar pneumatic components 52 to 64 can advantageously also be used to 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 pneumatic control system described above can be applied in a slightly simplified manner to control the main valves 10 and 11 of the dryer. In this case, it can be guaranteed that the dryer will work smoothly * even in humid and cold conditions.

The structure of other parts of the equipment may differ from the above. 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 hardware unit remains the same, the separation unit can be adapted to different operating values by changing the operating cycles. In addition, two oxygen separation tanks can be used in succession, the other being smaller. In this case, a two-stage separation can be achieved, with which the degree of purity can be raised by flowing a relatively large amount of gas through a larger tank.

This system is preferably used when a particularly high degree of purity is required.

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Claims (11)

76002 A concentration method for dividing a gas into sub-components, in particular for separating oxygen from air, characterized in that in successive steps: - the air is pressurized to a coarser pressure than normal air pressure, - the condensing water is removed during pressurization, and the pressurized air is optionally The adsorbent in the adsorption step of the unit (34, 35) is maintained overnight. (34), which contains an adsorbent suitable for separating the gas components, such as natural or synthetic rheolite, (35) to remove the nitrogen-rich gas bound to the adsorbent, and that the flow of pressurized air to the adsorption unit (34,35) and the flow of oxygen-rich product gas and nitrogen-rich exhaust gas from the adsorption unit (34,35) are controlled and regulated by pneumatic actuators (28). ... 31,36,37,52 ... 64), in which case 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 desiccant, preferably silica gel or a molecular sieve, to dry the air to a suitable humidity. after drying, the dew point of the compressed air is about -40 degrees Celsius, "and that the compressed air flow to the moisture-adsorbing drying unit (14), the dried air-flow-absorbing drying tank (14) and the moisture-binding dried air-flow-recovering dryer ) 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 the apparatus comprises in combination: - an air supply device (1), preferably a compressor, for pressurizing the supply air, - water separation means (3,5,6) arranged preferably in the supply device (1) - optionally a moisture adsorbing drying unit (14,15) for drying the pressurized air, which drying unit is located downstream of the water separating means - a gas adsorption unit (34,35) consisting of at least two adsorbent reservoirs with gas separation units a suitable adsorbent, such as natural or synthetic zeolite, - optionally an intermediate gaseous product stream from the adsorption unit, a tank (45), as well as any spacing between the tank (45) the pneumatic regulating and controlling means (28 ... 31,36,37, 52 ... 64). Apparatus according to Claim 3, characterized in that the control elements consist of pneumatic valves (28 ... 31, 36.37). and pneumatic components for controlling and regulating their operation (52 ... 64). 16 76002 Apparatus according to claims 3 and 4, characterized in that the drying unit comprises at least two adsorbent containers (14, 15) containing preferably silica gel or a molecular sieve as a moisture adsorbent, and that the adsorbent unit comprises pneumatic control means (10 ... 13) for the air flow and 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 diaphragm valves (10 ... 13, 28 ... 31). 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 ... 13, 28 ... 31, 36.37) comprise at least pneumatic timers (55 .. .58) and pneumatic impulse valves (53,54,59). Apparatus according to one of Claims 3 to 8, characterized by a pressure control valve (62) which is connected on the one hand to pressure sensors located in the adsorption tanks (34, 35) and on the other hand to the main shut-off valve (61) of the pneumatic control system (52 to 64). 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 integral. here "connected to pressure sensors located in the drying tanks (14,15) and on the other hand to the main shut-off valve (61) of the pneumatic control system (52 ... 64), which is adapted to stop the pressure of the apparatus during its cycle (I; 17 76002 exceeds a predetermined maximum allowable value. Apparatus according to 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. · · 76002 18