JPH0347884B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a device for removing oxidizing, especially gaseous, contaminant components from a gaseous stream, especially air. During manufacturing processes in many industries such as printing operations, dye and paint factories, food and food material processing factories, chemical factories and many small workshops, oxidizing suspended solids and gases are generated and are malodorous. May be flammable and/or toxic. These substances are carried by air currents and for economic reasons are often discharged directly into the atmosphere without prior cleaning. Increasingly stricter regulations from authorities and, however, increasingly higher demands from the public have made such airflow purification necessary even in cases where it was not previously necessary. . Purification of such air streams is expensive and technically difficult. That is about 1.5 of the material to be removed.
per hour, usually containing small amounts of less than g/Nm ³
This is because large quantities of 100000Nm ³ or more are often targeted. Known methods for purifying air streams can be broadly divided into four categories: cleaning, adsorption, thermal oxidation, and catalytic oxidation. Cleaning is typically performed with water, often by adding chemicals that react with undesirable substances in the air stream. Disadvantages of this method, besides being expensive, are that the practical problem of rendering undesirable substances harmless is only partially solved because they are simply transferred to the water. It's not too much. Adsorption is mostly carried out on activated carbon. The major problem with this process is that the regeneration of the activated carbon necessary to make the process sufficiently economical cannot be achieved at all. The reason for this is that regeneration must be carried out in an oxygen-free atmosphere, which is typically a superheated flow atmosphere. Many of the materials to be removed from the carbon tend to form polymerization products that clog the pores of the carbon particles.
Partial removal of these polymerization products may be accomplished by maintaining the temperature in the range of 700-800°C in an oxygen-free atmosphere, but such high temperatures cause decomposition of the activated carbon.
Other adsorbents such as molecular sieves and refractory ceramic oxides such as alumina, Al ₂ O ₃ may also be used. However, molecular sieves are significantly more expensive than activated carbon, and refractory ceramic oxides have lower adsorption capacity than activated carbon. The advantage of these non-flammable adsorbents is that they can be regenerated with air. Thermal oxidation is distinguished by being a simple and relatively reliable method. The disadvantage of this method is that the heating of a large volume of air to 700-800° C. in the combustion chamber requires a large amount of energy. Usually the air is superheated by an open flame with oil or perhaps gas. Even if some of the heat present in the bulk air can be utilized, this method is still expensive to implement. Catalytic oxidation differs from thermal oxidation in that oxidation occurs in the catalyst bed rather than in the combustion chamber. The advantage of this process is that the catalytic oxidation can take place at temperatures between 250 and 350 DEG C., whereby the energy consumption is substantially reduced. A drawback of catalytic oxidation is that some catalysts are poisoned by contact with substances such as hydrogen sulfide H ₂ S and sulfur dioxide SO ₂ . It is particularly important that even though the energy consumption of catalytic oxidation is substantially less than that of thermal oxidation, it is still considerable when large volumes of air are superheated. Due to the small amount of the impurities described, the oxidation of the impurities is not sufficient to provide enough energy to superheat the air. It is an object of the present invention to eliminate or reduce the disadvantages associated with known processes and to achieve effective purification with substantially less energy consumption compared to known thermal oxidation and catalytic oxidation processes. The purpose of this invention is to provide a gas and air purification method for pollutants. This involves (a) passing the gas to be purified at temperatures between 0 and 250°C through a bed of particulate adsorbents which have a large specific internal surface area and are impregnated with substances active as oxidation catalysts at elevated temperatures ( b) oxidatively oxidizing the adsorbent (catalyst) by increasing the temperature to a temperature in the range of 250-350°C to initiate catalytic oxidation of the pollutants accumulated on and in the adsorbent (catalyst); This is achieved by regenerating intermittently. It is a great advantage of the method that it is possible to take contaminated air at its actual temperature and treat it without preheating. The main part of the amount of air to be purified in this way is absorbed by adsorbents (hereinafter abbreviated as adsorbents) which act as oxidation catalysts at elevated temperatures, either at the temperature at which they were formed or perhaps at a slightly lower temperature due to heat losses. No energy is used to pass through the body (called the catalyst) and thus overheat it. If desired, the heat of the gas before adsorption can be utilized by passing it through a heat exchanger. During the passage, the pollutants or most of them are adsorbed onto the adsorbent (catalyst) and the air can be released into the environment in an essentially purified state. Adsorbent (catalyst)
As it becomes increasingly saturated with impurities, its leakage into the environment will occur. and the temperature passage required for catalytic oxidation when the concentration of undesirable substances reaches the permitted or permissible maximum value 250 ~
Regenerate the adsorbent (catalyst) by increasing the temperature to a range of 350 °C. At this temperature the oxidation of the contaminants on the adsorbent (catalyst) begins; during this time the temperature may rise further. Heat supply is therefore only required during the period when regeneration is to take place. Under certain circumstances, apart from starting up the plant for carrying out the process, it is possible to carry out completely without heat supply or even to obtain heat, as explained later in the specification. According to the invention as an adsorbent (catalyst) a large specific internal surface area (70 to 250 m ² /g, preferably 100 to
200 m ² /g) and impregnated with a substance that acts as an oxidation catalyst at elevated temperatures is used. porous ceramic itself,
It may act as an adsorbent, but it may not act as an oxidation catalyst, or it may act only a little. A series of ceramic materials in the form of oxides, in particular of the elements of the periodic table and groups, are particularly suitable. An example of a suitable material is aluminum oxide, Al ₂ O ₃
(hereinafter referred to as alumina), magnesium aluminum spinel, MgAl ₂ O ₄ , and silicon dioxide (hereinafter referred to as silica). Gamma-alumina is a particularly suitable material, but oxides of Ti and Zr and similar ceramic oxides may also be used. The carrier can consist of a mixture of two or more of the materials. A support as described is conveniently impregnated with a catalytically oxidizing active substance at elevated temperatures. Such substances include the metals of the groups of the periodic table (Handbook of Chemistry and Physics, 53th
ed., 1972-3) and their compounds, especially oxides, can be used, especially platinum. Other suitable substances are copper and the b, b and b groups and their oxides, particular emphasis must be given to the oxides of copper, chromium, manganese, iron, vanadium and cerium. The described catalyst has excellent catalytic activity and tolerates regeneration well. Surprisingly, copper chromite, CuO.Cr ₂ O ₃ , was found to combine high adsorption power for the currently problematic oxidizing air pollutants with high activity as an oxidation catalyst. It was. According to the invention, therefore, an adsorbent (catalyst) consisting of γ-alumina impregnated with copper chromite is particularly advantageously used. A particular advantage of this adsorbent (catalyst) is its ability to adsorb large amounts of polymerizable compounds, such as styrene. Many contaminant compounds, such as styrene, will undergo partial polymerization after adsorption onto the adsorbent (catalyst). And copper chromite has the ability to accelerate this polymerization. Such polymerization would contribute to increasing the adsorption capacity and thereby extend the period during which adsorption can occur without regeneration. When the adsorbent (catalyst), in its adsorbent properties, becomes saturated with impurities (this is easily confirmed by the purification becoming ineffective), catalytic oxidation of the adsorbed impurities occurs. Therefore, the temperature is increased. The situation where some of the adsorbed material is probably polymerized will not make regeneration difficult. In the regeneration, the temperature can be increased in any suitable manner, preferably to 250-350°C, as described above. That is, it is possible to recirculate the hot gas from the regeneration stage or to apply heat directly to the adsorbent (catalyst) bed, for example using electric heating elements, generally in the direction of flow of the contaminated air. It would be most expedient to insert a combustion chamber, for example heated with oil or gas, upstream of the air leaving the adsorbent (catalyst) bed during regeneration, which is generally In contrast to the air leaving it, it will contain undesirable components. According to the invention, it is therefore advantageous to subject this air to post-purification. Post-purification can be carried out according to any one of the main methods mentioned above, depending on the undesired substances leaving the bed during regeneration: washing, adsorption, thermal or catalytic oxidation. If these substances are oxidizing, it is most advantageous according to the invention for postpurification to occur by catalytic oxidation. As a result, another catalyst can be used in addition to the one used as adsorbent (catalyst), but the same as the adsorbent (catalyst) used in adsorption, from the point of view to keep the equipment and operation as simple as possible. It is most practical to use substances as catalysts. The advantage of carrying out post-purification with catalytic oxidation is in particular that it does not, under certain circumstances, consume energy supplied from outside the operation, apart from the energy present in the air to be purified, but on the contrary The object of the invention is to be able to carry out the above method in a device which even produces usable heat. The invention relates to a device for implementing the method described. According to the invention it comprises at least one reactor with a bed of adsorbent active as an oxidation catalyst at elevated temperature, a feed pipe for supplying the gas to be treated, in particular the air to be purified, to said reactor. , an exhaust pipe for conducting purified gas (air) from the reactor, and means for intermittent regeneration of the adsorbent (catalyst) in the reactor. Optionally, the apparatus can have means for post-purification of the gas (air) emanating from the reactor during regeneration. The means for periodic regeneration of the adsorbent (catalyst) is preferably a combustion chamber with a connected burner inserted into the feed pipe. According to the invention, means for post-purification of the gases emanating from the reactor during the regeneration of the adsorbent (catalyst) are inserted into one branch of the discharge pipe and connected to a second reactor with an oxidation catalyst, a burner. This is the second combustion chamber. The post-purified air emanating from the post-purification reactor can be recycled to the exhaust pipe or conveyed alone to the chimney. Under certain circumstances, part of it can be conveyed to a reactor with an adsorbent (catalyst). This is particularly advantageous when the process uses an apparatus consisting of several reactors equipped with adsorbents (catalysts) and one of them is always in a regeneration state while the other adsorbs impurities. . Such embodiments are particularly advantageous when the concentration of organic material is greater than or equal to about 0.5 g/m ³ of hot gas. This is because it makes it possible to utilize the calorific value exhibited by the oxidizing substance for heating purposes, so that the entire device would, for example, become self-heating or even exothermic. This situation is explained in the detailed description herein and such an apparatus according to the invention is conveniently comprised of at least two first reactors each comprising a bed of adsorbent (catalyst) as defined. (plurality) are connected in parallel to a supply pipe of the gas to be purified); a pipe from the supply pipe to the post-purification section;
parallel discharge pipes from each of the first reactors; parallel pipes from each of the first reactors to the post-purification section; a combustion chamber connected to a burner; a second reaction comprising an oxidation catalyst bed from the combustion chamber; a post-cleaning section comprising a pipe to the reactor and a discharge pipe from the second reactor; a first branch pipe for discharging gases, a second branch pipe being a recirculation pipe to the pipe from the combustion chamber to the second reactor; from a second reaction reactor with two branch pipes and a third branch pipe to the first reactor. The device according to the invention will be more fully illustrated below with reference to the drawings and examples. Of the figures, FIG. 1 is a flow diagram of an apparatus for carrying out the invention, FIG. 2 shows an experimental apparatus in which certain experiments were carried out to illustrate the method described above, and FIG. FIG. 4 is a curve illustrating the results of the experiment. The flow diagram of the device according to the invention is shown in the first
In the figure, there are also a number of detailed parts, such as various blowers, pumps, valves and overall controls, which are not directly relevant to the invention and whose use and function will be clear to those skilled in the art. Since it is obvious, it has been omitted and simplified. Contaminated air enters the device through tube 10;
Tube 10 separates into tubes 42 and 44. A small portion of the air is conveyed via pipe 42 to the post-cleaning section. The bulk portion is conveyed from the pipe 44 through branch pipes 46, 46, . . . to several reactors with adsorbents (catalysts) 18. The device in the figure is 48〓, 48〓, 48〓,
It has six reactors designated 48〓, 48〓, and 48〓. The number of reactors determines the length of the regeneration period compared to the length of the adsorption period in the reactor. The number of reactors 48, . . . will depend, for example, on the amount of air to be treated and its degree of contamination. Purified air is conveyed from the reactor via pipes 50, 50, . . . , all of which are connected to a common pipe 22 which leads the purified air to the chimney.
During actual operation, five reactors are always in the adsorption stage and one is being regenerated. The air for regeneration is supplied to the reactor 4 from a pipe 52 with branch pipes 54, 54, . . . for the individual reactors.
8. Transported to... Another series of pipes 56〓,
56 . . . conducts air from the reactor into a common pipe 58 which conducts the air to the post-purification section. The air emanating from the reactor in which the adsorbent (catalyst) 18 is being regenerated flows from a tube 58 into a combustion chamber 60 which is inserted into the tube 58 and is connected to a burner 62; They function only at the beginning of the development and when the devices are in full operation, the air passes directly through them without being heated. From the combustion chamber 60 , which during normal operation is therefore only part of the tube 58 , air flows further through the remainder of the tube 58 to the connection point 64 . There, the desired amount of hot recirculated air is added through tube 66. In this manner, an inlet stream at the desired temperature is created in tube 68 to reactor 76 containing the oxidation catalyst. The purified air stream is directed from reactor 76 via tube 70 to junction 72 . The recycle flow is previously directed through tube 66 and a portion passes through tube 74. Reactor 7
The purified air flow from 6 is at a considerable temperature (400
~500℃). And for this reason tube 7
The portion leaving via 4 will normally be utilized for heating purposes. At junction 72 the hot, purified air is mixed with contaminated air from line 42 and passed via line 52 to reactor 4 for use in regeneration.
8 〓 forms an air flow that is sent to one of the... An essential advantage of the apparatus of FIG. 1 is that burner 62 is used only during start-up of the apparatus. During normal factory operation, there is therefore no energy consumption in the burner or anywhere else in the apparatus. Conversely, the heat in the air stream 72 would typically be utilized as hot air for a drying oven or for warming, so that the calorific value of the material in the contaminated air can be utilized in the apparatus. It is. Recirculation pipe 66 has a further special meaning. Otherwise, the temperature in the reactor (where the catalyst is an oxidation catalyst and is preferably the same as that used as adsorbent (catalyst) 18) fluctuates strongly and in a complex manner. This will be explained further later in this specification. By suitably adjusting the amount of recirculated air in tube 66 and the amount of air to the regenerated reactor, e.g. 48, the temperature in reactor 76 can be kept relatively constant; There are benefits in connection with the utilization of the air in the tube 74 for heating purposes, and in part important for catalysts; some catalysts and especially support materials may be When raised to high levels, it may sinter or otherwise reduce its activity. However, this can be effectively prevented by adjusting the amount of recirculation. Conversely, the aftercleaning in the reactor 76 becomes insufficient if the temperature becomes too low, in which case it is likewise possible to adjust the recirculation amount. Examples of calculations to explain the operation of the apparatus illustrated in FIG. 1 are provided in Example 1 below. The small-scale pilot plant where several experiments on contaminated air were conducted is shown schematically in Figure 2. Atmospheric air is conducted into the plant through pipe 90. Air flow is measured by flow meter 78 and controlled by valve 80. From the flow meter, the air flows through pipe 8
2 to a cylindrical preheater 84. There, an electric heating coil is provided.
By controlling the effect obtained with the heating coil, the temperature in the tube 10 passing the heated air leaving the preheater can be adjusted to the desired level. tube 88
directs the liquid for contamination to pump 92 which directs the liquid via line 94 into line 10 where evaporation occurs. Tube 10 leads the now contaminated air to reactor 16. A heating coil 96 is provided at the top of the reactor, which allows adjustment of the temperature of the contaminated gas. In the lower part of the reactor an adsorbent (catalyst) 18 is placed as a cylindrical bed 18 with a height of more than 450 mm and a diameter of 73 mm (corresponding to the internal diameter of the reactor). A tube 98 for temperature measurement extends from the bottom of the floor to the top of the floor on the axis of the floor. Inside the temperature measuring tube there is a movable temperature element, by means of which the temperature at various depths of the catalyst bed can be read. The outlet stream from the catalyst bed is led out of the reactor by pipe 20. Pipe 22 and control valve 100 allow a portion of the flow to be directed into a continuously operated hydrocarbon analyzer 102 for analysis. The hydrocarbon analyzer used was Beckmann Model 400.
It is a type of flame ionization analyzer called Hydrocarbon Analyzer. Example 1 This is an example calculation using the apparatus shown in FIG. An air flow of 25000 Nm ³ /h originating from the drying oven of an offset printing factory was conducted into the device. Contaminated air contains 1.5g of hydrocarbons per ^1Nm3 at 130°C.
It has a temperature of The hydrocarbons used as solvents for the printing inks consist of 20% aromatic hydrocarbons and 80% aliphatic hydrocarbons and have a boiling point range of about 240 to about 270°C. The total amount of contaminated dry air is transferred to tube 1.
0 and is guided to the device. A portion of the flow voNm ³ /h is conducted via line 42 for use in regeneration. The remaining (25000-vo) Nm ³ /h is led via pipe 44 to the pipe of reactor 48 in the adsorption stage.
(25000−vo)/5Nm ³ /h in each of the five reactors
distributed to. Each reactor 48 contains 1500 Kg of adsorbent (catalyst). Similarly, the post-purification reaction chamber 76 is
Contains 1500Kg of the same adsorbent (catalyst). Adsorbent 20%
Consists of γ-alumina soaked with CuO.Cr ₂ O ₃ . The length of the adsorption period is limited by two considerations.
First, it must not be so long that the hydrocarbon concentration in the air stream leaving the adsorption is greater than an acceptable value. Secondly, no more than about 15 g of hydrocarbons should be adsorbed per kg of adsorbent (catalyst). This value will ensure that the maximum temperature in the adsorbent (catalyst) does not exceed 800-850°C. When the adsorption period is fixed at 175 minutes, the adsorbent (catalyst)
12.8 g of hydrocarbons per kg are adsorbed, which ensures that during regeneration the maximum temperature in the adsorbent (catalyst) does not exceed the desired value, ie a value that will never destroy the catalyst. During adsorption, the hydrocarbon concentration in the purified gas led to the stack is approximately 2 for the first 100 minutes.
mg/ ^Nm3 . And at the end of adsorption it increases to 5 mg/Nm ³ . Since the number of reactors is 6, the regeneration period will be 35 (175/5) minutes. V ₁ indicates the amount of air conducted to regeneration through tube 52 , V ₂ indicates the amount of air passed through reactor 76 and recycled to tube 66 , and T ₁ indicates the amount of air conducted through tube 52 to reactor 48 .
2 and T ₂ indicates the temperature in tube 5 from reactor 48.
8 and T ₃ indicates the temperature in tube 68 to reactor 76.
Table 1 below shows how the regeneration of the adsorbent in the reactor 48 proceeds when indicating the temperature therein. During regeneration and the first 12 minutes, 1000 Nm ³ /h (V ₀ ) of contaminated air from pipe 42 is mixed with 2000 Nm ³ /h (V ₁ -V ₀ ) of purified hot air from pipe 70 at confluence 72. As a result, the temperature in the tube 54 in question is approximately 318
℃ is obtained. At the temperature obtained, the adsorbed hydrocarbons in the inlet layer in the reactor 48 in question will be ignited and combusted due to the catalytic properties of the adsorbent (catalyst). Hydrocarbons from the contaminated gas used for regeneration will be oxidized along with a portion of the adsorbed hydrocarbons. The remainder of the adsorbed hydrocarbons is desorbed due to the temperature increase and is conducted with the air stream to reactor 76 where oxidation occurs. Within 5-10 minutes after the start of regeneration, the hydrocarbon concentration in the air stream increased to a maximum of 2-3 g/Nm ³ . first 15-20
When the concentration of hydrocarbons in the air in tube 58 is large, the temperature will be relatively low. To ensure sufficient oxidation in reactor 76, the air stream must be heated to at least 260°C, which is achieved by recycling hot air to the reactor via tube 66. . The temperature of the air stream from reactor 76 will maintain a constant value of about 418° C. despite temperature fluctuations in tube 58. This is due in part to the fact that the catalyst in reactor 76 has some capacity as a heat buffer, and in part to the fact that hot air is recycled through tube 66. Therefore, the temperature in tube 74 will also remain nearly constant at 418°C. The amount of purified air in tube 74 will be equal to V ₀ . Twelve minutes after the start of regeneration, the hot air from tube 70 to confluence 72 is stopped, and at the same time tube 42
The amount of contaminated air inside is increased. The rest of the playback
It is carried out with a quantity of 4000 Nm ³ /h of thermally contaminated air at 130°C. Recirculation to reactor 76 is carried out by reactor 4 in question.
Since the air temperature at the outlet starts to rise from 8,
It can be reduced to 3500Nm ³ /h. This temperature will reach a maximum of about 600° C. about 25 minutes after the start of regeneration.
At the same time, the temperature of the purified air stream from reactor 76 will also reach a maximum of about 600°C. The hydrocarbon concentration in tube 58 will drop below 20 mg/Nm ³ in 15-20 minutes after regeneration. The burner 62 does not work during regeneration, but is used only at the start of the device, and therefore there is no energy consumption for heating the air stream during normal operation of the device, which is a major advantage of this configuration. . There is a large amount of heat in the hot, purified air stream carried out through tube 74, as already mentioned.
By cooling the air stream to 130°C, a heat equivalent to the heating value of 27 kg of oil is utilized.

【table】

EXAMPLE 2 In an initial experiment with the implementation shown in FIG. 2, air contaminated with styrene was used.
The adsorbent (catalyst) is spherical with a diameter of 3 to 6 mm and is a gamma-alumina adsorbent with copper chromite as described above. 4.4 Nm ³ /hb of air containing 0.22 g/Nm ³ of styrene and having a temperature of 50° C. is introduced into the catalyst bed. The amount of adsorbent (catalyst) is 1.67Kg
Equivalent to 1.8. The styrene concentration in the outlet stream from the reactor was determined in a hydrocarbon analyzer as ppm in methane equivalent by volume and is designated below as C ₁ . 100 mg/Nm ³ of styrene has a capacity of C ₁
Equivalent to 179ppm. During the first 30 hours of the adsorption period,
The styrene concentration in purified air is at capacity C ₁
Measured to be less than 20ppm. After 40 hours of operation, this concentration rose to 30 ppm at capacity C ₁ and after 45 hours to 50 ppm. The adsorption period therefore ended and regeneration began. At the same time the temperature of the air flow to the catalyst bed is increased to 300℃, the air flow is 1.1N
m ³ /h. The amount of absorbed material at the entrance to the floor is approx.
It is ignited at 280°C and then the hot zone moves below the floor. The hot zone is approximately below the floor.
Maximum temperature reaches 700℃ at 150mm. The hot zone reaches the outlet of the reactor after about 1 hour. The styrene concentration in the air exiting the reactor at the beginning of regeneration was 30 ppm by volume of _C1 . For about 17 minutes at the beginning of the regeneration phase, the _styrene concentration is approximately
It rose to 1000ppm. This is the upper limit that a hydrocarbon analyzer can measure. After 40 minutes, the styrene concentration decreased again below 1000 ppm in C ₁ volume, and in the next 10 minutes the styrene concentration dropped to 20 ppm in C ₁ volume.
Regeneration therefore lasted a total of 50 minutes. The experiment was repeated three times and the results were essentially as described above. The calculation of the experimental data shows that the adsorption capacity under the operating conditions used is approximately 25 g of styrene per 1 kg of adsorbent (catalyst).
. After 45 hours of adsorption operation, several grams of adsorbent (catalyst)
Take a sample and analyze it. The sample contained 33g organic carbon per kg. Then, the sample was heated to 200°C in nitrogen.
heat treated. After maintaining this temperature for 2 hours,
Analyze the sample again. The concentration of organic carbon was determined to be 15 g/Kg of adsorbent (catalyst). It must be assumed that this amount of organic carbon corresponds to more or less adsorbed styrene in polymerized form. Example 3 In this experimental series consisting of four individual experiments, the reactor was placed as a 40 cm high floor of 1.6
(1.5Kg) air flow to adsorbent (catalyst) bed is 4.0N
m ³ /h. The air stream was contaminated with a hydrocarbon mixture having a boiling point range of 240-270°C, typically used as a solvent in Heatset offset printing. The temperature and hydrocarbon concentration in the air stream at the inlet to the adsorbent (catalyst) bed (Z=0) are shown in Table 2 below.

Table: The hydrocarbon concentration in the outlet stream from the reactor was determined as ppm by volume of C ₁ on a hydrocarbon analyzer. Figure 3 is a graph graphically showing the hydrocarbon concentration in ppm by volume of C ₁ as a function of time in four experiments, often the maximum allowed to be released to the atmosphere. A line is drawn indicating a concentration of 20 mgC/Nm ³ . From FIG. 3 it can be seen that the adsorption capacity in the temperature intervals studied is highly temperature dependent as a small temperature increase or decrease causes a strong decrease or increase (respectively) in the adsorption capacity. Prior to this experimental series, the adsorbent (catalyst) had been used in 10 adsorption and regeneration cycles. There, the maximum temperature during regeneration was in the range 900-920°C; ie, the limit of 800-850°C specified above provides a sufficient safety margin. The adsorption capacity was measured during an additional 10 adsorption and regeneration cycles. No significant decrease in adsorption capacity was observed. In experiment 2, the adsorption phase ended after 6 1/2 hours;
Playback has started. At this point, the adsorbent (catalyst) adsorbed a total of 39 g of hydrocarbons (equivalent to 26 g/Kg) according to calculations. The progress of regeneration carried out in clean air is shown in FIG. The time from the start of playback is shown in minutes on the horizontal axis. The left vertical axis shows the concentration of methane equivalent in the air stream from the reactor, and the right vertical axis shows the temperature at various depths Z in the adsorbent (catalyst) bed. Since the length of the floor is 40cm, Z=
0 corresponds to the floor entrance and Z=40 corresponds to the floor exit. The temperature at Z=0 is equal to the temperature of the air stream used for regeneration; the temperature at Z=40 is equal to the temperature of the air stream leaving the reactor. From FIG. 4 it can be seen that for about the first 10 minutes the temperature of the regeneration air was about 290°C and for the remaining time of the regeneration the temperature was about 100°C. From the figure,
It can be seen that the maximum temperature in the bed, approximately 930°C, was observed at a depth of 10 cm. Corresponding regeneration with a small amount of adsorbent shows that about 15 g of hydrocarbon such as 1 Kg of adsorbent will give a maximum temperature in the bed of about 825°C. In about 20 minutes, the hydrocarbon concentration in the outlet air decreases to less than 10 ppm at ₁ volume of C, as can be seen from the figure.
Playback will end after 30 minutes. During the last 10 minutes of regeneration, the adsorbed was completely oxidized on the adsorbent (catalyst). During the entire period of regeneration, usually about half of the adsorbed will be oxidized on the adsorbent (catalyst), while the remainder will be carried with the air stream to the post-purification section.

[Brief explanation of drawings]

FIG. 1 is a flow diagram of an apparatus according to the invention. FIG. 2 shows an experimental setup in which certain experiments were performed to illustrate the method implemented in the device according to the invention. FIGS. 3 and 4 are graphs showing the experimental results. In FIG. 1, the numbers indicate the following. 10:
Pipe, 18: Adsorbent (catalyst), 22: Common pipe,
42: pipe, 44: pipe, 42〓,46〓...46〓:
Branch pipe, 48〓, 48〓...48〓: Reactor, 50〓,
50〓...50〓: Pipe, 52: Pipe, 54〓,54〓...
...54〓: Branch pipe, 56〓, 56〓...56〓: Pipe, 58: Common pipe, 60: Combustion chamber, 62: Burner, 64: Junction, 66: Recirculation, 68: Pipe, 7
0: tube, 72: confluence, 74: tube, 76: reactor. In Figure 2, the numbers indicate the following. 10:
Tube, 16: Reactor, 18: Adsorbent (catalyst), 2
0: Pipe, 22: Pipe, 78: Flowmeter, 80: Valve, 82: Pipe, 84: Preheater, 88: Pipe, 9
0: Pipe, 92: Pump, 94: Pipe, 96: Heating coil, 98: Temperature measurement tube, 100: Control valve, 1
02: Hydrocarbon analyzer. In FIG. 3, the horizontal axis shows time and the vertical axis shows the hydrocarbon concentration in ppm by C ₁ capacity. In Figure 4, the horizontal axis represents time (minutes),
The left vertical axis shows the hydrocarbon concentration in ppm by volume of C ₁ and the right vertical axis shows the temperature.

Claims (1)

Claims: 1. (a) at least two first reactors 48〓, 48〓, 48〓, 48〓, 48〓, each having a layer 18 of adsorbent which is active as an oxidation catalyst at high temperatures;
48〓, supply pipes 10, 42, 44, 46〓, 46 for supplying the gas to be treated to the first reactor
〓, 46〓, 46〓, 46〓 and 46〓 and a discharge pipe 22 for purifying gas from the first reactor, and (b) a second reactor having the same adsorbent (catalyst) as the first reactor. , the first reactor under regeneration is connected to a second reactor 76 by conduits 58 from all first reactors, which conduit 58 has a combustion chamber 60 to which a burner 62 is connected; Supply pipe 68 supplying hot gas to the second reactor
The second reactor 76 has an outlet pipe 70 for the thermally purified gas, which is connected to an exhaust pipe 74 for discharging a portion of the thermally purified gas from the apparatus. In an apparatus for continuously removing oxidizing contaminants from a gas, particularly air, () a recirculation pipe 66 for recirculating a thermally purified gas stream from an outlet pipe 70 to a junction 64 in conduit 58; The purified gas stream is transferred from the second reactor 76 to the first reactor 48〓, 48〓, 48〓, 48〓, 48〓, 4
Recirculation pipes 52, 54, 54 for recirculating to 8
〓, 54〓, 54〓, 54〓, 54〓.