KR20010085967A - Method and device for recovering hydrocarbon vapor - Google Patents

Abstract

The hydrocarbon vapor recovery method may include a first step of removing a portion of hydrocarbon vapor by cooling and condensing a gas containing hydrocarbon vapor with a first heat exchanger (11); A second step of heating and heating the gas from which a part of hydrocarbon vapor is removed by a second heat exchanger (14); And a third step of supplying the heated gas to the adsorption towers 15 and 16 filled with the adsorbent, where the hydrocarbon vapor is adsorbed and removed. Hydrocarbons are separated from the adsorbent by depressurizing the interior of the adsorption towers 15 and 16 and by flowing clean gas back into the adsorption towers 15 and 16.

Description

Hydrocarbon vapor recovery method and recovery device {METHOD AND DEVICE FOR RECOVERING HYDROCARBON VAPOR}

When filling a liquid hydrocarbon such as gasoline, kerosene or diesel into a barge, lorry, or storage tank, gas such as gaseous phase and liquid phase are replaced in the container, or air, such as air present in the container, expands in response to a change in temperature, thereby allowing hydrocarbon vapors (liquid Some components of the hydrocarbons are volatilized to produce a gas, including vapor). The hydrocarbon vapor concentration in the off-gas reaches 30% in summer.

Recently, the emissions of such hydrocarbon vapors are regulated. For example, according to the metropolitan government's pollution prevention ordinance, the concentration limit is 5 to 8%, and the removal rate is limited to 80 to 90%. In addition, regulations on hazardous pollutant atmospheres have been tightened.

Conventionally, the following methods have been proposed as a method for recovering hydrocarbon vapor in a storage tank discharge gas: (1) After adsorbing hydrocarbon vapor by using a removal device filled with activated carbon, the hydrocarbon adsorbed by heating steam is separated. (2) a method of adsorbing hydrocarbon vapor using a removal device packed with silica gel or zeolite, and then depressurizing to separate the adsorbed hydrocarbon, and (3) a membrane separation method.

On the other hand, in order to improve the recovery efficiency of the conventional hydrocarbon vapor recovery method, the following invention has been proposed (Japanese Patent Laid-Open No. 10-156127).

In the present invention, the exhaust gas containing the high concentration of benzene in the recovery column is contacted with pre-cooled heavy oil or benzene to remove some of the benzene vapor, and then the benzene vapor is adsorbed and removed in the adsorption tower filled with the adsorbent. When the benzene is separated from the adsorbent, the adsorption column is separated by a vacuum pump or the like while being heated by a heating coil in which steam flows. The separated benzene is recycled to the recovery column and recovered by condensation.

According to the above invention, since some of the benzene vapor is recovered and then adsorbed in the adsorption tower, the benzene can be almost completely removed and the post-treatment of the separated benzene is easy.

However, a method of heating the adsorption tower by using a heating coil through which steam flows when separating benzene from the adsorbent is adopted, but such an indirect heating method is not preferable in terms of thermal efficiency. Moreover, the adsorbent such as silica gel has a low thermal conductivity and the contact of each particle is made in point contact, so that the thermal conductivity of the adsorbent packed layer is extremely poor.

In normal pressure and temperature swing adsorption (PTSA), the adsorption / separation conversion is performed for about several minutes, so within that time, a distance of several centimeters near the surface of the heating coil is practically achieved. Only can raise the temperature. Therefore, a large number of heating coils must be provided, thereby requiring an extra space in the adsorption tower and uneven temperature of the adsorbent layer, resulting in a large loss of heating steam.

Summary of the Invention

An object of the present invention is to provide a method and apparatus for recovering a hydrocarbon vapor capable of efficiently recovering the hydrocarbon vapor from a gas containing a hydrocarbon vapor.

The method for recovering hydrocarbon vapor of the present invention comprises: a first step of cooling and condensing a hydrocarbon vapor-containing gas with cooling means to remove a portion of the hydrocarbon vapor; A second step of heating up the gas from which some of the hydrocarbon vapors have been removed by heating means; And supplying the heated gas to an adsorption means filled with an adsorbent to adsorb and remove hydrocarbon vapors.

The temperature of the gas after the treatment in the first step is preferably adjusted to a low temperature above the freezing point of the containing component and preferably close to the freezing point.

The lower the temperature is, the lower the temperature is, because the condensation amount increases and the concentration of hydrocarbon vapor in the gas decreases, so that the load at the rear end is reduced and the adsorption tower serving as the adsorption means can be made smaller. For example, when benzene is a main component of hydrocarbon vapor, since the freezing point of benzene is 5.5 degreeC, temperature becomes like this. Preferably it is 6-20 degreeC, More preferably, it is 6-10 degreeC.

By this first step process, for example, high-boiling impurities such as toluene, xylene, trimethylbenzene, coumarone and indene contained in crude oil or diesel oil mainly composed of benzene generated by the dry distillation of coal, especially naphthalene, which is a sublimable solid, It is effectively removed by lowering the vapor pressure by cooling and dissolving in benzene.

It is preferable to adjust the gas temperature after heating in a 2nd step to the temperature which is 5-30 degreeC higher than the temperature after processing by a preceding 1st step process. More preferably, the temperature is 10-20 ° C. high.

Adjusting to such a temperature immediately condenses or solids when the temperature is further lowered during piping or in an adsorption tower or by winter heat radiation because the hydrocarbon vapor is saturated at the cooled temperature in the first stage of treatment. Precipitation occurs. This phenomenon causes a blockage of the pipe, a malfunction of the on-off valve or an increase in the pressure loss of the adsorption tower.

On the other hand, since the gas after the first step can be heated up by the second step process, it is possible to lower the saturation degree of the hydrocarbon vapor and make it difficult to cause condensation in piping or the like. In addition, the temperature of the adsorption device of the rear stage can be raised to facilitate separation and regeneration after adsorption. Furthermore, by lowering the concentration of hydrocarbon vapors, the load of the next third stage is reduced, which makes it possible to miniaturize the adsorption tower or the vacuum pump.

On the other hand, the adsorbent in the adsorption tower in the next third step increases the temperature by adsorption of hydrocarbon vapor, and the temperature decreases by separation. When the amount of adsorption is several%, the change in temperature is several degrees Celsius. Therefore, immediately after the operation of separating the hydrocarbon vapor from the adsorbent without performing the second step of heating and raising the temperature, the gas containing the saturated vapor of the hydrocarbon vapor is introduced when the temperature of the adsorbent decreases. Condensation or solid precipitation may occur. On the contrary, if the temperature of the gas to be introduced is too high, the adsorption capacity decreases, so that the adsorption efficiency decreases.

As the adsorbent filled in the adsorption means of the third stage, a general adsorbent such as silica gel, zeolite, alumina gel or activated carbon may be used. From the viewpoint of safety, the use of silica gel, zeolite and alumina gel is preferred.

More preferred adsorbents are silica gels treated with hot calcined or hydrophobized agents or higher silica zeolites having a silica / alumina ratio of at least 80. When the adsorbent adsorbs water in the gas, it is necessary to separate the water from the recovered oil. Therefore, a hydrophobic adsorbent that adsorbs hydrocarbons without adsorbing moisture is preferable.

The said adsorption means is an adsorption tower, for example.

In the third step, the hydrocarbon vapor is adsorbed and removed by the adsorbent to remove the clean gas.

In addition, the adsorbent which adsorb | sucked hydrocarbons in a 3rd step separates and recycles hydrocarbons by pressure reduction. The vacuum degree at the time of separation is preferably 60 Torr or less in absolute pressure. More preferably, it is 25 Torr or less in absolute pressure. The lower the absolute pressure, the easier the separation of the hydrocarbon vapors is. If the separation of hydrocarbons from the adsorbent is insufficient, the hydrocarbon vapor becomes difficult to adsorb to the adsorbent in the next adsorption operation, so that the hydrocarbon vapor removal efficiency is lowered.

On the other hand, the hydrocarbon vapor separated from the adsorbent is very high in concentration and can be easily condensed by cooling to be recovered as a liquid. As a cooling method, a general heat exchanger (tube type, plate type, etc.) can be used. In addition, low concentration hydrocarbon vapors, which could not be condensed, can be mixed with the raw material gas at the inlet of the apparatus and treated without discharging outside the apparatus.

Other methods for recovering hydrocarbon vapor include cooling condensation by contact with cooled diesel, kerosene, gasoline and recovered oil or the like, or dissolving and recovering them. In addition, the low concentration hydrocarbon vapor which cannot be condensed or dissolved can be mixed with the raw material gas at the inlet of the apparatus as described above.

The separated hydrocarbon vapor may also be mixed with the gas containing the hydrocarbon vapor of the first stage to be cooled and condensed and recovered.

In addition, since the target gas for recovering the hydrocarbon vapor may be an inert gas such as nitrogen in addition to the normal air, the present invention can be applied to various gases discharged from a production or storage facility of a liquid hydrocarbon which is a source of hydrocarbon vapor.

In the recovery method of the present invention, it is preferable to use the liquid hydrocarbon condensed in the first step to contact the cooled liquid hydrocarbon with a gas containing hydrocarbon vapor to cool and condense the hydrocarbon vapor in the gas.

In this way, since the condensed liquid hydrocarbon is used, efficient recovery is possible.

In the recovery method of the present invention, it is preferable to use hot water as a heat medium for heating the gas from which a part of the hydrocarbon vapor is removed in the second step.

That is, when steam is used as the heat medium, since the temperature difference from the processing gas is large, there is a possibility of causing poor heating or abnormal temperature increase when changing the processing gas flow rate, which is not suitable. On the other hand, when hot water is used as the heat medium, there is no such problem. In addition, it is not a problem to use hot water heated by steam through a heat exchanger.

In the recovery method of the present invention, in the third step, the gas heated in the second step is supplied to the adsorption means to adsorb the hydrocarbon vapor to the adsorbent, and the inside of the adsorption means is depressurized and clean gas (usually Air or a suitable gas) is preferably flowed back to separate the hydrocarbons from the adsorbent in this state.

In this way, when the hydrocarbons are separated from the adsorbent, the partial pressure of the hydrocarbon vapor is lowered by backflowing the clean gas inside the outlet side of the adsorption tower, so that the hydrocarbons are easily separated from the adsorbent.

In this case, as the flow rate of the clean gas is increased, the hydrocarbons are more likely to be separated, but if it is simply increased, the concentration of hydrocarbon vapor in the separation gas decreases, making it difficult to recover by cooling condensation in the subsequent process. Therefore, an optimum value exists in the flow rate of the clean gas, and is preferably 1/5 to 1/50, more preferably 1/10 to 1/20, based on the flow rate of the processing gas introduced into the adsorption column at the time of adsorption. .

In the recovery method of the present invention, it is preferable that a plurality of adsorption means are provided, and the adsorption means alternately repeats the adsorption treatment and the separation treatment continuously.

The adsorption means is preferably switched within 1 hour, more preferably within 10 minutes. In order to reduce the temperature change of an adsorbent layer by making the change of the adsorption amount of hydrocarbons small, switching of a short time is preferable.

In general, adsorption is an exothermic reaction, so that adsorption is unlikely to occur when the temperature rises (separation easily occurs), and conversely, adsorption easily occurs when the temperature decreases (separation hardly occurs). Therefore, when the hydrocarbon vapor is adsorbed, the temperature of the adsorbent is increased, so that further adsorption of the hydrocarbon vapor is difficult. On the contrary, even in the separation operation, when the hydrocarbon vapor is separated, the temperature decreases, so that further separation of the hydrocarbon vapor becomes difficult. In other words, if the adsorption / separation operation is performed, a phenomenon occurs in a direction that negates the effect of the operation. Therefore, in order to reduce such influence, it is effective to shorten the switching time of the adsorption treatment and the separation treatment.

In the recovery method of the present invention, it is preferable that the hydrocarbon separated from the adsorbent is mixed with the gas containing the hydrocarbon vapor of the first stage, cooled and condensed to recover.

Since the separated hydrocarbons are very high in concentration and easily condensed, they can be easily recovered because they are simply condensed when mixed with the gas of the first stage. This method is economically advantageous as the cooling condensation and recovery system is integrated into one.

The apparatus for recovering hydrocarbon vapor of the present invention includes cooling means for cooling and condensing a hydrocarbon vapor-containing gas to remove a portion of the hydrocarbon vapor, heating means for heating and heating the gas from which a portion of the hydrocarbon vapor has been removed, And adsorption means filled with an adsorbent for adsorption and removal of hydrocarbon vapors.

The cooling means is selected from the following two according to the concentration of the hydrocarbon vapor or the allowable pressure loss.

If the allowable pressure loss is high, a combination of ordinary heat exchangers (tube, plate, etc.) and gas-liquid separators is suitable.

If the allowable pressure loss is low, a recovery tower with a heat exchanger or a recovery tower with an external heat exchanger is suitable.

The recovery tower is provided with a gas-liquid contact portion at the upper portion and an accumulator at the lower portion, and the liquid at the lower portion is pumped out and introduced to the upper portion for circulation.

The gas-liquid contact portion is filled with a filler such as a Raschig ring, so that the gas-liquid contact can be efficiently performed.

The liquid level in the collection portion is controlled by the balance of the pumped amount and the circulation amount.

It is preferable to install a demister at the outlet of the gas of the recovery tower to prevent entrainment.

As the heating means, ordinary heat exchangers such as tube type and plate type can be used.

In the recovery apparatus of the present invention, it is preferable to provide a common chiller unit as a supply source of the cooling medium supplied to the cooling means and a source of the heating medium supplied to the heating means.

If a common refrigeration unit is used, it is economical and advantageous in terms of space because one unit can supply the cooling heat medium and the heating heat medium, respectively.

Moreover, you may use another refrigerator or a heater as said cooling means and a heating means.

In the recovery apparatus of the present invention, it is preferable that a plurality of the adsorption means are provided in order to alternately switch between the adsorption treatment and the separation treatment to perform the continuous treatment.

For example, the adsorption tower, which is an adsorption means, may be a single tower, but it is preferable to install a plurality of adsorption towers to switch adsorption / separation operations to perform adsorption treatment continuously.

The present invention relates to a method for recovering hydrocarbon vapor contained in a gas such as air discharged from a storage facility when a liquid hydrocarbon such as gasoline is charged to a storage facility such as a storage tank or the liquid hydrocarbon expands in response to a change in temperature. It relates to a device for this.

1 is a schematic diagram of an apparatus for recovering hydrocarbon vapor according to a first embodiment of the present invention.

2 is a schematic diagram of an apparatus for recovering hydrocarbon vapor according to a second embodiment of the present invention.

3 is a schematic view of a hydrocarbon vapor recovery apparatus according to a comparative example.

4 is a schematic view showing the main parts of a hydrocarbon vapor recovery apparatus according to another embodiment of the present invention.

5 is a schematic view showing the main part of an apparatus for recovering hydrocarbon vapor according to another embodiment of the present invention.

6 is a schematic view showing the main part of a hydrocarbon vapor recovery apparatus according to another embodiment of the present invention.

[First Embodiment]

Referring to Fig. 1, a method for recovering a hydrocarbon vapor and an apparatus thereof according to the first embodiment of the present invention will be described.

The apparatus for recovering hydrocarbon vapor of the present embodiment includes a gas supply line (10A) connected to a first heat exchanger (11) and a heat exchanger (11) connected to an introduction line (10) of a gas containing hydrocarbon vapor (here, air). Gas supply in which the downstream side is branched to the second heat exchanger 14 and the second heat exchanger 14 connected to the gas-liquid separator 13 and the gas-liquid separator 13 connected to the gas-liquid separator 13 through the gas supply line 12 First and second adsorption towers 15 and 16 connected via line 12A and vacuum connected via gas supply line 33A branched from the vicinity of adsorption towers 15 and 16 of gas supply line 12A. The pump 20 is provided.

The refrigerator 17 is attached to the said 1st heat exchanger (tube type or plate type) 11.

At the bottom of the gas-liquid separator 13 there is a collecting part 19. At the outlet portion of the gas of the gas-liquid separator 13, a wire-mesh-type demister (not shown) is provided.

A heater 21 is attached to the second heat exchanger (tube type or plate type) 14. The heating medium of this heat exchanger 14 is hot water.

The said 1st and 2nd adsorption towers 15 and 16 have the adsorption layer 22 in which the adsorbent was filled.

First and second valves 23 and 24 are provided in each gas supply line 12 from the second heat exchanger 14 to the first and second adsorption towers 15 and 16.

The third and fourth valves 25 and 26 are installed in the gas supply line 33A branched from the gas supply line 12A.

In the first and second adsorption towers 15 and 16, discharge lines 31 of clean gas are connected to the tower portions, respectively, and fifth and sixth valves 27 and 28 are connected to the lines 31, respectively. It is installed.

In addition, in the line 31 between the fifth and sixth valves 27 and 28 and the top portion of the adsorption towers 15 and 16, a clean gas (here, clean air) is flowed back to each of the adsorption towers 15 and 16. The supply line 32 of air is connected, and the 7th and 8th valves 29 and 30 are provided in each line.

Between the vacuum pump 20 and the introduction line 10 in front of the first heat exchanger 11, a return line 33 for returning the separated hydrocarbon vapor is provided.

The procedure for recovering hydrocarbon vapor using this recovery device is as follows.

First, in the first step, air containing hydrocarbon vapors is passed from the inlet line 10 to the first heat exchanger 11, where the air is cooled to condense the hydrocarbon vapors, and the cooled condensed hydrocarbons and air It is supplied to the gas-liquid separator 13 to separate gas-liquid. Part of the hydrocarbon vapor that has been condensed is collected in the collecting part 19 and recovered. On the other hand, air containing the remaining hydrocarbon vapor is supplied to the second heat exchanger 14 from the outlet.

Next, in the second step, hot water is used as the heat medium of the second heat exchanger 14 to heat and raise the air from which a part of the hydrocarbon vapor has been removed.

Next, in the third step, the heated air is supplied to the first or second adsorption towers 15 and 16, where the hydrocarbon vapor is adsorbed and removed by the adsorbent.

In these first and second adsorption towers 15 and 16, the adsorption treatment and the separation treatment are alternately switched by opening and closing the valves 23, 24, 27 and 28 to continuously process the hydrocarbon vapor.

In the separation process, the vacuum pump 20 depressurizes the interior of the adsorption tower 15, 16, and backs the clean air along the supply line 32 of the clean air into the adsorption tower 15, 16 to adsorb the hydrocarbon in this state. Separate from.

The separated hydrocarbon is returned to the inlet side of the heat exchanger 11, mixed with air containing hydrocarbon vapor, and cooled and condensed and recovered by repeating after the first step described above.

Second Embodiment

Referring to Fig. 2, a method for recovering hydrocarbon vapor and an apparatus thereof according to the second embodiment of the present invention will be described.

The apparatus for recovering hydrocarbon vapor of the present embodiment includes a recovery tower 36 connected to an introduction line 10 of gas (here, air) containing hydrocarbon vapor, and a liquid hydrocarbon between the lower part and the upper part of the recovery tower 36. First heat exchanger 11 provided with a circulation line 39 between the second heat exchanger 11 and a second heat exchanger 14 connected to the recovery tower 36 through a gas supply line 12. 14, the first and second adsorption towers 15 and 16 connected downstream through the gas supply line 12A having two branches, and branched from the vicinity of the adsorption towers 15 and 16 of the gas supply line 12A. The vacuum pump 20 connected through the gas supply line 33A is provided.

The recovery tower 36 is provided with a gas-liquid contact portion 37 at the upper portion and a liquid collection portion 38 at the lower portion. The gas-liquid contact portion 37 is filled with a filler such as a Raschig ring. A wire-mesh demister (not shown) is provided at the outlet of the gas of the recovery tower 36.

One end of the circulation line 39 of the liquid hydrocarbon is connected to the collection part 38 side of the recovery tower 36, and the other end is inserted above the gas-liquid contact part 37 in the recovery tower 36. The part is equipped with the spreader 41 of a liquid hydrocarbon. The circulation pump 42 is provided between the collection part 38 of this circulation line 39 and the 1st heat exchanger 11.

Other components in this apparatus, such as the first heat exchanger 11, the second heat exchanger 14, the first and second adsorption towers 15 and 16, the vacuum pump 20, and the like, are described in the first embodiment. Same as

The procedure for recovering hydrocarbon vapor using this recovery device is as follows.

First, in the first step, air containing hydrocarbon vapor is supplied from the inlet line 10 to the recovery tower 36, where the air is cooled to condense the hydrocarbon vapor, and the resulting liquid is collected into the collecting part 38. Collect. When the air is cooled and condensed, the liquid hydrocarbon of the liquid collection part 38 is partially circulated through the circulation line 39, cooled by the first heat exchanger 11, and then supplied into the recovery tower 36. The gas-liquid contacting portion 37 makes contact with the liquid hydrocarbon and the air.

This next second and third steps are the same as in the first embodiment.

In the first and second embodiments, the heater 21 is provided in the refrigerator 17 and the second heat exchanger 14 in the first heat exchanger 11, but is supplied to the first heat exchanger 11. A conventional refrigeration system unit can be provided as a source of cooling medium to be cooled and a source of heating medium to be supplied to the second heat exchanger 14.

In addition, the recovery tower 36 may be configured as follows.

As shown in FIG. 4, between the gas-liquid contact portion 37 of the recovery tower 36 and the introduction portion of the circulation line 39, a gas-liquid diffuser 37A such as a chimney tray or a perforated tray is provided, and the circulation line ( The demister 37B is provided in the upper part of the introduction part of 39). In addition, the liquid collection part 38 is connected to an extraction line 42A extending from the side of the recovery tower 36 to the circulation pump 42, and the suction end thereof is directed downward, and a plurality of radially arranged around it is provided. The vortex breaker 42B which consists of a board | plate material of this is mounted.

By installing the gas-liquid disperser 37A, additional contact between the liquid component returned from the circulation line 39 and the gaseous component rising through the gas-liquid contact portion 37 can be made, and the recovery of the liquid component can be promoted. In addition, by installing the demister 37B, the misty liquid component can be removed from the gas discharged from the overhead gas supply line 12. In addition, by providing the vortex breaker 42B, the occurrence of swirling and gas curling when the liquid component accumulated in the collection part 38 in the extraction line 42A is sucked is avoided.

The specific structures of the gas-liquid disperser 37A, the demister 37B, and the vortex breaker 42B may be employed in a timely manner as the structure used in the existing factory technology.

As shown in Fig. 5, a substantially U-shaped recovery tower 36A may be employed. In the drawing, the introduction line 10 is connected to one top top (left side in the drawing) of the substantially U-shaped recovery tower 36A, and the circulation line 39 is connected slightly below the top top. The gas-liquid dispersion machine 37A is provided slightly below the connection part of the circulation line 39, and the gas-liquid contact part 37 is provided below it. The gas supply line 12 is connected to the other top top (right side in drawing), and the demister 37B is provided in the lower part. The structure of the recovery tower 36A is the same as that of FIG. 4 except for the wide bottom portion.

Also by this substantially U-shaped recovery tower 36A, the hydrocarbon vapor contained in the gas from the introduction line 10 and the circulation line 39 is isolate | separated, and the gas from which the hydrocarbon vapor was isolate | separated from the gas supply line 12 is carried out. It can be withdrawn and collected in the collection part 38.

Each of the above embodiments was to treat hydrocarbon vapor containing gas from one inlet line 10, but it is also possible to treat hydrocarbon vapor containing gas from multiple gas sources. In such a case, it is preferable to supplement the structure which avoids mixing contamination by countercurrent or the like between the respective gas sources.

In FIG. 6, two lines of introduction lines 10L and 1OH are connected to the recovery tower 36A. The introduction line 10L is connected to the top top like the introduction line 10 of FIG. 5. The introduction line 10H is connected between the gas-liquid contact portion 37 of the recovery tower 36A and the gas-liquid dispersion machine 37A.

Here, the gas source supplied to the introduction line 10H is higher in concentration or purity of the liquid stored and stored than the gas source supplied to the introduction line 10L. For example, the introduction line 10L is connected to the exhaust port of the crude benzene tank, and the introduction line 10H is connected to the exhaust port of the pure benzene tank.

In this case, if the introduction line 10H is simply connected to the recovery tower 36A, since the low purity benzene component from the introduction line 10L is introduced into the recovery tower 36A, this low purity benzene component is introduced. It can flow back to the pure benzene tank via line 10H, causing a decrease in the benzene purity in the tank.

Therefore, a sealing port 10P is provided in the inlet portion of the inlet line 10H to store and hold the contents liquid (here, pure benzene) of the gas source connected through the inlet line 10H therein. Moreover, the edge part of the introduction line 10H is dipped in the liquid phase in the sealing opening 10P.

Thereby, backflow in the introduction line 10H can be prevented.

In addition, many gas sources are not limited to homogeneous ones, and may be other kinds, such as gasoline and benzene, if the object of recovery is duplicated.

Hereinafter, the specific example performed according to each embodiment mentioned above is demonstrated.

Example 1

In the said 1st Embodiment, the specific example in a method and an apparatus is as follows.

The flow rate of air containing a high concentration of hydrocarbon vapor to be treated (hereinafter referred to as raw material gas) was 10 m ³ , and the concentration of hydrocarbon vapor was 20% by volume. The components of the hydrocarbon vapor in the air were as shown in Table 1 below.

Type of hydrocarbon Pentane benzene toluene xylene Trimethyl benzene Inden naphthalene Concentration (% by volume) 2.5 15.0 1.5 0.5 0.2 0.1 0.2

First, the raw material gas and the separation gas from the outlet of the vacuum pump 20 are combined, cooled by a tube type first heat exchanger 11, condensed a part of the gas, and introduced into a water-based gas-liquid separator 13. Separated into gas and liquid phase.

The temperature of the gas after cooling with the 1st heat exchanger 11 was 10 degreeC. In addition, the amount of liquid hydrocarbon recovered was 3.9 kg / hr.

Next, the gas discharged from the gas-liquid separator 13 was introduced into a tubular second heat exchanger 14 and heated up. The temperature of the gas after heating with the said heat exchanger 14 was 30 degreeC.

Subsequently, the heated gas was supplied to one of the two adsorption towers 15, where the hydrocarbon vapor was adsorbed and removed by the adsorbent. The used adsorbent was hydrophobized by firing silica gel (Silicasia Chemical Co., Ltd. silica gel CARiACT Q-3 (trade name)) at 500 ° C for 4 hours. In the two adsorption towers 15 and 16, the inlets and outlet valves 23, 24, 27 and 28 were opened and closed every 5 minutes to alternately adsorb and separate.

The concentration of hydrocarbon vapor in the gas at the outlet of the adsorption towers 15 and 16 was 30 ppm. In addition, the components of the hydrocarbon vapor were as shown in Table 2 below.

Type of hydrocarbon Pentane benzene toluene xylene Trimethyl benzene Inden naphthalene Concentration (% by volume) 0.002 0.001 0 0 0 0 0

By depressurizing the inside of the adsorption towers 15 and 16 with the vacuum pump 20, an operation of separating hydrocarbons from the adsorbents of the adsorption towers 15 and 16 was performed. The separation pressure at this time is 25 Torr in absolute pressure. Separation was carried out from the outlets of the adsorption towers 15 and 16 through the supply line 32 of clean air while the clean air was flowed back at a flow rate of 1 m ³ / hr.

Separation gas from the outlet of the vacuum pump 20 joined the raw material gas of the introduction line 10, and it cooled and condensed with the 1st heat exchanger 11, and was collect | recovered.

The temperature of the adsorbent at the time of adsorption / separation was measured by the thermocouple inserted in the adsorption towers 15 and 16, and it was 35 degreeC at the time of adsorption, and 25 degreeC at the time of separation.

During operation, the pressure loss of the adsorption towers 15 and 16 was constant as 20 mmH ₂ O. After the operation, the adsorption towers 15 and 16 and the pipes were checked for opening, but no abnormalities such as condensation of hydrocarbon vapors were observed.

Example 2

In said 2nd Embodiment, the specific example in a method and an apparatus is as follows.

The air containing the high concentration hydrocarbon vapor to be treated is the same as in Example 1.

First, the raw material gas and the separation gas from the outlet of the vacuum pump 20 were combined and introduced into the aqueous recovery tower 36. The liquid from the liquid collection part 19 of the recovery tower 36 is extracted by the pump 42, cooled by a tubular first heat exchanger 11, introduced into the upper part of the recovery tower 36, and brought into contact with the raw material gas. The hydrocarbon vapor in the source gas was condensed. The temperature of the gas after cooling by the heat exchanger 11 was 10 degreeC.

Here, the gaseous phase and the liquid phase after gas-liquid contact were separated, and the gaseous phase was discharged from the upper part of the recovery tower 36, and the liquid phase was recovered to the lower liquid collecting part 38. The amount of liquid hydrocarbon recovered was 3.9 kg / hr.

Next, the gas discharged | emitted from the recovery tower 36 was introduce | transduced into the plate-type 2nd heat exchanger 14, and it heated up and heated. The temperature of the gas after heating with this heat exchanger 14 was 25 degreeC.

Next, the heated gas was supplied to one of the two adsorption towers 15, where the hydrocarbon vapor was adsorbed and removed by the adsorbent. The adsorbent used was hydrophobized by firing silica gel [silica gel CARiACT Q-6 (trade name) manufactured by Fuji Silysia Chemical Co., Ltd.] at 500 ° C. for 4 hours. In the two adsorption towers 15 and 16, the inlet and outlet valves 23, 24, 27 and 28 were opened and closed every 5 minutes to alternately adsorb and separate.

The concentration of hydrocarbon vapor in the gas at the outlet of the adsorption towers 15 and 16 was 30 ppm. In addition, the components of the hydrocarbon vapor were as shown in Table 3 below.

Type of hydrocarbon Pentane benzene toluene xylene Trimethyl benzene Inden naphthalene Concentration (% by volume) 0.002 0.001 0 0 0 0 0

The inside of the adsorption tower 15, 16 was decompressed by the vacuum pump 20, and the operation which isolate | separates hydrocarbon from the adsorbent of the adsorption tower 15, 16 was performed. The separation pressure at this time is 20 Torr in absolute pressure. The separation was carried out from the outlets of the adsorption towers 15 and 16 through the supply line 32 of clean air, with the clean air flowing backward at a flow rate of 0.5 m ³ / hr.

Separation gas from the outlet of the vacuum pump 20 joined the raw material gas of the introduction line 10, and it cooled and condensed by the recovery tower 36, and was collect | recovered.

The temperature of the adsorbent at the time of adsorption / separation was measured by the thermocouple inserted in the adsorption towers 15 and 16, and it was 30 degreeC at the time of adsorption, and 20 degreeC at the time of separation.

During operation, the pressure loss of the adsorption tower (15, 16) was constant at 20 mmH ₂ 0. After the operation, the adsorption tower (15, 16) and the pipe were opened and checked, but no abnormalities such as condensation of hydrocarbon vapor were observed.

Comparative Example 1

As shown in FIG. 3, the apparatus according to the present comparative example excludes the second heat exchanger 14 from the apparatus according to the second embodiment, and removes the heating coil 45 through which steam flows through the adsorption towers 15 and 16. The heater 46 which has is provided.

The air containing the high concentration hydrocarbon vapor to be treated is the same as in Example 1.

First, the raw material gas and the separation gas from the outlet of the vacuum pump 20 were combined and introduced into the water recovery column 36. The liquid from the collection part 38 of the recovery tower 36 is discharged by the pump 42, cooled by the first tubular heat exchanger 11, introduced into the upper part of the recovery tower 36, and brought into contact with the raw material gas. The hydrocarbon vapor in the source gas was condensed. The temperature of the gas after cooling by the heat exchanger 11 was 10 degreeC.

Here, the gaseous phase and the liquid phase after gas-liquid contact were separated, and the gaseous phase was discharged from the upper part of the recovery tower 36, and the liquid phase was recovered to the lower liquid collecting part 38. The amount of liquid hydrocarbon recovered was 3.9 kg / hr.

Next, the gas discharged from the recovery tower 36 was supplied to one of the two adsorption towers 15 to adsorb and remove hydrocarbon vapor with an adsorbent. The used adsorbent was hydrophobized by firing silica gel [silica gel CARiACTQ-6 (trade name) manufactured by Fuji-Silica Chemical Co., Ltd.] at 500 ° C for 4 hours. In the two adsorption towers 15 and 16, the inlets and outlet valves 23, 24, 27 and 28 were opened and closed every 5 minutes to alternately adsorb and separate.

The concentration of hydrocarbon vapor in the gas at the outlet of the adsorption towers 15 and 16 was from 100 to 200 ppm, which tended to increase gradually. In addition, the components of the hydrocarbon vapor of the first week are shown in Table 4 below.

Type of hydrocarbon Pentane benzene toluene xylene Trimethyl benzene Inden naphthalene Concentration (% by volume) 0.12 0.06 0.02 0 0 0 0

The inside of the adsorption towers 15 and 16 were decompressed by the vacuum pump 20 to separate hydrocarbons from the adsorbents of the adsorption towers 15 and 16. The separation pressure at this time is 20 Torr in absolute pressure. The separation was performed while the clean air was flowed back from the outlets of the adsorption towers 15 and 16 at a flow rate of 0.5 m ³ / hr.

Separation gas from the outlet of the vacuum pump 20 joined with the raw material gas of the inlet of the apparatus, and was recovered by cooling condensation to the recovery tower 36.

As a result of measuring the temperature of the adsorbent at the time of adsorption / separation with a thermocouple, it was the maximum 15 degreeC at the time of adsorption, the minimum 10 degreeC at the time of separation, and the maximum 40 degreeC, and the gap in the adsorption tower (15, 16) was also large.

During one week of operation, the pressure drop of the adsorption towers 15 and 16 tended to increase slowly to 20 to 30 mmH ₂ O.

After the operation was completed, the opening of the adsorption towers 15 and 16 and the pipe were checked to check that condensation of hydrocarbon vapors was observed in the lower part of the adsorption towers 15 and 16 and near the valve in the middle of the piping.

INDUSTRIAL APPLICABILITY The present invention can be used to prevent diffusion and recovery of hydrocarbon vapors discharged from a storage tank in a storage facility for a liquid hydrocarbon such as gasoline or a treatment facility such as a refining.

Claims (9)

A first step of cooling and condensing the hydrocarbon vapor-containing gas with cooling means to remove some of the hydrocarbon vapor; A second step of heating the gas from which some of the hydrocarbon vapors have been removed by heating means; And And a third step of adsorbing and removing the hydrocarbon vapor by supplying the heated gas to the adsorption means filled with the adsorbent. The method of claim 1, In the first step, the cold condensed liquid hydrocarbon is used, wherein the cooled liquid hydrocarbon is in contact with the hydrocarbon vapor containing gas to cool the condensed hydrocarbon vapor in the gas, characterized in that for recovering hydrocarbon vapor. The method of claim 1, A method of recovering hydrocarbon vapors, characterized in that the thermal medium for heating the gas after removing some of the hydrocarbon vapors in the second step is hot water. The method of claim 1, After supplying the heated gas of the second stage to the adsorption means of the third stage to adsorb the hydrocarbon vapor to the adsorbent, the hydrocarbon is separated from the adsorbent by depressurizing the inside of the adsorption means and flowing a clean gas back into the adsorption means. A method for recovering hydrocarbon vapors. The method of claim 4, wherein A plurality of adsorption means is used in the third step, wherein the adsorption means and the separation treatment is repeated to successively repeat the adsorption treatment and separation treatment. The method of claim 4, wherein A hydrocarbon vapor recovery method, wherein the hydrocarbon separated from the adsorbent of the third stage is mixed with the hydrocarbon vapor-containing gas of the first stage and cooled and condensed to recover. Cooling means for cooling and condensing the hydrocarbon vapor containing gas to remove a portion of the hydrocarbon vapor; Heating means for heating up the gas from which a portion of the hydrocarbon vapor has been removed; And And an adsorption means filled with an adsorbent for adsorbing and removing the hydrocarbon vapor in the heated gas. The method of claim 7, wherein A refrigeration unit for hydrocarbon vapor, characterized in that a common refrigeration system unit is provided as a source of a cooling medium to be supplied to the cooling means and a source of a heating medium to be supplied to the heating means. The method of claim 7, wherein And a plurality of adsorption means for alternately and continuously treating the adsorption treatment and the separation treatment in the adsorption means.