WO2000025900A1

WO2000025900A1 - Method and device for recovering hydrocarbon vapor

Info

Publication number: WO2000025900A1
Application number: PCT/JP1999/005899
Authority: WO
Inventors: Yuichi Eto; Shigemi Okanishi
Original assignee: Idemitsu Engineering Co., Ltd.
Priority date: 1998-10-29
Filing date: 1999-10-26
Publication date: 2000-05-11
Also published as: TW565468B; KR20010085967A; JP3711327B2

Abstract

A method of recovering hydrocarbon vapor comprising a first step of cooling a gas containing hydrocarbon vapor by a first heat exchanger (11) to condense the same and removing part of the hydrocarbon vapor, a second step of heating the gas, which has part of its hydrocarbon vapor removed therefrom, by a second heat exchanger (14) to raise its temperature, and a third step of feeding the temperature-raised gas to adsorption towers (15, 16) filled with an adsorbent, where the hydrocarbon vapor is adsorbed for removal. Separation of the hydrocarbon from the adsorbent is effected by reducing the pressures in the adsorption towers (15, 16) while producing a counterflow of clean gas in the adsorption towers (15, 16).

Description

Description Method and apparatus for recovering hydrocarbon vapor

The present invention recovers hydrocarbon vapor contained in air and other gases discharged from the storage facility when liquid hydrocarbons such as gasoline are charged into storage facilities such as storage tanks and expansion due to temperature. And a device for performing the method. Background art

When filling liquid hydrocarbons such as gasoline, kerosene, and gas oil into purge, lorry, and storage tanks, the gas and air in the containers are replaced by gas and liquid phases in those containers. By expanding in response to changes in air temperature, gas containing hydrocarbon vapor (steam generated by volatilization of some components of liquid hydrocarbons) is discharged from the container. The concentration of hydrocarbon vapors in such exhaust reaches as much as 30% in summer.

Recently, regulations have been set for the emission of hydrocarbons. For example, prefectural regulations under the Pollution Control Ordinance, etc., set the concentration at 5-8% and the removal rate at 80-90%. Furthermore, stricter regulations are set for toxic pollutants. Conventionally, the following methods have been proposed for recovering hydrocarbon vapor in exhaust gas from storage tanks.

(1) After adsorbing hydrocarbon vapor using a removal device filled with activated carbon, separate the adsorbed hydrocarbon using heated steam. (2) Silica gel After adsorbing the hydrocarbon vapor using a removal device filled with Ruzelite, the hydrocarbon is separated by adsorption under reduced pressure, and (3) the membrane separation method.

On the other hand, in order to improve the recovery efficiency of the above-mentioned conventional method for recovering hydrocarbon vapor, the following invention has been proposed (JP-A-10-156127). In the present invention, in the recovery tower, the exhaust gas containing high-concentration benzene is brought into contact with pre-cooled heavy oil or benzene to partially remove the benzene vapor, and then the benzene vapor is removed in the adsorption tower filled with the adsorbent. Adsorption is removed. When separating benzene from the adsorbent, the pressure is reduced by a vacuum pump or the like while the adsorption tower is heated by a heating coil or the like through which steam flows inside. The separated benzene is returned to the above-mentioned recovery tower, where it is condensed and recovered.

According to the present invention, the benzene vapor is partially recovered and then adsorbed in the adsorption tower, so that benzene can be removed to near the limit and post-treatment of the separated benzene is easy.

However, when separating benzene from the adsorbent, the adsorption tower is heated by a heating coil or the like through which steam flows, but this indirect heating method is inefficient. In addition, since the adsorbent such as silica gel has low thermal conductivity and the granular materials are in point contact with each other, the heat transfer in the adsorbent packed bed is very slow. In adsorption (PTSA: Pressure & Temporature Swing Adsorption), the switching of adsorption and separation is performed in a matter of minutes, but in this time, the temperature rises substantially only to the surface of the heating coil and to a distance of several cm. I can't warm. Therefore, it is necessary to increase the number of heating coils, which requires extra space in the adsorption tower and uneven temperature in the adsorbent layer. The loss of steam for heating was increasing.

Disclosure of the invention

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

In the method for recovering hydrocarbon vapor of the present invention, a first step of cooling and condensing a gas containing hydrocarbon vapor by a cooling means, and removing a part of the hydrocarbon vapor, and a heating means A second step of heating and raising the temperature of the gas from which a part of the hydrocarbon vapor has been removed, and supplying the heated gas to an adsorption unit filled with an adsorbent; And a third step of adsorbing and removing the one.

The temperature of the gas after the treatment in the first step exceeds the freezing point of the contained components and is set to a low temperature near the freezing point of the parentheses.

The lower the temperature, the higher the amount of condensation and the lower the concentration of hydrocarbon vapor in the gas, so that the load on the subsequent stage is reduced and the size of the adsorption tower as the adsorption means is reduced. Because you can. For example, when benzene is the main component of hydrocarbon vapor, the freezing point of benzene is 5.5 ° C, so it is preferably 6 to 20 ° C, more preferably 6 to 10 ° C. .

Due to such a first step, for example, high-boiling impurities such as toluene, xylene, trimethylbenzene, coumarone, and indene contained in crude gas oil mainly composed of benzene generated by carbonization of coal, especially sublimation Naphthalene, which is a solid, is effectively removed by lowering the vapor pressure by cooling and dissolving in benzene. The temperature of the gas after heating in the second step is preferably 5 to 30 ° C. higher than the temperature after the treatment in the first step. More preferably, the temperature is higher by 10 to 20 ° C.

Such a temperature is set because the hydrocarbon vapor has reached the saturated state at the temperature at the time of cooling in the treatment of the first step. If the pressure drops further, condensation or solid precipitation occurs immediately. This phenomenon will cause clogging of pipes, malfunction of switching valves, and increase in pressure loss of adsorption towers.o

On the other hand, in the second step, the temperature of the gas after the first step can be raised, and the degree of saturation of the hydrocarbon vapor can be reduced to prevent condensation in pipes and the like. it can. Further, the temperature of the subsequent adsorption device can be raised to facilitate separation and regeneration after adsorption. Furthermore, the reduction in the concentration of hydrocarbon vapor reduces the load of the next third step, and makes it possible to reduce the size of the adsorption tower and vacuum pump.

On the other hand, in the next third step, the temperature of the adsorbent in the adsorption tower rises due to adsorption of hydrocarbon vapor, and falls due to separation. When the adsorption amount is several%, the temperature fluctuation is several ° C. Therefore, immediately after the operation of separating the hydrocarbon vapor from the adsorbent is completed, the gas containing the saturated concentration of the hydrocarbon vapor is discharged immediately after the operation of separating the hydrocarbon vapor from the adsorbent without performing the heating and temperature increasing operation according to the second step. If introduced, it may condense at the inlet of the adsorption tower or solid deposition may occur. Conversely, if the temperature of the gas to be introduced is too high, the adsorption capacity decreases, and the adsorption efficiency decreases. As the adsorbent to be filled in the adsorption means of the third step, silica gel, Ordinary adsorbents such as silica gel, alumina gel, and activated carbon can be used. From the viewpoint of safety, use of silica gel, zeolite, or alumina gel is preferred.

More preferably, it is silica gel treated with a high-temperature calcining or hydrophobizing agent or high silica zeolite having a silica / alumina ratio of 80 or more. If the adsorbent adsorbs water in the gas, it is necessary to separate water from the recovered oil, so it is difficult to adsorb water, but a hydrophobic adsorbent that adsorbs hydrocarbons is preferred. It is.

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

In such a third step, the adsorbent adsorbs and removes the hydrocarbon vapor, and discharges a clean gas. The adsorbent that has adsorbed the hydrocarbons in the third step is regenerated by separating the hydrocarbons by reducing the pressure. The degree of vacuum at the time of separation is preferably 60 Torr or less in absolute pressure. More preferably, the absolute pressure is 25 Torr or less. The lower the absolute pressure, the easier it is for hydrocarbon vapors to separate. If the separation of hydrocarbons is not sufficient, the adsorbent will be less likely to adsorb the hydrocarbon vapor in the next adsorption operation, and the efficiency of removing the hydrocarbon vapor will decrease. On the other hand, the hydrocarbon vapor separated from the adsorbent has a very high concentration and can be easily condensed by cooling and recovered as a liquid. As a cooling method, a general heat exchanger (tube type, plate type, etc.) can be used. In addition, the low-concentration hydrocarbon vapor that could not be condensed can be processed without being discharged out of the apparatus by mixing it with the raw material gas at the entrance of the apparatus. As another method of recovering hydrocarbon vapor, it can be recovered by contacting it with cooled light oil, kerosene, gasoline, recovered oil, etc. to cool and condense it, or dissolving it in these. The low-concentration hydrocarbon vapor that has not been condensed or dissolved may be mixed with the raw material gas at the entrance of the apparatus in the same manner as described above.

Further, the separated hydrocarbon vapor may be mixed with a gas containing the hydrocarbon vapor in the first step, and may be cooled and condensed to be recovered. The gas from which the hydrocarbon vapor is to be recovered may be ordinary air, or may be similar to nitrogen or other inert gas, etc., and may be a facility for the production or storage of liquefied hydrocarbons, which are sources of hydrocarbon vapor. It can be applied to various gases and the like discharged from such as appropriate. In the recovery method of the present invention, in the first step, the condensed liquid hydrocarbon is used, and the cooled liquid hydrocarbon is brought into contact with a gas containing a hydrocarbon vapor to form a hydrocarbon base in the gas. It is desirable to cool and condense the par.

In this case, since the condensed liquid hydrocarbon is used, efficient recovery can be achieved. 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 has been removed in the second step.

In other words, if steam is used as a heat medium, the temperature difference from the process gas is large, so if the flow rate of the process gas changes, heating failure or abnormal temperature rise may occur, which is not suitable. On the other hand, when hot water is used as the heating medium, there is no such problem. In addition, through the heat exchanger There is no problem in using hot water heated with steam.

In the recovery method of the present invention, in the third step, the temperature-raised gas from the second step is supplied to the adsorption means to adsorb the hydrocarbon vapor to the adsorbent, and then the pressure in the adsorption means is reduced. Then, it is desirable that a clean gas (normal air or an appropriate gas) be caused to flow back into the adsorption means, and that the hydrocarbons be separated from the adsorbent in this state.

In this way, when separating hydrocarbons from the adsorbent, the partial pressure of the hydrocarbon vapor is reduced by flowing back the clean gas from the outlet side of the adsorption tower to the inside, so that the hydrocarbons are adsorbed. It is easy to separate from the agent.

At this time, as the flow rate of the clean gas is increased, the separation of hydrocarbons is more likely to occur. However, if the flow rate is simply increased, the concentration of hydrocarbon vapor in the separated gas decreases and the Recovery by cooling and condensation in the process becomes difficult. Therefore, there is an optimum value for the flow rate of the clean gas, which is preferably 1/5 to 1/50, more preferably 1/10 to 50 times the flow rate of the process gas introduced into the adsorption tower during adsorption. 1/20.

In the recovery method of the present invention, a plurality of adsorption means are provided, and it is desirable that these adsorption means are alternately switched to an adsorption treatment and a separation treatment to perform a continuous treatment.

The switching of the adsorption means is preferably performed within one hour, more preferably within ten minutes. In order to reduce the temperature change of the adsorbent layer by reducing the change in the amount of adsorption of hydrocarbons, short-time switching is preferable.

In general, the heat of adsorption is an exotherm, while increasing the temperature makes adsorption more difficult (separation becomes more likely), and conversely, lowering the temperature causes adsorption. Easier (separation is less likely). Therefore, when the hydrocarbon vapor is adsorbed, the temperature of the adsorbent rises, and it becomes difficult to adsorb the hydrocarbon vapor further. Conversely, in the separation operation, when the hydrocarbon vapor separates, the temperature decreases, and further separation of the hydrocarbon vapor becomes difficult. That is, if the adsorption / separation operation is performed, a phenomenon occurs in which the effect of the operation is negated. Therefore, in order to reduce such an effect, it is effective to shorten the switching time between the adsorption process and the separation process. 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 in the first step, and then cooled and condensed to recover.

Since the separated hydrocarbons have a very high concentration and are easily condensed, they can be easily condensed and easily recovered by mixing them with the gas in the first step and treating them. This method is economically preferable since only one cooling condensing / recovering device is required. The apparatus for recovering a hydrocarbon vapor according to the present invention comprises: a cooling unit for cooling and condensing a gas containing the hydrocarbon vapor to remove a part of the hydrocarbon vapor; Heating means for heating and raising the temperature of the gas from which a part of the hydrocarbon vapor has been removed; and adsorbing means filled with an adsorbent for adsorbing and removing the hydrocarbon vapor in the heated gas. It is characterized by having.

The cooling means is appropriately selected from the following two in accordance with the concentration of the hydrocarbon vapor and the allowable pressure loss.

If the allowable pressure loss is high, a combination of a normal heat exchanger (tube type, plate type, etc.) and a gas-liquid separator is suitable. If the allowable pressure loss is low, a recovery tower with a built-in heat exchanger or a recovery tower with an external heat exchanger is suitable.

This recovery tower has a gas-liquid contact part at the top and a liquid reservoir at the bottom. The lower part is pumped out and introduced into the upper part for circulation.

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

The liquid level in the liquid reservoir is controlled by the balance between the pumping amount and the circulation amount.

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

As the heating means, an ordinary heat exchanger such as a tube type or a plate type can be used. In the recovery device of the present invention, it is preferable that a common chiller unit is provided as a supply source of the cooling heat medium supplied to the cooling unit and a supply source of the heating heat medium supplied to the heating unit. .

If a common chill unit is used, a single cooling medium and a heating medium can be supplied by one unit, which is economical and advantageous in space.

In addition, as the cooling unit and the heating unit, a refrigerator may be used. In the recovery apparatus of the present invention, it is preferable that a plurality of the adsorbing units are provided so as to alternately switch the adsorption process and the separation process to perform the continuous process. For example, one adsorption tower as the adsorption means may be a single tower, but it is preferable to provide a plurality of adsorption towers and perform the adsorption treatment continuously while switching the adsorption / separation operation. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of a hydrocarbon vapor recovery device according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a hydrocarbon vapor recovery device according to a second embodiment of the present invention.

FIG. 3 is a schematic view of a hydrocarbon vapor recovery device according to a comparative example. FIG. 4 is a schematic view showing a main part of a hydrocarbon vapor recovery apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic view showing a main part of a hydrocarbon vapor recovery device according to another embodiment of the present invention.

FIG. 6 is a schematic view showing a main part of a hydrocarbon vapor recovery device according to another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

With reference to FIG. 1, a method and an apparatus for recovering a hydrocarbon vapor according to a first embodiment of the present invention will be described.

The hydrocarbon vapor recovery device of the present embodiment includes a first heat exchanger 11 connected to an introduction line 10 for a gas (here, air) containing hydrocarbon vapor, and a gas supply to the heat exchanger 11. A gas-liquid separator 13 connected via a line 10A, a second heat exchanger connected to the gas-liquid separator 13 via a gas supply line 12, and a second heat exchanger 14 Gas supply line with two downstream branches The first and second adsorption towers 15 and 16 connected via the inlet 12A and the gas supply line 33A branched from the vicinity of the adsorption towers 15 and 16 of the gas supply line 12A are connected. The vacuum pump 20 is provided.

The first heat exchanger (tube type or plate type) 11 is provided with a refrigerator 17.

The gas-liquid separator 13 is provided with a liquid reservoir 19 at a lower portion thereof. At the gas outlet of the gas-liquid separator 13, a wire mesh type demister (not shown) is installed.

The second heat exchanger (tube type or plate type) 14 is provided with a heater 21. The heating medium of this heat exchanger is hot water.

Each of the first and second adsorption towers 15 and 16 has an adsorption layer 22 filled with an adsorbent therein.

Each gas supply line 12 from the second heat exchanger 14 to the first and second adsorption towers 15 and 16 is provided with first and second valves 23 and 24.

Third and fourth valves 25 and 26 are provided on a gas supply line 33A branched from the gas supply line 12A.

The first and second adsorption towers 15 and 16 are each connected at their top to a clean gas discharge line 31, and each line 31 is provided with fifth and sixth valves 27 and 28. I have.

A clean gas (here, clean air) flows back to the adsorption towers 15 and 16 through a line 31 between the fifth and sixth valves 27 and 28 and the tops of the adsorption towers 15 and 16. A supply line 32 for supplying clean air to be supplied is connected, and each line is provided with seventh and eighth valves 29 and 30.

A return line 33 for returning the separated hydrocarbon vapor is provided between the vacuum pump 20 and the introduction line 10 in front of the first heat exchanger 11. The procedure for recovering hydrocarbon vapor using this recovery device is as follows.

First, as a first step, air containing hydrocarbon vapor is passed through the first heat exchanger 11 from the introduction line 10, where the air is cooled to condense the hydrocarbon vapor, The cooled and condensed hydrocarbons and air are supplied to a gas-liquid separator 13 for gas-liquid separation. Part of the condensed hydrocarbon vapor is collected in the liquid reservoir 19 and collected. On the other hand, the air containing the remaining hydrocarbon vapor is supplied to the second heat exchanger 14 from the outlet.

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

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

These first and second adsorption towers 15 and 16 switch the valves 23, 24, 27 and 28 alternately to the adsorption treatment and the separation treatment to continuously process the hydrocarbon vapor.

During the separation process, the pressure inside the adsorption towers 15 and 16 is reduced by the vacuum pump 20, and the clean air is flowed back into the adsorption towers 15 and 16 from the clean air supply line 32 to adsorb hydrocarbons in this state. Separate from agent.

The separated hydrocarbons are returned to the inlet side of the heat exchanger 11, mixed with air containing hydrocarbon vapor, and collected by cooling and condensing by repeating the above-mentioned first and subsequent steps. . (Second embodiment)

Referring to FIG. 2, recovery of hydrocarbon vapor according to the second embodiment of the present invention The method and the apparatus will be described.

The hydrocarbon vapor recovery device of the present embodiment includes a recovery tower 36 connected to an introduction line 10 for a gas (here, air) containing hydrocarbon vapor, and a liquid between a lower part and an upper part of the recovery tower 36. A first heat exchanger 11 provided via a hydrocarbon circulation line 39 of the first type, a second heat exchanger 14 connected to the recovery tower 36 via a gas supply line 12, and First and second adsorption towers 15 and 16 connected to the second heat exchanger 14 via a gas supply line 12A whose downstream side is branched into two, and adsorption towers 15 and 16 of these gas supply lines 12A. It is provided with a vacuum pump 20 connected via a gas supply line 33A branched from a portion near 16.

The recovery tower 36 is provided with a gas-liquid contact part 37 at the upper part and a liquid reservoir part 38 at the lower part. The gas-liquid contact part 37 is filled with a filler such as a Raschig ring. At the gas outlet of the recovery tower 36, a wire mesh type demister (not shown) is installed.

One of the liquid hydrocarbon circulation lines 39 is connected to the liquid reservoir 38 side of the recovery tower 36, and the other is inserted above the gas-liquid contact part 37 in the recovery tower 36, and is connected to the end. A liquid hydrocarbon sprayer 41 is provided. A circulation pump 42 is provided between the liquid reservoir 38 of the circulation line 39 and the first heat exchanger 11. Other components of the apparatus, for example, the first heat exchanger 11, the second heat exchanger 14, the first and second adsorption towers 15, 16 and the vacuum pump 20, etc. This is the same as the embodiment. The procedure for recovering hydrocarbon vapor using this recovery device is as follows.

First, as a first step, air containing hydrocarbon vapor is supplied from the introduction line 10 to the recovery tower 36, where the air is cooled to form hydrocarbon vapor. The liquid is condensed and the generated liquid is stored in the liquid reservoir 38. When the air is cooled and condensed, the liquid hydrocarbons in the liquid storage section 38 are partially circulated through the circulation line 39 and are cooled in the first heat exchanger 11, and then are collected in the recovery tower 36. The liquid hydrocarbon and the air are brought into contact with each other at a gas-liquid contact section 37 to perform the supply.

Subsequent second and third steps are the same as in the first embodiment described above. In the first and second embodiments, the first heat exchanger 11 is provided with the refrigerator 17 and the second heat exchanger 14 is provided with the heater 21. However, the first heat exchanger 1 A common chiller unit may be provided as a supply source of the cooling heat medium supplied to 1 and a supply source of the heating heat medium supplied to the second heat exchanger 14.

Further, the recovery tower 36 may be configured as follows. As shown in FIG. 4, the recovery tower 36 is provided with a gas-liquid disperser 37A such as a chimney tray perforated tray between the gas-liquid contact part 37 and the introduction part of the circulation line 39. A demister 37B is installed above the 39 introduction part. The liquid reservoir 38 is connected to an extraction line 42A extending from the side of the recovery tower 36 to the circulation pump 42, the suction end of which is directed downward, and is arranged radially around it. A vortex breaker 42B made of multiple plates is also installed.

By installing the gas-liquid disperser 37A, further contact between the liquid-phase component returned from the circulation line 39 and the gas-phase component rising through the gas-liquid contact part 37 is achieved. Recovery of liquid phase components can be promoted. In addition, the installation of the demist 37B makes it possible to remove mist-like liquid phase components from the gas taken out to the gas supply line 12 at the top of the tower. Further, by installing the vortex breaker 42B, the liquid accumulated in the liquid reservoir 38 from the extraction line 42A is sucked. The occurrence of swirls and gas entrainment on exit is avoided.

As a specific structure of the gas-liquid disperser 37A, the demising device 37B, and the vortex breaker 42B, a structure used in the existing brand technology may be appropriately adopted. As shown in FIG. 5, a substantially U-shaped recovery tower 36A may be employed. In the figure, an introduction line 10 is connected to one of the tops (left side in the figure) of a substantially U-shaped recovery tower 36A, and a circulation line 39 is connected slightly below the top. A gas-liquid disperser 37A is installed slightly below the connection part of the circulation line 39, and a gas-liquid contact part 37 is installed below it. The gas supply line 12 is connected to one of the tower tops (right side in the figure), and a demister 37B is installed below it. Although the lower part of the recovery tower 36A is wider, it has the same structure as that of Fig. 4 described above. Such a substantially U-shaped recovery tower 36A also separates the hydrocarbon vapor contained in the gas from the introduction line 10 and the circulation line 39, and supplies the separated gas to the gas supply line. It can be taken out from the line 12 and stored in the liquid reservoir 38. Although each of the embodiments described above treats a hydrocarbon-containing gas from a single inlet line 10, it may treat hydrocarbon-containing gas from multiple gas sources. In such a case, it is desirable to supplement the structure to avoid mixed contamination (contamination) due to backflow between the gas sources.

In Fig. 6, two introduction lines 10L and 10H are connected to the recovery tower 36A. The introduction line 10L is connected to the top of the tower in the same way as the introduction line 10 in Fig. 5. The introduction line 10H is connected between the gas-liquid contact part 37 of the recovery tower 36A and the gas-liquid disperser 37A. Here, the gas source supplied to the introduction line 10H has a higher concentration or purity of the stored liquid 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 ink, and the guide line 10H is connected to the exhaust port of the pure benzene ink.

In such a case, if the introduction line 10H is simply connected to the recovery tower 36A, the low-purity benzene component from the introduction line 10L is introduced into the recovery tower 36A. Ingredients flow back into the pure benzene tank through the introduction line 10H, which can cause a decrease in benzene purity in the tank.

Therefore, a seal pot 10P is installed in the introduction part of the introduction line 10H, and the content liquid (here pure benzene) of the gas source connected via the introduction line 10H is stored in this. Then, the end of the introduction line 10H is immersed in the liquid phase in the seal pot 10P.

This can prevent backflow from the introduction line 10H. The plurality of gas sources are not limited to the same type, but may be different types such as gasoline and benzene as long as the collection targets overlap. Hereinafter, specific experimental examples performed based on each of the above-described embodiments will be described.

(Experimental example 1)

In the first embodiment, specific examples of the method and the apparatus are as follows.

The flow rate of air containing high-concentration hydrocarbon vapor to be treated (hereinafter referred to as “source gas”) was 10 m3, and the concentration of hydrocarbon vapor was 20 vol%. The components of the hydrocarbon vapor in this air were as shown in Table 1 below. (table 1 )

First, the raw material gas and the separation gas from the outlet of the vacuum pump 20 are combined, cooled in the first tube-type heat exchanger 11 and partially condensed, and then condensed into the vertical gas-liquid separator 13. And separated into gaseous and liquid phases.

The temperature of the gas after being cooled in the first heat exchanger 11 was 10 ° C. The amount of the collected liquid hydrocarbon was 3.9 kg / hr.

Next, the gas discharged from the gas-liquid separator 13 was introduced into a second tubular heat exchanger 14, where the temperature was increased. The temperature of the gas after heating in this heat exchanger 14 was 30 ° C.

Subsequently, the heated gas was supplied to one of the two adsorption towers 15 where the hydrocarbon vapor was adsorbed and removed by an adsorbent. The adsorbent used was a silica gel [Sili Gel CARiACT Q-3 (trade name) manufactured by Fuji Silicia Chemical Co., Ltd.] that had been subjected to hydrophobic treatment by baking at 500 ° C for 4 hours. The two adsorption towers 15, 16 switched the inlet and outlet valves 23, 24, 27, 28 every 5 minutes to alternately perform adsorption and separation.

The concentration of hydrocarbon vapor in the gas of the adsorption tower 15, 16 exit _c also was 30ppm, the components of the hydrocarbon base one par are as shown in Table 2 below.

(Table 2)

The operation of separating hydrocarbons from the adsorbent in the adsorption towers 15 and 16 is performed by This was performed by reducing the pressure with a vacuum pump 20. The separation pressure at this time is 25 Torr in absolute pressure. This separation is carried out by flowing back clean air at a flow rate of lm3 / hr from the outlets of the adsorption towers 15, 16 through the clean air supply line 32.

The separation gas from the outlet of the vacuum pump 20 was combined with the raw material gas in the introduction line 10 and collected by cooling and condensing in the first heat exchanger 11.

The temperature of the adsorbent during adsorption / separation was measured with a thermocouple inserted into the adsorption towers 15 and 16, and the maximum was 35 ° C during adsorption and minimum 25 ° C during separation.

During the operation, the pressure loss of the adsorption towers 15 and 16 was almost constant at 20 mmH20.After the operation was completed, the pipes of the adsorption towers 15 and 16 were inspected for opening, but abnormalities such as condensation of hydrocarbon vapor were observed. I couldn't see it.

(Experimental example 2)

In the second embodiment, specific examples of the method and the apparatus are as follows.

The air containing high-concentration hydrocarbon vapor to be treated is the same as in Experimental 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 vertical recovery tower 36. The liquid in the liquid reservoir 19 of the recovery tower 36 is withdrawn by the pump 42, cooled in the first tubular heat exchanger 11, and then introduced into the upper part of the recovery tower 36, where it is brought into contact with the raw material gas and The hydrocarbon vapor inside was condensed. The temperature of the gas after cooling in the heat exchanger 11 was 10 ° C.

Here, the gas phase and the liquid phase after the gas-liquid contact were separated, and the gas phase was withdrawn from the upper part of the recovery tower 36, and the liquid phase was recovered in the lower liquid storage part 38. The amount of liquid hydrocarbon collected was 3.9 kg / hr.

Next, the gas discharged from the recovery tower 36 is introduced into the second plate-type heat exchanger 14. Then, the temperature was increased by heating. The temperature of the gas after heating in the heat exchanger 14 was 25 ° C.

Next, the heated gas was supplied to one of the two adsorption towers 15, where the hydrocarbon vapor was adsorbed and removed by an adsorbent. The adsorbent used was silica gel [Silica gel CARiACT (3-6 (trade name), manufactured by Fuji Silysia Chemical Ltd.)], which was subjected to a hydrophobizing treatment by baking at 500 ° C for 4 hours. In towers 15 and 16, inlet and outlet valves 23, 24, 27, and 28 were switched every 5 minutes to alternately perform adsorption and separation.

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

(Table 3)

The operation of separating hydrocarbons from the adsorbent in the adsorption towers 15 and 16 was performed by reducing the pressure in the adsorption towers 15 and 16 with the vacuum pump 20. The separation pressure at this time is 20 Torr in absolute pressure. This separation is performed while the clean air flows back through the clean air supply line 32 from the outlets of the adsorption towers 15 and 16 at a flow rate of 0.5 m3 / hr.

The separation gas from the outlet of the vacuum pump 20 was combined with the raw material gas on the introduction line 10 and was cooled and condensed in the recovery tower 36 and recovered.

The temperature of the adsorbent during adsorption / separation was measured with a thermocouple inserted into the adsorption towers 15 and 16, and was found to be a maximum of 30 ° C during adsorption and a minimum of 20 ° C during separation.

During the operation, the pressure loss of the adsorption towers 15 and 16 was almost constant at 20 mmH20.After the operation was completed, the pipes of the adsorption towers 15 and 16 were inspected for opening, but abnormalities such as condensation of hydrocarbon vapor were observed. I couldn't see it. (Comparative Example 1)

As shown in FIG. 3, the apparatus according to the present comparative example has a configuration in which the second heat exchanger 14 is removed from the apparatus according to the second embodiment, and the adsorption towers 15 and 16 have heating coils 45 through which steam flows. Machine 46 is provided.

The air containing 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 vertical recovery tower 36. The liquid in the liquid storage section 38 of the recovery tower 36 is withdrawn by the pump 42, cooled in the first tube-shaped 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 inside was condensed. The temperature of the gas after cooling in the heat exchanger 11 was 10 ° C.

Next, the gas discharged from the recovery tower 36 was directly supplied to one of the two adsorption towers 15, where the hydrocarbon vapor was adsorbed and removed by the adsorbent. The adsorbent used was silica gel [silica gel CA RiACT Q-6 (trade name) manufactured by Fuji Silica Chemical Co., Ltd.], which was subjected to hydrophobizing treatment by baking at 500 ° C for 4 hours. In the two adsorption towers 15 and 16, adsorption and separation were alternately performed by switching the inlet and outlet valves 23, 24, 27 and 28 every 5 minutes.

The concentration of hydrocarbon vapor in the gas from the adsorption towers 15 and 16 was 100 to 200111, and a tendency to increase gradually was observed. The components of the hydrocarbon vapor for the first week were as shown in Table 4 below. (Table 4)

The operation of separating hydrocarbons from the adsorbent in the adsorption towers 15 and 16 was performed by reducing the pressure in the adsorption towers 15 and 16 with the vacuum pump 20. The separation pressure at this time is 20 Torr in absolute pressure. This separation was performed while backflowing clean air from the outlets of the adsorption towers 15 and 16 at a flow rate of 0.5 m3 / hr.

The separation gas from the outlet of the vacuum pump 20 was combined with the raw material gas at the entrance of the apparatus, and was cooled and condensed in the recovery tower 36 and recovered.

When the temperature of the adsorbent during adsorption and separation was measured with a thermocouple, the maximum was 15 ° C during adsorption, the minimum at 10 ° C during separation, and the maximum at 40 ° C, and rose in the adsorption towers 15 and 16. There were many times.

During one week of operation, the pressure loss of the adsorption towers 15 and 16 tended to increase gradually at 20 to 30 mmH20.

After the operation was completed, an open inspection of the adsorption towers 15 and 16 and the piping was carried out. Condensation of hydrocarbon vapor was observed in the lower part of the adsorption towers 15 and 16 and near the valve in the middle of the pipes. Industrial applicability

It can be used to prevent diffusion and recovery and reuse of hydrocarbon vapor discharged from storage tanks, etc. in storage facilities for liquid hydrocarbons such as gasoline or processing facilities for refining.

Claims

The scope of the claims

1. A first step of cooling and condensing a gas containing hydrocarbon vapor by a cooling means to remove a part of the hydrocarbon vapor, and removing a part of the hydrocarbon vapor by a heating means A second step of heating the heated gas to raise the temperature,

Supplying the heated gas to an adsorption means filled with an adsorbent, wherein a third step of adsorbing and removing the hydrocarbon vapor is performed;

A method for recovering hydrocarbon vapor.

2. The method for recovering hydrocarbon vapor according to claim 1, wherein in the first step, the condensed liquid hydrocarbon is used, and the cooled liquid hydrocarbon is contacted with a gas containing hydrocarbon vapor. A method for recovering hydrocarbon vapor by cooling and condensing hydrocarbon vapor in the gas.

3. The method for recovering hydrocarbon vapor according to claim 1, wherein in the second step, hot water is used as a heat medium for heating the gas from which a part of the hydrocarbon vapor has been removed. How to recover hydrogen vapor.

4. In the method for recovering hydrocarbon vapor according to claim 1,

In the third step, the heated gas from the second step is supplied to the adsorbing means to adsorb the hydrocarbon vapor onto the adsorbent, and then the pressure in the adsorbing means is reduced to clean the inside of the adsorbing means. A method for recovering hydrocarbon vapor, characterized in that a natural gas is caused to flow backward and hydrocarbons are separated from the adsorbent in this state.

5. The method for recovering hydrocarbon vapor according to claim 4,

In a third step, a plurality of adsorbing means are used, and the adsorbing means is alternately switched to an adsorbing treatment and a separating treatment to carry out a continuous treatment. —How to collect pars.

6. The method for recovering hydrocarbon vapor according to claim 4, wherein the hydrocarbon separated from the adsorbent in the third step is mixed with a gas containing a hydrocarbon vapor in the first step, and cooled and condensed. A method for recovering hydrocarbon vapor, characterized in that it is recovered by recovery.

7. Cooling means for cooling and condensing a gas containing hydrocarbon vapor, and removing a part of the hydrocarbon vapor.

Heating means for heating and raising the temperature of the gas from which a part of the hydrocarbon vapor has been removed;

Adsorbing means filled with an adsorbent for adsorbing and removing hydrocarbon vapor in the heated gas;

An apparatus for recovering hydrocarbon vapor, comprising:

8. The hydrocarbon vapor recovery device according to claim 7,

A common chiller unit is provided as a supply source of a cooling heat medium to be supplied to the cooling means and a supply source of a heating heat medium to be supplied to the heating means. Collection device.

9. The hydrocarbon vapor recovery device according to claim 7,

A hydrocarbon vapor collecting apparatus, wherein a plurality of the adsorbing means are provided for performing a continuous treatment by alternately switching an adsorption treatment and a separation treatment.