KR19990081068A - Adsorption Collection and Adsorption Recovery System for Volatile Petroleum Compounds - Google Patents

Abstract

Hydrocarbons are adsorbed and removed by supplying polluted air with a total volume ratio of about 15% to 53% of hydrocarbons from volatile petroleum compounds refining, storage and handling facilities to an adsorption trap filled with silica gel and activated carbon. By discharging only clean air that satisfies the allowable value of 0.15-10g / m ³ to the atmosphere, air pollution is prevented, and hydrocarbons obtained by regenerating hydrocarbons adsorbed on the adsorption collection tower are treated with two-stage adsorption recovery system. Adsorption collection device of volatile petroleum compound and two tower absorption recovery device which can prevent the loss of resources by coagulation recovery and its operation method.

Description

Adsorption type collection device, adsorption recovery device and operation method of volatile petroleum

Petroleum refining facilities, petrochemical manufacturing facilities, storage and shipping facilities, and storage facilities for hydrocarbons that discharge petrochemical products and organic materials with a vapor vapor pressure of 10.3 kPa (or 1.5 psia, 1 kPa = 0.0102 kg / cm ² ) or higher among hydrocarbons In addition, volatile petroleum compounds emitted from shipping facilities and storage facilities at gas stations cause air pollution and resource loss. In the United States and the European Union, laws that regulate the amount of hydrocarbons volatilized to the atmosphere when handling 1,000 liters of gasoline, which is highly volatile among petroleum compounds, are less than 10g and in Germany less than 0.15g (excluding methane). It is in the stage of implementation.

In general, air contaminated with gasoline vapor is mainly composed of fatty hydrocarbons and consists of some aromatic compounds and naphthenes. Typical volume concentrations of aliphatic hydrocarbons in gasoline contaminated air are methane 0.05%, ethane 0.1%, propane 0.62%, butanes 11.1 -18.6%, pentanes 8.1-14.5%, hexanes 2.6-3.0%, and haptans above 0.19 0.9% and the rest is air. Hydrocarbon concentrations in contaminated air vary with season and type of gasoline, but the volume fraction of total hydrocarbons is about 20-40%. Approximately 1.75 liters of liquid gasoline at a volume concentration of hydrocarbons in the gasoline contaminated air lost by volatilization when handling 1000 liters of gasoline and an average molecular weight and density of 68.5 g / mol and 0.7 g / cm ³ , respectively. This loss is equivalent to 0.175% of gasoline handling. In addition, when handling 1000 liters of gasoline, the recovery rate of the recovery facilities that satisfy the conditions regulating the total amount of hydrocarbons discharged to the atmosphere of 0.15-10 g should be 99.18-99.98%. Recovery techniques for recovering and recycling resources while recovering volatile petroleum compounds volatilized into the atmosphere include a membrane separator, a deep cold separator, an absorber, an adsorption unit, and a mixed separator combining them. However, as emission limits become more stringent, a recovery process using either an adsorptive separator or a mixture of other separators should be used.

Membrane Separation Recovery Device is a membrane separation device developed for recovering vinyl chloride monomer from PVC manufacturing process or dichloromethane from chemical plant. Ethylene, propylene, butene, etc. Olefins are being applied to recover hydrogen from off-gas from refineries (K. Ohlrogge et al., Industrial Applications to Separate Volatile Organic Compounds from Industrial Off-gas Stream, AIChE Spring National Meeting, March 9-13, 1997) . In order to recover gasoline components by membrane separation, a multistage system must be constructed and a large pressure difference must be maintained between the membranes. Adsorption technology is mainly operated by accumulating, adsorption removal and desorption processes continuously with a plurality of adsorption towers filled with activated carbon, silica gel, zeolite, etc., and used to recover hydrocarbons by treating contaminated air of volatile petroleum compounds. For example, the adsorption process for recovering hydrocarbons from polluted air discharged from refineries and low oil stations, etc. can be regenerated by depressurization, low pressure washing and desorption (Japan 7-284623, Japan 9-141039), adsorption towers. It is regenerated by using a sealed vacuum pump under reduced pressure and low pressure cleaning. In order to prevent the volatile organic compound component that is desorbed from being absorbed by the vacuum pump oil, the pump oil may be heated to a dew point (US Patent 4,857,084). A recovery system that collects polluted air from the handling facilities of volatile petroleum compounds in a storage tank and combines it with absorption, membrane separation and adsorptive separation (Hydrocarbon Process ssing, Aug. 1996).

The present invention is an adsorptive collection device capable of efficiently collecting volatile petroleum compounds that are discharged from the refining, storage and handling facilities of volatile petroleum compounds causing air pollution and resource loss, and an adsorptive collection device adsorbing hydrocarbons. The mixture of volatile petroleum compounds and air obtained by desorption at a pressure lower than atmospheric pressure by a low pressure cleaning method is treated with a two- tower adsorption and recovery system to recover and recycle hydrocarbons in the liquid phase and to collect volatile petroleum compounds that can prevent air pollution. The present invention relates to a device, a recovery device, and a method of operating the same.

① In the refining, storage and handling facilities of volatile petroleum compounds, a large amount of polluted air is sporadically released into the atmosphere in a short time while refueling petroleum. Until now, the polluted air is collected in a fluid storage tank whose level (water level) changes according to the amount of polluted air, and then the collected polluted air is supplied to a recovery facility to recover hydrocarbon components and discharge clean air to the atmosphere. However, when collecting polluted air at high flow rates and sporadic discharges in a short time using a liquid storage tank, the storage tank must be large. Therefore, by devising a device that can efficiently collect the polluted air, the size of the recovery device should be greatly reduced.

② The polluted air of volatile petroleum compounds is composed mainly of aliphatic hydrocarbons and composed of aromatic compounds and naphthenes. The volume ratio of total hydrocarbons is about 20-40%, and the rest is air. In the case of adsorptive separation of hydrocarbon components and air, it should be possible to continuously use the adsorbent and enjoy the energy amount for recovery. In the adsorptive separation technique, zeolite or activated carbon is generally used as the adsorbent. The adsorption propensity of pentane and hexane anomalies to these adsorbents is a convex adsorption isotherm with a large adsorption amount even at low partial pressure, so that the adsorption column is heated and regenerated or the pressure of the adsorption tower is maintained at a pressure lower than atmospheric pressure to desorb the hydrocarbon. However, if these hydrocarbon components cannot be reversibly desorbed during the continuous operation, they accumulate gradually in the adsorbent, so that the adsorbent cannot be used for a long time and needs to be replaced frequently. Therefore, by using an adsorbent having a linear adsorption isotherm for hydrocarbons having relatively high boiling points, such as pentane and hexane abnormalities, it should be able to be reversibly regenerated by only decompression and low pressure washing.

③ An object of the present invention is to supply the polluting air of volatile petroleum compounds which is volatilized in the facility storing or handling volatile petroleum compounds to the collection column filled with silica gel and activated charcoal, which causes air pollution and resource loss. It is to devise an adsorption collection device that can discharge clean air to the atmosphere while satisfying the emission allowance of 0.15-10g / m ³ ,

④ Another object of the present invention is to use a combination of silica gel and activated carbon to remove a portion of pentanes, hydrocarbon components of more than hexanes in the silica gel layer, methane, ethane, propane, butanes and a portion of pentane as the activated carbon layer By removing, devising an adsorption tower capable of almost reversibly regenerating the adsorption tower with reduced pressure and low pressure cleaning,

⑤ Another object of the present invention is to desorb the collection tower to which hydrocarbon components are adsorbed under reduced pressure and low pressure at a pressure lower than atmospheric pressure, thereby treating the mixture of volatile petroleum compound and air obtained by using two-stage adsorption recovery system. The present invention is to devise an adsorption recovery apparatus for volatile organic compounds and a method of operating the same, which can be recovered and recycled in the liquid phase to prevent air pollution and resource loss.

1 is an adsorption trap and adsorption recovery device of a volatile petroleum compound

2 is a continuous operation diagram of the adsorption recovery device for volatile petroleum compounds

Figure 3 is a flow rate of polluted air, low pressure cleaning gas and clean air treated in the adsorption recovery device

4 is a contaminated air composition of the volatile petroleum compound treated in the adsorption recovery device of the volatile petroleum compound

5 is the performance of the adsorption recovery device for volatile petroleum compounds

The apparatus shown in FIG. 1 is used to capture the polluted air discharged from oil refineries that produce petroleum, oil and gas stations that store and handle petroleum, and storage and handling facilities of factories that use petroleum. 1 packed adsorption collection tower, 2 adsorption towers filled with silica gel and activated carbon for treating contaminated air obtained by regeneration of adsorption collection tower, 1 heat exchanger and 2 storage tanks for condensing and recovering the high concentration hydrocarbon obtained by regeneration of adsorption tower. Consists of two sealed, sealed or DRY vacuum pumps.

① Operation of adsorption type collecting tower

When filling oil into storage tanks at storage stations or refineries, or when filling tank lorry carrying oil from storage tanks, and filling tanks with oil in storage tanks in a short time and irregularly Air contaminated with the volatile petroleum compound is supplied to the adsorption type collecting tower 11 through the passage 30. In this process, some of the pentane, hexane, and haptan hydrocarbons having high adsorption in the petroleum compound are adsorbed and removed from the silica gel layer, and some of the less adsorbable methane, ethane, propane, butane and pentane are adsorbed and removed from the activated carbon layer. , the discharge limit of O.15 - and discharges clean air only satisfying 1Og / m ³ to the atmosphere through the passage 32 and the valve 31. When collecting volatile petroleum compounds, a thermocouple is installed at the 11/12 point of the adsorption collection tower. When the temperature change is about 15-50 ° C, the collection process is stopped and the adsorption collection tower 11 is desorbed. The adsorption collection tower 11 operates the vacuum pump 16 to maintain a final pressure of 30-100 mmHg, while the adsorption collection tower 11 receives clean gas containing no hydrocarbons contained in the reservoir 15 via the flow path 33. It is supplied to to desorb the hydrocarbon component. At this time, the low pressure clean gas used for regeneration of the activated carbon layer is supplied through the flow path 34, and the low pressure clean gas used for the regeneration of the silica gel layer is supplied through the flow path 35 to increase the desorption efficiency of the hydrocarbon component.

② Operation of two tower type suction recovery device

The circumferential operation of the two- tower adsorption recovery device undergoes a process of accumulating, adsorption, decompression, and depressurization washing (FIG. 2). In the pressure storing process, when the adsorption collection tower 11 is regenerated, a gas containing a mixture of the high concentration hydrocarbons obtained through the passage 36 and the uncondensed gas discharged through the passage 37 from the top of the condensation heat exchanger 14 is flowed through the passage 38 and the valve 1a. The pressure of the tower is increased from the initial 30-100 mmHg to the adsorption pressure of 800-100 mmHg by supplying the adsorption tower 12 through the " The adsorption process is carried out through the adsorption tower through the flow path 38 and the valve (1a) through a mixture of the high concentration hydrocarbons and the uncondensed gas discharged through the flow path 37 at the top of the condensation heat exchanger (14). It supplies to (12). At this time, some of the hydrocarbon components of pentane, hexane, and haptan or more are adsorbed and removed on the silica gel layer, and some of the adsorptive methane, ethane, propane, butanes and pentane are adsorbed and removed on the activated carbon layer. The clean gas containing no hydrocarbon is sent to the storage tank 15 through the flow passage 39 and the valve 3a, and used for the desorption of the adsorption type collecting tower 11. While the adsorption tower 12 undergoes a pressure storing and adsorption process, the adsorption tower 13 undergoes a desorption process by decompression and low pressure washing. The pressure was reduced by opening the valve 2b and operating the vacuum pump 17 to reduce the pressure of the adsorption column to 100-200 mmHg, thereby desorbing the silica gel and the hydrocarbon component adsorbed on the activated carbon. The low pressure cleaning supplies a portion of the clean gas discharged through the valve 3a when the adsorption tower 12 passes through the valve 3a to the activated carbon layer of the adsorption tower 13 through the channel 40 and the valve 4b. 41 and the valve (4d) is supplied to the silica gel layer to increase the desorption efficiency of the hydrocarbon component by using a partial pressure difference at a vacuum pressure of 30-100 mmHg. The mixture of the high concentration hydrocarbon component and the clean gas desorbed through the vacuum pump 17 is supplied to the condensation heat exchanger 14 through the flow path 42. Hydrocarbons condensed and recovered by cooling water (Euro 44) with a temperature of 5-25 ° C are recycled to the storage tank via Euro 43, and uncondensed gas is contaminated air obtained by desorbing the adsorption trap (11). ) And feed it to the 2 tower adsorption recovery device. The operating pressure of the condensation heat exchanger is 1200-1800 mmHg.

Hereinafter, the present invention specified in FIG. 1 will be described in detail with reference to Examples.

Example

The adsorptive collection device and recovery device of the volatile petroleum compound described in FIG. 1 were applied to the contaminated air of the volatile petroleum compound to obtain the following results. The contaminated air 9 was treated with a volumetric ratio of 15-53% of volatile petroleum compounds using an adsorption recovery system consisting of two adsorption towers of 2100 cm ^{3 and} a volume of 0.85 kg and 0.42 kg of silica gel and activated carbon, respectively (Fig. 3). When the polluted air is supplied to the adsorption recovery tower at a flow rate of 11-18 Nl / min, hydrocarbons are adsorbed and removed, and the gas chromatograph (FID: Flame Ionization Detector detector) analyzes the gas discharged from the tower outlet during adsorption. Only clean air without detected hydrocarbons could be vented at 4-12 Nl / min. The adsorption recovery tower was desorbed by supplying low pressure clean air at about 1.2-4 Nl / min in the opposite direction to which polluted air was supplied during the adsorption process while maintaining the adsorption tower pressure at 30-100 mmHg. Figure 4 shows the change of the polluted air flow rate of the volatile organic compounds treated during the continuous operation of a total of 1740 cycles, the clean air flow rate discharged from the recovery device and the low pressure cleaning gas flow rate supplied to the desorption process of the adsorption tower.

As a representative example of the results, when the contaminated air having a volume ratio of hydrocarbons of about 21 to 27% was supplied to the recovery apparatus of FIG. 1 with an average flow rate of 11 Nl / min, the hydrocarbons recovered by condensation during about 8 cycles of operation or 2 hours It was about 1150 ml (FIG. 5).

6 shows the temperature change measured at each point of the silica gel layer and the activated carbon layer in the 200th cycle and the 1673th cycle during the continuous operation of the adsorption recovery apparatus. During continuous operation of the adsorption and recovery system, the adsorption period was 4-8 minutes, which corresponds to the point where the temperature change range of 5/6 points of activated carbon layer is 15-50 ° C. The function of the activated carbon layer was to remove sub-butanes and some components of pentane. As these hydrocarbons are adsorbed, the temperatures of the adsorption towers increase 7/12, 9/12, 11/12. The rapid rise in temperature at 11/12 is due to the adsorption of hydrocarbon components below butanes. At this point, if the temperature change between desorption and adsorption is 15-50 ° C, the operating method is adjusted to proceed directly to desorption. It became.

Atmospheric environmental pollution by removing the hydrocarbons from the polluted air discharged from the storage or handling facilities of the volatile petroleum compound using only the adsorptive collection device and recovery device of the volatile petroleum compound devised in the present invention Can be prevented. Scattered and irregularly discharged polluted air can be greatly reduced by using an adsorption type collecting tower. Also, as a result of using an adsorption tower filled with silica gel and activated carbon, some of the pentanes and hydrocarbons of hexane or higher in the silica gel layer By removing some of the pentanes and hydrocarbons below butanes from the activated carbon layer, the adsorption tower was reversibly regenerated using only the reduced pressure and low pressure washing methods without using the heat regeneration method. When handling volatile petroleum compounds in oil refineries, oil reservoirs, and gas stations, it was possible to provide a device and an operation method for preventing the loss of resources and air pollution by collecting and recovering hydrocarbons emitted to the atmosphere.

Claims (2)

Hayeoseo hydrocarbon volume ratio is discharged from the refinery and storage facilities and the handling facility of the volatile oil supply compound for about 15-53% of the contaminated air in the suction collection container (11) common discharge limit of 0.15 satisfying 10g / m ³ The clean air is discharged to the atmosphere through the flow path 32 and the valve 31, and the adsorption collection tower (1 l) is passed through the flow 34 and the flow path 35 through the flow 34 of the clean gas in the reservoir 15 while maintaining the suction collection tower 11 at a pressure of 30-10 mmHg. Gas (Euro 36) and the gas (Euro 37) discharged from the upper end of the condensation heat exchanger 14 are mixed and supplied to the adsorption tower (12) (13) through the valve (1a) (1b) Thus, hydrocarbons are removed and only the clean gas is sent to the storage tank 15 through the valves 3a and 3b, and the clean gas is discharged to the valve 4a and 4b while maintaining the pressure of the adsorption tower 12 and 13 at 30-100 mmHg. The mixture obtained by feeding through 4c and 4d is passed through a vacuum pump (l7) and a flow path (42). It is connected to the lower end of the heat exchanger (14), the heat exchanger for condensation 14 is heat exchanged with the cooling water supplied to the flow path 44 is characterized in that the hydrocarbon is condensed and recycled to the storage tank via the flow path 43 Adsorption type collecting device and adsorption recovery device of volatile petroleum compound of (1). The method of claim 1, Adsorption towers (11) and (12) filled with silica gel to remove a portion of pentane and hexane from aliphatic hydrocarbons contained in contaminated air of a volatile petroleum compound and activated carbon to remove a portion of pentane and a portion of butane are removed. Part of the two- tower volatile petroleum compound recovery device of Figure 1, characterized in that by using two to remove hydrocarbons from the polluted air.