DE2355288A1 - Storage tank organic vapour emission reduction system - simultaneously cools and condenses vapour using cooled fluid - Google Patents

Abstract

The emission is reduced by cooling and condensation of the mixture of air, gas and vapours expelled from the tank on filling. Cooling and condensation take place simultaneously in a virtually isobar section from an initial temperature down to a lower one and in an isobar-isothermal section connected to it giving virtually pure condensation at this lower temperature. The condensate in the second section takes place with the aid of a set quantity of cooled liquid, preferabl from the tank, from which the mixture escapes, or with that of a fluid of similar and suitable composition. The currents of liquid and vapour can intersect, or flow in the same of opposite directions. The first section can be an indirect heat exchanger with metal interchange surface, and the second a material exchange base.

Description

DR.-ING. BY KREISLER DR.-ING. SCHÖNWALD DR.-ING. TH. MEYER DR. FUES DlPL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLDPSCH DIPL.-ING. SELTING

5 COLOGNE 1, DEICHMANNHAUS

Cologne, November 5, 1973 Kl / En

Georg Guido Helfrieh, 5342 Rheinbreitbach, Slmrockstrasse 29

Method and device for reducing emissions organic_Dämgfegemische from Lagertankeη

Addendum to patent (patent application P 23 43 08l.1-22)

The invention relates to a method and a device for Reduction of emissions of organic vapor mixtures from storage tanks.

It has already been suggested that the vapor emission from storage tanks with stored liquid mixtures (e.g. gasoline) due to temperature-related (weather conditions) or operational-related (Filling, emptying) Breathing by cooling the gas (e.g. air) vapor mixture leaving the tank with simultaneous to reduce partial condensation of the vapors. The amount of vapor condensing in the presence of inert gases can do something has also already been proposed - at the same temperature level the cooling can be increased considerably if the · cooling / condensation either in a heat exchanger with sprinkled surface or in a direct heat exchanger with a certain liquid mixture in a certain amount he follows. This liquid mixture can mainly be taken from the tank from which the gas-vapor mixture escapes, or it must be put together appropriately, e.g. if the emissions from several tanks are combined be. The cooling / condensation described, for example, can reduce the amount of vapors that are emitted from a fixed roof tank with

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■ 2355238

- 2 gertem super fuel with the composition according to the number table

Number board 1 bration Comgonent Concentration toi- * C 5 and iso C 4 0.62 Γ I! C 4 9.58 Il C 5 9 * 19 Il C 6 16.80 ti C 7 9.07 It C 8 18.66 Il C 9 29.70 Il C 10 6.38

escapes in the saturation state at 23 ° C, considerably reduced as can be seen from the number table 2.

Number board 2 Amount of steam Cooling up with sprinkling
{1 = 10) to ° C Condensed amount of vapor in $ 6 0 O of the supplied 56 + 23 (entry) without sprinkling 76 0 0 84 - 10 20th 90 - 20th 36 ■ approx 95 - 30 53 - 55 67 9o

1 in the number table 2 is the ratio of the amount of sprinkling to the amount of vapors supplied. 1 has for practical Purposes a value between 5 and 10. The amount is useful the irrigation liquid greater than the amount of vapors supplied; up is the amount of liquid due to the economy of the procedure, because if there is too much

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too much cold and thus too much energy is used. In this way, for example, a considerable, environmentally protective effect can be achieved which, in the case of the cooling / condensation process with sprinkling, requires a considerably lower cooling capacity than the process without sprinkling. If, for example, the gasoline from 1000 nr / h tank breathing, which is saturated by a stored super fuel with the composition according to number table 1 ^{at atmospheric pressure and 2J 0} C, is condensed out to 10% of the amount escaping from the storage tank, this results at 45 ° C condensation temperature for the refrigeration machine process required for cooling, the ratios according to table 3,

The lower required chiller power in the event of the method with sprinkling has a larger amount of heat to be dissipated in the absolutely higher amount required Cooling temperature their cause. In the example according to number table 3, the required amount of sprinkling is ten times as high the air-fed damper antenna.

Number board 3

• Cooling / condensation without sprinkling with sprinkling

(1 = 10)

required

Cooling temperature t _v C

Evaporation temperature of the refrigeration

-55

-30

process t C -TO - 45 ■ heat to be dissipated
amount at t in
kcal / h ° 18 ^ .000 222,000 required lei
output in kW (cooling;
machine process) 241 204 .

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A tube cooler apparatus for carrying out the cooling / condensation with simultaneous sprinkling is shown in FIG. The implementation of the cooling / condensation is also possible in an apparatus with packing according to FIG. 2. An essential, limiting feature of such an apparatus very often the low permissible pressure loss on the gas-vapor side, if the cooling / condensation apparatus is connected to the gas / vapors room without the use of e.g. a fan (risk of explosion) a storage tank must be connected, which is generally only designed for overprints up to a maximum of 100 mm water column is. Here the indirect, e.g. tube coolers, are superior to the direct, packed coolers.

On the one hand, the sprinkling ensures the necessary exchange of substances between the gas-vapor phase and the liquid phase. In addition, the falling film covers the heat exchanger surface and prevents the build-up of water ice when the temperature falls below the zero degree C limit. Now is sufficient Amount of vapor in the gas / vapor mixture of the falling film is not always necessary to achieve this last-mentioned effect. The irrigation of the radiator pipes naturally has the accompanying effect a reduced heat transfer coefficient for the cooling apparatus. This reduction is due to the thermal resistance of the trickle film.

This disadvantage can be avoided with surface coolers with the same relative liquid supply for the mass transfer and even a slightly better degree of condensation with otherwise the same cooling temperature if the cooling / condensation is divided into two sections. In the first part, isobaric cooling to the cooling temperature t " is carried out without sprinkling, with simultaneous partial condensation; this takes place in a direct cooler with a metallic heat exchange surface, eg a tube cooler with low pressure loss. The second part of the condensation then takes place practically isothermally on one or a few mass transfer trays.

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The invention accordingly relates to a method for reduction the vapor emission from storage tanks through cooling and condensation of that escaping from a tank as a result of displacement Air or gas / vapor mixture according to patent

(Patent application P 23 43.081.1), which is characterized Is that the cooling / condensation that can be carried out at the same time in a practically isobaric section with cooling and condensation from an initial temperature to a temperature t "and in a subsequent practically isobaric-iso-

XS.

thermal section with practically pure condensation at a Temperature t "is subdivided, with the condensation in the second Section with the help of a certain amount of a cooled liquid, preferably carried out from the tank from which the air or gas / vapor mixture to be cooled escapes, or with the help of a liquid similar, more appropriate Composition. ':

Sprinkling liquid and air or gas-vapor mixture advantageously performed in countercurrent. But they can also be conducted in direct or cross-flow.

The invention also relates to a device for reducing the vapor emission from storage tanks by cooling and Condensation of that escaping from a tank as a result of displacement Air or gas / vapor mixture according to patent .........

(Patent application P 23 43 081.1) ,. those from an indirect heat exchanger with a metallic surface, which is combined with at least one mass transfer tray.

The heat exchanger preferably consists of a tube exchanger, which is expediently arranged vertically and its cooling tubes at one end with at least one mass transfer tray are connected.

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Pig shows an apparatus for carrying out the method according to the invention. 3: The tube cooler 1 is from the bottom to flows through the top of the gas-vapor mixture. At the lower end there is an inlet 2 for the gas / vapor mixture and an outlet> attached for the condensate. The gas / vapor mixture flows through the tubes 4, which are cooled with a coolant, from bottom to top of the heat exchanger. At least one mass transfer tray 5 is arranged above the actual tube cooler. By a line 6 is applied to this mass transfer tray sprinkling liquid.

The mass transfer trays, which are arranged above the cooling tubes, can be designed as desired. To be favoured however, such bottoms in which the pressure loss is as low as possible, such as the bell bottom drawn.

In addition to coolant inlet and outlet 7, the device naturally has at the upper end an outlet for the cooled gas-vapor mixture.

When carrying out the method according to the invention, the replacement floor is charged with the full required amount of irrigation, which must be cooled to an appropriate temperature so that the required cooling temperature t _K in the air-vapor mixture is maintained when the heat is supplied by the isothermal vapor condensation.

It is also possible to additionally cool the replacement floor.

Instead of a mass transfer tray, an equivalent, sprinkled packing layer can also be used.

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Claims (8)

Pa t e η t a η s ρ r ü ehe / 1) / Process for reducing the vapor emission from storage tanks through cooling and condensation of the air or gas / vapor mixture escaping from a tank as a result of displacement according to patent ........... (patent application P 23 4> 08l. 1), . characterized in that the cooling / condensation, which can be carried out at the same time, is subdivided into a practically isobaric section with cooling and condensation from an initial temperature to a temperature t _v and into a subsequent practically isobaric isothermal section with practically pure condensation at a temperature \ _v , wherein the condensation in the second section is carried out with the aid of a certain amount of a cooled liquid, preferably from the tank from which the air or gas / vapor mixture to be cooled escapes or. . with the help of a liquid of a similar, appropriate composition. 2.) The method according to claim 1, characterized in that to cooling air or gas / vapor mixture. and liquid for the isobaric-isothermal cooling section in countercurrent or in Direct or cross-flow. j5) Device for carrying out the method according to patent (patent application P 2j5 ² O 081.1)., characterized by a first part consisting of an indirect heat exchanger with a metallic exchange surface and at least one mass transfer tray as the second part. 4) Device according to claim 3 *, characterized in that the mass transfer tray in the direction of flow of the gas / vapor mixture seen at the upper end of the heat exchanger is arranged. . 50 98 19/0230 5) Device according to claims jj ^and d 4, characterized in that the indirect heat exchanger is a preferably vertically arranged tube exchanger. 6) Device according to claim 5 *, characterized in that the Cooling tubes at one end with at least one mass transfer tray are provided. 7) Device according to claims 3 to 6, characterized in that that the mass transfer tray is designed as a packing layer. 8) Device according to claims 3 to 7 , characterized in that it sump side via a supply line for the gas-vapor mixture with the vapor space of a storage tank and at the top via a pump and line with the liquid space of the storage tank and finally with a line for the return of the condensate connected to the storage tank. 50 98 19/0230