SU1738721A1 - Installation for storing volatile liquids - Google Patents

Abstract

Usage: storage of easily evaporating liquids in tanks and can be used in the oil producing, petrochemical and chemical industries. The essence of the invention: the installation is equipped with a two-section collector (DL) with vacuum fittings for placement in the lower section of the spent sorbent, and in the upper section cleaned with a heater (P), a condenser (K) and a spray gun (P). DS is connected to the drain pipe of the tank. P installed inside a cylindrical tank and connected through the P to the bottom of the DS. Capacity through the atmospheric pipe is connected via K with a vacuum pump. 1 il. sl C

Description

The invention relates to the storage of highly evaporating liquids in tanks and is intended for the storage of dimethyldichlorosilane used in the manufacture of silicone rubbers.

Installations for storing easily evaporating liquids, in particular oil and petroleum products, are known, which contain a tank with pressure alarms, pipelines and a vapor condensation device located both on the tank and inside or outside it. As a cooling fluid supplied to the annulus of the condenser, special refrigerant or product from the bottom of the tank.

The main disadvantage of these installations is their low operational

reliability due to heating of the coolant in the vapor condensation device.

Another disadvantage is the low degree of trapping of toxic and harmful vapors formed during storage of products. This is explained by the fact that the air flowing in from the various leaks enters the condenser together with the vapor. The presence of air contributes to a reduction in the heat load of the condenser due to an abrupt decrease in the heat transfer coefficient for the condensing vapor. In addition, the gradual accumulation of air in the vapor space of the condenser can lead to the release of vapor to the environment.

A known reservoir for storing easily evaporating liquids, comprising a housing with a bottom, a lid, installed in the center of the last branch pipe with a safety device, a sheath made of elastic material fixed in the branch pipe around its perimeter, forming an air chamber to reduce fluid loss.

The disadvantages of this tank are the structural complexity, the low effective volume ratio, since its upper part is not to be filled with the product, but is a superstructure for storing vapors.

A known device for storing easily evaporating liquids, comprising a reservoir, a drop separator, pipelines, a device for trapping liquid vapors, made in the form of a cylindrical container filled with a liquid sorbent and having a steam jacket, a bubbler, a pipe for draining the sorbent and a message to the atmosphere.

The main disadvantage of the known installation is low efficiency. This disadvantage is due to the fact that the device for vapor recovery does not provide for the possibility of desorption of the absorbed substances from the sorbent. For this reason, the latter is not used in the future with the loss of sorption capacity. Fresh sorbent is used instead.

The purpose of the invention is to increase the efficiency of the installation, by eliminating the loss of the sorbent.

Equipping the installation with a two-section collector, a heater, a condenser, a spray gun, and a container connection with a vacuum pump allow the regeneration of the spent sorbent to be carried out with simultaneous release of the absorbent in pure form.

The drawing shows a device for storing highly evaporating liquids, a general view.

The installation includes a tank 1, a drip drop 2, a pipeline 3 with a valve 4 mounted on it and a device for collecting liquid vapors stored in the tank.

The device for vapor recovery includes a cylindrical tank 5 filled with a liquid sorbent (I-8a industrial oil), a two-sectioned collector 6, a heater 7, a spray gun 8, a condenser 9, a vacuum pump 10, a Tseiss 11 interferometer, a vacuum tube meter 12, pipelines

13 and 14 with valves 15-23 mounted on them.

Capacity 5 is equipped with a steam jacket 24 and process connections: 25 nitrogen supply, 26 - communication with the atmosphere, 27 - supply of the gas-vapor mixture, 28 - sorbent discharge, 29 - sorbent supply. Inside the tank is the bubbler 30 and the spray 8. As a spray

0 used a nozzle type jet nozzle. This nozzle has a number of structural (ease of manufacture) and operational (high spray quality) advantages. A feature of her

5 are a short cylindrical channel with a diameter of 1.2 mm, a length of 2 mm and a cone inlet and outlet with angles of 30 °. The Zeiss Interferometer is used to measure the concentration of an absorbent in purified air.

0 The installation works as follows.

When filling the tank 1, the valves 4, 15 and 23 are opened. The incoming liquid displaces the vapor-air mixture into

5 pipeline 3. Through the pipeline 3, the PVA enters the droplet separator, where large droplets of liquid are separated from it. Next, the mixture through pipeline 13 is transferred to bubbler 30 and dispersed in the sorbent in the form of bubbles. The vapors contained in the mixture are absorbed by the sorbent, and the purified air is vented through the valve 23 and the interferometer 11 to the atmosphere.

When storing the liquid, the installation works in the same way.

When emptying the tank 1, the valves 4, 15 and 23 are opened and the liquid is pumped over by a centrifugal pump. As the fluid in the reservoir drains,

0 vacuum, under the action of which air leaks. Air is sucked at the interferometer 11, then through the valve 23, the bubbler 30 and the drip gutter 2 enters the reservoir. When moving through the sorbent, the bent air is freed from moisture vapor, which cannot be allowed into the tank.

Over time, the sorbent is saturated with vapors of the stored liquid and loses its sorption (protective) ability. When overshoot occurs (the absorbent concentration in the exhaust gas exceeds the maximum permissible value), the tank 1 is connected to a spare device for

5 vapor recovery, and in this desorption is carried out, for which they close valves 15 and 23 and open valves 16 and 17. Drain the spent sorbent into the lower section of the collector 6. At the same time, the heating steam is fed into the heater 7, into the jacket 24 and

the cooling agent in the annular space of the condenser 9. Then close the valve 17 and open the valve 22.

Begin the evacuation of the tank, turning on the vacuum pump. The evacuation of lead to a residual pressure of not more than 0.3-0.4 kPa. The preliminary evacuation of the tank and the maintenance of the residual pressure in the specified interval during spraying provide, firstly, a high potential for the desorption and condensation processes, since the resistance of heat and mass transfer in the external phase is significantly reduced due to the absence of an inert medium (air), secondly required for the spraying of the sorbent pressure drop across the nozzle; thirdly, timely removal from the desorption zone of the resulting vapors.

Upon reaching the specified residual pressure, valves 18 and 19 are opened and the sorbent is fed with nitrogen to the preheater 7. In the preheater, the sorbent is heated to a temperature determined by the ratio

The Tycrp + A / Erg / Sn / He A U,

where Tagr - temperature of the sorbent, ° C;

Bp is the boiling point of the absorber to be removed at a residual pressure of 0.3–0.4 kPa, ° C;

A is the coefficient taking into account the change in the heat of phase transformation of the absorbent with a change in its content in the sorbent;

g is the heat of phase transformation of the absorbent, J / kg;

pp is the density of the regenerated sorbent, kg / m3;

Sn is the heat capacity of the sorbent saturated with absorbent, J / kg K;

p is the density of the sorbent saturated with absorbing, kg / m3;

A U is the amount of absorption, necessary to remove during desorption, kg / kg, perceived heat from the heating wall. From the preheater, the sorbent enters the nozzle 8, by means of which it is sprayed in the tank. When the heated sorbent is sprayed due to the accumulated heat, it boils violently, accompanied by intense evaporation of the absorbed substances.

The preheating of the sorbent, while ensuring the required degree of desorption, makes it possible to obtain a spray more uniform than when it is sprayed in a cold state. This is explained by the fact that in the first case the forces applied to the destruction of the jet are more evenly distributed (boiling occurs throughout the entire volume of the sorbent). The increase in the dispersion and uniformity of the spray is also affected by a decrease in the coefficients when heated.

kinematic viscosity and surface tension.

The regenerated sorbent is collected on the bottom of the tank and flows into the upper section of the collection. The absorbent vapors formed during the evaporation flow into the condenser 9 where they condense. The condensate is discharged into an airtight container, from where it can be returned to the tank. In order to avoid condensation of steam on the walls of the tank, the latter are heated by steam supply to the jacket.

The spraying process is stopped as soon as in the measuring glass installed in front of the valve 19, along the boundary

0 between the sorbent and nitrogen. To do this, shut off valve 19. Nitrogen enters the desorption zone and further into the condenser dramatically worsens the conditions of distillation and condensation of the absorbent and may lead to its release

5 into the surrounding atmosphere.

The container is depressurized, for which the vacuum pump is turned off, the valves 22 and 16 are closed and the valves 23, 20 and 21 are opened. At the same time, the steam supply to the heater, jacket of the container and the cooling agent to the condenser are turned off. The regenerated sorbent from the upper section of the collector 5 is squeezed with nitrogen into the tank. On filling capacity close

5 valves 20 and 21 and open valve 15. The vapor recovery device is ready for further operation.

Example. Dimethyldichlorosilane is desorbed from the industrial

0 oil And - 8a. Pre-create a vacuum pump 10 vacuum in the tank 5 with a residual pressure of 0.3 - 0.4 kPa. Next, the spent sorbent with an absorbent content of 0.65 - 0.8 kg / kg is heated in

5 heater 7 to 220-230 ° C and sprayed in the tank 1 at a pressure of 0.3-0.4 kPa. The hydraulic characteristics of the spray: the performance of the nozzle SF 110, m / s; injector flow ratio K

0 0.8; the average volume-surface (Zauterovsky) droplet diameter d32 is 250 μm; feed pressure of the sorbent to the injector Rpod 0,25 MPa.

After spraying and vapor condensation

5 absorbent in the condenser 9 receive a sorbent with a residual absorbent content of not more than 0.6 - 0.07 kg / kg The sorbent regenerated in a similar way is ready for subsequent operation.

Claims (1)

Invention Formula A device for storing easily evaporating liquids, containing a tank, a drop separator, pipelines, a device for trapping liquid vapors, made in the form of a cylindrical tank filled with a liquid sorbent, and having a steam jacket, a bubbler, sorbent discharge pipes, and an atmospheric one, characterized in that in order to increase work efficiency by eliminating sor0 losses bent, it is equipped with a two-compartment tank connected to the drain pipe of the tank with vacuum fittings for placement in the lower section of the spent sorbent, and in the upper section cleaned, with a heater, a condenser and a sprayer installed inside the cylindrical tank and connected through the heater to the bottom of the collector the tank is connected via a condenser with a vacuum pump through an atmospheric pipe. W C / iuS Condensate L