SU1526718A1 - Method and apparatus for liberating mass-exchange apparatus from explosion-fire hazardous products - Google Patents

Abstract

The invention relates to the prevention of explosions and fires in distillation and absorption plants. The aim of the invention is to increase fire and explosion safety by accelerating the discharge of liquid fire and explosion hazard products from the rectification column plates. The method of removing pressure-exchanging apparatus for masses from explosive products consists in stopping the supply of raw materials, direct steam and irrigation, removing liquid products from the plates of the apparatus by gravity followed by degassing the apparatus with an inert gas or water vapor. reduce and maintain until complete removal of the liquid phase in the range not lower than atmospheric and not more than the value determined by the formula P _C = 2C _X √H ^. F / ϕ ^. * 98M√2G ^{. D.} Τ ^. SQ / S, and at the new start-up of the mass-exchange apparatus, before supplying the working media, it is filled with inert gas until the working pressure is reached. A device for releasing an overpressure mass transfer apparatus consists of a hermetic compensation tank, a valve that closes the drain opening of the optimum cross section and is installed in the pocket of the working sheet of the column; liquid whose boiling point is higher than the maximum temperature in the bottom of the column. The bellows box is connected through a connecting tube with a sealed compensation tank containing a piston and a compensation spring. 2 sec. f-ly, 3 ill.

Description

The invention relates to the prevention of explosions and fires in distillation and absorption plants.

The purpose of the invention is to reduce the time (up to 20 minutes) for emergency removal of fire and explosion hazardous liquid products from disc masking machines operating under excessive pressure.

On fi. 1 depicts a mass-type container, a piece of apparatus equipped with contact plates of the proposed design; in fig. 2 shows a section A -A in FIG. I; in fig. 3 shows a section BB in FIG. 2

A mass transfer column 1 (Fig. 1), equipped with contact plates 2. containing working sheet 3, on which valves 4 with displaced center of gravity and pockets 5 are mounted, is equipped with raw material supply lines, live steam, irrigation and vapor extraction lines and bottoms fluid. The device is also equipped (Fig. 2) with a drain valve 6 and a hole 7, a rod 8, a bellows box 9, a blind flange 10, a bracket-11, a spring 12, a stopper 13, a connecting tube 14, a cap nut 15, a fitting 16, a compensation capacity 17 It contains a piston 18 and a compensation spring 19. In this case, a drain valve 6 and a compensation capacity 17 are located in the pocket 5 (Fig. 2) of each plate in the liquid phase; a bellows box is located under the canvas pocket 5 of each plate. 9 and connecting tube 14. Drain valve 6 yvaet discharge outlet 7 and rigidly associated with the rod 8 bellows box 9 which is attached to the flange 10 glu.hom brackets 11 to the bottom web pocket plates

In order to provide the necessary rigidity, the bellows box 9 is provided with a spring 12 and is filled with an inert highly boiling liquid. In order to facilitate the filling of the inert fluid, the bellows box 9 in the upper plane has a plug 13 and communicates with the compensation tank 17 through a connecting tube 14 fixed by a cap nut 15 in the conical seal 11G1 of the pen 16.

The proposed device works as follows.

In the event of an emergency at the installation in the mass transfer column 1 (Fig. I), operating under excessive pressure, the supply of raw materials, live steam and irrigation is stopped. The bottom liquid is withdrawn from the bottom of the column, and from the upper part, the columns simultaneously discharge the vapor phase to the flare, and the pressure in the vapor space of the apparatus decreases even when the pressure value is equal to I ,, on the pocket pocket 5 of the contact plate 2 valve 6 ( Fig. 3) opens the drain hole 7. The valve 6 opens due to the action of the rising P1 current 8, which is rigidly connected to the bellows box 9, which, when the pressure value is equal to PC in the steam space of the column, expands under the action of the spring 12. The inertial fluid through the connecting tube 14 from the compensation tank 17 under the action of the piston 18 and the compensation spring 19 flows into the bellows box 9 until the pressure in the bellows box 9 reaches the pressure value P,. phase out of the apparatus.

The liquid phase is removed from the pockets 5 (Fig. D) of the contact plates 2, entering the annular gap formed between the canvas of the pocket 5 and the valve 6 (Fig. 3), and the size of the side surface of the annular gap should be equal to the area of the drain hole 7. After drainage liquid phase from the column to the apparatus is supplied inert0

five

0

about

0

five

O

This gas or water vapor for the purpose of degassing the apparatus.

The boiling point of the inert liquid with which the bellows box 9 is filled must be higher than the temperature in the cube of the mass-replacement apparatus. The compensation spring 19, in addition to the function of compensating for the change in the magnitude of the pressure in the system, performs the function of compensating the magnitude of the thermal expansion of the inert liquid.

To start the mass transfer apparatus equipped with the proposed devices before supplying the working media, the column is filled with an inert gas to the operating pressure, the bellows box 9 and the spring 12 are compressed, the rod 8 is lowered, and the valve 6 closes the drain hole 7 The inert liquid displaced from bellows box 9, flows through the connecting tube 14 into the compensation tank 17, accumulating under the piston 18, supported by the compensation spring 19.

The amount of excess pressure in the vapor phase of a mass transfer column apparatus is determined by the formula

2.CWFvF g ..S-S

where I. is the vapor phase pressure at which the liquid phase is being discharged, N / m;

// - the height of the liquid level in the pocket of the contact plate, m; C, the total stiffness of the spring-liquid bellows box, N / m,

F is the surface area of the pocket of the contact plate, J is the coefficient of fluid flow in

round hole, 0.68; g - free fall acceleration

jet m / s;

D is the optimum diameter of the drain hole, m;

t is the required time for emptying the pocket of the plate from the liquid, s; S is the cross-sectional area of the bellows box, m;

q is the total weight of the valve and stem, N. The magnitude of the excess pressure in the vapor phase of the mass exchange column apparatus PC, at which the liquid phase is discharged from the apparatus, is obtained from the equilibrium of forces applied to the sensitive element of the device (bellows box

c,.,. s +.

(2)

moreover, in general, for any overpressure in the vapor phase of the apparatus, (.ch whether f. S-bq, valve 6 is closed, and if + q, T (J valve 6 is open (lt, where Cd / is the force due to elastic

resistance of spring-liquid bellows box, N; PcS is the force due to the pressure of the medium of the vapor phase PC, when the fluid is discharged from the pocket, on the spring-liquid bellows box, H; q is the force due to the weight of the valve 6 (Fig. 2) and ujTOKa 8 on the spring-liquid bellows box, H; Cx - total stiffness of the spring-liquid bellows box, N / m;

/ - movement of the valve 6 over the cloth of the pocket of the plate 5, m; S is the cross-sectional area of the bellows box, m.

In order to ensure the required flow time and reduce the flow resistance of the fluid, the size of the side surface of the annular gap formed between the cloth pocket of the tray 5 and valve 6 when the fluid is discharged from the pocket must be equal to the area of the drain hole I, which has a diameter D

D

then

2C.YU 1.

 S

(7)

0

The resulting equation (6) allows r to determine the vapor phase pressure in any mass transfer apparatus when implementing the proposed method, and the inequality

CJ PcS + q O determines these, i.e., the pressure of the vapor phase in the apparatus is reduced and maintained until the complete removal of the liquid phase in the range not lower than the atmospheric and not more than the value determined by form 5 (6).

When choosing the optimum diameter of the drain hole, the necessary time for the release of the mass transfer apparatus is determined by the time of stability of metal structures in case of fire (25-30 min). In connection with this, a whole series of TI times is taken at once; Tg; Ts; T ,, and any

T, 25 min

then, knowing the number of plates n (and, consequently, the pockets), in the apparatus determines the necessary time for emptying the pocket of the plate from the liquid t ,. For single-flow contact plates, with consecutive emptying of the pockets in the column,

moreover, the outflow time of the liquid t from the pocket of a mass exchange plate of constant height and the cross section F, is determined from the well-known differential equation of the outflow of liquid

dr, P dH l / V2gЯ

integrate from // to O get

G .. f.

where l is the coefficient of fluid flow in

round hole;

C is the acceleration of the free fall of the jet, m / s.

Substrate.1 (2) in (3) receive,

Substrates (4) in C.F

get

LTSO751

- PcS + g.

From (5) the pressure in the vapor phase of the column is found, at which the liquid phase is discharged, P, T,

T2

-, T2 -,, ..., T, -.

-li

 P.

For each n, T2, tz, ..., t, by equation (3), a series of diameters of drain holes DI, DZ, D3, -., Di

35

D

ISFifr

40

at

and a number of areas of the drain holes f, / 2, / 3, ..., / 1, and from the resulting row of holes (f)) are those holes for which the following inequality holds:

f.F.

For column 1 (Fig. 1), the release time of the bottom space is calculated, t.

 T

V.

N

where Vi, is the volume of the cubic space, L is the productivity of the bottom pump,

50

55

From the obtained number of devices, those devices are rejected for which the following inequality holds: T, t

For the remaining number of holes, characterized by the following parameters:

TI; 12...

T; T ....

DI; D-2 ...

/ ,; / 2 ...,

according to equation (6), a number of overpressures in the vapor phase of the apparatus are determined, at which the liquid phase is discharged from the pockets of the plates of the PCI apparatus; RS2 ...

In addition, for each D ... it is determined / I, / 2 ... and for constructive reasons for each D Dz ... and / i; / 2, the geometrical dimensions of the device parts are selected and, using known formulas, the total stiffnesses of the spring-liquid bellows boxes are calculated from,:; Cx2 ... In the resulting series of devices characterized by the following parameters:

T; Tr ... / ,; / 2 ...

TI; T9 ... Cb1; Cx2 .--

DI; D2 ... S; 52 ...

 /2...q qi..and in the obtained pressure range Pc Pc2 ... any pressure and the corresponding device provide the necessary reduction in the time of emergency removal of explosive liquid-hazardous liquid products from the dishwashers operating under overpressure to 25 min (initial condition T, 25 min).

.. „

From the resulting pressure and pressure yes

devices choose the best design considerations for the minimum metal consumption and, consequently, the minimum cost. The resulting pressure Pd and the corresponding device, characterized by the following parameters: Ti; TI; DI; / i; / i; (., 1; Si; q, are optimal and therefore DI; / i; / i are optimal.

Claims (2)

1. A method of freeing mass exchangers from explosive fire hazardous products, consisting in stopping the supply of raw materials, live steam and irrigation, removing liquid products from the bottom of the column, removing liquid products from the plates of the apparatus by gravity followed by degassing the apparatus with an inert gas or water steam, characterized in that, in order to increase the fire and explosion safety, by accelerating the discharge of liquid fire and explosion hazardous products from the plates of the distillation column, simultaneously with the removal of the bottom liquid of the pressure e steam 0 with 0 five about five 1 g the phases in the apparatus are reduced and maintained until the complete removal of the liquid phase in the range not below atmospheric and not more than the value expressed by the formula „ICjH.F 9 lcU2 & -out 5 where PC is the vapor phase pressure at which the liquid phase is being discharged, С - total rigidity of the spring-liquid sploff box, N / m; F is the surface area of the pocket of the contact plate, H is the height of the liquid level in the pocket of the contact plate, m; C - the coefficient of fluid flow in round hole, 0.68; g - free fall acceleration jets, D is the optimum diameter of the drain holes, m; t is the required release time liquid plate pockets, s; S is the cross-sectional area of the bellows box, q is the total weight of the valve and the choke, I, and at the start of the mass-exchange apparatus, before the worker is fed. its media is filled with inert gas until the working pressure is reached. 2. A device for releasing the mass exchangers from explosive fire-hazardous products, containing valves with an displaced center of gravity, overflow devices and pockets with drain holes in the working web of the plate, characterized in that it is additionally equipped with a disc valve connected to a spring-loaded bellows filled with an inert liquid with a boiling point higher than the maximum temperature in the bottom of the column, as well as a compensation tank with a spring-loaded pressure filled with inert fluid bone cavity and connected to the bellows through a conduit, the poppet valve and the compensation tank located on the canvas pocket from the working fluid, and bellows - the opposite pocket and fastened to the web through kronschteynov. Live steam Irrigation  -g . Cd5. Yid - 5-5 / f  7 i. U2.5