Operating mode of a jet blower

The invention relates to the field of jet technology. After the required pressure of the gaseous medium at the gas inlet of a liquid-gas jet apparatus is obtained, the ratio of the liquid pressure in the nozzle of the jet apparatus to the pressure at the outlet of the jet apparatus is reduced in magnitude. Such ratio is reduced in magnitude down to the value at which an abrupt increase of gas pressure occurs at the gas inlet of the jet apparatus. This value of the ratio is fixed or determines the minimum value for such ratio. Then the final value of the ratio of the liquid pressure in the nozzle of the jet apparatus to the pressure at the outlet of the jet apparatus is set. The final value of the ratio must be greater than the fixed one. The process provides an increased efficiency for a liquid-gas jet apparatus.

BACKGROUND OF THE INVENTION 
The present invention relates to the field of jet technology, primarily to 
liquid-gas jet apparatuses, which are intended for creation of excessive 
pressure in different industrial processes. 
The operational method for a liquid-gas jet apparatus is known, according 
to which a vacuum in a gas reservoir is generated owing to evacuation of a 
gaseous medium from the reservoir by the jetting of a liquid medium. The 
liquid medium under high pressure is delivered into the nozzle of a jet 
apparatus which is hydraulically connected to a reservoir (see, for 
example, book of K. P. Shumski, "Vacuum apparatuses and instruments", M., 
Mashgiz, 1963, p.476-477). 
However, liquid-gas jet apparatuses implementing such an operational method 
have a low efficiency factor (high energy consumption). Therefore they are 
not widely used. 
As the starting point for this invention the authors selected an 
operational process of a liquid-gas jet apparatus, consisting of feed of a 
liquid medium under high pressure into the jet apparatus' nozzle, 
discharge of the liquid medium through the nozzle, and evacuation and 
compression of a gaseous medium by the liquid jet flowing from the nozzle. 
The required pressure of the gaseous medium at the inlet of the jet 
apparatus is provided (see USSR Certificate of Authorship No. 754118, M, 
cl. F04 F5/02, 1980). 
The imperfection of this operational process is its low efficiency since 
the maintaining of the required pressure at the jet apparatus' gas inlet 
is accompanied by considerable energy losses. 
SUMMARY OF THE INVENTION 
The technical problem to be solved by this invention is an increase of 
efficiency of a liquid-gas jet apparatus due to reduction of energy losses 
in said apparatus. 
The solution of the problem is ensured by the following. The operational 
process of a liquid-gas jet apparatus, consisting of feed of a liquid 
medium under high pressure into a nozzle, discharge of the liquid medium 
through the nozzle, evacuation and compression of a gaseous medium by the 
liquid jet flowing from the nozzle, so that the required pressure at the 
gas inlet of the jet apparatus is provided, is supplemented by the 
following steps: after the required pressure of the gaseous medium at the 
gas inlet of the jet apparatus is obtained, the ratio of the liquid 
pressure in the nozzle of the jet apparatus to the pressure at the outlet 
of the jet apparatus is reduced in magnitude. Such is reduced in magnitude 
down to the value or magnitude at which an abrupt increase of the pressure 
of the gaseous medium occurs at the gas inlet of the jet apparatus. This 
value of the ratio is registered as the minimum value for such ratio. Then 
the final operational value or magnitude of the ratio of the liquid 
pressure in the nozzle of the jet apparatus to the pressure at the outlet 
of the jet apparatus is set. The final operational value of the ratio must 
be greater than the registered one. 
It is expedient to reduce the value of the ratio of the liquid pressure in 
the nozzle of the jet apparatus to the pressure at the outlet of the jet 
apparatus either by reducing the liquid pressure in the jet apparatus' 
nozzle or by simultaneous boosting of pressure at the outlet of the jet 
apparatus and reducing the liquid pressure in the nozzle of the jet 
apparatus. 
Experimental research has proven that specific pressures at the liquid 
inlet and at the outlet of a liquid-gas jet apparatus are required for 
maintaining the necessary pressure in any closed space, for example in a 
degasifier or in a vacuum rectification column. Because of the inaccuracy 
of existing calculation methods it is very difficult to ensure the 
efficiency factor of a liquid-gas jet apparatus to more than 30% when the 
optimal pressures at the liquid inlet and at the outlet of the jet 
apparatus are predetermined by calculations. It is ascertained that after 
the required gas pressure at the gas inlet of a liquid-gas jet apparatus 
is obtained, one may reduce pressure of the liquid fed into the jet 
apparatus, or boost pressure at the outlet of the jet apparatus, or do 
both simultaneously, while the gas pressure at the gas inlet of the jet 
apparatus remains near constant. However, each specific liquid-gas jet 
apparatus has its own range of values of the ratio of the liquid pressure 
in the nozzle to the pressure of gas-liquid mixture at the outlet, within 
which the suction gas pressure of this jet apparatus remains constant. 
This range depends on the individual design of the liquid-gas jet 
apparatus, the composition of the gaseous medium and other parameters. So 
in each specific case, after the jet apparatus comes into its normal 
operating regime, the ratio of the above pressures may be reduced by any 
of the possible methods (i.e. by reduction of the liquid pressure in the 
nozzle of the jet apparatus, by boosting the outlet pressure, or by a 
combination of both methods) in order to determine the ultimate minimal 
value of the ratio of pressures. To determine this value the ratio of the 
liquid pressure in the nozzle of the jet apparatus to the pressure at the 
outlet of the jet apparatus is reduced in magnitude down to the value at 
which an abrupt increase of pressure occurs in the gas delivery pipeline 
of the jet apparatus. Thusly the ultimate minimal value of the ratio of 
pressures is fixed. Next, the final operational value of the ratio of the 
liquid pressure in the nozzle of the jet apparatus to the pressure of the 
gas-liquid mixture at the outlet of the jet apparatus is to be set. The 
final operational value of the ratio must be greater than the fixed 
ultimate minimal value. This should allow for the required reserve 
depending on the stability of flow of the evacuated gaseous medium. 
Such provides an increase in efficiency of a liquid-gas jet apparatus 
without reduction of its capability.

DETAILED DESCRIPTION OF THE INVENTION 
The pumping ejector unit comprising a reservoir 1, a liquid-gas jet 
apparatus 2, a separator 3, pumps 4 and 5, and a control device 6 
(regulating valve, for example) can be cited as an illustration of an 
embodiment for implementing the process. 
The introduced process is implemented as follows: 
A liquid medium is delivered under pressure into the liquid-gas jet 
apparatus 2 by the pump 4. The liquid medium, flowing from the nozzle 7 of 
the jet apparatus 2, entrains a gaseous medium being received from the 
reservoir 1 through the gas inlet 8 of the jet apparatus 2. The liquid 
medium mixes with the gaseous medium in the jet apparatus 2. The 
liquid-gas mixture is compressed while passing through the jet apparatus 2 
and proceeds under pressure into the separator 3. Separation of the liquid 
and gaseous mediums takes place in the separator 3. The liquid medium is 
delivered from the separator 3 by the pump 4 into the nozzle of the jet 
apparatus 2. The compressed gaseous medium is delivered from the separator 
3 to consumers. 
In the discussion which follows P.sub.1 =the pressure of the liquid in the 
nozzle 7. P.sub.2 =the pressure of the liquid-gas mixture at the outlet 9 
of the jet apparatus 2. P.sub.3 =the gas pressure at the gas inlet 8 of 
the jet apparatus 2. After the required or operational pressure in the 
reservoir 1 is obtained (the pressure in the reservoir 1 is in accordance 
with the pressure P.sub.3 at the gas inlet 8 of the jet apparatus 2), the 
ratio of P.sub.1 to P.sub.2 is reduced in magnitude. Such ratio is reduced 
in magnitude down to a value when or at which an abrupt increase or 
discontinuous rise of P.sub.3 occurs. The value of the reduced ratio is 
fixed as the minimal permissible value of the ratio P.sub.1 /P.sub.2. Then 
the final operational for working value of the ratio P.sub.1 to P.sub.2 is 
set. The final value of the ratio must be greater than the minimal 
permissible value. In other words (P.sub.1 /P.sub.2) final&gt;(P.sub.1 
/P.sub.2) minimal, where to the value of (P.sub.1 /P.sub.2) minimal is 
fixed or determined when there is a discontinuous rise in P.sub.3. 
The reduction of the ratio of pressures is effected experimentally in one 
of the three ways--first by throttling of the liquid flow fed into the jet 
apparatus 2, second by boosting of the backpressure at the outlet 9 of the 
jet apparatus 2, or third by varying both the first and second 
simultaneously. 
Several variants of unit operation can be implemented after the permissible 
range of values of the ratio have been determined empirically. For 
example, the system can be furnished with the starting pump 4 and a pump 5 
joined-up in parallel. The pump 5 feeds the liquid medium under a reduced 
pressure to the jet apparatus 2, which ensures the required ratio of 
pressures. Such provides for both the starting condition and the operating 
mode of the liquid-gas jet apparatus 2. A reservoir with liquid (not shown 
in the drawing) can be used instead of the pump 4 in case the unit is 
seldom stopped during operation. Liquid from the reservoir can be 
delivered into the jet apparatus by means of a compressed gas, for 
example, from a compressed-gas cylinder (not shown in the drawing). In 
this case, after the normal operating mode of the liquid-gas jet apparatus 
2 is set, the reservoir with liquid may be disabled and the pump 5 may be 
started. 
The introduced operational process for a liquid-gas jet apparatus can be 
applied to various pumping-ejector units, which are used in petrochemical, 
food and other industries.