DE224059C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 224059 CLASS 27c. GROUP

ALBERT HUGUENIN in ZURICH.

Patented in the German Empire on October 9, 1908.

The invention relates to a method and a device for the bumpless connection of centrifugal compressors to pressurized lines, air tanks and the like.
If, when a centrifugal compressor is switched on in a pressurized line, it is initially started with the pressure valve closed and accelerated until the necessary pressure is achieved,

ίο then the connection with said line produce, so there are periodic pressure fluctuations in the supply line from Compressor. It takes an irregular pace with the same period on, partly accelerating and partly retarding. This very unpleasant appearance creates practically unusable operating conditions. The explanation of this phenomenon is very easy to see based on the characteristics of the centrifugal compressor.

In Fig. Ι the essential course of the pressure and power curve as a function of The delivery rate applied, the proof in question may be made on them.

2 shows the schematic arrangement of several centrifugal compressors a _x , a ₂ , «3 connected in parallel on a common air vessel c. The supply pipes from the compressors after the air chamber are each closed off from the air chamber by check valves b _v b ₂ , δ ₃ . It is the case that two compressors are working and that the third is to be switched on against a pressure p in the air chamber. This pressure p is plotted in the diagram in FIG. 1 and may correspond to the delivery Q ₁ for the pressure curve of the normal number of revolutions. The supply pipe from the compressor to the air chamber is closed by the aforementioned check valve. If the compressor is now started, at most the lower pressure p _{0 is reached} with the normal number of revolutions η and the corresponding power N ₀ when the pressure side is completely closed. Switching on is impossible in this way. First of all, the air chamber pressure p must be established in the pressure line of the compressor, and there is no other means than to increase the number of revolutions from η to n ₀ , which corresponds to the dotted pressure curve in the diagram (Fig. 1). As soon as this state is reached, the check valve begins to rise from its seat, for which purpose the pressure in the supply line has to exceed that of the air vessel by a very small amount so that the valve lift resistance can be overcome. If, however, a connection between the supply line and the air chamber is established, the compressed air begins to flow into the air chamber, which due to the nature of the characteristics, as can be seen immediately from the diagram, causes a further immediate increase in pressure. On the other hand, this combination of a sudden increase in pressure and a corresponding promotion corresponds to a considerable one

Claims (4)

Increase in the work consumption of the compressor, which leads to a sudden larger in- • is equivalent to the stress on the drive machine. If one considers z. If, for example, the registered promotion Q ₁ is due to this particular moment, it is easy to see that the increase in the pressure from p to P ₁ results in an increase in the power from N ₀ to N ₁ ίο has consequence. This sudden substantial increase in utilization but the drive machine will slow down its speed, with which the pressure will be restored will sink. So we return to the t5 the initial state back, and the steadily progressing Promotion will again produce a similar growth, what therefore is absolutely equivalent to a similar increase in performance. So you can see that according to the peculiar course of the characteristics of the compressor at such Start-up is in an unstable state of equilibrium, so that there is no damping is present, a continuous fluctuation of the delivery pressure will take place. The machine cannot be brought into a steady, uniform gait. In contrast, the essence of the invention is that the pressure line from Compressor forth final check valve is braked so that it is only gradually opens. In the drawing is a device used to carry out the new method illustrated in two embodiments (Figs. 3 and 4) for example. In Fig. 3, A ₁ denotes the pressure line of the compressor, B \ the non-return valve loaded by spring B _{1 towards the air chamber.} A steady load on the drive motor will evidently be achieved as soon as the check valve B \ is prevented from opening too quickly; this can be done in the following ways. The check valve B \ carries a spindle on which a piston D ₁ and a piston _{valve C 1 are} attached. The line G ₁ creates a pressure equilibrium between the point E _{1 of} the wind line and the annular space J _{1 of} the housing of the slide C ₁ and the piston D ₁ . The position shown corresponds to the rest position when the non-return valve B \ is closed. At E ₁ there is a slight constriction of the wind conduit. In this state, the compressor is started and initially only generates a pressure corresponding to the number of revolutions in its pressure line, which is closed on all sides. As soon as "this pressure has reached the amount that is necessary to lift the check valve B \ from its seat, thus creating a flow in the wind pipe, a pressure difference between E ₁ and -F _{1 will result as a result of the intended change in cross-section} assert in the sense that at F _{1 there is} an overpressure, at E ₁ a negative pressure, so that a resultant force is exerted on the piston D ₁ which prevents the non-return valve from opening rapidly. the feed line G _{1 is closed} by the piston _{valve C 1} and the piston D ₁ runs past the edge H _1. When the check valve is raised further, compressed air then flows directly from F ₁ to J ₁ , so that the fully open check valve B \ corresponds to the normal operating state, is completely relieved.The gradual opening of the check valve, which is achieved by the arrangement described, also ensures the constant load on the drive machine and thus prevents the occurrence of the previously unavoidable, highly disadvantageous pressure fluctuations. A second embodiment of the new device is shown in FIG. 4. Here, A ₂ again means the pressure line coming from the compressor, B \ the check valve spring-loaded by B _2. The spindle of the valve B \ _{carries a piston valve D 2} and a piston C ₂ in a special, self-contained housing. The line E ₂ establishes the direct connection between the compressor pressure chamber and this housing. The representation on the drawing corresponds to the rest position of the device. When the compressor is started, a pressure corresponding to the number of revolutions is set in the pressure line, which is closed on all sides. As soon as this is able to raise the check valve, a noticeable increase in pressure is generated in the compressor, which is now also transferred to piston C ₂ by virtue of pipe E ₂ . This prevents the check valve from rising too quickly, and thus prevents the compressor pressure from increasing too much. As the delivery increases, the piston C ₂ gradually closes the line E ₂ , while the piston slide D ₂ opens the connection F ₂ , so that when the no check valve B ' ₂ is fully raised, i.e. in normal operation, this is completely relieved again. ■ Sponsorship claims: i. Procedure for the bumpless connection of centrifugal compressors at ^ under .pressure standing lines, air tanks and the like, characterized in that the in the compressor prevailing pressure for braking the pressure line from the compressor final check valve is used, so that this opens only gradually. 2. Device for performing the method according to claim i, characterized in that that a piston and a piston valve are controlled so that they open the rigidly connected to them Delay check valve and fully open the valve in its end position relieve. 3. Embodiment of the device according to claim 2, characterized in that a line (G ₁ ) branched off at a constriction point (E ₁ ) of the pressure line leads to an annular space (J ₁ ) in which a piston slide (C ₁ ) and a piston ( D ₁ ) are arranged, which are rigidly connected to a check valve (B '\). 4. Embodiment of the device according to claim 2, characterized in that a line (E ₂ ) leads from the compressor pressure chamber into a closed cylinder in which the piston (C ₂ ) and the piston slide (D ₂ ) are located, and through the lines (F ₂ and G ₂ ) communicates with the space behind the check valve. 1 sheet of drawings.