A vacuum pump that draws air by periodically changing the working volume of the pump cavity (cylinder) due to reciprocating motion of the piston, also known as piston vacuum pump. The structure of reciprocating vacuum pump is similar to that of reciprocating piston compressor. During operation, the suction pipe is connected to the evacuated container, and the exhaust pipe is directly connected to the atmosphere. The pumping rate of reciprocating vacuum pump is 45-20000 cubic meters per hour, the limit pressure of single-stage pump is about 103 PA, and that of double-stage pump is up to 1 PA. Reciprocating vacuum pump can be used for vacuum distillation, vacuum concentration, vacuum crystallization, vacuum filtration, vacuum drying and concrete vacuum operation. If a condenser is installed at the suction port of the pump, the gas containing water vapor can be removed; if a filter is installed, the gas containing dust can be removed.
Working principle of reciprocating pump. The main components of the pump are cylinder 1 and movable block 2 in which reciprocating linear motion is made. The driving of the mobile village is completed by the crank link mechanism 3. In addition to the above main components, there are exhaust valve 4 and suction valve 5.
When the pump is running, driven by the motor, the piston in the cylinder will do reciprocating motion through the function of the crank connecting rod mechanism. When Wang room is waiting for GE to move from the storage end to the right end. As the volume of the left chamber of the cylinder increases, the density of the gas in the cylinder decreases, and the air extraction process is formed. At this time, the gas in the container enters the left chamber of the pump body through the suction valve 5. When the piston reaches its rightmost position, the cylinder is completely filled with gas. Then the piston moves from the right end to the left end, and the suction valve 5 is closed. The gas in the cylinder is gradually compressed as the piston moves from right to left. When the pressure of the gas in the cylinder reaches or slightly exceeds one atmospheric pressure, the exhaust valve 4 is opened to discharge the gas into the atmosphere and complete a working cycle. When the piston moves from left to right again, it sucks in a part of gas, and repeats the previous cycle, and so on, until the gas pressure in the pumped volume reaches the requirements.
In practical application, in order to improve the efficiency of air extraction, the pump mostly adopts double acting cylinder, that is, the piston can compress and extract air simultaneously in two directions (reciprocating), which is mainly realized by the valve. The domestic W-type reciprocating pump is a single-stage double acting pump.
Reciprocating pump has dry and wet. Dry pump can only pump gas, wet pump can pump gas and liquid mixture. There is no principle difference between the two in terms of structure, but the size of dead space and distribution mechanism in wet pump is larger than that of dry pump, so the limit pressure of wet pump is higher than that of dry pump. There are two types of reciprocating pumps, horizontal and vertical (domestic W and WL). The vertical pump is more advanced in structure and performance. It is a new generation of horizontal pump.
Advantage:
(1) The average power consumption is reduced by 1 / 3, and the energy saving is significant. For example, the original W5 power is 22KW, while wlw-200b is 15kw; the original W4 is 11kw, and wlw-100b is 7.5kW.
(2) The floor area is reduced by an average of 2 / 3. For example, the original W5 type occupies an area of 3.8m, while wlw-200b is 1.2m.
(3) Vibration reduction. WLW series pumps eliminate the S-wave inferior vibration and reduce the noise by more than 5dB on average.
(4) Long service life. The vertical pump has reasonable structure and uniform stress, which reduces the wear of each moving part.
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