What role do the internal volume and internal pressure ratio of Wu Leng’s chlorine liquefaction unit play in actual operation?

It’s just an energy-saving device; in practice, few people pay attention to it. The main focus is on adjusting the energy level, and when automatic mode is used, the unit adjusts itself to the optimal state. You can look up relevant information regarding over-compression and under-compression. I rarely use an economizer here; the gasification process takes place in the shell side and then returns to the compressor head

Reply to 2# flay0303 Oh, thank you

This post was last edited by szt001 on 2010-12-3 at 10:41. Screw-type refrigeration compressors belong to the category of positive-displacement compressors; they feature internal compression and have a certain internal pressure ratio. The operating range of such compressors is very wide, and their operating pressure ratio (condensation pressure/evaporation pressure), which is also the external pressure ratio, varies depending on the operating conditions. This requires that the internal pressure ratio of screw refrigeration compressors change accordingly, so as to make it close to or equal to the external pressure ratio, thereby minimizing energy consumption and ensuring more efficient operation. Otherwise, an isochoric compression or expansion process will occur, resulting in increased energy consumption by the compressor. The greater the difference between the internal pressure and the external pressure, the more work is consumed. Therefore, in order to enable the machine to operate economically over the long term, it is necessary to adjust the internal volume ratio of the machine so that the internal pressure ratio is close to or equal to the external pressure ratio. The formula for calculating the external pressure ratio is as follows: Condensation pressure + Exhaust pressure (gauge pressure) + 0.1 = External pressure ratio; Evaporation pressure + Suction pressure (gauge pressure) + 0.1 = Internal volume ratio. The mechanism for adjusting the internal volume ratio consists mainly of an electromagnetic (or manual) directional control valve and a slide valve for controlling the internal volume ratio, as shown in the diagram. The mechanism for determining the internal volume ratio consists mainly of a displacement transfer rod and a linear potentiometer. In the diagram, L1 represents the size of the exhaust port of the slide valve, and it is this size that determines the internal volume ratio of the machine. When a signal to increase the volume ratio is sent from the control panel, port P and port A in the directional valve become connected. The high-pressure oil coming from the oil filter passes through ports P and A of the directional valve, then enters the cylinder on the left side of the volume ratio piston via port SC-3. The oil on the right side of this piston flows out through port SC-4, passes through ports B and T of the directional valve, and returns to the compressor through the return oil pipe. As a result, the volume ratio piston moves to the right under the action of the pressure difference between the front and back, causing the volume ratio spool to move as well; consequently, the exhaust flow at port L1 gradually decreases. Conversely, when the volume ratio is reduced, port P and port B in the directional control valve become connected, as do ports T and A. The high-pressure oil coming from the oil filter passes through ports P and B of the directional control valve, then enters the cylinder on the right side of the piston with the variable volume ratio, via port SC-4. The oil on the left side of this piston flows out through port SC-3, passes through ports A and T of the directional control valve, and returns to the compressor through the return oil pipe. Under the action of the pressure difference between the front and back, the piston with the variable volume ratio drives the slide valve with the same variable volume ratio to move to the left, causing the exhaust port L1 to gradually increase in size. The position of the slide valve is sensed by a displacement transfer rod and sent to a potentiometer; the resistance value measured at the potentiometer is processed and converted into a value representing the volume ratio, which is then displayed. When the piston reaches the far right end of the cylinder, the exhaust opening is smallest, resulting in a maximum volume ratio of 5. When the slide valve reaches its left limit position, the volume ratio is at its minimum value of 2.5. The internal volume ratio can be adjusted continuously within the range of 2.5 to 5.

Reply to 4# szt001: Few people are able to adjust the internal volume ratio properly; it seems that automatic control is now used in such systems, and there aren’t very high technical requirements for refrigeration technicians these days. If you need information, you’ll have to check the company’s archives!

Hehe, the part where the economizer vaporizes flows through the shell side. Why is that?