[Mechanical Equipment Technology Edition] Daily Question 201709030 – Refrigeration Systems
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This post was last edited by YORK Industrial Refrigeration on 2017-10-9 at 15:32. Starting from now, in order to enhance communication among users, a 【Daily Question】 activity has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no scoring will be given after that period. Oil leakage in refrigeration systems is a fairly common issue. What are the causes of oil leakage? 1. At its core, considering the inherent properties of oil itself, when the oil temperature is too high, it becomes thinner; when the temperature is too low, it becomes thicker. Excessively high or low oil temperatures can cause oil leakage (analyze the reasons for high or low oil temperatures). 2. Moisture in the oil. 3. Poor sealing of the intake and exhaust check valves. 4. Problems with the oil return system. 5. Issues with the oil separation function (this situation generally does not occur). ================================ Premium promotions: Mechanical equipment——York screw compressors: maintenance procedures http://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrading York Quinton control centers http://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Overhaul of GEA Grasso screw compressors http://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors http://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese Maekawa MYCOM screw compressors http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1786445
(1) The oil level is too high; too much engine oil has been added. After relieving the pressure, drain the oil to the normal level ； (2) The return oil pipe is blocked. It can be checked and replaced ； (3) The installation of the return oil pipe (with a distance of 1–2 mm from the bottom part of the oil separation element) does not meet the requirements; it can be adjusted again ； (4) When the unit is operating under overload and at low pressure, the gas consumption increases; however, since the pressure in the gas storage tank remains high, this phenomenon does not occur ； (5) Internal damage to the oil distiller tank; it can only be detected through disassembly for inspection ； (6) Oil has deteriorated or been used beyond its expiration date ； (7) If the return oil check valve loses control, oil will flow back into the oil fine separator after the unit stops operating; this will result in oil leakage when the unit is started again ； (8) Damage or rupture of the air compressor oil fine separator element ； (9) There are leakage points at the minimum pressure valve, or the valve opens prematurely, resulting in low pressure inside the oil separator. This leads to a high concentration of gas in the oil mist; as a result, the flow velocity increases when the oil mist passes through the separator, the load on the separator increases, the separation efficiency declines, and fuel consumption rises.
(1) The oil level is too high; too much engine oil has been added. After relieving the pressure, drain the oil to the normal level ； (2) The return oil pipe is blocked. It can be checked and replaced ； (3) The installation of the return oil pipe (with a distance of 1–2 mm from the bottom part of the oil separation element) does not meet the requirements; it can be adjusted again ； (4) When the unit is operating under overload and at low pressure, the gas consumption increases; however, since the pressure in the gas storage tank remains high, this phenomenon does not occur ； (5) Internal damage to the oil distiller tank; it can only be detected through disassembly for inspection ； (6) Oil has deteriorated or been used beyond its expiration date ； (7) If the return oil check valve loses control, oil will flow back into the oil fine separator after the unit stops operating; this will result in oil leakage when the unit is started again ； (8) Damage or rupture of the air compressor oil fine separator element ； (9) There are leakage points at the minimum pressure valve, or the valve opens prematurely, resulting in low pressure inside the oil separator. This leads to a high concentration of gas in the oil mist; as a result, the flow velocity increases when the oil mist passes through the separator, the load on the separator increases, the separation efficiency declines, and fuel consumption rises.
Well, I really don’t know, but I’ve expressed my interest in finding out; I want to learn*. Thank you.
: Faulty minimum pressure valve, substandard engine oil, improper design of the oil-gas separation tank, overfilling with fuel, damaged return oil check valve, incorrect installation of the return oil pipe, high gas consumption, operation under overload and low pressure, blocked return oil pipeline
Answer: 1. The oil level is too high; too much engine oil has been added. 2. The return oil pipe is blocked. 3. The installation of the return oil pipe (distance from the bottom part of the oil separation element) does not meet the requirements. 4. The exhaust pressure is too low during unit operation. 5. The partition inside the separation tank is damaged. 6. The unit is leaking oil. 7. The oil type is incorrect, resulting in a lot of foam in the product. 8. The oil has deteriorated or been used beyond its expiration date. 9. Oil that is externally screwed on can also leak if the O-ring of the core tube does not provide a proper seal. 10. If the unit is equipped with a return oil check valve, a failure of this valve can cause oil to flow back into the oil reservoir after the unit stops operating, resulting in oil leakage when the unit is started again. 11. Damage or rupture of the oil core.
The oil not returning indicates that there is insufficient power for its circulation. The oil is mixed with the refrigerant, and its circulation also relies on the pressure difference between the high and low pressures of the refrigerant. If the pressure difference is small, the oil will remain trapped in the system and cannot return. The main reason at this time is that the air-conditioning load is too low; try to increase the load so that the air conditioner operates under a higher load. In that case, the system pressure difference will be greater, and the lubricating oil circulation will return to normal. Note: A low load resulting in insufficient force for oil circulation is a common issue. This situation may also be caused by other reasons.
The chilled water temperature is low, and the exhaust gas temperature is low
Poor return oil flow is caused by a clogged or damaged return oil check valve, or by an excessive amount of lubricating oil. It is caused by excessive lubricant foam, the lubricant having aged after being used for too long, or perforations in the oil filter element.