TECHNICAL FIELD

The present disclosure relates to an oil dehydrator, comprising; a vacuum chamber, a vacuum pump for establishing a negative pressure within the vacuum chamber and for fluid transportation of water and air out from the vacuum chamber through an outlet opening, and a pipe for fluid transportation of oil into and out from the vacuum chamber. The disclosure further relates to a system for dehydrating oil comprising an oil dehydrator and a method for dehydrating oil with an oil dehydrator.

BACKGROUND

An oil dehydrator is used for dehydrating oils, such as gear, lubricating, compressor, or hydraulic oils, that have been contaminated with water. Water contamination of oil is a common problem in many industrial applications and the need for dehydrating oils are increasing with new and more environmental friendly oil qualities that often are more hygroscopic and absorb more water.

In a typical industrial oil system the oil can be contaminated with water in different ways, such as for example through leakage of water into the oil system or from transportation of water vapour contained in humid air. All forms of water in the oil may have direct consequences to the oil system, such as for example changes in TAN (total acid number), pH and viscosity.

Water coexists with oil in either a dissolved state, an emulsified state or in a free state, where the dissolved state is the lowest level of moisture contamination of many oil types. Water in the free state is separate from the oil in the system and can many times be visually identified. The specific gravity of most oils is less than the specific gravity of water, so water usually collects at the bottom of for example reservoirs in the oil system and due to this reason free water may be removed by draining through a reservoir drain port. In the emulsified state, the water has blended with the oil. Water in the emulsified state will mostly remain in the blended state and not separate from the oil like free water. In the dissolved state, water has been dissolved into the oil. When the temperature of the oil increases, the capacity to absorb water increases, and when the oil cools down with a high level of dissolved water, the free water comes out of the oil. The dissolved water is derived from ambient air humidity slowly interacting with the oil over time. Usually, the older the oil gets, the more hygroscopic the oil will become.

The water saturation point of an oil is the point above which water is in free form. For many oils, the water saturation point is 200-600 ppm, and for environmentally friendly oils 1000-5000 ppm, depending on the age and condition of the oil. If an oil system for example requires a water saturation point of 100 ppm as an upper limit, the free and emulsified water as well as a significant portion of the dissolved water must be removed from the oil in order to meet the system requirements.

To manage the water contaminated oil, a traditional oil dehydrator of the vacuum type can be used for dehydrating the oil so that free water, emulsified water and a high portion of the dissolved water is removed from the oil. A traditional oil dehydrator of the vacuum type can be used for dehydrating oils in oil systems or oil reservoirs. Typically, this type of traditional oil dehydrators are first heating the oil if necessary and are thereafter applying a negative pressure to the oil so that the water contaminating the oil is evaporating and the water vapour formed can be transported away from the oil system.

Traditional oil dehydrators of the vacuum type are for example disclosed in the patent documents U.S. Pat. Nos. 4,681,660 A, 5,211,856 A, WO 99/65588 A1 and CN 200948367 Y. Other types of oil dehydrators are also known, such as positive pressure dehydrators. A dehydrator of this type is disclosed in patent document WO 2010/042663 A2.

There are many disadvantages with this traditional type of oil dehydrators. For example, they are heavy and complicated in construction, which means that they need to be built on a wheeled platform or placed on a trolley so that the oil dehydrator can be transported between different oil cleaning locations. Further, the oil dehydrators of this type are very costly to produce and thus expensive to purchase for a user, especially if they should be used in hazardous locations or explosion proof areas, where the electrical components must be specifically designed and tested. If for example many oil dehydrators are needed within an industry or on a ship, high investments in these systems are needed. Another problem is that when an oil dehydrating process has been completed, a high volume of oil residues are contained in the oil dehydrator due to the design of the oil dehydrator. This means that there is a risk that one type of oil can be contaminated with oil residues of another type if oil systems with different types of oil are being cleaned.

There is thus a need for an improved oil dehydrator which is; efficient, easy and flexible to use, also in explosion proof areas; lightweight in construction; simple to produce at a cost that is much lower than the cost of traditional oil dehydrators; and possible to use in systems with different oils without contamination from residual oils contained in the oil dehydrator.

SUMMARY

An object of the present disclosure is to provide an oil dehydrator, a system for dehydrating oil comprising an oil dehydrator and a method for dehydrating oil with an oil dehydrator, where the previously mentioned problems are avoided. This object is at least partly achieved by the features of the independent claims. The dependent claims contain further developments of the oil dehydrator, the system for dehydrating oil comprising an oil dehydrator and the method for dehydrating oil with an oil dehydrator.

The disclosure concerns an oil dehydrator, comprising; a vacuum chamber, a vacuum pump arranged at an upper end region of the vacuum chamber for establishing a negative pressure within the vacuum chamber and for fluid transportation of water and air out from the vacuum chamber through an outlet opening, and a pipe for fluid transportation of oil into and/or out from the vacuum chamber. The pipe is connected to a lower end region of the vacuum chamber, wherein the vacuum chamber at the lower end region has at least one flow channel fluidly connecting the vacuum chamber and the pipe. An orifice check valve is arranged between the vacuum chamber and the pipe for controlling the flow of oil into and out from the vacuum chamber through the at least one flow channel. Advantages with these features are that the oil dehydrator is constructed in a way that makes it easy and flexible to use also in explosion proof areas, since no electrical components are present in the design. Further, the oil dehydrator is lightweight in construction with few components, which makes it simple to produce at a cost that is much lower than the cost of traditional oil dehydrators. The oil dehydrator may with this construction be designed as a portable unit that is easy to move from one oil reservoir to another, so that one person easily can lift and carry the oil dehydrator. The construction also gives the possibility to design the oil dehydrator as a stationary unit for a specific oil reservoir, such as an oil reservoir in a pump system. The orifice check valve efficiently controls the flow of oil into and out from the vacuum chamber and has a design that supports the compact and lightweight construction of the oil dehydrator. The orifice check valve secures that the oil is emptied from the vacuum chamber so that the oil dehydrator is possible to use in systems with different oils without contamination from oil residues contained in the oil dehydrator.

According to an aspect of the disclosure, the orifice check valve is configured to switch an operational state between an open mode allowing oil to flow out from the vacuum chamber, and a closed mode, wherein the orifice check valve is controlling the flow of oil through the at least one flow channel into the vacuum chamber so that the flow area in the closed mode is lower than the flow area in the open mode. The orifice check valve thus regulates the flow of oil through the at least one flow channel, with a larger flow area when emptying the vacuum chamber for an efficient flow of oil out from the vacuum chamber.

According to another aspect of the disclosure, the vacuum chamber has at least one inlet flow channel at the lower end region, and at least one outlet flow channel at the lower end region, where the at least one outlet flow channel is separately arranged from the at least one inlet flow channel. In this way the flow of oil into and out from the vacuum chamber can be controlled in an efficient way with different flow channels.

According to a further aspect of the disclosure, the vacuum pump is a vacuum ejector pump. Advantages with this pump type are that the vacuum ejector pump is simple in construction and that no electrical components are involved in the construction, which makes the oil dehydrator possible to use also in explosion proof areas.

According to another aspect of the disclosure, the vacuum pump is connected to a timer valve, which is controlling a flow of compressed air through the vacuum ejector pump. The timer valve is configured to switch an operational state between an open mode allowing compressed air to flow through the vacuum ejector pump, and a closed mode preventing compressed air to flow through the vacuum ejector pump. The timer valve controls the oil dehydration process through the steering of compressed air to the vacuum ejector pump.

According to another aspect of the disclosure, the orifice check valve comprises a valve plate with at least one orifice, where the valve plate is arranged for controlling the flow of oil out from the vacuum chamber through the at least one flow channel, allowing oil to flow into the at least one flow channel through the at least one orifice, when the orifice check valve is in its closed mode. In this way a negative pressure can be efficiently established within the vacuum chamber when drawing oil into the chamber through the at least one orifice in the valve plate.

According to a further aspect of the disclosure, an inner tube is arranged inside the vacuum chamber, where the inner tube has a lower tube end that is in fluid communication with the at least one flow channel, and an upper tube end provided with at least one spray nozzle, where the spray nozzle is arranged for spraying oil into the vacuum chamber. The inner tube and the spray nozzle provide an efficient distribution of oil in the vacuum chamber, allowing oil to flow from the upper end region of the vacuum chamber so that an efficient evaporation of the water is achieved.

According to other aspects of the disclosure, the vacuum chamber is filled with a filler material that is increasing the contact surface area between the oil and the air in the vacuum chamber, where the filler material can be a random packing material. The filler material increases the contact surface between the oil and the air to further increase the evaporation rate of the water in the oil. A random packing material is providing an efficient surface structure within the vacuum chamber.

According to another aspect of the disclosure, a first air inlet opening is arranged in the lower end region of the vacuum chamber, where the first air inlet opening allows air to flow into the vacuum chamber. Through the flow of air into the chamber, the evaporation process can be made more efficient since the oil is mixing with incoming air.

According to another aspect of the disclosure, a float valve is arranged inside the vacuum chamber at the upper end region for controlling the fluid transportation of water and air out from the vacuum chamber through the outlet opening. The float valve is configured to switch an operational state between an open mode allowing water and air to flow out from the vacuum chamber through the outlet opening, and a closed mode preventing water and air to flow out from the vacuum chamber through the outlet opening. The float valve secures that the oil cannot leak out from the upper part of the vacuum chamber, which is important to prevent oil contamination of the surrounding environment. The float valve is simple in construction, which makes it simple to produce at a low cost.

According to a further aspect of the disclosure, an oil filter is arranged inside the vacuum chamber after the at least one inlet flow channel. The oil filter is cleaning the oil so that unwanted particles or other contaminations can be removed from the oil.

According to another aspect of the disclosure, a second air inlet opening is arranged at the upper end region of the vacuum chamber, where the second air inlet opening allows compressed air to flow into the vacuum chamber via a preloaded check valve, where the preloaded check valve is configured to switch an operational state between an open mode allowing compressed air to flow into the vacuum chamber through the second air inlet opening, and a closed mode preventing compressed air to flow into the vacuum chamber through the second air inlet opening. In this way the vacuum chamber can be emptied in a fast way by the compressed air that is forcing the oil to flow out from the vacuum chamber.

The disclosure further concerns a system for dehydrating oil comprising an oil dehydrator, wherein the system comprises an oil reservoir and a compressed air source. The system can also comprise an oil separating unit.

The disclosure further concerns a method for dehydrating oil with an oil dehydrator. A negative pressure is applied to the vacuum chamber with the vacuum pump and the operational state of the orifice check valve is switched to a closed mode, in which oil is prevented from flowing out from the vacuum chamber. Oil is drawn into the vacuum chamber from an oil reservoir through the pipe and the at least one flow channel, and water and air are transported out from the vacuum chamber with the vacuum pump through the outlet opening. The applying of the negative pressure to the vacuum chamber with the vacuum pump is stopped and the operational state of the orifice check valve is switched to an open mode, wherein oil is flowing out from the vacuum chamber through the at least one flow channel. Advantages with these features are that the oil dehydrator is operated in a way for an efficient dehydration of the oil. The oil dehydrator is operated in cycles and a number of cycles may be processed after each other so that a continuous process is achieved and an efficient dehydration of the oil is accomplished.

According to another aspect of the disclosure, the orifice check valve is switching the operational state to the closed mode by the flow of oil drawn into the vacuum chamber when the negative pressure is applied to the vacuum chamber; and wherein the orifice check valve is switching the operational state to the open mode by the flow of oil out from the vacuum chamber when the negative pressure is no longer applied to the vacuum chamber. In this way the orifice check valve is self-operating without the need for separate valve control means. The flow of oil into and out from the vacuum chamber is regulating the valve.

According to another aspect of the disclosure, an inner tube is arranged inside the vacuum chamber. The inner tube has a lower tube end that is in fluid communication with the at least one flow channel, and an upper tube end provided with at least one spray nozzle, wherein the spray nozzle is spraying oil into the upper end region of the vacuum chamber when the vacuum pump is applying a negative pressure to the vacuum chamber and the orifice check valve is in the closed mode. The inner tube and the spray nozzle provide an efficient distribution of oil in the vacuum chamber, allowing oil to flow from the upper end region of the vacuum chamber so that an efficient evaporation of the water is achieved.

According to a further aspect of the disclosure, air is flowing into the vacuum chamber through a first air inlet opening arranged in the lower end region of the vacuum chamber when the vacuum pump is applying a negative pressure to the vacuum chamber and the orifice check valve is in the closed mode. Through the flow of air into the chamber, the evaporation process can be made more efficient since the oil is mixing with incoming air.

According to another aspect of the disclosure, a flow of compressed air is applied to the vacuum chamber via a preloaded check valve and a second air inlet opening arranged at the upper end region of the vacuum chamber, when the negative pressure is no longer applied to the vacuum chamber, so that oil is forced to flow out from the vacuum chamber through the at least one flow channel. In this way the vacuum chamber can be emptied in a fast way by the compressed air that is forcing the oil to flow out from the vacuum chamber.

