FIELD OF THE INVENTION

The present invention relates to a cooling pipe arrangement for a vacuum pumping system.

BACKGROUND

Vacuum pumping systems are used in various different industries to pump gas out of a desired chamber using one or more vacuum pumps. Vacuum pumps tend to generate a large amount of heat during operation. Thus, vacuum pumping systems typically include cooling lines carrying cooling fluid (e.g. water) for cooling the vacuum pumps.

It is desirable to prevent leakage from the piping used for the cooling lines.

SUMMARY OF INVENTION

According to a first aspect, there is provided a pipe arrangement for conveying cooling fluid for cooling a vacuum pumping system, comprising a first pipe section containing and arranged to convey a first cooling fluid having a first temperature, a second pipe section containing and arranged to convey a second cooling fluid having a second temperature lower than the first temperature, and a third pipe section fluidly connected to the first and second pipe sections. The third pipe section is arranged to receive the first cooling fluid from the first pipe section and to receive the second cooling fluid from the second pipe section. The third pipe section contains and is arranged to convey a mixture of the first and second cooling fluids, wherein the mixture has a third temperature lower than the first temperature and greater than the second temperature. The third pipe section is formed from a different type of material to the first pipe section.

The third pipe section may be formed from a plastic material. The third pipe section may be formed from PA12.

The first pipe section may be formed from a metallic material.

The third pipe section may be formed from stainless steel.

The third pipe section may be formed from a different type of material to the second pipe section.

The second pipe section may be formed from the same type of material as the first pipe section.

The first and second cooling fluids may be the same type of fluid.

The type of fluid may be water. The first temperature may be greater than 80°C, the second temperature may be less than 80°C, and the third temperature may be less than or equal to 80° C.

The second temperature may be less than 50°C and the third temperature may be between 50°C and 80°C. The first, second and third pipe sections may be connected together to form a T-joint or cross joint.

According to a second aspect, there is provided a vacuum pumping system comprising a vacuum pump and a cooling system arranged to cool the vacuum pump, the cooling system comprising cooling lines comprising the pipe arrangement according to the first aspect.

The cooling lines may comprise a first cooling line comprising the first pipe section, wherein the first cooling line passes proximate to or through the vacuum pump to cool the vacuum pump, and a second cooling line comprising the second pipe section, wherein the second cooling line does not pass proximate to or through the vacuum pump, wherein the first cooling line connects to the second cooling line at a point on the first cooling line downstream of the vacuum pump.

The first cooling fluid may be cooling fluid which has been used to cool the vacuum pump by absorbing heat therefrom. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a schematic illustration (not to scale) showing a vacuum pumping system comprising a cooling pipe arrangement; and

Figure 2 is a schematic illustration (not to scale) showing a close up view of a pipe arrangement of the vacuum pumping system of Figure 1.

DETAILED DESCRIPTION

Figure 1 is a schematic illustration (not to scale) showing a vacuum pumping system 100. The vacuum pumping system 100 comprises a vacuum pump 110 and a plurality of cooling lines 120a-d.

The vacuum pump 110 is arranged to pump gas out of a particular location (e.g. a chamber in a manufacturing facility) via one or more vacuum pumping lines (not shown). The vacuum pump 110 may be any type of vacuum pump, e.g. a rotary vane pump, diaphragm pump, liquid ring pump, scroll pump or screw pump. The operation of vacuum pumps and their industrial application are well understood and will not be described herein for the sake of brevity.

During operation, the vacuum pump 110 generates a significant amount of heat. In order to cool the vacuum pump 110, the cooling lines 120a-d are arranged to convey cooling fluid (e.g. a liquid such as water) proximate to (or through) the vacuum pump 110 to absorb the generated heat into the cooling fluid and to carry the absorbed heat away from the vacuum pump 110.

In more detail, the cooling lines 120a-d comprise a first cooling line 120a, a second cooling line 120b, a third cooling line 120c and a fourth cooling line 120d. The cooling lines 120a-d are formed from a plurality of pipe sections joined together. The direction of travel of the cooling fluid conveyed by the cooling lines 120a-d is shown by arrows 130 in Figure 1.

The first cooling line 120a is arranged to receive cooling fluid from a cooling fluid source (such as a cooling water tank or a cooling fluid source external to the vacuum pumping system 100), convey the received cooling fluid therethrough, and output the conveyed cooling fluid into the second and third cooling lines 120b, 120c. The second cooling line 120b is arranged to receive cooling fluid from the first cooling line 120a, convey the received cooling fluid therethrough, and output the conveyed cooling fluid into the fourth cooling line 120d.

The second cooling line 120b passes proximate to (or through) the vacuum pump 110 such that the cooling fluid conveyed by the second cooling line 120b absorbs and carries away heat generated by the vacuum pump 110. Thus, the cooling liquid in the second cooling line 120b downstream of the vacuum pump 110 is at a higher temperature than the cooling fluid in the second cooling line 120b upstream of the vacuum pump 110. The third cooling line 120c is arranged to receive cooling fluid from the first cooling line 120a, convey the received cooling fluid therethrough, and output the conveyed cooling fluid into the fourth cooling line 120d. The third cooling line 120c does not pass proximate to or through the vacuum pump 110. Alternatively, the third cooling line 120c may pass proximate to or through a cooler part of the vacuum pump 110 (e.g. a motor of the vacuum pump 110) than the part of the vacuum pump 110 that the second cooling line 120b passes proximate to or through. Thus, the cooling fluid conveyed by the third cooling line 120c does not absorb heat from the vacuum pump 110 and is at substantially the same temperature throughout the third cooling line 120c. The temperature of the cooling fluid in the third cooling line 120c is substantially the same as the temperature of the cooling fluid in the second cooling line 120b upstream of the vacuum pump 110.

The fourth cooling line 120d is arranged to receive cooling fluid from the second and third cooling lines 120b, 120c, convey the received cooling fluid therethrough, and output the conveyed cooling fluid to another location, e.g. a location external to the vacuum pumping system 100 for recirculation. Specifically, the fourth cooling line 120d is arranged to receive from the second cooling line 120b cooling fluid which has absorbed the heat generated by the vacuum pump 110, i.e. cooling fluid from the second cooling line 120b downstream of the vacuum pump 110. Thus, the cooling fluid entering the fourth cooling line 120d from the second cooling line 120b is at higher temperature than the cooling fluid entering the fourth cooling line 120d from the third cooling line 120c. The cooling fluid entering the fourth cooling line 120d from the second and third cooling lines 120b, 120c mix in the fourth cooling line 120d, such that the mixture is at a lower temperature than the cooling fluid entering from the second cooling line 120b and at a higher temperature than the cooling fluid entering from the third cooling line 120c. In other words, in effect, the cooler cooling fluid entering from the third cooling 120c acts to cool the hotter cooling fluid entering from the second cooling line 120b by mixing therewith.

Different pipe sections used to form the cooling lines 120a-d can be formed from different types of material depending on the temperature of the cooling fluid that they convey. In particular, according to an embodiment of the invention, a pipe arrangement 200 at the connection point between the second, third and fourth cooling lines 120b-d can make use of different types of material for different sections of pipe, as will now be described in more detail with reference to Figure 2.

Figure 2 is a schematic illustration (not to scale) showing a close up view of the pipe arrangement 200.

The pipe arrangement 200 comprises a first pipe section 210, a second pipe section 220, and a third pipe section 230. The first pipe section 210 forms part of the second cooling line 120b described above, the second pipe section 220 forms part of the third cooling line 120c described above, and the third pipe section 230 forms part of the fourth cooling line 120d described above. Specifically, the pipe arrangement 200 comprises an intersection of the second, third and fourth cooling lines 120b-d.

The first, second and third pipe sections 210, 220, 230 are fluidly connected together such that an input of the third pipe section 230 is arranged to receive cooling fluid from outputs of the first and section pipe sections 210, 220. Specifically, in this embodiment, the first, second and third pipe sections 210, 220, 230 are connected together to form a T-joint. Alternatively, the first, second and third pipe section may be connected together to form a cross joint. The first, second and third pipe sections may be connected together using any appropriate connection means, e.g. by use of a screw threaded connector or other appropriate commercially available connectors such as a plastic quick connector. The first pipe section 210 is arranged to convey a first fluid having a first temperature towards the third pipe section 230, and to output the first fluid into the third pipe section 230. The second pipe section 220 is arranged to convey a second fluid having a second temperature towards the third pipe section 230, and to output the second fluid into the third pipe section 230. The third pipe section 230 is arranged to receive the first fluid from the first pipe section 210, receive the second fluid from the second pipe section 220, and to convey a mixture of the first and second fluids away from the first and second pipe sections 210, 220. The direction of travel of the cooling fluid conveyed by the first, second and third pipe sections is shown by arrows 240 in Figure 2.

The mixture conveyed by the third pipe section 230 has a third temperature lower than the first temperature and greater than the second temperature. The third pipe section 230 is formed from a different type of material to the first pipe section 210. In this embodiment, the third pipe section 230 is formed from a plastic material. Specifically, in this embodiment, the third pipe section 230 is formed from Polyamide 12 “PA12” (also known as Nylon 12). In this embodiment, the first pipe section 210 is formed from a metallic material. Specifically, the first pipe section 210 is formed from stainless steel. Using different types of material for the first and third pipe sections allows a relatively cheap but relatively less temperature resistant material (e.g. PA12) to be used for a pipe section which does not carry high temperature cooling fluid, whilst a relatively expensive but relatively more temperature resistant material (e.g. stainless steel) is used for a pipe section which does carry high temperature cooling fluid. In this embodiment, the third pipe section 230 is formed from a different type of material to the second pipe section 220. Also, in this embodiment, the second pipe section 220 is formed from the same material as the first pipe section 210. Specifically, in this embodiment, the second pipe section 220 is formed from stainless steel. However, it will be appreciated that the second pipe section 220 may alternatively be formed from the same material as the third pipe section 230 and/or a different type of material to the first pipe section 210.

In this embodiment, the first, second and third pipe sections 210, 220, 230 are arranged to convey the same type of fluid. In other words, the first fluid is the same type of fluid as the second fluid and the same type of fluid as the mixture. Specifically, in this embodiment, the type of fluid is water.

In this embodiment, the first temperature is greater than 80°C, the second temperature is less than 80°C, and the third temperature is less than or equal to 80°C. For example, the second temperature may be less than 50°C and the third temperature may be between 50°C and 80°C. It has been found that piping of the kind described herein which is formed from PA12 tends to leak when exposed to temperatures of greater than 80°C. Piping formed from stainless steel, on the other hand, tends to be able to withstand temperatures greater than 80°C without leaking. Thus, PA12 can be used for the third pipe section 230 (which conveys fluid having a temperature of 80°C or less) without a significant risk of leaks occurring due to temperature, whilst stainless steel is used for the first pipe section 210 as the first pipe section 210 conveys fluid having a temperature of over 80°C. Thus, a pipe arrangement for a cooling system for a vacuum pumping system is provided.

Advantageously, by mixing relatively cool fluid with relatively hot fluid in the third pipe section and using a different type of material for the third pipe section compared to the first pipe section, the above-described pipe arrangement tends to allow the use of a cheaper more lightweight material for some of the piping in the vacuum pumping system without overly compromising the structural integrity of the piping with regard to leaks. In embodiments in which the second pipe section is formed from a different type of material to the third pipe section, further cost reductions tend to be achieved, Advantageously, the above pipe arrangement tends to mean that no further complicated additional equipment is required to cool the cooling fluid in the second cooling line.

In some alternative embodiments, the fluid in the second pipe section comes from a different location to that shown in Figure 1. For example, the fluid in the second pipe section may come from a cooling line which passes proximate to or through a cooler part of the vacuum pump (e.g. a motor of the vacuum pump) to the part of the vacuum pump that the second cooling line passes proximate to or through (e.g. a low vacuum side of the vacuum pump). These embodiments advantageously tend to allow a detour line to run from a cool part of the vacuum pump which is relatively close to the hotter part of the vacuum pump, which tends to enable a simpler structure to be used. In the above embodiments, the third pipe section is formed from PA12.

However, in other embodiments, the third pipe section is formed from another type of material. For example, the third pipe section may be formed from another type of plastic suitable for conveying the mixture of the first and second fluid. Alternatively, the third pipe section may be formed a non-plastic material suitable for conveying the mixture of the first and second fluid.

In the above embodiments, the first pipe section is formed from stainless steel. However, in other embodiments, the first pipe section is formed from another type of material. For example, the first pipe section may be formed from another type of metal suitable for conveying the first fluid. Alternatively, the first pipe section may be formed from a non-metallic material suitable for conveying the first fluid.

In the above embodiments, the first, second and third pipe sections form a T-joint. However, in other embodiments, the first, second and third pipe sections form a differently shaped joint, e.g. a joint where the pipe sections are evenly angularly spaced from each other.

In the above embodiments, the first temperature is greater than 80°C, the second temperature is less than 80°C, and the third temperature is less than or equal to 80°C. However, in other embodiments in which different types of material are used for one or more of the first, second and third pipe sections, the first, second and third temperatures have different specific values or value ranges.

In the above embodiments, the first, second and third pipe sections all convey the same type of fluid. However, in other embodiments, the first and second pipe sections convey different types of fluid, and the third pipe section conveys a mixture of the different types of fluid. Reference numeral list

100 - vacuum pumping system 110 - vacuum pump 120a - first cooling line 120b - second cooling line

120c -third cooling line 120d - fourth cooling line 130 - direction of travel of cooling fluid 200 - pipe arrangement 210 - first pipe section

220 - second pipe section 230 - third pipe section 240 - direction of travel of cooling fluid